An assessment of sulfur deposition pathways in Asia

The acid deposition model is developed and applied to assess the sulfur dep osition pathways in Asia. Simulations for four seasons are conducted: Febru ary, April, August, and October. The predicted results of summer and winter are compared to measured concentration of SO,, sulfate, and sulfate wet de position in Japan. Further comparison of sulfate wet deposition to observat ions in China is made to assess the general performance of the model. The s tudy shows that wet deposition is more important than dry deposition. It is the predominant factor in each of these four months. It is also found that rainout process, compared to washout process, make a larger contribution t o sulfate wet deposition in summer and spring than in the dry months, such as October. The total sulfur wet to dry deposition ratio is 1.6 in February , 1.2 in April, 2.9 in August, and 1.9 in October. (C) 1999 Elsevier Scienc e Ltd. All rights reserved.