秦淮河沉积物中重金属总量与形态分析

Total Contents and Species of Heavy Metals in Sediment of Qinhuai River

为了解南京内秦淮河沉积物中重金属直接和潜在的危害程度,为重金属污染防治提供科学依据,采用总量测定、分级提取法,分析、研究了内秦淮河沉积物重金属总量及形态特征。结果表明,沉积物中重金属元素的总量除铬外均已超出南京土壤背景值含量,其中Zn、As及个别断面的Cd含量属于重度污染;Hg、Pb、Cu属于中度污染,重金属污染程度的次序为Zn>As>Cd>Hg>Pb>Cu>Cr;由重金属形态分析可知,内秦淮河沉积物中最易对生物造成直接危害的重金属为Cd、Pb、Hg,具有潜在生态危害的重金属为Zn、Cu、As。由重金属总量与总磷的相关性探源分析说明Cu、Zn、Cd主要来源于生活污水的排放。

In order to find out the direct and potential harmful influence of heavy metals in sediment of inner Qinhuai river and supply scientific data to the protection against heavy metal pollution, this paper studied the total amount and morphological characteristics of heavy metals in the sediment of inner Qinhuai river by measuring the total amount and using selective sequentially extraction method. The total amount of each heavy metal element except chromium exceeded the background value of soil in Nanjing. It was found that Zn, As and individual sectional Cd belonged to the heavy-degree pollution, Hg, Pb, and Cu belonged to middle-degree pollution, and the severities of pollution were in an order of Zn〉As〉Cd〉Hg〉Pb〉Cu〉Cr. Analysis on the morphological characteristics of heavy metals showed that the content of exchangeable Cd was highest in the sediment of inner Qinhuai river, Pb was the second highest while As was the lowest, Cu and Zn existed mainly as organic matter bound and Fe-Mn oxides bound. In inner Qinhuai river, the heavy metals which were most likely to harm the biological environment directly were Cd, Pb and Hg, and the heavy metals which had potential harm were Zn, Cu and As. Source-searching analysis on the correlation of the total amount of heavy metal elements in the sediment to the total phosphorus content showed that Cu, Zn and Cd were mainly from domestic sewage.