AbstractThe objective of the present study was to assess the status of surface sediments from Funa River. Sediment samples were characterized for physicochemical parameters, including grain size, organic matter and toxic metals. The result revealed high metal concentrations in river sediments, reaching values of 154.19, 186.00, 1105.34, 3.69, 548.02 and 5.45 mg/kg for Cr, Cu, Zn, Cd, Pb and Hg, respectively. A strong correlation was observed between analysed metals and organic matter suggesting that these contaminants could have originated from common sources with a similar transport pathway. Based on the Sediment Quality Guidelines for the Protection of Aquatic Life, Funa River is considered as highly polluted with toxic metals indicating the potential environmental and human health risk. The results of this research represent a useful tool to assess the sediment quality of urban river receiving system which can be applied to similar environment.
Water resource contamination is still a major concern in several regions of developing countries especially in sub-Saharan countries in which polluted waters pose serious risks to human health and the environment. The seasonal variation of the physicochemical parameters including pH, electrical conductivity (EC), dissolved oxygen (O2), dissolved organic carbon (DOC), total organic carbon (TOC), and trace metals were assessed in water samples collected from wells (n=3) and two rivers which were the River Lukemi (RLK, n=3) and River Luini (RLN, n=2) located in the City of Kikwit (Province of Kwilu, Democratic Republic of the Congo). Samples were collected during the dry and wet seasons. The concentration of trace metals (Cr, Mn, Co, Ni, Cu, Zn, As, Mo, Ag, Cd, Sn, Sb, and Pb) in water was measured using Inductively Coupled Plasma Mass Spectrometry (ICP-MS), and soluble ions (Na+, K+, NH4+, SO42-, NO3-, and Cl-) analysis was performed using Ion Chromatography. The results indicate the seasonal difference in the physicochemical composition of water e.g., the pH was lower in the wet compared to the dry season. pH values during the wet season ranged from 4.12 to 5.60 in wells and from 5.55 to 6.31 in rivers while the dry season values ranged from 6.27 to 6.98 in wells and from 7.09 to 7.44 in rivers. The concentrations of soluble ions and other physicochemical parameters (O2, DOC, and TOC) also varied with the seasons, being higher in the wet and lower in the dry season. With the exception of Mn, the average concentrations of other trace metals measured in water samples from wells and rivers met the World Health Organization (WHO) guidelines for drinking/domestic water quality. Mn concentration in water samples analysed ranged between 634 and 812 and 1352 to 1741 µg L-1 during the dry and wet seasons, respectively. These results imply that the high concentration of Mn in the water samples may be explained by the geological origin and result of natural weathering processes. In general, according to the parameters analysed, the water samples taken from the sites studied in both seasons appear to meet drinking water standards according to the WHO guidelines but with the two exceptions of the pH and Mn. This study is important for the present situation and can be applied in similar environmental compartments in the future to assess the availability of safe drinking water in developing countries.
