Studies on diagenetic change of chemical and isotopic compositions of marine organic matters during sedimentation.

采集东海、日本海和日高海槽沉积有机质和悬浮有机颗粒，分析其稳定碳、氮同位素、木质素酚类和烃类等生物标志物。颗粒<13><15>物从表层向深层沉降过程中，悬浮物的~（1C）和~（1 N）分别从-20 ~-28* 和4 ~ 10* 变化，说明颗粒有机物在深层的降解可能伴随着同时发生的同位素分馏，这可能是由于有机物的优先分解或同位素歧视所致。尽管这种同位素组成沿着水深变化，但混合层中的颗粒物对控制沉降颗粒和表层沉积物的同位素组成起着重要作用。研究发现，悬浮物、沉降颗粒物和表层沉积物中碳和氮的同位素组成发生了变化。结果表明，木质素酚是评价陆源有机质向海相沉积有机质转化的基本指标。然而，得出的结论是，Hedges和Mann（1979）定义的木质素λ将受到海洋生产力等当地因素的影响，因此<13>应针对每个地点定义λ和8^ C（TOC）之间的关系。

Sedimentary organic matter and suspended organic particles were collected from the East China Sea, Japan Sea and Hidaka trough, and were analyzed for biomarkers such as stable carbon and nitrogen isotopes, lignin phenols and hydrocarbons. The ^<13>C and ^<15>N of suspended matter changed from -20 to -28*, and 4 to 10*, respectively during settling of particles from surface to deep layr, meaning that degradation of partculate organics in the deep layr might follow simultaneous isotopic fractionation due to preferencial decomposition of organic compounds or isotopic discrimination. In spite of such isotopic change along the water depth, it is emphasized that the particulate matter in themixing layr would play an important role to control isotopic composition of settling particles and surface sediment. We found that there is an isotopic shift among suspended matter, settling particle and surface sediment for both carbon and nitrogen. Our results showed that lignin phenol is basically useful proxy to evaluate cotribution of terrestrial organic matter into the marine sedimentary organic matter. However, it was concluded that lignin lambda which has been defined by Hedges and Mann (1979) would be infuluenced by local factors such as marine productivity so that the relationship between lambda and 8^<13>C (TOC) should be defined for each locations.