北京顺义区土壤重金属污染生态风险评估研究

在北京顺义区农业用地采集了412份土壤表层样品,采用地积累指数法和潜在生态危害指数法对区域土壤重金属污染生态风险进行评估。结果表明:研究区土壤6种重金属元素(Cu、Zn、Pb、Cd、As和Hg)的地积累指数(Igeo)平均值均小于0,处于无污染程度;但处于Hg、Zn和Cd"轻度-中等污染"和"中等污染"的土壤样本分别有12.6%、12.9%和17.0%。土壤重金属生态风险指数(RI)平均值为93.07,属于轻度生态危害;轻度、中等和强度生态危害的比例分别为95.6%、3.9%和0.5%;均有超过20%的土壤样本处于Hg和Cd中等生态危害以上的水平;从不同土地利用类型中土壤样本的RI分析,菜地土壤RI平均值为109.55,达到中等污染等级的比例为14.3%。从研究区土壤重金属生态危害指数的空间分布特征分析,区域内潮白河、小中河和金鸡河对区域生态存在影响。

Ecological Risk Assessment of Heavy Metals in Soils in Shunyi, Beijing

Soil heavy metals possess latent and long-term risks to human health. Here we collected 412 surface soil samples from agricultural soils of Shunyi district of Beijing and used the index of geo-accumulation(I_geo) and potential ecological risk index(RI) to evaluate the ecological risks of heavy metal pollution in soils. The results revealed that the average I_geo values of heavy metal Cu, Zn, Pb, Cd, As and Hg were less than 0, belonging non-pollution. However, there were 10% of soil samples in which I_geo of Cu, Cd and Hg were at low or moderate pollution levels. The average RI value of all soil samples was 93.07 in studied area, having mild ecological hazards. About 95.6%, 3.9% and 0.5% of soil samples were in mild, moderate and high ecological hazards, respectively. For Hg and Cd, more than 20% of soil samples were in moderate ecological hazards. The mean value of RI was 109.55 in vegetable soils and 14.3% of soil samples were at medium pollution level. Spatial distribution of ecological risk indices of heavy metals in soils of studied area indicated that Chaobai, Xiaozhong and Jinji rivers had the ecological risk.