ORGANIC GEOCHEMISTRY RELATED TO THE GAS HYDRATE-BEARING SEDIMENTS IN THE OKHOTSK SEA

Abstract

This study is conducted to provide the organic geochemical information related to the origin and composition of sedimentary organic matter, and to investigate the activity of microorganisms using 13C-glucose addition experiment. The research cruise (R/V, Lavrentyev) was carried out at 9 stations in the Okhotsk Sea from June 1 to June 7, 2006. The results of C/N ratios and stable isotope ratios of organic carbon and total nitrogen in the sediments indicated that most of the hydrate-contained sedimentary organic matter derived from marine phytoplankton but a non-hydrate-contained sedimentary organic matter only at LV39-29H seems to be remarkably affected from terrestrial plants. The finding is supported by high concentrations of long-chain odd number free hydrocarbons (C27, C29, C31).