Composition of molecular organic matter pools, pigments and proteins, in Benguela Upwelling and Arctic sediments

The major objective of this thesis was to assess the application of organic carbon degradation indices and proxies. This work focused on the joint application of the analysis of organic carbon pools, pigments and proteins, andtheir related degradation indices, the Chlorin Index (CI) and the amino acid based Degradation Index (DI) that characterize the reactivity of organic material. Reactivity was defined as the availability of organic carbon tomicrobial degradation in sediments. Molecular degradation indices and proxies were applied to assess organic carbon reactivity in sediments of the Benguela upwelling system and Arctic shelf (Spitzbergen), both of which are characterized by high primaryproductivity. Degradation indices were compared to rates of microbial sulfate reduction as this is a dominant terminal electron acceptor process and thus represents a measure of the current availability of organic carbon tomicroorganisms.Major goals of this study were the definition of time frames and potential application boundaries of molecular degradation indices as well as to explore the link between organic matter composition and carbon mineralisation.