Pilot Investigation On Heavy Metal Contaminants In Soil In Huainan Coal-Mine Area

This paper focus on the investigation of hazardous heavy metals in soil in Huainan coal-electricity-chemical industrial district A case study on heavy metals in soil was conducted through the investigation of five soil sampling routes nearby coal-mining spoil dump and coal combustion ash disposal pond in new coal-mining district (i.e. Xinji coal-mining district) and Quanshan chemical industry district respectively. Soil Samples were taken systematically from land in above districts and were digested by HNO₃+HClO₄+HF, and 21 trace elements were analyzed by IRIS Intrepid inductively coupled plasma—atomic emission spectrometry (ICP-AES) in the Institute of Soil Science, CAS, and certified lake sediment samples(LKSD-l) from Energy Mines and Resource Canada were used for analytical quality control. 6 trace elements (Co,Cr, Cu, Ni, Pb, Zn) of environmental interest were selected scientifically and their contaminations were assessed with a variety of methods (i.e. total content standard comparison, correlation coefficient, Enrichment factor). The results indicate that Co,Cu,Ni in Xinji coal-mining district and Co,Ni in Quanshan chemical industrial district present their richment and contamination;the contents of all six elements in soils nearby coal combustion ash are higher than that nearby coal-mining spoils in Xinji coal-mining district Regarding to the contamination of soil nearby coal-mining spoils in whole coal-mining areas, coal mining activities contribute greatly to heavy metal contamination of the soil and the metals accumulate. Moreover, the concentration of heavy metals decreases with the history of mining and weathering of the coal-mining spoils, showing their stronger mobility, especially with Co, Cu, Zn, Ni and Pd. Their contents in some soil were higher above the first-grade criteria for soil pollution established by the SEPA. However, none of them surpass the second-grade criteria, indicating that the translocation of the heavy metals resulting from the exploition and utilization of Huianan coal resources to their surrounding soil is a slow process.Meanwhile, the bioavailability and mobility of the selected heavy metals in typical soil samples were assessed by BCR three-steps sequential extraction procedure, soil certified reference materials (BCR—701) were used for analytical quality control. The result shows that Co and Cu are associated with exchangeable fractions, which represents stonger mobility;Pb in iron-manganese fraction represents stonger potential mobility;Zn and Cr existed in oxidizable and residual fraction and Ni in residues represents weak mobility or immobility. Hence, further assessment of ecological risk of heavy metals should be paid attention in the construction of eco-agriculture in Huainan coal-mine areas.