HR: 0800h
AN: B21A-0847    [Abstracts]
TI: The Isotopomer Signal of N$_{2}$O Produced From Biological Sources
AU: * Parkes, S D
EM: sdp05@uow.edu.au
AF: University of Wollongong, Northfields Ave, Wollongong, NSW 2522 Australia
AU: Griffith, D W
EM: griffith@uow.edu.au
AF: University of Wollongong, Northfields Ave, Wollongong, NSW 2522 Australia
AU: Wilson, S R
EM: swilson@uow.edu.au
AF: University of Wollongong, Northfields Ave, Wollongong, NSW 2522 Australia
AU: Chen, D
EM: delichen@unimelb.edu.au
AF: The University of Wollongong, Grattan Street, Parkville, VIC 3052 Australia
AU: Mills, A R
EM: arm00@uow.edu.au
AF: University of Wollongong, Northfields Ave, Wollongong, NSW 2522 Australia
AU: Turner, D
EM: d.turner@pgrad.unimelb.edu.au
AF: The University of Wollongong, Grattan Street, Parkville, VIC 3052 Australia
AB: Atmospheric concentrations of N$_{2}$O have increased significantly since the industrial revolution; this is predominantly the result of the increasing nitrogen inputs to the biosphere. Although this is accepted as the major source of increasing atmospheric N$_{2}$O, the uncertainty associated with the quantification of these emissions is quite large. This uncertainty is partly because of both the poor understanding of the biological mechanisms producing N$_{2}$O, and their relative contributions to N$_{2}$O emissions. Isotopic fractionation provides insight into the processes responsible for N$_{2}$O emissions. Here we present measurements of the isotopic composition of N$_{2}$O emitted from different sources. To provide an improved signal for the minor isotopomers (specifically $^{15}$N$^{14}$N$^{16}$O and $^{14}$N$^{15}$N$^{16}$O), some of the analysis sites were fertilised with substrate that was 10% $^{15}$N enriched, providing a 20 fold increase in the signal for the minor isotopes. Collection of samples involved the cryogenic trapping of N$_{2}$O collected from the headspace of chambers over soil plots or estuarine sediments. The samples were analysed in the laboratory using high resolution FTIR spectrometry. The isotopomer measurements were augmented with soil parameters such as, nitrate and ammonium concentration, water filled pore space (WFPS) and pH. The combined measurements provide insight into the likely N$_{2}$O production mechanisms.
DE: 1610 Atmosphere (0315, 0325)
DE: 1615 Biogeochemical processes (4805)
DE: 0315 Biosphere/atmosphere interactions
DE: 0400 Biogeosciences
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting