Assessment of Sediment Contamination by Heavy Metals in the Water of Mgoua Catchment in the Industrial Zone of Douala (Cameroon)

Abstract

Aquatic ecosystems are increasingly affected by human activities, notably urban sewage and industrial effluent discharges, particularly in rivers. This study assesses heavy metals contamination of sediments of the Mgoua River in Douala, Cameroon. The Geoaccumulation Index (Igeo), the Contamination Factor (FC), the Sediment Pollution Index (SPI), the Enrichment Factor (EF) and the Pollution Load Index (PLI) were used to assess the contamination risk. The mean concentration of Ti, V, Cr, Co, Ni, Cu, As, Cd, Zn, Pb, U, Rb, Sr, Y, Zr, Mo, Mn, Fe, Cs and Ba in sediments was 12601.08, 111.96, 151.93, 9.47, 65.43, 161.81, 7.55, 2.27, 419.30, 248.30, 49.30, 12.65, 89.50, 39.69, 3017.52, 5.95, 313.26, 39667.32, 0.97 and 243.19 µg/l, respectively. Heavy metals concentrations in sediments creased in the following order: U < Cs < Cd < Mo < As < Co < Rb < Y < Ni < Sr < V < Cr < Cu < Ba < Pb < Mn < Zn < Ti < Fe. The Igeo, CF and EF indicate a polymetallic contamination dominated by Cu, Cd and Pb being the most important in all studied sites. The value of SPI varied between 10.95 and 37.84, suggesting that the sediments are moderately to highly polluted, with PLI higher than 1. These indices reveal that the sediments of Mgoua river catchment were polluted with most of the heavy metals. The high concentrations of some of the metals were due to anthropogenic sources particularly the discharge of untreated industrial wastes in to watercourses. This study can therefore be used as a reference to monitor the quality of sediments of the Mgoua river.