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MODELING THE HYDROGEOCHEMICAL RESPONSE OF A STREAM TO ACID DEPOSITION USING THE ENHANCED TRICKLE-DOWN MODEL
Citation:
Nikolaidis, N., P. Muller, J. Schnoor, AND H. Hu. MODELING THE HYDROGEOCHEMICAL RESPONSE OF A STREAM TO ACID DEPOSITION USING THE ENHANCED TRICKLE-DOWN MODEL. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-93/204.
Description:
The enhanced trickle-down model was applied to White Oak Run, a second-order stream, located in the Shenandoah National Park, Virginia, on the western slope of the Blue Ridge Mountains. alibration of the model was performed using five years of field data collected at the site. imulation results indicated that 30% of the incoming sulfate is being retained in the upper soil horizons and 15% is being retained in the unsaturated zone compartment. he alkalinity concentrations in the stream exhibited a seasonal variation with increased values during low flow and decreased values during high flow. on exchange processes in the upper soil neutralized 5OW of the incoming acidity and weathering processes accounted for 20t of the neutralization in the unsaturated zone. ong term (100 year duration) simulations indicated the White Oak Run is a delayed response system primarily due to high sulfate sorption capacity. ulfate desorbed from the soils after 40-50 years, assuming no reductions in the current deposition. his has significant policy implications because reductions in deposition levels will not result in a quick recovery of the system.