Pollution characteristics and environmental quality assessment of Cd-Pb-As in soil of abandoned mining area in Guangxi
In this paper,38 soil samples,from 9 sites of 0-20 cm(surface layer)and 20-60 cm(deep layer)and 2 soil profiles in an abandoned rare earth mining area in Guangxi,are collected and analyzed.The pollution status and potential ecological risk of Cd,Pb and As are evaluated by using the geo-accumulation index method and potential ec-ological risk index model.The result is shown as follows.(1)The heavy metal content of Cd and Pb in topsoil and deep soil exceeds the standard obviously,especially the content of Cd exceeds the standard seriously.The over-stand-ard rate of Cd are both more than 100％and that of Pb is 33.3％and 22.2％,respectively.(2)The correlation anal-ysis of the three heavy metal elements indicates that the correlation between Cd and Pb is not obvious,but the corre-lation between Cd and As is very significant.(3)The pollution assessment shows that heavy metal element Cd is at a moderate pollution level in the surface soil,Pb is at a mild pollution level,and Cd and Pb are both at a moderate pollution level in the deep soil,and As element shows no pollution in the surface and deep soil.(4)The Igeo values of As in 0-100 cm sections of the mining and non-mining area are less than-1,which belongs to non-pollution grade.The pollution degree of heavy metals of Cd and Pb in non-mining area is lower than that in mining area.In the range of mining area,the contents of Cd and Pb increase firstly and then decrease with the increase of soil depth,and reach the highest values at the depth of 40 cm,and there is no obvious change regularity of the contents of Cd and Pb in non-mining area.
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