TY - JOUR
T1 - Chemical Characterization and Source Apportionment of Organic Aerosols in the Coastal City of Chennai, India
T2 - Impact of Marine Air Masses on Aerosol Chemical Composition and Potential for Secondary Organic Aerosol Formation
AU - Kommula, Snehitha M.
AU - Upasana, Panda
AU - Sharma, Amit
AU - Raj, Subha S.
AU - Reyes-Villegas, Ernesto
AU - Liu, Tianjia
AU - Allan, James D.
AU - Jose, Christi
AU - Pöhlker, Mira L.
AU - Ravikrishna, Raghunathan
AU - Liu, Pengfei
AU - Su, Hang
AU - Martin, Scot T.
AU - Pöschl, Ulrich
AU - McFiggans, Gordon
AU - Coe, Hugh
AU - Gunthe, Sachin S.
N1 - Publisher Copyright:
©
PY - 2021/11/18
Y1 - 2021/11/18
N2 - Online chemical characterization of NR-PM1 (nonrefractory particulate matter ≤1 μm) has been carried out using an ACSM (Aerosol Chemical Speciation Monitor) at a coastal urban site in Chennai, India. The average mass concentration of NR-PM1 during the campaign was 30.4 ± 28.3 μg/m3 (arithmetic mean ± standard deviation) with organics accounting for a major fraction of ∼47.4% followed by sulfate (∼33.3%). Back trajectory analysis and STILT model simulations enabled the identification of a relatively clean period with prevailing air masses from ocean. During this period, the average NR-PM1 mass concentration was 7.1 ± 2.8 μg/m3, which is ∼5 times lower than that of the rest of the campaign (with air masses sampled from both continent and ocean) (33.3 ± 29.1 μg/m3). This reduction was primarily attributed to the dilution of local primary emissions due to cleaner marine influx. Comprehensive source apportionment for the organic fraction was performed using Positive Matrix Factorization (PMF). While equal contributions of primary (∼49%) and secondary (∼51%) organic factors were observed for the rest of the campaign, more oxidized-oxygenated organic aerosol (MO-OOA) factor dominated the OA and accounted for ∼82% of the total OA mass during the clean period. Simultaneously, during the clean period a significant increase in the fraction of organic liquid water was observed. We studied the effect of marine influx on the enhanced secondary organic aerosol (SOA) fraction. In brief, our results demonstrate the significance of marine winds and meteorological conditions on the chemical composition and ambient aerosol mass burden at a coastal site. Further, this study emphasizes that marine influx can cause the dilution in local pollution and can demonstrate distinct chemical composition with impacts on local aerosol properties.
AB - Online chemical characterization of NR-PM1 (nonrefractory particulate matter ≤1 μm) has been carried out using an ACSM (Aerosol Chemical Speciation Monitor) at a coastal urban site in Chennai, India. The average mass concentration of NR-PM1 during the campaign was 30.4 ± 28.3 μg/m3 (arithmetic mean ± standard deviation) with organics accounting for a major fraction of ∼47.4% followed by sulfate (∼33.3%). Back trajectory analysis and STILT model simulations enabled the identification of a relatively clean period with prevailing air masses from ocean. During this period, the average NR-PM1 mass concentration was 7.1 ± 2.8 μg/m3, which is ∼5 times lower than that of the rest of the campaign (with air masses sampled from both continent and ocean) (33.3 ± 29.1 μg/m3). This reduction was primarily attributed to the dilution of local primary emissions due to cleaner marine influx. Comprehensive source apportionment for the organic fraction was performed using Positive Matrix Factorization (PMF). While equal contributions of primary (∼49%) and secondary (∼51%) organic factors were observed for the rest of the campaign, more oxidized-oxygenated organic aerosol (MO-OOA) factor dominated the OA and accounted for ∼82% of the total OA mass during the clean period. Simultaneously, during the clean period a significant increase in the fraction of organic liquid water was observed. We studied the effect of marine influx on the enhanced secondary organic aerosol (SOA) fraction. In brief, our results demonstrate the significance of marine winds and meteorological conditions on the chemical composition and ambient aerosol mass burden at a coastal site. Further, this study emphasizes that marine influx can cause the dilution in local pollution and can demonstrate distinct chemical composition with impacts on local aerosol properties.
KW - Aerosol Liquid Water Content
KW - India
KW - Marine influx
KW - Nonrefractory PM
KW - Secondary Organic Aerosol
KW - Source apportionment
UR - https://www.scopus.com/pages/publications/85118154622
U2 - 10.1021/acsearthspacechem.1c00276
DO - 10.1021/acsearthspacechem.1c00276
M3 - Article
AN - SCOPUS:85118154622
SN - 2472-3452
VL - 5
SP - 3197
EP - 3209
JO - ACS Earth and Space Chemistry
JF - ACS Earth and Space Chemistry
IS - 11
ER -