HR: 0800h
AN: B51D-0246    [Abstracts]
TI: Accuracy and precision in measurements of biomass oxidative ratios
AU: * Gallagher, M E
EM: megirish@rice.edu
AF: Department of Earth Science, Rice University, 6100 Main St, ms 126, Houston, TX 77005 United States
AU: Masiello, C A
EM: masiello@rice.edu
AF: Department of Earth Science, Rice University, 6100 Main St, ms 126, Houston, TX 77005 United States
AU: Randerson, J T
EM: jranders@uci.edu
AF: Department of Earth System Science, UC Irvine, zot code 3100, Irvine, CA 92697 United States
AU: Chadwick, O A
EM: oac@geog.ucsb.edu
AF: Department of Geography, UC Santa Barbara, Girvetz 2308, Santa Barbara, CA 93106-4060 United States
AB: One fundamental property of the Earth system is the oxidative ratio (OR) of the terrestrial biosphere, or the mols CO₂ fixed per mols O₂ released via photosynthesis. This is also an essential, poorly constrained parameter in the calculation of the size of the terrestrial and oceanic carbon sinks via atmospheric O₂ and CO₂ measurements. We are pursuing a number of techniques to accurately measure natural variations in above- and below-ground OR. For aboveground biomass, OR can be calculated directly from percent C, H, N, and O data measured via elemental analysis; however, the precision of this technique is a function of 4 measurements, resulting in increased data variability. It is also possible to measure OR via bomb calorimetry and percent C, using relationships between the heat of combustion of a sample and its OR. These measurements hold the potential for generation of more precise data, as error depends only on 2 measurements instead of 4. We present data comparing these two OR measurement techniques.
DE: 0428 Carbon cycling (4806)
DE: 1055 Organic and biogenic geochemistry
DE: 1615 Biogeochemical cycles, processes, and modeling (0412, 0414, 0793, 4805, 4912)
DE: 1631 Land/atmosphere interactions (1218, 1843, 3322)
SC: Biogeosciences [B]
MN: Fall Meeting 2005