||Acidic Gases and Aerosols in the Eastern and Western United States.
Edgerton, E. ;
Martin, B. E. ;
||Environmental Science and Engineering, Inc., Durham, NC.;Environmental Protection Agency, Research Triangle Park, NC. Atmospheric Research and Exposure Assessment Lab.
Air pollution sampling ;
Long term effects ;
United States ;
US EPA ;
Data base management ;
Sulfur dioxide ;
Nitric acid ;
Eastern Region(United States) ;
Western Region(United States) ;
National Dry Deposition Network
||Some EPA libraries have a fiche copy filed under the call number shown.
||The USEPA National Dry Deposition Network (NDDN) is designed to provide long-term estimates of acidic gas and aerosol concentrations, and associated fluxes, across the continental United States. Inspection of data collected since 1988 shows species-dependent variability in atmospheric concentrations from site to site, season to season and year to year. In general, gas and aerosol concentrations were much higher (factor of 2-10) at eastern sites than western sites. Data for 25 eastern sites operational from 1988 through 1991 suggest that SO4(-2) concentrations have been essentially constant. In contrast, SO2 and HNO3 appear to have decreased, on average, by about 20 percent and 15 percent, respectively. Examination of sub-regional concentration patterns shows marked variability in areas of complex terrain. Data from a ridgetop site and a nearby base elevation site in southwestern North Carolina show that reactive gas concentrations, but not aerosol concentrations, are 2-3 times higher at ridgetop than at base elevation. Elevational gradients thus need to be accounted for in analysis of large-scale concentration patterns.
||Sponsored by Environmental Protection Agency, Research Triangle Park, NC. Atmospheric Research and Exposure Assessment Lab.
||PC A03/MF A01