Characterization of chemical species in PM2.5 and PM10 aerosols in suburban and rural sites of central Taiwan

Aerosol samples for PM,, (particulate matter with aerodynamic diameters les s than 2.5 mu m), PM2.5-10 (particulate matter with aerodynamic diameters b etween 2.5 and 10 mu m) and TSP were collected from June to September 1998 at THU (suburban) and HKIT (rural) sites in central Taiwan. The ratios of P M2.5/PM10 averaged 0.70 for the daytime and 0.63 for the nighttime at THU, respectively. At HKIT, the PM2.5/PM10 ratios averaged 0.56 for the daytime and 0.72 in the nighttime, respectively. These results indicated that the P M10 concentrations contribute the majority of the PM10 concentration and PM 10 concentrations contribute the majority of the TSP at both sites. The ave raged PM10 concentrations at THU are higher than those measured at HKIT dur ing the daytime period. However, the average PM2.5-10 concentrations in THU are lower than those measured at HKIT during nighttime. The samples collec ted were also analyzed by atomic absorption spectrophotometry for the eleme ntal analysis of Ca, Fe, Pb, Zn, Cu, Mn and Cr, Meanwhile ion chromatograph y was used to analyze for the water-soluble ions: sulphate, nitrate and chl oride in the Universal samples. The concentrations of heavy metals in PM10 during daytime were all higher than nighttime at THU. However, the averaged concentrations of metal elements in PM10 during day and night period were distributed irregularly at HKIT. The results indicated that for metal eleme nts collected at HKIT have different emission sources. The concentrations o f metal elements during daytime in PM10 at THU were generally higher than H KIT. The phenomena owing to the averaged PM10 particle concentrations at TH U (suburban) were higher than those measured at HKIT (rural) and PM,, occup ied the major portions of PM10 for both sites during the day period. For an ion species, there are no significant differences between day and night per iod in PM10 concentrations at both suburban and rural sites. (C) 1999 Elsev ier Science B.V. All rights reserved.