东海陆架泥质区沉积有机质的物源分析

Source of sedimentary organic matter in the mud areas of the East China Sea shelf

色谱和色谱/质谱分析表明,济州岛西南泥质区正构烷烃、姥鲛烷、植烷、藿烷和甾烷等生物标志物的特征与现代长江口、老黄河口和新黄河口的河流沉积物均区别很大,该泥质区的沉积有机质主要来源于海洋低等生物(如细菌和藻类等)以及陆源高等植物的输入,表现为不同来源和成熟度的生物标志物的混合,同时该泥质区沉积有机质与矿物碎屑沉积物来源不尽相同。长江口泥质区正构烷烃高相对分子质量部分与长江口沉积物相似,正构烷烃和藿烷所反映的有机质成熟度高于现代长江和老黄河口沉积物,甾烷的成熟度与长江相仿而明显高于老黄河口沉积物。长江口泥质区的沉积有机质主要来源于长江输入的陆源高等植物碎片和海洋源的低等生物。东海陆架近岸与远端泥质区沉积有机质的物源很不相同。

The biomarkers including n alkanes, pristane, phytane, hopanes and steranes of the sedimentary organic matter in surface sediments taken from themud areas on the East China Sea (ECS) shelf, and in riverine sediments from theestuaries of Changjiang, modern Huanghe and old Huanghe, respectively, were analyzed with GC and GC/MS. The sources of sedimentary organic matter in the mud areas on the ECS shelf were studied based on the biomarker analysis. The results show that the characteristics of the composition of n alkane, pristane, phytane, hopanes and steranes of the distal mud area in the southwest Cheju Island are very different from those of Changjiang, modern Huanghe and old Huanghe sediments. The sedimentary organic matter of the distal mud area is mainly from marine lower aquatic organism, such as algae and bacteria, and terrigenous higher plant debris. The amount of terrigenous higher plant debris is much less than that of marine organism source in this mud area. As the result of the multi sources ofthe sedimentary organic matter, the biomarkers presenting different source and maturity of the organic matter are mixing together in this mud area. It is suggested that the source of sedimentary organic matter of this mud area be quite different from that of mineral debris sediments which are mainly from the resuspended sediments in the old Huanghe aqueous delta in the northern Jiangsu Province. The composition of the part of high molecular weight n alkanes of the nearshore mud area in the Changjiang estuary is as like as that of the Changjiang sediments, and somewhat different from that of the old Huanghe sediments. The maturities of n alkanes and hopanes of this mud area are higher than those of the modern Changjiang and old Huanghe sediments. The maturity of steranes in this mud area is as like as that of the Changjiang sediments, but much higher than that of the old Huanghe sediments. It is indicated that the sedimentary organic matter of the nearshore mud area in the Changjiang estuary is chiefly from the marine lower aquatic organism and terrigenous higher plants which are mainly from the Changjiang discharge to the sea. The relative amount of the higher plant source in the sedimentary organic matter of the mud area in the Changjiang estuary is muchmore than that of the mud area in the southwest Cheju Island, and vise versa for the low aquatic organism source. All results supported that the sources of sedimentary organic matter in the nearshore mud area and distal mud area on the ECSshelf are quite different.