Contamination, sources and risk assessments of metals in stream sediments of Pouma area, Pan-African Fold Belt, Southern Cameroon

The Pouma area is located within the Yaounde domain of the Pan-Africa Fold Belt in Cameroon. The objective of this study was to examine the geochemical distributions of elements in stream sediment so as to assess the trace metal contamination, sources of pollution and ecological risks assessment. Samples were obtained by panning and analysed by inductively coupled plasma-mass spectrometer. Stream sediments exhibit high content of Fe2O3 (0.48-8.86%), Mn (142-887 ppm), Th (12 to > 200 ppm), Zr (0.8-174 ppm), Sr (3-106 ppm), Au (18.9 to > 10,000 ppb), V (5-85 ppm), Y (9.62-101 ppm), rare earth elements (sigma REE = 181-3364 ppm), and depleted in the rest of elements. Factor analysis shows up to five factors accounting for 88.74% of cumulative variance. The pollution load index (PLI: 1.1-8.1), enrichment factor (EF: 0.01-1221), integrated nemerow pollution load index (NIPI: 3.57-25.93) and potential ecological risk index (RI: 3-7504) of silver (Ag), aluminum (Al), cadmium (Cd), copper (Cu), iron (Fe), mercury (Hg), nickel (Ni), lead (Pb), thorium (Th), uranium (U), yttrium (Y), zinc (Zn) and zirconium (Zr) indicate sediments contamination and metal pollution. Natural and metal input assessment reveals that the dominantly mafic lithology, quarrying and domestic activities as well as agricultural practices are the main source of metal contamination in Pouma area. The results of this study provide some valuable insights as it concerns the sediment assessment approach, which can be used to design and plan strategic sediment management programmes in the Pouma area.

Automated summary

The study aims to analyze the geochemical distributions of elements in stream sediment in the Pouma area of Cameroon to assess trace metal contamination, sources of pollution, and ecological risks. Samples were analyzed by inductively coupled plasma-mass spectrometer. The results show high contents of Fe2O3, Mn, Th, Zr, Sr, Au, V, Y, rare earth elements, and depletion of other elements in stream sediments. Factor analysis reveals five factors explaining 88.74% of cumulative variance. Assessment of pollution load index, enrichment factor, integrated nemerow pollution load index, and potential ecological risk index indicates sediment contamination and metal pollution, mainly from mafic lithology, quarrying, domestic activities, and agricultural practices. The findings of this study provide valuable insights for sediment management in the area.