巢湖东区底泥污染物分布特征及评价

测定了巢湖东区底泥样品中有机质、总氮、总磷、铅、铜、铬和锌的含量,其中,表层w(有机质),w(总氮)和w(总磷)的平均值分别为2 016%,0 108%和0 053%;w(Pb),w(Cu),w(Cr)和w(Zn)的平均值分别为40 2,40 1,79 2和123 8mg kg。研究了底泥污染物的垂直分布特征,其一般规律是严重污染层高于污染过渡层,污染过渡层高于正常湖泥层。用潜在生态危害系数法对底泥重金属污染作了评价,结果表明,巢湖东区底泥重金属含量高于安徽土壤背景值,但仍属于低生态危害。对有机质与其他污染物之间的关系作了相关分析,其中w(总氮)(y,%)与w(有机质)(x,%)之间的线性方程为:y=0 1194+0 0475x,相关系数0 975,线性高度显著,说明总氮与有机质具有同源性。底泥中的w(C) w(N)为18.62,w(N) w(P)为2 12,与其他富营养化湖泊比较,没有显著差异。有机指数均高于底泥肥污染标准。 

Characteristics of Distribution of Pollutants and Evaluation in Sediment in the East Area of Chaohu Lake

Organic content, total nitrogen, total phosphorus, lead, copper, chromium and zinc in the sediments of Chaohu Lake are determined. At the sediment surface layer,mean concentration of pollutants are 2.016%, 0.108%, 0.053%, 40.2 mg/kg, 40.1 mg/kg, 79.2 mg/kg and 123.8mg/kg, respectively. The vertical distributions of pollutants in sediment are investigated. The distributions rule is A layer (serious polluted layer)>B layer (transition layer)>C layer (normal lake mud layer). The potential ecologic risk factor is used to evaluate metal pollution in sediment of Chaohu Lake. The results show that although concentrations of metals are high than those of soil background at Anhui Province, potential ecological risk is low for the metal contamination in the lake sediments. The correlative characteristics between organic content and other pollutants are analyzed. The linear equation between total nitrogen and organic content is y=0.1194+0.0475x with 0.975 of correlation coefficient. The highly significant correlation indicates that total nitrogen and organic content have same sources. The C/N ratio and N/P ratio in the lake sediments are 18.62 and 2.12, respectively, showing no significant difference compared with other lakes with eutrophication. Organic index is higher than standard level of fertility of sediment.