Source Apportionment of PM10 and PM2.5 at a Traffic Site in Constantine, Algeria: Combining Back-Trajectory Analysis and Correlation Studies

This study investigated PM10 and PM2.5 concentrations, major components, trace elements, and source identification at a traffic site near Zouaghi in Constantine, Algeria, from February 2021 to November 2021. The mean PM10 and PM2.5 concentrations were 150 ± 103 µg/m ³ and 55 ± 42 µg/m ³ , respectively, exceeding WHO air quality guidelines (2021). Coarse particles predominated, reflecting soil dust resuspension, and trace elements were concentrated in the PM10-2.5 fraction. Four distinct sources were identified using cluster back-trajectory analysis: the Sahara, Mediterranean Sea, northwest, and Atlantic Ocean. PM10 and 17 metal elements (Sb, Ba, Al, Ca, Mg, Fe, K, Na, Cu, Pb, V, Zn, Ti, Mn, Ni, Mo, and Sr) were enriched in air masses from the Sahara, Mediterranean Sea, and northwest, suggesting contributions from natural and anthropogenic sources. Correlation analysis revealed that well-correlated pollutants were transported by air masses from the same back-trajectory groups, indicating a common origin. Enrichment factors helped distinguish between natural and anthropogenic sources. The consistency between correlation analysis and back-trajectory clustering reinforced the effectiveness of these methods for source apportionment of PM10-related metallic elements. This study validated the efficacy of correlation analysis and back-trajectory clustering as tools for identifying PM sources in Constantine, providing a cost-effective approach for understanding PM origins and composition. These findings enabled the proposal of targeted interventions, such as traffic flow improvements and industrial emission controls, to mitigate pollution levels and inform public health officials in developing strategies to protect population health.