珠江口和邻近海域沉积有机质的来源及其沉积通量的时空变化

分析了珠江口和邻近海域沉积有机质(OM)的总有机碳(TOC)、总氮(TN)及稳定碳同位素组成〔δ(13C)〕等地球化学参数，并对有机质的来源和沉积通量进行了研究. 结果表明，珠江口沉积有机质来自大陆(52%)和水生(48%)混合来源；而邻近海域沉积有机质主要为水生来源(93%). 珠江口陆源有机质含量〔w(T－OC)为5.4 　mg/g〕远远高于邻近海域(0.49 　mg/g)，近年来珠江口TOC和陆源有机质(T-OC)的平均沉积通量分别为5.57和2.2～3.6 mg/(cm2·a)，说明珠江河口接受了大量的陆源有机物的输入，这是由于自20世纪后期的几十年以来，华南地区经济快速增长造成大量土地开垦，以及工农业生产和生活污水的排放所致. 珠江口和邻近海域的水生有机质沉积通量在近年均呈增加趋势，在珠江口达到最大值3.6 mg/(cm2·a)，说明大量的营养物质导致水体的富营养化，从而促使水域初级生产力的增长. 

Spatial and Temporal Variations of Sedimentary Organic Matter Origin and Accumulation Rate in the Pearl River Estuary and Adjacent Coastal Waters of South China Sea

The total organic carbon (TOC), nitrogen (TN) and stable carbon isotopic composition (δ(13C)) of organic matter (OM) were investigated, and the originand accumulation rate of OM in the Pearl River estuary and adjacent coastal waters were estimated using δ(13C) as a reliable indicator. The results showed thatin the estuary, OM was derived from mixed sources of terrestrial (52%) and marine (48%) origins, whereas OM in the coastal waters was mainly from marine sources (93%). The content of terrestrial OC (T-OC) in the estuary was 5.4 mg/g, which was much higher than that in the coastal waters (0.49 　mg/g). In recent years, the accumulation rate of TOC and T-OC in the estuary was estimated to be 5.57 and 2.2-3.6 mg/(cm2·a), respectively, suggesting that the Pearl River estuary received lots of terrestrial nutrient matter imported from the Pearl River during the last 30-40 years of the 20th century, due to increased urbanization andsewage effluent discharge. The accumulation rate of marine OC (A-OC) also increased in recent years in both the estuary and coastal waters, with a maximum of 3.6 mg/(cm2·a) in the estuary, suggesting that nutrient enrichment mighthave led to estuarine and coastal eutrophication. This would increase primary productivity in the water column.