北方某水库表层沉积物重金属的赋存形态及其环境影响因子分析

摘要

为了解北方某水库重金属污染状况,采用BCR连续提取法对该水库表层沉积物中Cu、Pb、Zn、Cd的赋存形态进行了分析,对其含量及空间分布进行了研究,结合重金属总量讨论了各元素的潜在环境风险.结果表明,该水库表层沉积物中Cu、Pb、Zn、Cd的平均质量比分别为65.20 mg/kg、36.69 mg/kg、137.5 mg/kg、2.38 mg/kg,与该地区土壤元素背景值、该地区水系沉积物平均值及全国水系沉积物平均值相比,4种重金属元素均有一定程度的累积,其中Cd累积最为严重.形态分析结果表明,Cd主要以醋酸可提取态及可还原态存在,具有很高的环境风险;Pb主要以极高比例的可还原态存在,潜在风险较高;Zn和Cu存在较大比例的酸可提取态及可还原态,也具有一定程度的潜在风险.各元素生物有效性即可提取态含量排序为:Cd＞ Cu＞ Pb＞ Zn.%For heavy metal pollution situation of a reservoir in the north part of China,Cu,Pb ,Zn and Cd concentrations in surface sediments were analyzed in sediments by using BCR three stage sequential extraction procedure.The potential environmental risks were discussed according to total contents of the heavy metals.The results indicated that the average concentrations of Cu,Pb,Zn and Cd were 65.20 mg/kg,36.69 mg/kg,137.49 mg/kg and 2.38 mg/kg respectively.Compared with regional background value,river average concentrations of regional and nationwide sediments,the enrichment of the 4 elements was enhanced,especially Cd.Cd mainly existed in weak acid soluble fraction and reducible fraction with very high environmental risk,Pb mainly existed in reducible fraction with high environmental risk,Zn and Cu presented risk to some extent,with larger shares of weak acid soluble fraction and reducible fraction,and the bioavailability for four metals varied of the descending order of Cd > Cu > Pb > Zn.