SOURCE-RECEPTOR RELATIONSHIPS FOR WET SO4(2-) AND NO3(-) PRODUCTION

Precipitation chemistry data for the years 1982-1985 from 110 stations distributed across the continental U.S. and southern Ontario Province are used to describe the geographic distributions of SO42- and NO3- in precipitation. Volume-weighted, wet SO42- and NO3- concentrations, averaged over the 4 years of observation by season and annullly, show coherent patterns with maxima in the northeastern U.S. and southeastern Canada about ten times greater than the minima observed in the Intermountain and Pacific Northwest regions. Tests for empirical source-receptor relationships indicate that, in land areas with relatively low emissions of SO2 and NOx, the associations between wet SO42- concentrations and SO2 emissions and between wet NO3- concentrations and NOx emissions within 560 km of each precipitation chemistry station are weak or nonexistent (r2≤0.42). The remaining land areas show moderate to strong associations between SO2 and SO42- and NOx and NO3- during the spring and summer, but only weak to nonexistent associations during the winter. The associations between emissions and concentrations, e.g. SO2 and SO42-, are equally well represented by either a linear or a power law function. However, at the level of aggregation employed, the data do not substantiate a linear-proportional relationship between concentrations and anthropogenic emissions. Furthermore, emissions of SO2 and NOx are highly correlated, as are the emissions of RHC and NOx. © 1990.