Abiotic Methane Production Driven by Soil Reactive Oxygen Species

High Resolution Image Download MS PowerPoint Slide Methane (CH 4 ), which is a potent greenhouse gas, is predominantly produced in wetland soils through biological processes. Recent studies reveal that reactive oxygen species (ROS) can abiotically generate CH 4 via oxidative demethylation of organic compounds; yet, the environmental significance of this pathway remains unexplored. Here, we investigate the potential for reactive oxygen species (ROS)-driven CH 4 formation across diverse wetland soils during redox fluctuations. Using sterilized soils from 14 Chinese wetlands amended with a model methyl donor, we identified a linear relationship between hydroxyl radical (•OH) accumulation and CH 4 production, yielding 91 nmol·L –1 CH 4 per nmol·L –1 •OH. Mechanistic validation with citric acid and sodium citrate demonstrated that ligand-mediated iron chelation and acidification work together to enhance this pathway by preventing iron precipitation. Natural biomaterials, such as fish remnants and rice litter, acted as methyl donor hotspots, contributing approximately 50% of total CH 4 emissions during oxygenation. These findings establish ROS-driven CH 4 production as a pervasive abiotic pathway under ambient conditions. Our results underscore the necessity of reevaluating water management strategies in wetlands, where fluctuating water levels may inadvertently amplify abiotic CH 4 fluxes.