Abstract

The use of industrial and domestic wastewaters for irrigation on vegetable gardens is a public health concern. Using atomic absorption spectrophotometry (AAS), concentrations of Cr, Co, Cu, Ni, Pb and Zn were determined in four different vegetables, including,spinach, okra, onions and tomatoes, grown in effluent irrigated fields at Sharada, Kwakwachi and Jakara in the Kano metropolis, Nigeria. Similar vegetable samples from another irrigated field at Thomas Dam, in the remote part of Kano, were used as control. Samples were collected during dry and rainy seasons. The mean level of metals obtained ranged widely from 0.28 mg/Kg Cr to 18.89 mg/Kg Zn. Samples from Jakara garden indicated highest mean levels of Co (1.14±0.17 mg/Kg), Cu (7.50±1.08 mg/Kg), Zn (18.89±1.93 mg/Kg) and Cr (0.85±0.10 mg/Kg) while those from Sharada indicated highest levels of Ni (2.02±0.35 mg/Kg) and Pb (1.60±0.53 mg/Kg). Comparison of results with the control showed significant levels (p<0.05) of all the metals analyzed in the vegetable samples obtained from the effluent irrigated gardens. However, the levels were within the National Agency for Food and Drug Administration and Control (NAFDAC) tolerable limits for metals in fresh vegetables.

Key words: Industrial effluents, irrigation, vegetables, metals, atomic absorption spectrophotometry (AAS), Kano.