Soil Methane Production, Anaerobic and Aerobic Oxidation in Porewater of Wetland Soils of the Minjiang River Estuarine, China

Abstract

Wetlands are important sources of methane emission. Methane anaerobic oxidation, aerobic oxidation and production, and dissolved methane are important process of methane metabolism. We studied methane metabolism and the soil influencing factors. Potential soil methane production, anaerobic oxidation and aerobic oxidation rates, and dissolved methane in soil porewater changed seasonally and the annual average was 21.15.1 μg g-1 d-1 , 11.03.9 μg g-1 d-1 , 20.95.8 μg g-1 d-1 , and 62.920.6 μmol l-1 , respectively. Potential soil methane production and anaerobic and aerobic oxidation were positively correlated among them and with soil pH and negatively correlated with soil redox potential (Eh). Potential soil methane production and aerobic and anaerobic oxidation rates were negatively related to pore soil methane concentration. Thus, the more water saturated the soil (the lower Eh), the higher its capacity to methane production was, but even higher was soil potential capacity to methane oxidation both in the same anaerobic circumstances and when the soil was suddenly submitted to aerobic conditions. All these results suggested a buffer effect in the methane balance in wetland areas, the environmental circumstances favoring methane production are also favorable to methane anaerobic oxidation.

Plant‐mediated methane transport in emergent and floating‐leaved species of a temperate freshwater mineral‐soil wetland

“…It is possible that the high concentrations in porewater in our site, have supported constant high concentrations of methane in the lacunae, despite the seasonal variations. The porewater concentrations we found at OWC are 3-20 times higher than the commonly reported in other wetland ecosystems (Chasar et al 2000;Elberling et al 2011;Wang et al 2018). If variations in porewater methane concentrations were not driving seasonal methane plant flow-through fluxes, then…”

Hydrological Conditions Influence Soil and Methane-Cycling Microbial Populations in Seasonally Saturated Wetlands

“…In addition to identifying aerobic methanotrophs, we found that the relative abundance of anaerobic methane oxidizers exceeded aerobic methanotrophs and was approximately 2-5 times greater than the methanogen population (Figure 4). Recent evidence suggests that anaerobic methanotrophs can significantly reduce CH 4 emissions from wetland soils (Smemo and Yavitt, 2011;Segarra et al, 2015;Wang et al, 2018); however, most models and studies do not include these processes or microorganisms in their analysis (Gauthier et al, 2015). While it is unclear how active these communities are in these soils, the phylotypes that we identified, the anaerobic methaneoxidizing archaea (ANME), Candidatus Methanoperedens (formerly classified as ANME-2d), and the anaerobic methaneoxidizing bacterial species, Methylomirabilaceae, suggest that CH 4 consumption and subsequent emissions is linked to and controlled by inorganic N (i.e., nitrite or nitrate) availability.…”

“…In contrast, consumers of CH 4 , or methanotrophs, that play a pivotal role in reducing wetland CH 4 emissions (Chowdhury and Dick, 2013;Segarra et al, 2015) are not restricted to a single phylogenic group; instead, methane oxidation can be performed by many different bacterial and archaeal species. Until recently, methane oxidation was believed to be restricted to oxygen-rich soil environments; however, new evidence suggests that anaerobic oxidation of methane (AOM) may consume a much larger fraction of CH 4 produced in freshwater environments, including wetland soils, than initially expected (Smemo and Yavitt, 2011;Cui et al, 2015;Wang et al, 2018).…”

Three Decades of Wetland Methane Surface Flux Modeling by Earth System Models‐Advances, Applications, and Challenges

“…In contrast to methanogenesis, methanotrophy is processed by one class of microorganisms known as methanotrophs through oxidation, which is responsible for the consumption of a large part of the produced methane (Le Mer & Roger, 2001). Oxidation occurs under both aerobic and anaerobic conditions, where oxidation in the aerobic topsoil uses oxygen as the electron acceptor, while anaerobic oxidation (in wetland sediments, and deeper saturated soil layers) relies on other oxidants, most commonly nitrate or sulfate (Segers, 1998; W. Wang et al., 2018). Methane transport to the atmosphere occurs primarily through three different pathways: (a) molecular diffusion through the soil sediments and water column, (b) ebullition representing the release of methane bubbles trapped under the surface and rapidly emitted to the atmosphere while bypassing oxic soils at the top of the surface (Peltola et al., 2018), and (c) transport through plant aerenchyma, which are internal plant tissues that facilitate gas diffusion (Villa et al., 2021).…”