Physico-Chemical Analysis of Eutrophication’s Parameters in a Coastal River (Côte D’ivoire)

Abstract

A study on some physico-chemical and biological variables of water quality was conducted on a coastal river in Ivory Coast. It’s the first assessment on water quality state. Those coastal rivers actually play an important role in the physical, biological and hydrological exchange between lagoons and the sea. Unfortunately, they are not taken into account by the national monitoring for water quality (RNO-CI). The samples were collected along Boubo River body through three stations, in the south of Cote d’Ivoire, during two years. Results show sharp fluctuations of the concentration N- NO 3 - nitrate, N- N H 4 + ammonium and chlorophyll a with more than 20% variation. However, small fluctuations were noted for temperature, pH and conductivity with 4% - 20%. Measures are generally inferior to the threshold for hazardous water class. But respective average concentrations of N- NO 3 - , P- PO₄<sup style="margin-left:-7px;">3-</sup> , COD and BOD5 are above natural water threshold, representing 67% of the analyzed samples of P- PO₄<sup style="margin-left:-7px;">3-</sup> and 100% of the other. These results show that the river is not exempt of pollution: 0.2 mg/l of P- PO₄<sup style="margin-left:-7px;">3-</sup> and 0.9 mg/l of N- NO 3 - are the limits of appropriate siege for the proliferation of invasive aquatic plants (IAP).