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Nakahara Osamu

Research Faculty of Agriculture　Fundamental AgriScience Research　Bioscience and ChemistryAssociate Professor

Researcher basic information

■ Degree
  • 博士(農学), 九州大学
■ URL
researchmap URLホームページURL■ Various IDs
J-Global ID■ Research Keywords and Fields
Research Keyword
  • 窒素飽和
  • 窒素降下物
  • 窒素吸収
  • 物質循環
  • アロフェン
  • 窒素循環
  • 地球温暖化
  • イオン交換
  • 圃場管理
  • Freundlich等温吸着式
  • 富栄養化
  • イモゴライト
  • 窒素施肥
  • 森林生態系
  • 火山灰土壌
  • 硝酸態窒素
  • 窒素除去
  • モンテカルロシミュレーション
  • 無機化
  • 農耕地生態系
  • 養分循環
  • 有機物分解
  • 養分制限
  • 硝酸溶脱
  • 二酸化炭素
  • イオン吸着
  • 温帯林
  • RPモデル
  • アンモニウム
  • 物質移動
Research Field
  • Life Science, Plant nutrition and soil science
  • Environmental Science/Agriculture Science, Rural environmental engineering and planning
■ Educational Organization

Career

■ Career
Career
  • 2009 - 2011
    Hokkaido University, (連合)農学研究科(研究院), 准教授

Research activity information

■ Papers
  • Adsorption and retarded transport of nitrate in Andisol subsoils caused by the apparent salt sorption
    TAMURA Kazuki; NAKAHARA Osamu; TANAKA Shoichi; KATOU Hidetaka; HASEGAWA Shuichi
    Japanese Journal of Soil Science and Plant Nutrition, 82, 2, 114, 122, Japanese Society of Soil Science and Plant Nutrition, Apr. 2011, [Peer-reviewed]
    Japanese, Scientific journal, Adsorption and retarded transport of nitrate (NO_3^-) was studied using 9 Andisol subsoils in Japan. In all the soils investigated, NO_3^- adsorption in the NO_3^- concentration of 0-14mM was caused almost exclusively by the apparent salt sorption, the simultaneous adsorption of equivalent amounts of cations and anions, and was not accompanied by the desorption of indigenous sulfate through anion exchange. The NO_3^- adsorption was approximated by a linear adsorption isotherm with the distribution coefficient, K_d, ranging from 0.3 to 1.6L kg^<-1>, which suggests that 25 to 70% of NO_3^- in the subsoils were in the adsorbed phase. Nitrate transport in repacked soil columns showed increasing delay of NO_3^- breakthrough with the increase in K_d. Retardation factor, R, obtained by fitting the convection-dispersion model to the experimental NO_3^- breakthrough curves ranged from 1.3 to 3.2, and was in close agreement with that estimated from K_d for each soil. These results suggest that, in the absence of preferential flow, NO_3^- travel distance is 0.3 to 0.8 times that of water flow, and can be predicted using K_d obtained from batch adsorption experiments.
  • Soil and stream water acidification in a forested catchment in central Japan
    Nakahara, O; Takahashi, M; Sase, H; Yamada, T; Matsuda, K; Ohizumi, T; Fukuhara, H; Inoue, T; Takahashi, A; Kobayashi, H; Hatano, R; Hakamata, T
    BIogeochemistry, 97, 2-3, 141, 158, Mar. 2010, [Peer-reviewed], [Lead author]
    English, Scientific journal
  • Greenhouse Gas Budget in a Larch Forest with Low Atmospheric N Deposition in Hokkaido,Northern Japan
    HATANO R; NAKAHARA O; KAWAHARA S; KITAMURA S; KOIDE T
    Eurasian Journal of Forest Research, 10, 1, 71, 77, Hokkaido University Forests,EFRC, Mar. 2007
    English, Scientific journal, Article
  • Long-term trends in surface water quality of five lakes in Japan
    Yamada, T.; Inoue, T.; Fukuhara, H.; Nakahara, O.; Izuta, T.; Suda, R.; Takahashi, M.; Sase, H.; Takahashi, A.; Kobayashi, H.; Ohizumi, T.; Hakamata, T.
