ABSTRACT

The effects of oil spillage which occurred at Umuagu, Umuahia North Local Government Area of Abia State on June, 2002 on soil microorganisms and some economic plant species were studied. Three locations that represented three levels of oil pollution viz: Unpolluted, moderately polluted and highly polluted were mapped out for study. Soil samples were collected from these three locations at 2 depths 0 - 15cm and 15 - 30cm using soil auger. The soil was then used to raise six economic plant species {Tefferia occidentalis, Zea mays, Manilla! esculenta, Treculia africana, Penfaclethra macrophylla and Irvingia gabonensis). The following growth measurements: leaf number, leaf area, stem height and stem girth were taken weekly for 8 weeks. Microbiological and physico-chemical analyses of the soil were carried out. The result of microbiological analysis showed that total bacteria and total fungi count ranged from 6.25 x 106 to 3.45 x 106 cfiilg and 2.01 x 105 to 1.14 x 104 cfulg respectively. The least number of bacteria and fungi occurred in highly polluted soil samples. Seven bacteria genera {Lactobacillus sp, Klebsiella sp., Pseudomonas sp., Proteus sp., Streptococcus sp.. Bacillus sp. and Staphylococcus sp.) were isolated from unpolluted soil samples while four {Klebsiella sp., Pseudomonas sp., Proteustsp and Bacillus sp.) were isolated from polluted soil samples and were found to be hydrocarbon utilizers. The same types of fungi were found in all the soil samples with least number occurring within the polluted soil. Result of physico-chemical analysis of the soil showed that pH value ranged from 5.6 to 5.2 in the polluted soil and 5.7 to 5.8 in the unpolluted soil. Percentage organic matter ranged from 1.99 to 2.04 in the unpolluted soil and 2.52 to 3.99 in the polluted soils. There was a reduction in pM, effective Cation Exchange Capacity, Percentage Based Saturation,' Total Nitrogen and available Phosphorus of the polluted soils. Differences occurred in germination rale and growth rate of crops planted in the different soil samples. Analysis of variance showed that pollution level and soil depth had significant effect on Stem height growth, stem girth growth, leaf area growth and number of leaves produced by these crops at 5% probability level. Duncan’s Multiple Range Test showed that apart from Treculia africana, growth rate of economic crops on surface soil of polluted soil was poorer than those on sub-surface soil of polluted soil. The spillage affected the microbial, physico-chemical and growth rate of economic crops studied. Therefore, efforts should be made to reclaim the land alter oil spillage using bioremediation method.