Spatial distribution and risk assessment of heavy metal pollution in farmland soil of a lead-zinc mining area
WU Jin-nan1, LONG Jian1, LIU Ling-fei1, LI Juan2, LIAO Hong-kai1, PENG Si-qing3, WAN Hong-fu3
1. Guizhou Provincial Key Laboratory for Information System of Mountainous Areas and Protection of Ecological Environment, Guizhou Normal University, Guiyang 550001, China; 2. Department of Geography and Environmental Science, Guizhou Normal University, Guiyang 550001, China; 3. Guangdong Institute of Eco-Environmental Technology, Guangzhou 510650, China
Abstract:The purpose of this study was to further investigate the general distribution of heavy metal in farmland soils and to identify the possible sources of heavy metals pollution from a lead-zinc mining and smelting area in Zhehai,a town of Huize County.A total of 496topsoil samples were collected and the concentrations of Cd,Hg,Pb,Cu and Zn were determined in all the soil samples.The concentrations of heavy metals in surface soil were interpolated using the Natural Neighbor Interpolation method and three-dimensional models were created to study spatial characteristics of heavy metal pollution in the cropland soils.The degrees of heavy metals pollution were evaluated by using Single Pollution index (PI),Nemero Synthesis Pollution index (NPI) and Potential Ecological Risk index (PER).Principle Component Analysis and Cluster Analysis were used to identify pollution sources.The results showed that the concentrations (mg/kg) of Cd,Hg,Pb,Cu and Zn were 33.05,5.83,12.02,4.89 and 16.33times as compared to soil background values of Yunnan Province,respectively.Spatial distribution of Cd,Hg,Pb and Zn in the cropland soils illustrated that the most seriously polluted region was in the northwest,meanwhile the center was more severe than the other two sides.The concentration of Cu,however,was showed a contrast trend.The results of PI showed that 99.8% of the amount of the soil samples was contaminated by Cd,which reached the heavy pollution level,and was followed by Cu (82.06%) and Zn (62.50%).NPI indicated that the whole study area belonged to heavy pollution degree,and especially in the northwest was the most severe region.PER demonstrated that high risk appeared in the middle while low risk could be found on both sides,which Cd made the greatest contribution to with a ratio of 61%.Correlation analysis revealed that Zn,Cd,Pb and Hg were positively correlated with each other (P<0.01),indicating that these four pollutants might come from the same source.The results of Principal Component Analysis and Cluster Analysis showed that Cd,Hg,Pb and Zn were mainly affected by the mining activities,while Cu was mostly affected by natural factors.Therefore,in order to recover the soil from heavy metal pollution,the impact of both anthropogenic and natural sources should be taken into accounts.
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WU Jin-nan, LONG Jian, LIU Ling-fei, LI Juan, LIAO Hong-kai, PENG Si-qing, WAN Hong-fu. Spatial distribution and risk assessment of heavy metal pollution in farmland soil of a lead-zinc mining area. CHINA ENVIRONMENTAL SCIENCECE, 2018, 38(3): 1054-1063.
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