    Water, Air, and Soil Pollution: Focus, 7, 1-3, 259, 266, Springer Netherlands, 2007
    English, Scientific journal
  • Response to nitrogen loading in a P-limited larch forest ecosystem in Sapporo, Japan
    T. Koide; K. Sakai; S. Kawahara; Y. Usui; O. Nakahara; R. Hatano
    PHYTON-ANNALES REI BOTANICAE, 45, 4, 443, 450, 2005, [Peer-reviewed]
    English, Scientific journal
  • Effect of nitrogen deposition on CH4 uptake in forest soils in Hokkaido, Japan
    Morishita, T; Hatano, R; Nagata, O; Sakai, K; Koide, T; Nakahara, O
    SOIL SCIENCE AND PLANT NUTRITION, 50, 8, 1187, 1194, Dec. 2004, [Peer-reviewed]
    English, Scientific journal
  • Spatial variation in nitrogen deposition over five adjacent catchments in a larch forest
    Nakahara, O; Yamagami, T; Koide, T; Sakai, K; Hatano, R
    SOIL SCIENCE AND PLANT NUTRITION, 49, 5, 741, 746, Oct. 2003, [Peer-reviewed], [Lead author]
    Scientific journal
  • Adsorption, activity, and kinetics of acid phosphatase as influenced by selected oxides and clay minerals
    Shindo H; Watanabe D; Onaga T; Urakawa M; Nakahara O; Huang QY
    SOIL SCIENCE AND PLANT NUTRITION, 48, 5, 763, 767, Japanese Society of Soil Science and Plant Nutrition, Oct. 2002, [Peer-reviewed]
    English, Scientific journal, The effects of 3 oxides (Fe, Al, and Mn oxides) and 3 clay minerals (kaolin, montmorillonite, and allophane) on the adsorption and subsequent kinetic properties of acid phosphatase were compared. The amount of enzyme adsorbed by the oxides and clay minerals followed the order: montmorillonite ≫ kaolin > Mn oxide > Fe oxide > Al oxide ≫ allophane. The adsorption isotherms of the enzyme on the oxides and clay minerals, except for montmorillonite and allophane, fitted the Langmuir equation. The activity of the enzyme immobilized by the inorganic components studied was in the order of allophane > kaolin >Fe oxide >montmorillonite > Al oxide ≒ Mn oxide. Compared to the free enzyme, the V_max, K_m, and V_max / K_m values of the immobilized enzyme decreased, increased, and decreased, respectively. Among the oxides or clay minerals, the higher the ability of the inorganic components to adsorb the enzyme, the lower the value of the V_max / K_m ratio of the immobilized enzyme. These findings suggest that the catalytic efficiency of the enzyme complexes formed is determined by the adsorbability of the inorganic components for the enzyme.
  • Effect of forest fire on physico-chemical properties of Taiga soils in Yakutsk, Russia
    Kamide K; Hatano R; Nakahara O; Sawamoto T; Takahashi K; Desyatkin RV
    Proceedings of the ninthe symposium on the joint Siberian permafrost studies between Japan and Russia in 2000, 104, 111, 2001
    English
  • Model of cation adsorption on allophanic andisols - II. Description of mono-component adsorption
    Nakahara O
    SOIL SCIENCE AND PLANT NUTRITION, 46, 1, 21, 29, Japanese Society of Soil Science and Plant Nutrition, Mar. 2000, [Peer-reviewed]
    English, Scientific journal, The model introduced in the previous report (Nakahara 2000: Soil Sci. Plant Nutr., 46, 11-20) described cation adsorption on Choyo B soil satisfactorily. The optimized parameters, r_, n_, and d_, are physically sound. When the total number of cations per one allophane particle n_M is less than 1.0, major type of cation adsorbed was in the form of diffuse ion swarm. On the other hand, when n_M was higher than 1.0, the fraction of surface complexes increased with n_M. The reason for the suitability of the Freundlich-type adsorption isotherm for application to the cation adsorption on allophane was clarified.
  • Model of cation adsorption on allophanic andisols - 1. Theory and algorithm
    Nakahara O
    SOIL SCIENCE AND PLANT NUTRITION, 46, 1, 11, 20, Japanese Society of Soil Science and Plant Nutrition, Mar. 2000, [Peer-reviewed], [Lead author]
    English, Scientific journal, A new model of cation adsorption on allophanic Andisols was proposed. This model assumes that cations are adsorbed in the internal space of the hollow spherical ball of allophane either in the form of a diffuse ion or through the formation of surface complexes with SO- groups arranged on the inner surface swarm. The distinctive characteristics of this model is that the mean-field approximation was not adopted, but the Coulomb potential among charged particles was directly evaluated by using the primitive restricted model (Valeau and Cohen 1980: J. Chem. Phys., 72, 5935-5941) and the grand canonical Monte Carlo (GCMC) simulation. This report introduces the theory and the algorithm of the GCMC simulation.
