HR: 0830h
AN: B31E-0349    [PDF]
TI: Description and Preliminary Results From an On-Line Method of Analysis of $\delta^{13}$C and $\delta^{18}$O of CO$_{2}$
AU: * Pierce, D L
EM: dlpierce@ucdavis.edu
AF: Biosphere 2 Center, 32540 S. Biosphere Rd., Oracle, AZ 85623 United States
AU: Bissell, S
EM: sbissell@bio2.edu
AF: Biosphere 2 Center, 32540 S. Biosphere Rd., Oracle, AZ 85623 United States
AU: Giles, L
EM: lgiles@globalecology.stanford.edu
AF: Carnegie Institute of Washington, Department of Plant Biology 260 Panama St., Stanford, CA 94305 United States
AU: Wright, A
EM: awright@bio2.edu
AF: Biosphere 2 Center, 32540 S. Biosphere Rd., Oracle, AZ 85623 United States
AU: van Haren, J
EM: jvanhare@bio2.edu
AF: Biosphere 2 Center, 32540 S. Biosphere Rd., Oracle, AZ 85623 United States
AU: Yakir, D
EM: dan.yakir@weizmann.ac.il
AF: Weizmann Institute of Science, Department of Environmental Sciences and Energy Research, Rehovot, 76100 Israel
AU: Berry, J A
EM: joeberry@globalecology.stanford.edu
AF: Carnegie Institute of Washington, Department of Plant Biology 260 Panama St., Stanford, CA 94305 United States
AU: Lin, G
EM: glin@bio2.edu
AF: Biosphere 2 Center, 32540 S. Biosphere Rd., Oracle, AZ 85623 United States
AB: At the Biosphere 2 Center in Oracle, Arizona we have developed a continuous flow analysis method to measure in "real-time" the concentration, $^{13}$C/$^{12}$C, and $^{18}$O/$^{16}$O of CO$_{2}$ in air. CO$_{2}$ isotope analysis in air samples is crucial for the partitions of the net ecosystem flux into its net assimilation and respiration components. Previous analysis techniques depend on having many glass flasks and transporting the flask samples to the lab for analysis. Our technique transports gas using 1/4 inch tubing from various sampling points in Biosphere 2 Center to an on-site laboratory, which houses the on-line discrimination stable isotope mass spectrometer (O.L.D.S.I.M.S.). OLDSIMS is a system designed to combine a Licor 6262 gas analyzer (Lincoln, NE) for instant CO$_{2}$ concentration values, a SIRA (Stable Isotope Ratio Analyzer, VG-Micromass, UK), and a Process Control computer for peripheral system control and coordination with the SIRA. The stable isotope and concentration analysis of one sample as well as a know reference gas currently takes OLDSIMS 12.4 minutes to run. Results from a diurnal run of a standard CO$_{2}$ tank are: [CO$_{2}$] = 998.7 $\pm$ 0.45 ppm, $\delta^{13}$C = -3.34 $\pm$ 0.098 $\permil$, $\delta^{18}$O = -11.75 $\pm$ 0.108 $\permil$ vs PDB. During our presentation we will show this and other data collected at the Biosphere 2 Center tropical rainforest biome to demonstrate the capabilities of this "real-time" technique.
DE: 0315 Biosphere/atmosphere interactions
DE: 1694 Instruments and techniques
SC: Biogeosciences [B]
MN: 2003 Fall Meeting