Volume-weighted mean concentrations of nitrate (NO3?), ammonium (NH4+), and sulfate (SO42?) in precipitation were compared at high-elevation sites in Colorado from 1992 to 1997 to evaluate emission source areas to the east and west of the Rocky Mountains. Precipitation chemistry was measured by two sampling methods, the National Atmospheric Deposition Program/National Trends Network (NADP/NTN) and snowpack surveys at maximum accumulation. Concentrations of NO3? and SO42? in winter precipitation were greater on the western slope of the Rockies, and concentrations of NO3? and NH4+ in summer precipitation were greater on the eastern slope. Summer concentrations in general were almost twice as high as winter concentrations. Seasonal weather [...]