  • Analysis of Vanselow, Gapon, and Davis selectivity coefficients based on simple lattice statistics
    Nakahara O
    SOIL SCIENCE AND PLANT NUTRITION, 45, 1, 225, 229, Japanese Society of Soil Science and Plant Nutrition, Mar. 1999, [Peer-reviewed], [Lead author]
    English, Scientific journal, Simple lattice statistics was applied to formulate the monovalent-bivalent cation exchange reaction on lattice surfaces. The Davis and Gapon selectivity coefficients K_D and K_G could be derived for two-dimensional lattices with different reactions between bivalent cations and exchange sites. On the other hand, the Vanselow Selectivity coefficient K_v could not be derived for two-dimensional surfaces, but was found to be suitable for one-dimensional arrays of exchange sites. These results suggest that the use of K_v should be restricted to one-dimensional exchangers like linear polyelectrolytes and humic substances, while KD is suitable for general purposes.
  • Theoretical Study on Cation Adsorption on Andisols
    Nakahara O.
    Japanese Journal of Soil Science and Plant Nutrition, 69, 3, 245, 246, Japanese Society of Soil Science and Plant Nutrition, 1998
    Japanese
  • 奨-4 火山灰土壌の陽イオン吸着の理論化(日本土壌肥料学会奨励賞)
    中原 治
    日本土壌肥料学会講演要旨集, 44, 245, 245, 一般社団法人日本土壌肥料学会, 1998
    Japanese
  • 4-13 Freundlich等温吸着式の理論的基礎(第3報) : 去年のモデルはアロフェンには当てはまりませんでした(4.土壌鉱物)
    中原 治
    日本土壌肥料学会講演要旨集, 43, 27, 27, 一般社団法人日本土壌肥料学会, 1997
    Japanese
  • Reconsideration of theoretical basis of Freundlich adsorption isotherm equation .2. Approximative derivation
    Nakahara O
    SOIL SCIENCE AND PLANT NUTRITION, 42, 1, 51, 61, Japanese Society of Soil Science and Plant Nutrition, Mar. 1996, [Peer-reviewed], [Lead author]
    English, Scientific journal, I constructed a modified surface complexation model that leads to the Freundlich isotherm approximately. The derivation of the Freundlich isotherm equation is based on the assumption that cations and anions are adsorbed onto the same surface simultaneously. This situation results in the formation of attractive forces between adsorbed cations and anions on the surface. Then the electrostatic energy of the surface should decrease with the increase of adsorption provided that the amount of the ion under consideration is smaller than that of the oppositely charged ion. By using the quadratic approximation theorem, we can approximate this electrostatic energy of quadratic polynomial : E^_(n)=An^2-Bn+C, by the following function : E^_(n)^=D(nln(n/E)-n)+F, where n is the number of ions adsorbed, A, B, C, D, and E are constants with a positive value. Using this equation as the approximated electrostatic energy, we can deduce the Freundlich isotherm easily. This model provides a theoretical basis to the fact that heavy metal adsorption on the edge surface of layer silicate minerals often follows the Freundlich adsorption isotherm equation.
