Washout/rainout contribution in wet deposition estimated by 0.5 mm precipitation sampling/analysis

A precipitation dataset collected on a 0.5 mm precipitation basis was studied. The parameters analyzed in this study were the pH (i.e., H+ concentration), electric conductivity (EC), and SO42− and NO3− concentrations. The NO3− concentration clearly decayed with an increase of the precipitation amount, while a larger variation was observed in the SO42− concentration even when the precipitation amount increased. Assuming that the decaying NO3− concentration (0.70 μg ml−1) was the result of the rainout process, the estimates were: annual total deposition, 3252 mg m−2 yr−1; rainout process, 1092 mg m−2 yr−1; and rainout/total, 34%. The estimates for SO42− were: annual total deposition, 4687 mg m−2 yr−1; rainout process, 2096 mg m−2 yr−1; and rainout/total, 45%.