Keywords: acid aerosols, annular denuder, MOUDI, ions, size distribution, Taiwan
Sampling errors in the study of acid gases and anion species in atmospheric aerosols
Atmospheric acid aerosols were sampled by two annular denuder systems (ADS) and a micro-orifice uniform deposit impactor (MOUDI) at a traffic site in central Taiwan. Theoretical analysis showed that the relative artifact for HNO3 gas sampling was about 0.53 when the initial HNO3 concentration was under 0.2 µg/m³ and should be considered carefully. The concentrations of gaseous acid at the traffic sampling site were higher than those in the other study. The size distributions of acid aerosols were unimodal for Cl-, NO2-, and NO3-, and bimodal for SO42-. The dominant acid ions in particles less than 18 µm were SO42-, NO3-, NO2- and Cl-.