东海沉积物中微生物标志物GDGTs年代际变化及来源

甘油双烷基甘油四醚(Glycerol Dialkyl Glycerol Tetraethers,GDGTs)是近几年来新发现的一类生物标志化合物,基于GDGTs的各种指标以其在指示物质来源以及海洋和陆地古温度重建等方面显示出的巨大应用潜力,逐渐成为古海洋学、古湖沼学和古气候学研究的重要工具。对采自东海陆架区的DH5-1站位(29°28.118′N、123°06.639′E,水深63.5m)的柱状沉积物样品进行了总有机质和GDGTs分析,研究了GDGTs化合物在东海陆架区柱状沉积物样品中的含量和沉积通量变化,并利用δ13 C、C/N以及基于GDGTs化合物的BIT指标讨论了该海区近150年来沉积有机质的来源变化。结果显示,近百年来东亚冬季风的增强,加强了冬季闽浙沿岸流对长江口沉积物的搬运,使得该海区陆源输入量呈增加趋势,但20世纪80年代以来,人类活动的加剧导致营养盐输入的增加,使得海洋生产力提高,沉积有机质中陆源有机质比例下降。

DECADAL CHANGES AND SOURCES ANALYSIS OF MICROBIAL BIOMARKER GDGTS IN THE EAST CHINA SEA SEDIMENTS

The Glycerol Dialkyl Glycerol Tetraethers(GDGTs) is a group of newly discovered microbial biomarkers.The proxies based on GDGTs have become important indicators for revealing the sources of sedimentary organic matters and reconstruction of paleotemperature.In this study,we analyzed the content of the total organic matters and the fluxes of GDGTs in the core sediments from the DH5-1 station(29°28.118′N、123°06.639′E,water depth 63.5 m) located at the shelf area.The changes of organic matter sources were reconstructed using δ13C,C/N and BIT indexes during the past about 150 years.The results indicated that the enhanced East Asian winter monsoon in the past century strengthened the transport of terrestrial material from the Yangtze River Estuary to the shelf area.However,since the 1980s,increased human activities caused more nutrients influx which elevated marine production and reduced the relative percentage of terrestrial organic matters in the sediments.