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Characterization and Source Apportionment of Fine Particulate Matter Chemical Components in Two Districts of Lanzhou City’s Atmosphere

Qin Cui , Jianyun Sun, Yufang Fan, Yongjun Li

Abstract

Rationale: The characterization and sources of the chemical composition of fine particulate matter in the atmosphere are of critical importance to the environment and human health. As the capital of Gansu Province with a population of more than 4 million and one of the important industrial cities in western China, it is of urgent practical significance to study the characterization and sources of atmospheric fine particulate matter chemical constituents in Lanzhou City. Methodology: In this study, monitoring was carried out from January 2018 to June 2022 in Chengguan and Xigu districts, and a total of 702 valid samples were collected. Measurements included PM2.5 mass concentrations, water-soluble ions, metals, metalloids, and polycyclic aromatic hydrocarbons (PAHs) in both districts. Results: The results showed that PM2.5 mass concentrations in both districts exhibited a decreasing trend throughout the study period, with seasonal variations characterized as high in winter and spring, and low in summer and autumn. The concentration of water-soluble ions follows the order of SO42- > NO3- > NH4+ > Cl-, with a seasonal distribution pattern of winter > autumn > spring > summer (P<0.05). The concentrations of metals and metalloids were higher in Xigu District than in Chengguan District, following a seasonal pattern of spring > winter > autumn > summer (P<0.05). PAHs concentrations were significantly higher in Chengguan District than in Xigu District (P<0.05), with a seasonal pattern of being high in winter and low in summer (P<0.05). Discussion: The main sources of PM2.5 in Lanzhou City as originating from dust, secondary pollution, industry, biomass burning, traffic, and coal combustion. Dust sources were the most significant contributors in Chengguan District (37.6%), while secondary pollution sources were predominant in Xigu District (40.9%), suggesting that previous initiatives to relocate industrial areas away from cities and other management measures have been quite effective. The results provide valuable insights and a scientific basis for enhancing the prevention and control of atmospheric PM2.5 pollution in Lanzhou City.

EN24057  Accepted 27 October 2024

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