Researcher Profile and Settings

Affiliation

• Research Faculty of Agriculture　Fundamental AgriScience Research　Bioresource and Environmental Engineering

Job Title

• Professor

Degree

• Dr. Eng.（2010/03 Saitama University）

URL

https://kaken.nii.ac.jp/d/r/30581946.ja.html

Researcher ID

• E-6755-2012

J-Global ID

• 201601017423659509

Research Interests

• 土壌ガス   放射性Cs   多孔質体   根圏土壌   X線CT   物質移動   温度環境   物質輸送係数   環境リスク   廃棄物処分場覆土   透水   マルチフェーズ輸送   圧密   マイクロ・ナノバブル   

Research Areas

• Environmental science/Agricultural science / Rural environmental engineering and planning
• Social infrastructure (civil Engineering, architecture, disaster prevention) / Geotechnical engineering

Academic & Professional Experience

• 2023/04 - Today 北海道大学 大学院農学研究院 教授
• 2016/10 - 2023/03 東京大学大学院農学生命科学研究科 准教授
• 2013 - 2016/09 The University of Tokyo Graduate School of Agricultural and Life Sciences
• 2010/04 - 2013/09 埼玉大学大学院理工学研究科 助教

Education

• 2007/04 - 2010/03  Saitama University  Graduate School of Science and Engineering
• 2004/04 - 2007/03  The University of Tokyo  Graduate School of Agricultural and Life Sciences  Biological and Environmental Engineering
• 2000/04 - 2004/03  Hokkaido University  Faculty of Agriculture  Department of Agricultural Engineering

Association Memberships

• 農業農村工学会   アメリカ土壌科学会   土壌肥料学会   混相流学会   地盤工学会   土壌物理学会   

Research Activities

Published Papers

• Impact of Water Management on Methane Emission Dynamics in Sri Lankan Paddy Ecosystems

  M. M.Tharindi Lakshani, T. K.K.Chamindu Deepagoda, Yuan Li, H. F.E. Hansen, Bo Elberling, Sarath P. Nissanka, Dassanayake M.J.B. Senanayake, Shoichiro Hamamoto, G. L.Sivakumar Babu, Hoysala N. Chanakya, Parameswaran T. G, Pandit G. Arunkumar, Bjoern Ole Sander, Timothy J. Clough, Kathleen Smits

  Water (Switzerland) 15 (21) 2023/11 

  Paddy ecosystems constitute a dominant source of greenhouse gases, particularly of methane (CH4), due to the continuous flooding (CF) practiced under conventional paddy cultivation. A new management method, namely alternative wetting and draining (AWD) (i.e., flooding whenever surface water levels decline to 15 cm below the soil surface), is an emerging practice developed to mitigate CH4 emissions while providing an optimal solution for freshwater scarcity. Despite extensive paddy cultivation in Sri Lanka, no systematic research study has been conducted to investigate CH4 emissions under different water management practices. Thus, field experiments were conducted in Sri Lanka to investigate the feedback of controlled water management on seasonal and diel variation of CH4 emission, water consumption, and crop productivity. Adopting the same rice variety, two water management methods, continuous flooding (CF) and alternative wetting and draining (AWD), were compared with plants (W/P) and without plants (N/P) present. The emission of CH4 was measured using the static closed chamber method. The results show a 32% reduction in cumulative CH4 emission, on average, under AWD when compared to CF. The yield under the AWD was slightly higher than that of CF. Although it was not statistically significant (p > 0.05) there was not any reduction in yield in AWD than in CF. The total water saving under AWD ranged between 27–35% when compared to CF. Thus, the results support (without considering the effect of nitrous oxide) AWD as a promising method for mitigating CH4 emissions while preserving freshwater and maintaining grain yield in paddy systems.
• Base flow separation for soil erosion simulation in a granitic forested headwater catchment using a process-based model, GeoWEPP

  Takuhei Yamasaki, Shoichiro Hamamoto, Taku Nishimura

  International Journal of Sediment Research 38 (4) 494 - 502 1001-6279 2023/08 [Refereed]
   

  Distributed erosion models, which simulate the physical processes of water flow and soil erosion, are effective for predicting soil erosion in forested catchments. Although subsurface flow through multiple pathways is dominant for runoff generation in forested headwater catchments, the process-based erosion model, Geo-spatial interface for Water Erosion Prediction Project (GeoWEPP), does not have an adequate subsurface component for the simulation of hillslope water flow. In the current study, the quick flow related to soil erosion during rainfall events is separated from the total hydrograph using base flow separation for GeoWEPP to use direct runoff to predict sediment discharge from a granitic-forested catchment in Japan. Water runoff and sediment discharge also are simulated using the conventional method that reproduces the total hydrograph, and the accuracy of the calculation and estimated erodibility parameters are evaluated. The proposed procedure reproduced the quick-flow runoff during rainfall and the cumulative sediment discharge from the catchment. Simultaneously, the proposed procedure overestimates water runoff during extreme weather events, such as typhoons. The estimated erodibility parameters for the hillslope soil were comparable to those of the surface soil in Japan using both the proposed procedure and the conventional one. Conversely, the channel erodibility obtained from the proposed procedure matched the observed sediment characteristics in the granitic forested catchment. The proposed procedure is a promising method to predict sediment discharge from forested catchments based on the geological features of the catchment. (c) 2023 International Research and Training Centre on Erosion and Sedimentation/the World Association for Sedimentation and Erosion Research. Published by Elsevier B.V. All rights reserved.
• Pore connectivity influences mass transport in natural rocks: Pore structure, gas diffusion and batch sorption studies

  Xiaoqing Yuan, Qinhong Hu, Xiang Lin, Chen Zhao, Qiming Wang, Yukio Tachi, Yuta Fukatsu, Shoichiro Hamamoto, Marja Siitari-Kauppi, Xiaodong Li

  JOURNAL OF HYDROLOGY 618 129172 - 129172 0022-1694 2023/03 [Refereed]
   

  Six rocks (one granodiorite, one limestone, two chalks, one mudstone, and one dolostone) with different extents of heterogeneity at six different particle sizes (from 75 to 8000 & mu;m) were studied to describe the effects of pore connectivity on mass transport. The methods applied were (i) porosity measurement of granular rocks, (ii) an-alyses of gas-phase diffusive transport in a bed of packed particles, along with a solid quartz method at these six particle sizes being developed to identify the contribution of intraparticle diffusion, and (iii) batch sorption tests of multiple ions (anions and cations) with subsequent analyses of inductively coupled plasma-mass spectrometry. Granular porosity measurement results reveal that with decreasing particle sizes, the effective porosities for the "heterogenous" group of rocks (Grimsel granodiorite and Edwards limestone) increase, whereas the porosities of another "homogeneous" group (two Israel chalk samples, Japan mudstone, and Wyoming dolostone) remain constant. Gas diffusion results show that the intraparticle gas diffusion coefficient among these two sample groups, varying in the magnitude of 10-8 to 10-6 m2/s, are not directly correlated to the porosity differences. Moreover, the batch sorption work displays a different affinity of rocks for various tracers. For Grimsel grano-diorite, Japan mudstone, and Wyoming dolostone, the adsorption capacity of Sm3+ and Eu3+ increases as the particle size decreases. In general, this integrated research of grain size distribution, granular rock porosity, intraparticle diffusivity, and ionic sorption capacity gives insights into the pore connectivity effect on both physical and chemical transport behaviors for different lithologies and/or different particle sizes.
• Potassium buffering characteristics and detection of soils with challenges in evaluating radiocesium uptake risk of crops by exchangeable potassium

  Tetsuya Eguchi, Daigo Yamada, Takashi Hirayama, Kazuhiro Kohata, Noboru Kanno, Naoto Nihei, Shoichiro Hamamoto, Katashi Kubo, Takashi Saito, Takuro Shinano

  ARCHIVES OF AGRONOMY AND SOIL SCIENCE 69 (13) 2703 - 2720 0365-0340 2023/02 [Refereed]
   

  In surrounding areas influenced by the Fukushima Dai-ichi Nuclear Power Plant accident, the radiocesium uptake by crops was evaluated based on soil exchangeable K. As risk evaluation does not function effectively in several fields, K buffering was characterized using quantity/intensity (Q/I) relationship analysis to evaluate the availability of exchangeable K. The results of the analysis clearly explain the difficulty in the risk evaluation: i) difficulty in increasing exchangeable K, owing to retention as non-exchangeable K by vermiculite; ii) difficulty in retaining exchangeable K due to low K buffering capacity, reflecting the lack of K-selective clay minerals; and iii) difficulty in increasing soil solution K intensity due to high K buffering capacity, reflecting the abundance of K-selective clay minerals. Among the parameters calculated from the Q/I relationship analysis, beta values, corresponding to the retention rate of loaded K to the soil, for total K (beta t), exchangeable K (beta e), and non-exchangeable K (beta n) would be useful as simple indicators of soils with a predicament in the risk evaluation of radiocesium uptake by crops through exchangeable K. These soils showed distinctively low beta t values (0.18 or lower), high beta e value (0.37 or higher), or high beta n/beta t ratio (0.53 or higher).
• Effects of thermal properties of porous media on local thermal (non-)equilibrium heat transport

  Toshiyuki Bandai, Shoichiro Hamamoto, Gabriel C. Rau, Toshiko Komatsu, Taku Nishimura

  Journal of Groundwater Hydrology 65 (2) 125 - 139 0913-4182 2023 [Refereed]
   

  When analyzing convective heat transport, local thermal equilibrium (LTE) between the solid and fluid phases of water-saturated porous media is commonly assumed. However, experiments investigating the scope of validity of this assumption are lacking. We conducted heat transport experiments using two types of porous media having the same grain size (5 mm) but contrasting thermal properties (glass and polyoxymethylene) for different thermal Péclet numbers between 1.1 and 19.8. We used specifically crafted sensors to separately measure the temperature of the solid and fluid phases. Both LTE and local thermal non-equilibrium (LTNE) models were used to analyze the measurement data. While the LTE model was appropriate for all experimental conditions, small signatures of LTNE were detected. The experimental data and the sensitivity analysis using the LTNE model demonstrated that the volumetric heat capacity of solid plays a more significant role in causing LTNE than the solid thermal conductivity.
• A new exponential model for predicting soil gas diffusivity with varying degree of saturation

  M. M. T. Lakshani, T. K. K. Chamindu Deepagoda, Shoichiro Hamamoto, Bo Elberling, Wei Fu, Ting Yang, Jun Fan, Xiaoyi Ma, Timothy Clough, Kathleen M. Smits, T. G. Parameswaran, G. L. Sivakumar Babu, H. Chanakya

  Vadose Zone Journal 22 (1) 2023/01 [Refereed]
   

  Soil gas diffusivity (D-p/D-o, gas diffusion coefficients in soil and in free air, respectively) and its relation to soil moisture is of great importance for describing and quantifying essential provisional and regulatory functions associated with terrestrial ecosystems such as soil aeration and greenhouse gas (GHG) emissions. Because gas migration in terrestrial soil systems is predominantly diffusion controlled, soil gas diffusivity becomes a fundamental prerequisite to quantify diffusive gas fluxes. Descriptive-predictive models are often used to estimate D-p/D-o from easily measurable soil physical properties. Most of the available models take the form of power-law functions and often tend to mischaracterize soil moisture effects at high moisture regimes. Based on a wide range D-p/D-o data available in literature representing both intact and repacked soils, this study developed a novel air-saturation-dependent exponential (ASEX) gas diffusivity model to model D-p/D-o in relation to soil air saturation. The model variable alpha, which represents the diffusivity at half air saturation normalized by the same in complete soil air saturation, could potentially differentiate moisture effects on different soil structural states. For specific applications in intact soils, we propose corresponding alpha values for upper-limit (alpha = .6) and lower-limit (alpha = .05) estimates of diffusivity, while an average value (alpha = .3) for general applications in both intact and repacked soils. As expected, our model based on a few a priori measured supportive data showed a better performance over the classical predictive models that do not use such measurements. The new model was further used to derive useful implications to showcase soil density effects on D-p/D-o.
• Adaptability of Early–Winter Direct–Sowing Cultivation of Paddy Rice using Different Seed Coating Types at 11 Locations in Japan

  Kensaku SUZUKI, Junichi KASHIWAGI, Taiken NAKASHIMA, Kiyoshi NAGASUGA, Toshihiro MOCHIZUKI, Tomomi ABIKO, Masami FURUHATA, Youichi OHDAIRA, Masahiro CHIBA, Tosiyuki KIMURA, Shinji YANO, Mitsuki ABE, Akira MATSUDA, Hiroshi SAITO, Masaki SASAGAWA, Motonori TAKAHASHI, Taku NISHIMURA, Shoichiro HAMAMOTO, Takeshi TOKIDA, Masayoshi NISHI, Susumu YUI, Hiroyuki SHIMONO

  Japanese Journal of Crop Science 91 (4) 291 - 302 0011-1848 2022/10/05 [Refereed][Not invited]
   

  To clarify the adaptability of cultivation of paddy rice by direct sowing in early winter, we compared the seedling establishment at 11 locations in Japan in two seasons (2018/19 and 2019/20) using different coating types and sowing dates. Although winter–sown seeds (October, November, January) had poorer seedling establishment than spring-sown seed (April), seed coating decreased the gap between winter-sowing and spring-sowing. Seedling establishment was not affected by the sowing date between October and November in Aomori, Iwate, Akita, Yamagata (2 locations) and Fukushima prefectures over the two seasons. On the other hand, in Niigata prefecture, the seedling establishment was poorer in October than in November due to untimely germination after sowing, and in Mie, Hiroshima and Fukuoka prefectures, it was better in January than in November. In contrast, in Hokkaido, seedling establishment was better when sown in October than in November. The ratio of seedling establishment per unit seed survival rate was 55% (2018/19) and 69% (2019/20) for seeds sown in spring. The seedling establishment in 2019/20 was higher than in 2018/19 at many locations. The maximum seedling establishment at 11 locations ranged from 39% to 86%, which satisfied the target seedling establishment of 35%. These results showed that seed coating is effective over a wide area for improving seedling establishment of seeds direct sown in early winter.
• Water‐ and air‐filled pore networks and transport parameters under drying and wetting processes

  Shoichiro Hamamoto, Yushi Ohko, Yutaka Ohtake, Per Moldrup, Taku Nishimura

  Vadose Zone Journal 21 (4) 2022/07 [Refereed]
   

  The connectivity and tortuosity of fluid-filled pore networks in the water and air phases strongly influence the mass transport in porous media. Moisture conditions (water content and distribution) alter water- or air-filled pore networks. In this study, using a sand column with variable saturated conditions, water- and air-filled pore networks were analyzed using X-ray computed tomography (CT). Water and air transport parameters, including hydraulic conductivity, gas diffusion coefficient, and air permeability, were measured. The objectives were (a) to identify the effects of entrapped air on the water-filled pore network and hydraulic conductivity and (b) to understand the water- and air-filled pore networks and relevant transport parameters in the sand column during the drying and wetting processes. Measurements of hydraulic conductivity using quasisaturated samples showed that hydraulic conductivity was drastically reduced when smaller in situ air bubbles were present inside the sand column. At the same air-filled porosity, higher gas diffusivity and air permeability were obtained under wetting than those during drying. X-ray CT image analysis revealed that the air-filled pore network connectivity during wetting was higher than that during drying, resulting in enhanced gas transport parameters during the wetting process. The observed differences in water- and air-filled pore networks during drying and wetting processes are highly promising for future multiphase mass transport models in soils.
• Vertical migration of cesium in weathered granite soil under flowing water condition depending on Cs concentration and states of dissolved organic matter

  Takahiro Tatsuno, Shoichiro Hamamoto, Naoto Nihei, Taku Nishimura

  JOURNAL OF ENVIRONMENTAL MANAGEMENT 306 0301-4797 2022/03 [Refereed]
   

  After the accident at the Fukushima Daiichi nuclear power plant in Japan, the migration of radioactive cesium (Cs) in soils has become a crucial issue since this can negatively affect human health and the surrounding environment. Dissolved organic matter (DOM) may have different influences on Cs migration in soils depending on Cs adsorption sites with different selectivity. It is unclear how DOM affects the rapid migration of Cs in soils under flowing water conditions during rainfall events. This study evaluated the effects of DOM on Cs migration in weathered granite soil depending on Cs adsorption sites by conducting laboratory experiments under different DOM conditions and Cs concentrations in the liquid phase. Cs concentration can affect the fraction of Cs adsorbed onto differently selective sites, and DOM can have different influences on Cs migration in the soil accordingly. Under condition of high-Cs concentration, the DOM adsorbed on the soil reduced Cs migration due to increasing Cs electrostatic adsorption to less selective sites in the soil. Meanwhile, under low-Cs concentration, the DOM adsorbed on the soil enhanced Cs migration because the DOM on the soil decreased the Cs adsorption to highly selective sites. Furthermore, DOM in the liquid phase detached the Cs adsorbed on the less selective sites and enhanced Cs migration in the soil, regardless of the Cs concentration.
• Inhibited nanobubble transport in a saturated porous medium: Effects of deposited colloidal particles

  Takuya Sugimoto, Shoichiro Hamamoto, Taku Nishimura

  JOURNAL OF CONTAMINANT HYDROLOGY 242 0169-7722 2021/10 [Refereed]
   

  Nanobubbles have recently attracted much interest for their practical use and potential applications in environmental issues. The pre-existence of deposited colloidal particles in porous media commonly occurs when nanobubbles applied to porous media interact with deposited colloidal particles. However, the current understanding of the effect of the interactions with pre-deposited colloidal particles on nanobubble transport in saturated porous media remains incomplete, and the effects are often overlooked. Therefore, we performed 1D column experiments with sequential injections of colloidal and nanobubble suspensions to study the effect of predeposited materials on the retention and release of colloids and nanobubbles in packed glass beads. In this study, we used resonant mass measurements to measure the number concentrations of colloids and nanobubbles during transport experiments for the first time to distinguish between coexisting solid colloidal particles and nanobubbles with different buoyancies in mixed effluent during transport. The nanobubble retention increased because of the pre-existence of deposited colloidal particles, indicating that the deposited colloidal particles act as additional deposition sites and physical obstacles for nanobubbles through physicochemical (including hydrophobic) interactions. This study also provides a future reference for the applicability of resonant mass measurement to cotransport experiments of different buoyant particles, including colloids, nanobubbles, and oil droplets.
• Enhancement of developmentally regulated daidzein secretion from soybean roots in field conditions as compared with hydroponic culture

  Miwako Toyofuku, Fuki Okutani, Masaru Nakayasu, Shoichiro Hamamoto, Hisabumi Takase, Kazufumi Yazaki, Akifumi Sugiyama

  BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY 85 (5) 1165 - 1169 0916-8451 2021/04 [Refereed]
   

  Analyses of metabolite secretions by field-grown plants remain scarce. We analyzed daidzein secretion by field-grown soybean. Daidzein secretion was higher during early vegetative stages than reproductive stages, a trend that was also seen for hydroponically grown soybean. Daidzein secretion was up to 10 000-fold higher under field conditions than hydroponic conditions, leading to a more accurate simulation of rhizosphere daidzein content.
• Microbial Community Structures in Terrestrial Subsurface Sediments from the Southern Kanto Plain, Japan

  Satoshi Ohkubo, Takeshi Saito, Muhammad Abul Kalam Azad, Hiromitsu Kawai, Wataru Suda, Shin Kore-eda, Shoichiro Hamamoto, Hirotaka Saito, Takato Takemura, Toshiko Komatsu, Jun-ichi Ohnishi

  GEOMICROBIOLOGY JOURNAL 37 (7) 595 - 602 0149-0451 2020/07 [Refereed][Not invited]
   

  Microbial community structure reflects the surrounding natural environment and changes to that environment. Although the subsurface at 5-100 m depth is important for human activities and there are potential risks of environmental pollution in this region, there have been only a few reports of subsurface microbial community structures in terrestrial areas. We investigated the diversity and community compositions of Bacteria and Archaea in boring cores collected from various depths at three different sites in the southern Kanto Plain, Japan. The results of 16S rRNA gene amplicon sequencing using MiSeq showed that the microbial community composition varied with the geological unit. Proteobacteria (Alphaproteobacteria and Gammaproteobacteria) were dominant members within sediments accumulated during the Pleistocene in the Musashino Upland. In contrast, Acidobacteria and Chloroflexi characteristically appeared in the Holocene layers of the Arakawa Lowland. These data suggest that the subsurface microbial composition is controlled by the geological features of the sediments.
• Characterization and comparison of groundwater quality and redox conditions in the Arakawa Lowland and Musashino Upland, southern Kanto Plain of the Tokyo Metropolitan area, Japan

