Identification of Atmospheric PM2.5 Sources Using Isotopes Techniques-Pilot Study
Absrtact |
The objectives of this study are to develope analytical methods for determination of isotopes in fine particulate matters (PM2.5) and to feasibility of identifying potential sources of ambient PM2.5 with the isotopic fingerprints. To achieve the objectives, ambient PM2.5 sampling was carried out at the Cap Fuguei (CAFÉ), Taipei (NTU), Yangminshan, Douliu and Chayi stations. Besides, in order to establish isotope fingerprints of specific sources, vehicle-emitted particles were collected in the Hsuehshan Tunnel and coal materias together with fly ash and bottom ash were collected from coal-fire power plants. These samples were analyzed for water soluble ions, elemental carbon, organic carbon and metallic constituents. In addition, carbon along with lead and stronitium isotopes were also determined by cavity ring-down spectrometry (CRDS) and multi-collector inductively plasma mass spectrometer (MC-ICP-MS), respectively. The results showed that organic carbon, which accounted for 15-41% of PM2.5 mass, was the predominant species, followed by non-sea-salt sulfate (14-29%), ammonium (6-13%), nitrate (2-16%) and elemental carbon(2-9%). The elevated abundance of OC in the summertime was attributed to the formation of secondary organic aerosols, whereas lower nitrate concentrations were due to evaporation under high atmospheric temperature. Elevated level of sea salt particles was observed at CAFÉ station located in the coastal area, whereas EC and nitrate were found enriched in PM2.5 samples collected at downtown stations.
Using CRDS and MC-ICP-MS instruments, C, Pb and Sr isotopes in PM2.5 samples were detected with high precision and accuracy. The averaged δ13CTC in PM2.5 at CAFÉ and NTU stations were -26.7 and -27.0‰ during summertime, which were lighter than those in the spring period by 2.5‰. The stable carbon isotope ratio measured in the summertime were representative of the local emissions as Taiwan was isolated from continental
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Keyword |
PM2.5, Isotope, Source Identification, Long-range Transported pollutants
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