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Title: Denitrification in bottomland hardwood soils of the Cache River, Arkansas
Authors: Louisiana State University (Baton Rouge, La.). Wetland Biogeochemistry Institute.
Wetlands Research Program (U.S.)
Boar, Rosalind R.
DeLaune, R. D.
Lindau, C. W.
Patrick, W. H. (William H.), 1925-
Keywords: Bottomland hardwoods
Nitrogen cycling
Water quality
Cache River
Floodplain forests
Wetland ecology
Publisher: Environmental Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Description: Technical Report
Abstract: To give initial nitrate-N concentrations of about 9 mg L⁻¹, ¹⁵N labeled nitrate was added to sediment-water columns containing wetland sediment and river water. Over 40 days, nitrate-N in floodwater decreased by between 82 and 59 percent, which gave estimates of N export from the water column of 11.5 mg N m⁻² day⁻¹ and 7.5 mg N m⁻² day⁻¹. These values are low compared with wetland systems elsewhere and correlated directly with the organic content of surface sediment, which included the forest litter. Added glucose at least doubled rates of nitrate loss, which were then presumed to have been carbon limited. Nitrification was estimated using changes in atom percent ¹⁵N₃ alone and not changes in atom percent NH₄, which is a more usual method. Contributions of NO₃ to water from nitrification were small related to initial organic contents and were estimated at between 5 and 12 percent of the amounts by which nitrate reduced. Rates of nitrogen transfonnation in these forested swamps are likely to be set by rate of supply of soluble carbon from tree litter and perhaps canopy leachate, rather than by nitrate concentration in inflowing floodwater.
Appears in Collections:Technical Report

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