  Takeshi Saito, Lorenzo Spadini, Hirotaka Saito, Jean M. F. Martins, Laurent Oxarango, Takato Takemura, Shoichiro Hamamoto, Per Moldrup, Ken Kawamoto, Toshiko Komatsu

  SCIENCE OF THE TOTAL ENVIRONMENT 722 0048-9697 2020/06 [Refereed][Not invited]
   

  Groundwater is essential for the Earth biosphere but is often contaminated by harmful chemical compounds due to both anthropogenic and natural causes. A key factor controlling the fate of harmful chemicals in groundwater is the reduction/oxidation (redox) conditions. The formation factors for the groundwater redox conditions are insufficiently understood. In this study, long-term groundwater quality beneath one of the world megacities was monitored and evaluated. We measured and compared hydrogeochemical conditions including groundwater quality (35 chemical parameters) and redox conditions of five aquifers in the Arakawa Lowland and Musashino Upland, southern Kanto Plain of the TokyoMetropolitan area, Japan. Monitoring results suggested the following: The main origin of groundwater is precipitation in both the Lowland and Upland areas. The three aquifers in the Arakawa Lowland are likely fully separated, with one unconfined and two confined aquifers under iron reducing and methanogenic conditions, respectively. Oppositely, in the Musashino Upland, the water masses in the two aquifers are likely partly connected, under aerobic conditions, and undergoing the same groundwater recharge and flow processes under similar hydrogeological conditions. The different groundwater redox conditions observed are likely caused by the very different groundwater residence times for the Arakawa Lowland and Musashino Upland. (C) 2020 Elsevier B.V. All rights reserved.
• Rhizosphere modelling reveals spatiotemporal distribution of daidzein shaping soybean rhizosphere bacterial community

  Fuki Okutani, Shoichiro Hamamoto, Yuichi Aoki, Masaru Nakayasu, Naoto Nihei, Taku Nishimura, Kazufumi Yazaki, Akifumi Sugiyama

  PLANT CELL AND ENVIRONMENT 43 (4) 1036 - 1046 0140-7791 2020/04 [Refereed][Not invited]
   

  Plant roots nurture a wide variety of microbes via exudation of metabolites, shaping the rhizosphere's microbial community. Despite the importance of plant specialized metabolites in the assemblage and function of microbial communities in the rhizosphere, little is known of how far the effects of these metabolites extend through the soil. We employed a fluid model to simulate the spatiotemporal distribution of daidzein, an isoflavone secreted from soybean roots, and validated using soybeans grown in a rhizobox. We then analysed how daidzein affects bacterial communities using soils artificially treated with daidzein. Simulation of daidzein distribution showed that it was only present within a few millimetres of root surfaces. After 14 days in a rhizobox, daidzein was only present within 2 mm of root surfaces. Soils with different concentrations of daidzein showed different community composition, with reduced alpha-diversity in daidzein-treated soils. Bacterial communities of daidzein-treated soils were closer to those of the soybean rhizosphere than those of bulk soils. This study highlighted the limited distribution of daidzein within a few millimetres of root surfaces and demonstrated a novel role of daidzein in assembling bacterial communities in the rhizosphere by acting as more of a repellant than an attractant.
• Effect of air mobility in a soil pipe on water flow through a model hillslope after pipe clogging

  Takuhei Yamasaki, Shoichiro Hamamoto, Taku Nishimura

  EARTH SURFACE PROCESSES AND LANDFORMS 45 (4) 905 - 911 0197-9337 2020/03 [Refereed][Not invited]
   

  Soil pipes (continuous macropores expanding laterally in the soil subsurface) are a key factor controlling hillslope water cycles and sediment transport. Soil pipes usually enhance slope stability under rainfall events through their high water drainage ability, and pipe clogging by sediments is regarded as a risk for slope failure. In this study, we conducted a bench-scale pipe clogging experiment to clarify the effect of air mobility in soil pipes on water flow and water pressure build-up in the slope at the clogged point. Before pipe clogging, the soil pipe drained rainwater effectively and lowered the groundwater table. After the pipe clogging event, the mobility of air in the soil pipe before the clogging determined the water flow in the slope. When the air in the soil pipe connected to the atmosphere and moved freely, the water level in the soil pipe increased at the pipe clogging, and water pressure build-up was limited near the pipe outlet. On the other hand, when air in the soil pipe was entrapped by the clogging, water pressure suddenly increased, and the groundwater table of the whole slope rose correspondingly. This study clearly demonstrated the importance of pipe morphology with respect to air connectivity between the pipe and atmosphere to elucidate the water flow and slope stability during the pipe clogging event. (c) 2019 John Wiley & Sons, Ltd.
• Effects of the dissolved organic matter on Cs transport in the weathered granite soil

  Takahiro Tatsuno, Shoichiro Hamamoto, Naoto Nihei, Taku Nishimura

  Journal of Environmental Management 254 0301-4797 2020/01 [Refereed][Not invited]
   

  It is important to understand the migration of Cesium (Cs) in soils, particularly after the nuclear power plant accident at Fukushima Dai-ichi, Japan. Dissolved organic matter (DOM) is one of factors affecting the migration of Cs in soils under flowing water conditions. We investigated the effect of DOM on the migration of Cs adsorbed to the clay planar site via laboratory column experiments. The sequence of DOM application had a significant influence on Cs transport in the soil. When DOM was applied concurrently with or prior to Cs application, the DOM adsorbed on to the clay planar site adsorbed onto the soil solid surface and enhanced Cs adsorption; consequently, it slowed Cs migration in the soil. In particular, in the case of DOM loaded prior to the application of Cs solution, a noticeable delay in Cs migration was observed. On the other hand, when DOM was applied to the soil where the Cs solution had been previously applied, the DOM desorbed Cs from the soil. DOM in liquid phase enhanced the migration of Cs through the formation of binding to organic matter. Majority of Cs affected by DOM was the exchangeable fraction that adsorbed to the clay planar site. In other words, DOM attached to the soil would adsorb Cs as a easily exchangeable form and depress migration of Cs. On the other hand, DOM in the soil solution may up take adsorbed Cs from the soil and enhanced the transport in the form of Cs bound to DOM.
• Evaluation of Autoclaved Aerated Concrete Fines for Removal of Cd(II) and Pb(II) from Wastewater

  G. M. P. Kumara, Ken Kawamoto, Takeshi Saito, Shoichiro Hamamoto, Shingo Asamoto

  JOURNAL OF ENVIRONMENTAL ENGINEERING 145 (11) 0733-9372 2019/11 [Refereed][Not invited]
   

  Along with the increase of autoclaved aerated concrete (AAC) production, the amount of scrap waste (industrial by-products) is increasing. AAC waste, however, is not yet being fully reused or recycled and is discarded without any treatment in most developing countries. In this study, AAC fines were tested as effective and economic adsorbents for the removal of Cd2+ and Pb2+ from wastewater. A series of batch adsorption experiments were carried out using AAC with three different particle sizes (<0.105, 0.105-2, and 2-4.75 mm) to examine effects of the particle size, initial metal concentration (Ci), initial pH (pHi), ionic strength, contact time, and competitive metals. For comparing the adsorption characteristics and capacities, crushed concrete fines and a fine sand were also used. Results showed that the adsorption kinetic data were well fitted to the pseudo-second-order kinetics model for all tested materials. Pb2+ adsorption was independent of pHi and ionic strength for AAC fines, whereas Cd2+ adsorption varied depending on pHi and decreased drastically at pHi <= 7. Based on the results from adsorption isotherms, the Freundlich model fitted well (R2>0.90) to the data for 300 <= Ci <= 5,000 mg/L, whereas the Langmuir model was applicable (R2>0.99) to the data for Ci <= 2,000 mg/L. The maximum adsorption capacity of each particle size of AAC exhibited almost the same adsorption capacity for Cd2+ (15 mg/g) and Pb2+ (>250 mg/g), which are similar to or higher than the values of other types of adsorbents in previous studies. The metal removal by AAC is controlled mainly by ion exchange, surface complexation, and surface precipitation. In particular, the Ca2+ ion exchange on the hydrated adsorbent surface is the dominant adsorption mechanism at the early stage of adsorption. The selectivity sequence of metal adsorptions became Pb2+>Cu2+>Ni2+>Cd2+>Zn2+ for AAC, and the existence of Pb2+ and Cu2+ in wastewater highly impeded the Cd2+ adsorption onto AAC fines.
• Methane eruptions from landfill final cover soil during rainfall events in laboratory experiments

  Satoshi Izumoto, Shoichiro Hamamoto, Ken Kawamoto, Masanao Nagamori, Taku Nishimura

  SOILS AND FOUNDATIONS 59 (4) 1052 - 1062 0038-0806 2019/08 [Refereed][Not invited]
   

  Landfill sites are significant sources of greenhouse gases, particularly methane. It is believed that methane gas eruptions occur under a surface ponding condition during rainfall events. In this study, based on laboratory column experiments in which mixed gas was applied to variably compacted soil columns (10 cm in diameter and 30.5 cm in height) under different rainfall intensities, the effects of the bulk density of the landfill cover soil, the gas injection rates, and the rainfall intensities on the gas eruption phenomenon were investigated. The gas pressure and the water content were monitored during rainfall events. The main results were that (1) an episodic gas compression and eruption cycle was observed under a surface ponding condition, (2) gas eruptions occurred at a higher gas pressure in the soil with a higher dry bulk density, and (3) a higher gas injection rate resulted in continuous gas eruptions. The monitoring of the gas eruption flux and gas concentration in the soil columns, using oxygen-mixed gas as an injected gas, showed that longer gas compression led to higher gas fluxes during the gas eruptions. The concentration of gas in the soil increased over time because of the upward gas flow in accordance with the eruptions. The calculation of the oxygen mass balance indicated that the eruptions had slightly promoted the emission of gas from that which had been stored in the soil prior to the rainfall events. (C) 2019 Production and hosting by Elsevier B.V. on behalf of The Japanese Geotechnical Society.
• Nanobubble Retention in Saturated Porous Media under Repulsive van der Waals and Electrostatic Conditions

  Shoichiro Hamamoto, Takuya Sugimoto, Takato Takemura, Taku Nishimura, Scott A. Bradford

  Langmuir 35 (21) 6853 - 6860 0743-7463 2019/05/28 [Refereed][Not invited]
   

  An understanding of nanobubble (NB) migration in porous media is needed for potential environmental applications. The solution chemistry is well known to be a critical factor in determining interactions of other colloids and nanoparticles with surfaces. However, little quantitative research has examined the influence of solution chemistry on NB transport. One-dimensional column experiments were therefore conducted to investigate the transport, retention, and release of NBs in glass beads under different solution chemistry conditions. NB concentrations in the effluent were reduced with an increase in ionic strength (IS) or a decrease in pH due to a reduction in the repulsive force between the glass surface and NBs, especially when the solution contained Ca2+ as compared to Na+ and for larger NBs. This result was somewhat surprising because electrostatic and van der Waals interactions for NBs were both repulsive on a homogeneous glass bead surface. NB retention on the surface was explained by ubiquitous nanoscale roughness on the glass beads that significantly lowered the energy barrier and localized attractive charge heterogeneity and/or hydrophobic interactions. In contrast to Na+, adsorbed Ca2+ ions produced charge heterogeneity that enhanced NB retention and inhibited release with IS reduction.
• Absorption of radioceasium in soybean

  Naoto Nihei, Shoichiro Hamamoto

  Agricultural Implications of the Fukushima Nuclear Accident (III): After 7 Years 27 - 33 2019/01/30 

  Radioactive materials, primarily radiocesium (134Cs + 137Cs), were released into the environment by the Fukushima Daiichi Nuclear Power Plant accident in March 2011. The percentage of soybean plants that had a concentration of radiocesium over 100 Bq/kg was higher than that of other crops. To examine the reason why the concentration of radiocesium in soybeans was high, its concentration and distribution in seeds were analyzed and compared to rice. Potassium fertilization is one of the most effective countermeasures to reduce the radiocesium uptake by soybean and nitrogen fertilizer promotes soybean growth. To use potassium and nitrogen fertilizers safely and efficiently, applied potassium behavior in soil and the effect of nitrogen fertilizer on radiocesium absorption in soybean were studied.
• Linking pore network structure derived by microfocus X-ray CT to mass transport parameters in differently compacted loamy soils

  Arjun Baniya, Ken Kawamoto, Shoichiro Hamamoto, Toshihiro Sakaki, Takeshi Saito, Karin Mueller, Per Moldrup, Toshiko Komatsu

  SOIL RESEARCH 57 (6) 642 - 656 1838-675X 2019 [Refereed]
   

  Mass transport in soil occurs through the soil pore network, which is highly influenced by pore structural parameters such as pore-size distribution, porosity, pore tortuosity, and coordination number. In this study, we visualised the networks of meso- and macro-pores (typical pore radius r >= 10 mu m) using microfocus X-ray computed tomography (MFXCT) and evaluated pore structural parameters of two loamy soils from Japan and New Zealand packed at different degrees of compaction. The effect of compaction on pore structural parameters and relationships between pore structural parameters and measured mass transport parameters were examined. Results showed a clear influence of compaction on pore structural parameters, with the MFXCT-derived mean pore radii and pore tortuosities decreasing and the mean pore coordination number increasing with increasing dry bulk density. Especially, pores with r > 80 mu m became finer or were not well formed due to compaction. The MFXCT-derived pore structural parameters were not well correlated with the equivalent pore radii from measured water retention curves. However, volumetric surface areas and pore-network connectivity-tortuosity factors derived from MFXCT allowed a fair prediction of several important mass transport parameters such as saturated hydraulic conductivities, soil-gas diffusion coefficients, and soil-air permeabilities. Further studies are needed to link micro-pores with radii smaller than the X-ray CT resolution to meso- and macro-pores visualised by X-ray CT to improve the prediction of mass transport parameters in soil.
• Effects of bubble characteristics and solution chemistry on nano bubbles transport in saturated porous media

  Shoichiro Hamamoto, Akihide Ejiri, Thuyet Dang, Naoto Nihei, Takato Takemura, Kenichiro Suzuki, Scott Bradford, Taku Nishimura

  ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY 256 0065-7727 2018/08 [Refereed]
  
• USING MULTICYCLE MERCURY INTRUSION POROSIMETRY TO INVESTIGATE HYSTERESIS PHENOMENON OF DIFFERENT POROUS MEDIA

  Gao, Zhiye, Hu, Qinhong, Hamamoto, Shoichiro

  Journal of Porous Media 21 (7) 607 - 622 1091-028X 2018 [Refereed][Not invited]
   

  The intrusion-extrusion hysteresis phenomenon is commonly observed during mercury porosimetry analysis. A change in contact angle between intrusion and extrusion processes, and the effect of ink-bottle pores, are generally considered as the two main mechanisms of hysteresis. This work is to further investigate the hysteresis phenomenon for different building materials (concrete and red brick) and natural rocks (shales, dolomite, tuff, and white chalk) using an approach of multicycle mercury intrusion porosimetry. Different correction methods, including the modified Kloubek method with variable constant and contact angle correction method, are used to account for the hysteresis phenomenon for different types of porous media. For all shale samples with quite a number of nanosized pores (> 60% for pore-throats < 100 nm), our results show that they exhibit more complicated hysteresis than other porous media used in this study, and the modified Kloubek method considering both variable contact angle and surface tension exhibits a better correction than the contact angle correction method. Although for other porous media tested here, the contact angle correction method could obtain an equivalent effect to the modified Kloubek method. In summary, multicycle mercury intrusion porosimetry could help elucidate the effect of ink-bottle pores for pore size distribution analysis and evaluate the effect of contact angle changes on the hysteresis phenomenon.
• Saturation-dependent gas transport in sand packs: Experiments and theoretical applications

  Ghanbarian, Behzad, Hamamoto, Shoichiro, Kawamoto, Ken, Sakaki, Toshihiro, Moldrup, Per, Nishimura, Taku, Komatsu, Toshiko

  Advances in Water Resources 122 139 - 147 0309-1708 2018/12 [Refereed][Not invited]
   

  Understanding gas transport in porous media and its mechanism has broad applications in various research areas, such as carbon sequestration in deep saline aquifers and gas explorations in reservoir rocks. Gas transport is mainly controlled by pore space geometrical and morphological characteristics. In this study, we apply a physically-based model developed using concepts from percolation theory (PT) and the effective-medium approximation (EMA) to better understand diffusion and permeability of gas in packings of angular and rounded sand grains as well as glass beads. Two average sizes of grain i.e., 0.3 and 0.5 mm were used to pack sands in a column of 6 cm height and 4.9 cm diameter so that the total porosity of all packs was near 0.4. Water content, gas-filled porosity (also known as gas content), gas diffusion, and gas permeability were measured at different capillary pressures. The X-ray computed tomography method and the 3DMA-Rock software package were applied to determine the average pore coordination number z. Results showed that both saturation-dependent diffusion and permeability of gas showed almost linear behavior at higher gas-filled porosities, while deviated substantially from linear scaling at lower gas saturations. Comparing the theory with the diffusion and permeability experiments showed that the determined value of z ranged between 2.8 and 5.3, not greatly different from X-ray computed tomography results. The obtained results clearly indicate that the effect of the pore-throat size distribution on gas diffusion and permeability was minimal in these sand and glass bead packs.
• Effects of pH on nano-bubble stability and transport in saturated porous media

  Hamamoto, Shoichiro, Takemura, Takato, Suzuki, Kenichiro, Nishimura, Taku

  Journal of Contaminant Hydrology 208 61 - 67 0169-7722 2018/01 [Refereed][Not invited]
   

  An understanding of nano-scale bubble (NB) transport in porous media is important for potential application of NBs in soil/groundwater remediation. It is expected that the solution chemistry of NB water highly influences the surface characteristics of NBs and porous media and the interaction between them, thus affecting the stability and transport characteristics of NB. In this study, in addition to stability experiments, one-dimensional column transport experiments using glass beads were conducted to investigate the effects of pH on the NB transport behavior. The results showed that the NBs were more stable under higher pH. Column transport experiments revealed that entrapment of NBs, especially larger ones, was enhanced in lower-pH water, likely suggesting pH-dependent NB attachment and physical straining, both of which are also probably influenced by bubble size. Although relatively smaller NBs were released after switching the eluting fluid to one with lower ionic strength, most of the NBs in lower-pH water were still retained in the porous media even altering the chemical condition.
• Monitoring of methane emission from a landfill site in daily and hourly time scales using an automated gas sampling system

  Izumoto, Satoshi, Hamamoto, Shoichiro, Kawamoto, Ken, Nagamori, Masanao, Nishimura, Taku

  Environmental Science and Pollution Research 25 (24) 24500 - 24506 0944-1344 2018/08 [Refereed][Not invited]
   

  Landfill sites are significant sources of methane gas globally. Understanding the temporal variabilities of methane emissions from landfill sites is necessary for estimating such emissions. In this study, an automated monitoring system was used to monitor methane emission flux and concentration on daily and hourly time scales at a landfill site. Measured methane emission fluxes were almost negligible in the studied area. However, methane concentration at landfill surface at nighttime was significantly higher than those in the daytime, which demonstrates the importance of investigating methane emissions at an hourly time scale, including during nighttime. The daily and hourly variations in methane concentration were well correlated with either soil temperature or volumetric water content near the surface. The obtained relations indicate that the automated monitoring system measurements can facilitate a more comprehensive understanding of the methane emission mechanisms at different time scales.
• Potassium behavior and clay mineral composition in the soil with low effectiveness of potassium application

  Kubo, Katashi, Hirayama, Takashi, Fujimura, Shigeto, Eguchi, Tetsuya, Nihei, Naoto, Hamamoto, Shoichiro, Takeuchi, Megumi, Saito, Takashi, Ota, Takeshi, Shinano, Takuro

  Soil Science and Plant Nutrition 64 (2) 265 - 271 0038-0768 2018 [Refereed][Not invited]
   

  Increasing exchangeable potassium (ExK) content in soil to an appropriate level is important to mitigate the transfer of radioactive cesium to crops. We focused on a buckwheat (Fagopyrum esculentum Moench) field with a low ExK content, despite the application of K, in Fukushima Prefecture, Japan (Field A), following the Tokyo Electric Power Company Fukushima Dai-ichi (No. 1) Nuclear Power Plant accident in March 2011. We examined the relationship between K concentration and clay mineral composition in the soil of Field A and compared the findings with another field in Fukushima Prefecture (Field B) to clarify whether K applied to the soil was leached or remaining fixed. Pot experiments showed that K concentration in water seepage from pots following irrigation was significantly lower in pots from Field A than in those from Field B. Soil ExK content after soybean cultivation was lower in soils of Field A than those of Field B. These results indicate that K applied to Field A was fixed in the soil. Analysis of clay mineral composition confirmed the distinctive vermiculitic nature of Field A soils. This clay mineralogy would be associated with the higher K fixation ability of Field A than Field B soils. This study demonstrated that K fixation in vermiculite was a factor preventing the increase in ExK content from K application to Field A.
• The effect of particle size on thermal and solute dispersion in saturated porous media

