Non-microbial methane formation in oxic soils

Abstract

Methane plays an important role as a radiatively and chemically active gas in our atmosphere. Until recently, sources of atmospheric methane in the biosphere have been attributed to strictly anaerobic microbial processes during degradation of organic matter. However, a large fraction of methane produced in the anoxic soil layers does not reach the atmosphere due to methanotrophic consumption in the overlaying oxic soil. Although methane fluxes from aerobic soils have been observed an alternative source other than methanogenesis has not been identified thus far. <br><br> Here we provide evidence for non-microbial methane formation in soils under oxic conditions. We found that soils release methane upon heating and other environmental factors like ultraviolet irradiation, and drying-rewetting cycles. We suggest that chemical formation of methane during degradation of soil organic matter may represent the missing soil source that is needed to fully understand the complete methane cycle within the pedosphere. Although the emission fluxes are relatively low when compared to those from wetlands, they may be important in warm and wet regions subjected to ultraviolet radiation. We suggest that this methane source is highly sensitive to global change

Widespread production of nonmicrobial greenhouse gases in soils

“…Accordingly, Hurkuck, Althoff, Jungkunst, Jugold, and Keppler () first reported with direct evidence NM‐CH 4 production in aerobic soils. This finding is further confirmed by following studies (Gu et al., ; Jugold et al., ; Wang, Hou, Liu, & Wang, ).…”

A novel pathway of direct methane production and emission by eukaryotes including plants, animals and fungi: An overview

“…This non-microbial process is sensitive to a variety of environmental factors. It is of particular interest that the addition of water significantly enhanced CH 4 emissions Jugold et al, 2012). These findings revealed an unexpected ecological importance of soil to the global CH 4 cycle.…”

“…Three recent studies reported a "missing" source of CH 4 from oxic soils Jugold et al, 2012;Wang et al, 2013a). With a pretreatment that inhibits methanogenic activity, soils release CH 4 under oxic conditions.…”

Increasing Methane Emissions From Natural Land Ecosystems due to Sea‐Level Rise

“…Second, the effect of dams needs to be incorporated in future hydrological modeling as water level regulation may change hydraulic gradient at outlets, in turn, altering inundation extent. Third, previous studies (Jugold et al, ; Megonigal et al, ) also showed that CH 4 may be produced in oxic soils. With better understanding of this process, the inclusion of CH 4 emissions from unsaturated soils will contribute the CH 4 emission modeling due to the SLR.…”