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Yuzo Miyazaki
Institute of Low Temperature Science　Water and Material Cycles
Assistant Professor
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Last Updated :2024/05/09

Researcher Profile and Settings

Affiliation

  • Institute of Low Temperature Science　Water and Material Cycles

Job Title

  • Assistant Professor

Degree

  • Ph,D, (Sci.)（The University of Tokyo）
  • Ms. (Sci.)（The University of Tokyo）

Research funding number

  • 60376655

J-Global ID

Research Interests

  • Biogeochemistry   Marine atmospheric chemistry   Atmospheric chemistry   Interaction between atmosphere and biosphere   Organic aerosol   

Research Areas

  • Natural sciences / Atmospheric and hydrospheric science
  • Environmental science/Agricultural science / Environmental dynamics

Educational Organization

Academic & Professional Experience

  • 2003 - 2007 The University of Tokyo Research Center for Advanced Science and Technology
  • 2007 Institute of Low Temperature Science
  • 2003 The University of Tokyo Research Center for Advanced Science and Technology
  • 2003 Postdoctoral Fellowships of Japan Society for the Promotion of Science

Education

  •        -   The University of Tokyo

Association Memberships

  • American Geophysical Union   日本エアロゾル学会   日本気象学会   日本地球惑星科学連合   日本大気化学会   

Research Activities

Published Papers

  • Yuhao Cui, Eri Tachibana, Kimitaka Kawamura, Yuzo Miyazaki
    Biogeosciences 20 (24) 4969 - 4980 2023/12 [Refereed][Not invited]
     
    Abstract. Fatty alcohols (FAs) are major components of surface lipids in plant leaves and serve as surface-active organic aerosols (OAs), which can act as primary biological aerosol particles (PBAPs). To elucidate the origin and formation of secondary fatty alcohols (SFAs) in atmospheric aerosols, their mass size distribution in aerosol samples obtained from a deciduous forest canopy was measured in spring, summer and autumn. The SFAs showed the highest concentration in spring (growing season), with n-nonacosan-10-ol being the most abundant. In spring and summer, the size peak of n-nonacosan-10-ol was in the particle size range >10.0 µm, whereas it was in the 1.9–3.0 µm range in autumn. The size distribution of n-nonacosan-10-ol did not show any significant correlation with that of the known biogenic tracers of pollen, soil and fungal spores in spring and summer. The overall results, together with SFAs measured in plant leaves, as well as the literature, suggest that SFAs originate mostly from plant waxes and that leaf senescence status is likely an important factor controlling the size distribution of SFAs. This study provides new insights into the possible sources of PBAPs and their effects on the ice nucleation activity of aerosols based on seasonal changes in particle size.
  • Alkuin M. Koenig, Olivier Magand, Clemence Rose, Andrea Di Muro, Yuzo Miyazaki, Aurelie Colomb, Matti Rissanen, Christopher F. Lee, Theodore K. Koenig, Rainer Volkamer, Jerome Brioude, Bert Verreyken, Tjarda Roberts, Brock A. Edwards, Karine Sellegri, Santiago Arellano, Philippe Kowalski, Alessandro Aiuppa, Jeroen E. Sonke, Aurélien Dommergue
    Environmental Science: Atmospheres 3 (10) 1418 - 1438 2023/08 [Refereed]
     
    We observed complete GEM depletion in a volcanic plume.
  • Masao Gen, Akihide Hibara, Phuong Nguyet Phung, Yuzo Miyazaki, Michihiro Mochida
    The Journal of Physical Chemistry A 127 (29) 6100 - 6108 1089-5639 2023/07/18 [Refereed]
  • Akinori Ito, Yuzo Miyazaki, Fumikazu Taketani, Yoko Iwamoto, Yugo Kanaya
    Environmental Science: Atmospheres 3 782 - 798 2023/04 [Refereed]
     
    Marine aerosol feedback on biogeochemical cycles and the climate remains highly uncertain due to the complex interplay. This review highlights recent advances in our understanding of organic aerosols, nitrogen, and iron as well as cloud properties over the Pacific Ocean.
  • Jinyoung Jung, Yuzo Miyazaki, Jin Hur, Yun Kyung Lee, Mi Hae Jeon, Youngju Lee, Kyoung-Ho Cho, Hyun Young Chung, Kitae Kim, Jung-Ok Choi, Catherine Lalande, Joo-Hong Kim, Taejin Choi, Young Jun Yoon, Eun Jin Yang, Sung-Ho Kang
    Atmospheric Chemistry and Physics 23 (8) 4663 - 4684 2023/04 [Refereed]
     
    Abstract. Accelerated warming and a decline in sea ice coverage inthe summertime Arctic Ocean can significantly affect the emissions of marineorganic aerosols and biogenic volatile organic compounds. However, how thesechanges affect the characteristics of atmospheric water-soluble organiccarbon (WSOC), which plays an important role in the climate system, remainsunclear. Thus, to improve our understanding of WSOC characteristics in therapidly changing Arctic Ocean, including its summertime fluorescencecharacteristics, we simultaneously measured atmospheric concentrations ofionic species and WSOC, a fluorescence excitation–emission matrix coupledwith parallel factor (EEM-PARAFAC) analysis of WSOC, and marine biologicalparameters in surface seawaters of the western Arctic Ocean during thesummer of 2016. WSOC was predominantly present as fine-mode aerosols(diameter <2.5 µm, median =92 %), with the meanconcentration being higher in the coastal water areas(462±130 ngC m−3) than in the sea-ice-covered areas (242±88.4 ngC m−3).Moreover, the WSOC in the fine-mode aerosols was positively correlated withthe methanesulfonic acid in the fine-mode aerosol samples collected over thesea-ice-covered areas (r=0.88, p<0.01, n=10), suggestinghigh rates of sea–air gas exchange and emissions of aerosol precursor gasesdue to sea ice retreat and increasingly available solar radiation during theArctic summer. Two fluorescent components, humic-like C1 and protein-likeC2, were identified by the PARAFAC modeling of fine-mode atmospheric WSOC.The two components varied regionally between coastal and sea-ice-coveredareas, with low and high fluorescence intensities observed over the coastalareas and the sea-ice-covered areas, respectively. Further, the humificationindex of WSOC was correlated with the fluorescence intensity ratio of thehumic-like C1 / protein-like C2 (r=0.89, p<0.01) and the WSOCconcentration in the fine-mode aerosols (r=0.66, p<0.05), withthe highest values observed in the coastal areas. Additionally, the WSOCconcentration in the fine-mode aerosols was positively correlated with thefluorescence intensity ratio of the humic-like C1 / protein-like C2 (r =0.77, p<0.01) but was negatively correlated with the biologicalindex (r=-0.69, p<0.01). Overall, these results suggestedthat the WSOC in the fine-mode aerosols in the coastal areas showed a higherdegree of polycondensation and higher aromaticity compared to that in thesea-ice-covered areas, where WSOC in the fine-mode aerosols was associatedwith relatively new, less oxygenated, and biologically derived secondaryorganic components. These findings can improve our understanding of thechemical and biological linkages of WSOC at the ocean–sea-ice–atmosphereinterface.
  • Sonia Afsana, Ruichen Zhou, Yuzo Miyazaki, Eri Tachibana, Dhananjay Kumar Deshmukh, Kimitaka Kawamura, Michihiro Mochida
    Atmospheric Environment 303 119710 - 119710 1352-2310 2023/03 [Refereed]
  • Tsukasa Dobashi, Yuzo Miyazaki, Eri Tachibana, Kazutaka Takahashi, Sachiko Horii, Fuminori Hashihama, Saori Yasui-Tamura, Yoko Iwamoto, Shu-Kuan Wong, Koji Hamasaki
    Biogeosciences 20 (2) 439 - 449 1726-4170 2023/01 
    Abstract. Water-soluble organic nitrogen (WSON) in marineatmospheric aerosols affect the water solubility, acidity, andlight-absorbing properties of aerosol particles, which are importantparameters in assessing both the climate impact and the biogeochemicalcycling of bioelements. Size-segregated aerosol and surface seawater (SSW)samples were simultaneously collected over the subtropical North Pacific toinvestigate the origin of WSON in the marine atmosphere. The fine-mode WSONconcentration (7.5 ± 6.6 ngN m−3) at 200–240∘ Ealong 23∘ N, defined as the eastern North Pacific (ENP), wassignificantly higher than that (2.4 ± 1.9 ngN m−3) at135–200∘ E, defined as the western North Pacific (WNP).Analysis of the stable carbon isotope ratio of water-soluble organic carbon(WSOC; δ13CWSOC) together with backward trajectoryindicated that most of the observed WSON in the fine particles in the ENPoriginated from the ocean surface. We found positive relations amongnitrogen-fixation rate, dissolved organic nitrogen (DON) in SSW, and theWSON concentrations. The result suggests that reactive nitrogen (DON andammonium), produced and exuded by nitrogen-fixing microorganisms in SSW,contributed to the formation of WSON aerosols. This study provides newinsights into the role of ocean-derived reactive nitrogen aerosolsassociated with marine microbial activity.
  • Kaori Kawana, Yuzo Miyazaki, Yuko Omori, Hiroshi Tanimoto, Sara Kagami, Koji Suzuki, Youhei Yamashita, Jun Nishioka, Yange Deng, Hikari Yai, Michihiro Mochida
    Journal of Geophysical Research: Atmospheres 127 (19) 2169-897X 2022/10/16 [Refereed]
  • Sonia Afsana, Ruichen Zhou, Yuzo Miyazaki, Eri Tachibana, Dhananjay Kumar Deshmukh, Kimitaka Kawamura, Michihiro Mochida
    Scientific Reports 12 (1) 2022/08/23 
    Abstract Atmospheric organic aerosol (OA) are considered as a significant contributor to the light absorption of OA, but its relationship with abundance, composition and sources are not understood well. In this study, the abundance, chemical structural characteristics, and light absorption property of HULIS and other low-to-high polar organics in PM0.95 collected in Tomakomai Experimental Forest (TOEF) were investigated with consideration of their possible sources. HULIS were the most abundant (51%), and correlation analysis revealed that biogenic secondary organic aerosols significantly contribute to HULIS. The mass spectra obtained using a high-resolution aerosol mass spectrometer (HR-AMS) showed that HULIS and highly polar water-soluble organic matter (HP-WSOM) were substantially oxygenated organic aerosol fractions, whereas water-insoluble organic matter (WISOM) had a low O/C ratio and more hydrocarbon-like structures. The WISOM fraction was the predominant light-absorbing organics. HULIS and WISOM showed a noticeable seasonal change in mass absorption efficiency (MAE365), which was highest in winter. Further, HULIS were shown to be less absorbing than those reported for urban sites. The findings in this study provide insights into the contribution of biogenic secondary OA on aerosol property and radiative forcing under varying contributions from other types of OA.
  • Yange Deng, Hiroaki Fujinari, Hikari Yai, Kojiro Shimada, Yuzo Miyazaki, Eri Tachibana, Dhananjay Deshmukh, Kimitaka Kawamura, Tomoki Nakayama, Shiori Tatsuta, Mingfu Cai, Hanbing Xu, Fei Li, Haobo Tan, Sho Ohata, Yutaka Kondo, Akinori Takami, Shiro Hatakeyama, Michihiro Mochida
    Atmospheric Chemistry and Physics 2022/05/02 
    Abstract. Filter-based offline analysis of atmospheric aerosol hygroscopicity coupled to composition analysis provides information complementary to that obtained from online analysis. However, its application itself and comparison to online analysis have remained limited to date. In this study, daily submicrometer aerosol particles (PM0.95, 50 % cutoff diameter: 0.95 μm) were collected onto quartz fiber filters in Okinawa Island, a receptor of East Asian outflow, in the autumn of 2015. The chemical composition of water-soluble matter (WSM) in PM0.95 and PM0.95 itself, and their respective hygroscopicities were characterized through the offline use of an aerosol mass spectrometer and a hygroscopicity tandem differential mobility analyzer. Thereafter, results were compared with those obtained from online analyses. Sulfate dominated the WSM mass (60 %), followed by water-soluble organic matter (WSOM, 20 %) and ammonium (13 %). WSOM accounted for most (93 %) of the mass of extracted organic matter (EOM) and the atomic O to C ratios (O : C) of WSOM and EOM were high (mean ± standard deviation were, respectively, 0.84 ± 0.08 and 0.79 ± 0.08), both of which indicate highly aged characteristics of the observed aerosol. The hygroscopic growth curves showed clear hysteresis for most samples. At 85 % RH, the calculated hygroscopicity parameter κ of the WSM (κWSM), WSOM, EOM, and PM0.95 (κPM0.95) were, respectively, 0.50 ± 0.03, 0.22 ± 0.12, 0.20 ± 0.11, and 0.47 ± 0.03. An analysis using the thermodynamic E-AIM model shows, on average, that inorganic salts and WSOM respectively contributed 88 % and 12 % of the κWSM (or κPM0.95). High similarities were found between offline and online analysis for chemical compositions that are related to particle hygroscopicity (the mass fractions and O : C of organics, and the degree of neutralization), and also for aerosol hygroscopicity. As possible factors governing the variation of κWSM, the influences of WSOM abundance and the neutralization of inorganic salts were assessed. At high RH (70–90 %), the hygroscopicity of WSM and PM0.95 was affected considerably by the presence of organic components; at low RH (20–50 %), the degree of neutralization could be important. This study not only characterized aerosol hygroscopicity at the receptor site of East Asian outflow, but also shows that the offline hygroscopicity analysis is an appropriate method, at least for aerosols of the studied type. The results encourage further applications to other environments and to more in-depth hygroscopicity analysis, in particular for organic fractions.
  • Sonia Afsana, Ruichen Zhou, Yuzo Miyazaki, Eri Tachibana, Dhananjay Kumar Deshmukh, Kimitaka Kawamura, Michihiro Mochida
    2022/03/28
  • Origin of water-soluble organic aerosols at the Maïdo high-altitude observatory, Réunion Island in the tropical Indian Ocean
    Simu, S. A, Y. Miyazaki, E. Tachibana, H. Finkenzeller, J. Brioude, A. Colomb, O. Magand, B. Verreyken, S. Evan, R. Volkamer, T. Stavrakou
    Atmos. Chem. Phys. 21 17017 - 17029 2021/11 [Refereed][Not invited]
  • Md Mozammel Haque, Santosh Kumar Verma, Dhananjay K. Deshmukh, Bhagawati Kunwar, Yuzo Miyazaki, Kimitaka Kawamura
    Chemosphere 279 0045-6535 2021/09 
    Total suspended particulate (TSP) samples were collected in a deciduous broadleaf forest in Sapporo, Hokkaido, Japan, from January to December 2010 to understand the molecular composition and abundance of sugar compounds (SCs) in atmospheric aerosols. We analyzed the samples for anhydrosugars, primary sugars, and sugar alcohols using a gas chromatograph-mass spectrometer. The annual mean concentrations of total SCs ranged from 16.1 to 1748 ng m−3 (avg. 311 ng m−3) with maxima in spring (avg. 484 ng m−3) and minima in winter (avg. 28.2 ng m−3). Primary sugars and sugar alcohols followed the seasonal pattern of total SCs. High levels of anhydrosugars in winter (avg. 22.9 ng m−3) suggest a contribution of biomass burning from domestic heating due to lower ambient temperature. The high levels of arabitol and mannitol in spring followed by summer and autumn denote the contribution from multiple sources, i.e., growing vegetation and fungal spores in Sapporo forest. We observed an enhanced contribution of bioaerosols emitted from plant blossoms in spring and leaf decomposition in autumn. The identical seasonal trends of glucose and trehalose implied their similar sources in forest aerosols. Conversely, the highest concentration of sucrose in spring was due to the pollen emissions by blooming plants. Positive matrix factorization (PMF) analyses of the SCs suggested that organic aerosols in the deciduous forest are associated with the emissions from multiple sources, including vegetation, microbes, pollens, and wintertime biomass burning. The PMF analysis also suggested that vegetation is the primary carbon source in the forest atmosphere. The diagnostic mass ratios of levoglucosan to mannosan demonstrated the dominance of softwood burning. We noted that the meteorological parameters substantially affect the emission sources and seasonal concentrations of SCs in the deciduous forest.
  • Miyazaki, Y., Suzuki, K., Tachibana, E., Yamashita, Y., M{\"u}ller, A., Kawana, K., Nishioka, J.
    Scientific Reports 11 (1) 2045-2322 2021
  • Yuzo Miyazaki, Koji Suzuki, Eri Tachibana, Youhei Yamashita, Astrid Mueller, Kaori Kawana, Jun Nishioka
    SCIENTIFIC REPORTS 10 (1) 2045-2322 2020/10 
    Linking the amount of organic matter (OM) in sea spray aerosols (SSAs) to biological processes in ocean surface is essential for understanding marine aerosol formation and their potential to affect cloud formation. To date, chlorophyll (Chl) a concentration has been widely used as a surrogate for surface phytoplankton biomass or productivity to predict the relative abundance of OM in SSAs (OMSSA). Here we show a new index to present-OMSSA using concentrations of Chl a and chlorophyllide (Chllide) a, which is a breakdown product of Chl a and has been used as a biomarker of senescent algal cells. The index was compared with submicrometer OMSSA, based on surface seawater and aerosol samples obtained during the pre-bloom in the western subarctic Pacific. Our results showed that the OMSSA was highly correlated with this unique index, suggesting that the OMSSA was closely linked with senescent algal cells and/or cell lysis. Furthermore, the hygroscopicity parameters. derived from water-extracted SSA samples implied a reduction in the SSA hygroscopicity with increasing senescent status of phytoplankton. The index can represent OMSSA on a timescale of a day during the pre-bloom period, which should be further examined over different oceanic regions.
  • Astrid Muller, Kazuma Aoki, Eri Tachibana, Tsutom Hiura, Yuzo Miyazaki
    ATMOSPHERIC ENVIRONMENT 229 1352-2310 2020/05 [Refereed][Not invited]
     
    Terrestrial biogenic emissions of organic matter can affect the optical properties of atmospheric aerosols and thus impact the radiation budget. To investigate this, the chemical parameters of submicrometer water-soluble aerosols (WSA) collected on filters were compared to optical properties measured by a sky radiometer at a cool-temperate forest site in northern Japan. From June to December 2015, the WSA samples were collected within the forest canopy, while aerosol optical depth (AOD), single scattering albedo (SSA), absorption Angstrom exponent (AAE), and scattering Angstrom exponent (SAE) were retrieved above the canopy. The optical properties were compared with the filter-based chemical parameters only when the vertical transport of aerosol particles from the forest canopy to the air above it was significant. The result showed that the AOD and the mass concentrations of WSA exhibited similar and distinct seasonal variations with peaks in summer and autumn. In summer, sulfate accounted for 60% of the mass of WSA, which was linked to a high SSA (>0.95), low AAE (1.15 +/- 0.84), and low SAE (1.25 +/- 0.22). In contrast, water-soluble organic matter (WSOM) accounted for 70% of the mass of WSA in autumn. This large fraction of WSOM was associated with a decrease in SSA (0.90-0.95) and an increase in AAE (2.45 +/- 0.91) and SAE (1.46 +/- 0.15). The results suggest that in summer, aerosol particles with a greater size range corresponded to aerosol chemical compositions dominated by sulfate. In contrast, smaller particles with a strong light absorption at shorter wavelengths, were likely important in autumn and associated with a composition dominated by WSOM. The majority of WSOM in autumn has previously been associated with emissions of a-pinene from the forest floor and the subsequent formation of biogenic secondary organic aerosols (BSOA). This study indicates that a-pinene-derived SOAs, mostly originating from the forest floor, were associated with a summer to autumn decrease in SSA. This process can modulate the radiative effect on a regional scale.
  • Yu Xu, Yuzo Miyazaki, Eri Tachibana, Kei Sato, Sathiyamurthi Ramasamy, Tomoki Mochizuki, Yasuhiro Sadanaga, Yoshihiro Nakashima, Yosuke Sakamoto, Kazuhide Matsuda, Yoshizumi Kajii
    Environmental Science and Technology 54 (3) 1406 - 1414 0013-936X 2020/02/04 [Refereed][Not invited]
     
    Copyright © 2020 American Chemical Society. Water-soluble organic nitrogen (WSON) affects the formation, chemical transformations, hygroscopicity, and acidity of organic aerosols as well as biogeochemical cycles of nitrogen. However, large uncertainties exist in the origins and formation processes of WSON. Submicrometer aerosol particles were collected at a suburban forest site in Tokyo in summer 2015 to investigate the relative impacts of anthropogenic and biogenic sources on WSON formations and their linkages with aerosol liquid water (ALW). The concentrations of WSON (ave. 225 ± 100 ngN m-3) and ALW exhibited peaks during nighttime, which showed a significant positive correlation, suggesting that ALW significantly contributed to WSON formation. Further, the thermodynamic predictions by ISORROPIA-II suggest that ALW was primarily driven by anthropogenic sulfate. Our analysis, including positive matrix factorization, suggests that aqueous-phase reactions of ammonium and reactive nitrogen with biogenic volatile organic compounds (VOCs) play a key role in WSON formation in submicrometer particles, which is particularly significant in nighttime, at the suburban forest site. The formation of WSON associated with biogenic VOCs and ALW was partly supported by the molecular characterization of WSON. The overall result suggests that ALW is an important driver for the formation of aerosol WSON through a combination of anthropogenic and biogenic sources.
  • Tomoki Mochizuki, Satoru Takanashi, Ryuichi Wada, Yuzo Miyazaki, Takashi Nakano, Akira Tani
    JOURNAL OF AGRICULTURAL METEOROLOGY 76 (1) 36 - 43 0021-8588 2020 [Refereed][Not invited]
     
    Monoterpenes and isoprene emitted from forest ecosystems contribute to the formation of secondary organic aerosols (SOAs) and photochemical oxidants (O-x) and affect an ecosystem's carbon budget. Initial oxidation products of isoprene, methacrolein (MACR) and methyl vinyl ketone (MVK), are key intermediate compounds for the formation of SOAs and O-x, but the production and loss processes of MACR and MVK and its controlling factors within a forest have not been revealed. To address them within a forest and the behavior of related compounds, we measured vertical concentrations and fluxes of monoterpenes, isoprene, and MACR+MVK in a pine-oak forest during summer. Monoterpene concentrations were the highest near the forest floor. A higher isoprene concentration was observed at the height of the Quercus trees. High positive fluxes of monoterpenes and isoprene were observed during the day. The average flux of isoprene during the measurement period was 2.6 times higher than that of monoterpene. Quercus in the lower layer of the forest can be an important source of isoprene, even though the light intensity was estimated much lower than that of red pine canopy. The MACR+MVK concentrations did not show clear vertical gradient patterns. Both positive and negative MACR+MVK fluxes were observed and large positive MACR+MVK fluxes were occasionally observed under a relatively high O-3 concentration and isoprene flux around noon or during the afternoon, suggesting that they are produced more frequently by reaction with reactive species including O-3 at a higher temperature. Our results demonstrate that, to investigate sink and source dynamics of MACR+MVK above a forest, it is necessary to separately estimate production rate of MACR+MVK, which depends on isoprene emission from the target and surrounding forests, O-3 concentration, temperature, and its deposition rate, which is controlled by its concentration and micrometeorological factors.
  • Ryuichi Wada, Masahito Ueyama, Akira Tani, Tomoki Mochizuki, Yuzo Miyazaki, Kimitaka Kawamura, Yoshiyuki Takahashi, Nobuko Saigusa, Satoru Takanashi, Takafumi Miyama, Takashi Nakano, Seiichiro Yonemura, Yutaka Matsumi, Genki Katata
    Journal of Agricultural Meteorology 76 (1) 1 - 10 0021-8588 2020 [Refereed][Not invited]
     
    © 2020, Society of Agricultural Meteorology of Japan. All rights reserved. Trace atmospheric gases in the biosphere, such as ozone (O3), nitrogen oxides (NOx), and biogenic volatile organic compounds (BVOCs), can affect the carbon cycle as well as the climate. Vertical profiles of nitric oxide (NO), O3, and volatile organic compound (VOC) concentrations were measured at a Japanese larch (Larix kaempferi) forest in the foothills of Mt. Fuji in Japan over an 11-day period in July 2012. The concentrations of NO and O3 during the day were highest above the canopy and decreased with proximity to the forest floor, but those of the VOCs had minimum and maximum points at different levels within the canopy depending on the species. Inverse multilayer models were applied to identify vertical sink and source distribution of these gases within the canopy. The model estimated that there was higher O3 deposition and absorption at the forest floor than in the canopy layer; therefore, the understory was an important O3 sink within the forest. A strong NO sink was simulated in the trunk space, where loss by reaction with O3 is expected. The sinks and sources of BVOC as well as their oxidized products are simulated in the canopy layer and the forest floor. The sink and source distribution suggested that VOC transportation from the neighboring forest also affected the vertical sink and source distribution within the canopy.
  • Tomoki Mochizuki, Kimitaka Kawamura, Yuzo Miyazaki, Bhagawati Kunwar, Suresh Kumar Reddy Boreddy
    Atmospheric Chemistry and Physics 19 (4) 2421 - 2432 1680-7316 2019/02 [Refereed][Not invited]
     
    Abstract. To better understand the distributions and sources oflow-molecular-weight (LMW) monocarboxylic acids (monoacids) in the forestatmosphere, we conducted simultaneous collection of gaseous and particulatesamples at a deciduous broadleaf forest site in northern Japan. LMW normal(C1–C10), branched (iC4–iC6), hydroxyl (glycolic andlactic) and aromatic (benzoic) monoacids were detected in the gas andparticle phases. The dominant LMW monoacids in gas phase were formic (mean:953 ng m−3) and acetic (528 ng m−3) acids followed by propionic(37 ng m−3) or isopentanoic (42 ng m−3) acid. In the particlephase, isopentanoic (159 ng m−3) was dominant, followed by acetic(104 ng m−3) and formic (71 ng m−3) or lactic(65 ng m−3) acids. Concentrations of LMW monoacids did not showcorrelations with anthropogenic tracers such as nss-SO42- andNO3-, indicating that anthropogenic contribution is not important.Concentrations of C1–C6 monoacids in the gas phase showed positivecorrelations (r2=0.21–0.91) with isobutyric acid (iC4), whichmay be produced by microbial activity in soil. The forest soil may be asource of gaseous C1–C6 monoacids in the forest atmosphere. Aceticacid in the particle phase positively correlated with nonanoic acid (C9)(r2=0.63), suggesting that formation of acetic and nonanoic acids isassociated with the oxidation of biogenic unsaturated fatty acids in theaerosol phase, in addition to photochemical oxidation of biogenic volatileorganic compounds. The particle-phase fractions (Fp) of formicand acetic acids showed negative correlation with ambient temperature(C1: r2=0.49, C2: r2=0.60) but showed positivecorrelation with relative humidity (C1: r2=0.30, C2: r2=0.55) in daytime, suggesting that these meteorological parameters areimportant for the gas and particle portioning of monoacids in the forestatmosphere.
  • Atmospheric dry deposition of water-soluble nitrogen to the subarctic Western North Pacific Ocean during summer
    Jung, J, B. Han, B. Rodriguez, Y. Miyazaki, H. Y. Chung, K. Kim, J.-O. Choi, K. Park, I.-N. Kim, S. Kim, E. J. Yang, S.-H. Kang
    Atmosphere 10 351  2019 [Refereed][Not invited]
  • Miyazaki, Y, D. Gowda, E. Tachibana, Y. Takahashi, T. Hiura
    Biogeosciences 16 (10) 2181 - 2188 1726-4170 2019 [Refereed][Not invited]
     
    Fatty alcohols (FAs) are major components of surface lipids (waxes) and can act as surface-active organic aerosols in the atmosphere, influencing chemical reactions, particle lifetimes, and the formation of cloud droplets and ice nuclei. However, studies on the composition and source of the FAs in atmospheric aerosols are very limited. In this study, we identified five secondary FAs (SFAs) with C27 and C29 from aerosol samples collected throughout 1 year at two different deciduous forest sites in Japan. Fatty diols, such as n-heptacosan-5,10-diol, were identified in atmospheric aerosols for the first time. Among the identified SFAs, n-nonacosan-10-ol was the most abundant compound, followed by n-nonacosan-5-10-diol at both of the forest sites. Concentrations of the SFAs exhibited distinct seasonal variation, with pronounced peaks during the growing season at each forest site. The SFAs showed significant correlation with sucrose, which is used as a molecular tracer of pollen. A significant fraction of the SFAs was attributed to the submicrometer particles in the growing season. The results indicate that they originated mostly from plant waxes and could be used as useful tracers for primary biological aerosol particles.
  • Kunwar, B, K. Kawamura, S. Fujiwara, P. Fu, Y. Miyazaki, A. Pokhrel
    Atmospheric Research 221 (1) 58 - 71 0169-8095 2019 [Refereed][Not invited]
     
    Aerosol samples were collected at the summit of Mt. Fuji in July-August 2009 and analyzed for diacids and related compounds together with major ions to decipher the sources and formation process of organic aerosols in the free troposphere. Molecular distributions of diacids showed the predominance of oxalic acid (C-2) followed by succinic (C-4) and malonic (C-3) acids. The average concentration of total diacids is ten times higher in whole-day samples than night-only samples due to the uplift of planetary boundary layer in daytime, suggesting the day-time formation of diacids in the uplifted ground-level air mass along the mountain slope. A strong correlation is found between C-4 and levoglucosan in whole-day and nighttime samples. Liquid water content (LWC) shows strong correlations in nighttime with anthropogenic and biogenic secondary organic aerosol (SOA) tracers (e.g., adipic (0.90, p < 0.05) and phthalic acids (0.93, p < 0.05) and 3-methyl 2,3,4-trihydroxy-1-butene (0.95, p < 0.05), suggesting that aqueous-phase chemistry is important for the formation of water-soluble organic aerosols in the free troposphere. In whole-day samples, LWC is strongly correlated with organic carbon (r = 0.97, p < 0.05), and isoprene-SOA tracers such as methylthreitol (0.96, p < 0.05), methylerythritol (0.97, p < 0.05), 2-methylglyceric acid (0.94, p < 0.05) and glycolic acid (0.98, p < 0.05), suggesting that daytime SOAs are mainly from the oxidation of isoprene emitted from the regional forests on the foothill of Mt. Fuji. A strong correlation between LWC and glycolic acid further suggests that isoprene is the main precursor for the production of oxalic acid via glycolic acid as intermediate. This study supports the heterogeneous formation of diacids in the free troposphere.
  • Chemical transfer of dissolved organic matter from surface seawater to sea spray water-soluble organic aerosol in the marine atmosphere
    Yuzo Miyazaki, Youhei Yamashita, Kaori Kawana, Eri Tachibana, Sara Kagami, Michihiro Mochida, Koji Suzuki, Jun Nishioka
    Scientific Reports 8 (1) 14861  2018/10 [Refereed][Not invited]
  • Hygroscopicity of Organic Aerosols and Their Contributions to CCN Concentrations Over a Midlatitude Forest in Japan
    Yange Deng, Sara Kagami, Shuhei Ogawa, Kaori Kawana, Tomoki Nakayama, Ryo Kubodera, Kouji Adachi, Tareq Hussein, Yuzo Miyazaki, Michihiro Mochida
    Journal of Geophysical Research: Atmospheres 2018/09 [Refereed][Not invited]
  • T. Nakayama, Y. Kuruma, Y. Matsumi, Y. Morino, K. Sato, H. Tsurumaru, S. Ramasamy, Y. Sakamoto, S. Kato, Y. Miyazaki, T. Mochizuki, K. Kawamura, Y. Sadanaga, Y. Nakashima, K. Matsuda, Y. Kajii
    ATMOSPHERIC ENVIRONMENT 171 91 - 97 1352-2310 2017/12 [Refereed][Not invited]
     
