Spatial Distribution Characteristics and Ecological Risk Assessment of Heavy Metals in Farmland Soil of a Mining Area
Received:August 18, 2020   Revised:August 31, 2020   Accepted:September 01, 2020      Published Online:February 22, 2021
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DOI:doi:10.3969/j.issn.1007-7545.2021.03.015
KeyWord:coal mine area; farmland soil; heavy metal pollution; spatial distribution;risk assessment
     
AuthorInstitution
LI Wu-jiang 贵州民族大学喀斯特湿地生态研究中心
ZHU Si-xi 贵州民族大学喀斯特湿地生态研究中心
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Abstract:
      To explore distribution characteristics and pollution degree of heavy metals in farmland around a mining area in Liupanshui, Guizhou province, surface soil was collected with farmland around mining area as the research object. Contents of Cr, Ni, Cu, Pb, Zn and As are analyzed, and their spatial distribution characteristics, heavy metals pollution and potential ecological risk and their source in the study area were also studied. The results show that soil heavy metals element content in the study area are higher than soil background values of heavy metals in Guizhou province, excessive multiples of Cu (5.82) > Ni (2.52) > zinc (2.46) > Pb (1.81) Cr (1.51) > As (1.18). Heavy metal distribution shows that heavy metals accumulation is more serious in coal gangue mountain and farmland soil around the washing plant. Mean single pollution index to display level of Cu in severe pollution, Ni and Zn for light pollution level, Pb, Cr and As for slight pollution level, and comprehensive pollution situation is in the severe pollution level. The evaluation results of geological accumulation index method show that Cu, Ni, Zn and Pb are slightly polluted, while Cr and As are clean. Comprehensive potential ecological risk index of heavy metals is 68.02, which has reached the degree of mild harm, among which Cu and Ni contribute the most to comprehensive potential ecological risk (RI). The results of multivariate statistical analysis show that correlation between Zn and Pb, Zn with As and Cu with Pb is strong, indicating that sources of Zn, Pb, As and Cu are similar. As the first source, they are mainly from three wastes produced by mining activities. Ni and Cr are the second and third sources respectively. The second heavy metals source is related to automobile exhaust emission and mechanical loss. The third heavy metals source is mainly affected by soil parent material. The results of four evaluations are basically consistent. Farmland soil around mining area is severely polluted and slightly damaged. Cu and Ni are the most significant ecological risk factors affecting soil in research area, and heavy metals are mainly derived from three wastes from mining activities.
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