  • Reconsideration of theoretical basis of Freundlich adsorption isotherm equation .1. The problem
    Nakahara O
    SOIL SCIENCE AND PLANT NUTRITION, 42, 1, 41, 49, Japanese Society of Soil Science and Plant Nutrition, Mar. 1996, [Peer-reviewed], [Lead author]
    English, Scientific journal, I discussed the problem we face if attempts are made to derive the Freundlich isotherm equation as an electrostatic adsorption model like the surface complexation models. To derive this equation we need the following electrostatic energy : E^_=C(nln(n/D)-n)+E, where n is the number of ions adsorbed, and C, D, and E are constants with a positive value. This equation requires that when the number of ions adsorbed is relatively small, there must be attractive forces among adsorbed ions on the surface. The partial derivative of this equation : (∂^/∂n)_=Cln(n/D), diverges to minus infinite at the limit n→0. This divergence requires that the attractive forces among adsorbed ions diverge to infinite at the limit n→0. To derive the Freundlich isotherm equation, we need to reveal the mechanism that leads to the requirements described above.<
  • 4-7 Freundlich等温吸着式の理論的基礎(第二報) : Monte Carloシミュレーションを用いた探索(4.土壌鉱物)
    中原 治
    日本土壌肥料学会講演要旨集, 42, 25, 25, 一般社団法人日本土壌肥料学会, 1996
    Japanese
  • 腐植質土壌の陽イオン吸着の表面錯形成モデル(第1報)K^+, Ca^<2+>の吸着の記述
    中原 治; 和田 信一郎
    日本土壌肥料学雑誌, 67, 1, 90, 91, 一般社団法人 日本土壌肥料学会, 1996
    Japanese
  • 腐植質土壌の陽イオン吸着の表面錯形成モデル(第2報)K^+-Ca<2+>イオン交換平衡の予測
    中原 治; 和田 信一郎
    日本土壌肥料学雑誌, 67, 1, 91, 91, 一般社団法人 日本土壌肥料学会, 1996
    Japanese
  • SURFACE COMPLEXATION MODEL OF CATION ADSORPTION ON HUMIC SOILS .2. K+-CA2+ EXCHANGE EQUILIBRIA
    Nakahara Osamu; Wada Shin-Ichiro
    NAKAHARA O;WADA SI, 41, 4, 671, 679, Japanese Society of Soil Science and Plant Nutrition, Dec. 1995, [Peer-reviewed], [Lead author]
    English, Scientific journal, We evaluated the ability of a new surface complexation model "multi-layer model" of Nakahara and Wada (1995: Soil Sci.Plant Nutr., 41, 659-669) to predict the K^+-Ca^<2+> exchange equilibria on a humic Andisol. Under the assumption that the relative permittivity of the interfacial region is constant at any points, we could calculate the K^+-Ca^<2+> exchange equilibrium conditions using the four parameters previously obtained from K^+ and Ca^<2+> adsorption data. The model predicted the variation of the exchange selectivity coefficient of Vanselow (K_V) and the pH of the bathing solutions as a function of the equivalent fraction of adsorbed K^+ satisfactory. We concluded that our model can be used for the calculation of the chemical equilibria of soil solutions of humic soils.
  • SURFACE COMPLEXATION MODEL OF CATION ADSORPTION ON HUMIC SOILS .1. K+ AND CA2+ ADSORPTION
    NAKAHARA O; WADA SI
    SOIL SCIENCE AND PLANT NUTRITION, 41, 4, 659, 669, Japanese Society of Soil Science and Plant Nutrition, Dec. 1995, [Peer-reviewed], [Lead author]
    English, Scientific journal, We constructed a new surface complexation model designated as "multi-layer model" that describes the cation adsorption on humic soils. This model is different from the existing surface complexation models in three ways: (1) we assumed the existence of a cylindrical surface, instead of a planar surface, as a model of humic polymers, (2) we ignored the diffuse ion swarm formation and assumed that all the adsorbed ions are held by the formation of outer-sphere surface complexes, and (3) we assumed that different ions are adsorbed on different planes. The applicability of the model to describe the experimental data on acid-base properties of a humic soil was satisfactory.
  • K-CA EXCHANGE EQUILIBRIA ON HUMIC AND ALLOPHANIC ANDISOLS
    NAKAHARA O; WADA SI
    SOIL SCIENCE AND PLANT NUTRITION, 41, 1, 167, 172, Japanese Society of Soil Science and Plant Nutrition, Mar. 1995, [Peer-reviewed], [Lead author]
    English, Scientific journal
  • 4-7 Freundlich等温吸着式の理論的基礎【第一報】 : 問題の本質はどこにあるのか?(4.土壌鉱物)
    中原 治
    日本土壌肥料学会講演要旨集, 41, 30, 30, 一般社団法人日本土壌肥料学会, 1995
    Japanese
  • An Electrostatic Model of Cation Adsorption on Humic Soils. 1 : K^+ and Ca^<2+> Adsorption
    NAKAHARA Osamu; WADA Shin-Ichiro
    Japanese Journal of Soil Science and Plant Nutrition, 66, 4, 388, 395, Japanese Society of Soil Science and Plant Nutrition, 1995
    Japanese, We proposed a new multi-layer surface complexation model that describes cation adsorption on humic Andisols. This model is different from the existing surface complexation models in three ways : (1) we assumed a cylindrical surface instead of a planar surface as a model of humic polymers, (2) we ignored the diffuse ion swarm formation and assumed that all the adsorbed ions are held by the outer-sphere surface complexes formation, and (3) we assumed that different ions are adsorbed on different planes. The applicability of the model to describe the experimental data is satisfactory.