    As a new approach to investigating formation processes of secondary organic aerosol (SOA) in the atmosphere, ozone-induced potential aerosol formation was measured in summer at a suburban forest site surrounded by deciduous trees, near Tokyo, Japan. After passage through a reactor containing high concentrations of ozone, increases in total particle volume (average of 1.4 x 10(9) nm(3)/cm(3), which corresponds to 17% that of pre-existing particles) were observed, especially during daytime. The observed aerosol formations were compared with the results of box model simulations using simultaneously measured concentrations of gaseous and particulate species. According to the model, the relative contributions of isoprene, monoterpene, and aromatic hydrocarbon oxidation to SOA formation in the reactor were 24, 21, and 55%, respectively. However, the model could explain, on average, only 40% of the observed particle formation, and large discrepancies between the observations and model were found, especially around noon and in the afternoon when the concentrations of isoprene and oxygenated volatile organic compounds were high. The results suggest a significant contribution of missing (unaccounted-for) SOA formation processes from identified and/or unidentified volatile organic compounds, especially those emitted during daytime. Further efforts should be made to explore and parameterize this missing SOA formation to assist in the improvement of atmospheric chemistry and climate models.
  • Tomoki Mochizuki, Kimitaka Kawamura, Yuzo Miyazaki, Ryuichi Wada, Yoshiyuki Takahashi, Nobuko Saigusa, Akira Tani
    ATMOSPHERIC ENVIRONMENT 166 255 - 262 1352-2310 2017/10 [Refereed][Not invited]
     
    To better understand the formation of water-soluble organic aerosols in the forest atmosphere, we measured low molecular weight (LMW) dicarboxylic acids, oxocarboxylic acids, alpha-dicarbonyls, unsaturated fatty acids (UFAs), and water-soluble organic carbon (WSOC) in aerosols from a Larix kaempferi forest located at the northern slope of Mt. Fuji, Japan, in summer 2012. Concentrations of dicarboxylic acids, oxocarboxylic acids, alpha-dicarbonyls, and WSOC showed maxima in daytime. Relative abundance of oxalic acid in LMW dicarboxylic acids was on average 52% and its average concentration was 214 ng m(-3). We found that diurnal and temporal variations of oxalic acid are different from those of isoprene and alpha-pinene, whereas biogenic secondary organic aerosols (BSOAs) derived from isoprene and alpha-pinene showed similar variations with oxalic acid. The mass concentration ratios of oxalic acid/BSOAs were relatively constant, although a large variation in the concentrations of toluene that is an anthropogenic volatile organic compound was observed. These results suggest that formation of oxalic acid is associated with the oxidation of isoprene and alpha-pinene with O-3 and other oxidants in the forest atmosphere. In addition, concentrations of UFAs were observed, for the first time, to decrease dramatically during daytime in the forest. Mass concentration ratios of azelaic acid to UFAs showed a positive correlation with O-3, suggesting that UFAs are oxidized to yield azelaic acid, which may be further decomposed to oxalic acid in the forest atmosphere. We found that contributions of oxalic acid to WSOC are significantly high ranging from 3.7 to 9.7% (average 6.0%). This study demonstrates that forest ecosystem is an important source of oxalic acid and other dicarboxylic acids in the atmosphere. (c) 2017 Elsevier Ltd. All rights reserved.
  • Astrid Mueller, Yuzo Miyazaki, Shankar G. Aggarwal, Yasuyuki Kitamori, Suresh K. R. Boreddy, Kimitaka Kawamura
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 122 (17) 9301 - 9318 2169-897X 2017/09 [Refereed][Not invited]
     
    Ambient hygroscopic properties, numbers of size-segregated cloud condensation nuclei (CCN) at different supersaturations (0.1%-0.8%), and the chemical composition of submicron particles were simultaneously measured at a suburban site in northern Japan in summer. Two distinct periods with different growth factors (GF), CCN activation diameters, and chemical compositions were observed. The data suggest that internally mixed sulfate aerosols dominated the accumulation size mode in relatively aged aerosols during the first period, whereas particles observed during the latter periods showed external mixing dominated by organics, which was linked to low hygroscopicity and CCN activity. In particular, the higher loading of water-soluble organic matter (WSOM; similar to 60% of OM by mass) with increased WSOM/sulfate ratios corresponded to a low hygroscopicity parameter derived from the CCN measurement (kappa(CCN) = 0.15 +/- 0.02) at a dry diameter (D-dry) of 146 nm. The results suggest that WSOM, likely dominated by the influence of biogenic sources, contributed to reducing the hygroscopicity and CCN activation at this particle size. Temporal variations in the number concentrations for low GF mode at D-dry = 49.6 nm were similar to those in the elemental carbon (EC) concentration, suggesting that EC contributed to reducing hygroscopicity at this smaller size. Our results suggest that chemical composition and mixing state are important factors controlling the hygroscopicity and CCN activation of submicron particles. These results provide useful data sets of size-resolved subsaturated and supersaturated hygroscopicity and highlight the importance of the abundance of OM relative to sulfate in predicting the effects on climate change.
  • Astrid Mueller, Yuzo Miyazaki, Eri Tachibana, Kimitaka Kawamura, Tsutom Hiura
    SCIENTIFIC REPORTS 7 8452  2045-2322 2017/08 [Refereed][Not invited]
     
    Biogenic organic aerosols can affect cloud condensation nuclei (CCN) properties, and subsequently impact climate change. Large uncertainties exist in how the difference in the types of terrestrial biogenic sources and the abundance of organics relative to sulfate affect CCN properties. For the submicron water-soluble aerosols collected for two years in a cool-temperate forest in northern Japan, we show that the hygroscopicity parameter kappa(CCN) (0.44 +/- 0.07) exhibited a distinct seasonal trend with a minimum in autumn (kappa(CCN) = 0.32-0.37); these kappa(CCN) values were generally larger than that of ambient particles, including water-insoluble fractions. The temporal variability of kappa(CCN) was controlled by the water-soluble organic matter (WSOM)-to-sulfate ratio (R-2 > 0.60), where the significant reduction of kappa(CCN) in autumn was linked to the increased WSOM/sulfate ratio. Positive matrix factorization analysis indicates that alpha-pinene-derived secondary organic aerosol (SOA) substantially contributed to the WSOM mass (similar to 75%) in autumn, the majority of which was attributable to emissions from litter/soil microbial activity near the forest floor. These findings suggest that WSOM, most likely alpha-pinene SOA, originated from the forest floor can significantly suppress the aerosol CCN activity in cool-temperate forests, which have implications for predicting climate effects by changes in biogenic emissions in future.
  • Gowda Divyavani, Miyazaki Yuzo, Takahashi Yoshiyuki, Hiura Tsutom
    Abstracts of Annual Meeting of the Geochemical Society of Japan 一般社団法人日本地球化学会 64 89 - 89 2017 

  • Nakashima, Y, H. Tsurumaru, R. Sathiyamurthi, Y. Sakamoto, S. Kato, Y. Sadanaga, T. Nakayama, Y. Miyazaki, T. Mochizuki, R. Wada, K. Matsuda, Y. Kajii
    J. Jpn. Soc. Atmos. Environ. 公益社団法人 大気環境学会 52 (6) 167 - 176 1341-4178 2017 [Refereed][Not invited]
     

    Glyoxal is one of the smallest dicarbonyl compounds existing in both the gas phase and in an aerosol. The primary sources of glyoxal have been known to be the photochemical products of the non-methane hydrocarbons. Since the heterogeneous reactions of glyoxal play an important role in the formation of secondary organic aerosols, the studies of the formation process and sources of glyoxal have been reported. However, the reports for the ambient measurements of glyoxal are limited. In this study, the ambient measurements of gaseous glyoxal by incoherent broad band cavity enhanced absorption spectroscopy (IBBCEAS), a novel technique for the measurements of trace species, were carried out in the field museum of Tama hills (FM Tama) maintained and operated by the Tokyo University of Agriculture and Technology during the summer season, July 31–Aug. 7, 2015. During the measurement periods, the average concentration of gaseous glyoxal was 0.24±0.18 ppbv, comparable to the previous measurements in urban areas. From the correlation with gaseous glyoxal and trace species, it is indicated that the sources of glyoxal around the measurement point were photochemical products.

  • Qingcai Chen, Yuzo Miyazaki, Kimitaka Kawamura, Kiyoshi Matsumoto, Sean Coburn, Rainer Volkamer, Yoko Iwamoto, Sara Kagami, Yange Deng, Shuhei Ogawa, Sathiyamurthi Ramasamy, Shungo Kato, Akira Ida, Yoshizumi Kajii, Michihiro Mochida
    ENVIRONMENTAL SCIENCE & TECHNOLOGY 50 (19) 10351 - 10360 0013-936X 2016/10 [Refereed][Not invited]
     
    Chromophoric water-soluble organic matter in atmospheric aerosols potentially plays an important role in aqueous reactions and light absorption by organics. The fluorescence and chemical-structural characteristics of the chromophoric water-soluble organic matter in submicron aerosols collected in urban, forest, and marine environments (Nagoya, Kii Peninsula, and the tropical Eastern Pacific) were investigated using excitation emission matrices (EEMs) and a high-resolution aerosol mass spectrometer. A total of three types of water-soluble chromophores, two with fluorescence characteristics similar to those of humiclike substances (HULIS-1 and HULIS-2) and one with fluorescence characteristics similar to those of protein compounds (PLOM), were identified in atmospheric aerosols by parallel factor analysis (PARAFAC) for EEMs. We found that the chromophore components of HULIS-1 and -2 were associated with highly and less-oxygenated structures, respectively, which may provide a clue to understanding the chemical formation or loss of organic chromophores in atmospheric aerosols. Whereas HULIS-1 was ubiquitous in water-soluble chromophores over different environments, HULIS-2 was abundant only in terrestrial aerosols, and PLOM was abundant in marine aerosols. These findings are useful for further studies regarding the classification and source identification of chromophores in atmospheric aerosols.
  • Tatsuhiro Mori, Nobuhiro Moteki, Sho Ohata, Makoto Koike, Kumiko Goto-Azuma, Yuzo Miyazaki, Yutaka Kondo
    AEROSOL SCIENCE AND TECHNOLOGY 50 (3) 242 - 254 0278-6826 2016/03 [Refereed][Not invited]
     
    We developed an improved technique for measuring the size distribution of black carbon (BC) particles suspended in liquid water to facilitate quantitative studies of the wet deposition of BC. The measurement system, which consists of a nebulizer and a single-particle soot photometer, incorporates two improvements into the system that we developed earlier. First, we extended the upper limit of the detectable BC size from 0.9m to about 4.0m by modifying the photo-detector for measuring the laser-induced incandescence signal. Second, we introduced a pneumatic nebulizer (Marin-5) with a high extraction efficiency (approximate to 50.0%) that was independent of particle diameter up to 2.0m. For BC mass concentrations less than 70g L-1, we experimentally showed that the diameters of BC particles did not appreciably change during the Marin-5 extraction process, consistent with theoretical calculations. Finally, we demonstrated by laboratory experiments that the size distributions of ambient BC particles changed little during their growth into cloud droplets under supersaturation of water vapor. Using our improved system, we measured the size distributions of BC particles simultaneously in air and rainwater in Tokyo during summer 2014. We observed that the size distributions of BC particles in rainwater shifted to larger sizes compared with those observed in ambient air, indicating that larger BC particles in air were removed more efficiently by precipitation.Copyright (c) 2016 American Association for Aerosol Research
  • Miyazaki Yuzo, Coburn Sean, Muller Astrid, Ono Kaori, T. Ho David, Bradley Pierce R., Kawamura Kimitaka, Volkamer Rainer
    Abstracts of Annual Meeting of the Geochemical Society of Japan 日本地球化学会 63 96 - 96 2016 

  • Yuzo Miyazaki, Sean Coburn, Kaori Ono, David T. Ho, R. Bradley Pierce, Kimitaka Kawamura, Rainer Volkamer
    ATMOSPHERIC CHEMISTRY AND PHYSICS 16 (12) 7695 - 7707 1680-7316 2016 [Refereed][Not invited]
     
    Stable carbon isotopic compositions of water-soluble organic carbon (WSOC) and organic molecular markers were measured to investigate the relative contributions of the sea surface sources to the water-soluble fraction of submicron organic aerosols collected over the eastern equatorial Pacific during the Tropical Ocean tRoposphere Exchange of Reactive halogens and Oxygenated VOCs (TORERO)/KA-12-01 cruise. On average, the water-soluble organic fraction of the total carbon (TC) mass in submicron aerosols was similar to aEuro-30-35aEuro-% in the oceans with the low chlorophyll a (Chl a) concentrations, whereas it was similar to aEuro-60aEuro-% in the high-Chl a regions. The average stable carbon isotope ratio of WSOC (delta C-13(WSOC)) was -19.8aEuro-+/- aEuro-2.0aEuro-aEuro degrees, which was systematically higher than that of TC (delta C-13(TC)) (-21.8aEuro-+/- aEuro-1.4aEuro-aEuro degrees). We found that in the oceans with both high and low Chl a concentrations the delta C-13(WSOC) was close to the typical values of delta C-13 for dissolved organic carbon (DOC), ranging from -22 to -20aEuro-aEuro degrees in surface seawater of the tropical Pacific Ocean. This suggests an enrichment of marine biological products in WSOC aerosols in the study region regardless of the oceanic area. In particular, enhanced levels of WSOC and biogenic organic marker compounds together with high values of WSOCaEuro-/aEuro-TC ( similar to aEuro-60aEuro-%) and delta C-13(WSOC) were observed over upwelling areas and phytoplankton blooms, which was attributed to planktonic tissues being more enriched in delta C-13. The delta C-13 analysis estimated that, on average, marine sources contribute similar to aEuro-90aEuro-+/- aEuro-25aEuro-% of the aerosol carbon, indicating the predominance of marine-derived carbon in the submicron WSOC. This conclusion is supported by Lagrangian trajectory analysis, which suggests that the majority of the sampling points on the ship had been exposed to marine boundary layer (MBL) air for more than 80aEuro-% of the time during the previous 7 days. The combined analysis of the delta C-13 and monosaccharides, such as glucose and fructose, demonstrated that DOC concentration was closely correlated with the concentration levels of submicron WSOC across the study region regardless of the oceanic area. The result implies that DOC may characterize background organic aerosols in the MBL over the study region.
  • Yoko Yokouchi, Akio Takenaka, Yuzo Miyazaki, Kimitaka Kawamura, Tsutom Hiura
    JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES 120 (6) 1142 - 1149 2169-8953 2015/06 [Refereed][Not invited]
     
    Tropical and subtropical forests are believed to be the largest source of methyl chloride (CH3Cl), which is a natural stratospheric ozone destroyer. However, very little is known about what controls the rate of emission from these forests or why biogenic CH3Cl emission is concentrated in the tropics and subtropics. In this study, we investigated the seasonal and spatial variations of the rate of CH3Cl emission from the fern Osmunda japonica, which has a broad distribution covering the subtropical, temperate, and subboreal climate zones. The average rates of CH3Cl emission from the fern were similar (1-4 mu gg(dw)(-1)h(-1)) among three areas, and there was no significant seasonal change in the temperate zone, although the rate was highly variable among individual plants. These findings suggest that meteorological climate such as temperature and solar radiation is not a major environmental factor controlling biogenic CH3Cl emission of individual plants, but species with high CH3Cl emission activity are more abundant in tropical and subtropical zones. We also found that developmental stage might be an important factor controlling biogenic CH3Cl emission rates. These results have implications for predicting future global CH3Cl emission budgets and for understanding of the plant-atmosphere interaction.
  • Srinivas Bikkina, Kimitaka Kawamura, Yuzo Miyazaki
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 120 (10) 5010 - 5035 2169-897X 2015/05 [Refereed][Not invited]
     
    The present study aims to assess the molecular distributions of water-soluble dicarboxylic acids (diacids: C-2-C-12), oxocarboxylic acids (C-2-C-9), and -dicarbonyls (glyoxal and methylglyoxal) in aerosols collected over the western North Pacific (WNP) during a summer cruise (August to September 2008). The measured water-soluble organics show pronounced latitudinal distributions with higher concentrations in the region of 30 degrees N-45 degrees N (average 63ngm(-3)) than 10 degrees N-30 degrees N (18ngm(-3)). Mass fraction of oxalic acid (C-2) in total aliphatic diacids (sigma C-2-C-12) showed higher values (7210%) in lower latitude (10 degrees N-30 degrees N) than that (5616%) in higher latitude (30 degrees N-45 degrees N), suggesting a photochemical production of C-2 due to an increased insolation over the tropical WNP. A similar trend was found in other diagnostic ratios such as oxalic to succinic (C-2/C-4) and oxalic to glyoxylic acid (C-2/C-2), which further corroborate an enhanced photochemical aging over the WNP. In addition, relative abundances of oxalic acid in total diacids showed a marked increase as a function of ambient temperature, supporting their photochemical production. Constantly low concentration ratios of adipic and phthalic acids relative to azelaic acid suggest a small contribution of anthropogenic sources and an importance of oceanic sources during the study period. Significant production of C-2 through oxidation of biogenic volatile organic compounds emitted from the sea surface is also noteworthy, as inferred from the strong linear correlations among water-soluble organic carbon, methanesulphonic acid, and oxalic acid. Sea-to-air emission of unsaturated fatty acids also contributes to formation of diacids over the WNP.
  • Srinivas Bikkina, Kimitaka Kawamura, Yuzo Miyazaki
    Journal of Geophysical Research 120 (10) 5010 - 5035 2156-2202 2015 [Refereed][Not invited]
     
    The present study aims to assess the molecular distributions of water-soluble dicarboxylic acids (diacids: C2–C12), oxocarboxylic acids (C2–C9), and α-dicarbonyls (glyoxal and methylglyoxal) in aerosols collected over the western North Pacific (WNP) during a summer cruise (August to September 2008). The measured water-soluble organics show pronounced latitudinal distributions with higher concentrations in the region of 30°N–45°N (average 63 ngm-3) than 10°N–30°N (18 ngm-3). Mass fraction of oxalic acid (C2) in total aliphatic diacids (ΣC2–C12) showed higher values (72 ± 10%) in lower latitude (10°N–30°N) than that (56 ± 16%) in higher latitude (30°N–45°N), suggesting a photochemical production of C2 due to an increased insolation over the tropical WNP. A similar trend was found in other diagnostic ratios such as oxalic to succinic (C2/C4) and oxalic to glyoxylic acid (C2/ωC2), which further corroborate an enhanced photochemical aging over the WNP. In addition, relative abundances of oxalic acid in total diacids showed a marked increase as a function of ambient temperature, supporting their photochemical production. Constantly low concentration ratios of adipic and phthalic acids relative to azelaic acid suggest a small contribution of anthropogenic sources and an importance of oceanic sources during the study period. Significant production of C2 through oxidation of biogenic volatile organic compounds emitted from the sea surface is also noteworthy, as inferred from the strong linear correlations among water-soluble organic carbon, methanesulphonic acid, and oxalic acid. Sea-to-air emission of unsaturated fatty acids also contributes to formation of diacids over the WNP.
  • T. Mochizuki, Y. Miyazaki, K. Ono, R. Wada, Y. Takahashi, N. Saigusa, K. Kawamura, A. Tani
    ATMOSPHERIC CHEMISTRY AND PHYSICS 15 (20) 12029 - 12041 1680-7316 2015 [Refereed][Not invited]
     
    We conducted simultaneous measurements of concentrations and above-canopy fluxes of isoprene and alpha-pinene, along with their oxidation products in aerosols in a Larix kaempferi (Japanese larch) forest in summer 2012. Vertical profiles of isoprene showed the maximum concentration near the forest floor with a peak around noon, whereas oxidation products of isoprene, i.e., methacrolein (MACR) and methyl vinyl ketone (MVK), showed higher concentrations near the canopy level of the forest. The vertical profile suggests large emissions of isoprene near the forest floor, likely due to Dryopteris crassirhizoma (a fern species), and the subsequent reaction within the canopy. The concentrations of alpha-pinene also showed highest values near the forest floor, with maximums in the early morning and late afternoon. The vertical profiles of alpha-pinene suggest its large emissions from soil and litter in addition to emissions from L. kaempferi leaves at the forest site. Isoprene and its oxidation products in aerosols exhibited similar diurnal variations within the forest canopy, providing evidence of secondary organic aerosol (SOA) formation via oxidation of isoprene most likely emitted from the forest floor. Although high abundance of alpha-pinene was observed in the morning, its oxidation products in aerosols showed peaks in daytime, due to a time lag between the emission and atmospheric reactions of alpha-pinene to form SOA. Positive matrix factorization (PMF) analysis indicated that anthropogenic influence is the most important factor contributing to the elevated concentrations of molecular oxidation products of isoprene- (> 64 %) and alpha-pinene-derived SOA (> 57 %). The combination of the measured fluxes and vertical profiles of biogenic volatile organic compounds ( BVOCs) suggests that the inflow of anthropogenic precursors/aerosols likely enhanced the formation of both isoprene SOA and alpha-pinene SOA within the forest canopy even when the BVOC flux was relatively low. This study highlights the importance of intra-canopy processes that promote biogenic SOA formation in the presence of significant inflow of oxidants together with anthropogenic aerosols and their precursors.
  • Pingqing Fu, Kimitaka Kawamura, Jing Chen, Yuzo Miyazaki
    ENVIRONMENTAL SCIENCE & TECHNOLOGY 48 (15) 8491 - 8497 0013-936X 2014/08 [Refereed][Not invited]
     
    We investigated organic molecular compositions of summertime aerosols collected at the summit of Mt. Fuji (3776 m a.s.l.) in July-August 2009. More than 120 organic species were identified using GC/MS. Concentrations of both primary and secondary organic aerosol (SOA) tracers in whole-day samples were 4-20 times higher than those in nighttime samples, suggesting that valley breeze is an efficient mechanism to uplift the aerosols and precursors from the ground surface to mountaintop in daytime. Using a tracer-based method, we estimated the concentrations of secondary organic carbon (SOC) derived from isoprene, alpha/beta-pinene, and beta-caryophyllene to be 2.2-51.2 ngC m(-3) in nighttime and 227-1120 ngC m(-3) during whole-day. These biogenic SOCs correspond to 0.80-31.9% and 26.8-57.4% of aerosol organic carbon in nighttime and whole-day samples, respectively. This study demonstrates that biogenic SOA, which is controlled by the valley breeze, is a significant fraction of free tropospheric aerosols over Mt. Fuji in summer.
  • Srinivas Bikkina, Kimitaka Kawamura, Yuzo Miyazaki, Pingqing Fu
    GEOPHYSICAL RESEARCH LETTERS 41 (10) 3649 - 3657 0094-8276 2014/05 [Refereed][Not invited]
     
    Atmospheric dicarboxylic acids (DCA) are a ubiquitous water-soluble component of secondary organic aerosols (SOA), which can act as cloud condensation nuclei (CCN), affecting the Earth's climate. Despite the high abundances of oxalic acid and related compounds in the marine aerosols, there is no consensus on what controls their distributions over the open ocean. Marine biological productivity could play a role in the production of DCA, but there is no substantial evidence to support this hypothesis. Here we present latitudinal distributions of DCA, oxoacids and -dicarbonyls in the marine aerosols from the remote Pacific. Their concentrations were found several times higher in more biologically influenced aerosols (MBA) than less biologically influenced aerosols. We propose isoprene and unsaturated fatty acids as sources of DCA as inferred from significantly higher abundances of isoprene-SOA tracers and azelaic acid in MBA. These results have implications toward the reassessment of climate forcing feedbacks of marine-derived SOA.
  • Yuzo Miyazaki, PingQing Fu, Kaori Ono, Eri Tachibana, Kimitaka Kawamura
    Journal of Geophysical Research 119 (3) 1440 - 1454 2156-2202 2014/02/16 [Refereed][Not invited]
     
    The seasonal variations in aerosol water-soluble organic nitrogen (WSON) concentrations measured in a deciduous forest canopy over an approximately 30 month period were investigated for possible sources in the forest. The WSON concentrations (average 157 ± 127 ng N m-3) and WSON/water-soluble total nitrogen mass fractions (average 20 ± 11%) in the total suspended particulate matter exhibited a clear seasonal cycle with maxima in early summer. The WSON mass was found to reside mostly in the fine-mode size range (Dp < 1.9 μm) during the summer months. WSON was positively correlated with oxidation products of α-pinene and isoprene with similar size distributions, suggesting that secondary formation from biogenic hydrocarbon precursors is a plausible source for WSON in summer. In contrast, the majority of WSON in autumn was associated with coarse fraction (Dp > 1.9 μm), which was similar to the size distributions of sugar compounds, indicating that the major WSON sources in autumn are associated with primary biological emissions. The vertical differences in WSON concentrations suggest that the water-soluble organic aerosol is enriched with nitrogen below the canopy level relative to the forest floor. The WSON concentration increased with enhanced hydrogen ion concentrations in aerosol in the early summer, indicating that aerosol acidity associated with anthropogenic sources outside the forest likely plays an important role in the formation of WSON in that season. The study suggests that multiple sources of WSON within the forest canopy may dominate over others in specific seasons, providing insights into WSON formation processes in forest environments.
  • Yuzo Miyazaki, PingQing Fu, Kaori Ono, Eri Tachibana, Kimitaka Kawamura
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 119 (3) 1440 - 1454 2169-897X 2014/02 [Refereed][Not invited]
     
    The seasonal variations in aerosol water-soluble organic nitrogen (WSON) concentrations measured in a deciduous forest canopy over an approximately 30month period were investigated for possible sources in the forest. The WSON concentrations (average 157 +/- 127 ng N m(-3)) and WSON/water-soluble total nitrogen mass fractions (average 20 +/- 11%) in the total suspended particulate matter exhibited a clear seasonal cycle with maxima in early summer. The WSON mass was found to reside mostly in the fine-mode size range (D-p < 1.9 mu m) during the summer months. WSON was positively correlated with oxidation products of -pinene and isoprene with similar size distributions, suggesting that secondary formation from biogenic hydrocarbon precursors is a plausible source for WSON in summer. In contrast, the majority of WSON in autumn was associated with coarse fraction (D-p > 1.9 mu m), which was similar to the size distributions of sugar compounds, indicating that the major WSON sources in autumn are associated with primary biological emissions. The vertical differences in WSON concentrations suggest that the water-soluble organic aerosol is enriched with nitrogen below the canopy level relative to the forest floor. The WSON concentration increased with enhanced hydrogen ion concentrations in aerosol in the early summer, indicating that aerosol acidity associated with anthropogenic sources outside the forest likely plays an important role in the formation of WSON in that season. The study suggests that multiple sources of WSON within the forest canopy may dominate over others in specific seasons, providing insights into WSON formation processes in forest environments.
  • Y. Miyazaki, M. Sawano, K. Kawamura
    BIOGEOSCIENCES 11 (16) 4407 - 4414 1726-4170 2014 [Refereed][Not invited]
     
    Lactic acid (LA) and glycolic acid (GA), which are low-molecular-weight hydroxyacids, were identified in the particle and gas phases within the marine atmospheric boundary layer over the western subarctic North Pacific. A major portion of LA (81%) and GA (57%) was present in the particulate phase, which is consistent with the presence of a hydroxyl group in these molecules leading to the low volatility of the compounds. The average concentration (+/- SD) of LA in more biologically influenced marine aerosols (33 +/- 58 ng m(-3)) was substantially higher than that in less biologically influenced aerosols (11 +/- 12 ng m(-3)). Over the oceanic region of phytoplankton blooms, the concentration of aerosol LA was comparable to that of oxalic acid, which was the most abundant diacid during the study period. A positive correlation was found between the LA concentrations in more biologically influenced aerosols and chlorophyll a in seawater (r(2) = 0.56), suggesting an important production of aerosol LA possibly associated with microbial (e.g., lactobacillus) activity in seawater and/or aerosols. Our finding provides a new insight into the poorly quantified microbial sources of marine organic aerosols (OAs) because such low-molecular-weight hydroxyacids are key intermediates for OA formation.
  • J. Jung, Y. Miyazaki, K. Kawamura
    ATMOSPHERIC CHEMISTRY AND PHYSICS 13 (1) 51 - 68 1680-7316 2013 [Refereed][Not invited]
     
    To investigate new particle formation (NPF) events in urban and forest environments, number size distributions of ultrafine particles were measured at an urban site and a deciduous forest site in Sapporo, Northern Japan, during the summers of 2011 and 2010, respectively. The burst of nucleation mode particles at the urban site typically started in the morning (07:00-11:30 local time, LT) with simultaneous increases in SO2 and O-3 concentrations and the UV index under clear (sunny) weather conditions. The growth rates of nucleated particles at the urban site ranged from 5.0 to 7.8 nm h(-1) with an average of 6.3 +/- 1.1 nm h(-1). NPF events at the urban site were separated into events with or without subsequent particle growth after the burst of nucleation mode particles. This division was found to relate to prevailing wind direction because the subsequent growth of freshly nucleated particles typically occurred when wind direction shifted to northwesterly (from residential and public park areas), whereas it did not occur under southeasterly winds (from the downtown area). During the periods with NPF events, elevated concentrations of non-methane hydrocarbons (NMHC) were obtained under conditions of northwesterly winds when compared to southeasterly winds, whereas no difference in SO2 levels was recorded. These results suggest that variations in NMHC concentration may play an important role in the growth of freshly nucleated particles at the urban site. The burst of nucleation mode particles at the forest site typically started around noon (10:30-14:30 LT), which was 3-4 h later than that at the urban site. Interestingly, at the forest site the burst of nucleation mode particles usually started when air masses originating from urban Sapporo arrived at the forest site. The present study indicates that the inflow of these urban air masses acted as a trigger for the initiation of the burst of nucleation mode particles in the deciduous forest.
  • Yuzo Miyazaki, Jinsang Jung, Pingqing Fu, Yasuko Mizoguchi, Katsumi Yamanoi, Kimitaka Kawamura
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 117 (D19213) doi:10.1029/ 2012JD018250  2169-897X 2012/10 [Refereed][Not invited]
     
