Details

Autor(en) / Beteiligte

• Rajeev, Pradhi
• Choudhary, Vikram
• Chakraborty, Abhishek
• Singh, Gyanesh Kumar
• Gupta, Tarun

Titel

Light absorption potential of water-soluble organic aerosols in the two polluted urban locations in the central Indo-Gangetic Plain

Ist Teil von

• Environmental pollution (1987), 2022-12, Vol.314, p.120228-120228, Article 120228

Ort / Verlag

Elsevier Ltd

Erscheinungsjahr

2022

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• PM2.5 (particulate matter having aerodynamic diameter ≤2.5 μm) samples were collected during wintertime from two polluted urban sites (Allahabad and Kanpur) in the central Indo-Gangetic Plain (IGP) to comprehend the sources and atmospheric transformations of light-absorbing water-soluble organic aerosol (WSOA). The aqueous extract of each filter was atomized and analyzed in a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). Water-soluble organic carbon (WSOC) and WSOA concentrations at Kanpur were ∼1.2 and ∼1.5 times higher than that at Allahabad. The fractions of WSOC and secondary organic carbon (SOC) to total organic carbon (OC) were also significantly higher ∼53% and 38%, respectively at Kanpur compared to Allahabad. This indicates a higher abundance of oxidized WSOA at Kanpur. The absorption coefficient (babs-365) of light-absorbing WSOA measured at 365 nm was 46.5 ± 15.5 Mm−1 and 73.2 ± 21.6 Mm−1 in Allahabad and Kanpur, respectively, indicating the dominance of more light-absorbing fractions in WSOC at Kanpur. The absorption properties such as mass absorption efficiency (MAE365) and imaginary component of refractive index (kabs-365) at 365 nm at Kanpur were also comparatively higher than Allahabad. The absorption forcing efficiency (Abs SFE; indicates warming effect) of WSOA at Kanpur was ∼1.4 times higher than Allahabad. Enhancement in light absorption capacity was observed with the increase in f44/f43 (fraction of m/z 44 (f44) to 43 (f43) in organic mass spectra) and O/C (oxygen to carbon) ratio of WSOA at Kanpur while no such trend was observed for the Allahabad site. Moreover, the correlation between carbon fractions and light absorption properties suggested the influence of low-volatile organic compounds (OC3 + OC4 fraction obtained from thermal/optical carbon analyzer) in increasing the light absorption capacity of WSOA in Kanpur. [Display omitted] •Dominance of more oxidized organics at Kanpur during winter.•Higher light-absorption capacity (∼1.4 times) of water-soluble organics at Kanpur.•Enhancement in light absorption capacity with more oxidized organics at Kanpur.•Significant differences in the organic aerosol oxygenation at two sites.