title: Tracing the sources of nitrate in the Han River watershed in Korea, using delta15N-NO3- and delta18O-NO3- values.
abstract: The dissolved nitrate concentrations and their nitrogen and oxygen isotopic ratios were analyzed in seasonal samples from Korea's Han River to ascertain the seasonal and spatial variations of dissolved nitrate and its possible sources. Nitrate concentrations in the South Han River (SHR) were much higher than those in the North Han River (NHR), probably because of the more extensive distribution of agricultural fields, residential areas and animal farms in the SHR drainage basin. The nitrogen isotopic composition of dissolved nitrate indicates that nitrate-nitrogen (NO(3)(-)-N) is derived mainly from atmospheric deposition and/or soil organic matter in the NHR but comes principally from manure or sewage, with only a minor contribution from atmospheric deposition or soil organic matter, in the SHR. The oxygen isotopic compositions of dissolved nitrate suggest that most atmospheric nitrate undergoes microbial nitrification before entering the river.
authors.affiliation: Korea Basic Science Institute, 52 Eoeun-dong, Yusung-gu, Daejeon 305-333, Republic of Korea. kslee@kbsi.re.kr
authors.forename: Kwang-Sik
authors.initials: KS
authors.lastname: Lee
authors.forename: Yeon-Sik
authors.initials: YS
authors.lastname: Bong
authors.forename: Dongho
authors.initials: D
authors.lastname: Lee
authors.forename: Yongje
authors.initials: Y
authors.lastname: Kim
authors.forename: Kangjoo
authors.initials: K
authors.lastname: Kim
mesh_terms: D004784:Environmental Monitoring / Q000379:methods*; D007723:Korea; D009566:Nitrates / Q000032:analysis*; D009587:Nitrogen Isotopes; D010103:Oxygen Isotopes; D045483:Rivers / Q000737:chemistry*; D012621:Seasons; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D009566:Nitrates; D009587:Nitrogen Isotopes; D010103:Oxygen Isotopes; D014874:Water Pollutants, Chemical