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GSI Seminar: UK peatland pyrogenic carbon characteristics & degradation trends by Oscar Kennedy Blundell

UK peatlands have a long history of prescribed burning and are periodically subjected to wildfires. Whilst peatland fires may release significant amounts of carbon if peat is combusted, there is also the potential for incompletely combusted vegetative biomass (pyrogenic carbon or PyC) to contribute to long term carbon storage. Using laboratory produced PyC samples, my thesis research aimed to improve the understanding of UK peatland PyC, specifically focussing on: (i) the characteristics of the PyC formed in peatland fires; (ii) how these characteristics change with terrestrial exposure; (iii) how degradation of PyC affects water quality; and (iv) how combined terrestrial and aquatic processes alter PyC characteristics. Fuel type and burn severity significantly influenced PyC composition, including elemental, molecular and physical characteristics. Fuel type and burn severity also had significant effects on observed degradation trends in both terrestrial and aquatic settings. Some of the key observed degradation trends included a pulse of leachable carbon early in sample exposure (i.e. ≤1 month), with longer term exposure having strong indications of soil matrix interactions. Based on the findings of this research, fire events in UK peatlands might be expected to lead to rapid increases in carbon fluxes at the peat surface and in nearby rivers. However, these losses of carbon may be balanced by long term soil matrix interactions subsequently increasing PyC stability.