title: Effect of iron oxide reductive dissolution on the transformation and immobilization of arsenic in soils: New insights from X-ray photoelectron and X-ray absorption spectroscopy.
abstract: The geochemical behavior and speciation of arsenic (As) in paddy soils is strongly controlled by soil redox conditions and the sequestration by soil iron oxyhydroxides. Hence, the effects of iron oxide reductive dissolution on the adsorption, transformation and precipitation of As(III) and As(V) in soils were investigated using batch experiments and synchrotron based techniques to gain a deeper understanding at both macroscopic and microscopic scales. The results of batch sorption experiments revealed that the sorption capacity of As(V) on anoxic soil was much higher than that on control soil. Synchrotron based X-ray fluorescence (μ-XRF) mapping studies indicated that As was heterogeneously distributed and was mainly associated with iron in the soil. X-ray absorption near edge structure (XANES), micro-X-ray absorption near edge structure (μ-XANES) and X-ray photoelectron spectroscopy (XPS) analyses revealed that the primary speciation of As in the soil is As(V). These results further suggested that, when As(V) was introduced into the anoxic soil, the rapid coprecipitation of As(V) with ferric/ferrous ion prevented its reduction to As(III), and was the main mechanism controlling the immobilization of As. This research could improve the current understanding of soil As chemistry in paddy and wetland soils.
authors: Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; School of River and Ocean Engineering, Chongqing Jiaotong University, Chongqing 400074, China.
authors: Jian-Xin
authors: JX
authors: Fan
authors: Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China. Electronic address: yjwang@issas.ac.cn.
authors: Yu-Jun
authors: YJ
authors: Wang
authors: Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China.
authors: Cun
authors: C
authors: Liu
authors: Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of sciences, Shanghai 201204, China.
authors: Li-Hua
authors: LH
authors: Wang
authors: Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of sciences, Shanghai 201204, China.
authors: Ke
authors: K
authors: Yang
authors: Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China. Electronic address: dmzhou@issas.ac.cn.
authors: Dong-Mei
authors: DM
authors: Zhou
authors: Environmental Soil Chemistry Group, Delaware Environmental Institute and Department of Plant and Soil Sciences, University of Delaware, Newark, DE 19717-1303 United States.
authors: Wei
authors: W
authors: Li
authors: Environmental Soil Chemistry Group, Delaware Environmental Institute and Department of Plant and Soil Sciences, University of Delaware, Newark, DE 19717-1303 United States.
authors: Donald L
authors: DL
authors: Sparks
mesh_terms: D000327:Adsorption; D001151:Arsenic / Q000737:chemistry*; D005290:Ferric Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D056951:Photoelectron Spectroscopy; D012989:Soil Pollutants / Q000737:chemistry*; D012995:Solubility; D017356:Synchrotrons; D056928:X-Ray Absorption Spectroscopy
chemical_list: D005290:Ferric Compounds; D012989:Soil Pollutants; C000499:ferric oxide; D001151:Arsenic
keywords: As(III); As(V); Iron oxides; Reductive dissolution; XAS