Characteristics of submicron particles coming from a big firecrackers burning event: Implications to atmospheric pollution

Özet

Firecrackers burning on different occasions all over the world is a short-term big source of fine particles and their precursors in the air. This study presents the realtime changes in concentrations, composition and characteristics of non-refractory particulate matter smaller than 1 μm aerodynamic diameter (NR-$PM_1$), and blackcarbon (BC) during the Diwali festival, when a huge amount of firecrackers are burnt in India. Online measurements (1 min integration time) of organics, $SO_4^{2-}4$ , $NO_3^-$ , $NH_4^+$ , and $CI^-$ were performed using high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS), and that of BC with seven wavelength aethalometer overa big urban city (Ahmedabad, 23.0ºN, 72.6ºE) in western India. A sharp increase (3–23 times higher) in the concentrations of all the measured species was observedon the evening of the Diwali that persisted overnight due to a combination of primary emissions and secondary formation of aerosol. Organics were the dominantcontributor (∼85%) followed by $SO_4^{2-}4$ (∼13%), $CI^-$(∼4%), $NO_3^-$ (∼4%) and $NH_4^+$ (∼2%) to NR-$PM_1$ on the Diwali night. Further, variations in H/C and O/C ratiosbefore, during and after the Diwali suggest fresh emissions of primary organics on the Diwali night, and highly oxidized secondary organic formation on the next day.Aerosol neutralization ratio (ANR, defined as the molar ratio of $NH_4^+$ to sum of $SO_4^{2-}4$, $NO_3^-$ and $CI^-$ ), an indicative of aerosol acidity, reduced to as low as 0.1 on theDiwali night, which has implications to short-term acute atmospheric air pollution.