Dry deposition, ionic species measured and source interpretation during seasonal cycle at offshore areas near Taiwan Strait

The characterization for water-soluble species of total suspended particulate (TSP), dry deposition flux, and dry deposition velocity (Vd) were studied at Taichung Harbor (TH) and Wuchi traffic sampling sites at offshore sampling site near Taiwan Strait of central Taiwan during March 2004–January 2005. The average concentrations of TSP and dry deposition flux at the TH sampling site were higher than at the WT sampling site during the sampling period. The samples collected were analyzed by a ion chromatography (DIONEX-100) for the ionic species (Cl−, SO42-, NO3-, NH4+, Na+, Ca2+, and Mg2+) analysis. The dominant ionic species for TSP are SO42-, NO3-, and NH4+ of the total mass of the inorganic ions at both sampling sites. In addition, the results indicated that the NH4+, NO3- and SO42- showed higher concentrations in winter and lower in summer for both TH and Wuchi sampling sites. Statistical methods such as correlation coefficient and principal component analysis were also used to identify the possible pollutant source.