Dry deposition of atmospheric pollutants in Taiwan

Dry deposition pollutants were studied in Taiwan and compared with those reported in other areas of the world. The mean dry deposition fluxes in Taiwan were 2.40, 4.98 and 2.47 mu m/m(2)/sec for Taichung, Tainan and Pingtung, respectively. The correlation coefficients (R-2) Of mean dry deposition mass flux vs. wind speed were 0.47, 0.90 and 0.69 for Taichung, Tainan and Pingtung, respectively. Dry deposition mass fluxes in Taiwan were the same as in Chicago and about 3 times higher than in the North Sea. Suspended particle concentrations of metal elements (Ca, Fe, Zn, Cu and Cd) in Taiwan were much higher than in Chicago, Olympic and Ventura The results suggest that there is a greater heavy metal elements problem in Taiwan. The average dry deposition fluxes of total-PAHs in Taiwan were 622, 529 and 575 mu m/m(2)/sec at these three sampling sites. These were higher than reported in the Great Lakes, Siskiwit Lake and Chesapeake Bay, but were about the same as in Chicago. The total PAH compositions at the traffic sampling sites were 7275, 839 and 2450 mu g/g for Taichung, Tainan and Pingtung, respectively. The Taichung traffic sampling site had a larger total-PAM composition than the other two sampling sites. The total-PAM compositions in the rural sampling sites were 523, 645 and 531 mu g/g for Taichung, Tainan and PingTung, respectively. There was no significant difference for PAKs at the rural site of Taiwan. The cumulative fraction curve showed that atmospheric pollutants such as PAHs, sulfate, nitrate and heavy metals in Taiwan were mostly associated with fine particles (< 2.5 mu m). However, more than 95% of PCBs tended to be associated with particle size greater than 2.5 mu m.