DETERMINATION OF SOME HEAVY METALS IN VEGETABLE AND SOIL SAMPLES IN WAZIRI IBRAHIM AND DIKKUMARI IRRIGATIONAL AREA OF DAMATURU, YOBE STATE.

The soils and leaves of Onions (Alium cepa), African spinach (Amaranthus hybridus) and Roselle (Hibiscus sabdariffa L.) were collected as randomly composite samples from two (2) different study location namely Waziri Ibrahim and Dikkumari irrigational farmers located at Damaturu Local Government Area of Yobe State. The samples were examined for heavy metal concentrations using Atomic Absorption Spectrophotometer (AAS) technique. Chromium (Cr), zinc (Zn), manganese (Mn), iron (Fe) of both soil and vegetable samples were detected at higher proportions than the permissible limits of WHO/FAO and EU for soils and plants. Exceptions were obtained for Cr in WI3 (Hibiscus sabdariffa L. from Waziri Ibrahim farm). Toxic heavy metals, such as, lead (Pb), cobalt (Co), cadmium (Cd) and copper (Cu) were not detected in both soil and vegetable samples. The Cr concentrations vary from 109.44 to 191.52 mg/kg among the soil samples and from 0.00 to 150.48 mg/kg among the vegetable samples. While there are relatively low transfer factors among the vegetable samples collected from both farms. The peak Cr (150.48 mg/kg) is observed in DI3 (Roselle from Dikkumaris farm), followed by 136.80 mg/kg in WI2 (African spinach from Waziri Ibrahim farm) while WI3 recorded 0.00 mg/kg Cr . Zn concentrations are higher in the vegetable samples than the soil with a slight deviation observed in DI1 (Onion from Dikkumari farm) and DI2 (African spinach from Dikkumari farm). The Zn concentrations range from 80.32 to 184.74 mg/kg for soil samples and from 40.16 to 722.88 mg/kg for vegetable samples. The Zn concentrations in this study exceed the permissible limits of 60 mg/kg (WHO/FAO, 2007) with exceptions in DI1 (Onions from Dikkumari).