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RESEARCH PRODUCT

Modelling the Effects of Climate Change on the Supply of Inorganic Nitrogen

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Human-induced changes in the nitrogen cycle due to the increased use of artificial fertilisers, the cultivation of nitrogen-fixing crops and atmospheric deposition have made nitrogen pollution to surface waters a long-standing cause for concern. In Europe, legislation has been introduced to minimise the risk of water quality degradation from excessive nitrogen inputs e.g., the European Union Nitrates Directive (EU, 1991), Drinking Water Directive (EU, 1998) and Water Framework Directive (EU, 2000). Coastal regions in particular have been an important focus, since coastal eutrophication has been attributed to increased fluxes of nitrogen from the landscape (Howarth et al., 1996; Boesch et al., 2006). While nitrogen is typically not the limiting nutrient in inland waters, increases in the nitrogen supply to rivers and lakes can impact the N:P ratio, influence the structure of aquatic food webs (Elser and Urabe, 1999; Arbuckle and Downing, 2001), regulate the seasonal development of phytoplankton (Van den Brink et al., 1993) and promote the growth of aquatic macrophytes (Kirchmann et al., 2004).