Assoc. Prof. Dr. Laura Wehrmann 

The role of reverse weathering for element cycling in glacially impacted Arctic fjords

Over long time scales, the inputs of major and minor elements to the ocean by rivers and hydrothermal vents must be balanced by removal mechanisms of these elements in the marine realm in order for ocean chemistry to remain relatively constant. A long-debated process that sequesters elements in ocean sediments is reverse weathering which involves the transformation of biogenic silica, such as diatom frustules, to new clay material. However, many aspects of this process still remain unknown, such as reaction rates and products and global distribution. Previous studies of this process have focused on tropical deltaic systems. Coastal polar regions, including glacially influenced fjords, likely represent another hotspot of reverse weathering because they receive high inputs of key “ingredients”: biogenic silica and reactive Fe- and Al-oxides. The aim of this project is to study the role of reverse weathering in glacially influenced fjords with focus on identifying a set of key geochemical indicators in the fjord sediments and developing estimates of associated element fluxes across the sediment-water interface. Polar coastal ocean regions are currently undergoing rapid changes due to anthropogenic climate shifts. A further objective of this project is to gain first insights into how climate change may affect reverse weathering processes in these environments.