School of Environmental Science and Engineering, Yancheng Institute of Technology, Yancheng 224051, China; Jiangsu Provincial Key Laboratory of Coastal Ecology and Pollution Control, Yancheng 224051, China.
School of Environmental Science and Engineering, Yancheng Institute of Technology, Yancheng 224051, China; Jiangsu Provincial Key Laboratory of Coastal Ecology and Pollution Control, Yancheng 224051, China.
Sci Total Environ. 2020 Jul 20;727:138630. doi: 10.1016/j.scitotenv.2020.138630. Epub 2020 Apr 13.
Arsenic (As) pollution in coastal wetland soil has attracted attention. However, how anaerobic microbes impact the fate of As in coastal wetland environments remains poorly understood. To elucidate underlying mechanisms of anaerobic microbes mediated As mobilization, incubation experiments were performed in this study. The results demonstrate that the concentrations of total dissolved As and As(III) were higher in biotic incubations compared with abiotic controls. The dissolved As(III) concentrations increased and reached maximum values of 11.0 ± 1.2 and 12.0 ± 1.1 μg/L for biotic incubations with and without additional sulfate, respectively. Sulfate and Fe reduction induced by anaerobic microbes were evidenced by the detection of sulfide and Fe(II) in biotic incubations. The sequential extraction results indicated that the content of crystalline Fe mineral fraction of As (As) increased and that of amorphous Fe mineral fraction of As (As) decreased in the solid phase. Therefore, the released As was attributed to microbially mediated reductive dissolution of amorphous Fe mineral matter and, after 40 days of incubation, the decreased As might be immobilized via re-adsorption onto, or co-precipitation with, the newly formed crystalline Fe minerals. The 16S rRNA results indicated that Proteobacteria, Chloroflexi, Actinobacteria, and Firmicutes constituted the majority of the bacterial community in biotic incubations. The sulfate-reducing bacterium Desulfocapsa induced sulfate reduction and further promoted the reduction and release of As in soils. This study provides insights into the mechanism for As mobilization and redistribution in coastal wetland soils.
砷（As）污染已引起了沿海湿地土壤的关注。然而，目前仍不清楚厌氧微生物如何影响沿海湿地环境中砷的命运。为了阐明厌氧微生物介导砷迁移的潜在机制，本研究进行了孵育实验。结果表明，与非生物对照相比，生物孵育中总溶解态砷和砷（III）的浓度更高。添加硫酸盐的生物孵育中溶解态砷（III）浓度增加，并分别达到 11.0±1.2 和 12.0±1.1μg/L 的最大值。硫酸盐和铁的还原是由厌氧微生物引起的，这可以通过生物孵育中检测到的硫化物和 Fe(II)得到证明。顺序提取结果表明，砷（As）的结晶铁矿物相的含量增加，而砷（As）的非晶铁矿物相的含量减少。因此，释放的砷归因于微生物介导的非晶态铁矿物的还原溶解，经过 40 天的孵育后，减少的砷可能通过重新吸附到或与新形成的结晶铁矿物共沉淀而被固定。16S rRNA 结果表明，生物孵育中的细菌群落主要由变形菌门、绿弯菌门、放线菌门和厚壁菌门组成。硫酸盐还原菌脱硫弧菌诱导硫酸盐还原，并进一步促进了土壤中砷的还原和释放。本研究为了解沿海湿地土壤中砷的迁移和重新分布机制提供了新的见解。
