title: Heavy metal speciation and risk assessment in dry land and paddy soils near mining areas at Southern China.
abstract: Heavy metal contamination of soils has been a long-standing environmental problem in many parts of the world, and poses enormous threats to ecosystem and human health. Speciation of heavy metals in soils is crucial to assessing environmental risks from contaminated soils. In this study, total concentrations and speciation of As, Cd, Cr, Cu, Mn, Ni, Pb, and Zn were measured for agricultural soils near mines along the Diaojiang River in Guangxi Zhuang Autonomy Region, China. The sources of heavy metals in soils also were identified to assess their effect on speciation distribution of soil heavy metals. Furthermore, the speciation distribution of Cd and Zn, main soil heavy metal pollutants, in dry land and paddy soils were compared. Results showed that there were two severely polluted regions near mine area reaching alarming pollution level. As, Cd, Pb, and Zn were more affected by mining activities, showing very strong pollution level in soils. The mean percentage of exchangeable and carbonate fraction was highest and up to 46.8 % for Cd, indicating a high environmental risk. Greater bioavailable fractions of As, Cd, Cu, Mn, Pb, and Zn were found in soils heavily polluted by mining activities, whereas Cr and Ni as geogenic elements in the stable residual fraction. In addition, in the dry land soils, reducible fraction proportion of Cd was higher than that in the paddy soils, whereas exchangeable and carbonate fraction of Cd was lower than that in the paddy soils. Oxidizable fraction of Zn was higher in the paddy soils than that in the dry land soils. The results indicate that the sources of soil heavy metals and land types affect heavy metal speciation in the soil and are significant for environmental risk assessment of soil heavy metal pollutions.
authors.affiliation: State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing, 100875, People's Republic of China.|Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing, 100037, People's Republic of China.
authors.forename: Guannan
authors.initials: G
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing, 100875, People's Republic of China.
authors.forename: Juan
authors.initials: J
authors.lastname: Wang
authors.affiliation: Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing, 100037, People's Republic of China.|College of Management Science, Chengdu University of Technology, Chengdu, 610059, People's Republic of China.
authors.forename: Erxi
authors.initials: E
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing, 100875, People's Republic of China.
authors.forename: Jing
authors.initials: J
authors.lastname: Hou
authors.affiliation: State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing, 100875, People's Republic of China. xhliu@bnu.edu.cn.
authors.forename: Xinhui
authors.initials: X
authors.lastname: Liu
mesh_terms: D002681:China; D017753:Ecosystem; D004784:Environmental Monitoring; D006801:Humans; D019216:Metals, Heavy / Q000032:analysis*; D008906:Mining; D018570:Risk Assessment; D012987:Soil; D012989:Soil Pollutants / Q000032:analysis*
chemical_list: D019216:Metals, Heavy; D012987:Soil; D012989:Soil Pollutants
keywords: Heavy metal; Land type; Mine; Soil; Source; Speciation