Impact of Abattoir Effluents on the pH, Organic Matter, Heavy Metal Levels and Microbial Composition of Surrounding Soils in Calabar Municipality

Abstract

This study examined the impact of abattoir activities on the heavy metal levels and microbial composition in surrounding soils receiving abattoir effluents within Calabar Metropolis. A total of nine composite soil samples were gotten from three locations: Atimbo, Ikot Eneobong and Nasarawa abattoir and environs. The results obtained revealed that the uncontaminated sites (control) had a strongly acidic pH while the abattoir contaminated soils were slightly acidic to slightly alkaline in reaction. Soil organic carbon content was low (< 1.5%) at the control site while the abattoir contaminated sites were high (> 2.0%). The heavy metal levels were highest at the point of direct discharge of abattoir effluents (Cu: 7.27 mg/Kg; Cd: 0.49 mg/Kg; Zn: 47.23 mg/Kg; Pb: 2.62 mg/Kg and Fe: 1071.69 mg/Kg) followed by the surrounding soils (Cu: 6.60 mg/Kg; Cd: 0.40 mg/Kg; Zn: 30.86 mg/Kg; Pb: 1.81 mg/Kg and Fe:871.76 mg/Kg) and the least values were obtained from the control (Cu: 5.45 mg/Kg; Cd: 0.30 mg/Kg; Zn: 16.30 mg/Kg; Pb: 1.60 mg/Kg and Fe 586.25 mg/Kg).  Bacterial communities such as: Escherichia coli, Bacillus spp, Staphylococcus spp, Klebsiella pneumoniae and Staphycoccus epidermis were isolated from the abattoir effluents contaminated sites. Fungal isolates from the abattoir effluents contaminated soils include: Aspergillus spp, Fusarium sporotrichiodes, Penicillium erichimultum, Absidia spp. and Mucor pusillus. Generally, bacteria and fungi population and diversity were higher in abattoir effluents contaminated soils than the control. The increase in heavy metals levels and the presence of numerous and diverse communities of organisms indicated possible pollution. This calls for concern, as increase levels of heavy metals and invading pathogenic organisms can pollute water bodies as well as affect plant, human and animal health. Therefore, abattoir effluents should be channeled into septic tanks where it can be properly treated before being discharged into the soil environment.