HR: 1400h
AN: B13A-04    [Abstracts]
TI: Hydrogen coupled CO2 fixation in legume cropping systems
AU: * Philpott, T
EM: 4tp4@queensu.ca
AF: Department of Geography, Queen's University, Kingston, Ontario K7L 3N6, Kingston, ON K7L 3N6, Canada
AU: Cen, Y
EM: yc3@queensu.ca
AF: Department of Geography, Queen's University, Kingston, Ontario K7L 3N6, Kingston, ON K7L 3N6, Canada
AU: Layzell, D B
EM: dlayzell@ucalgary.ca
AF: ISEE, University of Calgary, Calgary, Alberta T2N 1N4, Canada
AU: Kyser, K
EM: kyser@geol.queensu.ca
AF: Department of Geology, Queen's University, Kingston, Ontario K7L 3N6, Canada
AU: Scott, N A
EM: scottn@queensu.ca
AF: Department of Geography, Queen's University, Kingston, Ontario K7L 3N6, Kingston, ON K7L 3N6, Canada
AB: Electron flow from oxidation of excess H2 released by root nodules was shown to contribute to microbial CO2 fixation in soybean crops. This discovery has important implications for carbon storage in soils used to grow legumes; however, further research is needed to understand the fate and turnover time of this H2-coupled CO2 fixation. Isotopic labeling of soil through incubation with 13CO2 was used to elucidate movement of sequestered carbon into soil carbon pools. Measurement of isotopic shifts was determined using Isotope Ratio Mass Spectrometry. Preliminary experiments have confirmed CO2 uptake through an isotopic shift (Δ¹³C -20.4 to -14.5 ‰) in 24 hour incubated soils labeled with 13CO2 (1% v/v, 99.5 Atom%) under elevated H2 concentration (6000 ppm). Other incubation experiments have confirmed the biotic nature of observed CO2 uptake by comparing isotopic shifts in oven dried and autoclaved soils to moist soil. Under an elevated H2 atmosphere, no significant isotopic shift was observed in dry and autoclaved soils whereas moist soil showed an isotopic shift of Δ¹³C -21.9 to 11.4 ‰ over 48 hours. Future experiments will involve longer incubations (7 days) and will be aimed at determining isotopic shifts within soil carbon pools. Samples will be incubated and fractionated into microbial biomass, light fraction carbon, and acid stable carbon and subsequent isotopic analysis will be carried out. This will help determine the distribution of H2- coupled fixed CO2 within soil carbon pools and the turnover time of sequestered carbon. This and further research may lead to modification of greenhouse gas coefficients for leguminous crops that includes a CO2 fixation component.
DE: 0400 BIOGEOSCIENCES
DE: 0402 Agricultural systems
DE: 0428 Carbon cycling (4806)
SC: Biogeosciences [B]
MN: 2009 Joint Assembly