Zakari Mohammed - Department of Pure and Applied Chemistry, University of Maiduguri, P.M.B ۱۰۶۹, Maiduguri, Borno State, Nigeria
Mohammed Shettima - Department of Pure and Applied Chemistry, University of Maiduguri, P.M.B ۱۰۶۹, Maiduguri, Borno State, Nigeria
Haruna Wayar - Department of Chemistry, University of Maiduguri
Ayuba Maina - Department of Pure and Applied Chemistry, University of Maiduguri, P.M.B ۱۰۶۹, Maiduguri, Borno State, Nigeria
Joseph Akan - Department of Pure and Applied Chemistry, University of Maiduguri

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 ۰-۵ cm, ۵-۱۰ cm and ۱۰-۱۵ 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 ۱۰۰mg/kg, ۰.۳ mg/kg, ۰.۲ mg/kg, ۱۰ mg/kg, ۱۰ mg/kg, ۱.۵ mg/kg, and ۲ mg/kg. However, Fe and Cd recorded a higher concentration value than the threshold limit of ۰.۳ mg/kg and ۰.۰۲ mg/kg in a soil samples collected at a depth of ۰-۵ cm, ۵-۱۰ cm and ۱۰-۱۵cm. 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 ۰.۳ mg/kg, ۰.۰۲ mg/kg, ۰.۱ mg/kg, ۱۰ mg/kg and ۱.۵ mg/kg set by FAO/WHO. Also, the concentrations of Cd both ۰.۰۶ mg/kg in (Tomato and Onion) and Mn ۰.۰۴ mg/kg (Onion) were found to be higher than the maximum limits of ۰.۰۲ mg/kg and ۰.۰۴ 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 ۰.۲ mg/kg and ۰.۱ mg/kg.

Zn = Zinc, Cr = Chromium, Mn = Manganese