Spatial Decision Support for Assessing Impacts of Atmospheric Sulfur Deposition on Aquatic Ecosystems in the Southern Appalachian Region

We present foundational work on the use of niche modeling to predict continuous surfaces of acid neutralizing capacity (ANC) and base cation weathering (BCw) within the southern Appalachian Mountain Region of the United States. Predicted ANC and BCw surfaces are subsequently used to estimate steady-state critical loads (CLs) of atmospheric sulfur deposition. We then present a logic-based model for assessing aquatic environmental effects of sulfur deposition throughout the region based on modeled stream ANC and CL exceedance, and demonstrate application of the logic model in a spatial decision-support system, presenting mapped model results for Great Smoky Mountain National Park. Whereas CLs were uniformly high within the Park area, degree of aquatic impact within watersheds was strongly associated with increasing elevation. The niche and spatial decision support modeling approaches are readily customized for other regions of interest.