Microbiological and Physicochemical Characteristics of Soil Contaminated With Used Petroleum Products in Umuahia, Abia State, Nigeria

Abstract

The discharge of used petroleum products from machines such as power generating sets, vehicles and motorcycles has become a major source of soil pollution around Umuahia metropolis. The objectives of this study were to assess the microbiological and physicochemical characteristics of soils contaminated with used petroleum products. A total of four (4) sampling sites (filling stations, vehicle mechanic workshop, motorcycle workshop and areas around power generating plants) were investigated. The total heterotrophic bacterial and fungal counts ranged from 1.6x107 to 1.9x108 CFU/g and 1.0x107 to 1.7x107 CFU/g respectively. The hydrocarbon utilizing bacterial and fungal counts ranged from 3.8x106 to 7.8x106 CFU/g and 1.0x106 to 1.4x106 CFU/g respectively. The bacterial isolates were Pseudomonas aeruginosa, Escherichia coli, Klebsiella spp, Staphylococcus aureus, Micrococcus spp, Bacillus spp, Citrobacter spp and Streptococcus spp. Fungal isolates included Aspergillus spp, Cladosporium spp, Mucor spp, Rhizopus spp and Geotricum spp. The total organic carbon concentration ranged from 5.20 to 16.74 mg/kg and 4.81 mg/kg for control. The contamination also affected other physicochemical parameters such as sulphate, nitrate and phosphate and ranged from 28.70 to 63.71 mg/kg, 21.73 to 53.79 mg/kg and 1.24 to 3.54 mg/kg respectively compared to the control sample, 11.93 mg/kg, 5.39 mg/kg and 0.64 mg/kg respectively. The contamination increased calcium, sodium, potassium, magnesium, iron and zinc concentrations compared to the control and caused a reduction in pH. These adverse conditions have impacted negatively on soils around the polluted site could affect nutrient cycles and consequently affect vegetation around the area.