Environmental Factors Affecting Chromium-Manganese Oxidation-Reduction Reactions in Soil

作     者：D.O.P.TREBIEN L.BORTOLON M.J.TEDESCO C.A.BISSANI F.A.O.CAMARGO D.O.P.TREBIEN 1,L.BORTOLON 2,M.J.TEDESCO 2,C.A.BISSANI 2 and F.A.O.CAMARGO 2 1 Department of Agricultural Engineering,Federal University of Santa Catarina,Florian’opolis,SC 88040-900(Brazil) 2 Department of Soil Science,Federal University of Rio Grande do Sul,Porto Alegre,RS 90040-060(Brazil)

作者机构：Department of Agricultural EngineeringFederal University of Santa Catarina Department of Soil ScienceFederal University of Rio Grande do Sul 

出 版 物：《Pedosphere》 (土壤圈（英文版）)

年 卷 期：2011年第21卷第1期

页      面：84-89页

核心收录：

学科分类：083002[工学-环境工程] 0830[工学-环境科学与工程（可授工学、理学、农学学位）] 08[工学] 

基　　金：Supported by the Soil Testing Laboratory Project Federal University of Rio Grande do Sul Brazil 

主　　题：cobalt Cr(VI) oxidation Mn oxides soil moisture tannery sludge 

摘      要：Disposal of chromium （Cr） hexavalent form, Cr（Ⅵ）, in soils as additions in organic fertilizers, liming materials or plant nutrient sources can be dangerous since Cr（Ⅵ） can be highly toxic to plants, animals, and humans. In order to explore soil conditions that lead to Cr（Ⅵ） generation, this study were performed using a Paleudult （Dystic Nitosol） from a region that has a high concentration of tannery operations in the Rio Crande do Sul State, southern Brazil. Three laboratory incubation experiments were carried out to examine the influences of soil moisture content and concentration of cobalt and organic matter additions on soil Cr（Ⅵ） formation and release and manganese （Mn） oxide reduction with a salt of chromium chloride （CrCl3） and tannery sludge as inorganic and organic sources of Cr（Ⅲ）, respectively. The amount of Cr（Ⅲ） oxidation depended on the concentration of easily reducible Mn oxides and the oxidation was more intense at the soil water contents in which Mn（Ⅲ/Ⅳ） oxides were more stable. Soluble organic compounds in soil decreased Cr（Ⅵ） formation due to Cr（Ⅲ） complexation. This mechanism also resulted in the decrease in the oxidation of Cr（Ⅲ） due to the tannery sludge additions. Chromium（Ⅲ） oxidation to Cr（Ⅵ） at the solid/solution interface involved the following mechanisms： the formation of a precursor complex on manganese （Mn） oxide surfaces, followed by electron transfer from Cr（Ⅲ） to Mn（Ⅲ or Ⅳ）, the formation of a successor complex with Mn（Ⅱ） and Cr（Ⅵ）, and the breakdown of the successor complex and release of Mn（Ⅱ） and Cr（Ⅵ） into the soil solution.