Ion activity and distribution of heavy metals in acid mine drainage polluted subtropical soils |
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Authors: | Yong-Tao Li Thierry Becquer Cécile Quantin |
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Institution: | a College of Natural Resources and Environment, South China Agricultural University, 510642 Guangzhou, China b Laboratoire de Géochimie des Eaux, Université Paris-Diderot - IPGP, Case 7052, Bâtiment Lamarck, 75205 Paris Cedex 13, France c UMR 137 Biodiversité et Fonctionnement des Sols, IRD/Universités Paris VI and XII, SupAgro - Bât. 12, 2 Place Viala, 34060 Montpellier Cedex 2, France d UMR 8148 IDES, Université Paris Sud XI - CNRS, Bat. 504, 91405 Orsay Cedex, France |
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Abstract: | The oxidative dissolution of mine wastes gives rise to acidic, metal-enriched mine drainage (AMD) and has typically posed an additional risk to the environment. The poly-metallic mine Dabaoshan in South China is an excellent test site to understand the processes affecting the surrounding polluted agricultural fields. Our objectives were firstly to investigate metal ion activity in soil solution, distribution in solid constituents, and spatial distribution in samples, secondly to determine dominant environment factors controlling metal activity in the long-term AMD-polluted subtropical soils. Soil Column Donnan Membrane Technology (SC-DMT) combined with sequential extraction shows that unusually large proportion of the metal ions are present as free ion in the soil solutions. The narrow range of low pH values prevents any pH effects during the binding onto oxides or organic matter. The differences in speciation of the soil solutions may explain the different soil degradation observed between paddy and non-paddy soils. |
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Keywords: | Acid mine drainage Free ion Sorption Tropical soils Speciation |
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