Monitoring of heavy metal contamination in soils and terrestrial isopods sampled from the industrialized areas of Sfax (southeastern Tunisia)

摘要

To evaluate the influence of soil contamination on the distribution of terrestrial isopods, species richness, relative abundance, and diversity, various indices were studied in 20 sampling sites from five industrial areas located in Sfax (SE Tunisia). The following hypotheses were tested: (1) is isopod diversity affected by soil properties? (2) What are the environmental factors that influence the isopod distribution? A total of 445 individuals were sampled and eight species of terrestrial isopods were identified. Porcellionides pruinosus was the most abundant species (38%); however, the highest specific richness per area was equal to four species. To evaluate the impact of metal contamination on isopod distribution, cadmium (Cd), lead (Pb), zinc (Zn), copper (Cu), and iron (Fe) concentrations were measured in soils and terrestrial isopods. Moreover, multivariate analyses revealed a negative correlation between heavy metal concentrations and ecological parameters suggesting an impact of the contamination degree on biodiversity. In addition, to characterize the heavy metal accumulation in isopods, the bioaccumulation factor (BAF) was determined and revealed that Cu and Zn were the most accumulated elements. Results showed that for all species, the order of the BAF values is as follows: Cu Zn Cd Pb Fe. On the contrary, all species seemed to be deconcentrators of Fe and Cd, with some exceptions.