Mapping of Nitrate Reduction Capacities on a Small Scale: Lundgårds Bæk Catchment Area: Master Thesis

This master thesis aims to research and develop a way for estimating the nitrate reduction capacities of a small agriculture-dominated catchment area of first-second order stream (Lundgårds bæk). From landuse management point of view, it would be economically more efficient to use small scale maps instead of the existing national big scale nitrate reduction potential map.
More specific, the goals of this thesis are: to understand the nitrate fate in the catchment area of Lundgårds bæk; to develop a method for estimating the nitrate reduction capacities on a sub-catchment level; and to map critical zones from the catchment area, contributing to the nitrate pollution of Lundgårds bæk.
It was found that the high NO3- concentrations in Lundgårds bæk are caused by NO3- contaminated groundwater and that the measured concentrations differ significantly in the different part of the stream.
The developed nitrate reduction capacity map showed that only around 30% of Lundgårds bæk catchment area has less than 80% NO3- reduction capacity. While, according to the big scale national map the whole catchment falls in the 50-75% reduction potential zone
The mapping of the critical zones illustrated that the leaching from 80% of Lundgårds bæk catchment area is not affecting the water quality of the stream.