杭州临安社区花园土壤重金属污染特征及风险评估

Characteristics and Risk Assessment of Soil Heavy Metal Pollution at Community Gardens in Lin’an District of Hangzhou

为了解杭州临安区社区花园土壤重金属污染情况,对临安锦城街道的社区花园进行土壤采样,利用IDW空间插值、主成分和相关性分析、单因子指数法、内梅罗综合指数法、潜在生态风险分析及健康风险暴露指数法等方法,分析社区花园土壤重金属空间分布、污染源及土壤重金属污染特征。结果表明:Cu、Zn、Cd、Ni、As已超过杭州市背景值,以As和Zn较为显著,整体上东部污染重于西部;社区花园的重金属主要来源于交通、农业或生活污染;37%的地区呈现重度或中度污染,3.23%的地区存在中等潜在生态风险,以Cd和As较为严重;As、Cr和Ni对人体的非致癌风险超出阈值,致癌风险中Cr和As超出安全值。因此,应在重金属污染指数法的基础上对社区花园进行潜在生态风险分析和健康风险评估,重点治理对人体健康影响较大的重金属元素和污染区域。

In order to understand the soil heavy metal pollution at the community gardens in Lin’an District of Hangzhou,soil samples are collected at the community garden of Jincheng Street,and the spatial interpolation method of inverse distance weighted(IDW),principal component and correlation analysis,single-factor index method,Nemerow composite index method,potential ecological risk analysis,and health risk exposure index method are adopted to analyze the spatial distribution of soil heavy metals,pollution source and the characteristics of soil heavy metal pollution.The results show that Cu,Zn,Cd,Ni and As has exceeded the background value of Hangzhou,among which As and Zn have more significantly higher value,and pollution in the east part of the garden is heavier than that in the west.The heavy metals in the community garden mainly come from transportation,agricultural or domestic pollution.Heavy or moderate polluted areas in the garden account for 37%of the total areas,while 3.23%of the area presents moderate potential ecological risk,with higher volume of Cd and As.The non-carcinogenic risks of As,Cr and Ni are beyond the threshold,while the risks of Cr and As exceed the safety.It is concluded that for community gardens,the potential ecological risk should be analyzed on the basis of heavy metal pollution index method,and the heavy metal elements and polluted areas with greater impact on human health should be treated in combination with health risk assessment.