ONE Planet DTP - Assessing the extent of permafrost degradation in Western Siberia using geochemical markers. (OP20285)

Permafrost-affected peatlands contain large quantities of organic carbon which can decompose to form carbon dioxide (CO2) and methane (CH4). Climate change is affecting the microbial decomposition of peatlands, both through increased temperature and waterlogging (Schuur et al. 2015). Simultaneously, permafrost is vulnerable to thaw and the release of CH4 to the atmosphere can exacerbate the greenhouse effect (Frey and Smith 2005; Knoblauch et al. 2018). Siberia is especially vulnerable as it contains a large C pool within peatlands of ~70 Pg C (Sheng et al. 2004). To assess the extent of peatland decomposition with burial depth and areal cover, organic geochemical techniques including pyrolysis-gas-chromatography-mass-spectrometry (Py-GC-MS) can be used to understand the degradation mechanisms of Sphagnum-derived peat through characterisation of lignin and other Sphagnum-derived phenolics (Abbott et al. 2013; Schellekens et al. 2015; Mason et al. 2009). The student will use our collaborative links with Tomsk State University to compare discontinuous Arctic region permafrost with peatlands in the middle taiga zone. The student will also have access to a comparative UK peatland (Butterburn Flow, Northumberland). Py-GC-MS using tetramethylammonium hydroxide (TMAH) will be applied to samples collected form peat cores from each study site (discontinuous Arctic permafrost zone and middle taiga zone) with analyses focused on zones of major botanical change (as advised by I. Volkova Tomsk State University) and at the acrotelm-catotelm interface (transition from living to decaying plant matter). Total organic carbon (TOC) will be conducted to provide insight into zones of key carbon accumulation and provide correction for the pyrolysis measurements. Bulk C:N ratios will provide insight into the relative woody vegetation versus Sphagnum contribution to the peat cores. This will be further explored with lignin phenol source and degradation proxies including syringyl/guaiacyl, cinnamyl/guaiacyl ratios and total amounts of phenolics. Analytical skills will be gained in the measurement of methane fluxes and organic geochemical techniques including GC-MS.