Effects of policy measures implemented in Denmark on nitrogen pollution of the aquatic environment

Abstract

Abstract Since 1985, seven national Action Plans (AP) have been implemented in Denmark to reduce nitrogen discharges from point sources and nitrogen losses from agriculture. The instruments applied include regulations on point source discharges from waste water treatment plants, area-related measures, e.g. reestablishment of wetlands and afforestation and nutrient-related measures, e.g. mandatory fertilizer plans and improved utilization of nitrogen in manure. A national monitoring programme was launched in 1988 to monitor trends in nitrogen losses from point sources and diffuse agricultural sources. Four national indicators were defined: nitrogen discharges from point sources, nitrogen surplus in agriculture, nitrogen leaching from agricultural land and nitrogen concentrations and loads in surface waters. Since the introduction of mitigation programmes, discharges of nitrogen from point sources have been reduced by 74% (1989–2003), nitrogen surplus by 31% (1990–2003), and model calculated nitrogen leaching from the root zone on agricultural land by 33% (1989–2002). Trend analysis of total nitrogen concentrations and loads in 86 streams draining smaller agricultural catchments shows an average respective reduction of 29 and 32% (1989–2004). The change in model calculated nitrogen leaching varies between 28 and 44% as calculated for catchments within eight geo-regions covering most of Denmark. The average trend calculated for nitrogen concentrations measured in the same streams and geo-regions shows a reduction in total nitrogen concentration between 8 and 45%. The instruments and measures adopted in Denmark to regulate nitrogen losses from different pressures have therefore proven successful. The impact of the regulations are, however, not equally high in all geo-regions which is possibly related to delays in travel time in groundwater. Until now, the regulation has been performed on a national scale. A more regional or local approach is believed to be necessary in future to meet the demands of the EU Water Framework Directive.