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Importance of the Water Table in Controlling Dissolved Carbon along a Fen Nutrient Gradient
Author(s) -
Webster Kara L.,
McLaughlin James W.
Publication year - 2010
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2009.0111
Subject(s) - dissolved organic carbon , peat , alkalinity , water table , nutrient , environmental science , environmental chemistry , hydrology (agriculture) , chemistry , ecology , groundwater , geology , biology , geotechnical engineering , organic chemistry
Boreal fens are minerotrophic peatlands that act as important control points for dissolved C between upland and aquatic ecosystems. Fens occupy a minerotrophic continuum from “rich,” having high water tables and large nutrient contributions from upland sources, to “poor,” having low water tables and small nutrient contributions. Dissolved C within these fens will be influenced by the degree of minerotrophy, which in turn impacts peat pore water acidity and alkalinity and downstream productivity. To examine how dissolved C concentrations change along the minerotrophic gradient and to explore possible mechanisms controlling their concentration, pore water chemistry was analyzed from piezometers at 25‐, 50‐, and 100‐cm depths in rich, intermediate, and poor fens during the snow‐free periods of 2005, 2006 (dissolved organic C [DOC] only), 2007, and 2008. We found that dissolved inorganic C (DIC) concentrations increased with higher water tables (poor < intermediate < rich) and wetter years (2005 < 2007 ∼ 2008). In contrast, DOC concentrations decreased with higher water tables (rich < intermediate < poor), but the effect differed among years. Wetter conditions resulted in high DOC concentrations in the intermediate fen, low concentration in the poor fen, and no change in the rich fen. Correlation analyses suggest that DIC concentrations may be linked to groundwater contribution of carbonate materials and DOC to ionic strength and mechanisms of productivity and decomposition. Although further experimentation is required to verify these mechanisms, the evidence points to the importance of minerotrophic status when considering the role of peatlands in watershed C balances and their response to changing climate.