Abstract
Ambient suspended particulate (dry deposition, TSP) was collected in the traffic sites Sha-Lu, central Taiwan. In addition, the related water-soluble ionic species (Cl 1/4, NO3 1/4, SO4 2 1/4, Na+, NH4 +, K+, Mg2 +and Ca2+) were analysed and wind speed, wind direction and temperature were also measured in this study. The downward dry deposition fluxes (averaged 54.07 mg/m2-sec) were about twice that of upward dry deposition fluxes (averaged 26.48 mg/m2-sec) in the daytime period. Furthermore, the average downward dry deposition fluxes (averaged 26.22 mg/m2-sec) were also about twice that of upward dry deposition fluxes (averaged 12.11 mg/m2-sec) in the night-time period. The results showed that the total suspended particulate concentrations of particulate mass in the daytime period (averaged 996.2 mg/m3) were higher than in the night-time period (averaged 560.7 mg/m3). The results showed that the total suspended particulate concentrations of particulate mass in the daytime period (averaged 996.2 mg/m3) were higher than in night-time period (averaged 560.7 mg/m3). As for water-soluble ionic species, the average dry deposition order and velocity for downward ionic species were Cl 1/4 Í-Ca2+Í-NO3 1/4 Í-K+(2.09 cm/sec Í-1.46 cm/sec Í-1.46 cm/sec Í-1.07 cm/sec) anions during the daytime period. And the average dry deposition order and velocity for downward ionic species were NO3 1/4 Í / Cl 1/4 Í / K+Í / Ca2+(2.92 cm/sec Í / 2.74 cm/sec Í / 0.96 cm/sec Í / 0.93 cm/sec) anions during the night-time period. The average dry deposition order and velocity for upward ionic species were Cl 1/4 Í / Ca2+Í / K+Í / Mg2 +(4.69 cm/sec Í / 0.62 cm/sec Í / 0.59 cm/sec Í / 0.55 cm/sec) anions during the daytime period. And the average dry deposition order and velocity for upward ionic species were Cl 1/4 Í-Ca2+Í-Mg2 +Í-K+(1.65 cm/sec Í-0.43 cm/sec Í / 0.37 cm/sec Í / 0.33 cm/sec) anions during the night-time period. The results also indicated that the sodium and chloride concentrations in total suspended particulate were highly positively related, indicating that the sea-salt aerosols were the major contributors for these species at this sampling site of central Taiwan.
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