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2011年对珠江口外内陆架海域22个点位表层沉积物中主要的重金属Cr、Ni、Cu、Pb、Zn、Cd和As含量、形态特征、来源控制因素以及潜在生态风险进行了研究。采用了BCR提取法分析各种重金属赋存形态,并依据各种重金属的形态特征与沉积物基质属性进行了相关因子分析,了解其分布的控制因素。结果表明:珠江口外内陆架沉积物重金属分布特征为由陆向海的方向,随着水深增大而逐渐降低。重金属赋存形态中Cr、Ni、Cu、As主要以残渣态存在,Pb主要以可还原态存在,Cd主要以酸提取态存在,Zn主要存在于残渣态与可还原态。各重金属非残渣态比重Cd最高,Cr最低,表明Cd的迁移性最强。各元素非残渣态在平面上的分布与总量分布模式相关性较好,因此,珠江口外内陆架海域通过总量来确定区域重金属污染情况在一定程度上是可靠的。重金属元素与黏土含量、可还原态Fe、Mn含量普遍具有较好的相关性。珠江口外内陆架的重金属来源比较复杂,主要来源于附近大陆的物质输入。运用酸提取态百分含量风险评估法对重金属潜在生态风险进行评价,发现研究区各元素综合风险评价除Cd为高风险外,Cr元素综合风险评价为无风险;其余为中一低风险等级。
In 2011, the content of heavy metals such as Cr, Ni, Cu, Pb, Zn, Cd and As, morphological characteristics, source control factors and potential ecological risks in surface sediment of 22 sites in the Pearl River Estuary and outer continental shelf were studied. BCR extraction method was used to analyze the occurrence patterns of various heavy metals, and related factors were analyzed according to the morphological characteristics of various heavy metals and sediment matrix properties to understand the control factors of their distribution. The results show that the distribution of heavy metals in the sediments from the Pearl River Estuary is from the direction of seaward to the sea, and decreases with the increase of water depth. Cr, Ni, Cu, As are mainly in the residual state in heavy metal speciation, while Pb is mainly in reducible state, while Cd is mainly in acid extractable state, while Zn mainly exists in residual state and reducible state. Each heavy metal non-residue state the highest proportion of Cd, Cr the lowest, indicating that the strongest mobility of Cd. The non-residual state of each element in the plane has a good correlation with the total amount distribution pattern. Therefore, determining the regional heavy metal pollution by the total amount in the Pearl River Estuary Outer-shelf area is to some extent reliable. Heavy metal elements and clay content, reducible Fe, Mn content generally has a good correlation. The source of heavy metals in the Pearl River Estuary Outer Continental Shelf is rather complicated, mainly due to the input of materials from the nearby mainland. The potential ecological risk of heavy metals was evaluated by using the method of percentage assessment of acid extraction. It was found that the comprehensive risk assessment of elements in the study area was risk-free except for Cd, and the rest was the middle-lower risk level.