  Toshiyuki Bandai, Shoichiro Hamamoto, Gabriel C. Rau, Toshiko Komatsu, Taku Nishimura

  INTERNATIONAL JOURNAL OF THERMAL SCIENCES 122 74 - 84 1290-0729 2017/12 [Refereed][Not invited]
   

  Thermal dispersion, caused by fluid velocity and temperature fluctuations in the pore space and the effects of hydrodynamic mixing on the temperature field, controls convective heat transport in saturated porous media. While the thermal dispersion coefficient, a governing parameter in the thermal equilibrium model (TEM), has been investigated for natural systems, the dependence of the thermal dispersion coefficient on particle size remains undetermined. Previous research found that the relationship between the thermal dispersion coefficient and flow velocity follows a power law and that there may be a temperature difference between the solid and fluid phase (thermal non-equilibrium). However, experiments are limited to discrete particle sizes and comparison of the dispersion-velocity relationship is impeded by different experimental approaches. We conducted a series of separate heat and solute transport experiments in a column filled with uniform porous media consisting of different sized glass spheres for a range of flow velocities. The thermal and solute dispersion coefficients obtained from experimental measurements were correlated with flow velocities through the thermal or solute Peclet number. Our results demonstrate that, while solute dispersion is independent of particle size, the dependence of the TEM based thermal dispersion coefficient on flow rates is influenced by the particle size. This is caused by the fact that, unlike solute transport, heat exchanges between fluid and particles and that this induces thermal non-equilibrium between both phases. The results have significant implications for quantifying forced convective heat transport in natural porous media because thermal non equilibrium between the phases is not considered. The porous media particle size must be considered when selecting appropriate values for the thermal dispersion coefficient. (C) 2017 Elsevier Masson SAS. All rights reserved.
• Synthesis and Secretion of Isoflavones by Field-Grown Soybean

  Akifumi Sugiyama, Yumi Yamazaki, Shoichiro Hamamoto, Hisabumi Takase, Kazufumi Yazaki

  PLANT AND CELL PHYSIOLOGY 58 (9) 1594 - 1600 0032-0781 2017/09 [Refereed][Not invited]
   

  Isoflavones play important roles in rhizosphere plant-microbe interactions. Daidzein and genistein secreted by soybean roots induce the symbiotic interaction with rhizobia and may modulate rhizosphere interactions with microbes. Yet despite their important roles, little is known about the biosynthesis, secretion and fate of isoflavones in field-grown soybeans. Here, we analyzed isoflavone contents and the expression of isoflavone biosynthesis genes in field-grown soybeans. In roots, isoflavone contents and composition did not change with crop growth, but the expression of UGT4, an isoflavone-specific 7-O-glucosyltransferase, and of ICHG (isoflavone conjugates hydrolyzing beta-glucosidase) was decreased during the reproductive stages. Isoflavone contents were higher in rhizosphere soil than in bulk soil during both vegetative and reproductive stages, and were comparable in the rhizosphere soil between these two stages. We analyzed the degradation dynamics of daidzein and its glucosides to develop a model for predicting rhizosphere isoflavone contents from the amount of isoflavones secreted in hydroponic culture. Conjugates of daidzein were degraded much faster than daidzein, with degradation rate constants of 8.51 d(-1) for malonyldaidzin and 11.6 d(-1) for daidzin, vs. 9.15 x 10(-2) d(-1) for daidzein. The model suggested that secretion of isoflavones into the rhizosphere is higher during vegetative stages than during reproductive stages in field-grown soybean.
• Effects of Flow Rate and Gas Species on Microbubble and Nanobubble Transport in Porous Media

  Hamamoto, Shoichiro, Nihei, Naoto, Ueda, Yoshikatsu, Moldrup, Per, Nishimura, Taku

  Journal of Environmental Engineering 143 (7) 0733-9372 2017/07 [Refereed][Not invited]
   

  Transport of microbubbles and nanobubbles (MNBs) in porous media has drawn increasing attention as a promising technology for soil and groundwater remediation. Understanding the transport mechanisms of MNBs in soils is essential to optimize MNB-based remediation techniques. In this study, effects of flow rates and bubble gas species on transport characteristics of MNBs were investigated in columns packed with glass beads. Microbubbles and nanobubbles were created by either air or oxygen injection to the columns at different flow rates. All results showed marked entrapment of MNBs inside the columns and relatively higher retardation of MNBs with smaller bubble size. The entrapment was enhanced for air-based MNBs under lower flow rate. A convection-dispersion model including bubble attachment could well capture the obtained effluent curves for MNB transport at high flow conditions. For low flow conditions, a model including bubble attachment-detachment and straining terms best described the data. The fitted model parameters suggested that irreversible straining is an important deposition mechanism for MNB transport in porous media. (C) 2017 American Society of Civil Engineers.
• Closure to discussion of "Pore network structure linked by X-ray CT to particle characteristics and transport parameters" by Hamamoto S., Moldrup P., Kawamoto K., Sakaki T., Nishimura T., and Komtatsu, T

  Hamamoto, Shoichiro, Moldrup, Per, Kawamoto, Ken, Sakaki, Toshihiro, Nishimura, Taku, Komatsu, Toshiko

  Soils and Foundations 57 (5) 901 - 903 0038-0806 2017/10 [Refereed][Not invited]
  
• Estimation of the Vertical Distribution of Radiocesium in Soil on the Basis of the Characteristics of Gamma-Ray Spectra Obtained via Aerial Radiation Monitoring Using an Unmanned Helicopter

  Ochi, Kotaro, Sasaki, Miyuki, Ishida, Mutsushi, Hamamoto, Shoichiro, Nishimura, Taku, Sanada, Yukihisa

  International Journal of Environmental Research and Public Health 14 (8) 1660-4601 2017/08 [Refereed][Not invited]
   

  After the Fukushima Daiichi Nuclear Power Plant accident, the vertical distribution of radiocesium in soil has been investigated to better understand the behavior of radiocesium in the environment. The typical method used for measuring the vertical distribution of radiocesium is troublesome because it requires collection and measurement of the activity of soil samples. In this study, we established a method of estimating the vertical distribution of radiocesium by focusing on the characteristics of gamma-ray spectra obtained via aerial radiation monitoring using an unmanned helicopter. The estimates are based on actual measurement data collected at an extended farm. In this method, the change in the ratio of direct gamma rays to scattered gamma rays at various depths in the soil was utilized to quantify the vertical distribution of radiocesium. The results show a positive correlation between the abovementioned and the actual vertical distributions of radiocesium measured in the soil samples. A vertical distribution map was created on the basis of this ratio using a simple equation derived from the abovementioned correlation. This technique can provide a novel approach for effective selection of high-priority areas that require decontamination.
• Relationship between trace elements and depositional environments in shallow sediments: a case study from Southern Kanto Plain, Central Japan

  Ueshima, Masato, Takemura, Takato, Saito, Takeshi, Ito, Yoshiharu, Hamamoto, Shoichiro, Saito, Hirotaka, Komatsu, Toshiko

  Environmental Earth Sciences 76 (18) 1866-6280 2017/09 [Refereed][Not invited]
   

  Underground developments such as subways and shopping facilities have been increasing in number and magnitude in the relatively shallow subsurface of many urban areas where the earth materials commonly are composed of marine sediments. Marine sediments can contain significant amounts of toxic trace elements such as arsenic, boron, and lead. Changes in the subsurface environment caused by excavation and construction in underground developments could potentially cause these toxic elements to be dissolved into pore water of the sediments, which might lead to groundwater pollution. The purpose of this study is to investigate correlations among chemical properties of marine sediments, such as pH and electrical conductivity (EC), concentrations of toxic trace elements, and stratigraphic characteristics of the sediments. We selected three sites with different stratigraphic settings in the southern Kanto Plain around the Tokyo Metropolis. We collected core samples from shallow strata at a site in the Arakawa Lowland, southern Saitama, and at two sites in the Musashino Upland, Middle Tokyo. All sites have both marine and non-marine sediments up to 50-60 m in thickness. We determined trace element concentrations in the pore water, pH, EC, and loss on ignition. The results show that (1) the marine sediments tend to have low pH, high EC, and high sulfur concentration compared to the non-marine sediments (2) the concentration of most of the soluble heavy metals vary depending on the concentration of sulfate, the pH, and the formation processes of the strata, (3) the arsenic concentration is not related to sulfur concentration but apparently to Fe and Al concentrations, (4) the boron concentration is not related to any other properties implying that the boron level is independent of and cannot be predicted by common chemical properties, and (5) for all three sites, concentrations of most of the trace elements, EC, pH, and sulfate concentration were correlated with each other. This study shows that the concentration and potential mobilization of many toxic trace elements in marine sediments could be predicted by easily measurable pore water chemical properties such as pH and EC. This could be useful for predicting and avoiding the risk of groundwater pollution during underground development projects.
• Determination of the role of entrapped air in water flow in a closed soil pipe using a laboratory experiment

  Yamasaki, Takuhei, Imoto, Hiromi, Hamamoto, Shoichiro, Nishimura, Taku

  Hydrological Processes 31 (21) 3740 - 3749 0885-6087 2017/10 [Refereed][Not invited]
   

  Soil pipes, continuous macropores parallel to the soil surface, are an important factor in hillslope hydrological processes. However, the water flow dynamics in soil pipes, especially closed soil pipes, are not well understood. In this study, the water and air dynamics within closed soil pipes have been investigated in a bench-scale laboratory experiment by using a soil box with an artificial acrylic soil pipe. In order to grasp the state of water and air within the soil pipe, we directly measured the existing soil pipe flow and air pressure in the soil pipe. The laboratory experiment showed that air in the soil pipe had an important role in the water flow in the closed soil pipe. When air entrapment occurred in the soil pipe before the soil matrix around the soil pipe was saturated with water, water intrusion in the soil pipe was prevented by air entrapped in the pipe, which inhibited the soil pipe flow. This air entrapment in the soil pipe was controlled by the soil water and air flow. Moreover, after the soil pipe flow started, the soil pipe was not filled completely with water even when the soil pipe was completely submerged under the groundwater table. The entrapped air in the soil pipe prevented further water intrusion in the soil pipe.
• Pore network structure linked by X-ray CT to particle characteristics and transport parameters

  Shoichiro Hamamoto, Per Moldrup, Ken Kawamoto, Toshihiro Sakaki, Taku Nishimura, Toshiko Komatsu

  SOILS AND FOUNDATIONS 56 (4) 676 - 690 0038-0806 2016/08 [Refereed][Not invited]
   

  Mass transport in soils occurs through pore networks that are highly affected by basic physical properties such as the degree of compaction, and particle size and shape. In this study, micro-focus X-ray computed tomography (CT) was used to obtain information on the pore network structure at different compaction levels for repacked columns of sands and glass beads representing different size fractions and particle shapes. Mass transport parameters, including gas diffusion coefficient (D-p) and air permeability (k(a)) at variably saturated conditions, were measured on the same columns using standard methods, and literature data on saturated hydraulic conductivity (K-sat) for the same materials were analyzed. A comparison of X-ray CT derived pore network structure and physical parameters showed that the round sands and glass beads exhibited larger pores, a higher pore coordination number, and a lower volumetric surface area than that of angular sands at the same particle size, resulting in higher K-sat as well as higher D-p and k(a) under relatively dry conditions. The X-ray CT derived the mean pore diameter (d), and the pore coordination number (C-n) for each material correlated well with key gas transport properties such as percolation thresholds and pore network connectivity. A predictive D-p model from wet to dry conditions based fully on X-ray CT derived parameters (d and C-n) was developed and showed good agreement with measured D-p for both round and angular sands. (C) 2016 The Japanese Geotechnical Society. Production and hosting by Elsevier B.V.
• Temperature change affected groundwater quality in a confined marine aquifer during long-term heating and cooling

  Takeshi Saito, Shoichiro Hamamoto, Takashi Ueki, Satoshi Ohkubo, Per Moldrup, Ken Kawamoto, Toshiko Komatsu

  WATER RESEARCH 94 120 - 127 0043-1354 2016/05 [Refereed][Not invited]
   

  Global warming and urbanization together with development of subsurface infrastructures (e.g. subways, shopping complexes, sewage systems, and Ground Source Heat Pump (GSHP) systems) will likely cause a rapid increase in the temperature of relatively shallow groundwater reservoirs (subsurface thermal pollution). However, potential effects of a subsurface temperature change on groundwater quality due to changed physical, chemical, and microbial processes have received little attention. We therefore investigated changes in 34 groundwater quality parameters during a 13-month enhanced heating period, followed by 14 months of natural or enhanced cooling in a confined marine aquifer at around 17 m depth on the Saitama University campus, Japan. A full-scale GSHP test facility consisting of a 50 m deep U-tube for circulating the heat-carrying fluid and four monitoring wells at 1, 2, 5, and 10 m from the U-tube were installed, and groundwater quality was monitored every 1-2 weeks. Rapid changes in the groundwater level in the area, especially during the summer, prevented accurate analyses of temperature effects using a single-well time series. Instead, Dual-Well Analysis (DWA) was applied, comparing variations in subsurface temperature and groundwater chemical concentrations between the thermally-disturbed well and a non-affected reference well. Using the 1 m distant well (temperature increase up to 7 degrees C) and the 10 m distant well (non-temperature-affected), the DWA showed an approximately linear relationships for eight components (B, Si, Li, dissolved organic carbon (DOC), Mg2+, NH4+, Na+, and K+) during the combined 27 months of heating and cooling, suggesting changes in concentration between 4% and 31% for a temperature change of 7 degrees C. (C) 2016 Elsevier Ltd. All rights reserved.
• Temperature effects on solute diffusion and adsorption in differently compacted kaolin clay

  Ei Ei Mon, Shoichiro Hamamoto, Ken Kawamoto, Toshiko Komatsu, Per Moldrup

  ENVIRONMENTAL EARTH SCIENCES 75 (7) 562(1) - 562(9) 1866-6280 2016/04 [Refereed][Not invited]
   

  Effects of soil temperature on the solute diffusion process in soils are important since subsurface temperature variation affects solute transport such as a fertilizer movement, leaching of salt, and pollutant movement to groundwater aquifers. However, the temperature dependency on the solute diffusion process in soils has been poorly understood and rarely documented. In this study, solute diffusion experiments as well as equilibrium adsorption experiments using pure kaolin clay were conducted under different temperature conditions. The experiments of K+ adsorption on kaolin clay showed more enhanced adsorption of K+ at elevated temperature likely because surface charge characteristics were affected at different temperature conditions for the kaolin clay. The temperature dependent solute diffusion showed that the solute diffusion coefficient at 40 degrees C was around two times higher than that at 6 degrees C for Cl- and K+. Overall, Arrhenius equation describing temperature dependent solute diffusion was applicable for both ions in samples at different bulk densities. At 40 degrees C, the liquid-phase impedance factor decreased, while liquid-phase pore-network tortuosity increased, suggesting changes in chemical surface activity towards the solute or pore structure changes of the clay fabric at the elevated temperature.
• 8-1-21 福島県内畑土壌における施肥カリウム動態に関する研究 その（2） 42K を用いたカラム実験（8-1 環境保全，2016年度佐賀大会）

  濱本 昌一郎, 田渕 莞士, 二瓶 直登, 平山 孝, 江口 哲也, 久保 堅司, 西村 拓

  日本土壌肥料学会講演要旨集 一般社団法人 日本土壌肥料学会 62 149 - 149 0288-5840 2016
• Transport properties and pore-network structure in variably-saturated Sphagnum peat soil

  S. Hamamoto, S. H. Dissanayaka, K. Kawamoto, O. Nagata, T. Komtatsu, P. Moldrup

  EUROPEAN JOURNAL OF SOIL SCIENCE 67 (1) 121 - 131 1351-0754 2016/01 [Refereed][Not invited]
   

  Gas and water transport in peat soil are of increasing interest because of their potentially large environmental and climatic effects under different types of land use. In this research, the water retention curve (WRC), gas diffusion coefficient (D-g) and air and water permeabilities (k(a) and k(w)) of layers in peat soil from two profiles were measured under different moisture conditions. A two-region Archie's Law (2RAL)-type model was applied successfully to the four properties; the reference point was taken at -9.8kPa of soil-water matric potential where volume shrinkage typically started to occur. For WRC in the very decomposed peat soil, the 2RAL saturation exponents (n) obtained for both the wetter (n(w)) and drier regions (n(d)) were smaller than those for the less decomposed peat. For D-g, the saturation exponent in the wetter region was larger than that in the drier one for all layers, which indicated enhanced blocking effects of water on gas diffusion in the wetter region. For the peat layers within each soil, there was a linear relation between saturation exponents in the drier region for k(a) and D-g. The larger saturation exponent of the wetter region for k(w) in peat than in sand suggests a need for specific hydraulic functions for peat soil. The 2RAL model for D-g agreed well with measured data, and performed better than existing unimodal models. To facilitate use of the 2RAL for D-g, we developed a simple predictive expression for D-g at the reference point. The pore-network tortuosity factor and equivalent pore diameter for gas transport confirmed very different pore structure and mass transport behaviour for peat soil and uniform sand.
• Pore Network Structure Analysed by Microfocus Xray-CT for Porous Media with Different Size Fractions and Particle Shape: Link to Mass Transport Parameters

  Hamamoto, S, P. Moldrup, K. Kawamoto, T. Sakaki, T. Nishimura, T. Komatsu

  Soils and Foundations 2016 [Refereed][Not invited]
  
• Geotechnical Properties of Kanto Alluvial Soils based on Geochemical Survey

  Shoichiro Hamamoto, Ken Kawamoto, Takato Takemura, Katsumi Kimura, Toshiko Komatsu, Masanobu Oda

  GSTF Journal of Geological Sciences 2 (1) 1 - 7 2015/07/01 [Refereed][Not invited]
  
• Effect of Thermal Change by Ground Source Heat Pumps on Groundwater and Geoenvironment in the Late Pleistocene Terrace Area of Tokyo, Japan

  Takato Takemura, Ayako Funabiki, Atsunori Kaneki, Yoshiharu Ito, Shoichiro Hamamoto, Takeshi Saito, Toshiko Komatsu

  ENGINEERING GEOLOGY FOR SOCIETY AND TERRITORY, VOL 5: URBAN GEOLOGY, SUSTAINABLE PLANNING AND LANDSCAPE EXPLOITATION 1201 - 1204 2015 [Refereed][Not invited]
   

  Soil and underground water pollution by waste heat in urban area is linked to the development of underground commercial facilities and subways and to the installation of ground source heat pump (GSHP) systems. In this study, we carried out laboratory tests of the dependence of dissolution elements on temperature, using boring core samples taken from the central Tokyo area in order to reduce the risks to underground water pollution by installed GSHP system. Our results demonstrate that we have to be careful not to risk contaminating shallow groundwater with hazardous elements, including marine and/or volcanic sediments, and by oxidizing the environment.
• In-situ thermal disturbance affected groundwater quality in a marine sediment aquifer (Saitama, Japan)

  Saito, T, Ueki, T, Ohkubo, S, Hamamoto, S, Kawamoto, K, Moldrup, P, Komatsu T

  Proceedings of the 3rd International Symposium on Advances in Civil and Environmental Engineering Practices for Sustainable Development なし 201 - 205 2015 [Refereed][Not invited]
  
• Simultaneous Loss of Soil Biodiversity and Functions along a Copper Contamination Gradient: When Soil Goes to Sleep

  Muhammad Naveed, Per Moldrup, Emmanuel Arthur, Martin Holmstrup, Mogens Nicolaisen, Markus Tuller, Lasantha Herath, Shoichiro Hamamoto, Ken Kawamoto, Toshiko Komatsu, Hans-Joerg Vogel, Lis Wollesen de Jonge

  SOIL SCIENCE SOCIETY OF AMERICA JOURNAL 78 (4) 1239 - 1250 0361-5995 2014/07 [Refereed][Not invited]
   

