Stable carbon and nitrogen isotopic characteristics of PM2.5 and PM10 in Delhi, India

This study presents the chemical composition (carbonaceous and nitrogenous components) of aerosols (PM2.5 and PM10) along with stable isotopic composition (δ13C and δ15N) collected during winter and the summer months of 2015–16 to explore the possible sources of aerosols in megacity Delhi, India. The mean concentrations (mean ± standard deviation at 1σ) of PM2.5 and PM10 were 223 ± 69 µg m−3 and 328 ± 65 µg m−3, respectively during winter season whereas the mean concentrations of PM2.5 and PM10 were 147 ± 22 µg m−3 and 236 ± 61 µg m−3, respectively during summer season. The mean value of δ13C (range: − 26.4 to − 23.4‰) and δ15N (range: 3.3 to 14.4‰) of PM2.5 were − 25.3 ± 0.5‰ and 8.9 ± 2.1‰, respectively during winter season whereas the mean value of δ13C (range: − 26.7 to − 25.3‰) and δ15N (range: 2.8 to 11.5‰) of PM2.5 were − 26.1 ± 0.4‰ and 6.4 ± 2.5‰, respectively during the summer season. Comparison of stable C and N isotopic fingerprints of major identical sources suggested that major portion of PM2.5 and PM10 at Delhi were mainly from fossil fuel combustion (FFC), biomass burning (BB) (C-3 and C-4 type vegitation), secondary aerosols (SAs) and road dust (SD). The correlation analysis of δ13C with other C (OC, TC, OC/EC and OC/WSOC) components and δ15N with other N components (TN, NH4+ and NO3−) are also support the source identification of isotopic signatures.