东太平洋多金属结核勘探合同区表层沉积物脂肪酸分布及其物源指示意义

Distributions of surface sediment fatty acid and its source indication in polymetallic nodules contract area of the East Pacific Ocean

为丰富东太平洋多金属结核勘探合同区环境基线数据并解析底栖生物营养物质来源,本研究以气相色谱-质谱法,测定了中国大洋第45、50航次于东太平洋克拉里昂-克利珀顿区采集的表层沉积物中的脂肪酸组成,分析其分布特征及物源指示意义,探讨东太平洋多金属结核勘探合同区及周边区域表层沉积物生物群落结构的空间分布特征。结果表明,研究区域表层沉积物的脂肪酸组成主要包括以C11:0、C14:0 anteiso、C16:0为主的饱和脂肪酸、以C17:1ω7c为主的单不饱和脂肪酸、以C18:3ω6c(6,9,12)为主的多不饱和脂肪酸,其来源主要是细菌和真菌等生物。聚类分析及主成分分析结果表明,中国大洋矿产资源研究开发协会多金属结核勘探合同区KW1区块与中国五矿集团有限公司多金属结核勘探合同区A1、A2、A6、A8区块的脂肪酸组成类型较为相似,但后者各区块脂肪酸组成呈现出东西向的梯度差异。海底深度与颗粒有机碳通量的空间差异可能是造成脂肪酸组成具有地理差异的主要原因。此外,底层流和微地形等可能也会对沉积物脂肪酸空间分布产生影响。

In this study,the fatty acid compositions in the surface sediments collected from the Clarion-Clipperton Zone of the East Pacific Ocean during the 45 th and 50 th cruise were determined by gas chromatography-mass spectrometry(GC-MS).The source of sediment fatty acid and the distribution characteristics of microbial community structure were analyzed based on the variability of fatty acids in the Clarion-Clipperton Zone.Results showed that bacteria and fungi were the main sources of the sediment fatty acid in the studied area indicated by saturated fatty acids dominated by C11:0,C14:0 anteiso and C16:0,monounsaturated fatty acids by C17:1ω7c and polyunsaturated fatty acid by C18:3ω6c(6,9,12),respectively.The proportion of C16:0 was the highest among all stations,with a range of 9.27%-30.17%,followed by C14:0 anteiso,with a range of 4.43%-20.34%.Cluster analysis and principal component analysis showed that the fatty acid compositions in the contract areas of China Ocean Mineral Resources Research and Development Association(COMRA)and China Minmetals Corporation(CMC)were generally similar,but greater variability of fatty acid compositions were found in the CMC contract area.Water depth and particulate organic carbon fluxes may account for the geographic differences in fatty acids in the studied area,which may also be affected by the bottom flow and fine-scale topography on the seafloor.