Heavy Metals Contents and Risk Assessment of Farmland on the Edge of Sichuan Basin

This study features a survey of the concentrations of heavy metals (Cu, Cd, Cr, Ni, Pb, Mn, Co, Se) in surface soils (0-30 cm), carried out in edge of Sichuan Basin (Pingdi, Puan, Xingwen, Gulin). The contamination of heavy metals in soil was assessed with single-factor pollution index method and Nemerow comprehensive pollution index method. The results showed that Cu, Cr, Ni, Pb, Co were main risk factors of soil heavy metal pollution. In Gulin, the concentrations of Cd, Mn and Se were higher than other three areas, with the sample over-standard rate of 90, 20 and 30%. The Nemerow assessment showed that the comprehensive pollution index of Gulin was above 1, while Pingdi, Xingwen, Puan was below 1. It indicated that the soil in Gulin was slight polluted, and the soil in Pingdi, Xingwen, Puan were clean.