JES编辑推荐文章：硫酸盐还原菌介导的水铁矿相转化及负载砷的迁移再分配

硫酸盐还原菌介导的水铁矿相转化及负载砷的迁移再分配

Dynamic coupling of ferrihydrite transformation and associated arsenic desorption/redistribution mediated by sulfate-reducing bacteria

Wenjing Zhou, Huiyan Zhu, Shiwen Hu, Bowei Zhang, Kun Gao^*, Zhi Dang, Chongxuan Liu

https://doi.org/10.1016/j.jes.2022.12.007

在自然环境中，硫酸盐还原菌是次生铁矿物和砷地球化学循环的重要驱动者，但是，尚不完全清楚上述反应过程涉及的作用机制。本研究结合地球化学、光谱学、电子显微镜和热力学分析等手段探究了硫酸盐还原菌（脱硫弧菌属, Desulfovibrio vulgaris）介导的水铁矿相转化的特征及负载砷的迁移再分配规律。研究结果表明，D. vulgaris能够通过其代谢产生的S^2-或直接作用驱动水铁矿相转化。在缺乏SO₄^2-时，D. vulgaris会直接作用于水铁矿，导致水铁矿部分相转化为磁铁矿。上述过程中，水铁矿负载的砷释放进入水体后被二次矿物重新吸附。随着SO₄^2-浓度的增大，S^2-驱动水铁矿相转化的作用机制所占权重增加，同时，导致水铁矿的相转化速率增大。在低浓度和中浓度SO₄^2-实验组，水铁矿完全转化为磁铁矿和马基诺矿导致残渣态砷的相对含量增大，这增强了砷稳定性。在高浓度SO₄^2-实验组，尽管水铁矿完全转化为马基诺矿增大了残渣态砷的相对含量，但是，由于马基诺矿固定砷的能力相对较弱，以及As⁵⁺被还原为As³⁺，上述反应过程导致了22.1%的砷释放进入水体。硫酸盐还原菌介导水铁矿还原、相转化的作用机制，以及负载砷的迁移再分配规律与周围环境中SO₄^2-的浓度密切相关。上述研究结果有助于提升我们对Fe、S和As生物地球化学行为的认识，为砷污染的风险评估和治理提供支撑。

揭示了硫酸盐还原菌介导的水铁矿相转化的特征及负载砷的迁移再分配规律。

Sulfate-reducing bacteria play an important role in the geochemistry of iron (oxyhydr)oxide and arsenic (As) in natural environments; however, the associated reaction processes are yet to be fully understood. In this study, batch experiments coupled with geochemical, spectroscopic, microscopic, and thermodynamic analyses were conducted to investigate the dynamic coupling of ferrihydrite transformation and the associated As desorption/redistribution mediated by Desulfovibrio vulgaris. The results indicated that D. vulgaris could induce ferrihydrite transformation via S^2--driven and direct reduction processes. In the absence of SO₄^2-, D. vulgaris directly reduced ferrihydrite, and As desorption and re-sorption occurred simultaneously during the partial transformation of ferrihydrite to magnetite. The increase in SO₄^2- loading promoted the S^2--driven reduction of ferrihydrite and accelerated the subsequent mineralogical transformation. In the low and medium SO₄^2- treatments, ferrihydrite was completely transformed to a mixture of magnetite and mackinawite, which increased the fraction of As in the residual phase and stabilized As. In the high SO₄^2- treatment, although the replacement of ferrihydrite by only mackinawite also increased the fraction of As in the residual phase, 22.1% of the total As was released into the solution due to the poor adsorption affinity of As to mackinawite and the conversion of As⁵⁺ to As³⁺. The mechanisms of ferrihydrite reduction, mineralogy transformation, and As mobilization and redistribution mediated by sulfate-reducing bacteria are closely related to the surrounding SO₄^2- loadings. These results advance our understanding of the biogeochemical behavior of Fe, S, and As, and are helpful for the risk assessment and remediation of As contamination.

第一作者

周文静，硕士研究生，南方科技大学环境科学与工程学院。研究方向：地下水中砷的生物地球化学行为。硕士期间在J. Hazard. Mater., J. Environ. Sci.等期刊发表学术论文4篇。

通讯作者

高坤，研究助理教授（2023-至今），南方科技大学南方科技大学环境科学与工程学院。2021年6月，博士毕业于华南理工大学，随后，在南方科技大学从事博士后研究工作（2017-2021）。研究反向为矿区次生铁矿物的相转化及对重金属归宿的影响。目前，以第一/通讯作者在J. Hazard. Mater., J. Environ. Sci.等期刊发表学术论文11篇，申请专利1项。

https://www.sciencedirect.com/science/article/pii/S1001074222006222

Wenjing Zhou, Huiyan Zhu, Shiwen Hu, Bowei Zhang, Kun Gao, Zhi Dang, Chongxuan Liu, 2024. Dynamic coupling of ferrihydrite transformation and associated arsenic desorption/redistribution mediated by sulfate-reducing bacteria. J. Environ. Sci. 135, 39-50.