Speciation of selected heavy metals in some abandoned mining pond sediments of Barkin-ladi Lga, plateau state Nigeria

Abstract

Industrial and anthropogenic activities have resulted in high levels of heavy metal contents in some environmental aquifers such as mining abandoned ponds in like that in Barkin-ladi, thus creating imbalance in the biotic and abiotic regimes of the ecosystem. This study reveals the level and concentration of some selected heavy metals in the mining ponds which includes Cadmium (Cd), Chromium (Cr), Nickel (Ni) and lead (Pb). Sediment samples from these selected ponds were obtained and various fractions of the elements were produced by sequential extraction of the sediment samples using the modified Tessier et al. (1979) procedures. Concentrations of these heavy metals were determined using Microwave Plasma Atomic Emission Spectrophotometer (MP-AES), Agilent 4210. The results obtained showed that Lead and Cadmium were present in all the sites and fractions except for Cd were it was very low in all sites. Mean value were in the order of Pb> Cd > Ni > Cr with mean concentrations (mg/kg) of Cd = 0.023±0.003, Cr = 0.004±0.002, Ni = 0.008±0.002 Pb=0.136±0.007. Results also indicated that Cd and Cr are predominantly available in all fractions 1 – 9 and 3 respectively. Cd and Pb shows significant positive correlation, indicating likely existence either as similar specie or same point source. The presence of Lead in all sample sites shows that Lead is possibly associated with Tin, since study areas were all abandoned tin mining site. The research generally reveals that the heavy metals determined were in potentially available forms that could pose serious health problems to the agricultural and aquatic systems, especially Pb, Cd and Cr.