Bioaccumulation of heavy metals in freshwater snails in relation to lining of water courses in Egypt.

Abstract

The present study was aimed to determine the heavy metal concentrations in whole body of fresh water snails in relation to lining of water courses in two governorates (Behaira (Nubaria) and Giza) Through four successive seasons from Septemper 2013, to October 2014. The obtained results indicated that the electrical conductivity (EC) and iron metal (Fe) showed the highest values and generally the physicochemical measurements indicated that no significant difference between the two tested habitats, however, the conductivity of water in lined water bodies was lower than those of unlined ones. The present study recorded 14 species of snails belonging to class Gastropoda; these species belonged to Pulmonate and Prosobranch snails. The density of all recorded Pulmonate snails in lined sites were lower than those in unlined ones. On the other hand, the abundance of Prosobranch snails was higher in numbers in the lined sites than those in the unlined. In Nubaria the most abundant snails were Melanoides tuberculata and Theodoxus niloticus and exhibited their maximum percentages in the lined (82.15%) and unlined (72.34%) sites during summer, respectively. While, in Giza Governorate Physa acuta snails had the highest percentages among collected snails approximately at all seasons, and exhibited its maximum percentages during spring in lined (90.22%) and unlined sites (85.38%). Correlations between physicochemical parameters and the collected snails, revealed that there were different negative or positive correlations depending on the sites of investigation. The bioconcentration factor of heavy metals in snail’s soft tissues at the investigated in lined and unlined sites compared to the content of the metals (Cd, Cu, Fe, Pb and Zinc) in the water showed high variation in BCF values depending on the type of metal and the snail. Generally P. acuta (7626.95μg.g-1 DW for Fe) and H. duryi (8787.10 μg.g-1 DW for Cu) were the highest snails of accumulated metal contents in the tested sites of the two surveyed governorates, respectively.