Associations between pollutant emissions and precipitation chemistry: An empirical analysis

Abstract

Empirical analyses were conducted of the associations between anthropogenic SO2 emissions and precipitation SO42− concentrations as well as between anthropogenic NOx emissions and precipitation NO3− concentrations across central North America. Both the 1982 Electric Power Research Institute (EPRI) National Air Pollutant Emissions Inventory and the 1985 National Acid Precipitation Assessment Program (NAPAP) Emissions Inventory, along with precipitation chemistry data from up to 130 monitoring sites, were used in the analyses. Comparisons of the EPRI and NAPAP emissions inventories in their geographic area of overlap indicate that SO2 emissions differ more than do the NOx emissions, on both absolute and fractional difference scales. Empirical analysis results indicate that the associations between anthropogenic SO2 emissions and precipitation SO42− are stronger than associations between anthropogenic NOx emissions and precipitation NO3− concentrations, with the associations equally well represented by either a power law or linear law function. Distinct regional and seasonal differences exist in the strength of the associations.