Trend and source apportionment of atmospheric PM_2.5 chemical component pollution in Yinchuan City, China, 2015—2022

Objective  To analyze the trend and sources of atmospheric fine particulate matter (PM_2.5) and its chemical component pollution in Yinchuan City, China from 2015 to 2022, and to provide a basis for scientific emission reduction and better control of atmospheric PM_2.5 pollution in Yinchuan City.

Methods  Two sampling sites were set up in the urban area of Yinchuan and regular monthly atmospheric PM_2.5 sampling was conducted. The daily atmospheric PM_2.5 mass concentration was measured using the gravimetric method. The concentrations of PM_2.5-bound metal or metalloid elements and polycyclic aromatic hydrocarbons (PAHs) were determined using inductively coupled plasma mass spectrometry and high-performance liquid chromatography. The sources of PM_2.5-bound metal or metalloid elements and PAHs were analyzed using the enrichment factor analysis and characteristic ratio method, and the sources of atmospheric PM_2.5 were comprehensively analyzed.

Results  The mass concentration of atmospheric PM_2.5 in Yinchuan City showed a downward trend from 2015 to 2022, but the mean annual mass concentrations of PM_2.5 exceeded the secondary concentration limit (35 μg/m³) specified in the Ambient Air Quality Standards (GB 3095-2012) in all years. The mass concentrations of PM_2.5-bound metals, metalloids, and PAHs showed a decreasing trend, and the difference between years was statistically significant. The proportions of metal elements aluminum, manganese, lead, and PAHs fluoranthene, pyrene, benzobfluoranthene, and chrysene were continuously high. The chemical components of PM_2.5 in the atmosphere of Yinchuan City mainly came from coal-burning pollution, traffic pollution, combustion of liquefied petroleum fuels, and waste incineration pollution. From 2015 to 2017, coal-burning pollution and traffic pollution were equally severe. From 2018 to 2022, coal-burning pollution decreased.

Conclusion  The air quality of Yinchuan City shows an improving trend, but the pollution situation is still severe, with coal-burning pollution and traffic pollutioncoexisting, accompanied by combustion of liquefied petroleum fuels and waste incineration pollution.