The Isotopomer Signal of N2O Produced From Biological Sources
Abstract
Atmospheric concentrations of N2O 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 N2O, 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 N2O, and their relative contributions to N2O emissions. Isotopic fractionation provides insight into the processes responsible for N2O emissions. Here we present measurements of the isotopic composition of N2O emitted from different sources. To provide an improved signal for the minor isotopomers (specifically 15N14N16O and 14N15N16O), some of the analysis sites were fertilised with substrate that was 10% 15N enriched, providing a 20 fold increase in the signal for the minor isotopes. Collection of samples involved the cryogenic trapping of N2O 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 N2O production mechanisms.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2004
- Bibcode:
- 2004AGUFM.B21A0847P
- Keywords:
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- 1610 Atmosphere (0315;
- 0325);
- 1615 Biogeochemical processes (4805);
- 0315 Biosphere/atmosphere interactions;
- 0400 Biogeosciences