importance of abiotic reactions for nitrous oxide production

• Published in: Biogeochemistry 2015-12, Vol.126 (3), p.251-267
• Main Authors: Zhu-Barker, Xia, Cavazos, Amanda R, Ostrom, Nathaniel E, Horwath, William R, Glass, Jennifer B
• Format: Article
• Language: English
• Subjects: Abiotic stress; Biogeochemistry; Biogeosciences; Earth and Environmental Science; Earth Sciences; Ecological studies; Ecosystems; Environmental Chemistry; Environmental conditions; environmental factors; enzymatic reactions; Fulvic acids; fungi; hydroxylamine; iron; Isotopes; Life Sciences; Manganese; Manganese compounds; Nitric oxide; nitrites; Nitrogen cycle; Nitrous oxide; Organic compounds; Organic matter; Redox reactions; SYNTHESIS AND EMERGING IDEAS
• ISSN: 0168-2563; 1573-515X
• DOI: 10.1007/s10533-015-0166-4

The continuous rise of atmospheric nitrous oxide (N₂O) is an environmental issue of global concern. In biogeochemical studies, N₂O production is commonly assumed to arise solely from enzymatic reactions in microbes and fungi. However, iron, manganese and organic compounds readily undergo redox reactions with intermediates in the nitrogen cycle that produce N₂O abiotically under relevant environmental conditions at circumneutral pH. Although these abiotic N₂O production pathways have been known to occur for close to a century, they are often neglected in modern ecological studies. In this Synthesis and Emerging Ideas paper, we highlight the defining characteristics, environmental controls, and isotopic signatures of abiotic reactions between nitrogen cycle intermediates (hydroxylamine, nitric oxide, and nitrite), redox-active metals (iron and manganese) and organic matter (humic and fulvic acids) that can lead to N₂O production. We also discuss the emerging idea that abiotic reactions coupled to biotic processes have widespread ecological relevance and encourage consideration of abiotic production mechanisms in future biogeochemical investigations of N₂O cycling.