title: Isotopic character of nitrous oxide emitted from streams.
abstract: Global models have indicated agriculturally impacted rivers and streams may be important sources of the greenhouse gas nitrous oxide (N(2)O). However, there is significant uncertainty in N(2)O budgets. Isotopic characterization can be used to help constrain N(2)O budgets. We present the first published measurements of the isotopic character of N(2)O emitted from low (2-4) order streams. Isotopic character of N(2)O varied seasonally, among streams, and over diel periods. On an annual basis, δ(18)O of emitted N(2)O (+47.4 to +51.4‰; relative to VSMOW) was higher than previously reported for larger rivers, but δ(15)N of emitted N(2)O (-16.2 to +2.4‰ among streams; relative to atmospheric N(2)) was similar to that of past studies. On an annual basis, all streams emitted N(2)O with lower δ(15)N than tropospheric N(2)O. Given these streams have elevated nitrate concentrations which are associated with enhanced N(2)O fluxes, this supports the hypothesis that streams are contributing to the accumulation of (15)N-depleted N(2)O in the troposphere.
authors.affiliation: Environmental and Life Sciences Graduate Program, Trent University, 1600 West Bank Drive, Peterborough ON K9J 7B8 Canada. helenmbaulch@gmail.com
authors.forename: Helen M
authors.initials: HM
authors.lastname: Baulch
authors.forename: Sherry L
authors.initials: SL
authors.lastname: Schiff
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Thuss
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Dillon
mesh_terms: D009587:Nitrogen Isotopes / Q000032:analysis; D009609:Nitrous Oxide / Q000737:chemistry*; D010103:Oxygen Isotopes / Q000032:analysis; D045483:Rivers / Q000737:chemistry*
chemical_list: D009587:Nitrogen Isotopes; D010103:Oxygen Isotopes; D009609:Nitrous Oxide