Anaerobic oxidation of methane in coastal wetlands responding to manganese Influenced by soil nitrogen and microbial

Abstract

Manganese-dependent anaerobic oxidation of methane (Mn-AOM) processes that metal-reducing bacteria mediate are coupled with carbon (C) and nitrogen (N) cycles and have a considerable thermodynamic occurrence advantage, playing a major driving force in biogeochemical cycling processes. Under the current study, unknown is how the addition of Mn oxide will impact AOM, as well as the exact mechanisms underlying it that have inconsistent effects. To this end, the Yellow River Delta coastal wetlands were taken as the study region, and this study used laboratory culture methods and molecular biology techniques to examine the response mechanism of the AOM process to Mn input in coastal wetlands. These results showed AOM exhibited various response scenarios in responding to Mn inputs, and the process may depend on soil N content, in addition to the background value of soil Mn content, and these factors are influenced by several microbial factors. After Mn⁴⁺ addition, the microbial diversity of the promotion group (Total nitrogen (TN): 267.3–372.6 mg·kg‾¹) and the no significant effect group (TN: 221.4–476.0 mg·kg‾¹) was higher than that of the inhibition group (TN: 114.4–125.0 mg·kg‾¹). Mn⁴⁺ input increased microbial competition in the inhibition group and inhibited the AOM rate; in the promotion group, the appropriate TN concentration was conducive for Mn⁴⁺ to increase the AOM rate. In the promotion group, microorganisms such as Gemmatimonadota were significantly correlated with the AOM rate; in the inhibition group, Clostridiales and Lautropia were significantly correlated with the AOM rate and Mn⁴⁺ concentration, respectively. This study is important for reducing methane emissions and slowing down the global warming process.