SS3.04 Biogeochemistry of DOC/DON in a Watershed Context
Date: Wednesday, June 12, 2002
Location: Poster Session - VCC
 
FernandesPR, University of South Carolina Sumter, Sumter, USA, pefernan@uscsumter.edu
Bishoff, S, T, University of South Carolina Sumter, Sumter, USA, steveb@uscsumter.edu
Castleberry, J, T, University of South Carolina Sumter, Sumter, USA, joshuacastleberry@hotmail.com
Morris, J, T, University of South Carolina, Columbia, USA, morris@sc.edu
 
NITROGEN AND PHOSPHORUS REMOVAL EFFICIENCY OF NATURAL FRESHWATER WETLANDS RECEIVING TREATED WASTEWATER
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The nutrient removal efficiency of natural freshwater wetlands was investigated in a South Carolina river receiving about 45 Ml/d of secondarily treated sewage effluent. Spatial and temporal trends in nutrients in porewater and surface water were investigated. Concentrations of NH4 and PO4 in effluent averaged 4.7 and 82.6 umol/l, respectively. Surface water nutrient concentrations upstream and just below the point of effluent discharge were 0.8 and 2.1 umol/l of NH4 and 0.7 and 6.3 umol/l of PO4, respectively. At a distance 5.6 km downstream, NH4 had declined to 1.6 umol/l, while PO4 had increased to 16.1 umol/l. The N:P ratio declined from 1.7 upstream to 0.1 at the furthest point downstream. Porewater nutrients declined exponentially with depth, except at the farthest station downstream where PO4 concentrations at 10 and 25 cm were significantly greater than at 50 cm. Wetlands below the point of effluent discharge appear to be saturated with PO4. Thus, while the nitrogen removal efficiency of these wetlands remains high, the capacity of wetlands to remove phosphorus is probably limited by the sorption capacity of sediment.