Evaluation of Heavy Metals Contamination in Soils and Vegetables Grown in Selected Irrigation Sites in Katsina State, Nigeria

Abstract

Prolonged consumption of vegetables grown in soils contaminated with heavy metals poses significant health risks in humans and animals. This study, therefore, investigated the levels of some heavy metals of biological importance, such as mercury, cadmium, chromium, iron and lead in soils and selected vegetables grown in irrigation sites in Katsina State, Nigeria, using Atomic Absorption Spectrometry after HNO₃/H₂O₂ digestion. The findings revealed that the heavy metals were detected at varying levels, notably, Pb (0.98±0.00 mg/kg to 4.01±0.80 mg/kg) and Cd (0.001±0.00 mg/kg to 0.022±0.00 mg/kg) were present in all the soil samples at levels exceeding those recommended by Food and Agriculture Organization. The highest concentrations for Pb (1.81±0.03 mg/kg to 4.01±0.80 mg/kg) and Fe (8.01±1.24 mg/kg to 12.61±2.06 mg/kg) were observed in the vegetables grown in ‘Kofar Sauri’ irrigation site, while the lowest levels for Hg (0.001±0.0 mg/kg) and Cd (0.004±0.00 mg/kg to 0.021±0.00 mg/kg) were found in the vegetables grown around ‘Ajiwa’ dam site. Mercury (Hg) was however, not detected in most of the vegetable samples. Therefore, identification of contamination sources, sustainable agricultural practices and stringent regulatory measures are necessary to mitigate heavy metals contamination of foods and ensure food safety and healthy living.