    Semicontinuous measurements of submicrometer water-soluble organic aerosols and particle size distributions were conducted at a deciduous forest site in northern Japan in August 2010. Increases in particle number concentration were frequently observed in daytime, accompanied by an increase in the concentrations of water-soluble organic carbon (WSOC). We found that daily averaged WSOC concentrations positively correlated with gross primary production of CO2 by the forest ecosystem (r(2) = 0.63) and ambient temperature during daytime. These relations suggest that the formation of WSOC is closely linked to photosynthetic activity by the forest ecosystem, which depends on both temperature and solar radiation. Off-line chemical analysis of samples of particles with aerodynamic diameter smaller than 1 mu m collected during a 2 day event of elevated WSOC levels suggests that photochemical aging of both alpha- and beta-pinene and isoprene oxidation products contributes to the particle growth and the WSOC mass. Organic tracers of primary biological aerosol particles (PBAPs) showed distinct diurnal variations with a maximum around noontime, also indicating that higher temperature and light intensity induce emissions of PBAPs. However, their contribution to the submicrometer WSOC mass was likely insignificant. During the day, the concentrations of 3-methyl-1,2,3-butanetricarboxylic acid (3-MBTCA) showed a strong dependence on temperature, and the ratios of WSOC to particle volume concentration increased with an increase in the concentration ratios of 3-MBTCA to pinonic acid (PA). This result supports a previous proposal that the 3-MBTCA/PA ratios in submicrometer particles can be a useful tracer for chemical aging of biogenic secondary organic aerosol from forest vegetation.
  • MIYAZAKI Yuzo
    Earozoru Kenkyu 日本エアロゾル学会 27 (1) 24 - 33 0912-2834 2012/03 [Refereed][Invited]
     
    Over the past decade, considerable progress has been made in understanding sources and formation processes of water-soluble organic aerosol (OA) in the atmosphere. This review article discusses the current knowledge on chemical characteristics, formation processes, and physical properties of water-soluble OA. In particular, organic aerosols formed in cloud and aerosol water are suggested to contribute substantially to OA mass. The review emphasizes the important roles of water-soluble organics in secondary OA formation including aqueous-phase reactions through field and laboratory studies.
  • MIYAZAKI Yuzo
    天気 日本気象学会 59 (1) 23 - 32 0546-0921 2012/01 [Refereed][Invited]
  • Y. Miyazaki, P. Q. Fu, K. Kawamura, Y. Mizoguchi, K. Yamanoi
    ATMOSPHERIC CHEMISTRY AND PHYSICS 12 (3) 1367 - 1376 1680-7316 2012 [Refereed][Not invited]
     
    To investigate the seasonal changes in biogenic water-soluble organic carbon (WSOC) aerosols in a boreal forest, aerosol samples were collected continuously in the canopy of a deciduous forest in northern Japan during 2009-2010. Stable carbon isotopic composition of WSOC (delta C-13(WSOC)) in total suspended particulate matter (TSP) exhibited a distinct seasonal cycle, with lower values from June through September (-25.5 +/- 0.5 parts per thousand). This cycle follows the net CO2 exchange between the forest ecosystem and the atmosphere, indicating that delta C-13(WSOC) likely reflects the biological activity at the forest site. WSOC concentrations showed the highest values in early summer and autumn. Positive matrix factorization (PMF) analysis indicated that the factor in which biogenic secondary organic aerosols (BSOAs) dominated accounted for similar to 40% of the highest concentrations of WSOC, where BSOAs mostly consisted of alpha-/beta-pinene SOA. In addition, primary biological aerosol particles (PBAPs) made similar contributions (similar to 57 %) to the WSOC near the forest floor in early summer. This finding indicates that the production of both primary and secondary WSOC aerosols is important during the growing season in a deciduous forest. The methanesulfonic acid (MSA) maximum was also found in early summer and had a distinct vertical gradient with larger concentrations near the forest floor. Together with the similar vertical gradients found for WSOC and delta C-13(WSOC) as well as the alpha-/beta-pinene SOA tracers, our results indicate that the forest floor, including ground vegetation and soil, acts as a significant source of WSOC in TSP within a forest canopy at the study site.
  • Yuzo Miyazaki, Jinsang Jung, Pingqing Fu, Yasuko Mizoguchi, Katsumi Yamanoi, Kimitaka Kawamura
    Journal of Geophysical Research Atmospheres 117 (19) 0148-0227 2012 [Refereed][Not invited]
     
    Semicontinuous measurements of submicrometer water-soluble organic aerosols and particle size distributions were conducted at a deciduous forest site in northern Japan in August 2010. Increases in particle number concentration were frequently observed in daytime, accompanied by an increase in the concentrations of water-soluble organic carbon (WSOC). We found that daily averaged WSOC concentrations positively correlated with gross primary production of CO < inf> 2< /inf> by the forest ecosystem (r< sup> 2< /sup> =0.63) and ambient temperature during daytime. These relations suggest that the formation of WSOC is closely linked to photosynthetic activity by the forest ecosystem, which depends on both temperature and solar radiation. Off-line chemical analysis of samples of particles with aerodynamic diameter smaller than 1m collected during a 2day event of elevated WSOC levels suggests that photochemical aging of both-and-pinene and isoprene oxidation products contributes to the particle growth and the WSOC mass. Organic tracers of primary biological aerosol particles (PBAPs) showed distinct diurnal variations with a maximum around noontime, also indicating that higher temperature and light intensity induce emissions of PBAPs. However, their contribution to the submicrometer WSOC mass was likely insignificant. During the day, the concentrations of 3-methyl-1,2,3-butanetricarboxylic acid (3-MBTCA) showed a strong dependence on temperature, and the ratios of WSOC to particle volume concentration increased with an increase in the concentration ratios of 3-MBTCA to pinonic acid (PA). This result supports a previous proposal that the 3-MBTCA/PA ratios in submicrometer particles can be a useful tracer for chemical aging of biogenic secondary organic aerosol from forest vegetation. © 2012. American Geophysical Union. All Rights Reserved.
  • L. K. Sahu, Y. Kondo, Y. Miyazaki, Prapat Pongkiatkul, N. T. Kim Oanh
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 116 (D15302) doi:10.1029/2010JD015563  2169-897X 2011/08 [Refereed][Not invited]
     
    Measurements of black carbon (BC) and organic carbon (OC) were conducted in Bangkok during 2007-2008. Annual trends of BC and OC show strong seasonality with lower and higher concentrations during wet and dry seasons, respectively. Flow of cleaner air, wet removal, and negligible biomass burning resulted in the lowest concentrations of aerosols in the wet season. In addition to anthropogenic sources, long-range transport and biomass burning caused higher concentrations in the dry and hot seasons, respectively. Despite extensive biomass burning in the hot season, moderate levels of aerosols were due to the mixing with air masses from the Pacific Ocean. Diurnal distributions exhibit peaks during rush hour marked by minima in the OC/BC ratio and stagnant wind flow. The lowest concentrations in the afternoon hours could be due to deeper planetary boundary layer and reduced traffic. Overall, the concentrations of both BC and OC decrease with the increase in wind speed. The weekend effects, due to reduced emission during weekends, in the concentrations of both BC and OC were significant. Therefore, stricter abatement in vehicular emissions could substantially reduce pollution. A slope of Delta BC/Delta CO of 9.8 ngm(-3) ppbv(-1) for the wet season represents the emission ratio from vehicular sources. The highest of Delta OC/Delta BC (3 mu g mu g(-1)) in the hot season was due to the predominant influence of biomass burning and significant formation of secondary OC. The levels of BC and OC in Bangkok fall within the ranges of their concentrations measured in the major cities of East Asia.
  • Michihiro Mochida, Chiharu Nishita-Hara, Hiroshi Furutani, Yuzo Miyazaki, Jinyoung Jung, Kimitaka Kawamura, Mitsuo Uematsu
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 116 (D06204) doi:10.1029/2010JD014759  2169-897X 2011/03 [Refereed][Not invited]
     
    Hygroscopic growth of aerosol particles at 85% relative humidity and the number fraction of cloud condensation nuclei (CCN; 0.42%, 0.23%, and 0.10% supersaturation) as a function of dry diameter (24.1-359 nm) were measured simultaneously on board R/V Hakuho-Maru over the western North Pacific during August-September 2008. Highly hygroscopic and unimodal growth distributions were observed, except for aerosols, which showed lower hygroscopic growth over the northern Pacific. The measured particle hygroscopicity, CCN activation diameters, and chemical composition data suggest the dominance of internally mixed sulfate aerosols. Backward air mass trajectory analysis exhibits an intrusion of free tropospheric aerosol, which was likely influenced by Kasatochi's volcanic plume and which was linked to the low-hygroscopicity event. Frequent observation of the Hoppel minimum suggests that in-cloud processing over the Pacific enhanced and/or maintained the high hygroscopicity of accumulation mode particles. The CCN activation diameters predicted from median hygroscopic growth factors (g(median)) agreed well with those determined from the CCN efficiency spectra, without assuming surface tension reduction caused by organics or enhancement of bulk hygroscopicity at high RH caused by sparingly soluble or polymeric compounds. The CCN spectra predicted from gmedian and measured CCN activation diameters suggest that the high CCN activities of particles over the North Pacific are sustained by high hygroscopicity, while sporadic changes of aerosol origins produce the diversity of the aerosol properties.
  • R. Xiao, N. Takegawa, M. Zheng, Y. Kondo, Y. Miyazaki, T. Miyakawa, M. Hu, M. Shao, L. Zeng, Y. Gong, K. Lu, Z. Deng, Y. Zhao, Y. H. Zhang
    ATMOSPHERIC CHEMISTRY AND PHYSICS 11 (14) 6911 - 6929 1680-7316 2011 [Refereed][Not invited]
     
    Size-resolved chemical compositions of non-refractory submicron aerosol were measured using an Aerodyne quadrupole aerosol mass spectrometer (Q-AMS) at the rural site Back Garden (BG), located similar to 50 km northwest of Guangzhou in July 2006. This paper characterized the submicron aerosol particles of regional air pollution in Pearl River Delta (PRD) in the southern China. Organics and sulfate dominated the submicron aerosol compositions, with average mass concentrations of 11.8 +/- 8.4 mu gm(-3) and 13.5 +/- 8.7 mu gm(-3), respectively. Unlike other air masses, the air masses originated from Southeast-South and passing through the PRD urban areas exhibited distinct bimodal size distribution characteristics for both organics and sulfate: the first mode peaked at vacuum aerodynamic diameters (D(va)) similar to 200 nm and the second mode occurred at Dva from 300-700 nm. With the information from AMS, it was found from this study that the first mode of organics in PRD regional air masses was contributed by both secondary organic aerosol formation and combustion-related emissions, which is different from most findings in other urban areas (first mode of organics primarily from combustion-related emissions). The analysis of AMS mass spectra data by positive matrix factorization (PMF) model identified three sources of submicron organic aerosol including hydrocarbon-like organic aerosol (HOA), low volatility oxygenated organic aerosol (LV-OOA) and semi-volatile oxy-genated organic aerosol (SV-OOA). The strong correlation between HOA and EC indicated primary combustion emissions as the major source of HOA while a close correlation between SV-OOA and semi-volatile secondary species nitrate as well as between LV-OOA and nonvolatile secondary species sulfate suggested secondary aerosol formation as the major source of SV-OOA and LV-OOA at the BG site. However, LV-OOA was more aged than SV-OOA as its spectra was highly correlated with the reference spectra of fulvic acid, an indicator of aged and oxygenated aerosol. The origin of HOA and OOA (the sum of LV-OOA and SV-OOA) has been further confirmed by the statistics that primary organic carbon (POC) and secondary organic carbon (SOC), estimated by the EC tracer method, were closely correlated with HOA and OOA, respectively. The results of the EC tracer method and of the PMF model revealed that primary organic aerosol (POA) constituted similar to 34-47% of OA mass and secondary organic aerosol (SOA) constituted similar to 53-66% of regional organic aerosol in PRD during summer season. The presence of abundant SOA was consistent with water soluble organic carbon (WSOC) results (accounting for similar to 60% of OC on average) by Miyazaki et al. (2009) for the same campaign. OOA correlated well with WSOC at the BG site, indicating that most OOA were water soluble. More specifically, approximately 86% of LV-OOA and 61% of SV-OOA were estimated as water soluble species on the basis of carbon content comparison.
  • Y. Miyazaki, K. Kawamura, J. Jung, H. Furutani, M. Uematsu
    ATMOSPHERIC CHEMISTRY AND PHYSICS 11 (7) 3037 - 3049 1680-7316 2011 [Not refereed][Not invited]
     
    Marine aerosol samples were collected over the western North Pacific along the latitudinal transect from 44 degrees N to 10 degrees N in late summer 2008 for measurements of organic nitrogen (ON) and organic carbon (OC) as well as isotopic ratios of total nitrogen (TN) and total carbon (TC). Increased concentrations of methanesulfonic acid (MSA) and diethylammonium (DEA(+)) at 40-44 degrees N and subtropical regions (10-20 degrees N) together with averaged satellite chlorophyll-a data and 5-day back trajectories suggest a significant influence of marine biological activities on aerosols in these regions. ON exhibited increased concentrations up to 260 ngN m(-3) in these marine biologically influenced aerosols. Water-insoluble organic nitrogen (WION) was found to be the most abundant nitrogen in the aerosols, accounting for 55 +/- 16% of total aerosol nitrogen. In particular, the average WION/ON ratio was as high as 0.93 +/- 0.07 at 40-14 degrees N. These results suggest that marine biological sources significantly contributed to ON, a majority of which is composed of water-insoluble fractions in the study region. Analysis of the stable carbon isotopic ratios (delta C-13) indicated that, on average, marine-derived carbon accounted for similar to 88 +/- 12% of total carbon in the aerosols. In addition, the delta C-13 showed higher values (from -22 to 20 parts per thousand) when ON/OC ratios increased from 0.15 to 0.35 in marine biologically influenced aerosols. These results clearly show that organic nitrogen is enriched in organic aerosols originated from an oceanic region with high biological productivity, indicating a preferential transfer of nitrogen-containing organic compounds from the sea surface to the marine atmosphere. Both WION concentrations and WION/water-insoluble organic carbon (WIOC) ratios tended to increase with increasing local wind speeds, indicating that sea-to-air emissions of ON via sea spray contribute significantly to the marine organic aerosols over the study region.
  • Miyazaki Yuzo, Fu PingQing, Kawamura Kimitaka, Yamanoi Katsumi
    Abstracts of Annual Meeting of the Geochemical Society of Japan 日本地球化学会 58 28 - 28 2011 
    北方森林生態系における水溶性有機エアロゾルの主要な発生源を明らかにすることを目的とし、落葉広葉樹演習林の観測タワーで約1年半以上にわたり採取した大気エアロゾルサンプルを用いて水溶性有機炭素（WSOC）とその安定炭素同位体比（δ13C-WSOC）の測定を行なった。δ13C-WSOCは、初夏から秋季にかけて値が減少する明瞭な季節変化を示し、純生態系CO2交換量との相関からWSOCへの森林植生寄与を表す指標として有用であることが示唆された。WSOC濃度や植生起源有機物トレーサーの季節変動や鉛直勾配から、森林植生の成長期である初夏を中心に地表付近の植生や土壌を含む林床が森林キャノピー層内における水溶性有機エアロゾルの発生源として重要であることが示唆された。
  • L. K. Sahu, Y. Kondo, Y. Miyazaki, Prapat Pongkiatkul, N. T. Kim Oanh
    Journal of Geophysical Research Atmospheres 116 (15) 0148-0227 2011 [Refereed][Not invited]
     
    Measurements of black carbon (BC) and organic carbon (OC) were conducted in Bangkok during 2007-2008. Annual trends of BC and OC show strong seasonality with lower and higher concentrations during wet and dry seasons, respectively. Flow of cleaner air, wet removal, and negligible biomass burning resulted in the lowest concentrations of aerosols in the wet season. In addition to anthropogenic sources, long-range transport and biomass burning caused higher concentrations in the dry and hot seasons, respectively. Despite extensive biomass burning in the hot season, moderate levels of aerosols were due to the mixing with air masses from the Pacific Ocean. Diurnal distributions exhibit peaks during rush hour marked by minima in the OC/BC ratio and stagnant wind flow. The lowest concentrations in the afternoon hours could be due to deeper planetary boundary layer and reduced traffic. Overall, the concentrations of both BC and OC decrease with the increase in wind speed. The weekend effects, due to reduced emission during weekends, in the concentrations of both BC and OC were significant. Therefore, stricter abatement in vehicular emissions could substantially reduce pollution. A slope of BC/CO of 9.8 ngm< sup> -3< /sup> ppbv< sup> -1< /sup> for the wet season represents the emission ratio from vehicular sources. The highest of OC/BC (3 g g< sup> -1< /sup> ) in the hot season was due to the predominant influence of biomass burning and significant formation of secondary OC. The levels of BC and OC in Bangkok fall within the ranges of their concentrations measured in the major cities of East Asia. Copyright 2011 by the American Geophysical Union.
  • Michihiro Mochida, Chiharu Nishita-Hara, Hiroshi Furutani, Yuzo Miyazaki, Jinyoung Jung, Kimitaka Kawamura, Mitsuo Uematsu
    Journal of Geophysical Research Atmospheres 116 (6) 0148-0227 2011 [Refereed][Not invited]
     
    Hygroscopic growth of aerosol particles at 85% relative humidity and the number fraction of cloud condensation nuclei (CCN; 0.42%, 0.23%, and 0.10% supersaturation) as a function of dry diameter (24.1-359 nm) were measured simultaneously on board R/V Hakuho-Maru over the western North Pacific during August-September 2008. Highly hygroscopic and unimodal growth distributions were observed, except for aerosols, which showed lower hygroscopic growth over the northern Pacific. The measured particle hygroscopicity, CCN activation diameters, and chemical composition data suggest the dominance of internally mixed sulfate aerosols. Backward air mass trajectory analysis exhibits an intrusion of free tropospheric aerosol, which was likely influenced by Kasatochi's volcanic plume and which was linked to the low-hygroscopicity event. Frequent observation of the Hoppel minimum suggests that in-cloud processing over the Pacific enhanced and/or maintained the high hygroscopicity of accumulation mode particles. The CCN activation diameters predicted from median hygroscopic growth factors (gmedian) agreed well with those determined from the CCN efficiency spectra, without assuming surface tension reduction caused by organics or enhancement of bulk hygroscopicity at high RH caused by sparingly soluble or polymeric compounds. The CCN spectra predicted from gmedian and measured CCN activation diameters suggest that the high CCN activities of particles over the North Pacific are sustained by high hygroscopicity, while sporadic changes of aerosol origins produce the diversity of the aerosol properties. Copyright 2011 by the American Geophysical Union.
  • Yuzo Miyazaki, Kimitaka Kawamura, Maki Sawano
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 115 (D23210) doi:10.1029/2010JD014439  2169-897X 2010/12 [Refereed][Not invited]
     
    Size-segregated aerosol samples were collected over the western North Pacific in summer 2008 to investigate marine biological contribution to organic aerosols. The samples were analyzed for organic carbon (OC), water-soluble organic carbon (WSOC), and water-soluble organic compounds including diacids (C-2-C-9), omega-oxocarboxylic acids, and alpha-dicarbonyls as well as methanesulfonic acid (MSA). The average concentrations of OC and oxalic acid (C-2) were approximately two to three times larger in marine biologically more influenced aerosols, defined by the concentrations of MSA and azelaic acid (C-9), than in less influenced aerosols. WSOC, which showed a statistically significant correlation with MSA, accounted for 15-21% of total mass of the components determined in the submicrometer range of biologically more influenced aerosols. These values are comparable to those of water-insoluble organic carbon (WIOC) (similar to 14-23%), suggesting that organic aerosols in this region are enriched in secondary organic aerosols (SOA) linked to oceanic biological activity. In these aerosols, substantial fractions of C-2-C-4 diacids were found in the submicrometer size range. Positive correlations of oxalic acid with C-3-C-5 diacids and glyoxylic acid suggest that secondary production of oxalic acid occurs possibly in the aqueous aerosol phase via the oxidation of longer-chain diacids and glyoxylic acid in the oceanic region with higher biological productivity. We found similar concentration levels and size distributions of methylglyoxal between the two types of aerosols, suggesting that formation of oxalic acid via the oxidation of methylglyoxal from marine isoprene is insignificant in the study region.
  • Yutaka Kondo, Nobuyuki Takegawa, Hitoshi Matsui, Takuma Miyakawa, Makoto Koike, Yuzo Miyazaki, Yugo Kanaya, Michihiro Mochida, Mikinori Kuwata, Yu Morino, Manabu Shiraiwa
    JOURNAL OF THE METEOROLOGICAL SOCIETY OF JAPAN 88 (4) 597 - 624 0026-1165 2010/08 [Refereed][Not invited]
     
    Large amounts of reactive gases and aerosols are emitted from urban areas. Megacities, including the Tokyo Metropolitan Area (TMA), are very large, concentrated sources of these species affecting local, regional, and global ozone (O-3) and aerosol levels. Emissions strongly influence air quality and climate on these scales. In 2003-2004, we made intensive measurements of O-3 and chemical composition of aerosol particles with diameters less than I pm (PM1 aerosol) together with their precursors for the first time in Tokyo, Japan, as a part of the series of Integrated Measurement Program for Aerosol and Oxidant Chemistry in Tokyo (IMPACT) campaigns. Using these data, we investigated the formation and transport processes of O-3 and PM1 aerosols through the analysis of their temporal variations near the urban center of Tokyo and regions downwind. Key findings obtained in these studies are reviewed in this paper.
  • Yuzo Miyazaki, Kimitaka Kawamura, Maki Sawano
    GEOPHYSICAL RESEARCH LETTERS 37 (L06803) doi:10.1029/2010GL042483  0094-8276 2010/03 [Refereed][Not invited]
     
    Size-segregated aerosol samples were collected over the western North Pacific in summer 2008 for the measurements of organic nitrogen (ON) and organic carbon (OC). ON and OC showed bimodal size distributions. Their concentrations showed positive correlation with those of biogenic tracers, methanesulfonic acid (MSA) and azelaic acid (C-9). We found that average ON and OC concentrations were twice greater in aerosols collected in the oceanic region with higher biological productivity than in the regions with lower productivity. The average ON/OC ratios are higher (0.49 +/- 0.11) in more biologically influenced aerosols than those (0.35 +/- 0.10) in less influenced aerosols. Stable carbon isotopic analysis indicates that marine-derived carbon accounted for similar to 46-72% of total carbon in more biologically influenced aerosols. These results provide evidence that organic aerosols in this region are enriched in ON that is linked to oceanic biological activity and the subsequent emissions to the atmosphere. Citation: Miyazaki, Y., K. Kawamura, and M. Sawano (2010), Size distributions of organic nitrogen and carbon in remote marine aerosols: Evidence of marine biological origin based on their isotopic ratios, Geophys. Res. Lett., 37, L06803, doi: 10.1029/2010GL042483.
  • Yuzo Miyazaki, Kimitaka Kawamura, Maki Sawano
    Journal of Geophysical Research Atmospheres 115 (23) 0148-0227 2010 [Refereed][Not invited]
     
    Size-segregated aerosol samples were collected over the western North Pacific in summer 2008 to investigate marine biological contribution to organic aerosols. The samples were analyzed for organic carbon (OC), water-soluble organic carbon (WSOC), and water-soluble organic compounds including diacids (C< inf> 2< /inf> -C< inf> 9< /inf> ), ω-oxocarboxylic acids, and α-dicarbonyls as well as methanesulfonic acid (MSA). The average concentrations of OC and oxalic acid (C< inf> 2< /inf> ) were approximately two to three times larger in marine biologically more influenced aerosols, defined by the concentrations of MSA and azelaic acid (C< inf> 9< /inf> ), than in less influenced aerosols. WSOC, which showed a statistically significant correlation with MSA, accounted for 15-21% of total mass of the components determined in the submicrometer range of biologically more influenced aerosols. These values are comparable to those of water-insoluble organic carbon (WIOC) (∼14-23%), suggesting that organic aerosols in this region are enriched in secondary organic aerosols (SOA) linked to oceanic biological activity. In these aerosols, substantial fractions of C< inf> 2< /inf> -C< inf> 4< /inf> diacids were found in the submicrometer size range. Positive correlations of oxalic acid with C < inf> 3< /inf> -C< inf> 5< /inf> diacids and glyoxylic acid suggest that secondary production of oxalic acid occurs possibly in the aqueous aerosol phase via the oxidation of longer-chain diacids and glyoxylic acid in the oceanic region with higher biological productivity. We found similar concentration levels and size distributions of methylglyoxal between the two types of aerosols, suggesting that formation of oxalic acid via the oxidation of methylglyoxal from marine isoprene is insignificant in the study region. Copyright 2010 by the American Geophysical Union.
  • S. Han, Y. Kondo, N. Oshima, N. Takegawa, Y. Miyazaki, M. Hu, P. Lin, Z. Deng, Y. Zhao, N. Sugimoto, Y. Wu
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 114 (D23202) doi:10.1029/2009JD012027  2169-897X 2009/12 [Refereed][Not invited]
     
    Concentrations of elemental carbon (EC), carbon monoxide (CO), and carbon dioxide (CO2) were measured in Beijing between 2005 and 2006. EC was measured every hour with a semicontinuous thermal optical analyzer. The observed concentrations were rather uniform over a distance of about 50 km from the observation site. The annual average concentrations of EC and CO were 6.9 mu gC m(-3) and 1120 parts per billion by volume, respectively. The concentrations of these species increased with decreasing near-surface wind speed (WS). The slopes of the CO-CO2, EC-CO2, and EC-CO correlations are used to estimate major EC and CO sources. In the weak wind regime (WS <= 2.0 m s(-1)), the median EC, Delta EC/Delta CO2, and Delta EC/Delta CO (except for winter) increased in the late evening and remained high until early morning. The traffic of heavy duty diesel trucks during nighttime was about 20 times higher than that during daytime. These results indicate a dominant contribution of exhaust from diesel vehicles to the nighttime EC. In winter, the nighttime CO and Delta CO/Delta CO2 ratio were largely higher than those in the other seasons. The most likely cause is the increase in the CO emissions from the exhaust of gasoline vehicles at low temperature. The Delta EC/Delta CO2 ratio in winter was lower than that in fall, indicating no significant additional EC emissions. The diurnal variations of EC, CO, CO2, and Delta EC/Delta CO were similar between weekdays and weekends. The slopes of the CO-CO2-EC correlations are compared with the CO-CO2-EC ratios derived from a published emission inventory in the Beijing area.
  • Yuzo Miyazaki, Shankar G. Aggarwal, Khem Singh, Prabhat K. Gupta, Kimitaka Kawamura
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 114 (D19206) doi:10.1029/2009JD011790  2169-897X 2009/10 [Refereed][Not invited]
     
    Day-and nighttime aerosol samples were collected at an urban site in New Delhi, India, in winter 2006-2007. They were studied for low molecular weight dicarboxylic acids and related compounds, as well as total water-soluble organic carbon (TWSOC). High concentrations of diacids (up to 6.03 mu g m(-3)), TWSOC, and OC were obtained, which are substantially higher than those previously observed at other urban sites in Asia. Daytime TWSOC/OC ratio (37%) was on average higher than that in nighttime (25%). In particular, more water-soluble OC (M-WSOC) to TWSOC ratio in daytime (50%) was twice higher than in nighttime (27%), suggesting that aerosols in New Delhi are photochemically more processed in daytime to result in more water-soluble organic compounds. Oxalic acid (C-2) was found as the most abundant dicarboxylic acid, followed by succinic (C-4) and malonic (C-3) acids. Contributions of C-2 to M-WSOC were greater (av. 8%) in nighttime than daytime (av. 3%). Positive correlations of C-2 with malic acid (hC(4)), glyoxylic acid (omega C-2), and relative humidity suggest that secondary production of C-2 probably in aqueous phase is important in nighttime via the oxidation of both longer-chain diacids and omega C-2. C-2 also showed a positive correlation with potassium (K+) in nighttime, suggesting that the enhanced C-2 concentrations are associated with biomass/biofuel burning. More tight, positive correlation between lesswater-soluble OC (L-WSOC) and K+ was found in both day- and nighttime, suggesting that L-WSOC, characterized by longer chain and/or higher molecular weight compounds, is significantly influenced by primary emissions from biomass/biofuel burning.
  • H. Matsui, M. Koike, Y. Kondo, N. Takegawa, K. Kita, Y. Miyazaki, M. Hu, S. Y. Chang, D. R. Blake, J. D. Fast, R. A. Zaveri, D. G. Streets, Q. Zhang, T. Zhu
    Journal of Geophysical Research Atmospheres 114 (15) 0148-0227 2009/08/16 [Refereed][Not invited]
     
