Climate warming causes permafrost thaw predicted to increase toxic methylmercury (MeHg) and greenhouse gas [i.e., methane (CH₄), carbon dioxide (CO₂), and nitrous oxide (N₂O)] formation. A microcosm incubation study with Arctic tundra soil over 145 days demonstrates that N₂O at 0.1 and 1 mM markedly inhibited microbial MeHg formation, methanogenesis, and sulfate reduction, while it slightly promoted CO₂ production. Microbial community analyses indicate that N₂O decreased the relative abundances of methanogenic archaea and microbial clades implicated in sulfate reduction and MeHg formation. Following depletion of N₂O, both MeHg formation and sulfate reduction rapidly resumed, whereas CH₄ production remained low, suggesting that N₂O affected susceptible microbial guilds differently. MeHg formation strongly coincided with sulfate reduction, supporting prior reports linking sulfate-reducing bacteria to MeHg formation in the Arctic soil. This research highlights complex biogeochemical interactions in governing MeHg and CH₄ formation and lays the foundation for future mechanistic studies for improved predictive understanding of MeHg and greenhouse gas fluxes from thawing permafrost ecosystems.

中文翻译：

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一氧化二氮对北极苔原土壤微观世界中甲基汞和甲烷形成的抑制作用

气候变暖导致永久冻土融化，预计会增加有毒甲基汞 (MeHg) 和温室气体 [即甲烷 (CH ₄ )、二氧化碳 (CO ₂ ) 和一氧化二氮 (N ₂ O)] 的形成。对北极苔原土壤进行超过 145 天的微观世界孵化研究表明，0.1 和 1 mM 的N _{2 O 显着抑制微生物甲基汞的形成、甲烷生成和硫酸盐还原，同时略微促进 CO 2 的}产生。微生物群落分析表明，N ₂ O 降低了与硫酸盐还原和甲基汞形成有关的产甲烷古菌和微生物进化枝的相对丰度。_{N 2}耗尽后O，甲基汞的形成和硫酸盐的还原都迅速恢复，而 CH ₄的产量仍然很低，这表明 N ₂ O 对易感微生物群的影响不同。甲基汞的形成与硫酸盐的还原密切相关，支持先前的报道将硫酸盐还原细菌与北极土壤中的甲基汞形成联系起来。这项研究强调了控制甲基汞和 CH ₄形成的复杂生物地球化学相互作用，并为未来的机制研究奠定了基础，以改进对永久冻土生态系统融化中甲基汞和温室气体通量的预测理解。