HR: 0800h
AN: B21A-0850    [Abstracts]
TI: Site-specific N$_{2}$O isotopic compositions from Brazilian Amazon soils and their implications for the global N$_{2}$O isotope budget
AU: * Park, S
EM: sunyoung@uclink4.berkeley.edu
AF: Department of Earth and Planetary Science, University of California, Berkeley, DG26 Giauque Hall, UC Berkeley, Berkeley, CA 94720-4767
AU: Perez, T J
EM: tjperez@uci.edu
AF: Department of Earth System Science, University of California, Irvine, 3232 Croul Hall, UC Irvine, Irvine, CA 92697-3100
AU: Perez, T J
EM: tjperez@uci.edu
AF: Lab. Quimica Atmosferica, IVIC, Aptdo. 21827, Caracas, 1020-A Venezuela
AU: Thompson, A E
EM: alex@nature.berkeley.edu
AF: Division of Ecosystem Sciences, Department of Environmental Science, Policy, and Management, University of California, Berkeley, 151 Hilgard Hall, UC Berkeley, Berkeley, CA 94720-3110
AU: Boering, K A
EM: boering@cchem.berkeley.edu
AF: Department of Earth and Planetary Science, University of California, Berkeley, DG26 Giauque Hall, UC Berkeley, Berkeley, CA 94720-4767
AU: Boering, K A
EM: boering@cchem.berkeley.edu
AF: Department of Chemistry, University of California, Berkeley, BG3 Hildebrand Hall, UC Berkeley, Berkeley, CA 94720-1460
AU: Firestone, M K
EM: mkfstone@nature.berkeley.edu
AF: Division of Ecosystem Sciences, Department of Environmental Science, Policy, and Management, University of California, Berkeley, 151 Hilgard Hall, UC Berkeley, Berkeley, CA 94720-3110
AU: Trumbore, S E
EM: setrumbo@uci.edu
AF: Department of Earth System Science, University of California, Irvine, 3232 Croul Hall, UC Irvine, Irvine, CA 92697-3100
AU: Tyler, S C
EM: styler@uci.edu
AF: Department of Earth System Science, University of California, Irvine, 3232 Croul Hall, UC Irvine, Irvine, CA 92697-3100
AB: The site-specific $^{15}$N signature of N$_{2}$O (i.e., the $^{15}$N isotopic composition at the central or terminal position, expressed as $\delta$$^{15}$N$^{\alpha}$ or $\delta$$^{15}$N$^{\beta}$) from natural sources (e.g., tropical rain forest soils) remains poorly explored, despite indications from the few measurements available that the signature can be used for distinguishing microbiological N$_{2}$O production mechanisms in soils and for reducing uncertainties in the global isotope budget. We present measurements of site-specific $\delta$$^{15}$N$^{\alpha}$, $\delta$$^{15}$N$^{bulk}$ (i.e., the average of the two N atom positions), and $\delta$$^{18}$O of N$_{2}$O of soil gas samples collected in March 2002 during the rainy season in the Tapajos National Forest (TNF), Para, Brazil and on N$_{2}$O emissions from soil incubation experiments using the TNF soils and soils from Nova Vida Farm, Rondonia, Brazil. The microbiological and physical processes that could play roles in the observed distribution and variation of N$_{2}$O isotopologues from the tropical forest soils will be discussed and compared with results for N$_{2}$O produced in laboratory cultures of denitrifying bacteria and with stratospheric N$_{2}$O observations. We then use the combination of data from tropical soils, bacterial cultures and the stratosphere to constrain the contribution of the tropical forest soils to the atmospheric N$_{2}$O isotope budget.
DE: 4870 Stable isotopes
DE: 1615 Biogeochemical processes (4805)
DE: 0315 Biosphere/atmosphere interactions
DE: 0322 Constituent sources and sinks
DE: 0400 Biogeosciences
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting