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(Igeo)and potential ecological risk index(RI)to evaluate the ecological risks of heavy metal pollution in soils. The results revealed that the average Igeovalues 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 Igeoof 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% and0.5% 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.