European scenario studies on future in-stream nutrient concentrations

摘要

Large-scale water quality issues have recently become the focus of policy and research. To gain insight into large-scale water quality issues, a scenario analysis was carried out for Europe using the continental water quality model WorldQual with total nitrogen and phosphorus as example pollutants. Future nitrogen and phosphorus loadings and instream concentrations were simulated for an “economy first” scenario and compared to contemporary conditions. Results indicate that future total nitrogen (TN) loadings are likely to decrease in most parts of central Europe by 5 to 25 kg ha-1 year-1 due to land-use change in the form of reduced cropland area as a result of technological changes, as well as improvements in land-use management based on higher efficiencies of application rates. Climate change has less impact on TN loadings, but an increase of future in-stream concentrations is accompanied by reduced river discharge. Future total phosphorus (TP) loadings are similar to contemporary loadings for all of Europe. In-stream TP concentrations do not change in northern and eastern Europe. In central Europe, concentrations increase little (by one class). In a few regions,such as northern Spain, very high changes (up to more than three classes) are apparent as a result of reduced river discharge.