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Description:
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Understanding the role of freshwater wetlands in the global carbon cycle has
become more important as evidence of climate change grows . In this paper , we examine
the burial and decomposition of particulate organic matter (POM ) in a temperate ,
siliciclastic , seasonal wetland . High POM abundances are found in silt layers , while
sand units preserve very little POM . The POM distribution with depth is compared to
the biogeochemistry of sediment porewater with depth . POM acts as a driver for
reduction reactions within the wetland soil . Porewater biogeochemistry and POM
decomposition are controlled by seasonal changes in the level of the water table which
cause seasonal shifts in the oxic /anoxic boundary . At the oxic /anoxic boundary ,
reoxidation of FeS minerals in the soil cause rapid POM decomposition at the average
minimum water table level in the late summer and early fall . Variation in the minimum
depth of the water table from year to year may account for fluctuating POM numbers in
the upper silt layers . The results from this study can be used to predict seasonal water
level fluctuations in ancient wetland and to explain recurrence horizons in peat . |