HEAVY METALS CONTAMINATIONS IN SURFACE SOILS WITHIN BORI, RIVERS STATE, NIGERIA.
Heavy metal contaminations in surface soils within Bori were examined. The composite soil sample at 10 – 15cm depth was collected from each of the seven sampling locations including the control location using a stainless-steel hand auger. The soil samples were air-dried for 2 days, homogenized and sieved through a 2mm mesh to obtain uniform size. The soil samples were subjected to wet digestion method using nitric-perchloric acid. The digested samples were used for determination of concentrations of the heavy metals (Cd, Cr, Ni, Mn, Pb, Fe Cu and Zn) using the atomic absorption spectrophotometer (AAS). The mean concentrations of the heavy metals obtained ranged as follows: Pb (0.553 – 4.551 mg/kg), Cr (1.713 – 7.965 mg/kg), Cd (0.011 – 2.549 mg/kg), Mn (6.914 – 40.162 mg/kg), Ni (2.942 – 6.597 mg/kg), Zn (4.468 – 13.976 mg/kg) and Cu (1.90 – 11.503 mg/kg). The results were below the world average values except Fe (53.554 – 122.203mg/kg). The enrichment factor values ranged between 0.04 and 20.86 and showed low to moderate enrichment due to anthropogenic activities. The pollution load index (PLI) value was 1, the combined pollution index (CPI) values ranged between 0.39 and 1.73 and the metal pollution load index (MPL) value of 3.73 > 1 revealed pollution in urban surface soils of the study area. The high positive correlation result among the heavy metals in the sample soils of the study area suggested that they are of similar pollution sources. Based on the findings, the urban surface soils of the study area are contaminated with heavy metals. Therefore, there should be monitoring and environmental audit by relevant authorities to ensure adequate environmental quality of urban surface soils in the study area. Keywords: Heavy metals, contaminations, Bori, metal pollution load, combined pollution index.