Colloquium: Stephan M. Kraemer

Stephan M. Kraemer

Univ. Prof. Dr., Department of Environmental Geosciences, University of Vienna

Abstract:  Iron is the fourth-most abundant element in the earth crust, it is one of the most abundant electron acceptors in microbial metabolism and it plays a major role in core biochemical processes of all known organisms. Therefore, it represents an important link between element cycles and biological processes in the earth system. This link is demonstrated by the limitation of primary productivity of large ocean areas due to the low bioavailability of iron in the photic zone. Similarly, low bioavailability of iron in soils can limit terrestrial biological activity. In both marine and terrestrial systems iron limited organisms actively modify the iron geochemistry in order to maintain intracellular iron homeostasis.

This presentation will take a geochemical perspective of the molecular processes that mediate biological iron acquisition and in turn influence iron cycling. Mechanisms and rates of relevant processes at the mineral water interface will be discussed including photochemical, reductive, and ligand promoted mineral weathering. And it will be discussed how these processes influence iron cycling in such diverse environments as the marine water column and glacial forefields in the Swiss Alps.