Fraction Distribution and Risk Assessment of Heavy Metals in Soils around the Mining Area in Zhijin

摘要

The pollution characteristics of Cd,Cr,Cu,Zn,Ni and Hg in agricultural soil around coal mining area were studied. After longterm mining activity,the soil around mining area was polluted by 6 elements to different degrees. Especially for Cd,its concentration was 3. 2times that of the National Soil Environmental Quality Standard Ⅱ. The values suggest that the contamination degree from strong to weak in soil is in the order of Hg > Cu > Cr > Zn > Ni > Cd. BCR sequential extraction results show that the order of average percentage about weak acid soluble fraction( F1) is that Cd > Ni > Zn > Cu > Hg > Cr,the order of 6 heavy metals available fraction( F1 + F2 + F3) is that Cu( 56. 89) > Cd( 50. 95) > Ni( 41. 52) > Zn( 35. 06) > Hg( 23. 04) > Cr( 4. 88). The RAC results indicate that soils were in a moderate potential ecological risk by pollution of Cd,and at the same time,Cu,Zn,Ni,Hg should be noted.