  The impact of biodiversity loss on soil functions is well established via laboratory experiments that generally consider soil biota groups in isolation from each other, a condition rarely present in field soils. As a result, our knowledge about anthropogenic-induced changes in biodiversity and associated soil functions is limited. We quantified an array of soil biological constituents (plants, earthworms, nematodes, bacteria, and fungi) to explore their interactions and to characterize their influence on various soil functions (habitat for soil organisms, air and water regulation, and recycling of nutrients and organic waste) along a legacy Cu pollution gradient. Increasing Cu concentrations had a detrimental impact on both plant growth and species richness. Belowground soil biota showed similar responses, with their sensitivity to elevated Cu concentrations decreasing in the order: earthworms > bacteria > nematodes > fungi. The observed loss of soil biota adversely affected natural soil bioturbation, aggregate formation and stabilization, and decomposition and mineralization processes and therefore resulted in compacted soil with narrow pore size distributions and overall smaller pores, restricted air and water storage and flow, and impeded C, N, and P cycling. The simultaneous evolution of soil biodiversity and functions along the Cu gradient emphasized the key role of soil life in controlling ecosystem services. Furthermore, results indicated that different soil biodiversity and functional indicators started to decline (10% loss) within a Cu concentration range of 110 to 800 mg total Cu kg(-1).
• Adsorption of Cd(II) and Pb(II) onto Humic Acid-Treated Coconut (Cocos nucifera) Husk

  B. G. N. Sewwandi, Meththika Vithanage, S. S. R. M. D. H. R. Wijesekara, M. I. M. Mowjood, Shoichiro Hamamoto, Ken Kawamoto

  JOURNAL OF HAZARDOUS TOXIC AND RADIOACTIVE WASTE 18 (2) 4014001  2153-5493 2014/04 [Refereed][Not invited]
   

  This study was conducted to characterize the adsorption of Cd2+ and Pb2+ by raw coconut husk (RCH) and humic acid-treated coconut husk (HACH). Grounded and sieved coconut husk (CH) from Sri Lanka was treated with humic acid to use as the adsorbent in laboratory experiments. Capacities of HACH and RCH for adsorption of Cd2+ and Pb2+ at different pH, ionic strengths, initial metal concentrations, and contact times between adsorbent and adsorbate were measured. The effects of binary metal solution, anions, and cations on adsorptions of Cd2+ and Pb2+ by treated and nontreated CH in batch experiments were also examined. The surface characteristics of HACH and RCH were investigated by scanning electron micrography (SEM), X-ray energy dispersion analysis (EDAX), methylene blue (MB), and the Brunauer, Emmett, and Teller (BET) methods to explain the results. Results showed that adsorption of Cd2+ and Pb2+ ions by HACH was independent of pH and ionic strength. The maximum adsorption capacities of Cd2+ and Pb2+ of HACH were 47.28 and 66.26 mg g-1 and were greater than 24.24 and 21.21 mg g-1 for RCH. The adsorption of both Cd2+ and Pb2+ onto HACH was a chemical sorption, and Pb2+ adsorption needed a longer reaction time than Cd2+ adsorption. The adsorption reaction rates of Cd2+ and Pb2+ of HACH were 0.056 and 3.17 mg g-1 min-1. Some anions and cations affected the adsorption of Cd2+ and Pb2+ onto HACH. Based on the results from adsorption tests under different conditions, RCH and HACH are effective for individual removal of Cd2+ and Pb2+ from aqueous solutions. However, humic acid treatment effectively removes metal ions from single metal solutions, although the removal of metal ions in the presence of coexisting ions and other anions and cations could be retarded. © 2014 American Society of Civil Engineers.
• Thermal properties of boring core samples from the Kanto area, Japan: Development of predictive models for thermal conductivity and diffusivity

  Takeshi Saito, Shoichiro Hamamoto, Ei Ei Mon, Takato Takemura, Hirotaka Saito, Toshiko Komatsu, Per Moldrup

  SOILS AND FOUNDATIONS 54 (2) 116 - 125 0038-0806 2014/04 [Refereed][Not invited]
   

  The subsurface of the Earth is facing evermore thermal impact due to global warming, urban heat islands, and the widespread use of ground source heat pump (GSHP) systems. This potentially causes changes in its physical, mechanical, microbiological, and chemical properties, and in the subsurface water quality. To predict and evaluate this thermal impact (or thermal pollution), a better understanding and improved models for the thermal properties governing heat transport in subsurface sediments are needed. Also, data acquisition in high spatial resolution for the thermal properties and basic physical properties of the subsurface sediments are essential. In this study, the main thermal properties (the thermal conductivity, heat capacity, and thermal diffusivity) together with the basic physical properties (the soil texture, water content, and dry bulk density) were measured on boring core samples representing depths from 0 to 50 or 80 in, at three study sites in the Kanto area of Japan. Based on the measured data, models for thermal conductivity as functions of gravimetric water content, dry bulk density, and volumetric sand content were developed. The new models performed markedly better than presently available models from the literature and, in combination with a modified de Vries type model for heat capacity, the resulting model for thermal diffusivity was capable of describing the measured data well The usefulness of the newly developed models were validated and illustrated by using data from a two-day thermal response test (TRT) performed at one of the three study sites. The new predictive models for the thermal properties used in a numerical heat transport simulation accurately predicted subsurface (5-50 m) temperature changes during the TRT. (C) 2014 The Japanese Geotechnical Society. Production and hosting by Elsevier B.V. All rights reserved.
• Characterization of time-dependent contact angles for oleic acid mixed sands with different particle size fractions

  Wijewardana, Y. N. S., Kawamoto, K., Komatsu, T., Hamamoto, S., Subedi, S., Moldrup, P.

  Unsaturated Soils: Research & Applications, Vols 1 and 2 2014
• Effects of subsurface temperature increase on groundwater quality in alluvial sediment of Arakawa Low-land, Japan

  Ueki, T, T. Saito, S. Hamamoto, I. Sakaguchi, K. Arai, K. Kawamoto, P. Moldrup, T. Komatsu

  Proceedings of the 5th International Conference on Sustainable Built Environment 16 - 21 2014 [Refereed][Not invited]
  
• 地球温暖化がもたらす地盤の環境変化と災害 6. 地温変化が地盤環境に及ぼす影響と評価

  竹村貴人, 濱本昌一郎, 大西純一, 中尾有利子, 伊東芳夫

  地盤工学会ジャーナル 62 (2) 42 - 49 1882-7276 2014 [Refereed][Not invited]
  
• 熱応答試験における熱交換過程の数値解析

  斎藤広隆, 斎藤健志, 向後雄二, 濱本昌一郎, P. Moldrup, 小松登志子

  土壌の物理性 128 3 - 5 2014 [Refereed][Not invited]
  
• Characterization of alkali-soluble polysaccharides in deep subsoil layers

  Toshihisa Kotake, Shoichiro Hamamoto, Takeshi Saito, Junichi Ohnishi, Toshiko Komatsu, Yoichi Tsumuraya

  SOIL SCIENCE AND PLANT NUTRITION 59 (6) 871 - 876 0038-0768 2013/12 [Refereed][Not invited]
   

  Plant cell wall polysaccharides undergo a slower degradation process in deep subsoil layers than in topsoil. Through the identification of organic compounds in subsoil, we may gain an understanding of this degradation process. In the present study, we extracted alkali-soluble polysaccharides from subsoil bore samples at depths of 5, 18, 29, 35 and 40-43m, and performed sugar composition and sugar linkage analyses. Based on the results, we suggest that cellulose, arabinoxylan, mannan and pectic polysaccharides derived from plant cell walls and -1,3-glucan and/or -1,3:1,6-glucan from fungal cell walls exist in deep subsoil layers.
• Structure-Dependent Water-Induced Linear Reduction Model for Predicting Gas Diffusivity and Tortuosity in Repacked and Intact Soil

  Per Moldrup, T. K. K. Chamindu Deepagoda, Shoichiro Hamamoto, Toshiko Komatsu, Ken Kawamoto, Dennis E. Rolston, Lis Wollesen de Jonge

  VADOSE ZONE JOURNAL 12 (3) 1539-1663 2013/08 [Refereed][Not invited]
   

  The soil-gas diffusion is a primary driver of transport, reactions, emissions, and uptake of vadose zone gases, including oxygen, greenhouse gases, fumigants, and spilled volatile organics. The soil-gas diffusion coefficient, D-p, depends not only on soil moisture content, texture, and compaction but also on the local-scale variability of these. Different predictive models have been developed to estimate D-p in intact and repacked soil, but clear guidelines for model choice at a given soil state are lacking. In this study, the water-induced linear reduction (WLR) model for repacked soil is made adaptive for different soil structure conditions (repacked, intact) by introducing a media complexity factor (C-m) in the dry media term of the model. With C-m = 1, the new structure-dependent WLR (SWLR) model accurately predicted soil-gas diffusivity (D-p/D-o, where D-o is the gas diffusion coefficient in free air) in repacked soils containing between 0 and 54% clay. With C-m = 2.1, the SWLR model on average gave excellent predictions for 290 intact soils, performing well across soil depths, textures, and compactions (dry bulk densities). The SWLR model generally outperformed similar, simple D-p/D-o models also depending solely on total and air-filled porosity. With C-m = 3, the SWLR performed well as a lower-limit D-p/D-o model, which is useful in terms of predicting critical air-filled porosity for adequate soil aeration. Because the SWLR model distinguishes between and well represents both repacked and intact soil conditions, this model is recommended for use in simulations of gas diffusion and fate in the soil vadose zone, for example, as a key element in developing more accurate climate change models.
• Temperature Effects on Geotechnical Properties of Kaolin Clay: Simultaneous Measurements of Consolidation Characteristics, Shear Stiffness and Permeability Using a Modified Oedometer

  Ei Ei Mon, Shoichiro Hamamoto, Ken Kawamoto Kawamoto, Toshiko Komatsu, Per Møldrup

  GSTF Journal of Geological Sciences (JGS) - Volume 1 Number 1 1 (1) 1 - 10 2013/04 [Refereed][Not invited]
  
• Modeling Air Permeability in Variably Saturated Soil from Two Natural Clay Gradients

  Chamindu T. K. K. Deepagoda, Emmanuel Arthur, Per Moldrup, Shoichiro Hamamoto, Ken Kawamoto, Toshiko Komatsu, Lis Wollesen de Jonge

  SOIL SCIENCE SOCIETY OF AMERICA JOURNAL 77 (2) 362 - 371 0361-5995 2013/03 [Refereed][Not invited]
   

  Understanding soil-gas phase properties and processes is important for finding solutions to critical environmental problems such as greenhouse gas emissions and transport of gaseous-phase contaminants in soils. Soil-air permeability, k(a) (mu m(2)), is the key parameter governing advective gas movement in soil and is controlled by soil physical characteristics representing soil texture and structure. Models predicting k(a) as a function of air-filled porosity (epsilon) often use a reference-point measurement, for example, k(a), 1000 at epsilon(1000) (where the measurement is done at a suction of -1000 cm H2O). Using k(a) measurements from two Danish arable fields, each located on natural clay gradients, this study presents a pore tortuosity-disconnectivity analysis to characterize the soil-gas phase. The main objective of this study is to investigate the effect of soil-moisture condition, clay content, and other potential drivers of soil texture and structure on soil-gas phase characteristics based on a k(a)-based pore tortuosity parameter, X-a [= log(k(a)/k(a,1000))/log(epsilon/epsilon(,1000))]. Results showed that X-a did not vary significantly with soil matric potential (in the range of -10 to -1000 cm H2O), but the average X-a across moisture conditions showed a strong linear relation (R-2 = 0.74) to clay content. The X-a, further showed promising relations to specific surface area, Rosin-Rammler particle size distribution indices, alpha and beta (representing characteristic particle size and degree of sorting, respectively), and the Campbell water retention parameter, b. Considering clay as a main driver of soil-gas phase characteristics, we developed expressions linking clay content and k(a,1000) at epsilon(1000) and discussed the effect of clay content on general k(a)-epsilon behavior.
• Correlating Gas Transport Parameters and X-Ray Computed Tomography Measurements in Porous Media

  Muhammad Naveed, Shoichiro Hamamoto, Ken Kawamoto, Toshihiro Sakaki, Manabu Takahashi, Toshiko Komatsu, Per Moldrup, Mathieu Lamande, Dorthe Wildenschild, Masa Prodanovic, Lis Wollesen de Jonge

  SOIL SCIENCE 178 (2) 60 - 68 0038-075X 2013/02 [Refereed][Not invited]
   

  Gas transport parameters and X-ray computed tomography (CT) measurements in porous medium under controlled and identical conditions provide a useful methodology for studying the relationships among them, ultimately leading to a better understanding of subsurface gaseous transport and other soil physical processes. The objective of this study was to characterize the relationships between gas transport parameters and soil-pore geometry revealed by X-ray CT. Sands of different shapes with a mean particle diameter (d(50)) ranging from 0.19 to 1.51 mm were used as porous media under both air-dried and partially saturated conditions. Gas transport parameters including gas dispersivity (alpha), diffusivity (D-P/D-0), and permeability (k(a)) were measured using a unified measurement system (UMS). The 3DMA-Rock computational package was used for analysis of three-dimensional CT data. A strong linear relationship was found between alpha and tortuosity calculated from gas transport parameters (T-UMS = root epsilon.D-O/D-P), indicating that gas dispersivity has a linear and inverse relationship with gas diffusivity. A linear relationship was also found between k(a) and d(50)/T-UMS(2), indicating a strong dependency of k(a) on mean particle size and direct correlation with gas diffusivity. Tortuosity (T-MFX) and equivalent pore diameter (d(eq.MFX)) analyzed from microfocus X-ray CT increased linearly with increasing d(50) for both Granusil and Accusand and further showing no effect of particle shape. The T-UMS values showed reasonably good agreement with T-MFX values. The k(a) showed a strong relationship when plotted against d(eq.MFX)/T-MFX(2), indicating its strong dependency on pore size distribution and tortuosity of pore space.
• Effects of Sedimentary Depositional Environment on the Dynamic Mechanical Properties of Holocene Clay in the Southern Kanto Plain, Central Japan

  Takato Takemura, Masanobu Oda, Shoichiro Hamamoto, Ken Kawamoto, Tomoya Akama, Hidemichi Tai, Katsumi Kimura

  JOURNAL OF GEOGRAPHY-CHIGAKU ZASSHI 公益社団法人 東京地学協会 122 (3) 472 - 492 0022-135X 2013 [Not refereed]
   

  The effects of earthquakes in the Kanto district are strongly related to the three-dimensional distribution of the soil mechanical properties of Chuseki-so, which is the name given to incisedvalley fills from the Late Pleistocene to the Holocene. To characterize the effects of the sedimentary depositional environment and sedimentary process of Chuseki-so on soil mechanical properties, PS logging test, physical-chemical test, consolidation test, cyclic tri-axial test, and bender element test were conducted on an undisturbed core sample. Based on the test results, we propose a method to estimate the elastic shear modulus of clay soil from conventional soil properties, and discuss the relationship between the sedimentary process of Chuseki-so and the threedimensional distribution of soil mechanical properties. Through our investigation, we derived the following conclusions: (1) The delta front and inner bay deposits of the Kasukabe core in the Nakagawa Lowland comprise very soft clay and have a high water content and liquidity index; these characteristics are related to the sedimentary depositional environment such as water depth and salinity (ratio of marine diatoms in the sediment). (2) The proposed method can be used to estimate elastic shear moduli on the basis of water content, depth, and locality parameter; in particular, it can be used to evaluate very soft clay, the N value of which is less than 1, on the basis of water content, an easily measurable property. (3) Both bender element and PS logging tests show similar S-wave velocities, and elastic shear moduli measured using the respective tests, G0(BF) and G(0)(PS), were also similar; therefore, elastic shear moduli can be determined through measurements using these two tests or estimations based on water content. (4) The method to determine the elastic shear modulus, G(0)(TR), which is obtained using a cyclic test, is pro posed based on the H-D model; G(0)(TR) btained correlates well with G(0)(BE), even if though it is obtained by a different method. The proposed method can be used to determine elastic shear moduli with great accurac.
• Effect of temperature change on shear modulus of kaolin clay in the secondary compression stage

  Mon, E. E, S. Hamamoto, K. Kawamoto, M. Oda, T. Komatsu

  18th Southeast Asian Geotechnical & Inaugural AGSSEA Conference 29 - 31 2013 [Refereed][Not invited]
  
• 環境地質学的なアプローチによる地温上昇に伴う地下環境の影響評価

  竹村貴人, 船引彩子, 中尾有利子, 濱本昌一郎

  第10回環境地盤工学シンポジウム発表論文集 19 - 22 2013 [Refereed][Not invited]
  
• 関東南部地下帯水層土壌に含まれる真正細菌叢の網羅的解析

  Azad, M, 是枝晋, 濱本昌一郎, 大西純一, 小松登志子

  第10回環境地盤工学シンポジウム発表論文集 23 - 26 2013 [Refereed][Not invited]
  
• 関東ローム層における地温上昇に伴う溶出元素の特徴に関する実験的研究

  金木厚憲, 竹村貴人, 市村智, 船引彩子, 濱本昌一郎, 斎藤健志

  第10回環境地盤工学シンポジウム発表論文集 10th 15 - 18 2013 [Refereed][Not invited]
  
• 地盤への熱負荷が地温・地下水質に与える影響,環境地質学的なアプローチによる地温上昇が与える地下環境への影響評価

  濱本昌一郎, 斎藤健志, 植木崇, 立石佳祐, 松倉重雄, 小松登志子

  第10回環境地盤工学シンポジウム発表論文集 10th 11 - 14 2013 [Refereed][Not invited]
  
• Thermal properties of sands at variably-saturated condition: Effects of particle size and shape, and quartz content

  KAMOSHIDA Takahisa, HAMAMOTO Shoichiro, KAWAMOTO Ken, SAKAKI Toshihiro, KOMATSU Toshiko

  Journal of the Japanese Society of Soil Physics 土壌物理学会 11 11 - 16 0387-6012 2013 [Refereed][Not invited]
   

  Thermal properties of sands with different par-ticle size and shape were measured. All sands showed the similar trend for the change in heat capacity, increas-ing with increasing in water content (θ).The gradient of the thermal conductivity (λ) to θ under the dry region (θ < 0.05 〜0.10) increased with increasing particle size for sands with rough shape, indicating an increase in con-tact points per soil particle highly enhanced thermal con-duction. Oppositely, for the wet region (θ > 0.05 〜0.10), the gradient of λ to 0 were similar for sands with different particle size. Equations of λ at completely dry condition and water saturation were derived from obtained relation-ships between quartz content and Z in this study. By in-serting these equations, existing models for thermal con-ductivity were modified, which markedly improved model performances.
• Effects of Sedimentary Depositional Environment on the Dynamic Mechanical Properties of Holocene Clay in the Southern Kanto Plain, Central Japan

  TAKEMURA Takato, ODA Masanobu, HAMAMOTO Shoichiro, KAWAMOTO Ken, AKAMA Tomoya, TAI Hidemichi, KIMURA Katsumi

  J. Geogr. Tokyo Geographical Society 122 (3) 472 - 492 0022-135X 2013 [Refereed][Not invited]
   

  The effects of earthquakes in the Kanto district are strongly related to the three-dimensional distribution of the soil mechanical properties of Chuseki-so, which is the name given to incised-valley fills from the Late Pleistocene to the Holocene. To characterize the effects of the sedimentary depositional environment and sedimentary process of Chuseki-so on soil mechanical properties, PS logging test, physical-chemical test, consolidation test, cyclic tri-axial test, and bender element test were conducted on an undisturbed core sample. Based on the test results, we propose a method to estimate the elastic shear modulus of clay soil from conventional soil properties, and discuss the relationship between the sedimentary process of Chuseki-so and the three-dimensional distribution of soil mechanical properties. Through our investigation, we derived the following conclusions: (1) The delta front and inner bay deposits of the Kasukabe core in the Nakagawa Lowland comprise very soft clay and have a high water content and liquidity index; these characteristics are related to the sedimentary depositional environment such as water depth and salinity (ratio of marine diatoms in the sediment). (2) The proposed method can be used to estimate elastic shear moduli on the basis of water content, depth, and locality parameter; in particular, it can be used to evaluate very soft clay, the N value of which is less than 1, on the basis of water content, an easily measurable property. (3) Both bender element and PS logging tests show similar S-wave velocities, and elastic shear moduli measured using the respective tests, G₀^BE and G₀^PS, were also similar; therefore, elastic shear moduli can be determined through measurements using these two tests or estimations based on water content. (4) The method to determine the elastic shear modulus, G₀^TR, which is obtained using a cyclic test, is proposed based on the H-D model; G₀^TR btained correlates well with G₀^BE, even if though it is obtained by a different method. The proposed method can be used to determine elastic shear moduli with great accurac.
• EFFECT OF DRYING AND WETTING PROCESSES ON AIR PERMEABILITY OF UNSATURATED SAND

  SASANUMA Kumi, HAMAMOTO Shoichiro, KAWAMOTO Ken, SAKAKI Toshihiro, KOMATSU Toshiko

  Journal of Japan Society of Civil Engineers, Ser. C (Geosphere Engineering) 公益社団法人 土木学会 69 (3) 378 - 385 2013 [Refereed][Not invited]
   

