Properties and Reactivity of Iron-Organic Matter-Arsenic Composites and their Influence on Arsenic Behavior in Microbial Reduction and Oxidation Processes
Year: 2025
Type: article
Abstract: The biogeochemistry of arsenic in soils is strongly controlled by iron oxides and soil organic matter (SOM). The present study intends to elucidate the behavior of arsenic in Fe-SOM-As composites formed through adsorption or coprecipitation under redox conditions. The X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM) showed that crystalline minerals were generated during Fe-HA-As coprecipitation, while other composites exhibited an amorphous structure. In an anoxic environment, iron-reducing bacteria reduced Fe(III) and As(V) to Fe(II) and As(III), respectively, enhancing the mobility of arsenic. The presence of SOM increased the concentrations of dissolved Fe(II) and As(III) through complexation. Notably, elevated As(III) and reduced Fe(II) were observed in the HA-containing coprecipitation group due to the weak adsorption capacity of crystalline minerals, which released As(V) into solution and competed with Fe(III) for electrons. Under oxic conditions, superoxide, hydrogen peroxide, and hydroxyl radical ( • OH) were formed through the oxidation of Fe(II) and reduced SOM. As(III) was subsequently oxidized by superoxide and • OH, and the process was dominated by • OH. Substantial • OH in the HA-containing coprecipitation group mainly oxidized dissolved As(III), while limited • OH in other groups contributed greater to adsorbed As(III). These findings contribute substantially to understanding the mechanisms of the coupled transformation of iron and arsenic in soil under fluctuating redox conditions.
Authors: Ruixia Han, Zhe Wang, Jitao Lv, Kaiwen He, Siyao Liu, Zhe Zhu, Jerome Nriagu, H. Henry Teng, Yong-Guan Zhu, Gang Li
Institutions: Chinese Academy of Sciences, Institute of Urban Environment, Research Center for Eco-Environmental Sciences, State Key Laboratory of Environmental Chemistry and Ecotoxicology, University of Nottingham Ningbo China, University of Nottingham, University of Michigan, Tianjin University, State Key Laboratory of Urban and Regional Ecology
Language: English
Subfield: Environmental Chemistry
Field: Environmental Science
Domain: Physical Sciences
Open Access status: bronze
Funders: School of Public Health, University of Michigan, Department of Science and Technology, Ministry of Science and Technology, India, National Natural Science Foundation of China, Chinese Academy of Sciences, Natural Science Foundation of Fujian Province, Tianjin University, State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, National Postdoctoral Program for Innovative Talents, Institute of Urban Environment, Chinese Academy of Sciences, Ningbo Municipal Science and Technology Innovative Research Team
OpenAlex ID: W4408937488