PRECIPITATION-CHEMISTRY MEASUREMENTS FROM THE CALIFORNIA ACID DEPOSITION MONITORING PROGRAM, 1985-1990

The configuration of the California Acid Deposition Monitoring Program (CADMP) precipitation network is described and quality assurance resu lts summarized. Comparison of CADMP and the National Acid Deposition P rogram/National Trends Network (NADP/NTN) data at four parallel sites indicated that mean depth-weighted differences were less than 3 mueq l -1 for all ions, being statistically significant for ammonium, sulfate and hydrogen ion. These apparently small differences were 45-30% of t he mean concentrations of ammonium, sulfate and hydrogen ion. Mean dep th-weighted concentrations and mass deposition rates for the period 19 85-1990 are summarized; the latter were highest either where concentra tions or precipitation depths were relatively high.