Application of Multiple Ecological Risk Indices for the Assessment of Heavy Metal Pollution in Soils in Major Mechanic Villages in Abuja, Nigeria

Heavy metal contamination has become a serious environmental problem due to their negative effects on humans, organisms, soil quality, underground water and ecosystem. This research was targeted at the use of multiple ecological risk indices approach in assessing the ecological risk associated with heavy metal contamination in soils in some mechanic villages in Abuja, central Nigeria. To achieve this set objective, four pollution indices models namely: contamination factor (Cf), ecological risk factor (Er), degree of contamination (CD) and potential ecological risk index (PERI) were explored. Fifteen soil samples were randomly collected with a hand dug auger to a depth range of 0-15 cm with five sample points from each of the three investigated mechanic villages. A control sample was also collected from a distance of 100 km where neither commercial nor industrial activities take place. The sampled soils were further subjected to standard chemical analysis. The automated Atomic Absorption Spectrophotometer (AAS) was used for this purpose. The results of the chemical analysis revealed that concentrations of heavy metals in Apo, Kugbo and Zuba mechanic villages followed a trend of Cu > Zn > Cr > Fe > Pb > Ni > Cd; Zn > Cu > Cr > Ni > Fe > Pb > Cd and Zn > Cr > Cu > Fe > Pb > Ni > Cd respectively. The multiple ecological risk indices models explored in the study showed various ecological risk level associated with heavy metal contamination of soils from the investigated sites with classes ranging from low to very high ecological risks. This could be traceable to anthropogenic activities like indiscriminate discharge of heavy metal containing waste in soil and poor waste management practice in the mechanic villages. This calls for urgent measure in curtailing indiscriminate waste discharge and the introduction of environmental friendly waste management in the mechanic villages so as to avert epidemics and environmental degradation due to heavy metal pollution.