HR: 08:45h
AN: B41G-04    [Abstracts]
TI: Quantification of nitrous oxide emissions from nitrification and denitrification based on intramolecular site preference measurements
AU: * Parkes, S D
EM: sdp05@uow.edu.au
AF: Centre for Atmospheric Chemistry, Dept. of Chemistry, University of Wollongong, Wollongong, NSW 2522, Australia
AU: Wilson, S R
EM: swilson@uow.edu.au
AF: Centre for Atmospheric Chemistry, Dept. of Chemistry, University of Wollongong, Wollongong, NSW 2522, Australia
AU: Griffith, D W
EM: griffith@uow.edu.au
AF: Centre for Atmospheric Chemistry, Dept. of Chemistry, University of Wollongong, Wollongong, NSW 2522, Australia
AU: Chen, D
EM: delichen@unimelb.edu.au
AF: Faculty of Land and Food Resources, School of Resource Management, University of Melbourne, Melbourne, Vic 3010, Australia
AB: The intramolecular site preference of N₂O was measured during a 2 week field campaign at a dairy farm in south eastern Australia. Field chambers were treated with ¹⁵N labelled ammonium or nitrate, either at application rates of 100 or 50 kg-N.ha^-1, followed by irrigation. N2O emissions, ¹⁵N composition of N₂O, soil mineral nitrogen concentrations and ¹⁵N composition, as well as soil moisture were monitored. From the interpretation of the collected data, site preference signatures were assigned to nitrification and denitrification. The calculated site preference signatures for nitrification and denitrification were -28 (±8) and 7 (±3) ‰ respectively. The assigned site preference signatures were used to determine the contribution of nitrification and denitrification to the emitted N₂O. For all treatments denitrification sourced N₂O emissions far outweighed (>90%) nitrification. N₂O emission factors (amount of N emitted as N₂O per amount of N applied) were also calculated for nitrification and denitrification from each treatment. This study illustrates the capacity of site preference measurements to quantify the relative contributions of nitrification and denitrification in field studies.
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0454 Isotopic composition and chemistry (1041, 4870)
DE: 0469 Nitrogen cycling
DE: 0470 Nutrients and nutrient cycling (4845, 4850)
DE: 0490 Trace gases
SC: Biogeosciences [B]
MN: 2007 Fall Meeting