Degradation and transformation of lacustrine organic nitrogen compounds: microbiology and biogeochemistry

Transformation of organic matter in aquatic systems is governed by bacterial activity. Particulate material produced by organisms present in the water column is partly degraded by bacteria in the water column and/or sinks to the sediment. We investigate processes related to degradation by analyzing mainly amino sugars and amino acids, organic nitrogen compounds present in algae, animal tissue and bacteria. Some amino sugars are particularly interesting since they are only present in bacterial cell wall. On the other hand amino acids could give information about sources and trophic levels. Determinations of the nitrogen and carbon isotopic compositions of these molecules together with investigations of the bacterial populations will contribute to a better understanding of the degradation processes in the water column and in the underlying sediments.
Our research focuses on two lakes (Lake Zug and Lake Brienz).

Funding

• Swiss National Science Foundation (SNSF)