Grantee Research Project Results
Final Report: Regional scale impacts of Phases I and II of the Clean Air Act Amendments of 1990: The relationship between changes in emissions of SO2 and NOx, and wet and dry deposition of hydrogen ion, and sulfur and nitrogen compounds
EPA Grant Number: R826760Title: Regional scale impacts of Phases I and II of the Clean Air Act Amendments of 1990: The relationship between changes in emissions of SO2 and NOx, and wet and dry deposition of hydrogen ion, and sulfur and nitrogen compounds
Investigators: Likens, Gene E. , Butler, Thomas J.
Institution: Cary Institute of Ecosystem Studies
EPA Project Officer: Chung, Serena
Project Period: September 21, 1998 through September 20, 2001
Project Amount: $172,860
RFA: Regional Scale Analysis and Assessment (1998) RFA Text | Recipients Lists
Research Category: Aquatic Ecosystems , Ecological Indicators/Assessment/Restoration
Objective:
The objective of this research project was to assess the impact of the Clean Air Act Amendments of 1990 on precipitation and air chemistry for the eastern United States.
Summary/Accomplishments (Outputs/Outcomes):
Phase I of the Clean Air Act Amendments (CAAA) of 1990 is complete, and has resulted in a significant reduction in SO2 emissions from utility power plants in the eastern United States (as of 2000, the last year that emissions data are available). Reduced SO2 emissions, especially fom the Ohio River Valley area, were a major focus of Phase I. Little or no improvement in NOx emissions reductions has occurred in the eastern United States, except for NY, PA, and the New England area.
Several subregions of the eastern United States were evaluated individually, and relations between emissions of SO2 and NOx to precipitation and air chemistry were established. The regions evaluated include: northern New England and the Adirondack Mountain Region, lower NY, PA, Mid-Atlantic, OH and vicinity, IL and vicinity, and the southern Appalachian Mountains. Strong relations between SO2 emissions and sulfur deposition components were found in all regions except the southern Appalachians. Declines in SO2 emissions from source regions (based on 15-hour back trajectories of air masses for the New England area and 9-hour back trajectories of air masses for the remaining study areas) led to comparable declines in precipitation SO42-, and air concentrations of SO2 and particulate SO42- (representative of dry deposition). There also were strong linear relations between declines in combined emissions (SO2 plus NOx) and precipitation acidity. The Illinois region showed somewhat weaker relations for precipitation SO42-. The weakest relations were found in the southern Appalachian Region, where declines in SO2 emissions from appropriate source regions showed no accompanying declines in precipitation acidity, and only small declines in precipitation SO42- concentrations. NOx emissions have increased in this area during the 1990s. The southern Appalachian Mountains are an acid sensitive region, where declines in acidic deposition are necessary to protect sensitive surface waters and high elevation forests.
When data from all study areas are combined to obtain a representative estimate of relations for emissions and concentrations for the eastern United States as a whole (not including the deep South, which was not evaluated in this study), there are near 1:1 relations for SO2 emissions versus precipitation SO42- concentrations, SO2 emissions versus air concentrations of SO2 and particulate SO42- (i.e., dry deposition components), as well as for combined emissions of SO2 and NOx versus H+ concentrations (acidity).
Initial results for establishing relations between NOx emissions and wet and dry nitrogen deposition components were at first not successful. However, with the addition of more recent years of data (up to 2000), disaggregation of the NOx emissions into vehicle and non-vehicle emissions, and a more powerful regression modeling technique (mixed model analysis), we recently have established significant relations for NOx emissions and precipitation chemistry NO3-, for four regions (New England, New York, Pennsylvania, and the Mid-Atlantic) of the seven regions studied. Our preliminary results suggest that reductions in NOx emissions, based on 9-hour air mass back trajectories, lead to reduced precipitation NO3-. Initial analysis suggests that a 50 percent reduction in total emissions result in a 42 percent (± 7 percent standard error) reduction in NO3- concentration (and deposition). If non-vehicle emissions were reduced by 50 percent (which is a 24 percent reduction in total emissions) precipitation NO3- would be reduced by 21 percent (± 3 percent standard error). Both models show approximately a 1:0.85 relation between changes in NOx emissions and precipitation NO3-. Comparable impacts on precipitation acidity also are expected.
All of the above results have implications for legislation regarding controls of both SO2 and NOx emissions. Reductions in either form of pollutant emissions resulted in comparable reductions in components of wet and dry sulfur deposition (near 1:1 relations), and components of wet nitrogen deposition (1:0.85 relations). In the future, we hope to assess the impact of NOx emission changes on nitrogen dry deposition components (i.e., HNO3 aerosols and particulate NO3-).
Journal Articles on this Report : 3 Displayed | Download in RIS Format
| Other project views: | All 7 publications | 3 publications in selected types | All 3 journal articles |
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Butler TJ, Likens GE, Stunder BJB. Regional-scale impacts of Phase I of the Clean Air Act Amendments in the USA:the relation between emissions and concentrations, both wet and dry. Atmospheric Environment 2001;35(6):1015-1028. |
R826760 (2001) R826760 (Final) |
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Driscoll CT, Lawrence GB, Bulger AJ, Butler TJ, Cronan CS, Eagar C, Lambert KF, Likens GE, Stoddard JL, Weathers KC. Acidic deposition in the northeastern United States: sources and inputs, ecosystem effects, and management strategies. BioScience 2001;51(3):180-198. |
R826760 (Final) |
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Likens GE, Butler TJ, Buso DC. Long-and short-term changes in sulfate deposition: effects of the 1990 Clean Air Act Amendments. Biogeochemistry 2001;52(1):1-11. |
R826760 (2000) R826760 (2001) R826760 (Final) |
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Supplemental Keywords:
atmospheric deposition, acidic deposition, sulfur dioxide, nitrogen oxides, emissions, nitrogen deposition, sulfur deposition, acid rain., RFA, Scientific Discipline, Water, Ecosystem Protection/Environmental Exposure & Risk, Nutrients, Environmental Chemistry, Ecosystem/Assessment/Indicators, Ecosystem Protection, Restoration, Ecological Effects - Environmental Exposure & Risk, Environmental Monitoring, Ecological Risk Assessment, Ecology and Ecosystems, Aquatic Ecosystem Restoration, Ecological Indicators, aquatic ecosystem, hydrological stability, precipitation, ecological exposure, monitoring, nutrient sensitive ecosystems, regional economies, bioavailability, chemical transport, Sulfur dioxide, sulfur, emissions, hydrogen ion, atmospheric nitrogen deposits, nitrogen oxide, nutrient stress, wet and dry deposition, SO2, sulfur compounds, precipitation chemistry, ecosystem, Clean Air Act, nitrogen compounds, water quality, ecosystem stress, rainfall, public policy, regulations, ecological impact, acid rain, climatology, nitrogenRelevant Websites:
http://www.ecostudies.org Exit
Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.