Influence of fireworks displays on the chemical characteristics of PM2.5 in rural and suburban areas in Central and East China.

To explore the spatial and chemical characteristics of PM2.5 pollution and the influence of fireworks displays on PM2.5 and its chemical components in rural areas in Central and East China, PM2.5 samples were collected at three rural sites and one suburban site in Henan and Shandong provinces during the 2016 Chinese New Year, and the chemical composition of PM2.5, including water-soluble inorganic ions (WSIIs), organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC) and trace elements (TEs) was analysed. The concentrations of PM2.5 at the four sites were significantly higher than the Grade I national standard of 35μg/m3, indicating serious PM2.5 pollution in rural and suburban areas. The contributions of secondary WSIIs to total WSIIs at the four sites were lower than in urban areas. The TEs in XP and LC were significantly enriched in PM2.5. A significant difference was found in the main chemical compositions of different sites. Fireworks displays directly increased the concentrations of PM2.5 and many chemicals, especially K+, Cl-, K, Cl, S, Cu and Sr, and concentrations of NO3- and NH4+ ions peaked after the fireworks period in the three rural sites, indicating the influence of firecrackers on the secondary formation of the precursors of NO2. The ratio of WSOC/OC decreased during fireworks displays, indicating the direct influence of firecrackers on water insoluble organic matter. Fireworks-related ions were a key component of the aerosol at the four sites during fireworks displays, accounting for 28-38% of the total measured species.