Church, M. R.. U.S. EPA, church@mail.cor.epa.gov
Van Sickle, J. R.. U.S. EPA, johnv@mail.cor.epa.gov

 
REGIONAL-SCALE MODELING OF POTENTIAL FUTURE EFFECTS OF ACIDIC DEPOSITION ON SURFACE WATER CHEMISTRY
 
To estimate the potential future effects of acidic deposition on surface water chemistry in the eastern United States, we modeled the response of 95 predominantly forested small catchments selected to statistically represent several thousand members (watersheds) of a specified (low alkalinity) target population. We used the MAGIC model to project the effects of sulfur deposition on the watersheds and surface waters of interest. We modified the model to estimate the possible relative regional-scale effects of nitrogen deposition through a bounding exercise in which we simulated the effects of decreasing watershed retention of atmospherically deposited nitrogen, and thus increasing leaching of nitrate to surface waters, over 50 years, 100 years and 250 years. We also simulated the effects of continuing retention of atmospheric nitrogen at current rates. Results from this modeling indicate that the potential relative effects of sulfur vs. nitrogen deposition on the alkalinities of eastern surface waters is highly dependent on the time rates of change of watershed retention of deposited nitrogen. In some instances, the projected future effects of nitrogen deposition equaled or exceeded those of sulfur deposition.
 
Day: Wednesday, Feb. 3
Time: Poster
Location: Sweeney Center
 
Code: SS50WE1544S