Controlling microbial arsenite oxidation and mobilization in arsenite-adsorbed iron minerals: The Influence of pH conditions and mineralogical composition

• Published in: Journal of hazardous materials 2022-07, Vol.433, p.128778-128778, Article 128778
• Main Authors: Cai, Xiaolin, Zhang, Zhennan, Yin, Naiyi, Lu, Wenyi, Du, Huili, Yang, Mei, Cui, Liwei, Chen, Shibao, Cui, Yanshan
• Format: Article
• Language: English
• Subjects: Arsenic - metabolism; Arsenic biogeochemical cycling; Arsenites; As(III)-oxidizing bacteria; Bacteria - metabolism; Bacterial adhesion; Ferric Compounds - chemistry; Ferrosoferric Oxide; Hydrogen-Ion Concentration; Iron - metabolism; Minerals - chemistry; Oxidation-Reduction; Pseudomonas - metabolism; Soil - chemistry; Soil remediation; X-ray absorption spectroscopy
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2022.128778

The oxidation of aqueous arsenite (As(III)) by As(III)-oxidizing bacteria is known to attenuate the mobilization and toxicity of arsenic, and is regarded as potential method for As(III)-pollution remediation. However, during the interactions between As(III)-oxidizing bacteria and different As(III)-adsorbed soil Fe-minerals, the oxidation and partitioning of solid-phase As(III), as well as the controlling mechanisms, remain unclear. In this study, we therefore incubated three As(III)-adsorbed Fe-minerals with a typical As(III)-oxidizing bacteria (Pseudomonas sp. HN-1) at different pH conditions. After microbial oxidation, the percentage of arsenate (As(V)) was significantly higher at pH 7 (15–94%) and 9 (12–89%) than at pH 4 (6–50%) in all Fe-minerals. Incubation of As(III)-oxidizing bacteria promoted As-immobilization under acidic-conditions but As-mobilization under alkaline-conditions. Arsenic-X-ray adsorption spectroscopy results showed that solid-phase As(V) fraction in goethite, hematite and magnetite was 27–64%, 5–12% and 50–91%, respectively. Compared with the corner-sharing As(III)-adsorption complexes formed on magnetite, the edge-sharing complexes on hematite were significantly more stable towards microbial-oxidation. Additionally, the strong adhesion between strain HN-1 and hematite probably limit bacterial-activity and mobility, thereby inhibiting microbial As(III)-oxidation. Our findings elucidate the controlling mechanisms of microbial As(III)-oxidation in different As(III)-adsorbed Fe-minerals and demonstrate strain HN-1 is an excellent candidate for As(III)-remediation in soils containing goethite and magnetite. [Display omitted] •Microbial oxidation of mineral-adsorbed As(III) is magnetite > goethite > hematite.•Edge-sharing (2E) As(III) complexes are more stable towards microbial oxidation.•Strong bacterial adhesion to Fe-minerals may inhibit solid-phase As(III)-oxidation.•Strain HN-1 is an excellent candidate for soil As(III)-remediation.•pH is a critical factor controlling the bioremediation of soil As(III) pollution.