Research On Spatial Distribution And Contamination Sources Of Heavy Metal Cu, Ni, As, Zn, Cr In Huainan Mining Area Based On GIS

The heavy metals pollution is the most important factor that affects the soil environment. Besides, it endangers human health through a variety of ways directly or indirectly. Mining activity often causes heavy metal pollution in soil environment.To identify the spatial structures and distributions of five soil heavy metals (Cu, Ni, As, Zn and Cr) within Huainan mining area, the data were processed and analyzed based on GIS and Geostatistic methods. In addition, pollution assessments of the five soil heavy metal and their source identifications were performed.The results are as follows:(1) 269 soil samples were collected in Huainan Mining Area, and the concentrations of the five soil heavy metals were measured. The five heavy metals have accumulated in the soil within Huainan mining area. Zn is the most polluted element in Huainan mining area; nearly 66.7% sampling points show Zn is heavily contaminated.(2) The spatial structure characters of the five heavy metals in study area were analyzed through the Geostatistic and semi-variogram methods. It was showed that the academic models of Cu and Zn are Gaussian; the models of Ni and Cr are Exponential; the model of As is Spherical. The nugget coefficients of Cu and Cr are under 25%, which showed that Cu and Cr have strong spatial correlation, and the spatial variabilities are affected by soil internal factors. Besides, the nugget coefficients of Ni, As and Zn are between 25% and 75%, which showed that Ni, As and Zn have a medium spatial correlation and are affected by soil internal factors and external factors such as human activities.(3) Nemero Index and the Potential Ecological Risk Index were used to evaluate soil heavy metal pollution. Cu, As, Zn and Cr are the primary elements causing soil pollutions. The Nemero indices of the five elements indicate that the slight and moderate accumulated area covers 71.78% of the study area, while serious accumulated area occupies 12.73%. The Potential Ecological Risk Indices of the five heavy metals show that moderately and highly polluted area covers a total area of 72.64%, seriously polluted area covering 12.73%.(4) The human mining and agricultural activities might be the main sources of soil heavy metals of Cu, Ni, Zn and Cr, As content may be originated from industrial activities. Vertisol and yellow-cinnamon soils are the most polluted soil types in Huainan mining area. The longer the history of mining area, the more harmful the ecological risk. Subsidence area, urban land and farmland are the most polluted landuse in Huainan mining area. The results indicate that soil heavy metal pollutions may be originated from human mining activities, industrial activities and the excessive use of pesticides and fertilizers.