State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, P.R. China.
Institute of Earth Sciences, China University of Geosciences (Beijing), Beijing 100083, P.R. China.
Environ Sci Technol. 2021 Nov 16;55(22):15181-15195. doi: 10.1021/acs.est.1c04117. Epub 2021 Oct 28.
Biogeochemical processes critically control the groundwater arsenic (As) enrichment; however, the key active As-mobilizing biogeochemical processes and associated microbes in high dissolved As and sulfate aquifers are poorly understood. To address this issue, the groundwater-sediment geochemistry, total and active microbial communities, and their potential functions in the groundwater-sediment microbiota from the western Hetao basin were determined using 16S rRNA gene (rDNA) and associated 16S rRNA (rRNA) sequencing. The relative abundances of either sediment or groundwater total and active microbial communities were positively correlated. Interestingly, groundwater active microbial communities were mainly associated with ammonium and sulfide, while sediment active communities were highly related to water-extractable nitrate. Both sediment-sourced and groundwater-sourced active microorganisms (rRNA/rDNA ratios > 1) noted Fe(III)-reducers (induced by ammonium oxidation) and As(V)-reducers, emphasizing the As mobilization via Fe(III) and/or As(V) reduction. Moreover, active cryptic sulfur cycling between groundwater and sediments was implicated in affecting As mobilization. Sediment-sourced active microorganisms were potentially involved in anaerobic pyrite oxidation (driven by denitrification), while groundwater-sourced organisms were associated with sulfur disproportionation and sulfate reduction. This study provides an extended whole-picture concept model of active As-N-S-Fe biogeochemical processes affecting As mobilization in high dissolved As and sulfate aquifers.
生物地球化学过程对地下水砷（As）的富集会产生关键性的影响；然而，在富含溶解态 As 和硫酸盐的含水层中，关键的主动砷活化生物地球化学过程及其相关微生物仍然知之甚少。为了解决这个问题，本研究采用 16S rRNA 基因（rDNA）和相关的 16S rRNA（rRNA）测序技术，测定了河套西部盆地地下水-沉积物地球化学、总微生物群落和活性微生物群落及其在地下水-沉积物微生物组中的潜在功能。无论沉积物还是地下水总微生物群落和活性微生物群落的相对丰度均呈正相关。有趣的是，地下水活性微生物群落主要与铵和硫化物有关，而沉积物活性微生物群落与水可提取硝酸盐密切相关。沉积物源和地下水源的活性微生物（rRNA/rDNA 比值＞1）都注意到铁（III）还原剂（由铵氧化诱导）和 As(V)还原剂，强调了通过 Fe(III) 和/或 As(V)还原来活化 As。此外，地下水和沉积物之间的隐式硫循环的活性被认为会影响 As 的活化。沉积物源的活性微生物可能参与了厌氧黄铁矿氧化（由反硝化作用驱动），而地下水源的微生物与硫歧化和硫酸盐还原有关。本研究提供了一个扩展的、全面的高溶解态 As 和硫酸盐含水层中影响 As 活化的主动 As-N-S-Fe 生物地球化学过程的概念模型。
