Physicochemical water quality of the Mfoundi River watershed at Yaoundé, Cameroon, and its relevance to the distribution of bacterial indicators of faecal contamination

Water quality of the Mfoundi River and four of its tributaries was studied by assessing some physicochemical variables (temperature, pH, conductivity, chlorides, phosphates and nitrogen ammonia, dissolved oxygen and carbon dioxide, organic matter content and Biological Oxygen Demand) and their influence on the distribution of bacterial indicators of faecal contamination (total coliform, faecal coliform and faecal streptococci). For this, standard methods for the examination of physicochemical parameters in water were followed, and statistical analysis (Pearson correlations) used to establish any relationships between physicochemical and biological variables. Our results revealed that almost all of the examined physicochemical variables exceeded World Health Organization (WHO) guidelines for recreational water. This was in agreement with a previous microbiological study indicating that these waters were not safe for human use or primary contact according to water quality standards established by the WHO. Results of our correlation analysis suggested that physicochemical and biological variables interact in complicated ways reflecting the complex processes occurring in the natural environment. It was also concluded that pollution in the Mfoundi River watershed poses an increased risk of infection for users and there exists an urgent need to control dumping of wastewater into this watershed.

Microbiological water quality of the Mfoundi River watershed at Yaoundé, Cameroon, as inferred from indicator bacteria of fecal contamination

Using the membrane filtration technique to count total coliform (TC), fecal coliform (FC) and fecal streptococci (FS), the microbiological water quality of the Mfoundi River and four of its representative tributaries at Yaoundé, Cameroon, was assessed for human use and contact. Sampling was conducted so as to examine the potential origin of fecal contamination and how rainfall affects the measured concentrations of indicators organisms. Our results revealed that waters were not safe for human use or primary contact according to the standards for water quality established by the Word Health Organization (WHO). Indeed, these waters exhibited high concentrations of TC (Mean +/- SD = 5.6 x 10(8) +/- 2.5 x 10(6) CFU/100 ml), FC (Mean +/- SD = 6.8 x 10(5) +/- 2.4 x 10(3) CFU/100 ml) and FS (Mean +/- SD = 7.3 x 10(5) +/- 2.1 x 10(3) CFU/100 ml) that varied with the sampling sites and points. FC/FS ratio suggested that this contamination was more from warm-blooded animals than humans and correlation analysis points to the role of rainfall as a contributing factor, which enhanced the bacterial numbers detected. We conclude that there is a great potential risk of infection for users of waters from the Mfoundi River and its tributaries at Yaoundé.