Abstract
ABSTRACTAn automated system consisting of a particle-into-liquid sampler (PILS) and a parallel plate wet denuder (PPWD) coupled with an ion chromatography was used for simultaneous measurement of ambient water-soluble ions in PM2.5 and precursor gases. The performance of the PPWD/PILS was validated by comparing it with the PDS (porous metal denuder sampler) for precursor gases (NH3, HONO, HNO3 and SO2) and PM2.5 ionic species (NH4+, NO3–, SO42–, Na+, Cl– and K+) measured in Taipei and Hsinchu Cities of Taiwan. Good correlations were demonstrated with linear regression slopes ranging from 0.92 to 1.04 and 0.84 to 0.97 as well as R2 ranging from 0.76 to 0.83 and 0.89 to 0.94, for precursor gases and PM2.5 ions, respectively. The accuracy of the current system for precursor gases outperforms the other commercial systems. Field continuous data showed that NH3 was the most abundant precursor gas with the diurnal pattern peaking at low nocturnal boundary heights and during rush hours with local traffic emissions in Taipei, and with the pattern peaking only at mid-day associated with regional sources in Hsinchu. A reverse diurnal pattern for HONO in Taipei reflected the daytime photolysis and its nocturnal heterogeneous reaction, while its concentration was relatively constant at very low level in Hsinchu. SO42–, NH4+ and NO3– exhibited very similar diurnal patterns with the mean concentrations of 4.56 ± 3.14, 1.55 ± 1.16 and 0.52 ± 0.5 µg m–3 in Taipei, and 7.95 ± 5.52, 2.41 ± 1.95 and 0.96 ± 1.10 µg m–3 in Hsinchu, respectively. Correspondingly high concentrations of major ions to precursor gases were associated with the photochemical secondary aerosol formations and heavy traffic in Taipei. Based on an ammonia-rich atmosphere and high SOR values, (NH4)2SO4 and NH4NO3 were inferred to be the dominant inorganic salts in PM2.5 at both sites, which were also verified by the ion balance analysis.
Highlights
Fine particulate matter (PM2.5, particles with aerodynamic diameters less than 2.5 μm) in the atmosphere are known to be associated with adverse effects on health, visibility reduction and climate change (Seinfeld and Pandis, 2006; Pope et al, 2009; Gautam et al, 2016; Patra et al, 2016)
An automated system consisting of a particle-into-liquid sampler (PILS) and a parallel plate wet denuder (PPWD) coupled with an ion chromatography was used for simultaneous measurement of ambient water-soluble ions in PM2.5 and precursor gases
This study presents the development, validation and field application of an automated instrument for simultaneous measurements of water-soluble PM2.5 ions and their precursor gases
Summary
Fine particulate matter (PM2.5, particles with aerodynamic diameters less than 2.5 μm) in the atmosphere are known to be associated with adverse effects on health, visibility reduction and climate change (Seinfeld and Pandis, 2006; Pope et al, 2009; Gautam et al, 2016; Patra et al, 2016). Water-soluble ions often constitute a significant fraction of PM2.5 mass (Lin et al, 2009; Chen and Tsai, 2010) and. Lung et al (2002) indicated that total ionic species accounted for 46.4% and 44.6% of PM2.5 mass on dust events and non-dust-event days, respectively in Taipei. Secondary aerosols (SO42–, NH4+ and NO3–) contributed approximately 50% and 60% of PM2.5 mass in spring and winter respectively; but were responsible about 40% by mass in summer at Tainan, Taiwan (Lu et al, 2016). Particulate organic matter (OM) contributed the most (18– 26%) to the annual average PM2.5, followed by SO42– (14– 19%), NO3– (10–11%), NH4+ (8–9%) and EC (3%), respectively, in Zhengzhou, China (Wang et al, 2016). Iberian Peninsula was mainly composed of organic matter and ammonium sulfate, while EC and nitrate were minor components (Galindo et al, 2016)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
