珠江口及近海沉积有机质来源判断

Distinguish of sources of organic matter in sediment in Pearl Estuary and adjacent water

用二元混合模型对有机地球化学指标之间的关系进行模拟,结果表明珠江口和近海沉积物样品OC/N与δ15N在早期成岩过程中均发生了较大改变,OC/N可用作判断有机质来源的辅助证据,而δ15N不宜用作沉积有机质来源的指示。δ13Corg则可以较可靠地用来评价来源的贡献。稳定C同位素二元混合模拟结果表明从珠江河流出海口往近海方向,陆源有机质所占比例呈下降趋势,在珠江口内,陆源有机C的比例略大于水生有机C,而近海有机质以当地水生藻类为主要来源。

The correlations of organic geochemistry proxies were simulated using two end-member mixing model. OC/N ratio and δ15N both altered significantly due to diagenesis, so OC/N ratio can help discriminate the sources of organic matter in sediment δ15 N can not be used to indicate the origins of the organic matter, and δ13 Corg can be a reliable proxy to the sources of organic matter. Calculations using two end-member mixing model of organic matter showed that the proportion of terrestrial organic matter isdecreased with the distance from Pearl River outlets. Generally, the terrestrial organic matter accounted for more than half of that in the sediment cores sampled in the Lingding bay, while the organic matter in the adjacent shelf was predominantly algal-derived.