Peatland stream lipid biogeochemistry features in an intermediate Fen Peatland, Ontario Canada

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Department of Biological Sciences


Changes in climate and land use pressures in the boreal region may influence peatland stream sediment organic carbon (C) dynamics. Fifteen to 50% of stream sediment organic C resides in recalcitrant pools, with the lipids accounting for up to 25% of the peatland C pool. Nevertheless, lipid mineralization within peatlands and their draining stream sediments is poorly understood. Potential esterase activity, which is known to be an important enzyme group in recalcitrant C decomposition, is presented as an indicator of lipid hydrolysis in three streams surrounding an intermediate fen peatland. Organic C concentration ranged from 5 to 250 g C kg-1 sediment during the sampling period, with the recalcitrant C pool accounting for 15 to 20%. Fourier Transform Infrared (FTIR) spectra were typical of humic-like substances, such as aliphatic compounds (including lipids), phenolic and other aromatic structures, carboxyl groups, and polysaccharide structures. Esterase activity was positively correlated with organic C and total nitrogen (N) concentrations, and sediment pH. Esterase was most active in the presence of high organic C fractions and recalcitrant C, supporting the hypothesis that lipid hydrolysis in the peatland stream sediments may be an important and underestimated component of peatland C sequestration dynamics.

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