中国东部海区bGDGTs的含量分布及其与环境因子的关系

【目的】近海是接受陆源输入的主要地带,沉积物中的有机质有可能记录了流域环境与气候变化的信息。本文以中国东部海区表层沉积物中陆源细菌来源的支链类甘油二烷基甘油四醚脂(branched Glycerol Dialkyl Glycerol Tetraethers,bGDGTs)为研究对象,分析其作为流域环境与气候变化指标的可行性。【方法】使用高效液相色谱-质谱联用仪(HPLC-MS)分析海域表层沉积物中bGDGTs的含量和分布,并进一步统计分析其与环境因子的关系。【结果】中国东部海区沉积物中bGDGTs的绝对含量呈现出区块状分布,在东海基本上随离岸距离的增加而降低,而在南黄海最高值出现在南黄海中心泥质区。支链和类异戊二烯指数(BIT)值除在长江口外上升流区外,基本呈现出随离岸距离的增加而降低的趋势。【结论】bGDGTs主要来源于陆源输入;有机质主要富存于细颗粒沉积物,且有海洋自生bGDGTs的贡献;相对于陆源输入,海洋自生bGDGTs以环状为主;除特殊环境,BIT仍可以作为衡量陆源输入相对多寡的指标;东部海区沉积物中的甲基化指数/环化指数(MBT/CBT)不能作为构建流域古气候变化的指标。

Distribution and Correlation with Environment Parameters of Branched Glycerol Dialkyl Glycerol Tetraethers in Surface Sediments from the East Coastal Sea of China

Objective] Most of the sediments in coastal region are terrigenous. The organic matter in coastal sediment can record the climate and environment change of the area. In this article, we analyzed and discussed the distribution and correlation with environment parameters of branched glycerol dialkyl glycerol tetraethers (bGDGTs) in surface sediment from the east coastal sea of China.Methods] The distribution of bGDGTs in the surface sediment was analyzed using a high performance liquid chromatogra-phy-mass spectrometry (HPLC-MS).Based on this, the correlation between the distribution of bGDGTs and the environment factor was analyzed.Results] We obtained that the concentration of bGDGTs in the east coastal sea of China (ECSC) shows different distribuyional style in different region. The bGDGTs concentration decreases with the increasing distance from coast in East China Sea (ECS), while it increases in the central muddy region of South Yellow Sea (SYS).The BIT value decreases with the increasing distance from shore except in the upwelling region off the Yangtze River Estuary.Conclusion] The bGDGTs mainly come from terrigenous soil. There is also some bGDGTs contribution from ocean. The organic matter mainly is enriched in the muddy sediment. The BIT can be used as an index to trace the relative abundance of terrigenous sources.The indexes of MBT and CBT cannot be applied as a paleotemperature in this region.