Geochemical study on the composition and degradation processes of organic matter during early diagenesis: A case study in the sediments from the offshore area of the western part of Hokkaido, Japan.

摘要

Total organic carbon, nitrogen, sulfur, #delta#~13C,n-alkane, n-fatty acid, n-alcohol, and n-hydroxy acid were analyzedwithin surface sediments and core collected from the offshore areaof the eastern part of Hokkaido. The accumulation and degradationprocesses of organic mater are discussed on the distribution of theorganic constituents.Organic constituents of the surface sediments were generalyhigher in Okusiri basin and lower in Matsumae plateau. Organiccontents in the sediments were consistent with the grain size ofsediments, that is, organic contents were larger in clay than in silt.The facts that higher ratios of C/N, lower ratios of L/H, smallervalues of #delta#~13C suggest the larger suppry of terrestrialhigher plants in Okushiri basin. Though L/H rations and CPI of n-alkane and n-fatty acid were scattered in the surface sediments, theaverage values were higher in n-fatty acid than in n-alkane. It isconceivable that the precursor and preservation processes of n-alkane are different from those of n-fatty acid.