Stable Isotopes Reveal Widespread Anaerobic Methane Oxidation Across Latitude and Peatland Type

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• 作者：Varun Gupta ; Kurt A. Smemo ; Joseph B. Yavitt ; David Fowle ; Brian Branfireun ; Nathan Basiliko
• 刊名：Environmental Science & Technology (ES&T)
• 出版年：2013
• 出版时间：August 6, 2013
• 年：2013
• 卷：47
• 期：15
• 页码：8273-8279
• 全文大小：279K
• 年卷期：v.47,no.15(August 6, 2013)
• ISSN：1520-5851

文摘

Peatlands are an important source of the atmospheric greenhouse gas methane (CH₄). Although CH₄ cycling and fluxes have been quantified for many northern peatlands, imprecision in process-based approaches to predicting CH₄ emissions suggests that our understanding of underlying processes is incomplete. Microbial anaerobic oxidation of CH₄ (AOM) is an important CH₄ sink in marine sediments, but AOM has only recently been identified in a few nonmarine systems. We used ¹³C isotope tracers and followed the fate of ¹³C into CO₂ and peat in order to study the geographic extent, relative importance, and biogeochemistry of AOM in 15 North American peatlands spanning a 1500 km latitudinal transect that varied in hydrology, vegetation, and soil chemistry. For the first time, we demonstrate that AOM is a widespread and quantitatively important process across many peatland types and that anabolic microbial assimilation of CH₄鈥揅 occurs. However, AOM rate is not predicted by CH₄ production rates and the primary mechanism of C assimilation remains uncertain. AOM rates are higher in fen than bog sites, suggesting electron acceptor constraints on AOM. Nevertheless, AOM rates were not correlated with porewater ion concentrations or stimulated following additions of nitrate, sulfate, or ferric iron, suggesting that an unidentified electron acceptor(s) must drive AOM in peatlands. Globally, we estimate that AOM could consume a large proportion of CH₄ produced annually (1.6鈥?9 Tg) and thereby constrain emissions and greenhouse gas forcing.