Accumulation and Evaluation of Arsenic and Mercury in Soils under Different Land Use

In order to explore the heavy metal concentrations and the characteristic of accumulation in different types of agricultural lands in Dujiangyan City, 73 sampling points in topsoil（0-20 cm）were collected for testing the content of arsenic and mercury. The results showed that the average contents of arsenic and mercury were 7.24 mg/kg and 0.29 mg/kg respectively. In comparison with different agricultural lands, the highest concentration for arsenic and mercury appeared in the fruit field with the average content of 8.61 mg/kg for arsenic, 1.105 times higher than background, and the content of mercury was 0.33 mg/kg, which is 1.833 times higher than background. The content of arsenic in different soils ranked in this order: fruit field>paddy field> vegetable field >dry farm, while soil mercury content from high to low in turn for: fruit field> vegetable field >dry farm>paddy field. Though accumulation of arsenic and mercury in soils occurred in different agricultural lands, reference Quality Standard of Soil Environmental the content of arsenic and mercury did not exceed the permitted. Through Geo-accumulation index method and ecological risk index method to evaluate the pollution status of different heavy metals separately, we found that the potential pollution risk of mercury was higher than arsenic, while both of mercury and arsenic were at a slight ecological pollution level in the samplings region.