  • 2 SIMPLE ISOTHERMS DESCRIBING CATION ADSORPTION ON ANDISOLS
    NAKAHARA O
    SOIL SCIENCE AND PLANT NUTRITION, 40, 1, 83, 94, Mar. 1994, [Peer-reviewed], [Lead author]
    English, Scientific journal
  • CA2+ AND MG2+ ADSORPTION BY AN ALLOPHANIC AND A HUMIC ANDISOL
    NAKAHARA O; WADA SI
    GEODERMA, 61, 3-4, 203, 212, Mar. 1994, [Peer-reviewed], [Lead author]
    English, Scientific journal
  • CaCl_2とMgCl_2溶液中における火山灰土壌へのCl^-吸着
    中原 治; 和田 信一郎
    日本土壌肥料学雑誌, 65, 1, 103, 103, 一般社団法人 日本土壌肥料学会, 1994
    Japanese
  • 火山灰土壌の陽イオン吸着を記述する2つの簡単な等温吸着式
    中原 治
    日本土壌肥料学雑誌, 65, 2, 223, 223, 一般社団法人 日本土壌肥料学会, 1994
    Japanese
  • 3-8 腐植質火山灰土壌のイオン交換平衡予測モデル(3.土壌鉱物および膠質複合体)
    中原 治; 和田 信一郎
    日本土壌肥料学会講演要旨集, 40, 24, 24, 一般社団法人日本土壌肥料学会, 1994
    Japanese
  • CL- ADSORPTION ON ANDISOLS FROM CACL2 AND MGCL2 SOLUTIONS
    NAKAHARA O; WADA SI
    SOIL SCIENCE AND PLANT NUTRITION, 39, 4, 645, 652, Japanese Society of Soil Science and Plant Nutrition, Dec. 1993, [Peer-reviewed], [Lead author]
    English, Scientific journal, To evaluate the effect of coexisting cations on Cl^- adsorption in variable-charges soils, we measured the Cl^- adsorption from CaCl_2 and MgCl_2 solutions on two Andisols as a function of the pH and electrolyte concentration, and compared the results with the adsorption from NH_4Cl and NaCl solutions. For the Choyo B soil in which allophane and imogolite are the dominant exchangers, the Cl^- adsorption from NaCl, NH_4Cl, and MgCl_2 solutions was only determined by the pH + pCl values of the bathing solutions. In the CaCl_2 solutions, however, the Cl^- adsorption deviated positively from the relationship obtained in using the NaCl, NH_4Cl, and MgCl_2 solutions. We considered that this deviation reflected the CaCl^+ ion-pair adsorption on negatively charged sites. In a 50 mmol L^<-1> CaCl_2 solution at pH = 7.1, the estimated CaCl^+ ion-pair adsorption amounted up to about 10% of the adsorbed Ca^<2+> and 56% of the adsorbed Cl^- on a mol kg^<-1> basis. In the lower pH range (<6.5), however, the CaCl^+ adsorption was negligible. Daikanbo A soil whose exchanger consisted of Al-humus complexes showed a net negative adsorption of Cl^-. These results suggest that the contribution of MCl^+ (M=Ca or Mg) complexes was not significant. The exclusion volume was relatively constant irrespective of the pH and electrolyte concentration. We attributed these results to the Donnan effect.
  • SOLUBLE SILICA IN A TEPHRA-DERIVED SPODOSOL IN THE MOUNTAINOUS REGION OF CHICHIBU, JAPAN
    SAKAGAMI K; NAKAHARA O; HAMADA R
    SOIL SCIENCE AND PLANT NUTRITION, 39, 1, 139, 151, Japanese Society of Soil Science and Plant Nutrition, Mar. 1993, [Peer-reviewed]
    English, Scientific journal, Si sorption and release characteristics of a tephra-derived Spodosol in the mountainous region of Chichibu, Japan, were studied, and cation-exchange resin extraction of protoimogolite was tested. The upper compartment and the lower compartment of the Bhs/Bs interface differed considerably in their reactivity for H_4SiO_4. The upper compartment (Oa, E, Bhs1, and Bhs2 horizons) showed a weak affinity for H_4SiO_4.These horizons gave zero-order H_4SiO_4 release, and the initial stage of H_4SiO_4 release was well described by the parabolic diffusion law. These results suggest that the upper profile contains a large amount of free Si and acts as a Si pool. Especially, the Oa horizon did not show any H_4SiO_4 adsorption in a 0-3 mmol L^<-1> H_4SiO_4 solution, and gave a much larger H_4SiO_4 release rate. The lower compartment (Bs1 and Bs2 horizons) which contains allophane/imogolite showed a strong affinity for H_4SiO_4. The H_4SiO_4 release rate of these horizons was described by the Elovich equation. These findings suggest that in the lower profile, the H_4SiO_4 concentration is well controlled by the reaction with surface Al-OH groups of allophane/ imogolite and hydroxy-interlayer minerals. Cation-exchange resin, Chelex 100, extracted a very small amount of Si from only the Bhs1 and Bhs2 horizons, suggesting that a trace amount of protoimogolite accumulated in these horizons. The protoimogolite was probably complexed with humic substances.
