Department Surface Waters - Research and Management

Stable nitrogen isotopes


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. Transformation from particulate to dissolved organic material is investigated in the water column using Fourier transform ion cyclotron resonance mass spectrometer (15 Tesla FT-ICR MS, University Oldenburg). Furthermore, we investigate degradation processes by analyzing amino sugars and amino acids, organic nitrogen compounds, present in the water column. 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. Additionally, determinations of the nitrogen and carbon isotopic compositions of these molecules help to better understand degradation processes in the water column and in the underlying sediments.

Our research focuses on two lakes (Lake Zug and Lake Lucerne).