Influence of Monsoonal Driving Factors on the Secondary Inorganic Aerosol over Ambient Air in Dhaka
| Published | 19 August 2021 |
|---|---|
| Journal | ACS Earth and Space Chemistry |
| Volume | 5 |
| Issue | 9 |
| Pages | 2517-2533 |
| Publisher | American Chemical Society (ACS) |
| DOI | 10.1021/acsearthspacechem.1c00200 |
Urban and indoor air quality in Dhaka
Abstract
Secondary inorganic components significantly contribute to the modification of ambient aerosol properties by forming haze or reducing visibility. This study characterizes the water-soluble components in PM 2.5 and explores secondary inorganic aerosol (SIA) over the air in Dhaka, Bangladesh, throughout 2019. PM 2.5 samples were collected on a 24 h basis using a high-volume air sampler, and water-soluble inorganic compositions were measured using an ion chromatograph (IC). The observed PM 2.5 may pose potential health risks given that their 24 h mean exceeds the ambient air quality guidelines proposed by the World Health Organization (WHO) and the Department of Environment (DoE) of Bangladesh. Among the ions, SO 4 2–, Ca 2+, and NO 3 – were identified as the predominant species that account for 51, 20, and 11% of all soluble components, respectively. The soluble ions in PM 2.5 were relatively higher in the summer monsoon (13.26 ± 6.12 μg/m 3 ), possibly due to a combination of rampant anthropogenic activities and the pre-monsoonal meteorology. Humid summer plays a significant role in increasing the amount of SIA through the liquid-phase oxidation of precursor gases. Therefore, scavenging of ions may potentially occur (23% from the overall mean of ions) during the long rainy monsoon season over Dhaka. The anthropogenic origins of PM 2.5, such as transportation, industry, and construction dust, are widely present in natural sources all over Dhaka. Dust was more sensitive to enriched PM 2.5 than ions from a seawater origin. Excluding winter data, K + may significantly resuspend from urban dust over Dhaka. The elements and molecular tracer technique reveal that the potential reactive ions (e.g., Cl –, SO 4 2–, and NO 3 – ) were more sensitive to anthropogenic human activities in Dhaka air than to seawater and terrestrial soil. The influence of converting vehicle fleets into compressed natural gas (CNG) run and upgrading kiln technology on increasing SO 4 2– aerosol in Dhaka is yet to be investigated.
Abstract © the authors and American Chemical Society (ACS).
Cite this
Nur Hidayah Norazman, Md Firoz Khan, Sharanya Ramanathan, Syazwani Mustapa Kama Shah, Siti Jariani Mohd Jani, Khaled Shaifullah Joy, Kazi Naimul Islam, Farah Jeba, Abdus Salam, Otoha Yoshida, Hiroto Kawashima (2021). Influence of Monsoonal Driving Factors on the Secondary Inorganic Aerosol over Ambient Air in Dhaka. ACS Earth and Space Chemistry, 5(9), 2517-2533. https://doi.org/10.1021/acsearthspacechem.1c00200
Related work from the laboratory
Names in bold are laboratory members. The DOI links to the published paper.