  • 3-11 火山灰由来土壌によるCa、Mgイオン吸着(3. 土壌鉱物および膠質複合体)
    中原 治; 和田 信一郎
    日本土壌肥料学会講演要旨集, 38, 27, 27, 一般社団法人日本土壌肥料学会, 1992
    Japanese
■ Other Activities and Achievements
■ Books and other publications
■ Syllabus
  • 実験計画法, 2024年, 学士課程, 農学部
■ Research Themes
  • Effects of P limitation on nutrient cycling intemperate forests
    Grants-in-Aid for Scientific Research
    2009 - 2011
    NAKAHARA Osamu; SHIBUYA Masato
    We examined nutrient limitation in 26 stands of larch forest onvolcanic parent material deposited 300-20,000 y BP at Mt. Shirahata, Sapporo, Japan.Root-ingrowth bioassay showed that of the 26 stands examined 13were N limited,3were Plimited, and 10 were N and P colimited. Nitrogen limitation was common in stands with afoliar N:P ratio<16. In stands with foliar N:P ratio>16, colimitation by N and P dominated,but P limitation was observed at three stands.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, 21580073
  • Modeling of nitrate runoff from agricultural watershed
    Grants-in-Aid for Scientific Research
    2004 - 2005
    NAKAHARA Osamu
    In Shibetsu watershed that is located in eastern Hokkaido, about 25% of net nitrogen input (NNI) was nitrified into nitrate form and discharged into rivers without removal by plant uptake and denitrification. The nitrate runoff causes eutrophication in coastal and brackish area and often results in degradation of environment of these area and severe damage on fishery. Therefore, we need to establish the management to minimize the nitrate runoff.
    In this study, we aimed to make model that predicts rate of nitrate removal in deeper soil horizon in two dimension with watershed scale. In this model we assumed that the nitrate removal reaction (mainly denitrification reaction) mediated by microbes obey first order reaction. The time term in this kinetic reaction was replaced by the ratio of distance between the point of nitrogen load and nearest river by using Hydrology Extension in ArcGIS 9.0. From field observation, we found empirical rule that nitrate concentration in rivers negatively correlated with slope of rivers.
    This model explained 94% of spatial variation in nitrate concentration in rivers in Shibetsu watershed. The predicted rate of nitrate removal by denitrification amounted from several percent to fifty percent. The rate of removal depended on size of watershed and average slope in the watershed.
    Further effort is needed to give sound theoretical proof to the empirical relationship between nitrate concentration in rivers and the slope of the river. In this study, we tried to prove the relationship by using Manning's law and Leopold's empirical law but failed to give final answer.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, 16580042
  • Effect of nitrogen deposition on fluxes of green house gases in a forest ecosystem
    Grants-in-Aid for Scientific Research
    2003 - 2005
    HATANO Ryusuke; NAKAHARA Osamu; HATA Hiroshi; SHIBUYA Masato
    Nitrogen deposition has been known to affect emission and absorption of green house gases in forest ecosystems. Nitrogen deposition enhances nitrous oxide emission from forest soils and inhibits methane emission into forest soils. Nitrogen deposition might enhance or diminish forest growth and CO_2 sequestration. Most researches, however, focus on nitrogen-saturated forests receiving high deposition of nitrogen (DIN > 10 kgN ha^<-1> y^<-1>), and we need more information on the effect of nitrogen deposition on green house gases fluxes in forests receiving low nitrogen deposition (DIN < 10 kgN ha^<-1> y^<-1>). IPCC proposed the concept of 'Global Warming Potential' (GWP) as a comprehensive measure of effect of ecosystem biogeochemical processes on global warming. Previous studies mainly focused on one of these green house gases, e.g., carbon dioxide, nitrous oxide and methane. Very few studies reported total effect of these gases or GWP of forest ecosystems. The purpose of this study is to reveal the effect of very low nitrogen deposition on GWP in a larch forest. We studied at five sites in larch forest in Mt. Shirahata, Sapporo city, northern Japan. N_2O emission and CH_4 absorption at the surface of soil/snowpack were measured with closed chamber method. CO_2 sequestration was estimated with measurement of tree heights and diameters at breath height, allometric equation, and microbial respiration measured by incubation of moist soils in laboratory.
