北极现代沉积物中正构烷烃的分子组合特征及其与不同纬度的海域对比

北极海域楚科奇海和白令海表层沉积物的正构烷烃气相色谱图呈双峰群分布,楚科奇海正构烷烃分子组合特征高碳数峰群MH(主峰碳)在nC25-nC33、低碳数峰群MH在nC16-nC20范围;白令海高碳数峰群MH在nC25-nC27、低碳数峰群MH在nC17-nC22范围。两海域的OEP(奇偶优势指数)各为0.9-3.81、0.409-3.26;C-23/C+24比值为0.18-1.53、0.40-2.57之间;TABHC(陆/水生类脂物)比值在0.57-11.35、0.32-5.97之间。根据分子组合特征表明楚科奇海的陆源物质输入要比白令海大,而白令海的表层生产力又比楚科奇海高。本文将北极海域现代沉积过程中的正构烷烃分子组合特征与南极进行对比,同时又将高纬度海域与低纬度海域渤海、黄海、东海和南海进行对比,研究发现由高纬度北极到低纬度海域的陆源输入特征依次减弱,而海洋生物自身起源特征加强。不同纬度海域的表层沉积物中正构烷烃呈现出不同的分子组合差异,受到现代海洋沉积过程中物质来源、环境、气候诸多因素的影响。

THE COMPOSITION CHARACTERISTICS OF N-ALKANES IN THE MODERN SEDIMENTS OF THE ARCTIC AND THE COMPARISON WITH THAT OF SEA AREAS OF DIFFERENT LATITUDES

Gas chromatography of n-alkanes in the surface sediments appears as double peaks in the Chukchi and the Bering Sea. The high carbon peak is at MH nC_~25 —nC_~33 and the low carbon peak locates at MH nC_~16 —nC_~20 in the Chukchi Sea. The high carbon peak is at MH nC_~25 —nC_~27 and the low carbon peak locates at nC_~17 —nC_~22 in the Bering Sea. OEP are 0.9—3.81 and 0.409—3.26, the ratio of C-_~23 /C+_~24 are between 0.18—1.53 and 0.40—2.57; the ratio of TAB_~HC are 0.57—11.35 and 0.32—5.97 respectively. The results suggest that the substance input from terrigenous origin in the Chukchi Sea is larger than that in the Bering Sea. But the productivity in the surface water in the Bering Sea is higher than that in the Chukchi Sea. The composition characteristics of n-alkanes in the modern sediments of the Arctic is compared with that in the Antarctic as well as with that in the Bohai Sea, the Yellow Sea, The East China Sea and the South China Sea. The results indicate that the characteristics of terrigenous origin become weaker while marine biological inputs appear stronger from high to low latitudes. The discrepancy of composition characteristics of n-alkanes in different sea areas have been contributed by the process of sedimentation that influenced by environments and climates.