神狐海域Site4B表层沉积物中脂肪酸组成及其碳同位素分布特征

通过对神狐海域表层5个沉积物样品进行脂肪酸组成及其碳同位素分布特征测试和研究，结果表明总脂肪酸含量分布为5.14~8.99 μg/g，碳数分布范围从C₁₂到C₃₂，类型包括正构饱和脂肪酸、支链脂肪酸、单不饱和脂肪酸、多不饱和脂肪酸和类异戊二烯酸等计48种；样品中饱和的短链脂肪酸主要来自细菌与浮游生物，而长链饱和脂肪酸来自陆源高等植物，其比例表明研究海域中海洋细菌与浮游生物输入量远远大于陆源高等植物的输入。支链脂肪酸10me16:0与单不饱和脂肪酸18:1ω9、16:1ω9主要来自硫酸盐还原菌，而单不饱和脂肪酸16:1ω7很大可能来源于硫氧化菌，比较相对含量得出神狐海域表层沉积物为还原环境。样品中检测出8种类异戊二烯酸，主要是植烷酸和17，21-ββ二升藿烷酸，及少量的姥鲛酸，推测为叶绿素a和细菌微生物的共同贡献。

Molecular distributions and carbon isotopic compositions of fatty acids in the surface sediments from Shenhu Area,northern South China Sea

The lipid biomarkers of fatty acids in the surface sediments from Shenhu Area,northern South China Sea continental slope were investigated in the present paper. The total contents of the fatty acid from the sediments amounts to 5.14 ~ 8.99 μg/g,and its carbon number ranges from C₁₂ to C₃₂. The fatty acid includes 48 types such as the saturated fatty acid,branched fatty acid,monounsaturated fatty acid,polyunsaturated fatty acid and isoprenoid acid. In these five samples,the short chain saturated fatty acid mainly came from bacteria and planktons,while the long chain saturated fatty acid was from the terrigenous higher plants. Their ratio indicates that the input of marine bacteria and planktons is far more than that of the terrigenous higher plant in the studied area. The branched fatty acid 10me16:0 and monounsaturated fatty acid 18:1ω9、16:1ω9 are mainly synthesized by the sulfate reducing bacteria,while 16:1ω7 is from the sulfur oxidizing bacteria. Comparison of the relative content of them,the author believes that the surface sediments of the Shenhu area may be embraced by reducing environment. In addition,eight isoprenoid acids detected in the samples,mainly phytanic acid and 17β(H),21β(H)-32-hopanoic acid,and a small amount of the pristane acid,presumably for the joint contribution of chlorophyll A and bacterial microorganisms.