1 results for Addy, K.

  • Dynamics of nitrous oxide in groundwater at the aquatic-terrestrial interface

    Clough, T.; Addy, K.; Kellog, D.; Nowicki, B.; Gold, A.; Groffman, P.

    Journal article
    Lincoln University

    Few data are available to validate the Intergovernmental Panel on Climate Change's emission factors for indirect emissions of nitrous oxide (N₂O). In particular the N₂O emissions resulting from nitrogen leaching and the associated groundwater and surface drainage (EF5-g) are particularly poorly characterized. In situ push-pull methods have been used to identify the fate of NO₃⁻ in the groundwater. In this study, we adapted a previously published in situ denitrification push-pull method to examine the fate of ¹⁵N₂O introduced into the subsoil-groundwater matrix. Enriched ¹⁵N₂O was manufactured, added to groundwater via a closed system in the laboratory, and then introduced into the groundwater-subsoil matrix in an upland-marsh transition zone of a salt marsh and a forested alluvial riparian zone. Conservative tracers (SF₆ and Br⁻) and ¹⁵N₂O were injected into the groundwater and left for 1-4 h after which the groundwater was sampled. Added ¹⁵N₂O behaved in a conservative manner at one site while the other site showed variability with some injections showing significant consumption (3-8 µg N₂O-¹⁵N kg⁻¹ soil d⁻¹) of ¹⁵N₂O. Our results show that the fate and dynamics of N₂O in groundwater are complex and variable and that these dynamics should be considered in the development of improved IPCC inventory calculations.

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