Ambient air particulate dry deposition, concentrations and metallic elements at Taichung Harbor near Taiwan Strait

The purpose of this study is to characterize metallic elements associated with atmospheric particulate matter in dry deposition flux, total suspended particulate (TSP), fine particles (particle matter with aerodynamical diameter < 2.5 μm, PM2.5), coarse particles (particle matter with aerodynamical diameter 2.5–10 μm, PM2.5–10), and dry deposition velocity, at the Taichung Harbor sampling sites in central Taiwan during February to December of 2004. Also the average dry deposition velocities (for TSP) for metallic elements Fe, Zn, Mn, Cu, Pb, Cr and Mg were 2.6, 1.0, 1.9, 0.2, 1.7, 0.6 and 1.4 (cm s− 1), respectively, at the harbor sampling site. In addition, metallic element concentrations and compositions in fine and coarse particulate for air sampling were also analyzed in this study. The average total suspended particulate concentrations with metallic elements Fe, Zn, Mn, Cu, Pb, Cr and Mg were 116.3, 119.4, 148.8, 139.9, 46.1, 24.4 and 88.5 ng m− 3, respectively. The average ratios of coarse to fine for metallic elements Fe, Zn, Mn, Cu, Pb, Cr and Mg were about 1.9, 2.7, 3.8, 2.9, 1.6, 2.5 and 2.1, respectively. The results reflected that coarse particulate concentrations of metallic elements were the major species at the Taichung harbor sampling site. The results also identified dust, vehicle emissions and marine salt as the sources of fine particulates at Taichung Harbor near the Taiwan Strait. Most of the flux is due to particles larger than 2.5 μm in size due to their high deposition velocities. The result also indicates that the best approach to estimate overall dry deposition is by using either coarse particle or total particle concentrations.