title: Nitrogen leaching and acidification during 19 years of NH₄NO₃ additions to a coniferous-forested catchment at Gårdsjön, Sweden (NITREX).
abstract: The role of nitrogen (N) in acidification of soil and water has become relatively more important as the deposition of sulphur has decreased. Starting in 1991, we have conducted a whole-catchment experiment with N addition at Gårdsjön, Sweden, to investigate the risk of N saturation. We have added 41 kg N ha(-1) yr(-1) as NH(4)NO(3) to the ambient 9 kg N ha(-1) yr(-1) in fortnightly doses by means of sprinkling system. The fraction of input N lost to runoff has increased from 0% to 10%. Increased concentrations of NO(3) in runoff partially offset the decreasing concentrations of SO(4) and slowed ecosystem recovery from acid deposition. From 1990-2002, about 5% of the total N input went to runoff, 44% to biomass, and the remaining 51% to soil. The soil N pool increased by 5%. N deposition enhanced carbon (C) sequestration at a mean C/N ratio of 42-59 g g(-1).
authors.affiliation: IVL Swedish Environmental Research Institute, Box 5302, SE-40014 Gothenburg, Sweden. filip.moldan@ivl.se
authors.forename: Filip
authors.initials: F
authors.lastname: Moldan
authors.forename: Richard F
authors.initials: RF
authors.lastname: Wright
mesh_terms: D009566:Nitrates / Q000032:analysis* / Q000378:metabolism; D009584:Nitrogen / Q000032:analysis / Q000378:metabolism; D012987:Soil / Q000032:analysis; D012989:Soil Pollutants / Q000032:analysis* / Q000378:metabolism; D013548:Sweden; D014197:Trees / Q000254:growth & development / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000378:metabolism
chemical_list: D009566:Nitrates; D012987:Soil; D012989:Soil Pollutants; D014874:Water Pollutants, Chemical; D009584:Nitrogen; C006568:ammonium nitrate