长江口及邻近海域现代沉积物中正构烷烃分子组合特征及其对有机碳运移分布的指示

Compositional feature of n-alkanes in modern sediment from the Changjiang Estuary and adjacent area and its implication to transport and distribution of organic carbon

报道了长江口及邻近海域现代沉积物中正构烷烃的浓度及分布特征,通过因子分析法对正构烷烃来源进行了探讨.结果表明,调查站位正构烷烃主要可归纳为3种类型:陆源输入优势型(单峰群)、陆源和海洋内生混合类型(双峰群)和石油类污染类型(单峰型,不具奇偶优势).长江口邻近站位正构烷烃色谱指标的突变,是长江河口区2种不同水团造成沉积物差异的客观反映.除P4外,研究站位总正构烷烃含量(∑n Alk)与有机碳总量(TOC)相关性良好,且长江口东南-浙江沿岸软泥区正构烷烃的陆源高等植物组分(TER Alk)、海洋内生组分(PL1)、奇偶碳优势指数(CPI)等指标与运移距离呈线形关系.在因子分析显示不同来源的4种正购烷烃中,以陆源烷烃输入比重最大(51.5%),在陆源烷烃中又以东海河流物质贡献最大(49.1%);根据因子负荷差异,推测东海北部沉积有机质可能多数来源于苏北沿岸及老黄河口水下三角洲,冲绳海槽区则可能大部分来源于长江及东海内陆架物质,并探讨了其运移机理.

Concentration and composition feature of n-alkanes in modern sediments from the Changjiang Estuary and adjacent area are reported. Factor statistical analysis method is used to study the source of n-alkanes. The result shows that n-alkanes distribution patterns are characterized by three modes: the beside peak mode which indicates abundant of terrestrial plant origin, dual peaks mode indicating both terrestrial plant and marine biological input and petroleum contamination mode. The chromatogram proxies mutation of n-alkanes in border the stations of at Changjiang Estuary is the objective reflection of sediment diversity resulting from two types of different water masses. Relationship between ∑n-Alk and TOC retains a post correlation at all stations except P4, and TER-Alk, PL-1 and CPI are all highly correlated to the distance at the ZJ section. Factor statistical analysis reveals 4 types of input, among those the contribution of terrestrial plant input is the largest one (51.5%), and among the terrestrial plant inputs the contribution of the Changjiang River discharge is the largest one (49.1%). In terms of diversity of factor load, it is supposed that the sedimentary organic matter in the area of middle-northern East China Sea is mostly transported from North Jiangsu Province Coast and the old Huanghe River subaqueus delta, but a majority of sedimentary organic matter in Okinawa Trough maybe come from Changjiang River and the inner shelf of East China Sea, and then its migration mechanism is discussed.