title: Evaluation of the origin of nitrate influencing the Ključ groundwater source, Serbia.
abstract: This paper describes the use of the dual isotope method involving δ(15)N and δ(18)O measurements of dissolved nitrates to assess the origin and fate of groundwater nitrate at the Ključ groundwater source, Serbia. A sampling campaign was conducted in September 2007 during flow conditions obtaining groundwater from observation wells and river water fed by a shallow aquifer hosted in alluvial (sandy-gravel) sediments. Nitrate isotope ratios ranged from +5.3 to +16.9‰ and δ(18)O(NO(3)) values varied from -2.3 to +5.0‰. Two major contamination sources were identified with isotopic compositions characteristic for nitrate derived from nitrification of soil organic nitrogen (+5.3 to +7.8‰ for δ(15)N) resulting in nitrate concentrations of 33.6 and 78.8 mg/L and nitrate derived from animal wastes or human sewage, e.g. via septic systems, yielding δ(15)N values of +9.9 to +11.9‰ and elevated nitrate concentrations of 31.2-245.8 mg/L. The occurrence of nitrification and denitrification was also revealed based on concentration and isotope data for dissolved nitrate.
authors: Jaroslav Černi Institute for the Development of Water Resources, Jaroslava Černog 80, Belgrade, Serbia. emiljevi@vinca.rs
authors: Nada
authors: N
authors: Miljević
authors: Djulija
authors: D
authors: Boreli-Zdravković
authors: Vesna
authors: V
authors: Obradović
authors: Dušan
authors: D
authors: Golobočanin
authors: Bernhard
authors: B
authors: Mayer
mesh_terms: D005308:Fertilizers; D005843:Geography; D060587:Groundwater / Q000737:chemistry*; D009566:Nitrates / Q000032:analysis*; D009587:Nitrogen Isotopes; D010103:Oxygen Isotopes; D055771:Serbia; D012995:Solubility; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D005308:Fertilizers; D009566:Nitrates; D009587:Nitrogen Isotopes; D010103:Oxygen Isotopes; D014874:Water Pollutants, Chemical