  Understanding the relationship among water saturation, water matric potential, and air permeability is important for accurately simulating the behavior of toxic gases at the polluted site and optimizing remediation technologies. In this study, air permeability (k_a) was measured on sands with different particle sizes and shapes during drying and wetting cycles. The hysteresis in soil-water retention highly affected gas transport, showing higher k_a for the wetting processes than for the drying processes at the same air content for all sand samples. This suggests that the existence of more continuous air-filled pore networks for the wetting processes enhanced advective gas transport. A power-law type k_a model was applied to the measured data, demonstrating a clear relation between the pore network tortuosity factor in the k_a model and model parameters for describing water retention characteristics. In addition, it is indicated that for sands with rough particle shape the continuity in larger-pore network is obstructed by the soil water filled in smaller pores as compared to sands with round shape.
• Maxwell's Law Based Models for Liquid and Gas Phase Diffusivities in Variably-Saturated Soil

  Shoichiro Hamamoto, Per Moldrup, Ken Kawamoto, Toshiko Komatsu

  SOIL SCIENCE SOCIETY OF AMERICA JOURNAL 76 (5) 1509 - 1517 0361-5995 2012/09 [Refereed][Not invited]
   

  The gas diffusion coefficient (D-s,D-g) and solute diffusion coefficient (D-s,D-l) and their dependencies on fluid content (kappa) (equal to soil-air content theta for D-s,D-g and soil-water content epsilon for D-s,D-l) are controlling factors for gas and solute transport in variably saturated soils. In this study, we propose unified, predictive models for D-s,D-g(epsilon) and D-s,D-l(theta) based on modifying and extending the classical Maxwell model at fluid saturation with a fluid-induced reduction term including a percolation threshold (epsilon(th) for D-s,D-g and theta(th) for D-s,D-l). Different percolation threshold terms adopted from recent studies for gas (D-s,D-g) and solute (D-s,D-l) diffusion were applied. For gas diffusion, epsilon(th) was a function of bulk density (total porosity), while for solute diffusion theta(th) was best described by volumetric content of finer soil particles (clay and organic matter), FINESvol. The resulting LIquid and GAs diffusivity and tortuosity (LIGA) models were tested against D-s,D-g and D-s,D-l data for differently-textured soils and performed well against the measured data across soil types. A sensitivity analysis using the new Maxwell's Law based LIGA models implied that the liquid phase but not the gaseous-phase tortuosity was controlled by soil type. The analyses also suggested very different pathways and fluid-phase connectivity for gas and solute diffusion in unsaturated soil. In conclusion, the commonly applied strategy of using the same, soil-type-independent model for gas and solute diffusivity in analytical and numerical models for chemical transport and fate in variably-saturated soils appears invalid, except for highly sandy soils. The unified LIGA model with differing percolation thresholds for diffusion in the liquid and gaseous phases solves this problem.
• Gas Dispersion in Granular Porous Media under Air-Dry and Wet Conditions

  Muhammad Naveed, Shoichiro Hamamoto, Ken Kawamoto, Toshihiro Sakaki, Manabu Takahashi, Toshiko Komatsu, Lis Wollesen de Jonge, Mathieu Lamande, Per Moldrup

  SOIL SCIENCE SOCIETY OF AMERICA JOURNAL 76 (3) 845 - 852 0361-5995 2012/05 [Refereed][Not invited]
   

  Subsurface gaseous-phase transport is governed by three gas transport parameters: the air permeability coefficient (k(a)), gas diffusion coefficient (D-p), and gas dispersion coefficient (D-H). Among these, D-H is the least understood due to hitherto limited research into the relationship between gas dispersion and soil physical characteristics. In this study, a series of advection dispersion experiments was performed on granular porous media to identify the effects of soil column dimensions (length and diameter), particle size and shape, dry bulk density, and moisture content on the magnitude of gas dispersion. Glass beads and various sands of different shapes (angular and rounded) with mean particle diameters (d(50)) ranging from 0.19 to 1.51 mm at both air-dry and variable moisture contents were used as granular porous media. Gas dispersion coefficients and gas dispersivities alpha = D-H/v, where v is the pore-gas velocity) were determined by fitting the advection-dispersion equation to the measured breakthrough curves. For all test conditions, D-H increased linearly with v. The test results showed that neither soil column length nor diameter had significant effect on gas dispersivity. Under air-dry conditions, higher gas dispersivities were observed for media with wider particle size distribution and higher dry bulk density. The minor effect of particle shape on gas dispersivity was found under both air-dry and wet conditions. Under wet conditions, the variations in gas dispersivity were mainly controlled by the air-filled porosity. An empirical model was also proposed for the prediction of gas dispersivity in granular, unsaturated porous media.
• Thermal Properties of Peaty Soils: Effects of Liquid-Phase Impedance Factor and Shrinkage

  Shiromi Himalika Dissanayaka, Shoichiro Hamamoto, Ken Kawamoto, Toshiko Komatsu, Per Moldrup

  VADOSE ZONE JOURNAL 11 (1) 1539-1663 2012/02 [Refereed][Not invited]
   

  Soil thermal conductivity (lambda) and heat capacity (C) control heat transport and the thermal environment for biogeophysical processes in the vadose zone. Accurate lambda and C predictions for peaty soils with high organic contents are particularly important for assessing emissions of greenhouse gases formed during microbial activity in wetlands. In this study, we measured the lambda and C at different soil-water matric potentials on undisturbed samples for three peaty soil profiles at the Hokkaido Bibai marsh in Japan, representing a total of 10 different soil horizons. The thermal properties under air-dried conditions, lambda(dry) and C-dry, were measured separately at changing volumetric solids contents (sigma). For each sample, volume shrinkage was observed to varying degrees during the drying process. Measured lambda and C increased linearly with increasing volumetric water content (theta). Applying the concept of a three-phase mixing model and incorporating the lambda-theta or C-theta and the lambda(dry)-sigma or C-dry-sigma relations, predictive lambda and C models were developed as functions of sigma and theta. The new mixing model is represented by lambda = lambda(dry) + f(lambda)theta lambda(w) and C = C-dry + f(C)theta C-w, where lambda(w) and C-w are the thermal conductivity and heat capacity of water, respectively, and f is an impedance factor that takes into account the liquid-phase tortuosity. The new mixing model predicted literature lambda-theta data on peaty and highly organic soils under variable saturation well. The probable ranges of lambda and C under variable saturation were proposed based on the sensitivity analysis.
• Unified measurement system with suction control for measuring hysteresis in soil-gas transport parameters

  Md Abdur Rouf, Shoichiro Hamamoto, Ken Kawamoto, Toshihiro Sakaki, Toshiko Komatsu, Per Moldrup

  WATER RESOURCES RESEARCH 48 W02506  0043-1397 2012/02 [Refereed][Not invited]
   

  A unified measurement system with suction control (UMS_SC) was developed for measuring soil water characteristics curves (SWCC) and gas transport parameters under alternating drying and wetting cycles. The new system consists of a diffusion chamber, sample ring, porous plate, tensiometer, moisture sensor, oxygen electrodes, and air pressure gauges. The SWCC and gas transport parameters [gas diffusion coefficient (D-p) and air permeability (k(a))] for two different porous materials, Toyoura sand and granulated slag, were simultaneously measured under drying and wetting cycles. The SWCC and gas transport parameters measured by UMS_SC were consistent with recent models and independently measured data on exactly the same materials using standard experimental setups from literature. For an applied water suction head of less than 50 cm and corresponding water saturation of around 0.3-0.5, the UMS_SC data documented hysteretic (nonsingular) behavior in both measured Dp and ka under repeated drying and wetting cycles. The hysteretic behavior was insignificant for water and air contents but large for both gas transport parameters when applying suction, and hysteretic effects were larger for air permeability than for gas diffusivity. Additionally, hysteresis in the percolation threshold (soil-air content where gas transport ceases due to interconnected water-filled pores) for both gas diffusion and air permeability was insignificant for both materials. These findings should be taken into account when developing models for diffusive and convective gas transport and their parameters in variably saturated porous media.
• Diffusivity of rocks: Gas diffusion measurements and correlation to porosity and pore size distribution

  Sheng Peng, Qinhong Hu, Shoichiro Hamamoto

  WATER RESOURCES RESEARCH 48 W02507  0043-1397 2012/02 [Refereed][Not invited]
   

  Diffusivity was measured for 12 rock and construction material samples using a diffusion chamber method with oxygen as the tracer gas. Several steps were implemented to minimize leakage between the sample and the core holder, and rigorous tests were performed to evaluate and correct the overall leakage of the diffusion apparatus. This method was proven capable of rapidly measuring the diffusion coefficient for consolidated samples having dimensionless diffusivity values greater than 4.7 x 10(-4) in a relative short duration (hours to 1 day). Gas diffusion measurements were also conducted for 11 repacked sediments and sands. Our results are consistent with literature data from liquid tracer through-diffusion methods; the diffusivity versus porosity relationship for our data can be described by Archie's law. The m value in Archie's law was found to be correlated to pore size: the finer the pore size is, the larger the m value is. A linear regression equation can describe the change of m with ln d(50) (the volumetric mean pore diameter) for most rocks with d(50) < 1.3 mu m, while the outliers can be correlated to narrower pore size distribution.
• Organic Matter Fraction Dependent Model for Predicting the Gas Diffusion Coefficient in Variably Saturated Soils

  Shoichiro Hamamoto, Per Moldrup, Ken Kawamoto, Toshiko Komatsu

  VADOSE ZONE JOURNAL 11 (1) 1539-1663 2012/02 [Refereed][Not invited]
   

  Gas diffusion is a dominant transport mechanism for climate and regulated gases in the vadose zone. Soil-gas diffusion is governed by the gas diffusion coefficient (D-p, m(2) s(-1)) which is highly dependent on soil texture, such as sand, silt, clay, and organic mater contents, as well as soil physical properties such as soil-air content (epsilon, m(3) m(-3)) or total porosity (Phi, m(3) m(-3)). Soil organic matter is a key contributor to the formation of the soil pore structure (i.e., total porosity and air-filled pore tortuosity), and it highly affects D-p behavior under variably saturated conditions. In this study, based on numerous D-p data sets across soil types including sands, loamy clay soils, volcanic ash soils, and organic soils, predictive D-p models incorporating a percolation threshold (epsilon th, m(3) m(-3)) and pore tortuosity factor (X') are proposed. The observed relations between either epsilon(th) or X' and either Phi or volumetric organic matter fraction (OMF, m(3) m(-3)) were embedded in the proposed D-p model. The proposed D-p models, coupled with predictive epsilon(th) and OMF models, performed well against the measured D-p data across soil types. Finally, a sensitivity analysis of the OMF in relation to the D-p and pore-network tortuosity (T) showed a reduction in D-p and increase in T with increasing OMF under the same epsilon conditions.
• Gas and heat transport in variably-compacted landfill cover at variably-saturated condition

  Hamamoto, S, K. Kawamoto, T. Komatsu

  Proceedings of international symposium on advances in civil and environmental engineering practices for sustainable development, ACEPS-2012 48 - 54 2012 [Refereed][Not invited]
  
• Characterization of geotechnical properties as affected by sediment environment in Kanto lowland clays in Japan

  Tsuboi, H, Y. Yanase, S. Hamamoto, K. Kawamoto, T. Takemura, M. Oda

  Proceedings of international symposium on advances in civil and environmental engineering practices for sustainable development, ACEPS-2012 71 - 78 2012 [Refereed][Not invited]
  
• Heat and gas transport characteristics in differently-decomposed peaty soils at variably-saturated conditions

  Dissanayaka, S. H, S. Hamamoto, K. Kawamoto, T. Komatsu

  Proceedings of international symposium on advances in civil and environmental engineering practices for sustainable development, ACEPS-2012 79 - 85 2012 [Refereed][Not invited]
  
• Developments of unified predictive models for solute and gas diffusivities in variably-saturated soil

  Hamamoto, S

  Conference Proceedings of The Seventh Asian Young Geotechnical Engineers Conference 239 - 244 2012 [Refereed][Not invited]
  
• Compressibility of Japanese landfilled/buried waste samples: Measurement of compaction curves and consolidation test for compacted waste samples at different compaction levels

  Nandika, H.L.D, S. Hamamoto, T. Koide, K. Kawamoto, K. Endo

  In Proc. 2nd International Conference on Sustainable Built Environment 27 - 31 2012 [Refereed][Not invited]
  
• Locally available expansive soils as a liner material for municipal landfills

  Wanigarathna, D, L.C. Kurukulasuriya, S. Hamamoto, K. Kawamoto

  In Proc. 2nd International Conference on Sustainable Built Environment 24 - 27 2012 [Refereed][Not invited]
  
• The pH Dependency of 2,4-Dichlorophenoxyacetic Acid Adsorption and Desorption in Andosol and Kaolinite

  Ei Ei Mon, Anu Sharma, Ken Kawamoto, Shoichiro Hamamoto, Toshiko Komatsu, Syuntaro Hiradate, Per Moldrup

  SOIL SCIENCE 177 (1) 12 - 21 0038-075X 2012/01 [Refereed][Not invited]
   

  Batch adsorption and consecutive desorption experiments were performed under different pH conditions to assess the pH dependency of 2,4-dichlorophenoxyacetic acid (2,4-D) adsorption and desorption in Andosol (having pH-dependent surface charge characteristics) and kaolinite. The adsorption-desorption isotherms for both Andosol and kaolinite were well fitted by the Freundlich isotherm model. Adsorption of 2,4-D onto Andosol increased markedly with decreasing pH and was higher than for kaolinite under the same pH condition. Hysteresis, expressing the nonsingularity of the desorption compared with the adsorption isotherm, was found at all concentrations and each pH for both Andosol and kaolinite. For Andosol, the fitted Freundlich parameters for desorption, K-f,K-d and n(d), showed a negative, linear and a positive, exponential relationship, respectively, with pH. Higher hysteresis index (omega), expressing the degree of partial irreversibility of 2,4-D adsorption, was obtained under lower pH, indicating that less adsorbed 2,4-D was released back from the Andosol under acidic condition. The effect of pH on 2,4-D desorption from kaolinite was less pronounced as compared with Andosol. Combining the measured data in this study with previously reported data on 2,4-D adsorption-desorption in several types of soil including Andosols, the possible mobility of adsorbed 2,4-D in soil was evaluated. Results show that adsorbed 2,4-D in soils exhibiting a total adsorption percentage of less than 55% of the applied pesticide typically exhibited a greater potential to be mobile in the soil-water system. Opposite, a total adsorption percentage greater than 55% implied higher residual adsorption and a prolonged existence of adsorbed 2,4-D in the soils.
• Ground Source Heat Pump and Geo-environment

  SAITO Hirotaka, HAMAMOTO Shoichiro, KOMATSU Toshiko

  JOURNAL of the JAPANESE SOCIETY of AGRICULTURAL MACHINERY 農業食料工学会 74 (1) 1 - 6 0285-2543 2012 [Refereed][Not invited]
   

  type:論文 埼玉大学を中心とする研究グループの中心メンバーとして,科学技術振興機構の戦略的創造推進事業(CREST)平成22年度採択課題「地圏熱エネルギー利用を考慮した地下水管理手法の開発(代表・小松登志子)」の中で,地中熱利用に伴う地中の局所的な熱負荷が地中(地下水を含む)における物質・熱循環および微生物動態に及ぼす影響を把握するための環境影響評価ツールの開発と,それに基づいた高効率な地中熱利用システムを含む持続的で高度な地下水利用・管理システム構築のための研究を実施している。ここでは、上記研究課題の中で,地中熱環境かく乱による環境影響を評価するための原位置実証試験について紹介する。また,環境影響評価ツール開発のために不可欠な地中温度予測について,地中熱移動基礎方程式を示し,その適用例を紹介する。 identifier:830118 identifier:ZZ00015065
• Gas Dispersion in Granular Porous Media as Affected by Texture, Particle Shape, Density, and Moisture Content.

  Naveed, M, S. Hamamoto, K. Kawamoto, T. Sakaki, M. Takahashi, T. Komatsu, P. Moldrup, L. W. de Jonge

  Soil Sci. Soc. Am. J. 76 845 - 852 2012 [Refereed][Not invited]
  
• Effects of dry bulk density and particle size fraction on gas transport parameters in variably saturated landfill cover soil

  Praneeth Wickramarachchi, Ken Kawamoto, Shoichiro Hamamoto, Masanao Nagamori, Per Moldrup, Toshiko Komatsu

  WASTE MANAGEMENT 31 (12) 2464 - 2472 0956-053X 2011/12 [Refereed][Not invited]
   

  Landfill sites are emerging in climate change scenarios as a significant source of greenhouse gases. The compacted final soil cover at landfill sites plays a vital role for the emission, fate and transport of landfill gases. This study investigated the effects of dry bulk density, rho(b), and particle size fraction on the main soil-gas transport parameters - soil-gas diffusivity (D-p/D-o, ratio of gas diffusion coefficients in soil and free air) and air permeability (k(a)) - under variably-saturated moisture conditions. Soil samples were prepared by three different compaction methods (Standard and Modified Proctor compaction, and hand compaction) with resulting rho(b) values ranging from 1.40 to 2.10 g cm(-3). Results showed that D-p and k(p) values for the '+gravel' fraction (<35 mm) became larger than for the '-gravel' fraction (<2 mm) under variably-saturated conditions for a given soil-air content (epsilon), likely due to enhanced gas diffusion and advection through less tortuous, large-pore networks. The effect of dry bulk density on D-p, and k(a) was most pronounced for the '+gravel' fraction. Normalized ratios were introduced for all soil-gas parameters: (i) for gas diffusivity D-p/D-f, the ratio of measured D-p to D-p in total porosity (f), (ii) for air permeability k(a)/k(a,pF4.1), the ratio of measured k(a) to k(a), at 1235 kPa matric potential (=pF 4.1), and (iii) for soil-air content, the ratio of soil-air content (epsilon) to total porosity (f) (air saturation). Based on the normalized parameters, predictive power-law models for D-p(epsilon/f) and k(a) (epsilon/f) models were developed based on a single parameter (water blockage factor M for D-p and P for k(a)). The water blockage factors, M and P. were found to be linearly correlated to rho(b) values, and the effects of dry bulk density on D-p and k(a) for both '+gravel' and '-gravel' fractions were well accounted for by the new models. (C) 2011 Elsevier Ltd. All rights reserved.
• Gas Transport Parameters for Compacted Reddish-Brown Soil in Sri Lankan Landfill Final Cover

  Praneeth Wickramarachchi, Kaushalya Ranasinghe, Shoichiro Hamamoto, Ken Kawamoto, Udeni P. Nawagamuwa, Per Moldrup, Toshiko Komatsu

  JOURNAL OF HAZARDOUS TOXIC AND RADIOACTIVE WASTE 15 (4) 285 - 295 2153-5493 2011/10 [Refereed][Not invited]
   

  Gas exchange through the compacted final cover soil at landfill sites plays a vital role for emission, fate, and transport of toxic landfill gases. This study involved measuring the soil-gas diffusivity (Dp/Do, the ratio of gas diffusion coefficients in soil and free air) and air permeability (ka) for differently compacted soil samples (reddish-brown soil) from the final cover at the Maharagama landfill in Sri Lanka. The samples were prepared by either standard Proctor compaction or hand compaction to dry bulk densities of 1.60-1.94 g cm-3. Existing and modified models for predicting Dp/Do and ka were tested against the measured data. The simple, single-parameter Buckingham model predicted measured Dp/Do values across compaction levels equally well or better than a dry bulk density (DBD) dependent model and a soil-water retention (SWR) dependent model. The measured ka values for differently compacted samples were highly affected by the compaction level and the sample moisture preparation method. Also, for air permeability, a single-parameter Buckingham-type ka model was most accurate in predicting ka in the differently compacted soil samples. Equivalent air-filled pore diameters (the effective diameter of the drained pores active in leading air through the sample) for gas flow, deq, were calculated from the measured Dp/D0 and ka values. The deq increased with compaction level, suggesting that a very high compaction level creates well-connected macropores in the reduced total pore space of the cover soil. This is an important consideration when designing cover soils for optimally low water and high oxygen exchange while minimizing climate and toxic gas emissions from the waste layer to the atmosphere. © 2011 American Society of Civil Engineers.
• Extreme Compaction Effects on Gas Transport Parameters and Estimated Climate Gas Exchange for a Landfill Final Cover Soil

  Shoichiro Hamamoto, Per Moldrup, Ken Kawamoto, Praneeth Nishadi Wickramarachchi, Masanao Nagamori, Toshiko Komatsu

