太湖表层沉积物重金属污染评价与来源分析

Pollution Evaluation and Source Apportionment of Heavy Metals in Surface Sediments of the Taihu Lake

对太湖湖区表层沉积物中11种重金属的总量进行调查分析,借助地累积指数法和潜在生态风险指数法分析了重金属的污染程度和生态风险,并利用主成分分析-绝对主成分分数-多元线性回归受体模型对重金属来源进行解析。结果显示太湖沉积物中Cd、Sb含量平均值分别为江苏省土壤背景值的4.29倍和3.18倍,地累积指数表明Cd和Sb为偏中度-中度污染,其他重金属为轻度污染;潜在生态风险指数表明Cd和Sb具有较重生态风险,其他重金属生态风险低。空间分布上,北部竺山湾和梅梁湾的重金属污染情况最严重,其表层沉积物中Co、Cr、Cu、Mn、Ni、Pb、Sb、Zn显著富集,其中Co、Cr、Cu、Mn、Ni、Sb、Zn主要受入湖河流及湖泊沿岸工业因素影响,Cu、Mn、Zn还受入湖河流及湖泊沿岸农业活动影响,另外,Cu、Pb受河流及湖泊沿岸城市交通因素影响;西太湖沉积物中富集Cd,主要受入湖河流沿岸农业活动影响;南太湖Ba、Mo、Pb的富集主要为交通因素的影响;东太湖具有最低的重金属暴露水平。2000年以来太湖湖区的清淤工程使Pb、Cu、Cd含量分别降至清淤前的38.72%、24.93%、27.47%,但清淤治理效果具有时效性,未来太湖重金属的防治需要兼顾源头控制和多种治理措施并举。

To understand the heavy metal pollution in surface sediment of the Taihu Lake,samples were collected and 11 heavy metals were determined.Geo-accumulation Index(Igeo)and the potential ecological risk index(RI)were used to assess the heavy metal pollution,and PCA-APCS-MLR were employed to identify the sources of heavy metals.The results showed that the average contents of Cd and Sb were 4.29 times and 3.18 times higher than those of soil background values in Jiangsu Province.Igeoand RI both showed that Cd and Sb were the main pollutants in surface sediments of the Taihu Lake.The sources of heavy metals are mainly human activities such as industry,agriculture,and transportation which enter the lake from inflow rivers.The heavy metal pollution in Zhushan Bay and Meiliang Bay were the most serious.Co,Cr,Cu,Mn,Ni,Pb,Sb,and Zn were significantly enriched,of which Co,Cr,Cu,Mn,Ni,Sb,Zn were affected by industrial sources;Cu,Mn,Zn were affected by agricultural activities;Cu and Pb were affected by urban traffics;Cd enrichment in west Taihu Lake was mainly affected by agricultural activities;Ba,Mo,Pb in south Taihu Lake were enriched and affected by traffics;East Taihu Lake was relatively clean.Comparative data from previous studies indicated that heavy metals in the sediment of the Taihu Lake decreased greatly after desilting since 2000,for example,concentrations of Pb,Cu,Cd reduced to 38.72%,24.93%and 27.47%of that before desilting,respectively.However,considering the time-effectiveness of desilting,the future control of heavy metal in the Taihu Lake should involve more treatment scheme and protocols.