    Regional aerosol model calculations were made using the Weather Research and Forecasting (WRF)-Community Multiscale Air Quality (CMAQ) and WRF-chem models to study spatial and temporal variations of aerosols around Beijing, China, in the summer of 2006, when the Campaigns of Air Quality Research in Beijing and Surrounding Region 2006 (CAREBeijing) intensive campaign was conducted. Model calculations captured temporal variations of primary (such as elemental carbon. (EC)) and secondary (such as sulfate) aerosols observed in and around Beijing. The spatial distributions of aerosol optical depth observed by the MODTS satellite sensors were also reproduced over northeast China. Model calculations showed distinct differences in spatial distributions between primary and secondary aerosols in association with synoptic-scale meteorology. Secondary aerosols increased in air around Beijing on a scale of about 1000 × 1000 km< sup> 2< /sup> under an anticyclonic pressure system. This air mass was transported northward from the high anthropogenic emission area extending south of Beijing with continuous photochemical production. Subsequent cold front passage brought clean air from the north, and polluted air around Beijing was swept to the south of Beijing. This cycle was repeated about once a week and was found to be responsible for observed enhancements/reductions of aerosols at the intensive measurement sites. In contrast to secondary aerosols, the spatial distributions of primary aerosols (EC) reflected those of emissions, resulting in only slight variability despite the changes in synopticscale meteorology. In accordance with these results, source apportionment simulations revealed that primary aerosols around Beijing were controlled by emissions within 100 km around Beijing within the preceding 24 h, while emissions as far as 500 km and within the preceding 3 days were found to affect secondary aerosols. Copyright 2009 by the American Geophysical Union.
  • H. Matsui, M. Koike, Y. Kondo, N. Takegawa, K. Kita, Y. Miyazaki, M. Hu, S. -Y. Chang, D. R. Blake, J. D. Fast, R. A. Zaveri, D. G. Streets, Q. Zhang, T. Zhu
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 114 2169-897X 2009/08 [Refereed][Not invited]
     
    Regional aerosol model calculations were made using the Weather Research and Forecasting (WRF)-Community Multiscale Air Quality (CMAQ) and WRF-chem models to study spatial and temporal variations of aerosols around Beijing, China, in the summer of 2006, when the Campaigns of Air Quality Research in Beijing and Surrounding Region 2006 (CAREBeijing) intensive campaign was conducted. Model calculations captured temporal variations of primary ( such as elemental carbon (EC)) and secondary ( such as sulfate) aerosols observed in and around Beijing. The spatial distributions of aerosol optical depth observed by the MODIS satellite sensors were also reproduced over northeast China. Model calculations showed distinct differences in spatial distributions between primary and secondary aerosols in association with synoptic-scale meteorology. Secondary aerosols increased in air around Beijing on a scale of about 1000 x 1000 km(2) under an anticyclonic pressure system. This air mass was transported northward from the high anthropogenic emission area extending south of Beijing with continuous photochemical production. Subsequent cold front passage brought clean air from the north, and polluted air around Beijing was swept to the south of Beijing. This cycle was repeated about once a week and was found to be responsible for observed enhancements/reductions of aerosols at the intensive measurement sites. In contrast to secondary aerosols, the spatial distributions of primary aerosols (EC) reflected those of emissions, resulting in only slight variability despite the changes in synoptic-scale meteorology. In accordance with these results, source apportionment simulations revealed that primary aerosols around Beijing were controlled by emissions within 100 km around Beijing within the preceding 24 h, while emissions as far as 500 km and within the preceding 3 days were found to affect secondary aerosols.
  • R. Xiao, N. Takegawa, Y. Kondo, Y. Miyazaki, T. Miyakawa, M. Hu, M. Shao, L. M. Zeng, A. Hofzumahaus, F. Holland, K. Lu, N. Sugimoto, Y. Zhao, Y. H. Zhang
    ATMOSPHERIC ENVIRONMENT 43 (24) 3754 - 3763 1352-2310 2009/08 [Refereed][Not invited]
     
    Size-resolved chemical compositions of non-refractory submicron aerosols were measured using a quadrupole Aerodyne aerosol mass spectrometer at a rural site near Guangzhou in the Pearl River Delta (PRD) of China in the summer of 2006. Two cases characterized as the outflows from the PRD urban region with plumes of high SO2 concentration were investigated. The evolution of sulfate size distributions was observed on a timescale of several hours. Namely mass concentrations of sulfate in the condensation mode (with vacuum aerodynamic diameters (D-va) < 300 nm) increased at a rate of about 0.17-0.37 ppbv h(-1) during the daytime. This finding was consistent with the sulfuric acid production rates of about 0.17-0.3 ppbv h(-1), as calculated from the observed gas-phase concentrations of OH (similar to 3.3 x 10(6)-1.7 x 10(7) cm(-3)) and SO2 (similar to 3-21.2 ppbv). This implies that the growth of sulfate in the condensation mode was mainly due to gas-phase oxidation of SO2. The observed rapid increase was caused mainly by the concurrent high concentrations of OH and SO2 in the air mass. The evolution of the mass size distributions of m/z 44, a tracer for oxygenated organic aerosol (OOA), was very similar to that of sulfate. The mass loadings of m/z 44 were strongly correlated with those of sulfate (r(2) = 0.99) in the condensation mode, indicating that ODA might also be formed by the gas-phase oxidation of volatile organic compound (VOC) precursors. It is likely that sulfate and ODA were internally mixed throughout the whole size range in the air mass. (C) 2009 Elsevier Ltd. All rights reserved.
  • Y. Miyazaki, Y. Kondo, M. Shiraiwa, N. Takegawa, T. Miyakawa, S. Han, K. Kita, M. Hu, Z. Q. Deng, Y. Zhao, N. Sugimoto, D. R. Blake, R. J. Weber
    Journal of Geophysical Research Atmospheres 114 (14) 0148-0227 2009/07/27 [Refereed][Not invited]
     
    Online measurements of water-soluble organic carbon (WSOC) aerosols were made using a particle-into-liquid sampler (PILS) combined with a total organic carbon (TOC) analyzer at a rural site in the Pearl River Delta region, China, in July 2006. A macroporous nonionic (DAX-8) resin was used to quantify hydrophilic and hydrophobic WSOC, which are defined as the fractions of WSOC that penetrated through and retained on the DAX-8 column, respectively. Laboratory calibrations showed that hydrophilic WSOC (WSOCHPI) included low-molecular aliphatic dicarboxylic acids and carbonyls, saccharides, and amines, while hydrophobic WSOC (WSOCHPO) included longer-chain aliphatic dicarboxylic acids and carbonyls, aromatic acids, phenols, organic nitrates, cyclic acids, and fulvic acids. On average, total WSOC (TWSOC) accounted for 60% of OC, and WSOC< inf> HPO< /inf> accounted for 60% of TWSOC. Both WSOC < inf> HIP< /inf> and WSOC< inf> HPO< /inf> increased with photochemical aging determined from the NO< inf> x< /inf> /NO< inf> y< /inf> ratio. In particular, the average WSOC< inf> HPO< /inf> mass was found to increase by a factor of five within a timescale of ∼10 hours, which was substantially larger than that of WSOC< inf> HPI< /inf> (by a factor of 2-3). The total increase in OC mass with photochemical aging was associated with the large increase in WSOC< inf> HPO< /inf> mass. These results, combined with the laboratory calibrations, suggest that significant amounts of hydrophobic organic compounds (likely containing large carbon numbers) were produced by photochemical processing. By contrast, water-insoluble OC (WIOC) mass did not exhibit significant changes with photochemical aging, suggesting that chemical transformation of WIOC to WSOC was not a dominant process for the production of WSOC during the study period. Copyright 2009 by the American Geophysical Union.
  • Y. Miyazaki, Y. Kondo, M. Shiraiwa, N. Takegawa, T. Miyakawa, S. Han, K. Kita, M. Hu, Z. Q. Deng, Y. Zhao, N. Sugimoto, D. R. Blake, R. J. Weber
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 114 (D14208) doi:10.1029/2009JD011736  2169-897X 2009/07 [Refereed][Not invited]
     
    Online measurements of water-soluble organic carbon (WSOC) aerosols were made using a particle-into-liquid sampler (PILS) combined with a total organic carbon (TOC) analyzer at a rural site in the Pearl River Delta region, China, in July 2006. A macroporous nonionic (DAX-8) resin was used to quantify hydrophilic and hydrophobic WSOC, which are defined as the fractions of WSOC that penetrated through and retained on the DAX-8 column, respectively. Laboratory calibrations showed that hydrophilic WSOC (WSOCHPI) included low-molecular aliphatic dicarboxylic acids and carbonyls, saccharides, and amines, while hydrophobic WSOC (WSOCHPO) included longer-chain aliphatic dicarboxylic acids and carbonyls, aromatic acids, phenols, organic nitrates, cyclic acids, and fulvic acids. On average, total WSOC (TWSOC) accounted for 60% of OC, and WSOCHPO accounted for 60% of TWSOC. Both WSOCHPI and WSOCHPO increased with photochemical aging determined from the NOx/NOy ratio. In particular, the average WSOCHPO mass was found to increase by a factor of five within a timescale of similar to 10 hours, which was substantially larger than that of WSOCHPI (by a factor of 2-3). The total increase in OC mass with photochemical aging was associated with the large increase in WSOCHPO mass. These results, combined with the laboratory calibrations, suggest that significant amounts of hydrophobic organic compounds (likely containing large carbon numbers) were produced by photochemical processing. By contrast, water-insoluble OC (WIOC) mass did not exhibit significant changes with photochemical aging, suggesting that chemical transformation of WIOC to WSOC was not a dominant process for the production of WSOC during the study period.
  • Peng Lin, Min Hu, Z. Deng, J. Slanina, S. Han, Y. Kondo, N. Takegawa, Y. Miyazaki, Y. Zhao, N. Sugimoto
    Journal of Geophysical Research Atmospheres 114 (11) 0148-0227 2009/06/16 [Refereed][Not invited]
     
    Organic carbon (OC) and elemental carbon (EC) in PM< inf> 2.5< /inf> were measured hourly with a semicontinuous thermal-optical analyzer in Beijing, China, during four seasons from November 2005 to October 2006. The average OC concentrations measured at Peking University (PKU) site in urban Beijing were 20 ± 19, 12 ± 7, 10 ± 5, and 18 ± 11 μgC/m < sup> 3< /sup> in winter, spring, summer, and autumn, respectively. Distinct seasonal, and diurnal patterns of OC were observed, and their concentrations were significantly influenced by the seasonal and diurnal changes in sources, emission rates, and mesoscale meteorology. The impacts of meteorological parameters such as wind and precipitation on OC and EC concentrations are also discussed. OC and EC concentrations were found to be well correlated in winter, spring, and autumn, indicating their common origins, while their correlation was poorer in summer, especially in the afternoon, indicating that the influence of secondary organic carbon (SOC) was significant for this period. SOC concentrations were estimated by using the EC-tracer method as about 2.6 ± 3.1, 2.8 ± 2.4, 4.5 ± 2.9, and 4.1 ± 4.0 μgC/m< sup> 3< /sup> , accounting for 1.9%, 27%, 45%, and 23% of total, organic carbon in winter, spring, summer, and autumn, respectively. This result showed that the relative contribution of SOC to OC in PM< inf> 2.5< /inf> at this urban location was only comparable to that of primary organic carbon (POC) to OC in summer, while in the other three seasons, OC was dominated by POC. Copyright 2009 by the American Geophysical Union.
  • Peng Lin, Min Hu, Z. Deng, J. Slanina, S. Han, Y. Kondo, N. Takegawa, Y. Miyazaki, Y. Zhao, N. Sugimoto
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 114 D00G11  2169-897X 2009/06 [Refereed][Not invited]
     
    Organic carbon (OC) and elemental carbon (EC) in PM2.5 were measured hourly with a semicontinuous thermal-optical analyzer in Beijing, China, during four seasons from November 2005 to October 2006. The average OC concentrations measured at Peking University (PKU) site in urban Beijing were 20 +/- 19, 12 +/- 7, 10 +/- 5, and 18 +/- 11 mu gC/m(3) in winter, spring, summer, and autumn, respectively. Distinct seasonal and diurnal patterns of OC were observed, and their concentrations were significantly influenced by the seasonal and diurnal changes in sources, emission rates, and mesoscale meteorology. The impacts of meteorological parameters such as wind and precipitation on OC and EC concentrations are also discussed. OC and EC concentrations were found to be well correlated in winter, spring, and autumn, indicating their common origins, while their correlation was poorer in summer, especially in the afternoon, indicating that the influence of secondary organic carbon (SOC) was significant for this period. SOC concentrations were estimated by using the EC-tracer method as about 2.6 +/- 3.1, 2.8 +/- 2.4, 4.5 +/- 2.9, and 4.1 +/- 4.0 mu gC/m(3), accounting for 19%, 27%, 45%, and 23% of total organic carbon in winter, spring, summer, and autumn, respectively. This result showed that the relative contribution of SOC to OC in PM2.5 at this urban location was only comparable to that of primary organic carbon (POC) to OC in summer, while in the other three seasons, OC was dominated by POC.
  • P. Achtert, W. Birmili, A. Nowak, B. Wehner, A. Wiedensohler, N. Takegawa, Y. Kondo, Y. Miyazaki, M. Hu, T. Zhu
    Journal of Geophysical Research Atmospheres 114 (8) 0148-0227 2009/04/27 [Refereed][Not invited]
     
    The hygroscopic growth of atmospheric submicrometer particle size distributions (diameter D< inf> p< /inf> ranging from 22 to 900 nm) was studied at a rural/suburban site in the North China Plain within the framework of the international Campaigns of Air Quality Research, in Beijing and Surrounding Region 2006 (CAREBeijing-2006) research, project. The goal, was to characterize the regional aerosol, in the polluted northeastern plain in China. Size descriptive hygroscopic growth factors (DHGFs) were determined as a function of relative humidity (RH) by relating the particle number size distribution at a dry condition (< 30%) to those measured at higher RHs (RH = 56, 76, 85, and 91%) for the diameter range from 30 to 300 nm. In the size range of the accumulation mode (D< inf> p< /inf> > 100 nm), the DHGF are substantially higher than in the Aitken particle mode (D< inf> p< /inf> < 100 nm) as a result of different chemical composition. The size-dependent behavior of the DHGF highlights the relevance of particulate sulfate production over the North China Plain, accomplished by secondary formation from the gas phase and, potentially, liquid phase processes in convective clouds. Furthermore, all results concerning the DHGF show a significant dependency on meteorological air masses. The hygroscopic growth of accumulation mode particles correlates significantly with the PM< inf> 1< /inf> -mass fraction, of sulfate ions determined by chemical analysis. Finally, this investigation provides a parameterization of the hygroscopic growth of 250-nm particles, which might be useful when predicting visibility and radiative forcing and performing atmospheric aerosol model validations. Copyright 2009 by the American Geophysical Union.
  • N. Takegawa, T. Miyakawa, M. Kuwata, Y. Kondo, Y. Zhao, S. Han, K. Kita, Y. Miyazaki, Z. Deng, R. Xiao, M. Hu, D. Van Pinxteren, H. Herrmann, A. Hofzumahaus, F. Holland, A. Wahner, D. R. Blake, N. Sugimoto, T. Zhu
    Journal of Geophysical Research Atmospheres 114 (7) 0148-0227 2009/04/16 [Refereed][Not invited]
     
    Ground-based measurements of aerosol and trace gases were conducted at a rural site in Beijing in the summer of 2006 as a part of the Campaigns of Air Quality Research in Beijing and Surrounding Region 2006 (CAREBeijing 2006). The size-resolved chemical composition of submicron aerosol was measured using an Aerodyne quadrupole aerosol mass spectrometer (AMS). The data obtained from 15 August to 10 September 2006 are presented. Meteorological analysis shows that the measurement period can be characterized as a cycle of low wind speed periods over the course of a few days (stagnant periods) followed by rapid advection of clean air from the north/northwest mostly due to passage of a midlatitude cyclone. Mass concentrations of total measured aerosol with diameters less than 1 μm. (total. PM1), which is defined as the sum of elemental carbon and nonrefractory components measured by the AMS, were highly variable, ranging from. ∼2 to ∼100 μm-3, Large variability of the PM1 composition and drastic changes in the sulfate (SO 2-4) size distribution were observed to be associated with the cycle of stagnant periods and advection of clean air, indicating that both chemical and physical properties of aerosols were significantly altered on a time scale of a few days. We have found the dominance of organic aerosol at lower total PM1 mass loadings and that of SO2-4 at higher mass loadings, which may have important implications for the PM control strategy in Beijing. Possible factors affecting the evolution of the mass concentration and size distribution of SO2-4 are discussed. Copyright 2009 by the American Geophysical Union.
  • P. Achtert, W. Birmili, A. Nowak, B. Wehner, A. Wiedensohler, N. Takegawa, Y. Kondo, Y. Miyazaki, M. Hu, T. Zhu
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 114 (D00G07) doi:10.1029/2008JD010921  2169-897X 2009/04 [Refereed][Not invited]
     
    The hygroscopic growth of atmospheric submicrometer particle size distributions (diameter D-p ranging from 22 to 900 nm) was studied at a rural/suburban site in the North China Plain within the framework of the international Campaigns of Air Quality Research in Beijing and Surrounding Region 2006 (CAREBeijing-2006) research project. The goal was to characterize the regional aerosol in the polluted northeastern plain in China. Size descriptive hygroscopic growth factors (DHGFs) were determined as a function of relative humidity (RH) by relating the particle number size distribution at a dry condition (<30%) to those measured at higher RHs (RH = 56, 76, 85, and 91%) for the diameter range from 30 to 300 nm. In the size range of the accumulation mode (D-p > 100 nm), the DHGF are substantially higher than in the Aitken particle mode (D-p < 100 nm) as a result of different chemical composition. The size-dependent behavior of the DHGF highlights the relevance of particulate sulfate production over the North China Plain, accomplished by secondary formation from the gas phase and, potentially, liquid phase processes in convective clouds. Furthermore, all results concerning the DHGF show a significant dependency on meteorological air masses. The hygroscopic growth of accumulation mode particles correlates significantly with the PM1-mass fraction of sulfate ions determined by chemical analysis. Finally, this investigation provides a parameterization of the hygroscopic growth of 250-nm particles, which might be useful when predicting visibility and radiative forcing and performing atmospheric aerosol model validations.
  • N. Takegawa, T. Miyakawa, M. Kuwata, Y. Kondo, Y. Zhao, S. Han, K. Kita, Y. Miyazaki, Z. Deng, R. Xiao, M. Hu, D. van Pinxteren, H. Herrmann, A. Hofzumahaus, F. Holland, A. Wahner, D. R. Blake, N. Sugimoto, T. Zhu
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 114 2169-897X 2009/04 [Refereed][Not invited]
     
    Ground-based measurements of aerosol and trace gases were conducted at a rural site in Beijing in the summer of 2006 as a part of the Campaigns of Air Quality Research in Beijing and Surrounding Region 2006 (CAREBeijing 2006). The size-resolved chemical composition of submicron aerosol was measured using an Aerodyne quadrupole aerosol mass spectrometer (AMS). The data obtained from 15 August to 10 September 2006 are presented. Meteorological analysis shows that the measurement period can be characterized as a cycle of low wind speed periods over the course of a few days (stagnant periods) followed by rapid advection of clean air from the north./northwest mostly due to passage of a midlatitude cyclone. Mass concentrations of total measured aerosol with diameters less than 1 mu m (total PM1), which is defined as the sum of elemental carbon and nonrefractory components measured by the AMS, were highly variable, ranging from similar to 2 to similar to 100 mu g m(-3). Large variability of the PM1 composition and drastic changes in the sulfate (SO42-) size distribution were observed to be associated with the cycle of stagnant periods and advection of clean air, indicating that both chemical and physical properties of aerosols were significantly altered on a time scale of a few days. We have found the dominance of organic aerosol at lower total PM1 mass loadings and that of SO42- at higher mass loadings, which may have important implications for the PM control strategy in Beijing. Possible factors affecting the evolution of the mass concentration and size distribution of SO42- are discussed.
  • N. Oshima, M. Koike, Y. Zhang, Y. Kondo, N. Moteki, N. Takegawa, Y. Miyazaki
    Journal of Geophysical Research Atmospheres 114 (6) D06210  0148-0227 2009/03/27 [Refereed][Not invited]
     
    The mixing state of black carbon (BC) aerosols, namely, the degree to which. BC particles are coated with other aerosol components, has been recognized as important for evaluating aerosol radiative forcing. In order to resolve the BC mixing state explicitly in model simulations, a two-dimensional aerosol representation, in which aerosols are given for individual particle diameters and BC mass fractions, is introduced. This representation was incorporated into an aerosol module, the Model of Aerosol Dynamics, Reaction, Ionization, and Dissolution (MADRID), and a new box model, MADRID-BC, was developed. MADRID-BC can accurately simulate changes in the entire BC mixing state resulting from condensation/evaporation processes. Aircraft observations conducted in. March 2004 show that the mass fraction of thickly coated BC particles increased in air horizontally transported out from an urban area in Japan over the ocean. MADRID-BC generally reproduces this feature well when observed bulk aerosol concentrations are used as constraints. The model simulations in this particular case show that for particles with BC core diameters of 100-200 nm, the particle diameters, including both core and coating materials, had already increased by a factor of 1.6 on average when they left the source region and by as large as a factor of 1.9 of the BC core diameters after their transport over the ocean for a half day. The model simulations also show that 58% of the total condensed mass was partitioned onto BC-free particles during transport, indicating their importance for the BC mixing state. Although the model simulations are applied to a limited number of the observations in this study, they clearly show the time evolution of the coating thicknesses of BC-containing particles, which is necessary for calculating aerosol optical properties and cloud condensation nuclei activities. Copyright 2009 by the American Geophysical Union.
  • N. Oshima, M. Koike, Y. Zhang, Y. Kondo, N. Moteki, N. Takegawa, Y. Miyazaki
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 114 2169-897X 2009/03 [Refereed][Not invited]
     
    The mixing state of black carbon (BC) aerosols, namely, the degree to which BC particles are coated with other aerosol components, has been recognized as important for evaluating aerosol radiative forcing. In order to resolve the BC mixing state explicitly in model simulations, a two-dimensional aerosol representation, in which aerosols are given for individual particle diameters and BC mass fractions, is introduced. This representation was incorporated into an aerosol module, the Model of Aerosol Dynamics, Reaction, Ionization, and Dissolution (MADRID), and a new box model, MADRID-BC, was developed. MADRID-BC can accurately simulate changes in the entire BC mixing state resulting from condensation/evaporation processes. Aircraft observations conducted in March 2004 show that the mass fraction of thickly coated BC particles increased in air horizontally transported out from an urban area in Japan over the ocean. MADRID-BC generally reproduces this feature well when observed bulk aerosol concentrations are used as constraints. The model simulations in this particular case show that for particles with BC core diameters of 100-200 nm, the particle diameters, including both core and coating materials, had already increased by a factor of 1.6 on average when they left the source region and by as large as a factor of 1.9 of the BC core diameters after their transport over the ocean for a half day. The model simulations also show that 58% of the total condensed mass was partitioned onto BC-free particles during transport, indicating their importance for the BC mixing state. Although the model simulations are applied to a limited number of the observations in this study, they clearly show the time evolution of the coating thicknesses of BC-containing particles, which is necessary for calculating aerosol optical properties and cloud condensation nuclei activities.
  • H. Matsui, M. Koike, N. Takegawa, Y. Kondo, R. J. Griffin, Y. Miyazaki, Y. Yokouchi, T. Ohara
    Journal of Geophysical Research Atmospheres 114 (4) 0148-0227 2009/02/27 [Refereed][Not invited]
     
    Quantitative evaluation of the performance of one of the most advanced mechanistic secondary organic aerosol (SOA) modules/models, the Model of Aerosol Dynamics, Reaction, Ionization, and Dissolution 2 (MADRID2) in the three-dimensional Models-3/ Community Multiscale Air Quality (CMAQ), in urban air is made. Model calculations are compared for the Tokyo, Japan, metropolitan area with measurements made using an Aerodyne quadrupole aerosol mass spectrometer (Q-AMS) at an urban site for 9 days in July and August 2003. In general, model calculations reproduced absolute values and temporal variations of meteorological parameters, C< inf> 2< /inf> C< inf> 8< /inf> volatile organic compounds (VOCs), NO (NO + NO< inf> 2< /inf> ), inorganic aerosols, and 03 concentrations reasonably well at this site. However, model-calculated SOA concentrations are a factor of 5 smaller than observed oxygenated organic aerosol (OOA) concentrations, and calculated total organic aerosol (OA = SOA + primary organic aerosol) concentrations are smaller by a factor of 2, indicating missing processes or sources in the current organic aerosol model calculations. On the other hand, observed features of diurnal and day-to-day variations of OOA were captured by our model calculations. Because of the large quantity of unidentified total nonmethane VOCs (NMVOCs) in urban air, a possible contribution of SOA formation from high-molecular-weight VOCs is examined through simple sensitivity studies, in which emissions are increased to account for unidentified NMVOCs. It is found that they are potentially one of the missing SOA sources, demonstrating the importance of reliable measurements of high-molecular-weight VOCs and total NMVOCs. Relationships between SOA and 03, including regional ( 150 x 150 km2) enhancements around the Tokyo metropolitan area, are also discussed. © 2009 by the American Geophysical Union.
  • L. K. Sahu, Y. Kondo, Y. Miyazaki, M. Kuwata, M. Koike, N. Takegawa, H. Tanimoto, H. Matsueda, S. C. Yoon, Y. J. Kim
    Journal of Geophysical Research Atmospheres 114 (3) 0148-0227 2009/02/16 [Refereed][Not invited]
     
    Anthropogenic aerosols were measured together with CO at Gosan (33°17′N, 126°10′E) on Jeju Island, South Korea, between 17 March and 5 April 2005. Outflow of these aerosols from the Asian continent was associated with a high-pressure system centered over the northern region of China and Mongolia. Air masses are classified into five distinct categories on the basis of origin: marine, free troposphere, Yellow Sea, Korea, and China. The concentrations of aerosols and CO show large variations because of the alternation of air masses, while wet scavenging of aerosols was another important factor during precipitation events at Gosan. The average mass concentrations of black carbon (BC), organic carbon (OC), water-soluble organic carbon (WSOC), and sulfate (SO< inf> 4< /inf> < sup> 2-< /sup> ) aerosols were 1.2 ± 0.8 μgC m< sup> -3< /sup> , 4.2 ± 1.6 μgC m< sup> -3< /sup> , 1.3 ± 1.0 μgC m< sup> -3< /sup> , and 4.0 ± 3.4 μg m< sup> -3< /sup> , respectively. Almost all species concentrations were highest in Chinese air masses, while they were lowest in marine air masses. The observed ΔBC/ΔCO slope of 9.7 ng m< sup> -3< /sup> ppbv< sup> -1< /sup> in Chinese outflow agrees reasonably with the estimates of the BC/CO emission ratios over northeastern China. The transport efficiencies of SO< inf> x< /inf> (SO< inf> 2< /inf> + SO< inf> 4< /inf> < sup> 2-< /sup> ) are calculated to be 40-45% from the observed SO< inf> x< /inf> -CO correlation. The relationships of the SO< inf> 4< /inf> < sup> 2-< /sup> /BC and WSOC/BC ratios with transport time from the continent suggest that a majority of SO< inf> 4< /inf> < sup> 2-< /sup> and WSOC aerosols were formed by about 1.5 days after the air masses left the East Asian continent. Copyright 2009 by the American Geophysical Union.
  • L. K. Sahu, Y. Kondo, Y. Miyazaki, M. Kuwata, M. Koike, N. Takegawa, H. Tanimoto, H. Matsueda, S. C. Yoon, Y. J. Kim
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 114 (D03301) doi:10.1029/2008JD010306  2169-897X 2009/02 [Refereed][Not invited]
     
    Anthropogenic aerosols were measured together with CO at Gosan (33 degrees 17'N, 126 degrees 10'E) on Jeju Island, South Korea, between 17 March and 5 April 2005. Outflow of these aerosols from the Asian continent was associated with a high-pressure system centered over the northern region of China and Mongolia. Air masses are classified into five distinct categories on the basis of origin: marine, free troposphere, Yellow Sea, Korea, and China. The concentrations of aerosols and CO show large variations because of the alternation of air masses, while wet scavenging of aerosols was another important factor during precipitation events at Gosan. The average mass concentrations of black carbon (BC), organic carbon (OC), water-soluble organic carbon (WSOC), and sulfate (SO42-) aerosols were 1.2 +/- 0.8 mu gC m(-3), 4.2 +/- 1.6 mu gC m(-3), 1.3 +/- 1.0 mu gC m(-3), and 4.0 +/- 3.4 mu g m(-3), respectively. Almost all species concentrations were highest in Chinese air masses, while they were lowest in marine air masses. The observed Delta BC/Delta CO slope of 9.7 ng m(-3) ppbv(-1) in Chinese outflow agrees reasonably with the estimates of the BC/CO emission ratios over northeastern China. The transport efficiencies of SOx (SO2 + SO42-) are calculated to be 40-45% from the observed SOx-CO correlation. The relationships of the SO42-/BC and WSOC/BC ratios with transport time from the continent suggest that a majority of SO42- and WSOC aerosols were formed by about 1.5 days after the air masses left the East Asian continent.
  • H. Matsui, M. Koike, N. Takegawa, Y. Kondo, R. J. Griffin, Y. Miyazaki, Y. Yokouchi, T. Ohara
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 114 (D04201) 2169-897X 2009/02 [Refereed][Not invited]
     
    Quantitative evaluation of the performance of one of the most advanced mechanistic secondary organic aerosol (SOA) modules/models, the Model of Aerosol Dynamics, Reaction, Ionization, and Dissolution 2 (MADRID2) in the three-dimensional Models-3/Community Multiscale Air Quality (CMAQ), in urban air is made. Model calculations are compared for the Tokyo, Japan, metropolitan area with measurements made using an Aerodyne quadrupole aerosol mass spectrometer (Q-AMS) at an urban site for 9 days in July and August 2003. In general, model calculations reproduced absolute values and temporal variations of meteorological parameters, C-2-C-8 volatile organic compounds (VOCs), NOx (NO + NO2), inorganic aerosols, and O-3 concentrations reasonably well at this site. However, model-calculated SOA concentrations are a factor of 5 smaller than observed oxygenated organic aerosol (OOA) concentrations, and calculated total organic aerosol (OA = SOA + primary organic aerosol) concentrations are smaller by a factor of 2, indicating missing processes or sources in the current organic aerosol model calculations. On the other hand, observed features of diurnal and day-to-day variations of OOA were captured by our model calculations. Because of the large quantity of unidentified total nonmethane VOCs (NMVOCs) in urban air, a possible contribution of SOA formation from high-molecular-weight VOCs is examined through simple sensitivity studies, in which emissions are increased to account for unidentified NMVOCs. It is found that they are potentially one of the missing SOA sources, demonstrating the importance of reliable measurements of high-molecular-weight VOCs and total NMVOCs. Relationships between SOA and O3, including regional (similar to 150 x 150 km(2)) enhancements around the Tokyo metropolitan area, are also discussed.
  • S. Han, Y. Kondo, N. Oshima, N. Takegawa, Y. Miyazaki, M. Hu, P. Lin, Z. Deng, Y. Zhao, N. Sugimoto, Y. Wu
    Journal of Geophysical Research Atmospheres 114 (23) 0148-0227 2009 [Refereed][Not invited]
     
