Authors: Guannan Liu Juan Wang Erxi Zhang Jing Hou Xinhui Liu
Publish Date: 2016/01/23
Volume: 23, Issue: 9, Pages: 8709-8720
Abstract
Heavy metal contamination of soils has been a longstanding 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 468 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 pollutionsThe research was financially supported by the Public Sector Special Scientific Research Program of National Environmental Protection Ministry NO 201309049 and the Multiobjective Geochemical Investigation Program of Beneficial Elements in Enrichment Region NO 12120113000100 We sincerely thank Dr Wei Zhang at Michigan State University for helping with the manuscript revision and constructive suggestions
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