    Nitrogen deposition during no-snow season ranged 0.8 〜 1.8 kgN ha^<-1> y^<-1>. Annual CH_4 absorption ranged 5 〜 7 kgC ha^<-1> y^<-1> and showed no correlation with nitrogen deposition. But comparison of our result with literature data suggested that high CH_4 absorption in this study site was caused by very low nitrogen deposition that is known to inhibit CH_4 absorption. Nitrous oxide emission in this study was classified as background type emission because N_2O emission showed no correlation with soil temperature and soil moisture. Background type N_2O emission has been believed not to affected by nitrogen deposition. Annual N_2O emission ranged 0.02 〜 0.09 kgN ha^<-1> y^<-1>. Accumulated N_2O emission during no-snow season showed positive correlation to nitrogen deposition during now-snow season. Comparison of our results with literature data on background type N_2O emission suggested that even background type N_2O emission is affected by nitrogen deposition. Net ecosystem productivity (NEP) ranged 0.2 〜 2.1 tC ha^<-1> y^<-1>. NEP showed positive correlation to nitrogen deposition during no-snow season. Calculation of GWP revealed that CO_2 sequestration by forest vegetation was largest component in GWP in this study site ; contribution of N_2O emission and CH_4 absorption to GWP was negligible. In summary, nitrogen deposition has a negative effect on global warming and tree growth enhancement by nitrogen deposition has much larger role than enhanced N_2O emission and reduced CH_4 absorption by nitrogen deposition.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 15380045
  • 森林生態系における窒素動態-無機態窒素と有機態窒素の樹木の窒素吸収への寄与
    科学研究費助成事業
    2002 - 2003
    中原 治
    札幌市都市環境林白旗山の5つの小流域において、窒素循環をモニタリングによって測定した。A層の土壌溶液の溶存無機態窒素濃度は最高3.11ppm、最低0.02ppm、平均0.78ppmで推移した。降水量から河川流量の差引した結果、生育期間に5流域の平均で約300mm程度の蒸発散があり、この間にマスフローで運ばれた溶存無機態窒素(NO3+NH4)は2.4kgNha-1yr-1となった。これは1年間の窒素吸収量41.8kgNha-1yr-1のわずか5.7%程度であった。この結果は、マスフローによる窒素吸収の寄与が極めて小さい事を意味する。窒素吸収量の94%は拡散による吸収という結果であるが、それが陽イオン交換基に保持されたNH4か?、有機態窒素であるか?は本研究のデータからは判別できないが、有機態窒素の寄与が十分にあり得ると推察した。0層からA層への窒素フラックスが年間で3.5kgNha-1yr-1しかなく、DON(溶存有機態窒素)とDIN(溶存無機態窒素)の寄与がほぼ半々であった。こうした結果は、0層からの直接的な窒素吸収がない限り説明できない。0層からの吸収が主体であればNH4での吸収の可能性がかなり低くなるからである。
    日本学術振興会, 若手研究(B), 北海道大学, 14760035
  • 環境汚染物質の吸着現象の分子シミュレーション
    科学研究費助成事業
    2000 - 2001
    中原 治
    グランドカノニカルアンサンブルを用いたアルゴリズムの大枠が完成した。ソースコードはC言語を用いて記述し、これをCodeWarriorでコンパイルした。これにRPポテンシャ関数を組み込み、アロフェンを模した中空状粒子内での陽イオン吸着をシミュレーションした。アロフェンは火山灰土壌に特有の非結晶性ケイ酸アルミニウム鉱物であるが、その陽イオン吸着の物理化学的側面が、未だに明らかにされていない。アロフェンの陽イオン吸着は表面錯形成モデルでは記述できず、Freundlich式が有効であるが分かっている。しかし、その理論的基礎はまったく知られていなかったため、このシミュレーションモデルの有効性を評価するのには最適だと考えられる。このアルゴリズムに滑降シンプレックス法を組み込み、吸着を記述するのに必要なパラメータの最適化を行うと、中空粒子の内径(2.2nm)や表面水酸基数(nTOT=62)といった基本的なパラメータが、ほぼ実際のアロフェンで予測される値に収束した。そして吸着量のpHによる変化も非常に性格に予測した。さらにFreundlich式で記述できない領域を予測たため、この領域で吸着データを採取した。その結果、実測データはこの理論的予測を正確に一致した。粒子内部のイオンの分布を調べると、アロフェン1個当たり、吸着したイオンの数が1個と2個の間で、全く様式が異なることが分かった。2個以上ではお互いに反発が強くなり、これが、表面錯形成モデルの平均場近似で予測できない原因となることが判明した。この結果は、本シミュレーションモデルが、吸着平衡の予測に非常に有効であることを示している。
