Research Interests Bianca Torres Liguori Pires

Biogeochemical cycling of Silicon in the Arctic Ocean

Silicon is a major element and an important nutrient mainly for diatoms. Diatoms are important primary producer that take up dissolved Si from the water to build a siliceous skeleton and that are responsible for the production of the majority of organic carbon in the oceans, which shows the importance of diatoms in both the global carbon and Si cycles. The stable Si isotope composition of different reservoirs like seawater or diatoms bears information on the dominant pathways and processes by which Si is transported to and cycled within the ocean. In most oceanic regions, the Si isotope composition of water masses vary as a function of input from land, primary productivity of diatoms in surface waters and the dissolution of their skeletons in deeper waters, and physical water mass circulation and mixing. The Arctic Ocean is a unique environment characterized by low biological productivity and highly seasonal Si utilization, extended shelf areas, high river discharge yet low particle fluxes, and seasonal sea-ice cover. This work is going to provide a baseline study on the present day Si isotope distribution in the Arctic for a better understanding of the general biogeochemistry of Si in the ocean and for future evaluation of the impact of climate change on the Si cycle.