Spatial Characteristics and Regional Transmission Analysis of PM(2.5) Pollution in Northeast China, 2016–2020

Northeast China is an essential industrial development base in China and the regional air quality is severely affected by PM(2.5) pollution. In this paper, spatial autocorrelation, trajectory clustering, hotspot analysis, PSCF and CWT analysis are used to explore the spatial pollution characteristics of PM(2.5) and determine the atmospheric regional transmission pattern for 40 cities in Northeast China from 2016 to 2020. Analysis of PM(2.5) concentration characteristics in the northeast indicates that the annual average value and total exceedance days of PM(2.5) concentration in Northeast China showed a U-shaped change, with the lowest annual average PM(2.5) concentration (31 μg/m(3)) in 2018, decreasing by 12.1% year-on-year, and the hourly PM(2.5) concentration exploding during the epidemic lockdown period in 2020. A stable PM(2.5) pollution band emerges spatially from the southwest to Northeast China. Spatially, the PM(2.5) in Northeast China has a high degree of autocorrelation and a south-hot–north-cool characteristic, with all hotspots concentrated in the most polluted Liaoning province, which exhibits the H–H cluster pattern and hotspot per year. Analysis of the air mass trajectories, potential source contributions and concentration weight trajectories in Northeast China indicates that more than 74% of the air mass trajectories were transmitted to each other between the three heavily polluted cities, with the highest mean value of PM(2.5) pollution trajectories reaching 222.4 μg/m(3), and the contribution of daily average PM(2.5) concentrations exceeding 60 μg/m(3) within Northeast China. Pollution of PM(2.5) throughout the Northeast is mainly influenced by short-range intra-regional transport(,) with long-range transport between regions also being an essential factor; organized integration is the only fundamental solution to air pollution.