ABSTRACT
Heavy metal contamination of food crops through irrigation is a major concern due to the potential risk involved. This study was designed to investigate the contamination of food crops grown through irrigation along River Kubanni and Galma, Zaria, with heavy metals (Pb, Cu, Mn, Cd, Cr and Fe). To achieve this, Pb, Cu, Mn, Cd, Cr and Fe concentrations in water and food crops and the transfer factor of these metals from water to food crops were determined. Samples of food crops (maize, spinach, lettuce and bitter leaf) and corresponding irrigating water were collected, water sample from Zaria water works was also collected as a control and metals assessed using Atomic Absorption Spectrophotometer. The results showed the presence Cu, Cr, Pb, Cd and Fe in all the food crops although significantly higher in lettuce compared to other food crops beyond the limits of International standard FAO/WHO. Water samples revealed low concentration of Cu and Mn, with values below the International permissible limits for water quality, WHO with exception of Pb, Cr, Fe and Cd (at some sites). Metal transfer factors from water to food crops are found significant in leafy vegetable (lettuce, spinach and bitter leaf) than maize. From this result, it was also observed that other than contamination of food crops by irrigation water, other sources of metal deposit could be responsible. Generally, heavy metal contamination of food crops grown along River Kubanni and Galma, Zaria posed a great health risk to the local population through consumption of the food crops especially lettuce.