Source apportionment, ecological and toxicological risk assessment of trace metals in agricultural soils of Wabane, South West Region, Cameroon

Abstract

Background

This study seeks to evaluate the origins, ecological implications, and ecotoxicological risks of trace metals using single and cumulative pollution indicators as well as mitigation strategies in the agricultural soils of Wabane, Cameroon.

Methods

The soil samples were analyzed by ICP-OES (Inductively Coupled Plasma-Optical Emission Spectrometry).

Results and Discussion

The agricultural soil samples exhibit high levels of Al₂O₃ and Fe₂O₃, which have high adsorption capacity for trace metals and are important carriers of trace metal migration and enrichment. The results highlight significant concentrations of Co, Cu, Cr, Ni, Hg, Mn, La, Sn and Zn above the geochemical threshold values, sourced from mixed provenance. Contamination assessment indicators: contamination factor (CF: 1–6), pollution load index (PLI: 0.02–1.23), and enrichment factor (EF: 0.21–604.80) suggest soil contamination and metallic pollution. The potential ecological risk indicators show minimal ecological effect of trace metals on the soil ecosystem. Toxic risk index (TRI: 0.36–7.60) and toxicity unit analysis (TUs: 0.004 to 0.96) indicates low toxicity, suggesting low toxicological effects of trace metals on the soil ecosystem. According to Pearson correlation matrix and principal component analysis, while Co, Cr, Cu, Ni, Zn and V were obtained from geogenic provenance, As, Cd, Pb, Hg and Mn originate from geogenic as well as anthropogenic input sources.

Conclusion

Lithogenic processes and anthropogenic practices contribute to contamination and metallic pollution of the soil ecosystem.

Recommendations

Concrete monitoring and mitigation measures (low metal cultivars, biochar, etc.) must be taken to reduce trace metal accumulation from point and non-point sources entering agricultural soils. This research acts as a baseline study to potential soil contamination and metal toxicity in soils within the vicinity of Mount Bamboutos.