Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8864702 | Atmospheric Research | 2018 | 14 Pages |
Abstract
Integrating nephelometer measurements have been combined with co-located in space and time PM10 and PM1 mass concentration measurements to highlight the benefits of integrating aerosol optical properties with the chemical speciation of PM1 and PM10 samples. Inorganic ions (SO42â, NO3â, NH4+, Clâ, Na+, K+, Mg2+, and Ca2+), metals (Fe, Al, Zn, Ti, Cu, V, Mn, and Cr), and the elemental and organic carbon (EC and OC, respectively) have been monitored to characterize the chemical composition of PM1 and PM10 samples, respectively. The scattering coefficient (Ïp) at 450â¯nm, the scattering Ã
ngström coefficient (Ã
) calculated at the 450-635â¯nm wavelength pair, and the scattering Ã
ngström coefficient difference (âÃ
) retrieved from nephelometer measurements have been used to characterize the optical properties of the particles at the surface. The frequency distribution of the Ã
daily means during the one-year monitoring campaign, performed at a southeastern Italian site, has allowed identifying three main Ã
variability ranges: Ã
â¯â¤â¯0.8, 0.8â¯<â¯Ã
â¯â¤â¯1.2, and Ã
â¯>â¯1.2. We found that Ïp and âÃ
mean values and the mean chemical composition of the PM1 and PM10 samples varied with the Ã
variability range. Ïp and âÃ
reached the highest (149â¯Mmâ1) and the smallest (0.16) mean value, respectively, on the days characterized by Ã
â¯>â¯1.2. EC, SO42â, and NH4+ mean mass percentages also reached the highest mean value on the Ã
â¯>â¯1.2â¯days, representing on average 8.4, 9.8, and 4.2%, respectively, of the sampled PM10 mass and 12.4, 10.6, and 7.7%, respectively, of the PM1 mass. Conversely, Ïp and âÃ
mean values were equal to 85â¯Mmâ1 and 0.55, respectively, on the days characterized by Ã
â¯â¤â¯0.8 and the EC, SO42â, and NH4+ mean mass percentages reached smaller values on the Ã
â¯â¤â¯0.8â¯days, representing 4.5, 6.0, and 1.9% of the PM10 mass and 9.4, 7.3, and 5.8% of the PM1 mass, respectively. Primary and secondary OC (POC and SOC, respectively) contributions also varied with the Ã
variability range. POC and SOC mean mass percentages reached the highest and the smallest value, respectively, on the days characterized by Ã
â¯>â¯1.2. Conversely, POC and SOC mean mass percentages reached the smallest and the highest value, respectively, on the days characterized by Ã
â¯â¤â¯0.8. It has also been shown that the PM, OC, OCâ¯+â¯EC, POC, and SOC mass scattering cross sections varied significantly with the Ã
variability range, because of the Ã
dependence on aerosol sources and/or emission, transport, and transformation mechanisms. Therefore, it has been shown that Ã
daily mean values can represent a good tool to better differentiate the chemical speciation of size-fractioned PM samples.
Keywords
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Atmospheric Science
Authors
M.R. Perrone, S. Romano, A. Genga, F. Paladini,