In this study, Evernia prunastri, a lichen growing in its natural habitat in Morocco was analysed for the concentration of five heavy metals (Fe, Pb, Zn, Cu and Cr) from eleven sites between Kenitra and Mohammedia cities. The control site was Dar Essalam, an isolated area with low traffic density and dense vegetation. In the investigated areas, the concentration of heavy metals was correlated with vehicular traffic, industrial activity and urbanization. The total metal concentration was highest in Sidi Yahya, followed by Mohammedia and Bouznika. The coefficient of variation was higher for Pb and lower for Cu, Zn and Fe. The concentrations of most heavy metals in the thalli differed significantly between sites (p<0.01). Principal component analysis (PCA) revealed a significant correlation between heavy metal accumulation and atmospheric purity index. This study demonstrated also that the factors most strongly affecting the lichen flora were traffic density, the petroleum industry and paper factories in these areas. Overall, these results suggest that the index of atmospheric purity and assessment of heavy metals in lichen thalli are good indicators of the air quality at the studied sites.

parietina as a biomonitor of airborne heavy metal pollution in forest sites in the North East of Morocco. Lazaroa 36: 13-41 (2015).Xanthoria parietina, common foliose lichen, growing in its natural habitat, was analysed for the concentration of five heavy metals (Fe, Cr, Zn, Pb and Cu) from different forest sites of North East of Morocco (Kenitra, Sidi Boughaba, Mkhinza, Ceinture Verte near Temara city, Skhirat, Bouznika and Mohammedia). The quantification was carried out by inductively coupled plasma -atomic emission spectrometry (ICP-AES). Results were highly significant p<0,001. The concentration of metals is correlated with the vehicular activity and urbanization. The total metal concentration is highest at the Kenitra area, followed by Ceinture Verte site near Temara city, which experience heavy traffic throughout the year. Scanning electron microscopy (SEM) of particulate matter on lichen of Xanthoria parietina was assessed as a complementary technique to wet chemical analysis for source apportionment of airborne contaminant. Analysis revealed high level of Cu, Cr, Zn and Pb in samples near roads. parietina como biomonitor de contaminación por metales pesados en el aire en bosques del nordeste de Marruecos. Lazaroa 36: 31-41 (2015).Se ha realizado el análisis sobre la concentración de cinco metales pesados (Fe, Cr, Zn, Pb y Cu) en talos de Xanthoria parietina, líquen folioso común que crece en distintos bosques del noreste de Marruecos (Kenitra, Sidi Boughaba, Mkhinza, ciudad Ceinture Verte cerca de Temara, Skhirat, Bouznika y Mohammedia). La cuantificación se llevó a cabo por plasma de acoplamiento inductivo -espectrometría de emisión atómica (ICP-AES). Los resultados fueron altamente significativos p <0.001. La concentración de metales se correlaciona con la actividad motora y la cercanía de núcleos urbanos. La concentración total de metal es más alta en la zona de Kenitra, seguido de Ceinture Verte sitio cerca de la ciudad de Temara, que experimenta el tráfico pesado durante todo el año. La microscopía electrónica de barrido (SEM) de material particulado sobre líquenes de Xanthoria parietina se evaluó como una técnica cualitativa omplementaria al análisis químico para estimar la cantidad de contaminantes en el aire. El análisis reveló alto nivel de Cu, Cr, Zn y Pb en muestras cerca de las carreteras.Palabras clave: Biomonitorización de la contaminación del aire, plasma acoplado inductivamente, espectrometría de emisión atómica, microscopía electrónica de barrido.