    Concentrations of elemental carbon (EC), carbon monoxide (CO), and carbon dioxide (CO< inf> 2< /inf> ) were measured in Beijing between 2005 and 2006. EC was measured every hour with a semicontinuous thermal optical analyzer. The observed concentrations were rather uniform over a distance of about 50 km from the observation site. The annual average concentrations of EC and CO were 6.9 /μgC m< sup> -3< /sup> and 1120 parts per b111ion by volume, respectively. The concentrations of these species increased with decreasing near-surface wind speed (WS). The slopes of the CO-CO< inf> 2< /inf> , EC-CO< inf> 2< /inf> and EC-CO correlations are used to estimate major EC and CO sources. In the weak wind regime (WS le 2.0 m s< sup> -1< /sup> ), the median EC, ΔEC/ΔCO < inf> 2< /inf> , and ΔEC/ΔCO (except for winter) increased in the late evening and remained high until early morning. The traffic of heavy duty diesel trucks during nighttime was about 20 times higher than that during daytime. These results indicate a dominant contribution of exhaust from diesel vehicles to the nighttime EC. In winter, the nighttime CO and ΔCO/ΔCO < inf> 2< /inf> ratio were largely higher than those in the other seasons. The most likely cause is the increase in the CO emissions from the exhaust of gasoline vehicles at low temperature. The ΔEC/ΔCO< inf> 2< /inf> ratio in winter was lower than that in fall, indicating no significant additional EC emissions. The diurnal variations of EC, CO, CO< inf> 2< /inf> , and ΔEC/ΔCO were similar between weekdays and weekends. The slopes of the CO-CO< inf> 2< /inf> -EC correlations are compared with the CO-CO< inf> 2< /inf> -EC ratios derived from a published emission inventory in the Beijing area. Copyright 2009 by the American Geophysical Union.
  • Yuzo Miyazaki, Shankar G. Aggarwal, Khem Singh, Prabhat K. Gupta, Kimitaka Kawamura
    Journal of Geophysical Research Atmospheres 114 (19) 0148-0227 2009 [Refereed][Not invited]
     
    Day- and nighttime aerosol samples were collected at an urban site in New Delhi, India, in winter 2006-2007. They were studied for low molecular weight dicarboxylic acids and related compounds, as well as total water-soluble organic carbon (TWSOC). High concentrations of diacids (up to 6.03 μg m < sup> -3< /sup> ), TWSOC, and OC were obtained, which are substantially higher than those previously observed at other urban sites in Asia. Daytime TWSOC/OC ratio (37%) was on average higher than that in nighttime (25%). In particular, more water-soluble OC (M-WSOC) to TWSOC ratio in daytime (50%) was twice higher than in nighttime (27%), suggesting that aerosols in New Delhi are photochemieally more processed in daytime to result in more water-soluble organic compounds. Oxalic acid (C< inf> 2< /inf> ) was found as the most abundant dicarboxylic acid, followed by succinic (C< inf> 4< /inf> ) and malonic (C< inf> 3< /inf> ) acids. Contributions of C< inf> 2< /inf> to M-WSOC were greater (av. 8%) in nighttime than daytime (av. 3%). Positive correlations of C< inf> 2< /inf> with malic acid (hC< inf> 4< /inf> ), glyoxylic acid (ωC< inf> 2< /inf> , and relative humidity suggest that secondary production of C< inf> 2< /inf> probably in aqueous phase is important in nighttime via the oxidation of both longer-chain diacids and ωC< inf> 2< /inf> . C< inf> 2< /inf> also showed a positive correlation with potassium (K< sup> +< /sup> ) in nighttime, suggesting that the enhanced C < inf> 2< /inf> concentrations are associated with biomass/biofuel burning. More tight, positive correlation between less water-soluble OC (L-WSOC) and K < sup> +< /sup> was found in both day- and nighttime, suggesting that L-WSOC, characterized by longer chain and/or higher molecular weight compounds, is significantly influenced by primary emissions from biomass/biofuel burning.Copyright 2009 by the American Geophysical Union.
  • N. Takegawa, T. Miyakawa, M. Watanabe, Y. Kondo, Y. Miyazaki, S. Han, Y. Zhao, D. van Pinxteren, E. Bruggemann, T. Gnauk, H. Herrmann, R. Xiao, Z. Deng, M. Hu, T. Zhu, Y. Zhang
    AEROSOL SCIENCE AND TECHNOLOGY 43 (3) 189 - 204 0278-6826 2009 [Refereed][Not invited]
     
    An Aerodyne quadrupole aerosol mass spectrometer (AMS) was deployed in China in the summer of 2006. The measurements were made in the Pearl River Delta region in July 2006 (PRD campaign) and also in Beijing in August-September 2006 (CAREBEIJING campaign). The AMS successfully measured size-resolved chemical composition of submicron non-refractory aerosol (vaporized at 600C in vacuum) with a time resolution of 10 min, although some quantification issues have been identified. We observed extremely large signals at m/z 39 (39K+) and 41 (41K+), which significantly exceeded m/z 28 (N+2) signals. We also found large signals of m/z 85 (85Rb+), 87 (87Rb+), and 133 (Cs+). Laboratory experiments suggest that the large enhancement of K+ could have been due to the presence of K-containing particles in ambient air. The interferences of alkali metals at m/z 41, 85, 87, and 133 were significant and need to be corrected for better quantification of organic aerosol. The AMS measurements are compared with other, collocated measurements: a particle-into-liquid sampler combined with an ion chromatograph (PILS-IC), a Sunset Laboratory semi-continuous carbonaceous aerosol analyzer, and a Berner impactor sampler followed by off-line ion chromatography analysis (for major inorganic ions). We have found good agreement between the AMS and the other instruments when we assume an AMS particle collection efficiency (CE) of 0.5 for the PRD data and CE = 1.0 for the CAREBEIJING data. These results suggest that the AMS CE could be significantly different in different locations. Possible factors affecting the variability in the CE values are discussed.
  • Y. Kondo, L. Sahu, M. Kuwata, Y. Miyazaki, N. Takegawa, N. Moteki, J. Imaru, S. Han, T. Nakayama, N. T. Kim Oanh, M. Hu, Y. J. Kim, K. Kita
    AEROSOL SCIENCE AND TECHNOLOGY 43 (8) 741 - 756 0278-6826 2009 [Refereed][Not invited]
     
    In principle, mass concentrations of black carbon (BC) (M-BC) can be estimated by the measurement of the light absorption coefficient of BC. Filter-based methods, which quantify the absorption coefficient (b(abs)) from the change in transmission through a filter loaded with particles, have been widely used to measure M-BC. However, reliable determination of M-BC has been very difficult because of the large variability in the mass absorption cross section (C-abs), which is the conversion factor from b(abs) to M-BC. Coating of BC by volatile compounds and the co-existence of light-scattering particles contribute to the variability of C-abs. In order to overcome this difficulty, volatile aerosol components were removed before collection of BC particles on filters by heating a section of the inlet to 400 degrees C. We made simultaneous measurements of b(abs) by two types of photometers (Particle Soot Absorption Photometer (PSAP) and Continuous Soot Monitoring System (COSMOS)) together with M-BC by an EC-OC analyzer to determine C-abs at 6 locations in Asia. C-abs was stable at 10.5 +/- 0.7 m(2) g(-1) at a wavelength of 565 nm for BC strongly impacted by emissions from vehicles and biomass burning. The stable C-abs value provides a firm basis for its use in estimating M-BC by COSMOS and PSAP with an accuracy of about 10%. For the quantitative interpretation of the ratio of the C-abs to the model-calculated C-abs*, we measured Cabs for mono-disperse nigrosin particles in the laboratory. The C-abs/C-abs* ratio was 1.4-1.9 at the 100-200 nm diameters, explaining the ratio of 1.8 for ambient BC.
  • Y. Kondo, Y. Morino, M. Fukuda, Y. Kanaya, Y. Miyazaki, N. Takegawa, H. Tanimoto, R. McKenzie, P. Johnston, D. R. Blake, T. Murayama, M. Koike
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 113 (D21) doi:10.1029/2008JD010134  2169-897X 2008/11 [Refereed][Not invited]
     
    Measurements of the major reactive nitrogen species (NOy)(i) (NOx, peroxyacyl nitrates, HNO3, and particulate nitrate (NO3-)),total reactive nitrogen (NOy), volatile organic compounds, OH and HO2, and organic aerosol were made near the urban center of Tokyo in different seasons of 2003-2004 to study the processes involving oxidized forms of reactive nitrogen and O-3. Generally, NOx constituted the dominant fraction of NOy throughout the seasons. The NOx/NOy and HNO3/NOy ratios were lowest and highest, respectively, in summer, owing to the seasonally high OH concentration. The fraction of NOy that remained in the atmosphere after emission (R-NOy) decreased with the decrease in the NOx/NOy ratio in summer and fall. It is likely that the median seasonal-diurnal variations of O-x = O-3 + NO2 were controlled by those of the background O-3 levels, photochemical O-3 formation, and vertical transport. O-x showed large increases during midday under stagnant conditions in mid-August 2004. Their in situ production rates calculated by a box model were too slow to explain the observed increases. The high O-x was likely due to the accumulation of O-x from previous days in the upper part of the boundary layer (BL) followed by transport down to near the surface by mixing after sunrise. Considering the tight correlation between O-x and secondary organic aerosol (SOA), it is likely that SOA also accumulated during the course of sea-land breeze circulation in the BL.
  • In-Jin Choi, Sang-Woo Kim, Jiyoung Kim, Soon-Chang Yoon, Man-Hae Kim, Nobuo Sugimoto, Yutaka Kondo, Yuzo Miyazaki, Kwang-Joo Moon, Jin-Seok Han
    ATMOSPHERIC ENVIRONMENT 42 (36) 8513 - 8523 1352-2310 2008/11 [Refereed][Not invited]
     
    In this study, we investigate the physio-chemical and optical properties of Asian spring continental outflow and its relation to synoptic transport patterns. Ground-based highly time-resolved measurements of aerosol chemical and physical properties, and lidar measurements of aerosol vertical distributions at Gosan, Korea during ABC-EAREX2005 have been analyzed. Two selected cases, based on PM10 and PM2.5 mass concentrations, indicate that pollution-dominant airmass preceded by the appearance of a major mineral dust plume with about 12 h time-lag. At the ground level, pollution aerosol components (NO3-, SO2-, and NH4+) showed distinct peaks first and the enhancement of soil components (Ca2+) appeared approximately 12 h later. Although lidar measurements reveal that spherical pollution particles were observed near the surface prior to a major plume of non-spherical mineral dust, elevated dust layers were simultaneously observed in the free troposphere overlying the ground-level pollution plume. Chemical transport model simulations of the horizontal distributions of dust and sulfate aerosols illustrate well the pollution plume preceding the dust-laden airmass. Backward trajectory and NCAR/PSU MM5 analysis show that the preceding pollution plume and following dust plume were consecutively transported under fast northwesterly/northerly winds formed between anticyclonic and cyclonic flows at the ground level. (c) 2008 Published by Elsevier Ltd.
  • Y. Kondo, R. C. Hudman, K. Nakamura, M. Koike, G. Chen, Y. Miyazaki, N. Takegawa, D. R. Blake, I. J. Simpson, M. Ko, K. Kita, T. Shirai, S. Kawakami
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 113 (D15) 2169-897X 2008/08 [Refereed][Not invited]
     
    The seasonal variation of ozone (O-3) in the boundary layer (BL) over the western Pacific is investigated using a chemistry-transport model. The model results for January and April-May 2002 were evaluated by comparison with PEACE aircraft observations. In January, strong northwesterlies efficiently transported NOx from the continent, leading to an O-3 increase of approximately 5-10 ppbv over a distance of about 3000 km. In April, southwesterlies dominated due to anticyclone development over the western Pacific. Along this flow, O-3 continued to be produced by NOx emitted from East Asia. This resulted in the formation of a high-O-3 (> 50 ppbv) region extending along the coastal areas of East Asia. This seasonal change in O-3 was driven in part by a change in the net O-3 production rate due to increases in solar UV and H2O. Its exact response depended on the NOx values in the BL. The net O-3 production rate increased between winter and spring over the Asian continent and decreased over the remote western Pacific. Model simulations show that about 25% of the total O-3 (of 10-20 ppbv) increase over the coastal region of Northeast Asia was due to local production from NOx emissions from China, and the rest was due to changes in background levels as well as emissions from Korea, Japan, and east Siberia. Uplift of BL air over Asia, horizontal transport in the free troposphere, and subsidence were the principal mechanisms of transporting Asian O-3 to the central and eastern North Pacific.
  • W. Hua, Z. M. Chen, C. Y. Jie, Y. Kondo, A. Hofzumahaus, N. Takegawa, C. C. Chang, K. D. Lu, Y. Miyazaki, K. Kita, H. L. Wang, Y. H. Zhang, M. Hu
    ATMOSPHERIC CHEMISTRY AND PHYSICS 8 (22) 6755 - 6773 1680-7316 2008 [Refereed][Not invited]
     
    Atmospheric hydrogen peroxide (H(2)O(2)) and organic hydroperoxides were measured from 18 to 30 July in 2006 during the PRIDE-PRD'06 campaign at Backgarden, a rural site located 48 km north of Guangzhou, a mega-city in southern China. A ground-based instrument was used as a scrubbing coil collector to sample ambient air, followed by on-site analysis by high-performance liquid chromatography (HPLC) coupled with post-column derivatization and fluorescence detection. The H(2)O(2) mixing ratio over the 13 days ranged from below the detection limit to a maximum of 4.6 ppbv, with a mean (and standard deviation) of (1.26 +/- 1.24) ppbv during the daytime (08:00-20:00 LT). Methyl hydroperoxide (MHP), with a maximum of 0.8 ppbv and a mean (and standard deviation) of (0.28 +/- 0.10) ppbv during the daytime, was the dominant organic hydroperoxide. Other organic peroxides, including bis-hydroxymethyl hydroperoxide (BHMP), peroxyacetic acid (PAA), hydroxymethyl hydroperoxide (HMHP), 1-hydroxy-ethyl hydroperoxide (1-HEHP) and ethyl hydroperoxide (EHP), were detected occasionally. The concentration of H(2)O(2) exhibited a pronounced diurnal variation on sunny days, with a peak mixing ratio in the afternoon (12:00-18:00 LT), but lacked an explicit diurnal cycle on cloudy days. Sometimes a second peak mixing ratio of H(2)O(2) was observed during the evening, suggesting that H(2)O(2) was produced by the ozonolysis of alkenes. The diurnal variation profile of MHP was, in general, consistent with that of H(2)O(2). The estimation indicated that in the morning the H(2)O(2) detected was formed mostly through local photochemical activity, with the rest probably attributable to vertical transport. It is notable that relatively high levels of H(2)O(2) and MHP were found in polluted air. The unexpectedly high level of HO(2) radicals detected in this region can account for the production of hydroperoxides, while the moderate level of NO(x) suppressed the formation of hydroperoxides. High concentrations of hydroperoxides were detected in samples of rainwater collected in a heavy shower on 25 July when a typhoon passed through, indicating that a considerable mixing ratio of hydroperoxides, particularly MHP, resided above the boundary layer, which might be transported on a regional scale and further influence the redistribution of HO(x) and RO(x) radicals. It was found that hydroperoxides, in particular H(2)O(2), play an important role in the formation of secondary sulfate in the aerosol phase, where the heterogeneous reaction might contribute substantially. A negative correlation between hydroperoxides and water-soluble organic compounds (WSOC), a considerable fraction of the secondary organic aerosol (SOA), was observed, possibly providing field evidence for the importance of hydroperoxides in the formation of SOA found in previous laboratory studies. We suggest that hydroperoxides act as an important link between sulfate and organic aerosols, which needs further study and should be considered in current atmospheric models.
  • R. M. Garland, H. Yang, O. Schmid, D. Rose, A. Nowak, P. Achtert, A. Wiedensohler, N. Takegawa, K. Kita, Y. Miyazaki, Y. Kondo, M. Hu, M. Sha, L. M. Zeng, Y. H. Zhang, M. O. Andreae, U. Poeschl
    ATMOSPHERIC CHEMISTRY AND PHYSICS 8 (17) 5161 - 5186 1680-7316 2008 [Refereed][Not invited]
     
    The scattering and absorption of solar radiation by atmospheric aerosols is a key element of the Earth's radiative energy balance and climate. The optical properties of aerosol particles are, however, highly variable and not well characterized, especially near newly emerging mega-cities. In this study, aerosol optical properties were measured at a rural site approximately 60 km northwest of the mega-city Guangzhou in southeast China. The measurements were part of the PRIDE-PRD2006 intensive campaign, covering the period of 1-30 July 2006. Scattering and absorption coefficients of dry aerosol particles with diameters up to 10 mu m (PM10) were determined with a three-wavelength integrating nephelometer and with a photoacoustic spectrometer, respectively. Averaged over the measurement campaign (arithmetic mean +/- standard deviation), the total scattering coefficients were 200 +/- 133 Mm(-1) (450 nm), 151 +/- 103 Mm(-1) (550 nm) and 104 +/- 72 Mm(-1) (700 nm) and the absorption coefficient was 34.3 +/- 26.5 Mm-1 (532 nm). The average Angstrom exponent was 1.46 +/- 0.21 (450 nm/700 nm) and the average single scattering albedo was 0.82 +/- 0.07 (532 nm) with minimum values as low as 0.5. The low single scattering albedo values indicate a high abundance, as well as strong sources, of light absorbing carbon (LAC). The ratio of LAC to CO concentration was highly variable throughout the campaign. indicating a complex mix of different combustion sources. The scattering and absorption coefficients, as well as the Angstrom exponent and single scattering albedo, exhibited pronounced diurnal cycles, which can be attributed to boundary layer mixing effects and enhanced nighttime emissions of LAC (diesel soot from regulated truck traffic). The daytime average mid-visible sin-le scattering albedo of 0.87 appears to be more suitable for climate modeling purposes than the 24-h average of 0.82, as the latter value is strongly influenced by fresh emissions into a shallow nocturnal boundary layer. In spite of high photochemical activity during daytime. we found no evidence for strong local production of secondary aerosol mass. The average mass scattering efficiencies with respect to PM10 and PM1 concentrations derived from particle size distribution measurements were 2.8 m(2) g(-1) and 4.1 m(-2) g(-1), respectively. The Angstrom exponent exhibited a wavelength dependence (curvature) that was related to the ratio of fine and coarse particle mass (PM1/PM10) as well as the surface mode diameter of the fine particle fraction. The results demonstrate consistency between in situ measurements and a remote sensing formalism with regard to the fine particle fraction and volume mode diameter, but there are also systematic deviations for the larger mode diameters. Thus we suggest that more data sets from in situ measurements of aerosol optical parameters and particle size distributions should be used to evaluate formalisms applied in aerosol remote sensing. Moreover, we observed a negative correlation between single scattering albedo and backscatter fraction, and we found that it affects the impact that these parameters have on aerosol radiative forcing efficiency and should he considered in model studies of the PRD and similarly polluted mega-city regions.
  • M. Kuwata, Y. Kondo, Y. Miyazaki, Y. Komazaki, J. H. Kim, S. S. Yum, H. Tanimoto, H. Matsueda
    ATMOSPHERIC CHEMISTRY AND PHYSICS 8 (11) 2933 - 2948 1680-7316 2008 [Refereed][Not invited]
     
    We measured the number concentrations of cloud condensation nuclei (CCN) and the size distributions of CCN/CN (CN: condensation nuclei) ratios at supersaturations (SSs) of 0.097, 0.27, 0.58, and 0.97% at Jeju Island, Korea during March-April 2005. We made simultaneous measurements of aerosol inorganic ions, water-soluble organic carbon (WSOC), organic carbon (OC), and elemental carbon (EC) in PM2.5. The CCN/CN ratios increased with increasing particle diameter, and the diameter at CCN/CN=0.5 was defined as D-50. D-50 represents the activation dry diameter of atmospheric particles. The average D-50 at SS=0.097% and 0.97% was 136+/-17 nm and 31+/-3 nm, respectively. The temporal variation of D-50 at SS=0.097% was correlated with the mass fraction of water-soluble components (inorganic ions + WSOC), indicating that the temporal variation of CCN activity was mainly controlled by changes in the water-soluble components fraction. The critical dry diameter (D-crit), which is the threshold dry diameter for CCN activation, was calculated from the observed aerosol chemical compositions by Kohler theory for comparison with D-50. The D-50 at SS=0.097% was correlated (r(2)=0.48) with calculated D-crit, although D-crit was larger than D-50 by 20-29% on average. The systematic difference between D-50 and D-crit could be caused by the size dependence of the aerosol chemical compositions or surface tension lowering caused by the mixing of water-soluble organic compounds. This difference corresponds to a 27+/-14% uncertainty in the CCN number concentration estimated from the observed particle number size distribution.
  • Yuzo Miyazaki, Yutaka Kondo, Lokesh K. Sahu, Junichi Imaru, Nobuhiko Fukushima, Minoru Kano
    JOURNAL OF ENVIRONMENTAL MONITORING 10 (10) 1195 - 1201 1464-0325 2008 [Not refereed][Not invited]
     
    We designed a continuous soot monitoring system (COSMOS) for fully automated, high-sensitivity, continuous measurement of light absorption by black carbon (BC) aerosols. The instrument monitors changes in transmittance across an automatically advancing quartz fiber filter tape using an LED at a 565 nm wavelength. To achieve measurements with high sensitivity and a lower detectable light absorption coefficient, COSMOS uses a double-convex lens and optical bundle pipes to maintain high light intensity and signal data are obtained at 1000 Hz. In addition, sampling flow rate and optical unit temperature are actively controlled. The inlet line for COSMOS is heated to 400 degrees C to effectively volatilize non-refractory aerosol components that are internally mixed with BC. In its current form, COSMOS provides BC light absorption measurements with a detection limit of 0.45 Mm(-1) (0.045 mu g m(-3) for soot) for 10 min. The unit-to-unit variability is estimated to be within +/- 1%, demonstrating its high reproducibility. The absorption coefficients determined by COSMOS agreed with those by a particle soot absorption photometer (PSAP) to within 1% (r(2) = 0.97). The precision (+/- 0.60 Mm(-1)) for 10 min integrated data was better than that of PSAP and an aethalometer under our operating conditions. These results showed that COSMOS achieved both an improved detection limit and higher precision for the filter-based light absorption measurements of BC compared to the existing methods.
  • Y. Kondo, R. C. Hudman, K. Nakamura, M. Koike, G. Chen, Y. Miyazaki, N. Takegawa, D. R. Blake, I. J. Simpson, M. Ko, K. Kita, T. Shirai, S. Kawakami
    Journal of Geophysical Research Atmospheres 113 (15) 0148-0227 2008 [Refereed][Not invited]
     
    The seasonal variation of ozone (O< inf> 3< /inf> ) in the boundary layer (BL) over the western Pacific is investigated using a chemistry-transport model. The model results for January and April-May 2002 were evaluated by comparison with PEACE aircraft observations. In January, strong northwesterlies efficiently transported NO< inf> x< /inf> from the continent, leading to an O< inf> 3< /inf> increase of approximately 5-10 ppbv over a distance of about 3000 km. In April, southwesterlies dominated due to anticyclone development over the western Pacific. Along this flow, O< inf> 3< /inf> continued to be produced by NO < inf> x< /inf> emitted from East Asia. This resulted in the formation of a high-O< inf> 3< /inf> (> 50 ppbv) region extending along the coastal areas of East Asia. This seasonal change in O< inf> 3< /inf> was driven in part by a change in the net O< inf> 3< /inf> production rate due to increases in solar UV and H < inf> 2< /inf> O. Its exact response depended on the NO< inf> x< /inf> values in the BL. The net O< inf> 3< /inf> production rate increased between winter and spring over the Asian continent and decreased over the remote western Pacific. Model simulations show that about 25% of the total O< inf> 3< /inf> (of 10-20 ppbv) increase over the coastal region of Northeast Asia was due to local production from NO< inf> x< /inf> emissions from China, and the rest was due to changes in background levels as well as emissions from Korea, Japan, and east Siberia. Uplift of BL air over Asia, horizontal transport in the free troposphere, and subsidence were the principal mechanisms of transporting Asian O< inf> 3< /inf> to the central and eastern North Pacific Copyright 2008 by the American Geophysical Union.
  • Tomoko Shirai, Yoko Yokouchi, Donald R. Blake, Kazuyuki Kita, K. Izumi, M. Koike, Y. Komazaki, Y. Miyazaki, M. Fukuda, Y. Kondo
    Journal of Geophysical Research Atmospheres 112 (24) 0148-0227 2007/12/27 [Refereed][Not invited]
     
    Eighteen C< inf> 2< /inf> -C< inf> 7< /inf> NMHCs (nonmethane hydrocarbons) were measured hourly during the Integrated Measurement Program for Aerosol and Oxidant Chemistry in Tokyo (IMPACT) measurement campaigns conducted in central Tokyo during four different periods (summer/autumn of 2003 and winter/summer of 2004). The ambient atmospheric concentrations of NMHCs showed an inverse correlation with wind speed and mixing height and were significantly affected by mesoscale weather conditions. The mixing ratio of isoprene tightly correlated with solar flux and temperature in summer, as it was dominantly emitted by the local vegetation. All the observed NMHCs except isoprene showed high correlation with each other in winter (r< sup> 2< /sup> > 0.5), suggesting concurrent accumulation under stagnant condition and common sources. Emission ratios were calculated on the basis of the correlation with carbon monoxide and ethyne. Compared to the typical winter NMEC composition, during summer there was a significant increase (up to 7 times higher than wintertime) of C< inf> 4< /inf> -C< inf> 5< /inf> alkanes from ftiel evaporation of C< inf> 2< /inf> -C< inf> 3< /inf> alkenes, n-hexane and benzene from chemical industry and of toluene from local manufacturers, reflecting the temperature dependence of these evaporative emissions. In addition to the online measurements in Tokyo, canister sampling at a suburban site (Kisai) followed by multidimensional GC analyses was conducted during the summer campaign in 2004. The atmospheric concentrations of longer-lived compounds (≥ several days) at Kisai showed the buildup under sea breeze circulation. The average ambient, concentration of toluene was 2 times higher than that in central Tokyo, likely because of substantial emissions from local industries as reported in the prefectural statistics. Copyright 2007 by the American Geophysical Union.
  • Tomoko Shirai, Yoko Yokouchi, Donald R. Blake, Kazuyuki Kita, K. Izumi, M. Koike, Y. Komazaki, Y. Miyazaki, M. Fukuda, Y. Kondo
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 112 (D24) 2169-897X 2007/12 [Refereed][Not invited]
     
    [1] Eighteen C-2-C-7 NMHCs (nonmethane hydrocarbons) were measured hourly during the Integrated Measurement Program for Aerosol and Oxidant Chemistry in Tokyo (IMPACT) measurement campaigns conducted in central Tokyo during four different periods (summer/autumn of 2003 and winter/summer of 2004). The ambient atmospheric concentrations of NMHCs showed an inverse correlation with wind speed and mixing height and were significantly affected by mesoscale weather conditions. The mixing ratio of isoprene tightly correlated with solar flux and temperature in summer, as it was dominantly emitted by the local vegetation. All the observed NMHCs except isoprene showed high correlation with each other in winter (r(2) > 0.5), suggesting concurrent accumulation under stagnant condition and common sources. Emission ratios were calculated on the basis of the correlation with carbon monoxide and ethyne. Compared to the typical winter NMHC composition, during summer there was a significant increase (up to 7 times higher than wintertime) of C-4-C-5 alkanes from fuel evaporation; of C-2-C-3 alkenes, n-hexane and benzene from chemical industry; and of toluene from local manufacturers, reflecting the temperature dependence of these evaporative emissions. In addition to the online measurements in Tokyo, canister sampling at a suburban site (Kisai) followed by multidimensional GC analyses was conducted during the summer campaign in 2004. The atmospheric concentrations of longer-lived compounds (>= several days) at Kisai showed the buildup under sea breeze circulation. The average ambient concentration of toluene was 2 times higher than that in central Tokyo, likely because of substantial emissions from local industries as reported in the prefectural statistics.
  • Yuzo Miyazaki, Yutaka Kondo, Sunghee Han, Makoto Koike, Daisuke Kodama, Yuichi Komazaki, Hiroshi Tanimoto, Hidekazu Matsueda
    Journal of Geophysical Research Atmospheres 112 (22) 0148-0227 2007/11/27 [Refereed][Not invited]
     
    Semicontinuous measurements of water-soluble organic carbon (WSOC) and organic carbon (OC) in PM< inf> 2.5< /inf> were made at Gosan, Korea, in March-April 2005. On average, the WSOC/OC mass ratio for all air masses observed at Gosan was 0.30 ± 0.12. WSOC correlated well with CO (r< sup> 2< /sup> = 0.54) in Chinese outflow, suggesting that a major part of the observed WSOC and/or their precursors was of combustion origin. The relationship between the increase of WSOC and O< inf> 3< /inf> suggests that the observed WSOC was mostly secondary product. To interpret the measured organic compounds, thermal analyses of organic standards were made in the laboratory. Thermograms of a single standard of water-soluble organic species showed that carbon that evolved at high temperatures (600°-870°C) was generally associated with water-soluble compounds having high molecular weights (MWs) on the order of hundreds, while carbon that evolved at low temperatures (< 300°C) generally had MWs of less than ∼180 g mol< sup> -1< /sup> . Positive matrix factorization (PMF) analysis revealed three organic compound groups (low, medium, and highly refractory compounds) based on the OC thermograms. On average, highly and low refractory compound groups accounted for 79% and 21% of the WSOC mass, respectively, at Gosan. Highly refractory compound groups significantly contributed to WSOC regardless of air mass origin. The results of the laboratory experiments imply that a large fraction of these highly refractory compound groups was likely associated with high MW compounds. For water-insoluble organic carbon(=OC-WSOC), medium and low refractory compound groups accounted for 60% and 40%, respectively, consistent with the results of the laboratory experiments. Copyright 2007 by the American Geophysical Union.
  • Yuzo Miyazaki, Yutaka Kondo, Sunghee Han, Makoto Koike, Daisuke Kodama, Yuichi Komazaki, Hiroshi Tanimoto, Hidekazu Matsueda
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 112 (D22) doi:10.1029/2007JD009116  2169-897X 2007/11 [Refereed][Not invited]
     
