Do Glaciers Enhance Organic Carbon Burial?: An Isotopic Approach Linking Continental Weathering, Iron-(oxhydr)oxides and Climate Change.

Abstract

This thesis explores continental weathering patterns in glacial and non-glacial river catchments in Iceland and Greenland. Specific attention is placed on characterizing the relative iron (oxyhydr)oxide export rates of glacial and non-glacial catchments to the ocean. Total element concentration and iron stable isotope measurements indicate that chemical weathering differences do exist between glacial and non-glacial catchments. The differences appear primarily related to variations in soil formation and organic matter availability between the environments. Physical, rather than chemical, differences between glacial and non-glacial catchments however dominate the relative differences in (oxyhyr)oxide export rates. Glacial and non-glacial river sediments from otherwise analogous terrains contain about the same quantity of iron (oxyhyr)oxide on a weight normalized basis. This equates to glacial rivers exporting far more iron (oxyhyr)oxides on a discharge weighted basis, because glacial rivers contain far higher suspended sediment concentrations that non-glacial rivers. Existing research shows that organic carbon accumulation and burial in marine environments scale directly with iron (oxyhydr)oxide accumulation. This means that shifts in continental weathering over glacial-interglacial cycles drive further changes in marine carbon burial creating a global climate feedback loop.