Trace element levels and soil quality assessment in pineapple-cultivated soils of Awae, Central Cameroon

Abstract

Modern agricultural practices, especially the intensive use of pesticides and chemical fertilizers, significantly contribute to the accumulation of trace metal elements (TMEs) in soils. While some are essential for plant metabolism, others are toxic to living organisms. This study aims to assess the concentrations of TMEs and evaluate soil quality in the Awae area (Center, Cameroon). Soil samples were collected from cultivated plots, fallow lands, and forested areas and analyzed for their physicochemical properties, TME concentrations, and pollution levels using geochemical indices, including the enrichment factor (EF), geo-accumulation index (Igeo), contamination factor (CF), and pollution load index (PLI). The soils are predominantly clayey (44.33 to 55.29%), strongly acidic (pH 3.97 to 4.68), and rich in organic matter (5.25 to 6.27%). Mean TME concentrations (ppm) across the different land uses decrease in the following order: Al > V > Cr > Cu > Sc > Pb > As > Mo > Cd. Cadmium, scandium, vanadium, and arsenic are the most concerning elements, with concentrations exceeding the upper continental crust (UCC) background values. The Igeo index reveals high contamination levels for Cd (3.92–4.08), while the CF indicates moderate contamination for other elements (1.27–1.80). Correlation matrix analysis highlights associations among certain metals, suggesting common sources and mobility influenced by soil acidity. Overall, agriculture significantly influences TME concentrations and dynamics in soils. Promoting organic fertilizers and implementing regular monitoring of trace metal levels are essential to ensure sustainable agriculture and protect soil quality against environmental and health risks.