School of Civil and Environmental Engineering, Cornell University, Ithaca, NY 14853, USA.
School of Civil and Environmental Engineering, Cornell University, Ithaca, NY 14853, USA.
Sci Total Environ. 2022 Apr 20;818:151696. doi: 10.1016/j.scitotenv.2021.151696. Epub 2021 Nov 16.
Flooded soils are important environments for the biomethylation and subsequent volatilization of arsenic (As), a contaminant of global concern. Conversion of inorganic to methylated oxyarsenic species is thought to be the rate-limiting step in the production and emission of volatile (methyl)arsines. While methanogens and sulfate-reducing bacteria (SRB) have been identified as important regulators of methylated oxyarsenic concentrations in anaerobic soils, the effects of these microbial groups on biovolatilization remain unclear. Here, microcosm and batch incubation experiments with an Arkansas, USA, rice paddy soil were performed in conjunction with metabolic inhibition to test the effects of methanogenic activity on As speciation and biovolatilization. Inhibition of methanogenesis with 2-bromoethanesulfonate (BES) led to the accumulation of methylated oxyarsenic species, primarily dimethylarsinic acid (DMAs(V)), and a four-fold increase in As biovolatilization compared to a control soil. Our results support a conceptual model that methanogenic activity suppresses biovolatilization by enhancing As demethylation rates. This work refines understanding of biogeochemical processes regulating As biovolatilization in anaerobic soil environments, and extends recent insights into links between methanogenesis and As metabolism to soils from the mid-South United States rice production region.
受淹土壤是砷（As）生物甲基化和随后挥发的重要环境，砷是全球关注的污染物。人们认为，无机砷向甲基化含氧砷物种的转化是产生和排放挥发性（甲基）胂的限速步骤。尽管已经确定产甲烷菌和硫酸盐还原菌（SRB）是厌氧土壤中甲基化含氧砷浓度的重要调节剂，但这些微生物群对生物挥发的影响仍不清楚。在这里，我们结合代谢抑制作用，进行了美国阿肯色州水稻田的微宇宙和批量培养实验，以测试产甲烷活性对砷形态和生物挥发的影响。用 2-溴乙磺酸盐（BES）抑制产甲烷作用导致甲基化含氧砷物种的积累，主要是二甲基砷酸（DMAs（V）），与对照土壤相比，As 的生物挥发增加了四倍。我们的结果支持了一个概念模型，即产甲烷活性通过增强 As 脱甲基速率来抑制生物挥发。这项工作深化了对调节厌氧土壤环境中 As 生物挥发的生物地球化学过程的理解，并将最近关于产甲烷作用与 As 代谢之间联系的见解扩展到美国中南部水稻种植区的土壤。
