长江口邻近海域表层沉积物中正构烷烃的分布特征和来源分析

通过对长江口邻近海域表层沉积物中正构烷烃（n-alkanes）的含量进行调查，结果表明:沉积物中烷烃的含量范围介于17.3×10-9~2132.3×10-9之间，平均值821.2×10-9。靠近长江口附近烷烃含量较低，除S5和S6站位，沿长江冲淡水自西向东方向，烷烃浓度自近岸至外海大致呈降低趋势。沉积物样品中烷烃的碳优势指数CPI_13-22和CPI_23-32分别介于0.43~0.72和1.13~2.81之间；除长江口近岸S5、S7站位，陆源有机质和海源有机质比值（TAR_HC）均显著小于1，低分子量烷烃与高分子量烷烃的比值（LMW/HMW）范围介于2.07~54.85之间，烷烃的生物标志物参数表明，沉积物中烷烃多为短链烷烃，且短链烷烃（C < 25）中的偶碳烷烃占优势，主要来源于海洋自生有机体的输入。

Distribution and sources of n-alkanes in surface sediments from Yangtze Estuary,China

The distribution of n-alkanes in surface sediments were studied in Yangtze Estuary, the concentrations of n-alkanes ranged from 17.3×10-9 to 2132.3×10-9, and the average concentration was 821.2×10-9.The minimum concentration of n-alkanes was detected near Yangtze Estuary, except for station S5 and S6, the n-alkanes concentration decreased gradually following the transport of Yangtze River diluted water.The range of CPI_13-22 ranged from 0.43 to 0.72, and CPI_23-32 varied from 1.13~2.81 in sediments, TAR_HC did not exceed 1except for station S5 and S7, while the ratio of LMW/HMW ranged from 2.07 to 54.85, the n-alkanes biomarkers revealed that the short-chain n-alkanes (C < 25) had significant even carbon preference, and were mainly derived from marine sources.