滇池内湖滨带重金属污染及其生态风险评价

水体沉积物是重金属元素的重要载体，其含量高低能反映水环境质量现状。采集滇池内湖滨带沉积物样品，分析了滇池内湖滨带表层沉积物中Pb、Cd、Cu、Zn、Cr、Ni、Fe、Mn 8种重金属元素含量特征，并用Hakanson潜在生态危害指数法评价其生态危害，旨在为合理预防和治理滇池内湖滨带的重金属污染以及内湖滨带生态系统的修复提供基础资料。结果表明，与“全国土壤环境质量标准”对比，表层沉积物中主要是Cd、Cu、Zn超标，重金属污染强度总体上是草海＞外海。不同重金属间的相关性分析结果表明，Cu-Cd之间呈极显著相关，说明这两种元素污染源可能相同，几种污染重金属与胶体矿物元素Fe、Mn间的相关性不大，说明在所调查沉积物中，Fe/Mn氧化物或氢氧化物共沉淀或吸附Pb、Cd、Cu、Zn、Cr、Ni元素量较少。由潜在生态风险评价结果可知，滇池内湖滨带表层沉积物已具极强生态危害，各重金属对滇池内湖滨带生态风险影响程度由高到低依次为：Cd〉Cu〉Pb〉Ni〉Zn≈Cr。

Heavy Metals Pollution and Potential Ecological Risk Assessment of Inner Lakeside Belt of Lake Dianchi

Heavy metals are mainly carried in sediment of water body, their contents play important role on the environmental quality of the water body. Aim of this study is to control heavy metal pollution in Lake Dianchi and provide the basic information of ecosystem recovery of inner lakeside belt. The content and characteristics of eight heavy metals （Pb, Cd, Cu, Zn, Cr, Ni, Fe and Mn） of surface sediments from the inner lakeside belt of Lake Dianchi were analyzed. Ecological risk index presented by Hakanson to assess the potential ecological risk of Lake Dianehi was utilized. The results showed that the inner lakeside belt of Lake Dianchi was polluted mainly by Cd, Cu and Zn compared with the ＂Environmental quality standard for soils＂, and the overall intensity of heavy metal pollution of Lake Caohai was stronger than that of Lake Waihai. According to the correlation analysis of various heavy metals, there was a remarkable correlation between Cu and Cd, which suggested their origin was the same. While the correlation between Fe, Mn and other heavy metals was weak, which indicated that Pb, Cd, Cu, Zn, Cr and Ni deposited or adsorbed by Fe/Mn oxides or hydroxides was less in the investigated water body. Based on the potential ecological risk assessment results, the surface sediment from the inner lakeside belt of Lake Dianchi had reached a high ecological risk level, and the order of ecological risk of heavy metals in inner lakeside belt of Lake Dianchi in the decline order was Cd〉Cu〉Pb〉Ni〉Zn ≈Cr.