Postdoctoral Research

Research interests: fluxes and degradation of organic matter in marine sediments, the sediment-water interface (fluffy layers), and within biogenic aggregates.

Projects:

Sulfate reduction rates in the Gotland Basin, Baltic Sea.

This work was part of an ongoing multidisciplinary project (OXYDYN). It involved (1) measurements of sulfate and ammonium concentration in interstitial water samples and (2) modeling of sulfate reduction rates in order to determine benthic mineralization processes of particulate matter in anoxic sediments (Hille et al., in prep.).

Differential microbial degradation of particulate organic matter in a shallow water system.

This is my current research project at the Department of Marine Sciences at Chapel Hill, North Carolina, U.S.A. The project is funded by the German Research Foundation (DFG webpage) in collaboration with Carol Arnosti (UNC) and Cindy Lee (Stony Brook University, N.Y.).

Summary of the research proposal:

In coastal environments, the sediment and water column act as a closely coupled system. In both compartments, physical transport processes and geochemical reactions influence the composition of particulate and dissolved organic matter. Aggregates are thereby of major importance. Their significance is due to increased sinking velocity and to the formation of microbial microenvironments, with properties differing considerably from those of the surrounding water.This project aims to evaluate microbial degradation of particulate organic carbon (POC) and nitrogen (PON) in the water column and at the sediment-water interface. Fluorescently-labeled macromolecules as organic substrates will be used to measure microbial hydrolysis rates. The focus will be on processes in fluffy layer material at the sediment-water interface that includes aggregated, particulate organic matter (POM) originated from the upper water column together with particles resuspended from the sea floor. Investigation will provide a better understanding of particulate and dissolved organic matter dynamics in coastal waters.