Brief description

The percentage of diffuse nitrogen-loads in streams increased during the last years especially in the intensive agricultural lands. Diffuse sources are all these entries in the stream, which doesn't come from the local WWTPs. An increase in the natural in-stream degradation of nitrogen can help to reduce this loads. That's why the aim of this study is the quantification of the natural nitrate degradation (denitrification) in small streams in the pleistocene lowlands. Especially slow flowing streams have a quiet high potential for nitrogen degradation. The influence of seasonal and stream morphological factors and of the near stream vegetation on nitrogen degradation in nitrate rich streams will be investigated by the connection of isotope hydrology and mathematical modelling of processes.

Tasks

• Inference of the nitrate degradation in the body of water by field investigations in a small typical stream of the North-German lowlands
• Based on the experimental results a suitable modelling approach, which describe transformation processes in the body of water with special attention at the nitrate degradation at the sediment-water-interface, will be parameterized and calibrated.
• Investigation of the relation between stream morphology, bottom substrate, macrophytes and the nitrate degradation under different seasonal conditions. Identification of sensitive factors. Deduction of measures supporting N-retention in small streams in the lowlands of Northern Germany.