ANALYSIS OF GEOCHEMICAL CYCLES OF NITROUS OXIDE AND METHANE THROUGH ISOTOPE TRACERS

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(1) Nitrogen isotope ratio in nitrous oxide is found to be not determined by equilibrium with sea water, fresh water, and nitrogen molecule in the atmosphere, but by kinetic isotope fractionation during production and consumption. Oxygen isotope ratio is higher than 40* with areal variation, suggesting oxygen isotope exchange during or after production.(2) Carbon isotope ratio in methane is mainly determined by kinetic isotope fractionation during production. Whereas, hydrogen isotope ratio is varing with latitude, suggesting the reflection of environmental water during production. Carbon-14 analysis with accelarator mass spectrometer is uuder preparation, some of the data has been taken.(3) Environmental water, which is closely related to oxygen isotope ratio in N_2O and hydrogen isotpe ratio in CH_4, shows latitudinal gradient. Hydrogen isotope ratio in CH_4 and water are closely related with each other.(4) Gaschromatograph equipped with electron capture detector was not introduced because of the lack in royal settlement. I have gotten the license of ratiation protection manager and rule for the protection of radiation hazard has been settled. So that, it will be introduced in the next fiscal year.