Nitrate Removal in a Riparian Wetland of the Appalachian Valley and Ridge Physiographic Province
- Oscar P. Flitea,
- Robert D. Shannon *b,
- Ronald R. Schnabelc and
- Richard R. Parizekd
- a III, Environmental Pollution Control Program, 249 Agricultural Engineering Bldg., The Pennsylvania State University, University Park, PA 16802
b Dep. of Agricultural and Biological Engineering, 233 Agricultural Engineering Bldg., The Pennsylvania State University, University Park, PA 16802
c Pasture Systems & Watershed Management Research Lab, USDA-ARS, Building 3702, Curtin Road, University Park, PA 16802
d Department of Geosciences, 304 Deike Bldg., The Pennsylvania State University, University Park, PA 16802
Riparian zones within the Appalachian Valley and Ridge physiographic province are often characterized by localized variability in soil moisture and organic carbon content, as well as variability in the distribution of soils formed from alluvial and colluvial processes. These sources of variability may significantly influence denitrification rates. This investigation studied the attenuation of nitrate (NO− 3–N) as wastewater effluent flowed through the shallow ground water of a forested headwater riparian zone within the Appalachian Valley and Ridge physiographic province. Ground water flow and NO− 3–N measurements indicated that NO− 3–N discharged to the riparian zone preferentially flowed through the A and B horizons of depressional wetlands located in relic meander scars, with NO− 3–N decreasing from >12 to <0.5 mg L−1 Denitrification enzyme activity (DEA) attributable to riparian zone location, soil horizon, and NO− 3–N amendments was also determined. Mean DEA in saturated soils attained values as high as 210 μg N kg−1 h−1, and was significantly higher than in unsaturated soils, regardless of horizon (p < 0.001). Denitrification enzyme activity in the shallow A horizon of wetland soils was significantly higher (p < 0.001) than in deeper soils. Significant stimulation of DEA (p = 0.027) by NO− 3–N amendments occurred only in the meander scar soils receiving low NO− 3–N (<3.6 mg L−1) concentrations. Significant denitrification of high NO− 3–N ground water can occur in riparian wetland soils, but DEA is dependent upon localized differences in the degree of soil saturation and organic carbon content.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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