Concentration prediction and spatial origin analysis of criteria air pollutants in Shanghai.

Severe air pollution events still occur frequently in Shanghai. In order to predict when Shanghai air quality satisfies the National Ambient Air Quality Standards of China (NAAQSC) and identify potential source areas of criteria air pollutants for the regional joint prevention and control of air pollution, concentration data of PM 2.5 , PM 10 , SO 2 , NO 2 and O 3 were collected in 2014–2022 at fourteen monitoring sites across Shanghai and surrounding areas. A first – order rate equation with harmonic regression analysis was employed for time series analysis and concentration prediction. Decreasing concentrations were observed widely over all sites except O 3 and NO 2. It is very likely that the secondary NAAQSC standards for PM x , and SO 2 would be met by 2025 and O 3 and NO 2 would likely become the critical pollutants that determine air quality level after 2025. Regional transport was predominant for PM x and SO 2 pollution. A 3D – CWT multisite joint location method was developed to identify their potential source areas at different spatial resolutions. Weighting function correction was assigned via information entropy of endpoint numbers in each cell. A probabilistic parameter WI PSA was proposed to quantify and normalize the probability that grid cells are source areas in order to achieve fourteen – site joint location, and it was comparable and compatible at different spatial resolutions. Potential source areas of PM 2.5 and PM 10 were similar, including Henan, Shandong, Hebei and Anhui, while origin domains of SO 2 mainly covered Henan and Hebei. In all seasons, air pollution that was transported to Shanghai (i.e., PM x and SO 2) originated mainly from the North China Plain; the contribution of marine sources was neglectable. [Display omitted] • Declining concentrations of PM x and SO 2 were observed widely in Shanghai. • Local secondary standards for PM x and SO 2 would likely be met by 2025. • Regional transport was predominant for PM x and SO 2 pollution. • 3D-CWT multisite joint location identified accurately their potential source areas. • In all seasons Shanghai PM pollution originated mainly from the North China Plain. [ABSTRACT FROM AUTHOR]