title: Use of (15)N-labelled nitrogen deposition to quantify the source of nitrogen in runoff at a coniferous-forested catchment at Gårdsjön, Sweden.
abstract: To determine the source of dissolved inorganic nitrogen (N) in runoff, approx. 35kg N enriched with the stable isotope (15)N (2110 per thousand delta(15)N) was added to a mature coniferous forested catchment for one whole year. The total N input was approx. 50kg ha(-1) year(-1). The enrichment study was part of a long-term whole-catchment ammonium nitrate addition experiment at Gårdsjön, Sweden. The (15)N concentrations in precipitation, throughfall, runoff and upper forest floor were measured prior to, during, and 3-9years following the (15)N addition. During the year of the (15)N addition the delta(15)N level in runoff largely reflected the level in incoming N, indicating that the leached NO(3)(-) came predominantly from precipitation. Only 1.1% of the incoming N was lost during the year of the tracer addition. The cumulative loss of tracer N over a 10-year period was only 3.9% as DIN and 1.1% as DON.
authors.affiliation: Norwegian Forest and Landscape Institute, Postboks 115, As, Norway. janne.kjonaas@skogoglandskap.no
authors.forename: O Janne
authors.initials: OJ
authors.lastname: Kjønaas
authors.forename: Richard F
authors.initials: RF
authors.lastname: Wright
mesh_terms: D000393:Air Pollutants / Q000032:analysis; D004784:Environmental Monitoring / Q000379:methods; D004785:Environmental Pollutants / Q000032:analysis*; D009566:Nitrates / Q000032:analysis; D009584:Nitrogen / Q000032:analysis*; D009587:Nitrogen Isotopes / Q000032:analysis; D000644:Quaternary Ammonium Compounds / Q000032:analysis; D011891:Rain; D012989:Soil Pollutants / Q000032:analysis; D013548:Sweden; D064028:Tracheophyta / Q000737:chemistry*; D014197:Trees / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: D000393:Air Pollutants; D004785:Environmental Pollutants; D009566:Nitrates; D009587:Nitrogen Isotopes; D000644:Quaternary Ammonium Compounds; D012989:Soil Pollutants; D014874:Water Pollutants, Chemical; D009584:Nitrogen