Abstract/Summary

Executive summary Nature of the problem • Anthropogenic increase of nitrogen in water poses direct threats to human and aquatic ecosystems. High nitrate concentrations in drinking water are dangerous for human health. In aquatic ecosystems the nitrogen enrichment produces eutrophication, which is responsible for toxic algal blooms, water anoxia, fish kills and habitat and biodiversity loss. • The continuous nitrogen export to waters reduces the capacity of aquatic ecosystems to absorb, reorganise and adapt to external stress, increasing their vulnerability to future unexpected natural or climate events. Key findings/state of knowledge • Nitrogen concentrations in European rivers, lakes, aquifers and coastal waters are high in many regions. In addition nitrate concentrations water increasing in groundwaters, threatening the long term quality of the resource. • In Europe, nitrogen pressures occur over large areas, implying elevated costs for meeting the long-term good chemical and ecological water quality requirements. A significant part of the European population could be potentially exposed to high nitrate values in drinking water if adequate treatments were not in place. Furthermore many of European aquatic ecosystems are eutrophic or at risk of eutrophication. • Nitrogen pressures have reduced biodiversity and damaged the resilience of aquatic ecosystems and continue to pose a threat to the aquatic environment and to the provision of goods and services from the aquatic ecosystems. • Even under favourable land use scenarios the nitrogen export to European waters and seas is likely to remain significant in the near future. The effects of climate change on nitrogen export to water are still uncertain. Major uncertainties/challenges • Policy tools are available within the European Union and under international conventions to mitigate the nitrogen pollution in water, but their full implementation has not been achieved yet throughout Europe. • In many cases a delay in the water quality response to the implementation of measures have been observed, due to previous nitrogen accumulation in soils, sediments or aquifers or to inadequate design of the mitigation plans. • The issue of pollution swapping between environmental compartments has appeared as an important element to be considered by both the scientific and policy perspective. Recommendations • To protect and enhance the European water resources the full implementation of the existing regulations related to nitrogen is necessary, in addition to an efficient environmental monitoring. • Moreover, positive synergies could be obtained by encouraging the integration in the sectoral policies and enhancing interdisciplinarity in the scientific research, especially in support of regional assessments and pollution swapping evaluations