Evaluation of the Physico-Chemical Parameters of the Sediments of the Tsieme River in Brazzaville (Republic of Congo)

Population growth, accompanied by rapid urbanization, is the cause of many disturbances in natural environments. The presence of physical and/or chemical contaminants in sediments causes toxic effects in aquatic environments. This work aims to determine the physicochemical parameters of the sediments of the Tsiémé River in Brazzaville during the dry and rainy seasons. Four (04) sediment samples were taken per season and analyzed by potentiometric, X-ray diffractometric and Robinson methods. The results obtained show that quartz is the only mineral species detected. The particle size distribution of the sediments shows particles of different sizes in the order of coarse sand > fine sand > coarse silt > fine silt. The sediments of the Tsiémé River are moderately acidic with pH values varying between 5.75 and 6.69 in the dry season and between 6.38 and 7.13 in the rainy season. The low values of electrical conductivity ranging from 18 to 173 μs/cm in the dry season and from 13 to 86 μs/cm in the rainy season characterize the low mineralization of the sediments. The percentage of total nitrogen varies from 0.004 to 0.006% in the dry season and from 0.00 to 0.005% in the rainy season. Similarly, the total phosphorus rate fluctuates between 0.007 and 0.07% and from 0.06 to 0.1% in the dry and rainy seasons. The organic matter contents vary between 0.248 to 3,549% and 0.038 to 0.114% in the dry and rainy season. These results indicate the absence of mineral and organic pollution of the sediments. Thus, the sediments of the Tsiémé River do not present imminent risks from a physicochemical point of view.