Bioaccumulation of Heavy Metals Concentration in Some Selected Cereals Grown Near Illegal Mine Sites at Poyentanga in Wa of the Upper West Region, Ghana

Abstract

The contamination of cereals by heavy metals due to illegal mining activities in most farming communities has been a major challenge to food production in Ghana. The research is thus to examine bio-accumulation of heavy metals (Cadmium (Cd), Arsenic (As), Iron (Fe), Lead (Pd) and Zinc (Zn)) concentration in Maize and Millet grown near illegal mining sites at Poyentanga. The study area was divided into five farming zones (farm 1, 2, 3, 4 and 5) and soil and crop samples were taken from each of the zones to the laboratory for analysis using the Atomic Absorption Spectrometer and the results compared to World Health Organization (WHO) permissible limits. The results indicated presence of the selected heavy metals in the cereals and soils sampled from the community. Cd, Pb and Fe concentrations in the cereals were found to be above the WHO permissible limits whereas As and Zn concentrations were below. The soil concentrations of all the five heavy metals were extremely below the WHO permissible limits. It was also observed that farms near the mining sites have higher concentrations with the concentration in the maize being lower than that of Millet. The contamination levels in both cereals are as follows: Zn < As < Fe < Pb < Cd. The bioaccumulation ratio indicated that Cd, As and Pb levels were higher in Millet whereas Fe and Zn were highest in the Maize. These results therefore show that the consumption of these cereals for a very long time could have adverse health effect on the community and an indication that activities of illegal mining could thus affect the quality and safety of food produced in many farming communities. The research was concluded with recommendations to improve agricultural activities in such communities.