Marine sediments and seafloor nutrient cycling in a changing Arctic

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Sediments are key components of all marine ecosystems. In marine sediments, a dynamic interplay of biogeochemical processes is fuelled by the deposition of particulate material, as well as the diffusion of dissolved species from the overlying water column. This interplay transforms a substantial part of the deposited material and, thus, recycles nutrients, dissolved inorganic carbon, and alkalinity back into the water column. These benthic recycling fluxes can exert an important influence on pelagic primary production and ocean acidification.Past research has indicated that the coupling between benthic and pelagic processes is particularly intense on Arctic shelves. The Arctic Ocean is subject to strong seasonal to long-term fluctuations in, among other factors, temperature and sea-ice extent and, so, deposition fluxes, bottom water conditions and bioturbation. Despite its importance for marine ecosystems, the benthic response to such strong seasonal and long-term fluctuations in the Arctic remains underexplored.The aim of this project is to identify the most important controls on the timing and magnitude of benthic biogeochemical processes and fluxes under fluctuating environmental conditions in the Arctic Ocean on both seasonal and climate relevant timescales. The student will use Reaction-Transport Models (RTMs) to explore this challenge by conducting comprehensive sensitivity studies and by carrying out fully transient simulations and model inter-comparisons. The student will also be able to generate their own geochemical records using samples collected in the field from Arctic and other high-latitude field expeditions, in order to carry out a data-model comparison study.