Physico-Chemical and Microbiological Qualities of Porto-Novo Lagoon Water

Abstract

This research aims at analyzing the physicochemical and bacteriological characteristics of lagoon’s waters in Porto-Novo. To reach this goal, a methodology is used based on documentary research, followed by data collection sampling and analysis of water samples, and surveys with the target populations. The water quality is assessed on the basis of physico-chemical and bacteriological analysis of collected water samples. The findings of the surveys on the physicochemical assessment of the water's suitability reveal that the temperature varies between 30.21 and 30.92°C, exceeding the norms (25°C), the conductivity varies between 109 µS/cm and 145 µS/cm, and the salinity varies between 0.05 and 0.07 psu. pH values are beyond the norm (5.86; 6.15; 6.27 and 6.28). The dissolved oxygen, total dissolved solids, suspended solids, chemical oxygen demand and biochemical oxygen demand vary respectively between 0.33 mg/L and 1.93 mg/L; 54 mg/L and 73 mg/L; 6 mg/L and 12 mg/L; 12 mg/L and 20 mg/L; 5 mg/L and 8 mg/L. The pollution caused by metals such as cadmium and plumb range respectively from 0.0195 to 0.219 mg/L and 0.03 to 0.065 mg/L, exceeding the guide values of the national standard (0.5 mg/L and 0.05 mg/L). Microbiologically, all the water samples contain very high quantities of faecal enterococci and Escherichia coli. These results show that human activities seriously pollute surface water resources and contribute to their decay