Accumulation and pollution risk of heavy metals in long-term vegetable-planted soils

To evaluate the accumulation and pollution risk of heavy metals in the long-term vegetable-planted soils in the suburb of Changsha city, 57 soil samples in the long-term vegetable-planted fields were collected and the contents of heavy metals in the soil samples were determined. The results indicated that the contents ranges of lead(Pb), cadmium(Cd), mercury(Hg), arsenic(As), and chromium(Cr) in the soil samples were 20.90-64.70 mg/kg, 0.035-0.64 mg/kg,0.045-0.44 mg/kg, 7.72-26.32 mg/kg, and 30.8-111.99 mg/kg, respectively. Approximate 43% of the samples exceeded the background contents of soil heavy metals in Hunan Province. Obvious accumulation of heavy metals in soils was observed, especially for Cd and Hg. That the average contents of Cd and Hg in soils were increased by 3.92 and 1.87 times as compared to their background contents, respectively. Moreover, the percentages of Cd and Hg contents in soil samples exceed the limits of GB/T 18407.1—2001 were 35.09% and 24.56%, respectively. The results of zoning evaluation of pollution risk indicated that the long-term vegetable-planted soils in suburb of Changsha city mainly occurred slight heavy metal pollution, and the heavy metals pollution reduced from the inner suburbs to the outer suburbs. Therefore, the heavy metal pollution in the long-term vegetable-planted soils should be paid more attention in the suburb of Changsha city.