Determination of some heavy metals in soil and vegetable samples from Gonglung agricultural location of Jere Local Government Area of Borno State, Nigeria

The vegetable samples of (Tomatoes, Onion, Spinach and lettuce) and the soil samples were all collected at Gonglung Agricultural Locations. The soil samples were collected at three different depths of 0-5 cm, 5-10 cm and 10-15 cm respectively. The concentrations of some of the heavy metals Cr, Mn, Co, Ni, Cu, Zn and Pb were found to be lower than the threshold limit of 100mg/kg, 0.3 mg/kg, 0.2 mg/kg, 10 mg/kg, 10 mg/kg, 1.5 mg/kg, and 2 mg/kg. However, Fe and Cd recorded a higher concentration value than the threshold limit of 0.3 mg/kg and 0.02 mg/kg in a soil samples collected at a depth of 0-5 cm, 5-10 cm and 10-15cm. The concentration of the heavy metals Fe, Co, Ni, Cu, Zn in vegetable samples (Tomatoes, Onion, Spinach and lettuce) exceeded the maximum threshold limits of 0.3 mg/kg, 0.02 mg/kg, 0.1 mg/kg, 10 mg/kg and 1.5 mg/kg set by FAO/WHO. Also, the concentrations of Cd both 0.06 mg/kg in (Tomato and Onion) and Mn 0.04 mg/kg (Onion) were found to be higher than the maximum limits of 0.02 mg/kg and 0.04 mg/kg set by FAO/WHO. However, Cr and Pb in all the four vegetable samples were found to be lower than the threshold limit of 0.2 mg/kg and 0.1 mg/kg.