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We report the results of an investigation on the processes controlling heat transport in peat under a large bog in the Glacial Lake Agassiz Peatlands. For 2 years, starting in July 1998, we recorded temperature at 12 depth intervals from 0 to 400 cm within a vertical peat profile at the crest of the bog at sub-daily intervals. We also recorded air temperature 1 m above the peat surface. We calculate a peat thermal conductivity of 0.5 W m -1 °C-1 and model vertical heat transport through the peat using the SUTRA model. The model was calibrated to the first year of data, and then evaluated against the second year of collected heat data. The model results suggest that advective pore-water flow is not necessary to transport heat within the peat profile and most of the heat is transferred by thermal conduction alone in these waterlogged soils. In the spring season, a zero-curtain effect controls the transport of heat through shallow depths of the peat. Changes in local climate and the resulting changes in thermal transport still may cause non-linear feedbacks in methane emissions related to the generation of methane deeper within the peat profile as regional temperatures increase. [ABSTRACT FROM AUTHOR]

(1) A topographic survey was conducted with both laser and electronic levels across a spring fen, a raised bog and the water track (fen) between them, in the Lost River Peatland of northern Minnesota. (2) The survey demonstrated that the spring fen consisted of a peat mound whose slopes were steeper than that of the bog. (3) Three successive surveys in 1982 and 1983 showed altitudinal changes in benchmarks fixed in trees relative to a base level on a power-line pylon located in the water track. Nearly all benchmarks rose, with the greatest rises occurring near the centres of the raised bog (11 cm) and spring fen (6 cm) in contrast to very slight rises across the water track. (4) The most likely explanation for this altitudinal change is a swelling of the sub surface peat in response to artesian fluid pressure generated by regional hydraulic gradients. (5) Very precise determinations of altitude are thus possible with a laser or electronic level on an unstable peat substrate, providing great care is taken in surveying techniques. [ABSTRACT FROM AUTHOR]

Abstract: Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR-MS) was used to identify the qualitative differences between dissolved organic matter (DOM) in fen and bog porewaters from the Red Lake II system in the Glacial Lake Agassiz Peatlands (GLAP) of northern Minnesota. Approximately 80% of the molecular composition in surface porewater was maintained throughout the upper portion of the bog profile (0.17–2.50m). The qualitative stability of the composition of the DOM was accompanied by a quantitative increase in dissolved organic carbon (DOC) with depth. The composition of DOM in the fen was significantly different at depth, with slightly varying DOC levels. Aromaticity index (AI) values were used to identify condensed aromatic and phenol-type compounds in the porewater of both peatlands. Surface bog and deep fen DOM had surprisingly similar molecular composition. Differences in enzymatic degradation rates via phenol oxidase in the bog and surface fen horizons, slower transport down the bog vertical profile and the presence of a stratum of Sphagnum-woody peat at depth in the fen are suggested as being responsible for the observed variations in DOM composition. [Copyright &y& Elsevier]