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Abstract Nitrous oxide (N2O) is a climate-active gas with emissions predicted to increase due to agricultural intensification. Microbial reduction of N2O to dinitrogen (N2) is the major consumption process but microbial N2O reduction under acidic conditions is considered negligible, albeit strongly acidic soils harbornosZgenes encoding N2O reductase. Here, we study a co-culture derived from acidic tropical forest soil that reduces N2O at pH 4.5. The co-culture exhibits bimodal growth with aSerratiasp. fermenting pyruvate followed by hydrogenotrophic N2O reduction by aDesulfosporosinussp. Integrated omics and physiological characterization revealed interspecies nutritional interactions, with the pyruvate fermentingSerratiasp. supplying amino acids as essential growth factors to the N2O-reducingDesulfosporosinussp. Thus, we demonstrate growth-linked N2O reduction between pH 4.5 and 6, highlighting microbial N2O reduction potential in acidic soils.
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Kinetics of nitrous oxide mass transfer from porewater into root aerenchyma of wetland plants
Abstract The creation and/or restoration of wetlands is an important strategy for controlling the release of reactive nitrogen (N) via denitrification, but there can be tradeoffs between enhanced denitrification and the production of nitrous oxide (N2O), a potent greenhouse gas. A knowledge gap in current understanding of belowground wetland N dynamics is the role of gas transfer through the root aerenchyma system of wetland plants as a shortcut emission pathway for N2O in denitrifying wetland soils. This investigation evaluates the significance of mass transfer into gas‐filled root aerenchyma for the N2O budget in wetland mesocosms planted withSagittaria latifoliaWilld. andSchoenoplectus acutus(Muhl. ex Bigelow) Á. Löve & D. Löve. Dissolved gas tracer push–pull tests with N2O and the nonreactive gas tracers helium, sulfur hexafluoride, and ethane were used to estimate first‐order rate constants for gas transfer into roots and microbial N2O reduction and thereby disentangle the effects of root‐mediated gas transport from microbial metabolism on N2O balances in saturated soils. Root‐mediated gas transport was estimated to account for up to 37% of overall N2O removal from the wetland soils. Rates of microbial N2O reduction varied widely based on the organic matter content of the soil media and served as a key control on the fraction of N2O that transferred into roots. This research identifies transport through root aerenchyma as a potential shortcut pathway for N2O emission from wetland soils and sediments and indicates that this process should be considered in both measurements and mechanistic modeling of belowground wetland N dynamics.
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- Award ID(s):
- 1804975
- PAR ID:
- 10359809
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Journal of Environmental Quality
- Volume:
- 49
- Issue:
- 6
- ISSN:
- 0047-2425
- Format(s):
- Medium: X Size: p. 1717-1729
- Size(s):
- p. 1717-1729
- Sponsoring Org:
- National Science Foundation
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