European Journal of Biotechnology and Bioscience European Journal of Biotechnology and Bioscience Online ISSN: 2321-9122, Impact Factor: RJIF 5.44 www.biosciencejournals.com Volume 5; Issue 4, July 2017; Page No. 42-47 Sustainable surface water quality monitoring in Bangui (Central African Republic) * Eric Foto, Olga Biteman Mobili, Oscar Allahdin, Nicole Poumaye, Joseph Mabingui UNESCO Chair, Lavoisier Hydrosciences Laboratory, University of Bangui, Faculté des Sciences, BP, BANGUI Abstract The study deals with the evolution of the physicochemical and bacteriological quality parameters that may be sources of surface water pollution in the city of Bangui in the Central African Republic. These parameters were monitored on a seasonal basis and are one of the first investigations to characterize the waters of the two main rivers of the city for their uses for the production of water intended for human consumption. In this context, the results provide a model for the monitoring and preservation of water resources in sub-Saharan regions facing the problem of climate change. Keywords: pollution, surface waters, quality, physicochemical 1. Introduction in collective sanitation of the neighborhoods, provides ideal Knowing the quality of superficial and underground natural basins for the proliferation of various pathogenic bacteria and waters is an essential element for individuals, economic germs. The malaria pandemic, the leading cause of death in activities, agriculture and communities. The Central African the country, is justified. These waters are naturally sensitive to Republic is a country with a high rate of rainfall. Its area is human pressures. The degradation of these waters is linked, on covered by both forest and savanna. But over the last 30 years, the one hand, to alterations in the physico-chemical quality of there has been a progression of the forest on the savannah, the water and, above all, to changes in their which is a situation currently exceptional in the world. There hydromorphological characteristics. are three seasons: the dry season runs from November to March, the intermediate season runs from April to June and 2. Localisation the rainy season from July to October. Natural water resources In our study, we looked at the Ubangi River (Figure 1a), are abundant: streams, rainwater, marshes and groundwater. which serves as a waterway during high water periods in the Unfortunately, all these resources are confronted with a Central African Republic. It is the main surface water resource problem of quality for human consumption. As the country is used for the drinking water supply of the city of Bangui. The virtually non-industrialized, pollution is mainly bacteriological Mpoko River (Figure 1b) in the southern part of the Bangui and organic. The profusion of water coupled with a deficiency region is smaller. Fig 1: a) Ubangi river in Bangui. b) Mpoko river Dupré (1996) [3] reports that the concentrations of dissolved particles are very low because of their high mobility during elements Ca, Na, Sr, K, Ba, Rb and U in the Ubangui and flood periods. Congo are remarkably low compared to other rivers. Patrick Seyler in 1996 [11] compares the dissolved metals of Moreover, the contents of these elements in the suspended the Ubangui and the Amazon with the average contents of the 42 European Journal of Biotechnology and Bioscience major world rivers. It also observes that these rivers whose world's rivers, the Ni, Cd and Rb levels are slightly higher, but basins are little anthropized, are little polluted. Compared to still below the pollution standards (Table 1). the average of the metallic contents in the waters of the Table 1: Concentrations of different dissolved elements in the Ubangui, Amazon and global averages (Seyler 1996) [11] To this end, we limited our study specifically to the - Collection: Sodéca collects approximately 1200 m3 / h. physicochemical and bacteriological parameters knowing that There is a ferry used for crossing the two countries. Two large the city does not have an industry. hotels are close to this site. - Upstream slaughterhouse: There is a center of commercial 3. Materials activities, especially for vegetables, fruits, and meat. Some of The following in situ analyzes were carried out on each water the litter related to this activity is discharged into the river point using the following materials: -pH (pH-meter WTW from a stream (Sapeke). A wild slaughter is also sometimes 340i), - Electrical Conductivity and Temperature (WTW 340i improvised on the shore, with washing offal. conductivity meter), -Alkalinity (Alkalinity HACH kit), - Oxi - Aval Abattoir: the only official slaughterhouse in Bangui. 