Résumé:
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.
