title: Comparison among model estimates of critical loads of acidic deposition using different sources and scales of input data.
abstract: The critical load (CL) of acidic atmospheric deposition represents the load of acidity deposited from the atmosphere to the earth's surface at which harmful acidification effects on sensitive biological receptors are thought to occur. In this study, the CL for forest soils was estimated for 27 watersheds throughout the United States using a steady-state mass balance approach based on both national and site-specific data and using different approaches for estimating base cation weathering. Results suggested that the scale and source of input data can have large effects on the calculated CL and that the most important parameter in the steady-state model used to estimate CL is base cation weathering. These results suggest that the data and approach used to estimate weathering must be robust if the calculated CL is to be useful for its intended purpose.
authors.affiliation: E&S Environmental Chemistry, Inc., P.O. Box 609, Corvallis, OR 97339, USA. todd.mcdonnell@esenvironmental.com
authors.forename: T C
authors.initials: TC
authors.lastname: McDonnell
authors.forename: B J
authors.initials: BJ
authors.lastname: Cosby
authors.forename: T J
authors.initials: TJ
authors.lastname: Sullivan
authors.forename: S G
authors.initials: SG
authors.lastname: McNulty
authors.forename: E C
authors.initials: EC
authors.lastname: Cohen
mesh_terms: D015258:Acid Rain / Q000032:analysis / Q000706:statistics & numerical data; D001272:Atmosphere / Q000737:chemistry; D004787:Environmental Pollution / Q000032:analysis / Q000706:statistics & numerical data*; D008956:Models, Chemical; D009566:Nitrates / Q000032:analysis*; D009584:Nitrogen / Q000032:analysis; D012989:Soil Pollutants / Q000032:analysis; D013431:Sulfates / Q000032:analysis*; D013455:Sulfur / Q000032:analysis
chemical_list: D015258:Acid Rain; D009566:Nitrates; D012989:Soil Pollutants; D013431:Sulfates; D013455:Sulfur; D009584:Nitrogen