Microbial arsenic transformations influence methane oxidation, denitrification, and carbon fixation in high-arsenic environments
Photo by National Institute of Allergy and Infectious Diseases / Unsplash
Key Takeaway
Microbial arsenic transformations influence methane, nitrous oxide, and carbon dioxide fluxes in high-arsenic environments.
This narrative review explores the complex interactions between microbial arsenic transformations and greenhouse gas dynamics in specific environmental niches. The scope covers naturally high-arsenic environments where microorganisms drive arsenic mobilization during anaerobic and aerobic methane oxidation. The authors also discuss how incomplete denitrification acts as a significant biological source of nitrous oxide during direct arsenic oxidation.
The review highlights the potential for these environments to serve as a regional net carbon sink through direct arsenic oxidation driving autotrophic carbon fixation. Additionally, indirect feedbacks mediated by arsenic methylation and demethylation are described as regulating downstream methanogenic communities and methane fluxes through detoxification-driven shifts in arsenic speciation.
The authors acknowledge critical knowledge gaps regarding specific molecular pathways and multi-element interactions. These limitations indicate that the mechanistic coupling between arsenic biogeochemical cycling and greenhouse gas levels is not yet fully understood. The review provides a robust scientific foundation for understanding these complex interplays but does not offer clinical practice recommendations.
View Original Abstract ↓
Microorganisms play a pivotal role in driving both arsenic (As) biogeochemical cycling and the significantly anomalous greenhouse gas (GHG) levels frequently observed in naturally high-As environments; however, the mechanistic coupling between these two processes remains insufficiently characterized. This review presents a comprehensive synthesis of the interplay between microbial transformations of As (oxidation, reduction, and methylation/demethylation) and three major greenhouse gases—CH4, N2O, and CO2. We first summarize the key microbial taxa and molecular mechanisms governing As redox transformation, CH4 oxidation and methanogenesis, autotrophic CO2 fixation, and denitrification-driven N2O production. Building on this mechanistic foundation, we elucidate four experimentally and environmentally validated linkages, including (1) direct methane oxidation coupled with As(V) reduction (AOM-AsR), highlighting the molecular mechanisms that drive arsenic mobilization during anaerobic/aerobic methane oxidation and their environmental implications; (2) direct As(III) oxidation coupled with denitrification, linking the As and nitrogen cycles, wherein incomplete denitrification acts as a significant biological source of N2O; (3) direct As(III) oxidation driving autotrophic carbon fixation, offering a potential regional net carbon sink across diverse environments; and (4) indirect feedbacks mediated by As methylation/demethylation and geochemical mobilization, where detoxification-driven shifts in As speciation and local toxicity indirectly regulate downstream methanogenic communities and CH4 fluxes. Finally, we identify critical knowledge gaps regarding specific molecular pathways and multi-element interactions underlying these microbially driven couplings, and propose future research directions centered on deeper mechanistic elucidation. Overall, this review provides a robust scientific foundation for understanding the complex interplay between As biogeochemistry and GHG dynamics in specific environmental niches.
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