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Microbiological water quality of the Mfoundi River watershed at Yaoundé, Cameroon, as inferred from indicator bacteria of fecal contamination Djuikom, E.; Njine, T.; Nola, M.; Sikati, V.; Jugnia, L.-B. Abstract. 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 × 10 8 ± 2.5 × 10 6 CFU/100 ml), FC (Mean ± SD = 6.8 × 10 5 ± 2.4 × 10 3 CFU/100 ml) and FS (Mean ± SD = 7.3 × 10 5 ± 2.1 × 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.

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An experimental passive methane oxidation biocover (PMOB) was constructed within the existing final cover of the St-Nicéphore landfill. Its substrate consisted of a 0.80-m thick mixture of sand and compost. The goal of this experiment was to evaluate the performance of the PMOB in reducing CH 4 emissions when submitted to an increasing methane load. The CH 4 load applied started with 0.3 g CH 4 m −2 h −1 . When the site had to be closed for the winter, the CH 4 input was 27 g CH 4 m −2 h −1 . Throughout the study, practically all the CH 4 input was oxidized, absolute removal rates were linearly correlated to methane loading, and the oxidation zone was established between 0.6-0.8 m. These results seem to indicate that the upper limit potential of this PMOB to oxidize CH 4 was not reached during the study period. Surface CH 4 concentration scans showed no signs of leaks. The substrate offered excellent conditions for the growth of methanotrophs, whose count averaged 3.91 x 10 8 CFU g dw -1 soil.

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We examined the impacts of remediation activities aimed at improving the water quality of hypereutrophic Villerest Reservoir, in which Microcystis aeruginosa dominated during the summer. We also compared nutrients and chlorophyll a data from this study with the results of a previous study on the reservoir. Between the two studies, the nitrogen and phosphorus loads into the reservoir from the main tributary decreased by 70% and 80%, respectively. Within the reservoir, the quantities of ammonianitrogen were similar in the two studies, and the total nitrogen was significantly higher in this study compared to the initial study. Both the phosphate-phosphorus and total phosphorus concentrations decreased significantly between the two studies. However, the statistically significant decrease in phosphate-phosphorus and total phosphorus did not always lead to a significant decrease in chlorophyll a concentrations. The nitrogen/phosphorus mass ratio during the present study remained well above five, the critical value below which summer blooms of Microcystis aeruginosa were observed in Villerest Reservoir. These study results indicated that the remediation activities being used to improve the water quality of Villerest Reservoir were off to a good start.

Significance and suitability of Aeromonas hydrophila vs. fecal califorms in assessing microbiological water quality Djuikom, E.; Njiné, T.; Nola, M.; Kemka, N.; Zébazé Togouet, S. H.; Jugnia, Louis-B. ORIGINAL PAPERSignificance and suitability of Aeromonas hydrophila vs. fecal coliforms in assessing microbiological water quality E. Djuikom AE T. Njiné AE M. Nola AE N. Kemka AE S. H. Zébazé Togouet AE Louis-B. Jugnia Abstract We examined the significance and suitability of Aeromonas hydrophila versus fecal coliforms in assessing microbiological water quality. For this, we used the membrane filtration method to simultaneously estimate the abundance level of A. hydrophila and fecal coliforms in waters from the Mfoundi river watershed at Yaoundé, and compared how fluctuations in A. hydrophila abundance matched those observed with fecal coliforms index as an indicator of water quality in the system under study. Our results revealed that waters were not safe according to the standards for water quality established by the Word Health Organization (WHO). They also indicated the prevalence of A. hydrophila as compared to fecal coliforms, and suggested that water from the Mfoundi River and its tributaries could be classified as hypereutrophic based on the density of Aeromonas. Moreover, the spatial distribution of fecal coliforms and A. hydrophila exhibited similar trends within the different water bodies investigated, suggesting that A. hydrophila can be used as indicator of water quality in highly polluted waters. We concluded that waters from the Mfoundi River watershed at Yaoundé represent a great potential risk of infection for users, and foresee that the next challenge will be to determine, among other factors, the physico-chemical factors influencing the observed spatial distribution.