珠江长州断面底泥重金属污染潜在生态危害评价

Assessment of potential ecological risk from heavy metals in sediment in the Changzhou section of the Pearl River

测定了珠江广州河段长州断面底泥中重金属镉、铬、铜、铅的质量比,采用Tessier形态分类法对它们在底泥中的存在形态进行了提取和测定。监测分析表明,该断面底泥中镉、铬、铜、铅质量浓度均高于全国湖泊底泥中的平均值。该断面底泥中镉、铬、铜、铅质量比分别为广东土壤背景值的49.50倍、3.62倍、14.24倍、5.51倍,底泥成为这些重金属的富集地。镉以可交换态为主,占总量的比例为47.47%;铬和铅以残渣态为主,占总量的比例分别为42.35%和47.28%;铜主要以有机态及硫化物结合态为主,占49.06%;残渣态较低,占18.26%。采用潜在生态危害指数法对该断面底泥中的镉、铬、铜、铅进行了潜在生态危害评价,结果表明:镉潜在生态危害强,铬、铜、铅的潜在生态危害轻微。

the mass ratios of heavy metals such as Cd, Cr, Cu and Pb in sediment in the Changzhou section of the Guangzhou segment of the Pearl River were measured, and the existing forms of heavy metals were determined by Tessier sequential chemical extraction procedures. The results show that the contents of heavy metals such as Cd, Cr, Cu and Pb in sediment in the Changzhou section are higher than the average values in lake deposits throughout the country. The contents of Cd, Cr, Cu and Pb in sediment are 49.50 times, 3.62 times, 14.24 times and 5.51 times higher than the background value of soil in Guangdong Province, respectively. The bed deposit becomes the place for enrichment of heavy metals. Cd exists mainly in the exchangeable form, which is about 47.47% of the total amount. Cr and Pb exist mainly in residual form, which is about 42.35% and 47.28% of the total amount, respectively. Cu exists mainly in organic and sulphide form, which is about 49.06% of the total amount and 18.26% in the residual form. The ecological risks of these four heavy metals were assessed with Hakanson＇ s potential ecological harmfulness index. The results indicate that the ecological harmfulness of Cd is high, and that of Cr, Cu and Pb are lower.