The effect of the physicochemical conditions variations on the behavior of heavy metals trapped in polluted fluvial system sediments : the case of Ouest Sebou, Morocco

This study was an attempt to understand the factors influencing the heavy metal distribution in polluted fluvial system sediments. Various biogeochemical processes and anthropogenic factors were playing an important role in altering the concentration of heavy metals in the sediments. This paper has two objectives : the first one is to investigate the effect of the variation in the physicochemical conditions on the speciation of trace elements trapped in the sediments of the Sebou River. The second one is to study the kinetics mobilization of these heavy metals. Batch resuspension experiments were conducted in order to investigate the release of heavy metals from a polluted anoxic sediment submitted to different physicochemical conditions variations. It has been revealed that in oxygenated environment, sediments were oxidized which cause the release of some heavy metals, but their concentrations, as dissolved phase, were sustained constant or were increased with time. However, in acidic and anaerobic environment, most of the metallic trace elements were released together with the iron and the manganese, but some of these elements like chromium were precipitated. However, some of other elements were maintained in solution, which represents a real human health risk.