    [1] Semicontinuous measurements of water-soluble organic carbon (WSOC) and organic carbon (OC) in PM2.5 were made at Gosan, Korea, in March-April 2005. On average, the WSOC/OC mass ratio for all air masses observed at Gosan was 0.30 +/- 0.12. WSOC correlated well with CO (r(2) = 0.54) in Chinese outflow, suggesting that a major part of the observed WSOC and/or their precursors was of combustion origin. The relationship between the increase of WSOC and O-3 suggests that the observed WSOC was mostly secondary product. To interpret the measured organic compounds, thermal analyses of organic standards were made in the laboratory. Thermograms of a single standard of water-soluble organic species showed that carbon that evolved at high temperatures (600 degrees-870 degrees C) was generally associated with water-soluble compounds having high molecular weights (MWs) on the order of hundreds, while carbon that evolved at low temperatures (<300 degrees C) generally had MWs of less than similar to 180 g mol(-1). Positive matrix factorization (PMF) analysis revealed three organic compound groups (low, medium, and highly refractory compounds) based on the OC thermograms. On average, highly and low refractory compound groups accounted for 79% and 21% of the WSOC mass, respectively, at Gosan. Highly refractory compound groups significantly contributed to WSOC regardless of air mass origin. The results of the laboratory experiments imply that a large fraction of these highly refractory compound groups was likely associated with high MW compounds. For water-insoluble organic carbon(=OC-WSOC), medium and low refractory compound groups accounted for 60% and 40%, respectively, consistent with the results of the laboratory experiments.
  • M. Koike, Y. Kondo, K. Kita, N. Takegawa, N. Nishi, T. Kashihara, S. Kawakami, S. Kudoh, D. Blake, T. Shirai, B. Liley, M. Ko, Y. Miyazaki, Z. Kawasaki, T. Ogawa
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 112 (D18) 2169-897X 2007/09 [Refereed][Not invited]
     
    The Biomass Burning and Lightning Experiment phase C (BIBLE-C) aircraft mission was carried out near Darwin, Australia ( 12 degrees S, 131 degrees E) in December 2000. This was the first aircraft experiment designed to estimate lightning NO production rates in the tropics, where production is considered to be most intense. During the two flights ( flights 10 and 13 made on December 9 and 11-12, respectively) enhancements of NOx ( NO + NO2) up to 1000 and 1600 parts per trillion by volume (pptv, 10-s data) were observed at altitudes between 11.5 and 14 km. The Geostationary Meteorological Satellite (GMS) cloud ( brightness temperature) data and ground-based lightning measurements by the Global Positioning and Tracking System (GPATS) indicate that there were intensive lightning events over the coast of the Gulf of Carpentaria, which took place upstream from our measurement area 10 to 14 h prior to the measurements. For these two flights, air in which NOx exceeded 100 pptv extended over 620 x 140 and 400 x 170 km(2) ( wind direction x perpendicular direction), respectively, suggesting a significant impact of lightning NO production on NOx levels in the tropics. We estimate the amount of NOx observed between 11.5 and 14 km produced by the thunderstorms to be 3.3 and 1.8 x 10(29) NO molecules for flights 10 and 13, respectively. By using the GPATS lightning flash count data, column NO production rates are estimated to be 1.9-4.4 and 21-49 x 10(25) NO molecules per single flash for these two flight data sets. In these estimations, it is assumed that the column NO production between 0 and 16 km is greater than the observed values between 11.5 and 14 km by a factor of 3.2, which is derived using results reported by Pickering et al. (1998). There are however large uncertainties in the GPATS lightning data in this study and care must be made when the production rates are referred. Uncertainties in these estimates are discussed. The impact on the ozone production rate is also described.
  • M. Shiraiwa, Y. Kondo, N. Moteki, N. Takegawa, Y. Miyazaki, D. R. Blake
    GEOPHYSICAL RESEARCH LETTERS 34 (16) 0094-8276 2007/08 [Refereed][Not invited]
     
    The evolution of the mixing state of black carbon aerosol ( BC) was investigated using a single-particle soot photometer ( SP2) in polluted air transported from Tokyo. Ground-based measurements of aerosols and trace gases were conducted at a suburban site ( Kisai) 50 km north of Tokyo during July -August 2004. The ratio of 2-pentyl nitrate ( 2-PeONO(2)) to n-pentane ( n-C5H12) was used to derive the photochemical age. According to the SP2 measurement, the number fraction of thickly coated BC ( Shell/ Corel Ratio > ca. 2) with a core diameter of 180 nm increased at the rate of 1.9% h(-1), as the photochemical clock proceeded under land-sea breeze circulation. Positive matrix factorization was applied to investigate the time-dependent contributions of different coating materials using the mass concentrations of sulfate, nitrate, and organics measured using an aerosol mass spectrometer. The main coating materials found in this study were sulfate and organics.
  • N. Moteki, Y. Kondo, Y. Miyazaki, N. Takegawa, Y. Komazaki, G. Kurata, T. Shirai, D. R. Blake, T. Miyakawa, M. Koike
    GEOPHYSICAL RESEARCH LETTERS 34 (11) 0094-8276 2007/06 [Refereed][Not invited]
     
    We report the evolution of the mixing state of black carbon ( BC) particles in urban plumes measured by an airborne single particle soot photometer. The aircraft observations were conducted over the ocean near the coast of Japan in March 2004. The number fraction of coated BC particles with a core diameter of 180 nmincreased from 0.35 to 0.63 within 12 hours ( h), namely 2.3% h(-1), after being emitted from the Nagoya urban area in Japan. BC particles with a core diameter of 250 nm increased at the slower rate of 1.0% h(-1). The increase in coated BC particles was associated with increases in non-sea salt sulfate and water-soluble organic carbon by a factor of approximately two, indicating that these compounds contributed to the coating on the BC particles. These results give direct evidence that BC particles become internally mixed on a time scale of 12 h in urban plumes.
  • Min-Suk Bae, Chun-Sang Hong, Young J. Kim, Jin-Seok Han, Kwang-Ju Moon, Yutaka Kondo, Yuichi Komazaki, Yuzo Miyazaki
    ATMOSPHERIC ENVIRONMENT 41 (13) 2791 - 2803 1352-2310 2007/04 [Refereed][Not invited]
     
    A formal intercomparison of fine particle elemental (black) carbon is conducted involving three real-time semicontinuous measurement systems. Two-hourly interval time-resolved measurements of organic carbon (OC) and elemental carbon (EC) were performed at the Gosan site, Korea during Atmospheric Brown Clouds-East Asian Regional Experiment 2005 (ABC-EAREX2005) campaign. They were operated by the same semi-continuous field carbon instruments of Sunset Laboratory (thermal optical transmittance) in PM2.5 particulate. However, their thermal protocols (four and two steps for OC and five and two steps for EC) were different. The co-located 1 min black carbon (BC) concentrations were compared by an Aethalometer for an intercomparison study. As a result, the poor R-2 of OC between two different temperature protocols suggested that OC can be significantly more biased by the slight differences of maximum temperature (870 and 840 degrees C) and a number of temperature steps (four steps and two steps) with their hold times. However, EC that is a smaller fraction of total carbon (TC) shows the good agreement between two different protocols, which are under a mixture of 2% O-2 and 98% He in six temperature steps and two temperature steps as max as 900 and 880 degrees C with the slope of 1.05 +/- 0.15 (R-2 of 0.98). The different slopes between EC and BC, which show the range of 1.23-1.61, demonstrate the variability of the attenuation coefficient of the BC particulate. (C) 2006 Elsevier Ltd. All rights reserved.
  • Y. Kondo, Y. Miyazaki, N. Takegawa, T. Miyakawa, R. J. Weber, J. L. Jimenez, Q. Zhang, D. R. Worsnop
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 112 (D1) doi:10.1029/2006JD007056  2169-897X 2007/01 [Refereed][Not invited]
     
    [1] Submicron organic aerosol was measured simultaneously with an Aerodyne aerosol mass spectrometer (AMS) and a particle-into-liquid sampler (PILS) capable of measuring water-soluble organic carbon (WSOC) during the winter and summer of 2004 in Tokyo. Both techniques are being used to investigate the formation of secondary organic aerosol (SOA), and the combined data sets provide unique insights. In summer, about 80% (40-65%) of organic aerosols were oxygenated when scaled by total (carbon) mass concentration, due to high photochemical activity, leading to the active formation of SOA. In winter the fraction of oxygenated organic aerosol is reduced to 39% (total mass base) and 23% ( carbon mass base). Previous AMS studies have shown that signals at m/z 44 of the AMS mass spectra of ambient aerosols are dominated by COO+, which typically originates from oxygenated organic aerosols (OOA). The signals at m/z 44 and the derived OOA mass concentrations were highly correlated with WSOC (r(2) = 0.78-0.91) throughout these seasons, indicating that OOA and WSOC were very similar in their chemical characteristics. Approximately 88 +/- 29% of OOA was found to be water soluble on the basis of the comparison of the WSOC concentrations with those of oxygenated organic carbon (OOC) derived from the AMS data.
  • Y. Miyazaki, Y. Kondo, N. Takegawa, Y. Komazaki, M. Fukuda, K. Kawamura, M. Mochida, K. Okuzawa, R. J. Weber
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 111 (D23) doi:10.1029/2006JD007125  2169-897X 2006/12 [Refereed][Not invited]
     
    [1] Semicontinuous measurements of submicron water-soluble organic carbon (WSOC) aerosol were made simultaneously with organic carbon (OC) and elemental carbon (EC) in the Tokyo urban area in winter, summer, and fall 2004. The measurements of WSOC and OC/EC were made every 6 min and 1 hour, respectively, using a particle-into-liquid sampler (PILS) with a total organic carbon (TOC) analyzer and with an EC-OC analyzer using a thermal-optical technique. The PILS and 12-hour integrated filter measurements of WSOC agreed to within 12%. The WSOC mass concentrations and WSOC/OC ratio showed diurnal variations with peaks at 1200-1400 LT in summer and later in the afternoon in winter. On average, the WSOC/OC ratio was 0.20 and 0.35 mu g C/mu g C for winter and summer/late fall, respectively. The difference in the winter and summer frequency distributions of the WSOC/OC ratio suggests that the sampled air masses in summer and fall were more photochemically processed than those in winter. Secondary organic carbon (SOC) concentrations were estimated using the EC-tracer method. The measured WSOC was highly correlated with the derived SOC (r(2) = 0.61-0.79), with WSOC/SOC slopes of 0.67 to 0.75 mu g C/mu g C for each season. These results suggest that the WSOC and SOC were similar in their chemical characteristics in this study. Water-insoluble organic carbon (WIOC) ( = OC-WSOC) correlated well with EC and CO (r(2) = 0.59-0.73). The diurnally averaged WIOC/EC ratios were nearly constant (1.1 +/- 0.1 mu g C/mu g C) throughout the study periods, suggesting that motor vehicle emissions were an important source of WIOC. A dominant portion ( about 90% or more) of the POC was water-insoluble, consistent with previous studies of POC.
  • Y. Morino, Y. Kondo, N. Takegawa, Y. Miyazaki, K. Kita, Y. Komazaki, M. Fukuda, T. Miyakawa, N. Moteki, D. R. Worsnop
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 111 (D15) 2169-897X 2006/08 [Refereed][Not invited]
     
    [ 1] Ground-based measurements of gas-phase nitric acid (HNO3) and particulate nitrate (NO3-) were performed in Tokyo during 2003 - 2004. These measurements provide a comprehensive data set for investigating the diurnal and seasonal variations of gas-phase HNO3 and particulate NO3- and the thermodynamic equilibrium of these compounds. HNO3 and NO3- have distinct diurnal and seasonal variations, especially in summer. This study shows that the thermodynamic equilibrium of HNO3 and NO3- and the production rate of total nitrate (TNO3 = HNO3 + NO3-) are the major controlling factors affecting these seasonal and diurnal variations. A thermodynamic equilibrium model (ISORROPIA) is newly coupled with a one-dimensional (1-D) model to take into account the effect of vertical mixing during daytime on the partitioning of HNO3 and NO3- by constraining the TNO3 concentrations to the observations. The 1-D model reproduces the NO3-/TNO3 ratios observed during daytime, whereas the equilibrium model significantly underestimates these ratios. The agreement between the observed and calculated NO3-/TNO3 ratios is improved over the observed temperature range (1 degrees- 34 degrees C) and relative humidity (18 - 95%) by the 1-D model. These results suggest the importance of vertical mixing in determining HNO3-NO3- partitioning in the boundary layer. It is also found that the mass accommodation coefficient for HNO3 needs to be approximately 0.1 to explain the observed HNO3-NO3- partitioning at the surface.
  • N. Takegawa, T. Miyakawa, Y. Kondo, D. R. Blake, Y. Kanaya, M. Koike, M. Fukuda, Y. Komazaki, Y. Miyazaki, A. Shimono, T. Takeuchi
    GEOPHYSICAL RESEARCH LETTERS 33 (15) 0094-8276 2006/08 [Refereed][Not invited]
     
    Ground-based measurements of aerosols and trace gases were conducted at an urban site in Tokyo (Komaba) and a site 50 km to the north (Kisai) during July - August 2004. An Aerodyne aerosol mass spectrometer (AMS) was deployed at each measurement site to investigate the chemical evolution of submicron organic aerosol (OA) in polluted air. The mass concentrations of OA at the Kisai site were systematically higher than those at the Komaba site and were correlated with ozone under southerly conditions. The rate of increase of OA at the Kisai site is investigated using the photochemical age derived from the ratio of alkyl nitrates to their parent hydrocarbons. The OA concentrations in processed air ( age of 8 - 16 h) were 4 - 5 times larger than those in fresh emissions ( age similar to 0), suggesting that the OA concentrations can be significantly enhanced within similar to 0.5 days under conditions of high photochemical activity.
  • Kazuyuki Kita, Yu Morino, Yutaka Kondo, Yuichi Komazaki, Nobuyuki Takegawa, Yuzo Miyazaki, Jun Hirokawa, Shigeru Tanaka, Thomas L. Thompson, Ru-Shan Gao, David W. Fahey
    JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY 23 (8) 1104 - 1113 0739-0572 2006/08 [Refereed][Not invited]
     
    A chemical ionization mass spectrometer (CIMS) instrument has been developed for high-precision measurements of gaseous nitric acid (HNO3) specifically under high- and variable-humidity conditions in the boundary layer. The instrument's background signals (i.e., signals detected when HNO3-free air is measured), which depend on the humidity and HNO3 concentration of the sample air, are the most important factor affecting the limit of detection (LOD). A new system to provide HNO3-free air without changing both the humidity and the pressure of the sampled air was developed to measure the background level accurately. The detection limit was about 23 parts per trillion by volume (pptv) for 50-s averages. Field tests, including an intercomparison with the diffusion scrubber technique, were carried out at a surface site in Tokyo, Japan, in October 2003 and June 2004. A comparison between the measured concentrations of HNO3 and particulate nitrate indicated that the interference from particulate nitrate was not detectable (i.e., less than about 1%). The intercomparison indicated that the two independent measurements of HNO3 agreed to within the combined uncertainties of these measurements. This result demonstrates that the CIMS instrument developed in this study is capable of measuring HNO3 mixing ratios with the precision, accuracy, and time resolution required for atmospheric science.
  • Y. Kondo, Y. Komazaki, Y. Miyazaki, N. Moteki, N. Takegawa, D. Kodama, S. Deguchi, M. Nogami, M. Fukuda, T. Miyakawa, Y. Morino, M. Koike, Hiromu Sakurai, Kensei Ehara
    Journal of Geophysical Research Atmospheres 111 (12) 0148-0227 2006/06/27 [Refereed][Not invited]
     
    Mass concentrations of elemental carbon (EC) in fine mode and mixing ratios of carbon monoxide (CO) were measured at the University of Tokyo campus in Tokyo in different seasons in 2003-2005. Measurements of EC were made using a semicontinuous thermal-optical analyzer. The mass concentrations of nonvolatile aerosol measured by the calibrated scanning mobility particle sizer combined with a heated inlet agreed with the independent EC measurements with a systematic difference of about 4%, demonstrating that the mass concentrations of nonvolatile aerosol well represent those for EC. A majority of the nonvolatile aerosol and therefore EC mass concentration was in volume equivalent diameters between 50 and 200 nm, peaking at around 130 nm. The correlation of EC and CO was generally compact throughout the measurement period because of the similarity in sources. The slope of the EC-CO correlation (ΔEC/ΔCO) is therefore a useful parameter in validating EC emission inventories. The EC concentration and ΔEC/ΔCO showed distinct diurnal variation. On weekdays, EC and ΔEC/ΔCO reached maximum values of about 3 μg m< sup> -3< /sup> and 9 ng m< sup> -3< /sup> /parts per billion by volume, respectively, in the early morning (0400-0800 local time), when the traffic density of heavy-duty trucks with diesel engines was highest. In addition, these values were lower by a factor of 2 on Sundays. The heavy truck traffic showed similar diurnal and weekday/weekend variations, indicating that exhaust from diesel engines is an important source of EC. Monthly mean ΔEC/ΔCO showed a seasonal variation, reaching broad maximum values in spring-autumn and reaching minimum values in midwinter, following the seasonal variation in temperature, as observed in Maryland, United States (Chen et al., 2001). This temperature dependence is likely due to the temperature dependence of EC emissions from diesel engines on intake air temperature. More stringent regulation of emissions of particles from diesel cars started in the Tokyo Metropolitan Area in October 2003. The ΔEC/ΔCO values did not change, however, exceeding the natural variability (10%) after 1 year from the start of the new regulations, when the temperature dependence is taken into account. This indicates that the regulation of particle emissions in the Tokyo Metropolitan Area was not effective in reducing the EC concentrations after 1 year. Copyright 2006 by the American Geophysical Union.
  • Y. Kondo, Y. Komazaki, Y. Miyazaki, N. Moteki, N. Takegawa, D. Kodama, S. Deguchi, M. Nogami, M. Fukuda, T. Miyakawa, Y. Morino, M. Koike, H. Sakurai, K. Ehara
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 111 (D12) 2169-897X 2006/06 [Refereed][Not invited]
     
    [1] Mass concentrations of elemental carbon (EC) in fine mode and mixing ratios of carbon monoxide ( CO) were measured at the University of Tokyo campus in Tokyo in different seasons in 2003 - 2005. Measurements of EC were made using a semicontinuous thermal-optical analyzer. The mass concentrations of nonvolatile aerosol measured by the calibrated scanning mobility particle sizer combined with a heated inlet agreed with the independent EC measurements with a systematic difference of about 4%, demonstrating that the mass concentrations of nonvolatile aerosol well represent those for EC. A majority of the nonvolatile aerosol and therefore EC mass concentration was in volume equivalent diameters between 50 and 200 nm, peaking at around 130 nm. The correlation of EC and CO was generally compact throughout the measurement period because of the similarity in sources. The slope of the EC-CO correlation (Delta EC/Delta CO) is therefore a useful parameter in validating EC emission inventories. The EC concentration and Delta EC/Delta CO showed distinct diurnal variation. On weekdays, EC and Delta EC/Delta CO reached maximum values of about 3 mu g m(-3) and 9 ng m(-3)/parts per billion by volume, respectively, in the early morning ( 0400 - 0800 local time), when the traffic density of heavy-duty trucks with diesel engines was highest. In addition, these values were lower by a factor of 2 on Sundays. The heavy truck traffic showed similar diurnal and weekday/weekend variations, indicating that exhaust from diesel engines is an important source of EC. Monthly mean Delta EC/Delta CO showed a seasonal variation, reaching broad maximum values in spring- autumn and reaching minimum values in midwinter, following the seasonal variation in temperature, as observed in Maryland, United States ( Chen et al., 2001). This temperature dependence is likely due to the temperature dependence of EC emissions from diesel engines on intake air temperature. More stringent regulation of emissions of particles from diesel cars started in the Tokyo Metropolitan Area in October 2003. The Delta EC/Delta CO values did not change, however, exceeding the natural variability (10%) after 1 year from the start of the new regulations, when the temperature dependence is taken into account. This indicates that the regulation of particle emissions in the Tokyo Metropolitan Area was not effective in reducing the EC concentrations after 1 year.
  • Y Miyazaki, Y Kondo, N Takegawa, RJ Weber, M Koike, K Kita, M Fukuda, Y Ma, AD Clarke, VN Kapustin, F Flocke, AJ Weinheimer, M Zondlo, FL Eisele, DR Blake, B Liley
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 110 (D15) doi:10.1029/2004JD005502  2169-897X 2005/08 [Refereed][Not invited]
     
    [1] Simultaneous measurements of speciated, total reactive nitrogen (NOy) and particulate NO3- ( particle diameter < 1.3 mm) were made on board the NASA P-3B aircraft over the western Pacific in February - April 2001 during the Transport and Chemical Evolution over the Pacific (TRACE-P) experiment. Gas-phase and particulate NOy was measured using a gold tube catalytic converter. For the interpretation of particulate NOy, conversion efficiencies of particulate NH4NO3, KNO3, NaNO3, and Ca(NO3)(2) were measured in the laboratory. Only NH4NO3 showed quantitative conversion, and its conversion efficiency was as high as that for HNO3. NOy measured on board the aircraft was found to be systematically higher by 10 - 30% than the sum of the individual NOy gas components (Sigma(NOy)(i)) at 0 - 4 km. Particulate NO3- concentrations measured by a particle-into-liquid sampler (PILS) were nearly equal to NOy - Sigma(NOy)(i) under low-dust-loading conditions. The PILS data showed that the majority of the particulate NO3- was in the form of NH4NO3 under these conditions, suggesting that NH4NO3 particles were quantitatively converted to detectable NO by the NOy converter, consistent with the laboratory experiments. The contribution of particulate NO3- to NOy was most important at 0 - 2 km, where NO3- constituted 10 - 30% of NOy during TRACE-P. On average, the amounts of particulate NO3- and gas-phase HNO3 were comparable in this region.
  • N Takegawa, Y Miyazaki, Y Kondo, Y Komazaki, T Miyakawa, JL Jimenez, JT Jayne, DR Worsnop, JD Allan, RJ Weber
    AEROSOL SCIENCE AND TECHNOLOGY 39 (8) 760 - 770 0278-6826 2005/08 [Refereed][Not invited]
     
    The Aerodyne Aerosol Mass Spectrometer (AMS) provides size-resolved chemical composition of non-refractory ( vaporized at 600 degrees C under vacuum) submicron aerosols with a time resolution of the order of minutes. Ambient measurements were performed in Tokyo between February 2003 and February 2004. We present intercomparisons of the AMS with a Particle-Into-Liquid Sampler combined with an Ion Chromatography analyzer (PILS-IC) and a Sunset Laboratory semi-continuous thermal-optical carbon analyzer. The temperature of the AMS inlet manifold was maintained at > 10 degrees C above the ambient dew point to dry particles in the sample air ( relative humidity ( RH) in the inlet < 53%). Assuming a particle collection efficiency of 0.5 for the AMS, the mass concentrations of inorganic species ( nitrate, sulfate, chloride, and ammonium) measured by the AMS agree with those measured by the PILS-IC to within 26%. The mass concentrations of organic compounds measured by the AMS correlate well with organic carbon (OC) mass measured by the Sunset Laboratory carbon analyzer (r(2) = 0.67-0.83). Assuming the same collection efficiency of 0.5 for the AMS organics, the linear regression slope is found to be 1.8 in summer and 1.6 in fall. These values are consistent with expected ratios of organic matter ( OM) to OC in urban air.
  • N. Takegawa, Y. Kondo, M. Koike, G. Chen, T. Machida, T. Watai, D. R. Blake, D. G. Streets, J. H. Woo, G. R. Carmichael, K. Kita, Y. Miyazaki, T. Shirai, J. B. Liley, T. Ogawa
    Journal of Geophysical Research D: Atmospheres 109 (23) 1 - 16 0148-0227 2004/12/16 [Refereed][Not invited]
     
    The Pacific Exploration of Asian Continental Emission Phase A (PEACE-A) aircraft measurement campaign was conducted over the western Pacific in January 2002. Correlations of carbon monoxide (CO) with carbon dioxide (CO2) and back trajectories are used to identify plumes strongly affected by Asian continental emissions. ΔCO/ΔCO2 ratios (i.e., linear regression slopes of CO-CO2) in the plumes generally fall within the variability range of the CO/CO2 emission ratios estimated from an emission inventory for east Asia, demonstrating the consistency between the aircraft measurements and the emission characterization. Removal rates of reactive nitrogen (NOx and NOy) for the study region (altitude < 4 km, 124°-140°E, 25°-45°N) are estimated using the correlation with CO2, the photochemical age of the plumes, and the NOx/ CO2 emission ratio derived from the emission inventory. The plume age is estimated from the rates of hydrocarbon decay and hydroxyl radical (OH) concentration calculated using a constrained photochemical box model. The average lifetime of NOx is estimated to be 1.2 ± 0.4 days. Possible processes controlling the NOx lifetime are discussed in conjunction with results from earlier studies. The average lifetime of NOy is estimated to be 1.7 ± 0.5 days, which is comparable to the NOy lifetime of 1.7-1.8 days that has been previously reported for outflow from the United States. This similarity suggests the importance of chemical processing near the source regions in determining the NOy abundance. Copyright 2004 by the American Geophysical Union.
  • N. Oshima, M. Koike, H. Nakamura, Y. Kondo, N. Takegawa, Y. Miyazaki, D. R. Blake, T. Shirai, K. Kita, S. Kawakami, T. Ogawa
    Journal of Geophysical Research D: Atmospheres 109 (23) 1 - 17 0148-0227 2004/12/16 [Refereed][Not invited]
     
    The Pacific Exploration of Asian Continental Emission phase B (PEACE-B) aircraft mission was conducted over the western Pacific during April-May 2002. During several flights large enhancements of CO greater than 200 parts per billion by volume (ppbv) were served at altitudes between 5 and 10 km. In this paper, we describe vertical transport mechanisms over east Asia that were responsible for these enhancements, using the European Centre for Medium-Range Weather Forecasts (ECMWF) meteorological data and infrared cloud data obtained by the Geostationary Meteorological Satellite (GMS)-5. A case study for the highest CO event shows that it was likely due to vertical transport of pollutants caused by deep cumulus convection along a quasi-stationary frontal zone, which was formed over central China (around the Yangtze River at 30°N). In the mean meteorological field during the PEACE-B period, the warm, moist low-level southerlies converged into the frontal zone, sustaining cross-frontal temperature and moisture contrasts. Along the frontal zone, the mean vertical motion was distinctively upward, and a subtropical jet aloft was found to transport uplifted air parcels efficiently into the western Pacific. In this study, criteria to identify deep convection are defined using both the ECMWF and GMS data. The results show that convective activity, which was generally high below the subtropical jet, played an important role in producing updrafts over central China. The convective transport resulted mainly from a limited number of episodes, each of which followed the development of a weak cyclonic disturbance. Back trajectories of air parcels sampled at altitudes between 4 and 13 km on board the aircraft during PEACE-B show that among the air parcels originating from the 800-hPa level or below, 69% were likely to have undergone convective uplifting. In addition to convection, sloping isentropes often observed along the quasi-stationary jet axis yielded persistent slow quasi-adiabatic uplifting of air over the Far East, which was occasionally intensified with a classical warm conveyor belt (WCB) airstream on the passage of migratory cyclonic disturbances. Meteorological conditions during PEACE-B were thus favorable for the upliffing of boundary layer air influenced by anthropogenic emissions over central China. These results are consistent with the relatively high levels of Halon 1211 (CF2ClBr), a good tracer of Chinese anthropogenic emissions, observed in the air parcels that were likely uplifted in the frontal zone. Coyright 2004 by the American Geophysical Union.
  • Y. Kondo, K. Nakamura, G. Chen, N. Takegawa, M. Koike, Y. Miyazaki, K. Kita, J. Crawford, M. Ko, D. R. Blake, S. Kawakami, T. Shirai, B. Liley, Y. Wang, T. Ogawa
    Journal of Geophysical Research D: Atmospheres 109 (23) 1 - 19 0148-0227 2004/12/16 [Refereed][Not invited]
     
    Aircraft measurements of ozone (O3) and its precursors, including NO, CO, H2O, and nonmethane hydrocarbons (NMHCs), were made over the western Pacific in the 20° - 45°N latitude range in January and April-May 2002 during the Pacific Exploration of Asian Continental Emission (PEACE)-A and B campaigns. These measurements have provided data sets that, in combination with Transport and Chemical Evolution over the Pacific (TRACE-P) data taken in March 2001, enable studies of O3 photochemistry from winter to late spring. A photochemical box model is used to calculate ozone formation (F(O3)) and destruction (D(O3)) rates constrained by the observed species concentrations. The values of F(O3) and D(O3) are controlled directly by NO, J(O1D) (O3 photolysis frequency), H2O, OH, and HO2. Changes in HO2 concentration cause corresponding changes in both F(O3) and D(O3) leading to their coupling. Concentrations of these species, which are strongly influenced by photochemistry and transport from the Asian continent, underwent large seasonal variations. In the boundary layer (0-3 km), NO was much higher in January than in April-May, because of stronger winds, lower convective activities, and lower oxidation rates by OH in winter. The net O3 formation rate, given by P(O3) = F(O3) - D(O3), was largely positive in the boundary layer at 30°-45°N (1.5-4 ppbv d-1) in January, mainly because of high NO and low H2O values. Net O3 formation continued from January to the end of March, demonstrating that the western Pacific is an important O3 source region during this season. Net O3 formation nearly ceased by late April/May because of the decrease in NO and the increase in H2O. In the latitude range of 20°-30°N, P(O3) in the boundary layer was positive in January and turned negative by March. The earlier transition was mainly due to lower NO and higher H2O concentrations, combined with weaker transport and higher temperatures than those at 30°-45°N. The upper troposphere (6-12 km) has been shown to be a region of net O3 formation throughout most of the year because of high NO and low H2O. The present study illustrates that a decrease in the net O3 formation rate at 20°-45°N latitude from winter to late spring is explained systematically by the increases in J(O1D), H2O, OH, and HO2 (primarily due to increases in temperature and solar radiation) and the decrease in NO (primarily due to decrease in transport from the Asian continent). Differences in the seasonal variation of O3 photochemistry observed over the North American continent are interpreted in terms of the differences in factors controlling O3 formation and destruction. Copyright 2004 by the American Geophysical Union.
  • N Oshima, M Koike, H Nakamura, Y Kondo, N Takegawa, Y Miyazaki, DR Blake, T Shirai, K Kita, S Kawakami, T Ogawa
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 109 (D23) 2169-897X 2004/12 [Refereed][Not invited]
     
