Résumé:
Rhumel Wadi and its affluent Boumerzoug Wadi, one of the most important water
ressources in Constantine, are subject to urbain and industrial effluents. In order to assess the
level of trace metals contamination and the biological quality of thoes aquatic ecosystems, water,
fresh sediments, benthic invertebrates and an aquatic plant (Roripa nasturtium aquaticum) were
collected at stations along the Rhumel and Boumerzoug Wadi selected in an urban areas.
Concentration of cadmium, lead, chromium and manganese in the different compartiments were
determined by Atomic Absorption Spectroscopy. In addition, Biotic Index, and chemical
parameters of water and sediments were determined.
Results show, that heavy metals concentrations in water are not detectable, while an
enrichment of sediment appear, espacially for cadmium and lead. The determination of thoese
elements concentrations in Benthic invertebrates, indicate a probabel transfer from sediments
towards this aquatic fauna espicially for chromium and lead. As for Roripa nasturtium
aquaticum, the concentration of cadmium, lead, chromium and manganese in roots are greater
than in stems and leaves, indicating significant metal immobilisation by roots. Manganese
concentrations indicate a bioconcentration phenomenon for this plant, bioconcentration factors
are superior to 1. The decline of taxa richness is observed at downstream stations, which are
affected by wastewater and industrial effluents. The Biotic Index decreases dramatically from 8
at upstream stations to 2 at downstream station.