    日本学術振興会, 奨励研究(A), 北海道大学, 12760039
  • 土壌コロイドの表面化学的性質とその出現のダイナミクス
    科学研究費助成事業
    1999 - 1999
    足立 泰久; 石田 智之; 中原 治; 溝口 勝; 南條 正巳; 中石 克也
    本研究の全体像は、(1)土壌コロイドの表面化学的な性質の解明とそのモデル化、(2)汚染物質のキャリアとしてのコロイドの水理学的モデル化、(3)水文学的スケールからみたモデル化に要求される視点、の3つのスキームに区分される。以下、それぞれのスキームごとに調査検討した内容を本研究のカテゴリーである企画調査の観点より要約する。
    (1)の論点は以下の2つである。第一の論点は、移動現象を記述するうえから化学物質の土壌表面に対する吸着、収着、核形成、表面沈殿等の集積現象のモデル化に必要性を明確にした点にある。第二の論点は、力学特性や物質移動特性の解析に表面化学的立場から足がかりを与えるための視点を特に表面水の物理化学的性質の観点から明確にすることの必要性を明らかにした点にある。これらの両者に関連する研究は、今後飛躍的に発展する潜在性を有していると分析された。
    (2)のカテゴリーでは熱力学と水理学の両者を駆使したキャリア自体の運動の解析が必要であるが、運動法則の第一原理に基づくモデルの構築には限界があり、第1スキームで得られる情報を前面に出せるような大胆なモデル化が有効と考えられる。ここでは特にその試みとして、固体の体積分率から解析の長さスケールを導いて解析する方法、粒子間接点数に着目する方法、さらにはStern層の横方向の移動度を解析する方法などを提案し、その実用性を討議した。
    (3)では環境に対する負荷という点より、土壌浸食に伴って移動する栄養塩や農薬の問題と、放射性物質等の有害な重金属が地層中をコロイドにくっついて移動する問題とが、キャリアとしてのコロイド粒子の問題に水文学的スケールで関わっていることを明確にし、これらの問題を扱う体系を明らかにした。
    日本学術振興会, 基盤研究(C), 筑波大学, 11896007
  • Effects of physico-chemical properties of rhizosphere soils on uptakes of nutrients by rice.
    Grants-in-Aid for Scientific Research
    1997 - 1998
    EGASHIRA Kazuhiko; NAKAHARA Osamu; WADA Shin-Ichiro
    Rhizobox was constructed in which soil solution samplers nad platinum electrodes were inserted in each compartment. Rice plants were grown in this rhizobox. Allophanic and smectitic soils were used for this experiment to investigate effects of physico-chemical change of rhizosphere soil by the observation of the differences between thses soils with distinct physicochemical properties. Soil solutions of different distances from rice root were collected every week. PH, NH4, Fe(ll), organic C, inorganic C concentration were measured for these solutions.
    The ways of NH4 uptake were different in allophanic and smectitic soils. In smectitic soil, in both phase I and phase II, uptake by mass flow was the major N uptake mechanism. This result was contradict with ordinary explanation by which NH4 uptake in phase II is explained by diffusive uptake. In phase II, the decrease in CEO by pH reduction enhanced NH4 mobility around rice root.
    In allophanic soil, in phase I, uptake by mass flow was the major N uptake mechanism, but in phase II uptake by diffusion was the major N uptake mechanism. Our results indicated that in phase I N accumulation into organic N proceeded and in phase It mineralization of the organic N enhanced NH4 uptake by rice root.
    Next, pecial rhizobox was constructed to take subsamples from rhizosphere during growth of rice plant. Organic N profiles in rhizosphere soils were distinct between allophanic and smectitic paddy soils. Buf by rapid decrease in hydro-conductivity of rhizobox did not allow to distinguish the detailed mechanism of N uptake in AIlophanic paddy soil.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), KYUSHU UNIVERSITY, 09460039