Evaluation of Heavy Metal Contamination in Soils and Vegetable Crops from Agbara Industrial Zone, Ogun State, Nigeria
DOI:
https://doi.org/10.67601/njbls.v3i2b.71Keywords:
Cadmium (Cd), Chromium (Cr), Copper (Cu), Iron (Fe), Nickel (Ni), Lead (Pb), Zinc (Zn), Contamination, Food safetyAbstract
Heavy metal contamination of agricultural soils can affect the quality of crops grown in industrial areas. This study evaluated the concentrations of cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), nickel (Ni), lead (Pb), and zinc (Zn) in agricultural soils and vegetables from the Agbara Industrial Zone, Ogun State, Nigeria. A cross-sectional field-based design was used, and samples were collected from selected vegetable farms. The study analysed a total number of forty-five (45) samples, comprising farm soil and three vegetable types: spinach (Spinacia oleracea), tomato (Solanum lycopersicum), and okra (Abelmoschus esculentus). Samples were prepared by acid digestion, using USEPA Method 3050B for soil and wet acid digestion for vegetable samples, and the metals were determined using atomic absorption spectrophotometry. Pearson correlation analysis was used to examine relationships among the analysed metals, with significance tested at the 0.05 and 0.01 levels. The results showed that soil generally had higher concentrations of Fe, Zn, Cu, Cd, Pb, and Cr than the vegetables, while Ni was higher in spinach than in soil. Spinach recorded the highest concentrations of Cd (0.752 mg/kg), Ni (3.651 mg/kg), and Pb (0.526 mg/kg). Cd exceeded the reference value of 0.10 mg/kg in all vegetables, while Pb exceeded 0.30 mg/kg in tomato and spinach. Several strong positive correlations were observed among the metals. The findings provide baseline information on heavy metal concentrations in agricultural soils and vegetables within the study area.
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