南京市绿地土壤重金属分布特征及其污染评价

为了解南京市主城区绿地土壤中重金属污染现状，分析了南京市主城区绿地表层土壤5种重金属元素（Cr、Cu、Zn、Pb和Cd）的含量状况及其空间分布特征，并利用单因子污染指数法、内梅罗综合指数法及潜在生态风险指数法对重金属的污染程度及其潜在生态风险进行了评价.结果表明，南京市主城区绿地土壤中5种重金属元素的平均含量均高于南京市土壤背景值，单因子污染等级依次为Cd > Pb > Cr > Cu >Zn，平均内梅罗综合指数为2.72，土壤呈中度污染水平.土壤重金属元素（Cr、Cu、Zn和Pb）的单项生态风险指数都小于10，具有轻微风险，而Cd的生态风险指数达到了97.32，具有强风险；综合潜在生态风险指数<150，总体属于低生态风险.5种重金属元素在空间上呈斑块状分布，Cr、Cu、Zn和Pb含量高值区域集中在城区东北部的绿地，Cd含量高值区集中在西南部及西北部绿地.通过本研究可知，南京市主城区绿地土壤中Cd的污染较为严重，在城市生活中需引起重视.

Distribution Characteristics and Pollution Evaluation of Heavy Metals in Greenbelt Soils of Nanjing City

Concentrations and the spatial distribution of heavy metals (Cr, Cu, Zn, Pb, and Cd) in greenbelt soils in the main areas of Nanjing City, Jiangsu Province, were investigated and pollution levels were assessed using the single factor pollution index (SFPI), Nemerow integrated pollution index (NIPI), and potential ecological risk coefficient (PERC). The results showed that the average concentrations of heavy metals in greenbelt soils exceeded their background values, with the SFPI results ranked Cd > Pb > Cr > Cu > Zn, and the mean NIPI was 2.72 indicating that the greenbelt soils are moderately polluted. The PERC of each heavy metal (Cr, Cu, Zn, and Pb) was less than 10, indicating that the greenbelt soils present a slight ecological risk, while the PERC of Cd reached 97.32, indicating a strong ecological risk. The composite PERC of all heavy metals was less than 150, indicating a slight ecological risk overall. The five heavy metals showed a patchy spatial distribution, with high concentrations of Cr, Cu, Zn, and Pb in the greenbelt soils of northeast areas, and high concentrations of Cd in the southwest and northwest. Based on the results of study, Cd pollution in greenbelt soils in main areas of Nanjing City is relatively serious, which requires further attention.