Seasonal and spatial variability of secondary inorganic aerosols in PM2.5 at Agra: Source apportionment through receptor models

• Published in: Chemosphere (Oxford) Vol. 242; p. 125132
• Main Authors: Agarwal, Awni, Satsangi, Aparna, Lakhani, Anita, Kumari, K. Maharaj
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.03.2020
• Subjects: Aerosol acidity; Biomass burning; PM2.5; Positive matrix factorization; Principal component analysis; Water soluble inorganic ions; Aerosol acidity; Water soluble inorganic ions; Biomass burning; PM2.5; Principal component analysis; Positive matrix factorization
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2019.125132

The present study was conducted at sub-urban and rural site of Agra. The main aim of this study was to characterize WSII in terms of spatial, seasonal and formation characteristics and identify the major sources responsible for the pollution of WSII in PM2.5 particles using different source apportionment models. Since biomass burning is one of the most important sources of PM2.5 pollution in Agra, a case study was also conducted at rural site to investigate the contribution of biomass burning from cooking activities using different types of fuels. PM2.5 mass concentrations were higher at sub-urban site (91.0 ± 50.8 μg/m3) than at rural site (77.1 ± 48.6 μg/m3). WSII contributed 50.0% and 45.8% of annual average PM2.5 mass at both sites. The aerosols were ammonium rich and were therefore alkaline in nature. Aerosol acidity characteristics studied using AIM-II model showed that the aerosols were slightly less acidic at rural site than at sub-urban site. SO42−, NO3− and NH4+ were the major contributors of WSII and their formation was favoured mainly in winter. Although, WSII showed slight variations in seasonal and spatial characteristics, the major sources of pollution were found to be similar. Four sources were identified as biomass burning (29.1% and 27.4%), secondary aerosols (26.2% and 22.5%), coal combustion (22.3% and 26.9%) and soil dust (22.4% and 23.1%) at sub-urban and rural sites. The results of case study showed that among different types of biomass fuels cow dung cakes showed maximum PM2.5 emissions while LPG showed minimum PM2.5 emissions. •Water Soluble Inorganic Ions (WSII) in PM2.5 varied both seasonally and spatially.•Sulphate, nitrate and ammonium formation is favoured mainly in winter season.•Biomass Burning is the major source of pollution at both sub-urban and rural sites.•WSII contribute nearly 50% and 45.8% to PM2.5 mass at the two sites.•Cow dung cakes lead to maximum PM2.5 emissions.