  JOURNAL OF GEOTECHNICAL AND GEOENVIRONMENTAL ENGINEERING 137 (7) 653 - 662 1090-0241 2011/07 [Refereed][Not invited]
   

  Landfill sites have been implicated in greenhouse warming scenarios as a significant source of atmospheric methane. In this study, the effects of extreme compaction on the two main soil-gas transport parameters, the gas diffusion coefficient (D-p) and the intrinsic air permeability (k(a)), and the cumulative methane oxidation rate in a landfill cover soil were investigated. Extremely compacted landfill cover soil exhibited negligible inactive soil-air contents for both D-p and k(a). In addition, greater D-p and k(a) were observed as compared with normal compacted soils at the same soil-air content (epsilon), likely because of reduced water-blockage effects under extreme compaction. These phenomena are not included in existing predictive models for D-p(epsilon) and k(a)(epsilon). On the basis of the measured data, new predictive models for D-p(epsilon) and k(a)(epsilon) were developed with model parameters (representing air-filled pore connectivity and water-blockage effects) expressed as functions of dry density (rho(b)). The developed D-p(epsilon) and k(a)(epsilon) models together with soil-water retention data for soils at normal and extreme compaction (rho(b)=1.44 and 1.85 g cm(-3)) implied that extremely compacted soils will exhibit lower D-p and k(a) at natural field-water content (-100 cm H2O of soil-water matric potential) because of much lower soil-air content. Numerical simulations of methane gas transport, including a first-order methane oxidation rate, were performed for differently compacted soils by using the new predictive D-p(epsilon) model. Model results showed that compaction-induced difference in soil-air content at a given soil-water matric potential condition is likely the most important parameter governing methane oxidation rates in extremely compacted landfill cover soil.DOI: 10.1061/(ASCE)GT.1943-5606.0000459. (C) 2011 American Society of Civil Engineers.
• Two-Region Extended Archie's Law Model for Soil Air Permeability and Gas Diffusivity

  Shoichiro Hamamoto, Per Moldrup, Ken Kawamoto, Lis Wollesen de Jonge, Per Schjonning, Toshiko Komatsu

  SOIL SCIENCE SOCIETY OF AMERICA JOURNAL 75 (3) 795 - 806 0361-5995 2011/05 [Refereed][Not invited]
   

  The air permeability (k(a)) and soil gas diffusion coefficients (D-p) are controlling factors for gas transport and fate in variably saturated soils. We developed a unified model for k(a) and D-p based on the classical Archie's law, extended by: (i) allowing for two-region gas transport behavior for structured soils, with the natural field moisture condition (set at -100 cm H2O matric potential [pF 2]) as the reference (spliced) point between the large-pore (drained pore diameter >= 30 mu m at pF <= 2) and the small-pore (subsequently drained pores <30 mu m at pF > 2) regions, and (ii) including a percolation threshold, set as 10% of the total porosity for structureless porous media or 10% of the porosity in the large-pore region for structured soils. The resulting extended Archie's law with reference point (EXAR) models for k(a) and D-p were fitted to the measured data. For both structureless and structured porous media, Archie's saturation exponent (n) was higher for D-p than for k(a), indicating higher water blockage effects on gas diffusion. For structured soils, the saturation exponent for the large-pore region (n(1)) was lower than for the small-pore region (n(2)). Generally, n(1) values of similar to 1 for k(a) and 2 for D-p and n(2) values of 4/3 for k(a) and 7/3 for D-p described the data well. Two reference-point expressions for k(a) at pF 2 were also developed and tested together with existing models for D-p at pF 2 against independent data across soil types. The best-performing reference-point models were a k(a) model based on the classical Kozeny equation and the Moldrup D-p model.
• 廃棄物処分場覆土におけるガス成分の分散特性

  濱本 昌一郎, 平野貴大, 川本健, 小松 登志子

  第17回地下水・土壌汚染とその防止対策に関する研究集会 107 - 110 2011 [Refereed][Not invited]
  
• Effect of water retention hysteresis on gas transport parameters in soils

  Sasanuma, K, S. Hamamoto, K. Kawamoto, T. Sasaki, T. Komatsu

  Proceedings of the Thirteenth International Symmer Symposium, Japan Society of Civil Engineers 223 - 226 2011 [Refereed][Not invited]
  
• Excluded-volume expansion of Archie's law for gas and solute diffusivities and electrical and thermal conductivities in variably saturated porous media

  Shoichiro Hamamoto, Per Moldrup, Ken Kawamoto, Toshiko Komatsu

  WATER RESOURCES RESEARCH 46 W06514  0043-1397 2010/06 [Refereed][Not invited]
   

  Describing and predicting gas and solute diffusivities and electrical and thermal conductivities under variably saturated fluid conditions are necessary for simulating gas, solute, and heat transport in soils. On the basis of comprehensive data for gas (D(p)) and solute (D(s)) diffusivities and electrical (EC) and thermal (TC) conductivities for differently textured and variably saturated soils, we investigated analogies and differences between the four parameters. At fluid (water or air) saturation, relative parameter values for D(p), D(s), and EC were all well described by an excluded- volume expansion of Archie's first law. The cementation exponent in Archie's first law was close to 1.5 for all parameters. At fluid- unsaturated conditions, relative values of D(p), D(s), and EC (normalized at fluid saturation) were well described by an excluded- volume expansion of Archie's second law. In the case of relative TC, the saturation exponent in Archie's second law was substituted by the inverse of it for the three other parameters since water bridge effects dramatically enhance the TC with increasing moisture contents in relatively dry porous media. If appropriate but different expressions for a percolation threshold in Archie's second law were applied for the four parameters, a saturation exponent value of around 2.0 generally gave accurate predictions of all four parameters for differently textured soils. Finally, the excludedvolume expansion of Archie's second law was modified to also represent porous media with bimodal pore size distribution and well- described data for D(p) and D(s) in aggregated soil.
• Hierarchical, Bimodal Model for Gas Diffusivity in Aggregated, Unsaturated Soils

  Augustus C. Resurreccion, Per Moldrup, Ken Kawamoto, Shoichiro Hamamoto, Dennis E. Rolston, Toshiko Komatsu

  SOIL SCIENCE SOCIETY OF AMERICA JOURNAL 74 (2) 481 - 491 0361-5995 2010/03 [Refereed][Not invited]
   

  The soil gas diffusion coefficient (D-p) and its dependency on soil air content, epsilon, and tortuosity-connectivity of the air-filled pore networks control the transport and fate of gaseous-phase contaminants in variably saturated soil. The bimodality in pore size distribution of structured soil often yields a variation of D-p with epsilon in the intraaggregate pore region that is distinctly different from that in the interaggregate region. Data imply a highly nonlinear behavior of soil gas diffusivity, D-p(epsilon)/D-o (where D-o is the gas diffusion coefficient in free air), in the interaggregate region of aggregated soils similar to that of structureless soils with a unimodal pore size distribution, probably due to diffusion-limiting effects by connected water films at low epsilon. In contrast, for the intraaggregate region, we show that the impedance factor F* (= D-p/epsilon D-o) and tortuosity factor T [= (1/F*)(1/2)] are approximately constant for most soil media. We suggest a typically well-defined separation between the two pore regions at the minimum for the pore connectivity factor X* [= log(D-p/D-o)/log(epsilon)], at which point the interaggregate pores are devoid of water while the intraaggregate pore region is water saturated. Based on this, a hierarchical two independent region (TIR) D-p/D-o model was developed by applying a cumulative series of Buckingham-Currie power-law functions, F epsilon(X). A nonlinear, water-content-dependent. expression for F best described the measured D-p/D-o in the interaggregate region, while constant F (around 0-5) and X(around 1) generally sufficed for the intraaggregate region. The TIR model better predicted gas diffusivities for both aggregate fractions and highly structured soils across the entire range of moisture conditions with MISE reduced by two to five times compared with traditional predictive D-p(epsilon)/D-o models.
• 地盤内の物質・熱輸送係数の統合的予測式を用いた処分場最終覆土層内のガス・熱輸送解析

  濱本 昌一郎, 川本健, 小松 登志子, Per Moldrup

  第16回地下水・土壌汚染とその防止対策に関する研究集会 551 - 555 2010 [Refereed][Not invited]
  
• Measurement of Gas Transport Parameters for Final Cover Soil at Maharagama Landfill in Sri Lanka

  Praneeth W, K. Ranasinghe, U. P. Nawagamuwa, K. Kawamoto, S. Hamamoto, P. Moldrup, T. Komatsu

  Proceedings of 19th World Congress of Soil Science 49 - 52 2010 [Refereed][Not invited]
  
• Effects of structure formation on gas transport parameters in differently repacked landfill final cover soils

  Wickramarachchi, P, S. Hamamoto, K. Kawamoto, P. Moldrup, T. Komatsu

  Proceedings of the 12th International Summer Symposium, Japan Society of Civil Engineers 207 - 210 2010 [Refereed][Not invited]
  
• Effects of moisture content and shrinkage on thermal properties for Hokkaido peaty soils

  Dissanayaka, S, S. Hamamoto, K. Kawamoto, T. Komatsu, P. Moldrup

  Proceedings of the 1st International Conference and Exploratory Workshop on Soil Architecture and Physico-Chemical Functions (CESAR) 69 - 72 2010 [Refereed][Not invited]
  
• Including organic matter in a predictive soil-gas diffusivity model

  Hamamoto, S, P. Moldrup, K. Kawamoto, T. Komatsu

  Proceedings of the 1st International Conference and Exploratory Workshop on Soil Architecture and Physico-Chemical Functions (CESAR) 135 - 138 2010 [Refereed][Not invited]
  
• Taking soil-air measurements towards soil-architectural fingerprints.

  Moldrup, P, S. Hamamoto, K. Kawamoto, T. Komatsu, S. Yoshikawa, L.W. de Jonge, P. Schjonning, O.H. Jacobsen, D.E. Rolston

  Proceedings of the 1st International Conference and Exploratory Workshop on Soil Architecture and Physico-Chemical Functions (CESAR) 229 - 234 2010 [Refereed][Not invited]
  
• Gas transport parameters in variably saturated landfill cover soils: Effects of soil type, compaction, and particle size fractions

  Wickramarachchi, P, K. Kawamoto, S. Hamamoto, P. Moldrup, T. Komatsu

  Proceedings of the 1st International Conference and Exploratory Workshop on Soil Architecture and Physico-Chemical Functions (CESAR) 413 - 416 2010 [Refereed][Not invited]
  
• Consolidation characteristics for Sri Lankan and Japanese clays: Void index in relation to stress states and sedimentation environment

  Yanase, Y, H. Tsuboi, S. Hamamoto, K. Kawamoto, T. Takemura, L.C. Kurukulasuriya, M. Oda

  Proceedings of the International Conference on Sustainable Built Environments (ICSBE), Special Session: Natural systems to control “Water Resources Pollution” and “Water Hazards,” 82 - 88 2010 [Refereed][Not invited]
  
• Effects of moisture content and shrinkage on soil-thermal properties for peat soils

  Hamamoto, S, S. Dissanayaka, K. Kawamoto, T. Komatsu

  Proceedings of the International Conference on Sustainable Built Environments (ICSBE), Special Session: Natural systems to control “Water Resources Pollution” and “Water Hazards,” 53 - 57 2010 [Refereed][Not invited]
  
• Effect of Particle Size and Soil Compaction on Gas Transport Parameters in Variably Saturated, Sandy Soils

  Shoichiro Hamamoto, Per Moldrup, Ken Kawamoto, Toshiko Komatsu

  VADOSE ZONE JOURNAL 8 (4) 986 - 995 1539-1663 2009/11 [Refereed][Not invited]
   

  The soil gas diffusion coefficient (D-p) and air permeability (k(a)) and their dependency on soil air content (epsilon) control gas diffusion and advection in soils. This study investigated the effects of average particle size (D-50) and dry bulk density (rho(b)) on D-p and k(a) for six sandy soils under variably saturated conditions. Data showed that particle size markedly affects the effective diameter of the drained pores active in leading gas through the sample at -100 cm H2O of soil water matric potential (calculated from D-p and k(a)) as well as the average pore diameter at half saturation (calculated from the water retention curve), both exhibiting similar and exponential relationships with D-50 Under variably saturated conditions, higher D-p and k(a) in coarser sand (larger D-50) were observed due to rapid gas diffusion and advection through the less tortuous large-pore networks. In addition, soil compaction (larger rho(b)) simultaneously caused reduced water blockage effects and a reduction of large-pore space, resulting in higher D-p(epsilon) but lower k(a)(epsilon). Two recent models for D-p(epsilon) and k(a)(epsilon) were evaluated: the water-induced linear reduction (WLR) model for D-p, and the reference-point power law (RPL) model for k(a), with reference point ka set at -100 cm H2O. The performance of both models for the sandy soils (particle size range 0.02-0.9 mm) was improved if the pore connectivity-tortuosity factor and water blockage factors were assumed to be functions of D-50 and rho(b). Water blockage factors, N for the WLR D-p(epsilon) model and M for the RPL k(a)(epsilon) model, showed a strong nonlinear relationship (R-2 = 0.95) that seems promising for predicting D-p(epsilon) from the more easily measureable k(a)(epsilon).
• The Solute Diffusion Coefficient in Variably Compacted, Unsaturated Volcanic Ash Soils

  Shoichiro Hamamoto, Mandadige Samintha Anne Perera, Augustus Resurreccion, Ken Kawamoto, Shuichi Hasegawa, Toshiko Komatsu, Per Moldrup

  VADOSE ZONE JOURNAL 8 (4) 942 - 952 1539-1663 2009/11 [Refereed][Not invited]
   

  The solute diffusion coefficient in soil (D-s) and its dependency on the soil water content (theta), soil type, and compaction govern the transport and fate of dissolved chemicals in the soil vadose zone. Only a few studies have quantified solute diffusivity (D-s/D-0, where D-s and D-0 are the solute diffusion coefficients in soil and pure water, respectively) for variably compacted soils with different textures. We measured the D-s for KCI on five different soils from Japan: two volcanic ash soils (Andisols) at different bulk densities, two sandy soils, and a loamy soil. The D-s was measured across a wide range of theta using the half-cell method. The D-s/D-0 values for Andisols with bimodal pore size distribution were comparatively lower than for the other soils. Opposite to the behavior for sandy soils, the D-s/D-0 for Andisols at a given theta decreased markedly with increasing bulk density under wet conditions but Increased with increasing bulk density under dry conditions. Data for all soil types including sandy soils with unimodal pore size distribution implied a two-region behavior when plotted as log(D-s/D-0) vs. theta. We suggest that the similar behavior across soil types can be explained by regions of low and high water phase connectivity for relatively structureless soils and by high Intraaggregate and low interaggregate water phase tortuosity for aggregated soils. Among a number of tested predictive models for D-s/D-0, the Penman-Millington-Quirk model, which requires knowledge of only theta and total porosity, performed best across soil types.
• Unified Measurement System for the Gas Dispersion Coefficient, Air Permeability, and Gas Diffusion Coefficient in Variably Saturated Soil

  Shoichiro Hamamoto, Per Moldrup, Ken Kawamoto, Toshiko Komatsu, Dennis E. Rolston

  SOIL SCIENCE SOCIETY OF AMERICA JOURNAL 73 (6) 1921 - 1930 0361-5995 2009/11 [Refereed][Not invited]
   

  The transport of gaseous compounds in soil takes place by gas diffusion, advection, and dispersion. Gas transport processes are influenced by tic soil-gas diffusion coefficient (D), air permeability (k(a)) and soil-gas dispersion coefficient (D-H), respectively. Of three gas transport parameters, DH is the least understood especially hov it is correlated to soil type, moisture conditions, and other transport parameters (i.e., D-P and k(a)). In this study, a unified measurement system (UMS) that enables sequential measurement of D-P, k(a), and D-H on the same soil core was developed. The experimental sequence is based on a two-chamber measurement of DH and k(a), followed by a one-chamber measurement of L P. Gaseous oxygen concentration and air pressure sensors are located in inlet and outlet chambers as well as at multiple points along the soil column. Using different particle-size fractions of non-aggregated (Toyoura sand) and aggregated (Nishi-Tokyo loam) soils, the effects of soil structure, particle (aggregate) size, and column scale (5-cm i.d. and 30-cm or 60-cm length) on the three gas transport parameters were investigated. For both soils, D-H linearly increased with increasing pore-air velocity. For Toyoura sand, gas dispersivity (lambda = D-H/u(0)) decreased with increasing soil-air content, while for Nishi-Tokyo loam, gas dispersivity decreased with increasing soil-air content to a minimum value when inter-aggregate pores were drained and increased again whether pores inside the soil aggregates started to act as tortuous air-filled pathways. In the arterial bore region (corresponding to the total pore volume for Narita sand and the inter-aggregate pore volume for Nishi-Tokyo loam), a linear relation between tortuosity of the air-filled pore network (T, calculated from D-P) and the gas dispersivity (lambda) was observed.
• Effect of aggregate structure on VOC gas adsorption onto volcanic ash soil

  Shoichiro Hamamoto, Katsutoshi Seki, Tsuyoshi Miyazaki

  JOURNAL OF HAZARDOUS MATERIALS 166 (1) 207 - 212 0304-3894 2009/07 [Refereed][Not invited]
   

  The understanding of the gaseous adsorption process and the parameters of volatile organic compounds such as organic solvents or fuels onto soils is very important in the analysis of the transport or fate of these chemicals in soils. Batch adsorption experiments with six different treatments were conducted to determine the adsorption of isohexane, a gaseous aliphatic. onto volcanic ash soil (Tachikawa loam). The measured gas adsorption coefficient for samples of Tachikawa loam used in the first three treatments, Control, AD (aggregate destroyed), and AD-OMR (aggregate destroyed and organic matter removed), implied that the aggregate structure of volcanic ash soil as well as organic matter strongly enhanced gas adsorption under the dry condition, whereas under the wet condition, the aggregate structure played an important role in gas adsorption regardless of the insolubility of isohexane. In the gas adsorption experiments for the last three treatments, soils were sieved in different sizes of mesh and were separated into three different aggregate or particle size fractions (2.0-1.0 mm, 1.0-0.5 mm, and less than 0.5 mm). Tachikawa loam with a larger size fraction showed higher gas adsorption coefficient, suggesting the higher contributions of macroaggregates to isohexane gas adsorption under dry and wet conditions. (C) 2008 Elsevier B.V. All rights reserved.
• EFFECTS OF BOUNDARY CONDITIONS ON SHAPE FACTOR FOR IN-SITU AIR PERMEABILITY MEASUREMENTS

  HAMAMOTO Shoichiro, KAWAMOTO Ken, NAGAMORI Masanao, KOMATSU Toshiko, MOLDRUP Per

  Doboku Gakkai Ronbunshuu C 公益社団法人 土木学会 65 (2) 579 - 586 2009 [Refereed][Not invited]
   

  In-situ air permeability (K_{a, insitu}) is a rapid field measurement that provides important information on soil-gas and water transport properties in soil. The K_{a, insitu} can be determined by using a shape factor taking account of field flow geometry effects on one-dimensional air flow. In this study, effects of lateral and bottom boundary conditions on the shape factor (G) and subsequent K_{a, insitu} were investigated by combining finite-element numerical simulations and a model experiment with repacked sand in a container. Results showed that calculated and measured values of G and K_{a, insitu} were highly dependent on the bottom boundary, and especially that a shallow zero-flux bottom boundary caused an underestimation of K_{a, insitu}. This shows that special care must be taken to determine the shape factor with due consideration to the proper boundary conditions. This is especially critical in the case of impermeable layers such as highly-compacted subsurface soil or a shallow groundwater table.
• Dense gas flow in volcanic ash soil: Effect of pore structure on density-driven flow

  Shoichiro Hamamoto, Takeshi Tokida, Tsuyoshi Miyazaki, Masaru Mizoguchi

  SOIL SCIENCE SOCIETY OF AMERICA JOURNAL 72 (2) 480 - 486 0361-5995 2008/03 [Refereed][Not invited]
   

  Unique physical properties of volcanic ash soils characterize the soil gas transport parameters of gas diffusivity and air permeability. Air permeability controls the density-driven flow that has been recognized as one of the important phenomena for subsurface dense gas. In this study, one-dimensional column experiments were conducted to investigate the effects of the pore structure of a volcanic ash soil on the density-driven flow of a dense gas (isohexane). The results showed that the overall horizontal gas movement in Tachikawa loam (volcanic ash soil) and Toyoura sand (sand) used as reference materials was expressed by Fick's diffusion law. On the other hand, the vertical downward gas movements in Tachikawa loam were considerably enhanced by the occurrence of density-driven flow, especially at high air contents (30-40%). Pore size distribution and pore structure analysis based on the tube model suggest that a greater volume of large pores (>0.01 cm) and a more continuous pore network led to the greater density-driven flow in Tachikawa loam than in Toyoura sand.

