HR: 11:35h
AN: B52C-06    [Abstracts]
TI: Geophysical monitoring of biogenic gas dynamics in a northern peatland: seasonal variability and implications for production rates
AU: * Comas, X
EM: xcomas@fau.edu
AF: Florida Atlantic University, Dept. of Geosciences 777 Glades Rd., Boca Raton, FL 33431, United States
AU: Slater, L
EM: lslater@andromeda.rutgers.edu
AF: Rutgers University, Dept. of Earth and Environmental Sciences, Newark, NJ 07102, United States
AU: Reeve, A
EM: asreeve@maine.edu
AF: University of Maine, Dept. of Earth Sciences, Orono, ME 04469, United States
AU: Nolan, J
EM: jtnolan@pegasus.rutgers.edu
AF: Rutgers University, Dept. of Earth and Environmental Sciences, Newark, NJ 07102, United States
AB: In-situ biogenic gas dynamics and seasonal variability within a northern peatland in Maine (Caribou Bog) were investigated using a set of high resolution surface ground penetrating radar (GPR) surveys. Measurements were combined with elevation rod (to monitor surface deformation) and gas flux measurements. Spatial variability in gas production was also investigated by comparing two sites with different geological and ecological attributes, and showed a striking dependence on seasonal variability. One site characterized by thick highly humified peat deposits (5-6 m), wooded heath vegetation and open pools showed large ebullition events during the summer season, emitting up to 156 g CH₄ m^-2 during a single event. The other site characterized by thinner less humified peat deposits (2-3 m) and shrub vegetation showed much smaller ebullition events during the same season (accounting for up to 21 g CH₄ m^-2). A period of biogenic gas accumulation during the fall and winter (as enhanced by the frozen surficial peat acting as a confining layer) was followed by a large FPG release after the snow/ice melt that released approximately 180 g CH₄ m^-2 from both sites. Gas production rates were directly estimated from the time series of GPR measurements (ranging between 0.35-1.80 g CH₄ m^-3 d^-1 during periods of biogenic gas accumulation) and reflected strong seasonal and spatial variability. Periods of decreased atmospheric pressure showed certain correspondence with short-period increases in biogenic gas flux (including a very rapid decrease in FPG content associated with an ebullition event that released an estimated 61 g CH₄ m^-2 in less than 3.5 hours). These results provide insights into the spatial and seasonal variability in production and emission of biogenic gases from northern peatlands
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0428 Carbon cycling (4806)
DE: 0994 Instruments and techniques
DE: 1810 Debris flow and landslides
SC: Biogeosciences [B]
MN: 2007 Fall Meeting