WET ACID DEPOSITION IN COLORADO

Precipitation and wet atmospheric deposition patterns were investigated for Colorado for the hydrologic year 1985. Above average precipitation for the year probably gave rise to higher than average deposition of sulfates and nitrates but this potential varied by season across the state and was higher at higher elevations. Average weekly concentrations of nitrates and sulfates were greatest during spring and summer and the average weekly pH of precipitation was lowest during the fall. Usually, average nitrate and sulfate concentrations decreased with increasing elevation while precipitation pH became more acidic with elevation. There was no clear pattern between acid concentration and increasing precipitation and elevation but precipitation pH decreased with increasing precipitation. Trajectory analysis suggested that important sources of acid precursors existed to the southwest of the state in 1985, but that areas to the northwest, west, and south, and regions within the state itself, are also likely sources.