    The Pacific Exploration of Asian Continental Emission phase B (PEACE-B) aircraft mission was conducted over the western Pacific during April-May 2002. During several flights, large enhancements of CO greater than 200 parts per billion by volume (ppbv) were observed at altitudes between 5 and 10 km. In this paper, we describe vertical transport mechanisms over east Asia that were responsible for these enhancements, using the European Centre for Medium-Range Weather Forecasts (ECMWF) meteorological data and infrared cloud data obtained by the Geostationary Meteorological Satellite (GMS)-5. A case study for the highest CO event shows that it was likely due to vertical transport of pollutants caused by deep cumulus convection along a quasi-stationary frontal zone, which was formed over central China (around the Yangtze River at 30degreesN). In the mean meteorological field during the PEACE-B period, the warm, moist low-level southerlies converged into the frontal zone, sustaining cross-frontal temperature and moisture contrasts. Along the frontal zone, the mean vertical motion was distinctively upward, and a subtropical jet aloft was found to transport uplifted air parcels efficiently into the western Pacific. In this study, criteria to identify deep convection are defined using both the ECMWF and GMS data. The results show that convective activity, which was generally high below the subtropical jet, played an important role in producing updrafts over central China. The convective transport resulted mainly from a limited number of episodes, each of which followed the development of a weak cyclonic disturbance. Back trajectories of air parcels sampled at altitudes between 4 and 13 km on board the aircraft during PEACE-B show that among the air parcels originating from the 800-hPa level or below, 69% were likely to have undergone convective uplifting. In addition to convection, sloping isentropes often observed along the quasi-stationary jet axis yielded persistent slow quasi-adiabatic uplifting of air over the Far East, which was occasionally intensified with a classical warm conveyor belt (WCB) airstream on the passage of migratory cyclonic disturbances. Meteorological conditions during PEACE-B were thus favorable for the uplifting of boundary layer air influenced by anthropogenic emissions over central China. These results are consistent with the relatively high levels of Halon 1211 (CF2ClBr), a good tracer of Chinese anthropogenic emissions, observed in the air parcels that were likely uplifted in the frontal zone.
  • Y Kondo, K Nakamura, G Chen, N Takegawa, M Koike, Y Miyazaki, K Kita, J Crawford, M Ko, DR Blake, S Kawakami, T Shirai, B Liley, Y Wang, T Ogawa
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 109 (D23) 2169-897X 2004/10 [Refereed][Not invited]
     
    Aircraft measurements of ozone (O-3) and its precursors, including NO, CO, H2O, and nonmethane hydrocarbons (NMHCs), were made over the western Pacific in the 20degrees-45degreesN latitude range in January and April-May 2002 during the Pacific Exploration of Asian Continental Emission (PEACE)-A and B campaigns. These measurements have provided data sets that, in combination with Transport and Chemical Evolution over the Pacific (TRACE-P) data taken in March 2001, enable studies of O-3 photochemistry from winter to late spring. A photochemical box model is used to calculate ozone formation (F(O-3)) and destruction (D(O-3)) rates constrained by the observed species concentrations. The values of F(O-3) and D(O-3) are controlled directly by NO, J((OD)-D-1) (O-3 photolysis frequency), H2O, OH, and HO2. Changes in HO2 concentration cause corresponding changes in both F(O-3) and D(O-3), leading to their coupling. Concentrations of these species, which are strongly influenced by photochemistry and transport from the Asian continent, underwent large seasonal variations. In the boundary layer (0-3 km), NO was much higher in January than in April-May, because of stronger winds, lower convective activities, and lower oxidation rates by OH in winter. The net O-3 formation rate, given by P(O-3) = F(O-3)-D(O-3), was largely positive in the boundary layer at 30degrees-45degreesN (1.5-4 ppbv d(-1)) in January, mainly because of high NO and low H2O values. Net O-3 formation continued from January to the end of March, demonstrating that the western Pacific is an important O-3 source region during this season. Net O-3 formation nearly ceased by late April/May because of the decrease in NO and the increase in H2O. In the latitude range of 20degrees-30degreesN, P(O-3) in the boundary layer was positive in January and turned negative by March. The earlier transition was mainly due to lower NO and higher H2O concentrations, combined with weaker transport and higher temperatures than those at 30degrees-45degreesN. The upper troposphere (6-12 km) has been shown to be a region of net O-3 formation throughout most of the year because of high NO and low H2O. The present study illustrates that a decrease in the net O-3 formation rate at 20degrees-45degreesN latitude from winter to late spring is explained systematically by the increases in J((OD)-D-1), H2O, OH, and HO2 (primarily due to increases in temperature and solar radiation) and the decrease in NO ( primarily due to decrease in transport from the Asian continent). Differences in the seasonal variation of O-3 photochemistry observed over the North American continent are interpreted in terms of the differences in factors controlling O-3 formation and destruction.
  • N Takegawa, Y Kondo, M Koike, G Chen, T Machida, T Watai, DR Blake, DG Streets, JH Woo, GR Carmichael, K Kita, Y Miyazaki, T Shirai, JB Liley, T Ogawa
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 109 (D23) 2169-897X 2004/10 [Refereed][Not invited]
     
    [1] The Pacific Exploration of Asian Continental Emission Phase A (PEACE-A) aircraft measurement campaign was conducted over the western Pacific in January 2002. Correlations of carbon monoxide ( CO) with carbon dioxide (CO2) and back trajectories are used to identify plumes strongly affected by Asian continental emissions. DeltaCO/DeltaCO(2) ratios (i.e., linear regression slopes of CO/CO2) in the plumes generally fall within the variability range of the CO/CO2 emission ratios estimated from an emission inventory for east Asia, demonstrating the consistency between the aircraft measurements and the emission characterization. Removal rates of reactive nitrogen (NOx and NOy) for the study region ( altitude < 4 km, 124 degrees - 140 degrees E, 25 degrees - 45 degrees N) are estimated using the correlation with CO2, the photochemical age of the plumes, and the NOx/CO2 emission ratio derived from the emission inventory. The plume age is estimated from the rates of hydrocarbon decay and hydroxyl radical (OH) concentration calculated using a constrained photochemical box model. The average lifetime of NOx is estimated to be 1.2 +/- 0.4 days. Possible processes controlling the NOx lifetime are discussed in conjunction with results from earlier studies. The average lifetime of NOy is estimated to be 1.7 +/- 0.5 days, which is comparable to the NOy lifetime of 1.7 - 1.8 days that has been previously reported for outflow from the United States. This similarity suggests the importance of chemical processing near the source regions in determining the NOy abundance.
  • Y. Kondo, Y. Morino, N. Takegawa, M. Koike, K. Kita, Y. Miyazaki, G. W. Sachse, S. A. Vay, M. A. Avery, F. Flocke, A. J. Weinheimer, F. L. Eisele, M. A. Zondlo, R. J. Weber, H. B. Singh, G. Chen, J. Crawford, D. R. Blake, H. E. Fuelberg, A. D. Clarke, R. W. Talbot, S. T. Sandholm, E. V. Browell, D. G. Streets, B. Liley
    Journal of Geophysical Research D: Atmospheres 109 (15) D15 - S12 0148-0227 2004/08/16 [Refereed][Not invited]
     
    Aircraft measurements of ozone (O3) and its precursors (reactive nitrogen, CO, nonmethane hydrocarbons) were made over the western Pacific during the Transport and Chemical Evolution Over the Pacific (TRACE-P) campaign, which was conducted during February-April 2001. Biomass burning activity was high over Southeast Asia (SEA) during this period (dry season), and convective activity over SEA frequently transported air from the boundary layer to the free troposphere, followed by eastward transport to the sampling region over the western Pacific south of 30°N. This data set allows for systematic investigations of the chemical and physical processes in the outflow from SEA. Methyl chloride (CH3Cl) and CO are chosen as primary and secondary tracers, respectively, to gauge the degree of the impact of emissions of trace species from biomass burning. Biomass burning is found to be a major source of reactive nitrogen (NO x, PAN, HNO3, and nitrate) and O3 in this region from correlations of these species with the tracers. Changes in the abundance of reactive nitrogen during upward transport are quantified from the altitude change of the slopes of the correlations of these species with CO. NOx decreased with altitude due to its oxidation to HNO3. On the other hand, PAN was conserved during transport from the lower to the middle troposphere, consistent with its low water solubility and chemical stability at low temperatures. Large losses of HNO3 and nitrate, which are highly water soluble, occurred in the free troposphere, most likely due to wet removal by precipitation. This has been shown to be the major pathway of NOy loss in the middle troposphere. Increases in the mixing ratios of O3 and its precursors due to biomass burning in SEA are estimated using the tracers. Enhancements of CO and total reactive nitrogen (NOy), which are directly emitted from biomass burning, were largest at 2-4 km. At this altitude the increases in NOy and O3 were 810 parts per trillion by volume (pptv) and 26 parts per billion by volume (ppbv) above their background values of 240 pptv and 31 ppbv, respectively. The slope of the O3-CO correlation in biomass burning plumes was similar to those observed in fire plumes in northern Australia, Africa, and Canada. The O3 production efficiency (OPE) derived from the O3-CO slope and NOx/CO emission ratio (ER) is shown to be positively correlated with the C2H4 /NOx ER, indicating that the C2H4/NO x ER is a critical parameter in determining the OPE. Comparison of the net O3 flux across the western Pacific region and total O3 production due to biomass burning in SEA suggests that about 70% of O3 produced was transported to the western Pacific. Copyright 2004 by the American Geophysical Union.
  • Y Kondo, Y Morino, N Takegawa, M Koike, K Kita, Y Miyazaki, GW Sachse, SA Vay, MA Avery, F Flocke, AJ Weinheimer, FL Eisele, MA Zondlo, RJ Weber, HB Singh, G Chen, J Crawford, DR Blake, HE Fuelberg, AD Clarke, RW Talbot, ST Sandholm, EV Browell, DG Streets, B Liley
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 109 (D15) 2169-897X 2004/07 [Refereed][Not invited]
     
    [1] Aircraft measurements of ozone (O-3) and its precursors ( reactive nitrogen, CO, nonmethane hydrocarbons) were made over the western Pacific during the Transport and Chemical Evolution Over the Pacific (TRACE-P) campaign, which was conducted during February - April 2001. Biomass burning activity was high over Southeast Asia ( SEA) during this period ( dry season), and convective activity over SEA frequently transported air from the boundary layer to the free troposphere, followed by eastward transport to the sampling region over the western Pacific south of 30 degreesN. This data set allows for systematic investigations of the chemical and physical processes in the outflow from SEA. Methyl chloride (CH3Cl) and CO are chosen as primary and secondary tracers, respectively, to gauge the degree of the impact of emissions of trace species from biomass burning. Biomass burning is found to be a major source of reactive nitrogen (NOx, PAN, HNO3, and nitrate) and O-3 in this region from correlations of these species with the tracers. Changes in the abundance of reactive nitrogen during upward transport are quantified from the altitude change of the slopes of the correlations of these species with CO. NOx decreased with altitude due to its oxidation to HNO3. On the other hand, PAN was conserved during transport from the lower to the middle troposphere, consistent with its low water solubility and chemical stability at low temperatures. Large losses of HNO3 and nitrate, which are highly water soluble, occurred in the free troposphere, most likely due to wet removal by precipitation. This has been shown to be the major pathway of NOy loss in the middle troposphere. Increases in the mixing ratios of O-3 and its precursors due to biomass burning in SEA are estimated using the tracers. Enhancements of CO and total reactive nitrogen ( NOy), which are directly emitted from biomass burning, were largest at 2 - 4 km. At this altitude the increases in NOy and O-3 were 810 parts per trillion by volume ( pptv) and 26 parts per billion by volume (ppbv) above their background values of 240 pptv and 31 ppbv, respectively. The slope of the O-3-CO correlation in biomass burning plumes was similar to those observed in fire plumes in northern Australia, Africa, and Canada. The O-3 production efficiency ( OPE) derived from the O-3-CO slope and NOx/CO emission ratio ( ER) is shown to be positively correlated with the C2H4/NOx ER, indicating that the C2H4/NOx ER is a critical parameter in determining the OPE. Comparison of the net O-3 flux across the western Pacific region and total O-3 production due to biomass burning in SEA suggests that about 70% of O-3 produced was transported to the western Pacific.
  • K Nakamura, Y Kondo, G Chen, JH Crawford, N Takegawa, M Koike, K Kita, Y Miyazaki, RE Shetter, BL Lefer, M Avery, J Matsumoto
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 108 (D24) 4752  2169-897X 2003/12 [Refereed][Not invited]
     
    An airborne instrument for in situ measurements of tropospheric nitrogen dioxide (NO2) was developed using the photolytic conversion technique followed by chemiluminescence detection of NO. This instrument was used for the measurements of NO2 on board the NASA P-3B aircraft during the Transport and Chemical Evolution Over the Pacific (TRACE-P) campaign. Comparison in the laboratory indicated less than 10% difference between our NO2 instrument and two independent laser-induced fluorescence instruments in the NO2 range of 30 parts per trillion by volume (pptv) to 50 ppbv. The magnitudes of potential errors in airborne tropospheric NO2 measurements were further assessed using the TRACE-P data set. The systematic errors estimated for the median NO2 mixing ratios, 70 pptv at 0-2 km (30 pptv at 2-8 km), were 19% (39%). The random errors for a 10 s integration time were estimated to be 5-10%, depending on altitude. The observed NO2 mixing ratios were compared to those calculated by a photochemical box model. Overall, the calculated NO2 values correlated very well with those observed (r(2)=0.97), although the calculations were systematically higher than the observations by about 30%, except for the highest flight levels. The calculated/observed NO2 ratio remained nearly constant, having values close to 1.3 at 0-4 km, and decreased with altitude. The difference between the observed and model-calculated values, however, was within the combined uncertainty in the measurement and model calculation. The underlying causes for this difference are to be determined in future studies.
  • M Koike, Y Kondo, K Kita, N Takegawa, Y Masui, Y Miyazaki, MW Ko, AJ Weinheimer, F Flocke, RJ Weber, DC Thornton, GW Sachse, SA Vay, DR Blake, DG Streets, FL Eisele, ST Sandholm, HB Singh, RW Talbot
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 108 (D20) 8789  2169-897X 2003/10 [Refereed][Not invited]
     
    Measurements of gaseous and particulate reactive nitrogen and sulfur species, as well as other chemical species, were made using the P-3B and DC-8 aircraft over the western Pacific during the NASA Transport and Chemical Evolution over the Pacific (TRACE-P) experiment, conducted between February and April 2001. These measurements provide a good opportunity to study the extent to which anthropogenic NOx and SO2 emitted over the East Asian countries remain as NOy and SOx (=SO2 + nssSO(4)(2-)) in the form of gas or fine particles when an air mass is transported into the western Pacific region. In this paper a method to estimate transport efficiencies, epsilon(NOy) and epsilon(SOx), in an air mass that has experienced multiple injection, mixing, and loss processes is described. In this analysis, CO and CO2 are used as passive tracers of transport, and the emission inventories of CO, CO2, NOx, and SO2 over the East Asia region are used. Results from the P-3B presented in this study indicate that 20-40% and 15% of NOx emitted over the northeastern part of China remained as NOy over the western Pacific in the boundary layer (BL) and free troposphere (FT), respectively. In the FT, PAN is found to have been the dominant form of NOy, while only 0.5% of emitted NOx remained as NOx. The transport efficiency of SOx is estimated to have been 25-45% and 15-20% in the BL and FT, respectively. Median values of the nssSO(4)(2-)/SOx ratio are 0.4-0.6 both in the BL and FT, however large variability is found in the FT. These results are generally consistent with those derived using DC-8 data. The results obtained in this study indicate that more than half of NOy and SOx were lost over the continent and that the vertical transport from the BL to FT further reduced their amounts by a factor of 2, likely due to wet removal. Budgets of NOy and SOx were also studied for air masses, which we sampled during TRACE-P and the flux out from the continent in these cases is estimated to be 20% of the emissions. Flux in the BL and FT is found to have a similar contribution.
  • Y Miyazaki, Y Kondo, M Koike, HE Fuelberg, CM Kiley, K Kita, N Takegawa, GW Sachse, F Flocke, AJ Weinheimer, HB Singh, FL Eisele, M Zondlo, RW Talbot, ST Sandholm, MA Avery, DR Blake
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 108 (D20) doi:10.1029/2002JD003248  2169-897X 2003/09 [Refereed][Not invited]
     
    [1] Pathways of synoptic-scale uplifted transport of pollutants from East Asia and their effects on chemical distributions of NOy species are investigated based on a subset of the aircraft data obtained during the NASA Transport and Chemical Evolution over the Pacific (TRACE-P) experiment, conducted in February-April 2001. Meteorological and chemical analyses indicate that 73% of the uplifted transport was associated with warm conveyor belts (WCBs) and convective outflow (COF), which transported air masses strongly impacted by biomass burning over Southeast Asia. The rest (27%) of the uplifted air masses originated over coastal regions of northeast China, where fossil fuel combustion was a dominant source of pollutants. Both WCB associated with a midlatitude cyclone and COF associated with a stationary front over southeast China are examined in detail for the April 4 case. During the TRACE-P period, low NOx(= NO + NO2)/ NOy ratios in the WCB and COF indicate that a significant part of the NOx was oxidized to nitric acid (HNO3) and peroxyacetyl nitrate (PAN) during transport. Low HNO3/NOy ratios in the WCB and COF airstreams indicate that a large amount of HNO3 was removed during transport on timescales within 1-3 days. PAN was found to be the dominant form of NOy in air masses transported by the WCB and COF, likely due to the production of PAN in regions of biomass burning and industrial emissions, as well as due to the rapid removal of HNO3 during transport. For emissions that were transported to the free troposphere by WCBs and COF, about 10-20% of the NOy remained after transport to the free troposphere, and 30% of the NOy surviving in the boundary layer in limited cases. The results indicate that the WCB and COF provide both an efficient sink for HNO(3 a)nd an efficient mechanism for the transport of PAN from the boundary layer to the free troposphere over the western Pacific.
  • N Takegawa, Y Kondo, M Koike, M Ko, K Kita, DR Blake, N Nishi, W Hu, JB Liley, S Kawakami, T Shirai, Y Miyazaki, H Ikeda, J Russel-Smith, T Ogawa
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 108 (D10) 8789  2169-897X 2003/05 [Refereed][Not invited]
     
    [1] The Biomass Burning and Lightning Experiment Phase B (BIBLE-B) aircraft measurement campaign was conducted over the western Pacific and Australia in August and September 1999. In situ aircraft measurements of carbon monoxide (CO), nitric oxide (NO), total reactive nitrogen (NOy), ozone (O-3), nonmethane hydrocarbons (NMHCs), and other species were made during BIBLE-B. Meteorological analysis shows that the trace gases emitted from biomass burning in northern Australia were mostly confined within the planetary boundary layer (below 3 km) by strong subsidence in the free troposphere. Removal processes of NOx (equal to measured NO + calculated NO2) and NOy in biomass burning plumes in the boundary layer are examined on the basis of correlation analysis. The photochemical lifetime of NOx in biomass burning plumes during the daytime is estimated to be 0.1 to 0. 3 days using the correlations of NOx with short-lived NMHCs and hydroxyl radical (OH) concentration calculated from a constrained photochemical model. Correlation of NOy with CO shows that 60% of the NOy molecules originating from biomass burning were removed in the boundary layer within 2-3 days. This result is consistent with dry deposition of nitric acid (HNO3)in the plumes. It is likely that only a small fraction of NOy emitted from biomass burning was exported from the boundary layer to the free troposphere during the BIBLE-B period.
  • N Takegawa, Y Kondo, M Ko, M Koike, K Kita, DR Blake, W Hu, C Scott, S Kawakami, Y Miyazaki, J Russell-Smith, T Ogawa
    GEOPHYSICAL RESEARCH LETTERS 30 (10) 1500  0094-8276 2003/05 [Refereed][Not invited]
     
    [1] In situ aircraft measurements of ozone (O-3) and its precursors were made over northern Australia in August September 1999 during the Biomass Burning and Lightning Experiment Phase B (BIBLE-B). A clear positive correlation of O3 with carbon monoxide ( CO) was found in biomass burning plumes in the boundary layer (<3 km). The Delta O-3/Delta CO ratio ( linear regression slope of O-3-CO correlation) is found to be 0.12 ppbv/ppbv, which is comparable to the ratio of 0.15 ppbv/ppbv observed at 0 4 km over the Amazon and Africa in previous studies. The net flux of O-3 exported from northern Australia during BIBLE-B is estimated to be 0.3 Gmol O-3/day. In the biomass burning region, large enhancements of O-3 were coincident with the locations of biomass burning hot spots, suggesting that major O-3 production occurred near fires ( horizontal scale < 50 km).
  • Y Kondo, N Takegawa, Y Miyazaki, M Ko, M Koike, K Kita, S Kawakami, T Shirai, T Ogawa, DR Blake, B Liley, J Russell-
    INTERNATIONAL JOURNAL OF WILDLAND FIRE 12 (3-4) 271 - 281 1049-8001 2003 [Refereed][Not invited]
     
    In situ aircraft measurements of trace gases and aerosols were made in the boundary layer (BL) and free troposphere ( FT) over Indonesia and Australia during the Biomass Burning and Lightning Experiment (BIBLE)-A and B conducted in August - October 1998 and 1999. Concentrations of ozone (O(3)) and its precursors [CO, reactive nitrogen (NO(x)), non-methane hydrocarbons (NMHCs)] were measured in these campaigns to identify the sources of NO(x) and to estimate the effects of biomass burning and lightning on photochemical production of O(3). Over Indonesia, in-situ production of NO(x) by lightning was found to be a major source of reactive nitrogen in the upper troposphere during BIBLE-A. In some circumstances, increases in reactive nitrogen were often associated with enhancements in CO and NMHCs, suggesting that the sources were biomass burning and fossil fuel combustion, followed by upward transport by cumulus convection. Over Australia the levels of O(3), CO, reactive nitrogen, and NMHCs were elevated throughout the troposphere compared to those observed in the tropical Pacific. However, the mechanisms responsible for the enhanced concentrations in the BL and FT are distinctly different. The emissions from biomass burning that occurred in northern Australia were restricted to the BL because of strong subsidence in the period. In the FT over Australia, elevated concentrations of O(3) and its precursors result from injections of emissions as the air masses travel over Africa, South America, the Indian Ocean, and Indonesia en route to Australia. In all cases, O(3) levels in the biomass burning plumes were enhanced due to photochemical production.
  • Y Kondo, M Koike, K Kita, H Ikeda, N Takegawa, S Kawakami, D Blake, SC Liu, M Ko, Y Miyazaki, H Irie, Y Higashi, B Liley, N Nishi, Y Zhao, T Ogawa
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 108 (D3) 2169-897X 2002/12 [Refereed][Not invited]
     
    In situ aircraft measurements of O-3, CO, total reactive nitrogen (NOy), NO, and non-methane hydrocarbons (NMHCs) were made over the western Pacific Ocean and Australia during the Biomass Burning and Lightning Experiment (BIBLE) A and B conducted in August-October 1998 and 1999. Generally, similar features were seen in the BIBLE A and B data in the latitudinal variations of these species in the troposphere from 35degreesN to 28degreesS at longitudes of 120degrees-150degreesE. The focus of this paper is to describe the characteristics of air masses sampled at 15degreesN-10degreesS (tropical Pacific) and 10degreesS-28degreesS (over Australia). With the exception of occasional enhancements in reactive nitrogen seen over New Guinea associated with lightning activities, the tropical Pacific region is distinguished from the rest of the region by smaller concentrations of these trace species. This can be explained in terms of the absence of surface sources over the ocean, lack of stratospheric intrusion, and the preclusion of midlatitude air and air from the west due to active convection throughout the troposphere. The median O-3, CO, NOy, and NO mixing ratios in tropical air above 4 km were about 15-20 parts per billion by volume (ppbv), 60-75 ppbv, 20-100 parts per trillion by volume (pptv), and 5-40 pptv, respectively. Data obtained from PEM-West A and B conducted in 1991 and 1994 showed similar latitudinal features, although the PEM-West A values were somewhat elevated due to dominating westerly winds in the lower troposphere associated with El Nino. Over Australia, the levels of O-3, CO, NOy, NO, and NMHCs were elevated throughout the troposphere over those observed in the tropical Pacific both in 1998 and 1999. The effect from biomass burning that occurred in northern Australia was limited to within the boundary layer because of strong subsidence in the period. Analyses based on 14-day back trajectories identified free tropospheric air over Australia that originated from Indonesia, the Indian Ocean, Africa, and southern midlatitudes. The levels of O-3, CO, NOy, and NMHCs in these air masses were much higher than those from the tropical Pacific due to their stronger sources from biomass burning and lightning. These values are compared with those obtained in the South Pacific during PEM-Tropics A. Effects of biomass burning and lightning are discussed as possible sources of O-3 and its precursors in these air masses.
  • Y Miyazaki, K Kita, Y Kondo, M Koike, M Ko, W Hu, S Kawakami, DR Blake, T Ogawa
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 108 (D3) doi:10.1029/2001JD000811  2169-897X 2002/11 [Refereed][Not invited]
     
    [1] Aircraft observations of ozone and its precursors (NO, NOy, CO, and nonmethane hydrocarbons) were made near Japan (26degrees-44degreesN) between 21 and 24 April 1998 to investigate the effect of transport and chemistry on the tropospheric ozone over east Asia in spring. The average mixing ratios of ozone and its precursors in the upper troposphere were higher than those observed during February-March 1994. Significantly higher values of CO indicate that the influence of surface sources mediated by convection was large throughout the troposphere during the period. Highly polluted air masses were observed in the upper troposphere at 8-11 km over the Japan Sea on 24 April. These air masses were influenced by cumulus convection associated with a cold front over northeast China about 1 day prior to the observation. However, the majority of observed air masses in the upper troposphere were not directly affected by the recent emissions of the ozone precursors from east Asia. Instead, convection over other regions in the northern midlatitude, followed by long-range transport, affected the abundances of ozone precursors in the upper troposphere. In these air masses, ozone was positively correlated with NOx and C3H8, indicating the effect of photochemical ozone production. The diurnal-average column-integrated rate of ozone production, estimated by a photochemical box model, was larger than the NH average and local stratospheric flux at NH midlatitudes in spring by a factor of 3-20. The net production rates in the majority of the air masses were estimated to be 0.5-4.4 ppbv d(-1) in the upper troposphere. These results indicate the important role photochemistry plays in controlling the upper tropospheric ozone abundance in spring.
  • K Kita, S Kawakami, Y Miyazaki, Y Higashi, Y Kondo, N Nishi, M Koike, DR Blake, T Machida, T Sano, W Hu, M Ko, T Ogawa
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 108 (D3) 2169-897X 2002/11 [Refereed][Not invited]
     
    [1] The Biomass Burning and Lightning Experiment phase A (BIBLE-A) aircraft observation campaign was conducted from 24 September to 10 October 1998, during a La Nina period. During this campaign, distributions of ozone and its precursors (NO, CO, and nonmethane hydrocarbons (NMHCs)) were observed over the tropical Pacific Ocean, Indonesia, and northern Australia. Mixing ratios of ozone and its precursors were very low at altitudes between 0 and 13.5 km over the tropical Pacific Ocean. The mixing ratios of ozone precursors above 8 km over Indonesia were often significantly higher than those over the tropical Pacific Ocean, even though the prevailing easterlies carried the air from the tropical Pacific Ocean to over Indonesia within several days. For example, median NO and CO mixing ratios in the upper troposphere were 12 parts per trillion (pptv) and 72 parts per billion (ppbv) over the tropical Pacific Ocean and were 83 pptv and 85 ppbv over western Indonesia, respectively. Meteorological analyses and high ethene (C2H4) mixing ratios indicate that the increase of the ozone precursors was caused by active convection over Indonesia through upward transport of polluted air, mixing, and lightning all within the few days prior to observation. Sources of ozone precursors are discussed by comparing correlations of some NMHCs and CH3Cl concentrations with CO between the lower and upper troposphere. Biomass burning in Indonesia was nearly inactive during BIBLE-A and was not a dominant source of the ozone precursors, but urban pollution and lightning contributed importantly to their increases. The increase in ozone precursors raised net ozone production rates over western Indonesia in the upper troposphere, as shown by a photochemical model calculation. However, the ozone mixing ratio (similar to20 ppbv) did not increase significantly over Indonesia because photochemical production of ozone did not have sufficient time since the augmentation of ozone precursors. Backward trajectories show that many air masses sampled over the ocean south of Indonesia and over northern Australia passed over western Indonesia 4-9 days prior to being measured. In these air masses the mixing ratios of ozone precursors, except for short-lived species, were similar to those over western Indonesia. In contrast, the ozone mixing ratio was higher by about 10 ppbv than that over Indonesia, indicating that photochemical production of ozone occurred during transport from Indonesia. The average rate of ozone increase (1.8 ppbv/d) during this transport is similar to the net ozone formation rate calculated by the photochemical model. This study shows that active convection over Indonesia carried polluted air upward from the surface and had a discernable influence on the distribution of ozone in the upper troposphere over the Indian Ocean, northern Australia, and the south subtropical Pacific Ocean, combined with NO production by lightning.
  • N. Takegawa, K. Kita, Y. Kondo, Y. Matsumi, D. D. Parrish, J. S. Holloway, M. Koike, Y. Miyazaki, N. Toriyama, S. Kawakami, T. Ogawa
    Journal of Geophysical Research Atmospheres 106 (20) 24237 - 24244 0148-0227 2001/10/27 [Refereed][Not invited]
     
