Impact des rejets industriels sur l'environnement: Cas de l'accumulation du chrome dans les différents compartiments aquatiques le long du littoral Casablanca - Mohammadia

Abstract

In Morocco, in the absence of wastewater standards, industrial wastewaters are discharged without any preliminary treatment into the natural environment, particularly the marine environment. The objective of the present work was to study the impact of industrial wastewater discharge with high chromium (Cr) content regarding the bioaccumulation of this metal by molluscs, fish, algae and sediments. Eight stations were chosen for sampling over a five-year period (Summer 1998 to Winter 2002) in the littoral area between Casablanca and Mohammadia. The highest Cr contents accumulated by the molluscs were detected along the Oued El Malleh (S2) and Oukacha (S6) sites (18.7 and 14.4.mg/kg dry weight, respectively). This situation is attributed to high discharges of industrial wastewater from Mohammadia and Ain Sebâa. High Cr concentrations (300 mg/kg dry weight) were detected in the sediments at these two sites. At site S6, the two algae species studied showed high Cr contents: 9.70 and 25.90 mg/kg dry weight in Ulva lactuca and Corallina officinalis, respectively. The results of the Cr accumulation in two fish species, the mule Mugil cephalus and the sar Diplodus sargus, showed a higher content in the mule. Also, the comparative study of Cr accumulation between the various biological compartments shows that the mollusc Mytilus galloprovincialis is an excellent bioindicator of pollution by Cr, showing the highest concentrations when compared to other species of algae and fish. Copyright © 2006, CAWQ.