The present study investigates the geochemical behaviour of PM10 aerosol constituents (Cl, Na, Si, Al, Ca, Fe, Mg, Mn, Pb, Zn, S) at Sfax City (Tunisia) under succeeding meteorological conditions, including short-lived anticyclonic, cyclonic and prolonged anticyclonic situations. The results revealed daily total concentrations fluctuating between 4.07 and 88.51 μg/m(3). The highest level recorded was noted to occur under the effect of the short-lived anticyclonic situation characterized by low wind speeds. It was 1.5 times higher than those recorded during cyclonic and long-lived anticyclonic situations characterized by moderate to high wind speeds. During the cyclonic situation, the marked increase of (Na and Cl) concentrations is associated with relatively high sea wind speeds (6 to 9 m/s), which are in turn responsible for a slight increase of crustal elements such as Al, Ca, Si, Fe and Mg, by the entrainment in the air of dust from roads and undeveloped areas. During the two anticyclonic situations, the simultaneous increase (due to communal transport) of crustal (Ca, Si, Al, Fe, Mg) and man-made (Mn, S, Pb, Zn) elements was noted to be associated with the dominance of terrigenious wind flows with speeds varying between 1.5 and 4 m/s. However, the significant contribution rates observed for Cl under the prevalence of such winds as compared to other crustal elements such as Fe suggested the influence of the sebkhas of Southern Tunisia.

In order to better understand the processes of removing atmospheric particles to the surface, dry particle deposition in Monastir region (eastern Tunisia) has been studied. As a first step, a biweekly monitoring of the particulate deposits was carried out in 26 sites from January to August, 2012. Secondly, two particular sites were investigated from October, 2014 to August, 2015. A very high fluctuation in those particle fluxes, ranging from 0.560 to 2.210 g/m2/14days, was clearly observed. The spatial distribution of particulate deposits shows a growing trend from rural to urban (coastal) areas depending on nearby sources (brickyards and clay quarries, road traffic and sebkhas) and meteorological factors (including precipitation and wind speed). The combined geochemical-statistical study of the particulate deposits elementary fluxes (Cl-, Na+, K+, Ca++, Fe(2,3)+, Cd, Pb, Zn, Ni, Mn and Cu) at the two observed rural and urban sites show a non-negligible impact of the anthropogenic component attributed to metals (Pb, Mn, Zn, and Cu). It is linked to the simultaneous effect of the urban (mainly road) activities in the Eastern part of the region and the intense fluidity of the motorway and railway in its Western part. The importance of the chlorine contributions of the terrigenous circulation has been attributed to the effect of sebkhas. The phenomenon of dust resuspension in agricultural areas, clay storage near brickyards and unbuilt sites has also been highlighted. The lowest biweekly elementary fluxes are probably due to the effect of rainfall periods which causes atmospheric whash-out.

Particle deposition in three selected "urban/suburban" sites in Sfax city, southern Tunisia, was studied through biweekly monitoring particulate deposits from April 12 to November 26, 2014. Two sites (S1 and S2) were located at the proximity of well-exposed cross-roads; however, the third (S3) was located at a street canyon. A very high fluctuation in those particle fluxes, ranging from 0.1 and 17.9 g/m(2), was clearly observed. Spatiotemporal distribution of the deposited particulate fluxes proved the concomitant effects of multiple (local and synoptic) sources. The industrial contribution rate in terms of particulate deposits was demonstrated to be negligible, and as for that of traffic, it was confirmed to be more significant. The highest particulate deposition seemed to be associated with the sirocco wind phenomenon. Humidity appeared as a main parameter reinforcing the particle deposition (by gathering process); however, the rain was considered as an important factor in terms of atmosphere washing. The intersite distribution was also threatened by local wind movements, shown as a non-negligible factor in terms of deposition, especially in the street canyon.

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