    An airborne instrument for fast-response, high-precision measurement of tropospheric carbon monoxide (CO) was developed using a vacuum ultraviolet (VUV) resonance fluorescence technique. The excitation radiation is obtained by a DC discharge CO resonance lamp combined with an optical filter for the CO fourth positive band emission around 150 nm. The optical filter consists of a VUV monochromator and a crystalline quartz window (< 147-nm cutoff). The crystalline quartz window ensures a sharp discrimination against wavelengths below 135.7 nm that yield a positive interference from water vapor. Laboratory tests showed that the optical system achieved a precision of 1.1 parts per billion by volume (ppbv) at a CO concentration of 100 ppbv for a 1-s integration period, and the flow system provided a response time (1/e time constant) of ∼2 s. The aircraft measurement campaign Biomass Burning and Lightning Experiment-phase B (BIBLE-B) was conducted between August and September 1999 over the western Pacific and Australia. The flight data obtained during this campaign were used to demonstrate the high precision and fast response of the instrument. An intercomparison of the VUV CO measurement and a gas chromatographic CO measurement was conducted during BIBLE-B. Overall, these two independent measurements showed good agreement, within the experimental uncertainties. Copyright 2001 by the American Geophysical Union.
  • N Takegawa, K Kita, Y Kondo, Y Matsumi, DD Parrish, JS Holloway, M Koike, Y Miyazaki, N Toriyama, S Kawakami, T Ogawa
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 106 (D20) 24237 - 24244 2169-897X 2001/10 [Refereed][Not invited]
     
    An airborne instrument for fast-response, high-precision measurement of tropospheric carbon monoxide (CO) was developed using a vacuum ultraviolet (VUV) resonance fluorescence technique. The excitation radiation is obtained by a DC discharge CO resonance lamp combined with an optical filter for the CO fourth positive band emission around 150 run. The optical filter consists of a VUV monochromator and a crystalline quartz window (< 147-nm cutoff). The crystalline quartz window ensures a sharp: discrimination against wavelengths below 135.7 nm that yield a positive interference from water vapor. Laboratory tests showed that the optical system achieved a precision of 1.1 parts per billion by volume (ppbv) at a CO concentration of 100 ppbv for a 1-s integration period, and the flow system provided a response time (Ile time constant) of similar to2 s. The aircraft measurement campaign Biomass Burning and Lightning Experiment-phase B (BIBLE-B) was conducted between August and September 1999 over the western Pacific and Australia. The flight data obtained during this campaign were used to demonstrate the high precision and fast response of the instrument. An intercomparison of the VUV CO measurement and a gas chromatographic CO measurement was conducted during BIBLE-B. Overall, these two independent measurements showed good agreement, within the experimental uncertainties.
  • Increase of ozone and ozone precursor gases in the upper troposphere over the Indonesian-Northern Australian region observed during BIBLE-A aircraft observation campaign
    K. Kita, Y. Miyazaki, Y. Higashi, S. Kawakami, T. Sano, M. Takeda, N. Nishi, Y. Kondo, M. Koike, D. R. Blake, N. Blake, B. Liley, T. Machida, W. Hu, M. Ko, J. Rodriguez, T. Ogawa
    Proceedings of Quadrennial Ozone Symposium Sapporo 2000 479-480  2000 [Not refereed][Not invited]
  • High concentrations of ozone precursors observed in the upper troposphere over East Asia by aircraft measurements in April 1998
    Y. Miyazaki, K. Kita, Y. Kondo, S. Kawakami, T. Machida, D. Blake, N. Nishi, T. Ogawa
    Proceedings of Quadrennial Ozone Symposium Sapporo 2000 553-554  2000 [Not refereed][Not invited]
  • Tropospheric ozone over Pacific and Indonesian Region: Relation with ENSO activity and a preliminary report on BIBLE aircraft campaign
    K. Kita, M. Fujiwara, Y. Miyazaki, S. Kawakami, T. Ogawa, N. Komala, S. Saraspriya, Y. Kondo, M. Koike, T. Machida, B. Liley, D. Blake, M. Watanabe, N. Nishi
    Proceedings of International symposium on tropospheric ozone in East Asia and its potential impacts on vegetation 45-46  1998 [Not refereed][Not invited]

Books etc

  • 低温科学便覧 (北海道大学低温科学研究所編)
    宮﨑 雄三 (Contributor第10章 有機エアロゾル)
    丸善出版 2015

MISC

Awards & Honors

  • 2017 日本地球惑星科学連合 (JpGU) 第2回地球惑星科学振興西田賞
     「大気有機エアロゾルの起源に関する観測的研究」 
    受賞者: 宮﨑 雄三
  • 2016 日本気象学会 2016年度 正野賞
     
    受賞者: 宮﨑 雄三
  • 2011 日本大気化学会 第7回（2011年度）奨励賞
  • 2009 日本気象学会 2009年度 山本・正野論文賞

Research Grants & Projects

  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2023/04 -2027/03 
    Author : 持田 陸宏, 佐藤 圭, 石塚 紳之介, 木村 勇気, 松井 仁志, 宮崎 雄三, 大畑 祥
  • 日本学術振興会：科学研究費助成事業
    Date (from‐to) : 2022/04 -2026/03 
    Author : 山下 洋平, 宮崎 雄三, 入野 智久
  • 亜寒帯海域での大気有機態窒素エアロゾル生成量・組成変動を支配する微生物要因の解明
    科研費補助金 基盤研究(B)
    Date (from‐to) : 2023/04 -2026/03 
    Author : 宮﨑 雄三
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2020/04 -2024/03 
    Author : 能田 淳, 露口 一成, 御手洗 聡, 森本 耕三, 宮崎 雄三, 牧 輝弥
     
    本研究は、地域ごとの大気環境中のPM2.5の化学的特性及び肺非結核抗酸菌症（肺NTM症）の90%を占めるMAC菌の特異性を把握することと、これら大気環境中の化学成分とMAC菌との相互作用を検証することを目的としている。大気を介したMAC菌感染症の越境の可能性を検証するため、地上付近数十メートルでの測定を全国5拠点（北海道札幌市、東京都清瀬市、石川県珠洲市、大阪府堺市、福岡県福岡市）にて進めている。頻度としては、季節変動の把握を目的として、年4回のサンプリングを季節ごとで進めている。さらに、高高度での拡散条件の把握を行うために、ヘリコプター、航空機などの活用で、隣国などから越境することの可能性も視野に入れつつ観測を進めている。高高度測定については、大阪府、石川県付近など限られた地点での測定ではあるが、地上でのデータとの比較を目指して、できるだけ同時期に測定することを目指す。これらの測定結果で得られたデータを基に、大気中のバイオエアロゾルの挙動を擬似的に検証できる擬似大気チャンバーを用いて、大気中細菌などのバイオエアロゾル活性保持メカニズムの把握、検証を行う。これらの知識構築にて、肺NTM症などの感染が起こりやすい状況をより明確化し、感染症に対応できる生活環境の整備、又は状況の把握か取り組む予防的な対応にて疾病問題の低減化を目ざす。環境因子と関連した感染症対策は知識が不十分であるため、本研究には大きな意義がありこれらの対応を進めていくことは感染症対策として健康維持に向けた重要な取り組みである。
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2021/07 -2023/03 
    Author : 宮﨑 雄三
     
    本研究は、海水中で微生物が窒素分子を（栄養塩として利用可能な）反応性窒素へと変換するプロセスである窒素固定に着目し、海洋表層の窒素固定生物が大気反応性窒素の有意な放出源となり得るかを明らかにすることを目的としている。今年度は、人工海水（培地）を用いた窒素固定生物の培養-大気捕集システムの構築と実験条件の最適化を行った。人工海水での窒素固定生物の培養と大気捕集が可能な測定システムを恒温槽内に製作し、大気の吸引による培養容器（水槽）内の圧力変化が細胞増殖に与える影響や容器への負荷を調べた。培養容器約30Lの材質は、光合成のための光を照射するため透明かつ強度が大きく、測定への有機物の干渉がないアクリル製を予備実験により選定した。 この実験システムを使用し、窒素固定生物の中でトリコデスミウムを用いた室内培養-大気捕集実験を約２カ月間行った。恒温槽内に設置した人工海水中でトリコデスミウムを培養し、インパクタを用いて24時間毎の大気捕集を行った。インパクタにより粒子相と気相（酸性、アルカリ性）の反応性窒素（アンモニア/アンモニウム塩、有機態窒素、硝酸/硝酸塩等）成分を捕集・測定した。人工海水試料は24時間毎に採取し、溶存態窒素や溶存有機炭素濃度、及びクロロフィルa濃度を計算するための細胞内蛍光強度など微生物指標を測定した。約2か月間の培養期間において、トリコデスミウムの増殖期、減衰期を捉えることに成功し、特にアンモニアの大気放出が衰退期において顕著であることが観測された。同時測定したバクテリアの数も減衰期に増加していたことから、トリコデスミウム増殖に伴う滲出物である溶存窒素、溶存態有機炭素の分解が進み、揮発性の高いアンモニア/アンモニウム塩として大気中へ放出が増大したことが示唆された。同様の大気濃度増大は塩基性の有機態窒素（気相）でも観測された。
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2019/04 -2022/03 
    Author : Mochida Michihiro
     
    In this study, the relationships of the hygroscopicity of organic components in atmospheric aerosol samples with the chemical structures and sources were investigated. For urban aerosols, the mass spectral analysis of the extracts from aerosol samples showed the contributions of organics associated with their sources and chemical structure. Further, the relationships of the hygroscopicity of humic-like substances with the oxygen-to-carbon ratios and sources were obtained. For forest aerosols, the atmospheric concentrations of organic fractions were determined based on mass spectral analysis. Based on the hygroscopic growth measurements for particles such as those composed of the mixtures of humic-like substances and ammonium sulfate, results for the assessment of the additivity of hygroscopicity were also obtained.
  • 海洋大気の有機態窒素エアロゾル：生成量を制御する海洋微生物活動の支配要因は何か？
    科研費補助金 基盤研究(B)
    Date (from‐to) : 2019/04 -2022/03 
    Author : 宮﨑 雄三
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2018/11 -2021/03 
    Author : 宮崎 雄三, XU YU
     
    本年度は昨年度から引き続き大気エアロゾル中のアミノ酸について、実大気中での代表的な反応過程であるオゾン酸化反応を受けた際の同位体分別効果を調べ、起源トレーサーとしての有用性を検証した。同位体比既知の遊離態アミノ酸標準物質、タンパク質のモデル物質としてのウシ血清アルブミンを添加した石英繊維フィルター、および森林観測サイトで採取した大気エアロゾルフィルター試料(TSP)をそれぞれ大気オゾンに曝露した。これにより、オゾン曝露の前後でアミノ酸の窒素、炭素の安定同位体比が有意に変化するかどうか、すなわちエアロゾル中のアミノ酸がオゾンに伴う反応を受けることによる同位体分別効果の影響を調べた。測定には前年度に確立した、石英繊維フィルターからの溶媒抽出、加水分解や誘導体化等のプロセスの後、ガスクロマトグラフ-質量分析計およびガスクロマトグラフ-同位体比質量分析計に導入し、化合物の質量および安定同位体比を測定する手法を用いた。 その結果、主要な化合物を含め、ほとんどのアミノ酸化合物の窒素・炭素の安定同位体比について、オゾン曝露の前後で有意な変化は見られず、オゾンに関連する反応による同位体分別は起きていないことが確認できた。植生内で同位体分別が起きないとされる特定のアミノ酸化合物についての過去の文献と本研究による実験結果から、大気でのオゾン酸化反応を経ても、特にグリシンの安定同位体比などが大気中の生物起源トレーサーとして有用であることが初めて示唆された。
  • 植生由来テルペン類から生成する有機態窒素エアロゾルの起源と生成メカニズムの解明
    科研費補助金 基盤研究(B)
    Date (from‐to) : 2016/04 -2019/03 
    Author : 宮﨑 雄三
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2016/04 -2018/03 
    Author : Koike Takayoshi
     
    Ground-level Ozone (O3) decreased defense leaf capacity because of suppression of photosynthesis. We found severe grazing damages of leaf beetle on a crown of White birch at elevated O3. Contrary to this, choice and non-choice style of feeding experiments showed that leaves exposed to elevated O3 were preferred by leaf beetles because of lower defensive chemicals production. To clarify this phenomenon, we suggested possibility of BVOC (Biogenic Volatile Organic Compounds) as signal chemicals for insects to locate their host plants. BVOCs were roughly sorted into two groups: one was monoterpene (MT), the other was sesquiterpene (SQT). MT and SQT had no significant difference in the basic-emission rate regardless of O3 exposure. Therefore, BVOC emission in itself did not work as a factor of changing grazing activity of leaf beetles although the brand ratio of BVOC should be considered. At high O3, we should study BVOC dynamics through reaction with O3 after emitted in the atmosphere.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2014/04 -2017/03 
    Author : Fujiyoshi Yasushi
     
    Simultaneous ground and in situ observations confirmed the consistent variation of many physical properties in the atmosphere. We also found that strong turbulence near the top of atmospheric boundary layer occurred only in the very narrow region adjacent to small cumulus clouds. We also investigated the spatial and temporal variability of the physical and optical properties of aerosols. We developed a new algorithm to estimate the vertical profiles of the aerosol physical and optical properties. Furthermore, the solar heating rate was estimated from the retrievals, which were directly validated by in situ data collected by a glider. The comparison of the retrieved extinction coefficient with that estimated from in situ measurements showed that our algorithm has a bias error due to the optimization of aerosol parameters to the optical thickness measured by the sky radiometer.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2014/04 -2017/03 
    Author : Mochida Michihiro, DENG Yange, OGAWA Shuhei, KAGAMI Sara, YAI Hikari, KAWANA Kaori, KUBODERA Ryo, TACHIBANA Eri
     
    Field observations of the hygroscopicity and optical properties of atmospheric aerosol were conducted in a forest area of the Kii Peninsula. Hygroscopicity parameters of organic aerosol and biogenic secondary organic aerosol were calculated based on measurements of cloud condensation nuclei. The contributions of organic aerosol and biogenic secondary organic aerosol to the number concentrations of cloud condensation nuclei were assessed. Further, the coatings of black carbon particles were analyzed based on light absorption measurements of the aerosol with and without heating. The hygroscopic growth factors of aerosol particles, the concentrations of tracer species of biogenic secondary organic aerosol, and sky-radiometer data were also obtained. Results and data from this study are expected to be the basis for further characterization of forest aerosols.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2012/05 -2017/03 
    Author : KAWAMURA Kimitaka
     
    In this project, we studied chemical compositions of atmospheric aerosols from East Asia and its outflow regions in the western North Pacific at levels of carbon, nitrogen, organic molecules including carboxylic acids, isotopes and inorganic ions. We found a decline of sulfate concentrations after 2006 due to the sulfur emission control in China, but organic aerosols showed a continuous increase from 2001 to 2013. This increase of organics is largely involved with the emissions of biomass burning of agriculture wastes such as wheat straw in China and other Asian countries. Those trends are consistent with an increase in the biomass-burning tracers such as levoglucosan in the marine aerosols. Hygroscopic properties of aerosol particles were measured for remote marine aerosols. We found that growth factors of marine aerosols are decreased when Asian dusts (Kosa) are transported over the ocean due to the formation of water-insoluble calcium oxalate in spring.
  • 含窒素有機物組成と同位体比測定による有機態窒素エアロゾルの起源の解明
    科研費補助金 基盤研究(B)
    Date (from‐to) : 2013/04 -2016/03 
    Author : 宮﨑 雄三
  • 海洋微生物に由来する大気微粒子ゲル状有機物に含まれるペプチド検出の試み
    科研費補助金 挑戦的萌芽研究
    Date (from‐to) : 2013 -2014 
    Author : 宮﨑 雄三
  • 複合トレーサーを用いた森林土壌への窒素負荷に伴う大気エアロゾル生成への影響の解明
    Date (from‐to) : 2012 -2013 
    Author : 宮﨑 雄三
  • 森林生態系でのCO2固定に対する炭素性微小粒子生成への応答と制御要因の解明
    Date (from‐to) : 2011 -2012 
    Author : 宮﨑 雄三
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2007 -2011 
    Author : KONDO Yutaka, KOIKE Makoto, TAKEKAWA Nobuyuki, TAKEMURA Toshihiko, MIYAZAKI Yuzo
     
    We have developed a black carbon(BC) instrument. Using the BC instrument, aircraft campaigns have been conducted over the western Pacific and the Arctic. We measured various microphysical properties of BC aerosol(e. g., mass concentration, size distribution, mixing state) and showed spatial and temporal distribution, large-scale transport, transformation, and removal processes of BC. We also developed global and regional models that can represent the detailed BC microphysical properties. Model calculations were validated by measurements. Using these models, impact of BC on the Earth's climate has been evaluated quantitatively.
  • 北方森林生態系における植生起源有機エアロゾル生成の観測研究
    Date (from‐to) : 2010 -2010 
    Author : 宮﨑 雄三
  • 日本学術振興会：科学研究費助成事業
    Date (from‐to) : 2009 -2010 
    Author : 河村 公隆, 宮崎 雄三
     
    夏季の西部北太平洋において白鳳丸航海(KH08-02)で採取した降水・霧水試料中に低分子有機酸を測定した。測定には、河村らが開発したフィナシルエステル・GC法(Kawamura et al.,1985)の改良版を用いた。試料を、0.1M KOH水溶液にてpH=8.5に調製したのち、ロータリーエバポレーターを用いて濃縮する。濃縮液を陽イオン交換樹脂に通すことによりすべての有機酸をRCOO^-K^+の化学形にする。次に、溶離液を濃縮・乾燥後、誘導体試薬(α,p-ジブロモアセトフェノン)と触媒(クラウンエーテル:dicyclohexyl-18-crown)を加え、アセトニトリル溶媒中で80℃,2時間反応させ、カルボン酸をp-ブロモフィナシルエステルに誘導体化した。有機酸エステルをシリカゲルカラムにより精製した後、ヒドロキシ有機酸のOH基をBSTFAによりTMS化した。札幌および西部北太平洋で採取した試料から分離した有機酸エステルをキャピラリーGCにて測定した結果、C_1-C_<10>直鎖、側鎖および芳香族の有機酸を検出した。更に、乳酸、グリコール酸(ヒドロキシ有機酸)を検出し、それぞれを定量した。また、GC/MSを用いて化合物の同定を行った。 西部北太平洋上の降水・霧水中において初めて低分子モノカルボン酸(C_1-C_7、乳酸、グリコール酸、3-ヒドロキシブタン酸)を検出した。降水中(4試料)のギ酸(C1)の濃度は4-725ng/g、酢酸(C2)では30-238ng/g、プロピオン酸(C3)では12-12.5ng/g、ブタン酸(C4)では0.1-5.1ng/g、イソブタン酸(iC4)では0.1-2.7ng/g,Valeic acid(C5)では0.0-1.9ng/g,Isovaleic acid(iC5)では0.0-0.9ng/g,Caproic acid(C6)では0.0-5.3ng/g,乳酸では0-153ng/g,Glycolic acidでは0-32ng/g,3-Hydroxybutanoic acidでは0.1-13ng/gであった。ギ酸・酢酸の濃度は、西部北太平洋で採取した降水中(MROO-K02,2000)のシュウ酸濃度よりも高い傾向にあることが明らかとなり、低分子モノカルボン酸は重要な有機物であることがわかった。一方、霧水試料(n=9)についても測定した結果、ギ酸・酢酸が優位であることがわかった。濃度は、ギ酸で63-360ng/g,酢酸で35-303ng/gであり、雨に比べて著しく高いわけではなかった。また、ヒドロキシカルボン酸も検出された。一つの試料中で乳酸の濃度はギ酸・酢酸よりも高かった。 現在、乳酸の吸湿特性(Growth factor)を測定するため、H-TDMAの調整をしている。
  • 大気中における含窒素有機エアロゾルの化学的挙動の解明
    Date (from‐to) : 2009 -2010 
    Author : 宮﨑 雄三
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2007 -2010 
    Author : KAWAMURA Kimitaka, MOCHIDA Michihiro, MIYAZAKI Yuzo, SEKI Osamu
     
    Atmospheric aerosols, collected from China, Korea, Mongolia, India and Japan as well as coastal and remote islands, have been studied for organic chemical compositions. The aerosols from Manshan, 40 km north of Beijing, showed higher concentrations of dicarboxylic acids such as oxalic acid than those from Beijing, suggesting a secondary (photochemical) production of water-soluble organic acids during atmospheric transport. Indian aerosols from New Delhi showed very high concentrations of low molecular weight diacids. Aerosols from Ulaanbaatar were studied for the hygroscopicity, indicating that the growth factor (Gf=1.22) is close to that of biomass burning aerosols.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2007 -2008 
    Author : TAKEGAWA Nobuyuki, KONDO Yutaka, KOIKE Makoto, MIYAZAKI Yuzo
     
    エアロゾル質量分析計(AMS)により得られたアジアの大都市(東京、広州、北京)におけるデータの解析とそれに関連する実験を行った。AMS の質量スペクトルや粒径分布から有機エアロゾルに関する多くの情報を引き出す方法を考案し、これに基づいてアジアの無機・有機エアロゾルの生成・消滅過程の研究を行った。夏季の北京において無機・有機エアロゾルが領域スケールで多量に生成され、それらが低気圧の通過に伴って広域へ輸送されていることが明らかになった。
  • 大気中における水溶性フミン状有機エアロゾルの高速自動測定法の開発
    Date (from‐to) : 2007 -2008 
    Author : 宮﨑 雄三
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2006 -2007 
    Author : KOIKE Makoto, TAKEGAWA Nobuyki, MIYAZAKI Yuzo, KITA Kazuyuki
     
    Recent rapid growth of industrial activities in East Asia has been causing large increase in aerosols in this area. Atmospheric aerosols modify the radiation budget through scattering and absorption. Because black carbon (BC) aerosols (e.g., soot) efficiently absorb the solar radiation, they have been recognized one of the most important aerosol compounds the solar radiation, they have been recognized one of the mot important aerosol compounds for climate change. In the physical year of 2006, measurements of BC mass concentrations, size distribution, and mixing sate were in the Beijing region and Peal River Delta (PRD) region in China with Peking University Research Groups and some other international research groups. Aerosol chemical composition and some other parameters were also simultaneously measured. In the physical year of 2007, these data were precisely analyzed and interpreted from the viewpoint of emission sources, chemical production, transport processes, and removal processes using three-dimensional chemistry transport model. Observations show that BC concentrations in Beijing have a clear diurnal variation with a maximum during night. This feature was well reproduced by model calculations through diurnal variations, such as that in the boundary layer height. Although large day-to-day variations were found for secondary aerosols, such as inorganic aerosols, they were small for BC. Model calculations showed that BC concentrations were generally controlled by BC emissions within 100 km around Beijing within previous 24 hours. On the centrally, emissions as far as 500 km within previous 3 days were found to affect concentrations of secondary aerosols, such as sulfate through accumulations under stable synoptic-scale meteorological conditions.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2005 -2006 
    Author : TAKEGAWA Nobuyuki, KONDO Yutaka, KOMAZAKI Yuichi, KOIKE Makoto, MIYAZAKI Yuzo
     
    1. Improvement of the accuracy of the Aerosol Mass Spectrometer (AMS) The particle collection efficiency (CE) of the AMS depends on relative humidity (RH) in sample air. The temperature of the AMS inlet manifold was maintained at > 10℃ above the ambient dew point to dry particles in the sample air (RH in the inlet < 53%). Assuming CE = 0.5 for the AMS, the mass concentrations of inorganic species (nitrate, sulfate, chloride, and ammonium) measured by the AMS agree with those measured by an Ion Chromatography analyzer (PILS-IC) to within 〜20%. 2. Analysis of the mass spectra of selected organic compounds We have evaluated the contribution of selected low molecular weight dicarboxylic acids (diacids) to the m/z 44 signal of the AMS mass spectrum. We used ambient measurement data obtained in Tokyo and laboratory experiment data obtained using authentic standards of the selected organic acids. We have reported for the first time that the selected organic acids could account for 14% of the observed m/z 44 signal on average during the measurement period. 3. Investigation of the seasonal and diurnal variations of anthropogenic organic aerosol in Tokyo In situ measurements of trace gases and aerosols were conducted at an urban site in Tokyo. Organic aerosol (OA) is classified into primary organic aerosol (POA) and secondary organic aerosol (SOA) using correlation with carbon monoxide (CO). We have found that POA does not exhibit a distinct diurnal variation for the summer, fall, and winter periods, while SOA shows a clear diurnal pattern. We have also found that the OA concentrations can be significantly enhanced within 〜0.5 days under conditions of high photochemical activity.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2005 -2006 
    Author : KONDO Yutaka, TAKEGAWA Nobuyuki, MIYAZAKI Yuzo, KOIKE Makoto
     
    Cloud condensation nuclei (CCN) activity is determined by aerosol diameter, fraction of water soluble components, and surface tension. We quantified CCN activities as a function of these parameters and related them with cloud formation processes. A)Controlling factors of CCN activities of aerosol in urban air We measured chemical composition, mixing states, and CCN activity of aerosol in Tokyo using an aerosol mass spectrometer, black carbon (BC) instruments, and a CCN counter. We found that CCN activity of thickly coated BC is controlled by the chemical composition of water soluble compounds. The CCN activity of thinly coated BC is controlled by the thickness of the coating. B)Measurements of aerosol-cloud interaction We conducted aircraft measurements of aerosol and cloud particles inside and outside of clouds located at 1-2 km near Japan in spring. We showed that thickly coated BC particles were taken up into clouds efficiently, consistent with the ground based measurements. This also shows that BC can be a good tracer to quantitatively study aerosol-cloud interaction. C)Time constant of CCN formation We showed that CCN activity of aerosol transported from the Asian continent within a few days is controlled mainly by the fraction of water soluble components from the data obtained in Jeju Island, Korea. Decrease in the surface tension of organic aerosol is also estimated to is contribute to the CCN activity. The CCN activity of various types of aerosol was measured also near Beijing. The observed CCN activity is consistent with the understandings obtained in Tokyo and Jeju Is. D)Calibration of the cloud probe and its aerodynamical characteristics Light scattering cloud probe was calibrated using standard particles with high precision. We made aerodynamical calculations of airflows around the probe mounted on the aircraft and found high collection efficiency of cloud droplets. E)We calculated size distribution of cloud droplets predicted from various CCN concentrations using a trajectory model. Sensitivity of CCN-cloud interaction was estimated by the numerical experiments.
  • 水溶性有機エアロゾルの高感度実時間連続測定法の開発
    Date (from‐to) : 2005 -2006 
    Author : 宮﨑 雄三
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2004 -2005 
    Author : KOMAZAKI Yuichi, KONDO Yutaka, TAKEGAWA Nobuyuki, KOIKE Makoto
     
    EC comprises a significant portion of nano-particles, which are harmful to human health. EC has also been identified as making important contributions to the radiative heating of the atmosphere. Mass concentrations of EC in fine mode and CO were measured in Tokyo. EC were measured using a semi-continuous thermal-optical analyzer. The mass concentrations of non-volatile fine-particle measured by the calibrated SMPS combined with a heated inlet agreed with the independent EC measurements, demonstrating that the mass concentrations of non-volatile particle well those for EC. EC mass concentration was in volume equivalent diameters between 50-200 nm, peaking at around 130 nm. The correlation of EC and CO was generally compact throughout the measurement period. The slope of the EC-CO correlation (ΔEC/ΔCO) is therefore a useful parameter in validating EC emission inventories. The EC concentration and ΔEC/ΔCO showed distinct diurnal variation. On weekdays, EC and ΔEC/ΔCO reached maximum values, respectively, in the early morning, when the traffic density of heavy-duty trucks with diesel engines was highest. In addition, these values were lower by a factor of 2 on Sundays. The heavy truck traffic showed similar diurnal and weekday/weekend variations, indicating that exhaust from diesel engines is an important source of EC. Monthly mean ΔEC/ΔCO showed a seasonal variation, reaching broad maximum values in spring-autumn and reaching minimum values in midwinter. More stringent regulation of emissions of particles from diesel cars started in the Tokyo metropolitan area in October 2003. The ΔEC/ΔCO values did not change significantly (10%) after one year from the start of the new regulations, when the temperature dependence is taken into account. This indicates that the regulation of particle emissions in the Tokyo Metropolitan Area was not effective in reducing the EC concentrations after one year.
  • 日本学術振興会：科学研究費助成事業
    Date (from‐to) : 2004 -2005 
    Author : 近藤 豊, 小池 真, 宮崎 雄三
     
    元素状炭素(EC、あるいはブラックカーボン)は、高濃度になる地域では人体に悪影響を及ぼす。さらに太陽光の吸収が強いため大気の放射収支にも重要な影響を与える。本研究では都市域においてECの長期観測を行い、COをトレーサーとして用いることでECの排出源と大気中での挙動(季節変化、日変化、粒径分布)やそれらを支配する要因を明らかにした。このために高い時間分解能(1時間)と測定精度を持つ熱・光学方式によるEC計、及び大気導入部を加熱したScanning Mobility Particle Sizer(SMPS)(不揮発性粒子を選択的に測定)を用いて観測を行った。観測は代表的なメガシティーである東京都市域において通年(2003年5月ー2005年2月)で行ってきた。 SMPSにより測定された不揮発性粒子の質量濃度とEC分析装置によるEC質量濃度は10%の範囲内で良く一致し、不揮発性粒子の質量濃度はEC質量濃度を代表することが示された。また、EC質量濃度の大部分は体積等価粒径130nm付近にピークを持つことがわかった。ECとCOは良い相関(R^2=0.62)を示し、類似の排出源を持つことが示唆された。観測全期間のEC、COの中央値はそれぞれ1.8±1.8μgm^<-3>、368±274ppbvであった。また、ディーゼル車からの排出が卓越する早朝のΔEC/ΔCO比は7.2±2.6×10^<-3>ngm^<-3>/ppbvと変動は小さい。ΔEC1ΔCO比は気温の季節変化に対応し春-秋に最大値を示した。東京都におけるEC排出の規制開始(2003年10月)後1年で東京都での粒子排出規制後1年でΔEC/ΔCO比に自然変動(10%)以上の変化は見られなかった。
  • 大気中における極性有機エアロゾルの挙動・起源の解明
    Date (from‐to) : 2004
  • 海洋大気の有機態窒素エアロゾル：生成量を制御する海洋微生物活動の支配要因は何か？
    科研費補助金 基盤研究(B)
    Author : 宮﨑 雄三

Educational Activities

Teaching Experience

  • Fundamental Course in Marine and Atmospheric Chemistry
    開講年度 : 2021
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : 大気化学、海洋化学 Atmospheric Chemistry, Marine Chemistry
  • Fundamental Course in Biogeochemistry
    開講年度 : 2021
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : 海洋化学、大気化学、生物地球化学、物質循環、地球環境問題 Marine Chemistry, Atmospheric Chemistry, Biogeochemistry, Material Cycling, Global Environmental Issues
  • Environment and People
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 全学教育
    キーワード : 大気、海洋、生態系、気候変化、地球環境問題、地球温暖化、成層圏オゾン層破壊、大気汚染

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