Chemistry of precipitation at high altitudes: Inter-relation of acid-base components

Abstract

Data on the chemical composition of atmospheric precipitation for three high altitude WMO stations have been analyzed and critically interpreted using statistics of deposition and various ratio values. The stations are: Monte Cimone, Italy; Mauna Loa, HI, U.S.A.; and Alamosa, CO, U.S.A. The composition is quite variable, both within-station and station-to-station. There is a good correlation between reported alkalinity and Ca content for Monte Cimone. The data analysis suggests that H 2SO 4 is the main cause of “acid rain” at Mauna Loa. Two of the three stations show good association of NH 4 + ion with NO 3 − ion while the former is not well correlated with SO 4 2− ion at any of the stations. On the other hand, simple and multiple correlations indicate that sulfate is strongly related with alkali/alkaline earth elements. Thus, suspended particulate matter may be an important sink for the mass-removal of atmospheric sulfur in the lower troposphere.