Books etc

• Descriptive-predictive models for mass and heat transport parameters in soil gaseous, liquid, and solid phases

  濱本, 昌一郎 
  Shoichiro Hamamoto 2010 xvi, 1, 198 p.

MISC

• マルチオミクスによるダイズ子実収量に関わる複合的要因解析

  村島和基, 丸山隼人, 渡部敏裕, 大津厳生, 草野都, 杉山暁史, 小林奈通子, 濱本昌一郎, 福島敦史, 大熊直生, 藤原風輝, 藤原風輝, 二瓶直登, 市橋泰範, 信濃卓郎  日本土壌肥料学会講演要旨集(Web)  69-  2023
• 土壌有機物が土壌中のCsの移動に与える影響

  辰野 宇大, 濱本 昌一郎, 二瓶 直登, 西村 拓  土壌の物理性  152-  39  -46  2022/11  [Refereed]
  
• Spatio-temporal variations on soil moisture and soil-gas behaviors in soybean field, \\and link to crop growths

  濱本 昌一郎  Journal of the Japanese Society of Soil Physics  151-  61  -67  2022/07/20
• Effect of cation exchange on colloid transport in saturated porous media

  HIGASHI Rikutaro, HAMAMOTO Shoichiro, NISHIMURA Taku  Journal of the Japanese Society of Soil Physics  150-  (150)  105  -113  2022/03/20  [Not refereed]
   

  Since colloidal particles in soils are known to act as a carrier of contaminants, understanding the transport behavior of colloidal particles in the soil is an important issue. This study investigates the transport behavior of colloidal particles during the cation exchange reaction between Ca2+ and Na+ at the surface of porous media. One-dimensional column experiments were conducted using Toyoura sand as the repacked porous media and carboxyl latex particles as the model colloid, respectively. It was found that colloidal particles deposited on the surface of the Toyoura sand during the cation exchange reaction, regardless of the amount of exchanged cation and the particle size of the applied colloids. The deposited colloidal particles were released when the ionic strength of the pore water decreased after the cation exchange reaction. The interaction energies between the latex particles and the sand surface were calculated based on the DLVO theory, suggesting the contribution of the attraction in the secondary minimum to the colloid deposition during cation exchange reaction.
• Soil Environment Analysis of Soybean Fields in Fukushima Prefecture

  二瓶直登, 濱本昌一郎, 杉山暁史, 熊石妃恵, 市橋泰範  日本作物学会東北支部会報  (65)  2022
• Estimating fine bubble concentration in water with a time domain reflectometry

  TANIGAWARA Ryunosuke, KOJIMA Yuki, HAMAMOTO Shoichiro, KAMIYA Kohji  Journal of the Japanese Society of Soil Physics  149-  47  -53  2021  

  In recent years, the use of fine bubbles (FBs) has been studied as a remediation method for groundwater contamination by volatile pollutants, and the behavior of FBs in soil has been elucidated. In this context, in-situ measurements of FB concentration in water and soil are required. In this study, we focused on the FB concentration in water. We investigated the estimation of FB concentration using the time domain reflectometry (TDR), a widely accepted method for measuring soil moisture content. FBs were generated in distilled water and surfactant solution, and the change in relative permittivity was measured with three different size TDR probes. The TDR probes were placed horizontally or vertically upward in water. The results showed that the FB concentration in distilled water was difficult to estimate due to its low concentration, while the FB concentration in surfactant solution may be captured. Relatively large bubbles originating from FB adhered to the TDR probes, and it caused an underestimation of the relative permittivity. It was found that the effect of air bubbles could be reduced by installing a relatively large probe vertically upward. The dielectric mixing model may be appropriate for converting the relative permittivity to FB concentration. These results indicate that the TDR has the potential to easily and effectively estimate the FB concentration in-situ. Comparison between TDR-based FB concentration and that measured with other methods is necessary to evaluate the accuracy of the TDR approach. It is expected that the TDR will be used to estimate the FB concentration in soil in the future.
• 日本地球惑星科学連合(JpGU)2021年大会 A-GE27 地質媒体における流体移動、物質移行 及び環境評価（Subsurface Mass Transport and Environmental Assessment）開催報告

  斎藤 広隆, 加藤 千尋, 濱本 昌一郎, 小島 悠揮, 森 也寸志  土壌の物理性  149-  73  -75  2021
• 15 根圏土壌におけるミネラル集積の機構に関する検討（関西支部講演会，2019年度各支部会）

  山﨑 真一, 落合 久美子, 本川 順子, 濱本 昌一郎, 杉山 暁史, 小林 優  日本土壌肥料学会講演要旨集  66-  242  -242  2020/09/01
• 日本地球惑星科学連合(JpGU) 2020 年大会 A-GE40 地質媒体における流体移動，物質移行及び環境評価 （Subsurface mass transport and environmental assessment） 開催報告

  斎藤 広隆, 濱本 昌一郎, 小島 悠揮, 森 也寸志  土壌の物理性  146-  19  -21  2020
• A review on application of 3D printer to geotechnical engineering

  TAKEMURA Takato, ISOBE Yusaku, OKUZAWA Koichi, SANOKI Satoru, SHIMO Michito, SUZUKI Kenichiro, SEIKI Takafumi, NISHIMOTO Soshi, HAMAMOTO Shoichiro, FUJII Yukiyasu  Japanese Geotechnical Journal  14-  (4)  377  -383  2019/12/25  [Not refereed]
   

  In recent years, technologies related to 3D surface measurement and 3D printer are spreading rapidly. The use of these technologies is no exception in geotechnical engineering, and many researches have been conducted to understand the mechanical and hydraulic behavior of geomaterials such as cracked and porous media. With the expectation that researchers and engineers involved in geotechnical engineering will have more opportunities to use 3D printer in the future, we review the latest researches on the application of 3D printer to geotechnical engineering.
• P8-1-7 溶存有機物による風化花崗岩土壌中のセシウムの移動促進効果（8-1 環境保全，2019年静岡大会）

  辰野 宇大, 濱本 昌一郎, 二瓶 直登, 西村 拓  日本土壌肥料学会講演要旨集  65-  135  -135  2019/09/03
• 地下熱環境の撹乱による地下水環境リスク評価に向けた研究紹介

  濱本昌一郎, 斎藤健志, 小松登志子  地盤工学会誌  67-  (4)  2019
• 地球惑星科学連合(JpGU) 2019 A-GE28 Subsurface mass transport, material cycle, and environmental assessment （地質媒体における物質移動，物質循環と環境評価）開催報告

  小島悠揮, 濱本昌一郎, 斎藤広隆, 森也寸志  土壌の物理性  143-  37  -38  2019
• 19 ダイズ根から分泌されたダイゼインの土壌中における動態解析（関西支部講演会，2017年度各支部会）

  奥谷 芙季, 濱本 昌一郎, 二瓶 直登, 西村 拓, 矢崎 一史, 杉山 暁史  日本土壌肥料学会講演要旨集  64-  285  -285  2018/08/29
• 液状化地盤における飽和度確認手法に関する実験的研究 －不飽和化液状化対策模型地盤を用いた模型振動台実験－

  中澤 博志, 永尾 浩一, 濱本 昌一郎, 前田 幸男, 須佐見 彩加, 神宮司 元治, 田端 憲太郎  420-  1  -62  2018/08
• Fine Bubble Transport in Porous Media towards Application for Soil Remediation

  HAMAMOTO Shoichiro  JAPANESE JOURNAL OF MULTIPHASE FLOW  32-  (1)  19  -25  2018/03/15  [Not refereed]
   

  Transport of fine bubbles (FBs) in porous media has drawn increasing attention, as a promising technology for soil and groundwater remediation. Understanding the transport characteristics of FBs in soils is essential to optimize FB-based remediation techniques. FB transport is highly influenced by flow rate, gas species, chemical properties of FB water such as pH and ionic strength. Transport models for colloidal particles including colloid filtration theory are applicable for characterizing FB transport in the porous media. In addition, DLVO theory representing interaction energy between colloidal particles and collector was helpful for understanding attachment mechanism of FBs in the porous media.
• Experimental studies on saturation degree measurements of desaturated soils for liquefaction mitigation

  永尾 浩一, 前田 幸男, 須佐見 朱加, 中澤 博志, 田端 憲太郎, 濱本 昌一郎, 神宮司 元治  佐藤工業技術研究所報 = Report of Satokogyo Technical Research Institute  (43)  48  -106  2018
• 地球惑星科学連合（JpGU）2018 年大会 開催報告

  濱本 昌一郎  土壌の物理性  140-  39  -39  2018
• A-GE31 Subsurface mass transport, material cycle, and environmental assessment 開催報告

  濱本 昌一郎, 小島 悠揮, 斎藤 広隆, 森 也寸志  土壌の物理性  140-  41  -42  2018
• EFFECT OF TEMPERATURE CHANGE ON DISSOLUTION CHARACTERISTICS AND CHEMICAL FORMS OF BORON AND ARSENIC IN SEDIMENTS

  SAITO Takeshi, HAMAMOTO Shoichiro, TAKEMURA Takato, UESHIMA Masato, KAWAMOTO Ken, KOMATSU Toshiko  Journal of Japan Society of Civil Engineers, Ser. G (Environmental Research)  74-  (1)  8  -15  2018  [Not refereed]
   

  The objective of this study was to clarify the effect of temperature change on dissolution characteristics and chemical forms of boron and arsenic in four sediments (obtained from 50 m length boring core) from the middle part of the Arakawa Lowland located north of the Tokyo metropolitan area, Japan. Dissolution experiment (fractionated as water-soluble (dissolved) fraction) of these four sediments was carried out under anaerobic and different temperature (15°C, 25°C, and 40°C) conditions. For the sediments after the dissolution experiment, sequential extraction method that selectively fractionates five chemical forms (exchangeable fraction, bound to carbonates, bound to iron and manganese oxides, bound to organic matter, and residual fraction) was applied. Especially for some sediments which were significantly affected by temperature change in the dissolution experiment, maximum dissolution amount, i.e., total amount of water-soluble and exchangeable fractions and bound to carbonates increased with increase in temperature. On the other hand, bound to iron and manganese oxides showed a decreasing trend with increasing temperature. These results suggested that bound to iron and manganese oxides containing boron and arsenic changed to relatively soluble fractions of boron and arsenic such as water-soluble and exchangeable fractions and bound to carbonates with temperature increase.
• Adsorption and Transport Behaviors of Potassium in Vermiculitic Soils

  Hamamoto, Shoichiro, Eguchi, Tetsuya, Kubo, Katashi, Nihei, Naoto, Hirayama, Takashi, Nishimura, Taku  Radioisotopes  67-  (3)  93  -100  2018  [Not refereed]
   

  It is important to understand potassium (K) behavior in soils since K fertilization is one of the most effective countermeasures to reduce the radiocaesium (RCs) uptake by crops. The K behavior in soils is highly influenced by the clay mineral composition. In this study, we investigated the K behavior for non-vermiculitic and vermiculitic nature of soils at Fukushima Prefecture in Japan. In the adsorption experiments, vermiculitic nature of soils exhibited more adsorption of K onto the soils as compared to non-vermiculitic nature of soil. One dimensional column transport experiments using ⁴²K as a radioisotope tracer showed that almost similar K mobility for all soils as supported by adsorption isotherms of K. However, percentage of exchangeable K in the total K retained in the soil was higher in non-vermiculitic nature of soil, while the percentage of fixed K was higher in vermiculitic nature of soils. Thus, the existence of vermiculite with high K fixation capacity was suggested to reduce K retention as an exchangeable form in vermiculitic nature of soils.
• 地盤工学分野へのマイクロ・ナノバブルの利活用

  濱本 昌一郎, 竹村 貴人, 鈴木 健一郎  地盤工学会誌  66-  66  -67  2018  [Not refereed]
  
• 1-1-3 土壌有機物がセシウムの移動に与える影響（1-1 物質循環・動態，2017年度仙台大会）

  辰野 宇大, 濱本 昌一郎, 二瓶 直登, 西村 拓  日本土壌肥料学会講演要旨集  63-  1  -1  2017/09/05
• 無人放射線測定により得られたγ線スペクトル上の特徴に基づく土壌中放射性セシウムの深度分布の推定

  越智康太郎, 佐々木美雪, 石田睦司, 佐藤友彦, 濱本昌一郎, 西村拓, 眞田幸尚  日本地球惑星科学連合大会予稿集(Web)  2017-  2017
• Report of a scientific session "A-GE39 Subsurface mass transport and environmental assessment" on JpGU 2017

  HAMAMOTO Shoichiro, KOJIMA Yuki, SAITO Hirotaka, MORI Yasushi  Journal of the Japanese Society of Soil Physics  137-  21  -23  2017
• 地球惑星科学連合（JpGU）2017 年大会 開催報告

  濱本 昌一郎  土壌の物理性  137-  19  -19  2017
• 粘土鉱物組成が放射性セシウム汚染土壌へのカリ施用の有効性におよぼす影響

  江口哲也, 若林正吉, 山田大吾, 平山孝, 濱本昌一郎, 二瓶直登, 久保堅司, 太田健, 信濃卓郎  農業農村工学会大会講演会講演要旨集(CD-ROM)  2017-  2017
• 8-1-18 交換性カリ含量が高まらない土壌の特性とカリの動態（8-1 環境保全，2016年度佐賀大会）

  久保 堅司, 平山 孝, 竹内 恵, 藤村 恵人, 江口 哲也, 二瓶 直登, 濱本 昌一郎, 齋藤 隆, 太田 健, 信濃 卓郎  日本土壌肥料学会講演要旨集  62-  148  -148  2016
• Effect of temperature change in chemical forms of trace elements in the latest Pleistocene and Holocene sediments

  斎藤 健志, 植木 崇, 濱本 昌一郎  地下水・土壌汚染とその防止対策に関する研究集会講演集  21-  213  -216  2015/06/18
• Discussion at the 56th symposium on the restoration of Tsunami affected farmland in Miyagi prefecture

  濱本 昌一郎  土壌の物理性 = Journal of the Japanese Society of Soil Physics  (129)  31  -35  2015/03
• 地下帯水層の長期的温度変化が地下水質に及ぼす影響

  釼持将人, 釼持将人, 植木崇, 植木崇, 斎藤健志, 斎藤健志, 濱本昌一郎, 濱本昌一郎, 川本健, 川本健, 小松登志子, 小松登志子  地下水・土壌汚染とその防止対策に関する研究集会講演集(CD-ROM)  21st-  2015
• 地下水質に対する地下温度上昇の影響

  釼持将人, 斎藤健志, 濱本昌一郎, 川本健, 小松登志子  地盤工学会関東支部発表会(CD-ROM)  12th-  2015
• P32. Behavior of fine-bubble of suspension water associated with Improved Fresh-Water Core Sampling

  Ueda Masato, Takemura Takato, Hamamoto Shoichiro  研究発表会講演論文集  27-  197  -198  2015
• Influence of ultra-fine bubble water on various ion absorption of the soybean seedling

  Nihei Naoto, Hamamoto Shoichiro, Sugiyama Akifumi, Tokuda Yomei, Ueda Yoshikatsu  Abstracts of Meeting of the CSSJ  239-  160  2015
• Effect of reducing the test period on estimating effective thermal conductivity from Kelvin's line source function in thermal response test : a numerical study

  Moldrup P.  土壌の物理性 = Journal of the Japanese Society of Soil Physics  128-  (128)  11  -20  2014/12  

  地盤熱応答試験(TRT)で，ケルビンの線源関数の近似解からみかけ熱伝導率λeを推定する場合，48時間以上の試験時間が推奨されている。近年線源関数の漸近解を用いて試験初期のデータを用いた解析が提案され，試験時間の大幅な短縮の可能性が示された。本研究では数値解析を用いて，解析に用いるデータ区間がλeの推定に与える影響明らかにし，試験時間短縮の可能性について検討した。三次元の熱伝導方程式に一次元の移流熱移動方程式を組み合わせ，熱媒体からU字管本体への熱移動については吸込み・湧出し項の中で扱った。異なる条件下で熱媒体温度を求め，線源関数の近似解と漸近解を用い，みかけ熱伝導率を推定した。漸近解を用いることで，グラウトの熱特性が地盤と大きく異なる場合でも，誤差5%以内で試験時間を20時間以内に短縮できた。また，現場TRTデータの解析により，上記結果の正当性が評価できた。
• Reviewing classical studies in soil physics : "Transport in Porous Media" by R. J. Millington and J. P. Quirk

  HAMAMOTO Shoichiro, NISHIMURA Taku  Journal of the Japanese Society of Soil Physics  128-  (128)  39  -46  2014/12  

  土壌中の物質移動を理解.予測する上で,土壌の物質輸送係数の把握および正確な予測モデルの存在は必要不可欠である.本報では,土壌の拡散係数予測モデルとして有名な Millington and Quirk モデルを取り上げ,Millington and Quirk (1960)を中心にモデルの導出過程,その性質を紹介した.彼らは,球状の間隙がランダムに分布する間隙モデルに基づき,流れに寄与する有効間隙割合と,異なる間隙径間での連結確率を考慮して固有透過度と拡散係数に関する理論モデルを構築した.Millington and Quirk モデルをベースに拡散係数予測モデルの改良は進んでいるものの,彼らのモデルのようにシンプルで扱いやすい理論モデルは未だ存在しない.
• Changes in subsurface temperature and groundwater quality during thermal loading and natural cooling processes in confined aquifers of Arakawa Lowland, Japan

  斎藤 健志, 植木 崇, 濱本 昌一郎  地下水・土壌汚染とその防止対策に関する研究集会講演集  20-  114  -117  2014/06/19
• 荒川低地完新世堆積物の重金属の存在形態とその溶出特性に温度変化が与える影響

  植木崇, 栗原由衣, 斎藤健志, 斎藤健志, 濱本昌一郎, 濱本昌一郎, 川本健, 川本健, 小松登志子, 小松登志子  地下水・土壌汚染とその防止対策に関する研究集会講演集(CD-ROM)  20th-  2014
• 荒川低地地下帯水層の温度変化が地下水質に与える影響

  斎藤健志, 斎藤健志, 植木崇, 植木崇, 濱本昌一郎, 濱本昌一郎, 川本健, 川本健, 小松登志子, 小松登志子  日本地下水学会講演会講演予稿  2014-  2014
• これまでの研究生活を振り返って

  濱本 昌一郎  土壌の物理性  127-  31  -32  2014
• Discussion at the 55th symposium on the radioactive material issue

  HAMAMOTO Shoichiro  Journal of the Japanese Society of Soil Physics  126-  45  -49  2014
• Temperature dependence of solute dispersion characteristics in soils

  有原 萌恵, 濱本 昌一郎, 川本 健  地下水・土壌汚染とその防止対策に関する研究集会講演集  19-  502  -504  2013/06/13
• Effects of long-term temperature change in subsurface on pore water composition

  栗原 由衣, 濱本 昌一郎, 川本 健  地下水・土壌汚染とその防止対策に関する研究集会講演集  19-  97  -100  2013/06/13
• Pore structure analysis using microfocus Xray CT and measurements of mass transport parameters for different sandy soils

  小池 拓也, 濱本 昌一郎, 川本 健  地下水・土壌汚染とその防止対策に関する研究集会講演集  19-  280  -282  2013/06/13
• 温度変化が土壌中重金属の存在形態に与える影響

  栗原由衣, 植木崇, 濱本昌一郎, 斎藤健志, 川本健, 小松登志子  地盤工学会関東支部発表会(CD-ROM)  10th-  2013
• 荒川低地沖積層の間隙水組成に温度変化が与える影響

  植木崇, 栗原由衣, 斎藤健志, 濱本昌一郎, 川本健, 小松登志子  地盤工学会関東支部発表会(CD-ROM)  10th-  2013
• PE-008 地下水中の微生物叢に対する地下温度上昇の影響(微生物群集構造,ポスター発表)

  大久保 智司, 斎藤 健志, 濱本 昌一郎, 大西 純一, 小松 登志子  (29)  118  2013
• PE-009 関東平野の地下帯水層土壌に含まれる真正細菌叢の網羅的解析(微生物群集構造,ポスター発表)

  大西 純一, 大久保 智司, 斎藤 広隆, 竹村 貴人, 濱本 昌一郎, 小松 登志子  (29)  119  2013
• Effect of Soil-Water Retention Hysteresis on Gas and Heat Transport Parameters

