More than methane: quantifying melt-driven biogas production and nutrient export from Eurasian Arctic lowland permafrost (LowPerm)

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In the extensive Arctic sedimentary lowlands two crucial weaknesses undermine our understanding of the biological and physical drivers of regional greenhouse gas (GHG) fluxes: i) poor quantitative understanding of how intrinsic hydrological, geomorphological and ecological factors influence biogas and nutrient recycling/release in the active layer and its interface with the upper permafrostii) poor knowledge on how such changes in permafrost characteristics and function of the active layer influence the adjacent coastal marine ecosystems. The direct and indirect impact of permafrost changes on the Arctic GHG budget can only be reliably predicted when these key problems have been resolved with quantitative estimates. The necessary modelling platforms to quantitatively describe the relevant processes and their interactions within the system already exist, and it is the need for new process understanding to forecast dynamic impacts on climate change that is the most urgent consideration. We have therefore assembled an international multidisciplinary consortium with expertise in hydrology (Solovyanova); permafrost dynamics and geomorphology (Christiansen), biogeochemistry (Hodson and Yde), redox geochemistry (Thornton, Finster) and microbiology (Finster) to provide this information. It is further augmented by leading experts in regional modelling (Romanovsky, De'Ath), ecosystem change and biogeochemistry (Rysgaard, Tranter and Vincent) and isotope geochemistry (Heaton and Bennett), who add significant value as Project Partners. We will conduct an integrated field, laboratory and modelling study of sites from relatively warm Svalbard in Norway, eastwards into colder Siberia, covering the entire Arctic permafrost gradient. We will construct "field observatories" in important thaw environments, including yedoma terraces, ice wedge polygons, raised marine wetlands and deltas. In each case we will collect cores for laboratory studies and conduct field monitoring to construct mass balance models that describe their integrated GHG forcing potential. Laboratory studies will determine (i) how biogeochemical and microbiological conditions change with depth, from the active layer into the permafrost, and (iii) how changing temperature and moisture regimes influence the microbial communities and their functional potential for C and nutrient processing at these depths. In this way we will quantitatively link the biogeochemical conditions to the physical and functional differences between the permafrost types, establishing their potential for microbially-mediated GHG production and nutrient export to marine ecosystems. The potential impact of nutrient and organic matter export from lowland permafrost on marine ecosystem production will then be estimated by amending incubations of sea water with runoff from the different field observatories. Two workshops will provide crucial fora for establishing the integration of permafrost GHG feedbacks into the next generation of regional biogeophysical models, while also allowing our scientific contribution and its wider societal importance to be showcased. We will also establish the field observatories as innovative learning resources for future students visiting the Arctic university of Svalbard.