||Illinois State Water Survey Div., Champaign.; Illinois Univ. at Urbana-Champaign.; Department of Agriculture, Washington, DC.; Department of the Interior, Washington, DC.; Environmental Protection Agency, Washington, DC.
This report presents data summaries from three networks. Contour maps present NTN data. Concentration and deposition maps present MDN data. The bar charts present AIRMoN concentrations over time. The NTN maps portray spatial variability in the concentration and deposition of selected acids, nutrients, and base cations on regional and national scales. Only sites that meet prescribed data completeness criteria are included. In 2002, 195 sites met these criteria. Annual concentration or deposition values are printed next to each site. The concentrations are volume-weighted averages. The MDN maps show the concentration and deposition of total mercury in precipitation. Only sites meeting prescribed data completeness criteria are included. In 2002, 54 sites met these criteria. Annual concentration or deposition is printed next to each site. The concentrations are volume-weighted averages. The AIRMoN data shown by bar charts show wet and dry deposition of sulfur (S) at the Bondville AIRMoN-wet and AIRMoN-dry site in central Illinois. Each bar in the top chart depicts S deposition in kilograms per hectare (kg/ha) for a meteorological season. The 1998 meteorological winter is December 1997 through February 1998. Spring is March through May, etc. The AIRMoN-wet deposition is the product of the seasonal precipitation amount and precipitation-weighted-mean S from sulfate. The AIRMoN-dry deposition is the S deposition from aerosol sulfate and the S deposition from gaseous sulfur dioxide. Dry depositions of S from aerosol sulfate and gaseous sulfur dioxide were calculated using atmospheric concentrations, meteorological data, and information on land use, vegetation, and surface conditions. Individual measurement programs use different methodologies, which can result in large differences in S deposition estimates.