Analysis of bioavailability and affecting factors of heavy metals in the soils over Xiaoqinling gold mining region

Analysis of bioavailability and influencing factors of heavy metals in soil is a key to assess the risk management of heavy metal in soil. This study determines the available Hg, Pb, Cd, Cr, As, Cu and Zn in the soils over Xiaoqinling gold mining region, China, using field survey, on-site sampling, testing and comprehensive analysis. It investigates the relationship between available content of the 7 kinds of heavy metals and correlations between available content and total content, and between available content and the basic physical and chemical parameters of the soils such as particle size, soil pH, and organic matter content. The pollution sources of the heavy metals were analyzed by the correlation analysis and the factor analysis. The results show that the average concentrations of the available heavy metals obtained (mg/kg) were Hg 2.289, Pb 2.289, Cd 2.524, Cr 6.304, As 2.159, Cu 6.304, and Zn 2.159. The variation coefficients of available heavy metals were as follows: Hg>Pb>Cu>zinc>As>Cr>Cd. The gold mine development activities, the slag and tailings were the main reason for Hg large variability in the soil of the study area. There was a significant correlation between available Hg, Pb, Cd, Cu, Zn and total amount; there is a significant correlation between soil organic matter and available heavy metal; there is a significant negative correlation between soil pH and available heavy metal; available heavy metal accumulation was not affected by soil particle size.