HR: 16:15h
AN: NB14B-04    [Abstracts]
TI: Carbon Dioxide and Methane Emissions from Streams in the Boreal Forest of Interior Alaska
AU: * Jones, J B
EM: ffjbj@uaf.edu
AF: University of Alaska Fairbanks, Institute of Arctic Biology, Fairbanks, AK 99775 United States
AU: Betts, E F
EM: ftefb@uaf.edu
AF: University of Alaska Fairbanks, Institute of Arctic Biology, Fairbanks, AK 99775 United States
AB: The boreal forest accounts for only 8% of the land surface yet stores nearly 40% of the world's reactive soil carbon. Much of the boreal forest is underlain with discontinuous permafrost, which is actively degrading with climatic warming. As permafrost thaws, soil organic matter is exposed and potentially degraded by microorganisms. Using measurements of carbon dioxide and methane concentrations in stream water, in conjunction with experimental injections of conservative solute and volatile gas tracers, we examined CO₂ and CH₄ emissions from streams of varying size in interior Alaska. Both CO₂ and CH₄ were supersaturated with average partial pressures in headwater streams ranging from 10 - 24 ppmv for CH₄ and 680 - 1043 ppmv for CO₂. In mid-order streams, the partial pressure of CH4 was higher ranging from 44 - 85 ppmv, but CO₂ was not elevated relative (573 - 675 ppmv) to headwaters. However, in thermokarst streams, which form due to rapid degradation of permafrost, both gases were greatly elevated with partial pressures from 1140 - 4519 ppmv for CO₂ and 985 - 3400 ppmv for CH₄. These results suggest that as soil organic matter is liberated by permafrost degradation, a sizeable proportion of carbon will be lost to the atmosphere as methane.
DE: 0400 Biogeosciences
DE: 1615 Biogeochemical processes (4805)
DE: 1871 Surface water quality
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly