Distribution and Environment Significance of Redox Sensitive Trace Elements of the Changjiang Estuary Hypoxia Zone and Its Contiguous Sea Area
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摘要: 对长江口及其邻近海域表层沉积物和底层悬浮体中氧化还原敏感元素分布规律和富集特征进行了分析与研究。结果表明氧化还原敏感元素在研究区具有明显的“离岸富集”特征，去除粒度效应、陆源碎屑来源组分和有机质的吸附作用等因素的影响之后，氧化还原敏感元素仍显示出在缺氧区的富集。通过同一站位底层悬浮体和沉积物中氧化还原敏感元素含量的分析比较，发现底层水缺氧是导致氧化还原敏感元素Mo、Cd、V等在沉积物中富集的主要原因。Mo、Cd、V等元素的不同富集程度可用来反映缺氧区的缺氧程度。因此，Mo, Cd, V等RSE在长江口外缺氧区及其邻近海域具有氧化还原环境指示意义，可以指示长江口外缺氧区的存在与大体范围，并可在一定程度上用来衡量缺氧区的缺氧程度。U理论上虽然也对环境的氧化还原条件敏感，但由于受陆源碎屑来源组分的影响较大，在长江口外缺氧区的富集并不明显，因此U在研究区不具有氧化还原环境指示意义。Abstract: This study discusses the distribution and enrichment characteristic of redox sensitive elements defined both the seabottom surface sediments and in suspensions off the Changjiang Estuary hypoxia zone and its contiguous sea area. The distribution of RSE “enrich off the sea shore”. The results, after getting rid of the influence of “grain size effects”, terrigenous components and adsorption by organic matter, revealed that distribution of RSE still “enrich off the sea shore”. By comparison the RSE concentration between bottom layer suspension and surface sediments, the paper believes that the hypoxia zone of the bottom water induces the RSE to enrich in sediments. The authigenic precipitation mechanism and the potential energy of Mo, Cd and V is different, their different enrichment characteristics can be used as redox indicators of the hypoxia zone. So, redox sensitive elements such as Mo, Cd and V have the redox environmental significance of the Changjiang Estuary and its contiguous sea area. U are also sensitive to redox conditions of bottom sediments theoretically, the terrigenous components of U conceal the enrichment of U in hypoxia zone, and so U have no environment significance in the hypoxia zone of the research area.
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