title: Estimates of critical acid loads and exceedances for forest soils across the conterminous United States.
abstract: Concern regarding the impacts of continued nitrogen and sulfur deposition on ecosystem health has prompted the development of critical acid load assessments for forest soils. A critical acid load is a quantitative estimate of exposure to one or more pollutants at or above which harmful acidification-related effects on sensitive elements of the environment occur. A pollutant load in excess of a critical acid load is termed exceedance. This study combined a simple mass balance equation with national-scale databases to estimate critical acid load and exceedance for forest soils at a 1-km(2) spatial resolution across the conterminous US. This study estimated that about 15% of US forest soils are in exceedance of their critical acid load by more than 250eqha(-1)yr(-1), including much of New England and West Virginia. Very few areas of exceedance were predicted in the western US.
authors.affiliation: USDA Forest Service, Southern Global Change Program, 920 Main Campus Drive, Suite 300, Raleigh, NC 27606, USA. steve_mcnulty@ncsu.edu
authors.forename: Steven G
authors.initials: SG
authors.lastname: McNulty
authors.forename: Erika C
authors.initials: EC
authors.lastname: Cohen
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Moore Myers
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Sullivan
authors.forename: Harbin
authors.initials: H
authors.lastname: Li
mesh_terms: D015258:Acid Rain; D000143:Acids / Q000032:analysis*; D000327:Adsorption; D016208:Databases, Factual; D004463:Ecology / Q000379:methods / Q000706:statistics & numerical data*; D004784:Environmental Monitoring / Q000379:methods*; D004785:Environmental Pollutants / Q000032:analysis*; D006801:Humans; D009584:Nitrogen / Q000032:analysis; D012987:Soil / Q000032:analysis; D012989:Soil Pollutants / Q000032:analysis; D013455:Sulfur / Q000032:analysis; D014197:Trees; D014481:United States
chemical_list: D015258:Acid Rain; D000143:Acids; D004785:Environmental Pollutants; D012987:Soil; D012989:Soil Pollutants; D013455:Sulfur; D009584:Nitrogen