A numerical simulation of annual acid deposition amount in Korea

A comprehensive acid deposition model was used to calculate an annual amount of acid deposition in North East Asia as well as to derive a source–receptor relation. The model results for gaseous SO2 and O3 agree very well with measurements, but the model under-estimated NO2 concentrations. Similarly, the model estimates the sulfate in rain waters quite well but under-estimates nitrate in the rain waters. The correlation coefficients for the spatial distributions of the calculated and measured annual mean concentrations were 0.97, 0.63 and 0.90 for the gaseous SO2, O3, and NO2. One-third of SO2 emitted in North East Asia was calculated to be advected out mostly in the form of sulfate. The amount removed by dry deposition is comparable to that removed by wet deposition for sulfur but it is 40% larger than that by wet deposition for nitrogen. The source–receptor relations derived by the counter-species method show that the wet deposition is more influenced by the long-range transport than the dry deposition. Furthermore, the long-range transport contribution was calculated to be the lowest in the summer and the highest in the winter.