Isotope Biogeochemical Structure of Biosphere-New Paradigm

京都大学生态研究中心已建立了碳氮稳定同位素比值测量系统，该系统在同位素生态学领域处于世界中心和领先地位。采用气相色谱/燃烧/同位素比质谱仪（GC/C/IRMS）建立了淡水中甲烷δ ^<13>C和总无机碳δ ^<13>C的在线测量系统。成功绘制了三角洲<@D115@>D1N (NO<@D23@>D2<@D1-@>D1) -<@D7[NO<@D23@>D2](/)Cl@>D7同位素图，用于评价森林生态系统的氮动态。绘制了三角洲<@D113@>D1C (CH<@D24@>D2) -三角洲D （CH<@D24@>D2）图，探讨了不同类型水田湿地的甲烷生成机制。研究了琵琶湖和贝加尔湖食物网的同位素生物地球化学结构。在原位条件下阐明了固氮在白蚁-原生动物-固氮细菌组合中的重要性。在森林生态系统中，建立了光照强度与三角洲^<13> c叶片垂直趋势之间的关系。

A system for the measurement of carbon and nitrogen stable isotope ratios has been established in Center for Ecological Research, Kyoto University, which is one of the central and leading place in the field of Isotope Ecology in the world.On line measurement system to determine methane delta ^<13>C and total inorganic carbon delta ^<13>C in fresh waters has been developed by using a gas chromatograph/Combustion/Isotope Ratio Mass Spectrometer (GC/C/IRMS) .A delta <@D115@>D1N (NO<@D23@>D2<@D1-@>D1) -<@D7[NO<@D23@>D2](/)Cl@>D7 isotopic map was successfully conpleted for assessing the dynamics of nitrogen in a forested ecosystem. A delta <@D113@>D1C (CH<@D24@>D2) -delta D (CH<@D24@>D2) map was also made for assessing the production mechanisms of methane in various kinds of wetland involving paddy fields.Isotope biogeochemical structures of a food web in Lake Biwa and Lake Baikal was obtained. Importance of N_2 fixation in a termite-protozoa-N_2 fixing bacteria association was clarified under in-situ conditions.In forested ecosystems, a relationshi between light inlensity and a vertical trend of leaf of delta ^<13> Cwas established.