  濱本 昌一郎, 川本 健, 小松 登志子  CACS FORUM  3-  (3)  6  -11  2012  

  type:text Knowledge of soil-gas and heat transport parameters is essential for simulating behaviors of greenhouse/toxic gases and changes in soil temperature in natural and man-made soil ecosystems, for example in urban polluted soil sites and the soil cover layer at municipal landfill sites. Degree of water-saturation at different water potentials (as described by the soil-water retention curve) highly affects both gas and heat transport parameters. In this study, the effects of water retention hysteresis (non-singularity in the wetting and drainage curves of soil-water retention) on the soil-gas diffusion coefficient (Dp), air permeability (ka), and thermal conductivity (K) were investigated. Different sand size fractions representing different particle shapes were used for measuring gas and heat transport parameters. Soil-water retention hysteresis highly affected the gas transport parameters, showing higher Dp and ka values for the wetting processes than those for drying processes at the same air content. This suggests that the existence of more continuous pore-networks for the wetting processes enhanced diffusive and advective gas transport. Opposite to the behavior of the gas transport parameters, the effect of soil water retention hysteresis on K was insignificant for all sand materials.
• Geothermal property and groundwater flow estimated from the lithology in the Setagaya and Suginami district, Tokyo, central Japan

  Funabiki Ayako, Takano Yoichi, Takemura Takato, Hamamoto Shoichiro, Komatsu Toshiko  Proceedings of the General Meeting of the Association of Japanese Geographers  2012s-  100226  2012  

  The ground source heat pump (GSHP) is a highly efficient and renewable energy technology for space heating and cooling, with benefits including energy conservation and reduction in greenhouse gases emission. On the other hand, the GSHP installation under the ground might enhance pollutions in geo- heat environment due to thermal disturbance released from GSHP.
  In this study, we culcurated the heat transfer coefficient and ground water flow based on the 3D geological model. Thenm we considered the best point for GSHP in part of Suginami and Setagaya district, Tokyo, Japan.
• Groundwater flow and geological model estimated from the borehole log data in the Setagaya and Suginami district, Tokyo, Japan

  Funabiki Ayako, Takemura Takato, Hamamoto Shoichiro, Komatsu Toshiko  Annual Meeting of the Geological Society of Japan  2012-  534  2012
• P26. Groundwater surface and groundwater flow estimated from the lithology in the Setagaya and Suginami district, Tokyo, central Japan

  Funabiki Ayako, Takemura Takato, Hamamoto Shoichiro, Komatsu Toshiko  研究発表会講演論文集  24-  191  -192  2012
• 地中熱ヒートポンプシステムの利用に関する環境影響評価~さいたま市における地下水・地盤環境特性~

  斎藤健志, 斎藤健志, MON Ei Ei, 濱本昌一郎, 濱本昌一郎, 竹村貴人, 竹村貴人, 斎藤広隆, 斎藤広隆, 大西純一, 大西純一, 小松登志子, 小松登志子  日本地下水学会講演会講演要旨  2011-  2011
• P40. Hydraulic, geothermal and geological properties of the Pleistocene sediment core drilled at Setagaya-ku, Tokyo

  TAKEMURA Takato, FUNABIKI Ayako, KOMATSU Toshiko, HAMAMOTO Shoichiro, SAITO Hirotaka, ONISHI Jyunichi  研究発表会講演論文集  23-  219  -220  2011
• Gas Advection and Dispersion Phenomena in Soil

  HAMAMOTO Shoichiro, SHIMOWADA Yoshiki, SUGIMOTO Yuichi  Water,Land and Environmental Engineering  76-  (10)  921  -923  2008  [Refereed]
  

Research Grants & Projects

• Comprehensive study on radiocesium absorption by soybean

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

  Date (from‐to) : 2021/04 -2025/03 

  Author : 二瓶 直登, 高橋 秀和, 市橋 泰範, 平賀 勧, 濱本 昌一郎, 小林 奈通子, 岡野 夕香里, 辰野 宇大

   

  （ア）Cs吸収に関与する遺伝的制御について、これまでに得た複数の候補遺伝子から選抜し、その欠損体を用いた評価を行った。また、異なる環境で栽培したダイズのRNA-seq解析に基づく検討により、Cs吸収を担う候補遺伝子を同定した。 （イ）土壌の多様な成分や微生物、物理性を含めた栽培環境がダイズのCs吸収能に与える影響を明らかにするため、福島県内でダイズが栽培されている圃場から土壌、微生物のデータを包括的に取得した。 （ウ）福島県内でダイズのコアコレクション（337品種）を栽培し、開花期の葉、子実の133Cs濃度を測定した。葉と子実の133Cs濃度比を用いてゲノムワイド関連解析（GWAS）により、葉から子実へ移行する候補遺伝子の同定を試みた。分析が済んだ85品種の葉、子実のCs濃度、および葉と子実のCs濃度比の最大値と最小値はそれぞれ22倍、24倍、97倍であった。葉と子実のCs濃度比についてGWAS解析を行った結果、p値が高い(7.5以上)ローカスがいくつか検出された。 （エ）基肥でK施肥を行うとCs吸収抑制効果は高かったが、K追肥ではCs抑制効果はみられなかった。またCa施肥については土壌型により結果が異なり、灰色低地土ではCs濃度が低下したが、黒ボク土ではCs濃度の低下はせず、Ca輸送体の関与は判然としなかった。作物が吸収しやすい分画(F1)としにくい分画(F2)に分けて検討したところ、ダイズのCs吸収はイネやソバよりF2分画の割合が高く、ダイズは広い分画のCsを吸収することが示された。 （オ）ダイズのCs蓄積経過を明らかにするため生育期間中の一定期間だけCsを供給して水耕栽培をしたところ、ダイズのCs吸収はK、Caと同様に生育後半まで続いた。また、およそ55%が転流によって蓄積したものであり、45%が根から直接吸収して子実に蓄積したと算出された。
• Transport of Colloidal Particles in Unsaturated Soils

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

  Date (from‐to) : 2021/04 -2024/03 

  Author : 濱本 昌一郎, 竹村 貴人, 大竹 豊, 石田 尚之, 杉本 卓也

   

  本研究では，気液界面存在下における多孔質体中のコロイド粒子挙動の実態把握に基づき、不飽和土壌内でのコロイド粒子の土壌内移動特性を解明することを目的とする。本年度はまず、X線CTを用いた不飽和土壌の間隙構造のキャラクタリゼーションと、間隙構造パラメータと各種物質輸送係数の関係について調べた。粒径の異なる砂試料を用いて、異なる水分状態（完全飽和、封入不飽和、連続不飽和（脱水・吸水過程））にある砂充填カラムを作成し、物質輸送係数として飽和・不飽和透水係数、ガス拡散係数、通気係数を測定した。また各水分条件において、X線CT装置を用いて液相・気相の間隙径分布に加え、各相の屈曲度・連結性を定量的に評価した。結果、封入空気の気泡径と分布が封入不飽和状態下での透水係数の低下度に大きく影響を与えること、同一水分条件下で吸水過程は脱水過程に比べ粗大間隙ネットワークの連結性が高く、結果としてガス拡散係数および通気係数が高くなること、など気液界面存在下における間隙構造と物質輸送特性に関する貴重な基礎的知見が得られた。さらに本年度は、間隙水の化学的特性が多孔質体中のコロイド挙動に与える影響を調べるため、Na+やCa2+などのイオン種やイオン濃度を変えた条件で砂充填カラムへのラテックス粒子注入実験を行った。二価陽イオン存在下ではコロイド粒子沈着が促進することや、NaとCaとのイオン交換反応時における沈着コロイド粒子の脱離挙動が、DLVO理論に基づくコロイド粒子と充填粒子表面との相互作用力によって説明できることを示した。また次年度に向けて、マイクロ間隙流路を用いたコロイド粒子挙動直接観察の装置セットアップや、AFMを用いたコロイド粒子と充填粒子表面との相互作用力測定に関する実験を開始した。
• バブル態メタンの土壌内挙動の解明とメタンガス運命予測モデルの構築

  日本学術振興会：科学研究費助成事業 挑戦的研究(萌芽)

  Date (from‐to) : 2019/06 -2021/03 

  Author : 濱本 昌一郎, 常田 岳志, 小島 悠揮

   

  2020年度は、模擬水田土壌カラムを用いたメタンバブル挙動に関する室内実験を行った。本研究課題で研究対象とするつくば市の水田土壌から採取した攪乱土壌を直径5cm高さ6cmのアクリル製カラムに水中充填し、恒温室内にて約１か月培養した。稲わらを混入したカラムを準備し、稲わら投入によるメタンバブル生成速度の違いを検討した。カラムにはThermo-TDRを設置し、培養期間中の誘電率および熱特性変化を調べた。結果、稲わら投入カラムでは培養開始から１週間程度でメタンバブルの生成が見られ、バブル生成に伴って誘電率および熱物性の変化が見られた。特に、誘電率と熱容量はバブル量の増加とともに低下し、次年度実施するメタンバブルの生成量評価に関する現場モニタリングに関してこれらの物理量が有効な指標となることが確認できた。一方、稲わらを投入しなかったカラムでは、培養期間中バブルの生成は確認できなかった。このように、室内実験を通して有機物施用によりメタンバブルの生成が促進されることが確認できた。また、稲わらを投入したカラムを用いてＸ線CT撮影を行った。地表面から3㎝深度でメタンバブルの存在が確認でき、画像解析から個々のバブル体積や等価径、個数を算出した。一方で、湛水直下ではメタンバブル存在量は少なく、メタンバブルの深度分布について貴重な実験データが得られた。今後は培養温度や稲わら投入割合など諸条件を変化し、環境条件とメタンバブル生成速度に関する実験データを蓄積する予定である。
• Understandings and model developments of transport characteristics of nano-materials in soils

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

  Date (from‐to) : 2018/04 -2021/03 

  Author : hamamoto shoichiro

   

  The objective of this study was to characterize the transport characteristics of nanoscale materials (NMs) including nanobubbles (NBs) and nanoparticles (Carboxylate latex, CL) in porous media. Laboratory column experiments using NMs revealed that the presence of deposited colloidal particles and multivalent ions inhibited the transport of NBs or CLs within the porous media, and that the desorption of deposited NBs or CLs was enhanced as the ionic strength of the porewater decreased. These behaviors of NBs in the porous media could be expressed by advection-dispersion equations considering reversible and irreversible attachment and desorption between NMs and packed particles.
• Molecular and mathematical basis of rhizosphere metabolodynamics

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

  Date (from‐to) : 2018/04 -2021/03 

  Author : Sugiyama Akifumi

   

  The rhizosphere is a pivotal area for plant growth and health. However, it is difficult to distinguish between the rhizosphere and the non-rhizosphere (bulk) in the field environment, since the rhizosphere changes according to the growth of plants. Using daidzein, an isoflavone secreted from soybean roots, as a model, we aimed to define the rhizosphere area based on the dynamics of plant metabolites secreted from the roots in the rhizosphere. The movement of daidzein in the rhizosphere was simulated by the governing equation of daidzein movement. It was calculated that the distribution of daidzein was limited to a very small region from the root. To verify this result, we grow soybeans in rhizobox and field. It was confirmed that this simulation was applicable to estimate the dynamics of daidzein in the rhizosphere.
• Study of fine bubble behavior in ground in liquid-air-chemical coupled field

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

  Date (from‐to) : 2016/04 -2019/03 

  Author : TAKEMURA Takato, SUZUKI Kenichiro

   

  In this study, we investigated the physicochemical properties of fine bubbles, and analyzed the behavior of fine bubbles in the ground under a gas - liquid - chemical coupled field. In addition, in-situ test was carried out to understand the behavior of fine bubble. Based on these results, we estimated the movement area and environmental impact of O 2 / CO 2 fine bubbles in the ground, and proposed an efficient CO2 underground neutralization treatment method using fine bubbles. As a result, the influence of the pH condition of the injected solution on the migration characteristics of the fine bubble and the existence lifetime of the fine bubble under different pH conditions were clarified by experiments. Moreover, we evaluated the behavior of fine bubbles in the aquifer for CO2 underground neutralization treatment from the in-situ test.
• Understanding of radioceasum uptake by roots and mass transport model in rhizosphere

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research

  Date (from‐to) : 2016/04 -2019/03 

  Author : Hamamoto Shoichiro, NISHIMURA taku

   

  There are soils where applied Potassium (K) does not effectively work for reducing radioceasum (RCs) uptake by plant roots. In this study, K and RCs movements in such soils were investigated based on the column and batch experiments. In addition, using a rhizobox, effects of clay minerals on water and ion transport near roots was investigated. Results showed that the soils containing vermiculite highly adsorb the applied K as a fixed form, reducing exchangeable K in soils. In addition, rhizobox experiments showed that RCs and K uptakes and those concentration nearby roots were highly reduced when the vermiculite was applied to the soils.
• Modeling re-distribution of radioactive cesium deposited by the accident of Fukushima Dai-ichi nuclear power station and predicting influences of the cesium in livelihood area

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)

  Date (from‐to) : 2015/04 -2018/03 

  Author : Nishimura Taku, Renschler Chris, Hamamoto Shoichiro, Yamasaki Takuhei, Nihei Naoto, Yoshida Shuichiro, Kogure Toshihiro, Okumura Taiga, Hadano Satoshi

   

  In this study, we confirmed discharge of radioactive Cs (RCs) is small and was correlated with sediment discharge. However, the relationship between RCs and sediment discharges has changed by a flooding during large typhoon at summer of 2015. From an examination of a smaller forested watershed by a combination of numerical simulation, monitoring of river discharge and ground truth revealed that quite limited area in the forest floor contributed sediment and RCs discharges from the forest. This suggested low annual RCs discharge rates from forests. Observation and analysis by transmission and scanning electron microscopy and energy dispersive X-ray spectrometry suggested cesium-bearing particle in river water samples had a role on radioactivity of the water samples, especially the sample contained less suspended solids.
• Study on salt accumulation process in response to carbon cycle in soils

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research

  Date (from‐to) : 2014/04 -2017/03 

  Author : Nishimura Taku, HAMAMOTO Shoichiro, IMOTO Hiromi, ISHIBASHI Sakuya

   

  Salt accumulation is a world-wide issue at arid and semi-arid regions. Problems of sodic soils and reclamation of the soil by using Ca amendments have been studying for several decades. Besides, vast salt accumulated areas are covered by carbonates such as calcium carbonate, too. Carbonates are often less soluble with water and this made carbonates accumulations difficult to be remediated. However, carbonates attain equilibrium with water and CO2 in soil air phase. CO2 concentration of soil air phase may be far greater than that in atmosphere due to soil respiration, and this may enhance solubility of carbonates. To discuss role of variable soil CO2 concentrations on carbonates fate and sodic soil reclamation, we constructed laboratory soil column experimental scheme. In the column, soil CO2 concentration can be controlled as well as soil moisture and CO2 concentration can be monitored continuously.
• Transport and fate of micro-bubble in soil

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (A)

  Date (from‐to) : 2014/04 -2017/03 

  Author : Hamamoto Shoichiro, NIHEI Naoto, UEDA Yoshikatsu, TAKEMURA Takato, NAKAZAWA Hiroshi

   

  Potential applications of fine bubbles (FBs) have drawn more attention, especially in environmental engineering fields such as soil/groundwater remediation. Understanding a transport mechanism of FBs in soils is essential to optimize remediation techniques using FBs. In this study, transport characteristic of FBs in soils was investigated based on the column transport experiments. In addition, a transport model of FBs was tested. The column transport experiments using glass beads were conducted, where UFBs created by either air or oxygen were injected to the column with different flow conditions. The results showed that attachments of FBs were enhanced under lower water flow rate. In addition, the mobility of O2-FBs which has lower zeta potential was higher than that of Air-UFBs. A convection-dispersion model including bubble attachment and detachment terms was applied to the obtained breakthrough curves for each experiment, showing good fitness against the measured data.
• 地盤内の気泡挙動解析モデル構築と気泡注入工法の最適化にする研究

  日本学術振興会：科学研究費助成事業 基盤研究(C)

  Date (from‐to) : 2013/04 -2014/03 

  Author : 岩下 和義, 濱本 昌一郎

   

  本研究の目的は、気泡の物理特性および注入条件が地盤の不飽和化ならびに液状化強度に与える影響を解明することである. H25年度では、使用するマイクロバブルの安定性評価のために、異なる界面活性剤を使用した時の水中マイクロバブルの持続性や生成されるマイクロバブル径分布について調べた。結果、界面活性剤としてSDSを用いさらに水中SDS濃度を臨界ミセル濃度以上にした場合で、最も水中マイクロバブルが安定して存在することが分かった。生成されるマイクロバブル径は5-100μmであった。また、マイクロバブルの地盤内挙動把握を目的とし、飽和砂質地盤へのマイクロバブル注入実験を室内カラム試験より実施した。粒径の異なる砂試料を異なる締固め度でステンレス製カラムに充填し、カラムにマイクロバブル水を注入した。結果、通水中にマイクロバブルが砂試料内に補足されるために、通水流量および流出後のマイクロバブル濃度は時間とともに低下する結果が得られた。しかしながら、流出後と流入時のマイクロバブル径分布を比較した場合、両者に大きな差が見られず特定の径のマイクロバブルが試料内で捕捉されるという現象は確認されなかった。マイクロバブルの捕捉率は砂試料の粒径が小さいほど高く、通水後の飽和度は約70%程度まで低下することが分かった。一方で、同粒径砂試料を用いた場合、試料の締固め度の違いがマイクロバブルの捕捉率に与える影響は小さい結果が得られた。本研究を通して、マイクロバブルの地盤内挙動に関する重要な基礎的知見が得られた。
• Developments of predictive models for mass transport and mechanical properties considering subsurface temperature

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)

  Date (from‐to) : 2012/04 -2014/03 

  Author : HAMAMOTO Shoichiro

   

  In this study, we aimed at understandings of temperature dependencies on mass transport and mechanical properties of soils, and conducted oedometer tests and solute transport experiments under temperature control using Kaolin and alluvial clays. The oedometer tests using Kaolin clays showed temperature increase enhanced consolidation yield stress, consolidation index, and shear modulus possibly due to an increased cementation between soil particles. Temperature dependency on solute transport characteristic confirmed higher hydraulic conductivity and solute diffusion coefficient for samples at higher temperature. This trend could be expressed by modifying existing predictive models for those parameters. In addition, solute transport experiments using alluvial clays showed that temperature dependency on solute dispersion coefficient was not so significant as compared to retardation factor.
• Mass and heat transport in landfill covers and environmental risk assessment

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Research Activity start-up

  Date (from‐to) : 2010 -2011 

  Author : HAMAMOTO Shoichiro

   

  In this stud, using landfill covers with different physical properties such as compaction levels or moisture conditions, laboratory experiments for understanding gas transport characteristics were conducted. By combining the obtained results from the laboratory experiments with literature data for mass and heat transport parameters for variably-textured soils, unified predictive models for mass and heat transport parameters were proposed, which enable to simulate gas, solute, heat transport in landfill covers with different physical properties.
• 土壌における揮発性有機化合物のガス態移動機構の解明と環境リスク評価

  日本学術振興会：科学研究費助成事業 特別研究員奨励費

  Date (from‐to) : 2008 -2009 

  Author : 濱本 昌一郎

   

  平成21年度では、前年度に引き続き土壌中の移流・分散現象を再現したカラム実験を行い、土壌中のガス挙動を支配するガス輸送係数であるガス拡散係数・通気係数・ガス分散係数の相関関係把握および予測式構築を行った。さらに、土壌中のガス移動に加え、土壌中の溶質移動、熱移動、電気移動にも研究対象を広げ、これらの物質・熱移動を支配する物質輸送係数(ガス輸送係数、溶質拡散係数、熱伝導度、電気伝導度)間の類似性・相違について調べた。研究を通して、修正アーチー式をもとに、単粒構造を有する砂質土および団粒構造を有する団粒土に適用可能な、土壌の物理特性を考慮した物質・熱輸送係数予測式を構築した。構築した予測式を用いて、廃棄物処分場内における汚染・温室効果ガスおよび熱輸送の数値解析を行った。数値解析結果と現場における実測データとの比較、廃棄物処分場の汚染・温室効果ガス放出制御および安定化促進に向けた工学的手法の提案を行った。一般的に廃棄物処分場では廃棄物層の上方に覆土層が施工される。数値解析の結果、覆土層を極度に締固めた場合、緩詰め地盤に比べ、高い水分保持特性に起因して低いガス移動特性を導くことが分かった。一方で、メタンガスのように地表面付近で酸化されやすいガスでは、メタン酸化能力の低下により緩詰め地盤よりも温室効果の高いメタンガスがより放出されることが分かった。また、効果的に処分場からのガス放出を制御するためには、最低50cmの覆土層を確保する必要があることが示唆された。覆土層を極度に締固めた場合では、熱輸送がより促進され、廃棄物層から放出される熱はより早くに外気温と平衡に達し、覆土層の極度の締固めが処分場の安定化に寄与することが分かった。