UTILISATION D’INDICES POUR L’EVALUATION DE LA QUALITE DES SEDIMENTS : CAS DU BASSIN BOUMERZOUG (ALGERIE)

Abstract

The objectives of this study are to use different indexes to assess the current pollution status in Boumerzoug basin. Indexes used in this study were Geo-accumulation Index (Igeo), Contamination Factor (CF), Contamination Degree (CD) and Sediment Pollution Index (SPI). Before, sediment trace metal concentrations (cadmium, chromium, copper, lead, nickel, zinc) have been investigated on surface sediments from permanent wadis of Boumerzoug basin in different seasons (winter, spring, summer and autumn). Trace metal concentrations followed the order: Zn>Pb>Cr>Cu>Ni>Cd. Indexes used give several status of sediment quality. Igeo, CF, CD and SPI reveal a polymetallic contamination dominated by two or more elements in which Cd, Cu and Pb are of greatest concern. Igeo gives more precision than CF, because it is classified into six classes. SPI has an advantage over the earlier indexes and viewed as a simple summary of the state of the sediment. However, the trace metal assessment indices are not to be used as the only indicator for sediment quality. More detailed analysis such as biological testing and analysis of existing benthic community related to sediment contamination should be performed for a better understanding about the nature, the fate and the toxic effects of contaminants in this ecosystem.