Global change processes in peatlands: A study of the microbiology and biogeochemistry of reactive nitrogen oxides

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Project Highlights: - New research to unravel the significance of reactive nitrogen oxide (NOy) emissions from a network of UK peatland sites. Understanding peatland NOy is important for human and wider environmental well-being. - A multi-institute supervisory partnership linking to state-of-the-art instrumentation and opportunities for wider collaboration in funded peatland research projects. - A blend of laboratory and field experience, accessing skills ranging from molecular techniques to in-situ trace gas measurement Overview:Peatlands in the UK account for 9.5% of land cover1 and are currently experiencing rapid modifications in response to environmental stimuli such as increased atmospheric nitrogen (N) deposition sourced from human activity. These ecosystems perform a plethora of functions, none more critical than acting as large reservoirs of organic matter (OM). Research has demonstrated that N-deposition may transform these OM stocks into sources of greenhouse gases (CO2, CH4).2 However, to date much less attention has been paid to how enhanced N deposition may also change N-cycling processes that release reactive nitrogen oxides (NOy = NO, NO2, HONO).Reactive nitrogen oxides are greatly understudied and may be emitted at high rates from peatlands, especially under increased N-deposition. NOy gases are categorized as air pollutants causing respiratory distress in humans and can also catalyse reactions that lead to ground level ozone formation and vegetation damage. At larger scales are globally significant as they control the oxidative capacity of the atmosphere, the lifetime of greenhouse gases, and the rate of secondary aerosol formation that directly and indirectly affects climate. While NOy are known products of nitrification and denitrification, a recently identified process involving iron (Feammox) has been suggested as being extremely important for the production and emission of NOy in these ecosystems. Feammox is a microbial process that generally occurs under anoxic conditions of saturated soils such as peatlands, where iron oxides can act as an electron acceptor and play a critical role influencing N reactions in the absence of oxygen. It is suggested that up to 7% loss of N from anaerobic soils3-6 may be mediated by Femmanox but estimates are highly uncertain due to the paucity if research in this area. Thus, there is a critical need to (i) determine the intrinsic ability of UK peatlands to produce NOy, (ii) explore the influence of N-deposition on N-cycle rates in these ecosystems, and (iii) differentiate the mechanisms by which N is transformed in peatlands, paying particular attention to microbe-iron mediate processes.