Analysis of Heavy Metal in Water used for Irrigation, Soil and Some Vegetables grown around Tin Mine Areas of Heipang District, Barkin-Ladi Local Government of Plateau State

Abstract

Vegetables growing in mining areas have become a serious food safety concern because of the high levels of heavy metals always associated with mining. In this study, water used for irrigation, soil, cabbage, green pepper and green beans grown in tin mine areas of Heipang District, Barkin-Ladi LGA of Plateau State were analyzed for lead, cadmium and zinc, using Atomic Absorption Spectrophotometer (AAS). The concentrations of the heavy metals in water, soil, vegetables were all in the order Pb, >> Cd > Zn. In the vegetables, the order was: Pb → cabbage > green beans > green pepper; Cd → green beans > cabbage > green pepper; Zn → cabbage > green pepper = green beans. The transfer factors for all the metals (heavy metal in plant / heavy metal in soil) ranged from 0.95 to 1.48. There were high levels of Pb and Cd in all the vegetables, which may be attributed to the metals in the water used for irrigation. Whilst the concentration of Zn in all the samples were lower than recommended limits, the levels of Pb and Cd in the water, soil and vegetables were higher than the WHO/FEPA standard recommended limits reported for vegetables. The Cd concentrations of the vegetables also exceeded the tolerance thresholds for animals and human beings and therefore consumption of vegetable from the area would endanger the health of the population.