中国边缘海沉积有机质来源及其碳汇意义

Sources of Sedimentary Organic Matter in China Marginal Sea Surface Sediments and Implications of Carbon Sink

中国边缘海(本文特指渤海、黄海和东海,不包括南海)是陆源和海源有机质的重要碳汇。总有机质指标和生物标志物的结果显示,表层沉积物中陆源有机质高值集中在近岸尤其是河口附近;海源有机质在陆架海盆处有高值,受控于海洋生产力和沉积环境。利用多参数指标对表层沉积物中不同来源和不同年龄有机质的贡献比例估算的结果显示,我国边缘海的有机碳埋藏量约13 Mt/a,占全球边缘海沉积物有机碳埋藏量(~138 Mt/a)的~10%,其中陆源有机质的碳埋藏量(3.9 Mt/a)占全球边缘海沉积物陆源有机质埋藏量的~7%。若假定陈化土壤有机质和古老有机质主要是陆源物质,则非现代有机质的碳埋藏量为~6Mt/a,占我国边缘海总有机质碳埋藏量的~46%,与全球边缘海沉积物中陆源有机质的平均比例(44%)相当。这些结果表明我国边缘海在全球海洋碳循环中具有重要地位。本文利用已发表的文献数据,总结和归纳了中国边缘海沉积有机质来源及其碳汇意义。

China marginal seas （CMS, including the Bohai Sea, the Yellow Sea, the East China Sea）, are a significant sink for both terrestrial organic matter （TOM） and marine OM （MOM）. Both the sources and distributions of OM in China marginal seas have been affected by rapid climate changes and anthropogenic activities over the last 60 years. The total organic carbon （TOC） proxies and biomarker results of surface sediments indicated that higher percentage of TOM （%TOM） occurred near coastal re- gions and especially near river mouths such as the Yellow River Estuary, the old Huanghe Estuary and the Changjiang River Estuary. Higher percentage of MOM values were found in shelf sea basins, con- trolled by the marine primary production and depositional settings. Quantitative estimates based on both TOC and biomarker proxies with binary or ternary models revealed that total a sequestration of 13 Mt/a TOC buried in CMS （~ 10% of global continental margin sediments） and burial TOM accounted for -7% that of global continental margin sediments. If we assumed non-modern OM （including pre-aged and fossil OM） was mainly terrigenous, then the percentage of non-modern OM in CMS was -46%, comparable to the %TOM （44%） of global continental margin sediments. The preliminary carbon budg- et in the CMS indicated that it plays an important role in the global marine carbon cycle. This paper sun- maries the sources of sedimentary organic matter in of carbon sink using published data. china maginal sea surface sedments and implications