江苏苏北湿地土壤重金属污染特征及评价

Pollution characteristics and assessment of heavy metals in wetland soil in the area of northern Jiangsu Province

本文研究了苏北盐城湿地土壤重金属Pb、Cu、Cr、Cd、Zn污染状况,并采用相关性分析和主成分分析对土壤重金属的来源进行了分析,同时,通过内梅罗综合污染指数法、地质累积指数法和Hakanson潜在生态风险指数法对土壤重金属的污染情况进行了评价.结果表明,研究区的土壤中Pb、Cu、Cr、Cd和Zn的平均含量分别为26.28、27.55、57.71、1.04、70.05 mg·kg-1,除了Cd有97.1%超过土壤环境质量二级标准,其余均未超过二级标准.除Pb含量分布变化幅度较小外,其余4种重金属含量分布变化幅度都较大.相关性分析和主成分分析表明研究区域的Pb、Cu、Cr、Zn存在相关性,它们可能来自于相似来源,主要来源于工业排放;Cd与其它重金属无相关性,表明来源不同,可能主要来自于农业化肥的施用.内梅罗综合污染评价法及地质累积指数法结果表明,各重金属污染程度从大到小的顺序为:Cd>Cu>Zn>Pb>Cr.土壤样品的内梅罗综合污染指数P综合=6.11,说明总体上该区域土壤已达到重度污染等级.研究区域的综合潜在生态风险指数RI为261.71,总体处于中度生态风险等级,并且Cd是主要贡献因子.

The concentrations and potential ecological risk of heavy metals in wetland soil of Northern Jiangsu Province were investigated. The possible sources of heavy metals in soil were analyzed by correlation analysis and principal component analysis. Meanwhile,the pollution level of heavy metals in soil was evaluated by Nemerow comprehensive pollution index,geoaccumulation index, and hakanson potential ecological risk index. The results showed that the average concentrations of Pb,Cu,Cr,Cd,and Zn were 26.28,27.55,57.71,1.04,and 70.05 mg·kg^-1,respectively. The concentrations of Pb,Cu,Cr,and Zn were below the secondary standard of soil environmental quality,except for Cd. Cd concentrations 97. 1% of samples exceeded the secondarystandard of soil environmental quality. The coefficient of variation（CV） indicated moderate variability for Cu,Cr,Zn and Cd,and small variability for Pb. The correlation analysis and principal component analysis demonstrated that there were linear correlation between Pb,Cu,Cr,and Zn,which indicated that they were from the same source,such as industrial source. There was no relationship between Cd and other heavy metals,which indicated that Cd was from other sources such as agricultural fertilizers. The nemerow comprehensive pollution index and geoaccumulation index analysis showed that the pollution degree of heavy metals was in the order of Cd〉Cu〉Zn〉Pb〉Cr. The nemerow comprehensive pollution index was 6.11,which indicated that the wetland soil was under the severe pollution level. The potential ecological risk index（RI） was 261. 71,which that heavy metals caused moderate potential ecological risk,and Cd was the main pollution factor.