Level of heavy metals in vegetables grown on irrigated farmland

Levels of Cd, Cu, Pb, Zn, Fe and Ni were determined in vegetables irrigated with stream water and also in control vegetables watered from a different source. Occurrence of these metals in stream water, sediments and farmland soil were also investigated. The mean concentration of metals in the stream water are (in mg/l) 0.5 0.45, 0.06, 1.80, 2.25 and 0.35 for Cd, Pb, Fe and Ni respectively. These values were however, higher for Cd, Pb, Fe, and Ni than values recommended by NAFDAC for portable water. This could be detrimental to the health of the aquatic ecosystem and the community that uses the water for domestic purpose without treatment. These metals were detected in soil, sediment vegetables and control vegetables. There were slight differences in the vegetable samples with the irrigated vegetable samples accumulating the metals more than the control samples. This indicates a possible contribution from the stream water. However the levels in vegetables are quite below the phytotoxic levels and no imminent danger is posed to consumers.