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

Peatlands in the UK account for 9.5% of land cover and are experiencing rapid modifications due to environmental factors such as increased atmospheric nitrogen (N) deposition from human activity. These ecosystems perform critical functions, particularly acting as large organic matter (OM) reservoirs. Research shows that N-deposition may transform these OM stocks into sources of greenhouse gases. However, less attention has been paid to how enhanced N deposition changes N-cycling processes that release reactive nitrogen oxides (NOy = NO, NO2, HONO).

Reactive nitrogen oxides are understudied yet may be emitted at high rates from peatlands, especially under increased N-deposition. NOy gases are air pollutants causing respiratory distress in humans and can catalyse reactions leading to ground-level ozone formation and vegetation damage. Globally, they control the atmosphere's oxidative capacity, greenhouse gas lifetime, and secondary aerosol formation affecting climate.

While NOy are known products of nitrification and denitrification, a recently identified process involving iron (Feammox) may be extremely important for NOy production and emission in peatlands. Feammox is a microbial process occurring under anoxic conditions in saturated soils where iron oxides act as electron acceptors, influencing N reactions in the absence of oxygen. It is suggested that up to 7% of N loss from anaerobic soils may be mediated by Feammox, but estimates remain uncertain due to limited research.

This project aims to: (i) determine UK peatlands' intrinsic ability to produce NOy, (ii) explore N-deposition's influence on N-cycle rates in these ecosystems, and (iii) differentiate mechanisms by which N is transformed in peatlands, with particular attention to microbe-iron mediated processes.