330 / SET WTW Oximeter and then to the analytical Blood, offal and intestinal contents are discharged into the laboratory the devices used are - Hach turbidimeter, Precisa Ubangui through a channel constructed for this purpose. The XT 220A balance, WTW Oxi 330 / SET oximeter, - Uvikon population in this region is very dense. The pollution is mainly 860 Kontran spectrophotometer, Varian Spectra AA 55 atomic of human and animal origin. absorption spectrometer. The following equipment was used - Mpoko: Second River in size after the Ubangi. The samples for bacteriological analyzes: incubators, Petri dishes, filtration were taken about 2 km before the confluence with the ramp, sterile pipettes, filter membranes (0.45 mm), colony Ubangui. This region (south exit of Bangui) is very populated, counters, pliers, water bath and autoclave. A series of samples with no sanitary facilities. has been made for various chemical and bacteriological - Confluence Ubangui / Mpoko: The sampling was carried out analyzes which are then brought back to the laboratory in a in pirogue about 2 km after the mixing of the waters of the cooler Ubangui and the Mpoko at a distance about fifty meters from the bank. This region is sparsely populated. Pollution from the 4. Méthodology Mpoko should be greater during large waters. After a first phase of recognition of the sampling points on the ground by the Lavoisier laboratory team, three sampling 5. Results and Discussions campaigns one in high water on 17 November 2008; The On the samples taken, we carried out various bacteriological second in March 2009 low water; And the third in August and physicochemical analyzes. The results are shown in 2009. Intermediate flows were recorded in 6 sites: Figures 2, 3 and 4. A similarity can be observed between the - Ouango Saô: where the Bangui - Zongo (Democratic waters of the Mpoko and those collected 2 km from the Republic of Congo) river line is located, and there are strong confluence, showing that the mixture of water has not yet commercial activities between the two countries. One can taken place at the sampling point and that this sampling site estimate a crossing of twenty small boats per day, for tourism located 50 m from the right bank After the confluence is and goods. This region is sparsely populated. therefore little affected by the Ubangi. 43 European Journal of Biotechnology and Bioscience Fig 2: Variation of temperature in the different sites. Fig 3 Variation of conductivity in the different sites Fig 4: Variation of pH in the different sites. The temperature of the water, between 25 and 29 ° C, varies supply decreases. little with the season for the zones of Ouango Saö and the The directive of the European Communities on the quality of catchment by the Water distribution company (Sodéca). water intended for human consumption indicates a guideline For sites in the vicinity of the abattoir, the temperature is level of 400 μS/cm for conductivity. Mineralization of water higher during high water because of greater streams or small would therefore need to be increased during the treatment of releases. water, if one wants to reduce its aggressiveness. The Mpoko passes through a zone with strong vegetation The buffering capacity of these weakly mineralized waters is cover before Bangui, which is responsible for lower low, resulting in relatively low pH values. The lowest pH temperatures for the waters of the Mpoko and the Mpoko / values (5 <pH <5.4) are in the vicinity of the slaughterhouse, Ubangui confluence. due to the oxidation of Organic matter by the bacteria that The electrical conductivity is very low and therefore releases protons. The pH range between 5 and 9 (values characteristic of a very weakly mineralized water. It is recommended for fish life) is therefore suitable for aquatic generally weaker during the dry season because the runoff life. Fig 5: Evolution of turbidity at different sites Fig 6: Evolution of suspended solids content at different sites 44 European Journal of Biotechnology and Bioscience It is noted that the waters are more turbid during high water content: (a) all points, (b) except values for high water at the due to a higher suspended solids content due to high runoff. Aval Abattoir; Figure 7 Change in turbidity as a function of suspended solids Fig 7: Change in turbidity as a function of suspended solids content: (a) all points, (b) Figure 7 shows that there is a linear relationship between Incident light). Light scattering is related to the number and turbidity and suspended solids (TSS). If the value size of the particles. The slaughterhouse throws into the river, corresponding to the downstream waters near the the blood and the viscera of the killed animals, compounds slaughterhouse is eliminated, a line with a correlation which give more adsorbent particles and therefore responsible coefficient R² = 0.81 is obtained. The principle of measuring for a decrease in the value of the turbidity downstream of the turbidity is to measure the scattered light (Tyndall effect) at slaughterhouse. It can therefore be concluded that, apart from 860 nm laterally at 90 ° by particles under the effect of a light the waters near the slaughterhouse, the Ubangui particles have source (1 unit of NTU corresponds to 0.02% diffusion of the similar origins.