Assessment of traces metals in sediment from Ebolowa Municipal Lake basin (central-africa): potential risk and provenance

Abstract

This study focused on assessing contamination levels of heavy metal elements (Cr, Co, Ni, Zn, Cu, Mo, Cd, and Pb) in surface sediments for the Ebolowa Municipal Lake (EML) basin in Southern Cameroon and identifying possible pollution sources. Twenty-one samples from the EML and its tributaries (Mfoumou and Bengo'o) were subjected to geochemical analysis by inductively coupled plasma-mass spectrometry (ICP-MS). The results obtained from these analyses allowed us to calculate the Contamination factor (CF), enrichment factor (EF), geo-accumulation index (Igeo), Potential Ecological Risk Factor (Er), Pollution Load Index (PLI), and Potentiel Ecological Risk Index (RI). Multivariate statistics completed these analyses. The concentrations in mg/kg are as follows: Cr (96.46) > Zn (55.94) > Cu(34.01) > Ni(30.77) > Co(16.14) > Pb(10.58) > Mo (0.61) > Cd (0.14). However, these concentrations are higher in the sites subjected to the most anthropogenic pressure (EML and Mfoumou). The pollution indexes are between: 0.29 ≤ CF ≤ 2.76, -28.10 ≤ Igeo≤0.13, 0.14 ≤ EF ≤ 2.19. PLI values ˂ 1 in all sites. Er has high values for Cd (21.43–42.85) and low values for the other elements. RI ˂ 100 values for all elements and on all sites. Pearson's correlation matrix and the Hierarchical Classification Ascending (HCA) illustrate two sources of inputs. The spatial distribution of TME seems to be impacted by autochthonous inputs of domestic effluents and parameters such as particle size and organic matter content. The pollution index values illustrate low to moderate contamination and pollution in Cr, Ni, Co, Cd, and Cu. The Er values illustrate a moderate ecological risk for Cd. The RI values indicate a low ecological risk for all sites. High values are mainly associated with poor domestic waste management, non-compliant automotive buildings and agricultural activities.