Yearlong variability of oxidative potential of particulate matter in an urban Mediterranean environment. (1st June 2019)

• Record Type: Journal Article
• Authors: Paraskevopoulou, D.; Bougiatioti, A.; Stavroulas, I.; Fang, T.; Lianou, M.; Liakakou, E.; Gerasopoulos, E.; Weber, R.; Nenes, A.; Mihalopoulos, N.
• Is Part Of: Atmospheric environment. Volume 206(2019)
• Page Start: 183
• Page End: 196
• Publication Date: 2019-06-01
• Subjects: Oxidative potential -- Reactive oxygen species -- DTT assay -- Particulate matter -- Toxicity -- Urban aerosol; Air -- Pollution -- Periodicals; Air -- Pollution -- Meteorological aspects -- Periodicals; 551.51
• DOI: 10.1016/j.atmosenv.2019.02.027
• Languages: English
• ISSNs: 1352-2310

Abstract

Abstract: The oxidative potential (OP) of fine and coarse fractions of ambient aerosols was studied in the urban environment of Athens, Greece. OP was quantified using a dithiothreitol (DTT) assay, applied to the water soluble fraction of aerosol that was extracted from 361 fine and 84 coarse mode of 24-h and 12-h filter samples over a one-year period. During the cold period, samples were collected on a 12-h basis, to assess the impact of night-time biomass burning emissions from domestic heating on OP. The chemical characteristics of aerosols were measured in parallel using an Aerosol Chemical Speciation Monitoring (ACSM) and a 7-wavelength Aethalometer. A source apportionment analysis on the ACSM data resulted in the identification of organic aerosol (OA) factors on a seasonal basis. A good correlation of OP with NO3 −, NH4 +, BC (Black Carbon), Organics and LV-OOA (low volatility oxygenated OA) was found during winter, revealing the importance of combustion and aging processes for OP. During the summertime, a good correlation between OP and SO4 −2 and NH4 + indicates its association with regional aerosol – thus the importance of oxidative aging that reduces its association with any characteristic source. Multiple regression analysis during winter revealed that highly oxygenated secondary aerosol (LV-OOA) and, to a lesser extent, fresh biomass burning (BBOA) and fossil fuel (HOA) organic aerosol, are the prime contributors to the OP of fine aerosol, with extrinsic toxicities of 54 ± 22 pmol min −1 μg −1, 28 ± 7 and 17 ± 4 pmol min −1 μg −1, respectively. In summer, OP cannot be attributed to any of the identified components and corresponds to a background aerosol value. In winter however, the regression model can reproduce satisfactorily the water soluble DTT activity of fine aerosol, providing a unique equation for the estimation of aerosol OP in an urban Mediterranean environment. Graphical abstract: Image 1 Highlights: Yearlong oxidative potential measurements on 367 fine aerosol samples. Fine urban aerosol oxidative potential is 3 times higher compared to coarse mode. Winter elevated oxidative potential attributed to fresh aerosol emissions. Summer background aerosol oxidative potential due to long-range transport. Satisfactory reconstruction of fine aerosol water-soluble dithiothreitol activity.