Chemical characterization of precipitation from a monitoring network in the lower Ohio river valley

Abstract

Abstract The Kentucky Acid Deposition Program (KADP) precipitation chemistry network was initiated in 1983 with the goal of providing a statewide monitoring system to document the occurrence of acid deposition in Kentucky. A variety of analyses have been performed on the KADP data for the period 1983–1989 to characterize precipitation chemistry in the lower Ohio River Valley. H2SO4 and HNO3 are identified as the primary contributors to precipitation acidity in this region, with HCl playing a secondary role. Neutralization of precipitation acidity occurs both as a result of the dissolution of alkaline compounds containing Ca2+, Mg2+, and K+ as well as the absorption of NH3 vapor. H+, SO42+, and NO3−precipitationn concentrations exhibit a seasonal pattern in which higher concentrations are observed during summer months and lower concentrations during winter months. The seasonal behavior of NH4+ concentrations, however, differs from this pattern in that the highest concentrations occur during spring months while the lowest values occur during autumn. Annual depositions of SO42−, NO3−, Cl−, NH4+, Ca2+, and H+ show no apparent qualitative temporal trend over the 1985–1989 period in this region.