The future role for Nitrogen in acidification; investigating the changes in N runoff using modeling, empirical and experimen......se 141498

During recent years attention has been drawn upon increased leakage of nitrate from mountain and heathland areas receiving high Nitrogen deposition. Increased leakage of nitrate may cause deterioration of drinking water, acidification of surface waters an d contribute to marine eutrophication. In Norway nitrogen leakage vary between 0 - 40%, with highest values in mountain and heathland areas with high N load. In the latest protocol for reductions of nitrogen emission, critical loads estimates are based on the FAB-model (First-order Acidity Balance). This model gives an estimate of the combined effect of both Sulphur (S) and Nitrogen (N) and predicts a worst case scenario assuming 100% leakage of nitrogen to surface waters as nitrate. The time dynamic aspe ct is of importance, so that future N-reductions can be implemented in the most cost-efficient way. Focus is put on retention processes in the soil in order to reveal relations that are of importance for N-leakage in mountain and heathland areas. The PhD work aims to combine existing data, field experiments and modeling in order to achieve a deeper understanding of factors influencing N-leakage to waters and watercourses.