BIOACCUMULATION OF SOME POTENTIALLY TOXIC ELEMENTS IN CROPS FROM FARMS AROUND GRANITE QUARRY SITES IN UMUNNEOCHI LGA, ABIA STATE

Mining results in clearing of vegetation and reduction of essential nutrients and organic matter of the soil, reduces biological activity, and decreases productivity of the soil. The aim to assess the compatibility of granite mining on agricultural (farmlands) on selected edible leaves in Umunneochi LGA, Abia State. Soil physicochemical and heavy metal properties of edible leaves were determined using standard procedures. The result for soil physicochemical properties shows that the mean of nitrogen of the soils varied from 0.07 -0.14 %. Organic matter ranged from 1.0 - 2.1%. The mean sodium varied from 0.114 - 0.126 cmolkg-1. The base saturation of the soils ranged from 78.1–90.8 % across the three sampling points and depths. Soil pH ranged from 4.5 (strongly acidic to 5.6 (moderately acidic) across the depths, indicating no significant different at P≥ 0.05. The effective cation exchange capacity (ECEC ) of the soils ranged from 5.1 - 8.5 cmolkg-1 across the three sampling points. Spinach leave had the highest concentration of Fe (92.4) and Pb (6.57), curry leave had 56.8 Fe and 1.89 Pb, ginger lilly had 12.86 Fe and 3.36 Pb. Fe levels in this study were comparatively higher in spinach (92.4mg/kg) and curry leave (59.8mg/kg) when compared with ginger lilly (12.86mg/kg). The cation exchange capacity values obtained in this study were below the value of 20 cmol/kg-1 reported as being suitable for crop production. The values of heavy metals concentration examined in the available edible leaves in the adjoining farmland were higher when compared with the heavy metals concentration from the soil. In conclusion, quarrying activity in the study area is degrading the environment around it thereby reducing the fertility of the soil. This study shows that the concentrations of heavy metals in soil decreased with increase in distance and are below toxic level. Periodic environmental impact assessment should be carried out to ascertain the changes in ecological status of arable lands within the quarrying site.