Periodic Reporting for period 1 - ICE-OTOPE (“Weathering and nutrient export from subglacial environments: A novel stable isotope approach”)
Reporting period: 2015-11-02 to 2017-11-01
Predicting the impact of future ice-sheet and glacier behavior depends upon a clear understanding of how glacier dynamics relate not only to climatic driving forces but also to subglacial processes. The overarching goal of ICE-OTOPE is to investigate the subglacial conditions that control elemental release through a study of glacial outflows which vary fundamentally in size, hydrology and bedrock composition. To achieve this goal I proposed to use a novel multidisciplinary framework utilizing cutting-edge geochemical techniques, fieldwork and geochemical modeling to investigate the chemistry of subglacial systems. Through ICE-OTOPE new constraints on element cycling in glacial systems have been produced which can be used to enhance our understanding of the key processes that have governed the Earth’s chemical evolution and biogeochemical cycling.
A particular emphasis was placed on the element Fe, Fe-isotopes, and the coupled sulfur-Fe biogeochemical cycle. Using the analytical-modeling techniques above I was able to broadly determine in what conditions Fe is released in different subglacial systems around the Arctic, how much of the Fe is bioavailable and its fate downstream in glacial rivers. One of the key findings is that the concentration of Fe (and other elements) from glaciers draining different regions of the Greenland Ice Sheet (and other regions of the Arctic) span orders of magnitude. Therefore a huge amount of care must be taken when calculating elemental and nutrient fluxes from regions such as the Greenland Ice Sheet into the proximal oceans.
A comprehensive assessment of weathering products (i.e. the dissolved and suspended elemental fluxes) from recently deglaciated landscapes is severely lacking from the literature. It is still unknown whether warming temperatures will lead to a net increase in biological productivity. This fundamental question must be addressed before further assessment of the impact of climate change on chemical weathering and associated CO2 drawdown. By characterizing the weathering products of many different glacial systems, the data generated by ICE-OTOPE will continue to fill these missing gaps to provide crucial information and constraints on the chemical weathering processes in subglacial systems and their exported products, and thus climate evolution.