Heavy Metals and Contamination Status in Surface Soil within and Distances Away From Bauchi Main Abattoir, Bauchi State, Nigeria

Activities in abattoirs and direct release of its waste into the environment are on the increase due to the high protein demand and hence there is need for proper assessment of abattoir soil with the aim of evaluating its degree of contamination. The objective of this paper is to evaluate the levels of selected heavy metals and contamination status in surface soil within and distances of 0-40 cm, 40-80 cm, 80-120 cm and a control (60 cm) away from Bauchi main abattoir, Bauchi State, Nigeria using Atomic Absorption Spectrophotometry. The observed ranges (mg/kg) are: cadmium (14.90-22.96), cobalt (9.13-11.96), copper (1.13-13.98), chromium (2.93-6.92), iron (556-739),manganese (42.43-71.43), nickel (5.97-11.96),lead (8.00 -30.30) and zinc (0.66-2.97 ) in the studied area, while the control values (mg/kg) are: cadmium (8.80), cobalt (5.96), copper (0.97), chromium (0.96), iron(34.60), manganese (21.33), nickel (2.96), lead (7.97) and zinc(0.96). The study indicated that, the levels of heavy metals in the studied area decreased as the distance increases. The enrichment factor (EF) follows the order: Mn ˃ Cu˃ Cr ˃ Ni ˃ Pb ˃ Cd ˃ Zn ˃ Co (0 – 40 cm), Co ˃ Mn ˃ Zn ˃ Cr ˃ Cu ˃Ni ˃ Cd ˃ Pb (40 -80 cm) while at 80 -120 cm the order was: Cr ˃ Mn ˃ Co ˃ Pb ˃ Ni ˃ Cd ˃ Cu ˃ Zn. The order of the contamination factor (CF) was: Cd ˃ Co ˃ Cu ˃ Pb ˃ Ni ˃ Fe ˃ Mn ˃ Cr ˃ Zn at the studied abattoir, while at the control location, the CF follows the order : Cd ˃ Co ˃ Pb ˃ Ni ˃ Mn ˃ Cu ˃ Cr ˃ Fe ˃ Zn. Based on the indices of metal pollution, the soil are classified as very slight contamination to severe pollution. The I-geo index spread from practically uncontaminated to moderately contaminated, the enrichment factor at all distances in all the abattoir soils studied were greater than 1.00 indicating that these heavy metals are from anthropogenic source, while the pollution load index (PLI) in all the locations were found to range from 1.06 – 2.27. The PLI values in all the studied soils are within moderately polluted (1 < PLI < 2) category. The operations of Bauchi main abattoir are therefore not environmentally friendly based on the levels of iron and cadmium and this can pose health and environmental threats to the residents.