Critical Loads of Sulfur and Nitrogen and Modeled Effects of Deposition Reduction for Forested Ecosystems of Great Smoky Mountains National Park
Pardo LH, Duarte N, Van Miegroet H, Fisher LS, Robin-Abbott MJ. 2018. Critical Loads of Sulfur and Nitrogen and Modeled Effects of Deposition Reduction for Forested Ecosystems of Great Smoky Mountains National Park. General Technical Report NRS-180. Northern Research Station, National Forest Service, United States Department of Agriculture. Newtown Square, Pennsylvania
CONCLUSIONS (in part): By calculating critical loads and exceedances for four sites within the GSMNP and using different critical thresholds, we were able to evaluate which threshold is most likely to provide accurate results. The Al:Bc = 0.1 mol mol-1 and no decrease in base saturation gave the most accurate assessment of the critical load based on long-term observation of site conditions. In spite of decreases in S emissions and deposition over the last few decades, recovery of these ecosystems would require very stringent reductions in deposition. The N deposition reductions necessary to lower deposition below the critical load for nutrient N range from 68 percent to 90 percent of total N deposition; reductions required to lower total (N + S) deposition below the critical load range from 14 percent to 53 percent. These reductions would not, however, lower soil solution concentrations to below the critical thresholds before 2150. The CAIR (U.S. EPA, n.d.) deposition reduction scenario represents reductions of only approximately 40 percent of N + S and would therefore not be adequate to reduce deposition below the critical load at the most sensitive site. Continued emissions reductions associated with attaining National Ambient Air Quality Standards or visibility improvements in federally mandated class 1 areas may eliminate exceedance of critical loads at GSMNP.
- Type
- Published Report
- Authors
- Pardo, Linda; Duarte, Natasha; Van Miegroet, Helga; Fisher, L; Robin-Abbott, Molly
- Date of Issue
- 2018-09
- Publisher
- Northern Research Station, National Forest Service, United States Department of Agriculture
- Units
- GRSM
- Keywords
- acidification, air quality, APHN, Appalachian Highlands Network, critical loads, deposition, Great Smoky Mountains National Park, GRSM, GRSM-00762, nitrogen, SER, soils, Southeast Region, sulfur, vital signs