Biomonitoring of air pollutants by using lichens (Evernia prunastri) in areas between Kenitra and Mohammedia cities in Morocco.

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.

Sufrimiento y pesimismo en Schopenhauer

El presente artículo investiga de qué forma la centralidad del sufrimiento en la filosofía de Schopenhauer sirve para fundamentar su pesimismo. Tres son los argumentos analizados: el lugar del sufrimiento en el mundo, su lugar en la conciencia humana y su lugar frente a la felicidad. A la luz de estos tres argumentos, se destaca que el vínculo indisoluble entre el sufrimiento y la esencia del mundo, la determinación del sufrimiento en la conciencia, tanto en su génesis como en su intensidad, y su anterioridad ontológica frente a la felicidad hacen del pesimismo una categoría necesaria. Finalmente, se señala una posible contribución del pesimismo schopenhaueriano a la crítica social contemporánea, considerando la idea de mundo que el capitalismo tardío promueve.