Caractérisation de la pollution de l'air par les particules et les éléments métalliques dans la ville de Constantine

Abstract

The measurement of fine dust in Constantine has never been carried out so far. It is, therefore, of utmost importance to address this problem in order to estimate particulate matter (PM) concentration levels, to assess the exposure of residents to PM10 and PM2,5, to identify potential sources of the collected particles and propose lines of work that could provide answers to the troublesome contribution of road traffic to the measured PM urban levels. Two sampling sites were selected. The first sampling site was located in the urban area of Daksi which is characterized by heavy traffic heading towards the city center to the south and the residential areas to the north. The second site was located at the entrance of the campus of the Faculty of Earth Sciences at Zouaghi and is close to national road 79, where traffic is among the heaviest in the city of Constantine. Statistical techniques have been successfully used to identify and characterize the sources of PM and trace metals. The application of factor analysis and enrichment factors allowed to identify polluting sources such as soil dust resuspension, the earth's crust and urban traffic as the main sources of PM. The tram's construction site on the other side of the road along the measurement site was another important anthropogenic nearby source. Traffic is causing high levels of Pb because Algeria is one of the few countries to use lead additives in gasoline. To identify external sources and their geographical position, air mass back-trajectories were calculated with HYSPLIT4 model. Saharan dust was identified as a major source of PM and Fe. The Mediterranean sea was identified as the main source of Na, Mg, K and Ca.