Effects of Crude Oil on Some Bacteria and Mineral Constituents of Rhizosphere of Delonix Regia Hook.
ABSTRACT
Crude oil spill is hazardous to soil and subsequently affects food production. Certain plants however tolerate and/or improve the mineral deficiency imposed by crude oil.
Also, due to the ability of bacteria to degrade crude oil, plants that enhance the abundance of soil bacteria under pollution have been under investigation.
The effects of crude oil on the bacterial count and mineral constituents of soil rhizosphere of Delonixregia were investigated. The effects of D. regia on total bacterial count and mineral constituents were tested.
A total of 96 polythene bags were filled, each with 18 kg of soil. Four soil bags each containing a seedling of D. regia and four without seedlingwere polluted with 30 ml of crude oil.
This was repeated using 150 ml and 750 ml of crude oilwhile the control was not polluted. The experiment was set up in 3 replicates in a completely randomized design.
After one month, the soil bacterial count and mineral composition were analyzed using standard techniques. Bacterial analysis was repeated after the second and third month of pollution.
Some vegetative parameters were taken before and after pollution. The results of the 1st and 2nd bacterial counts revealed a significant (P<0.05) increase in soils treated with 750 ml of crude oil but a decrease in bacterial count of soil treated with 30 ml and 150 ml crude oil compared with the control.
INTRODUCTION
Crude oil is physically, chemically and biologically harmful to soil because it contains many toxic compounds in relatively high concentrations (Franco et al., 2004).
Soil contamination can result in soil degradation, bring great loss to agricultural production and pose threat to human health (Lijuan, 2012). Crude oil spill is a common event in Nigeria especially in the Niger Delta areas of the country.
Spills may arise from oil well drilling, production operations, transportation, refining, storage and marketing. It could also be from anthropogenic sources such as sabotage or accidental spills such as ruptured oil pipelines (Oberdorster and Cheek, 2000).
Presently there are eleven oil corporations operating about 159 oil wells in Niger Delta region of Nigeria. Record indicates that the Niger Delta region of Nigeria experiences on the average, 273 oil spills resulting to about 115,000 barrels of crude oil annually from 1983- 2005 making the region most vulnerable to oil spill than anywhere in the world (Agbogidi et al., 2009).
Some recent oil spill in Nigeria include Assa-Rumekpe pipeline at Elele Alumini in 2014, Amukpe trunk line at Amukpe in 2011, Nkpoku Bomu pipeline at Ekporo in 2014, Nun-river Kolo creek at Oporoma in 2013 (SPDC, 2014).
Oil spillage has immense impact on the ecosystem into which it is released. Contamination of soil arising from oil spills is one of the most limiting factors to soil fertility (Onwurah et al., 2007).
The legal problems related to compensation in terms of assigning monetary reward may bring serious controversy. Nigerian regulation of the oil industry is weak and rarely enforced, allowing in essence the industry to self-regulate.
The ecosystem especially the agricultural sectors are very much prone to the adverse effects of oil pollution, since there has been no concerned and effective effort on the part of the government, let alone the oil operators, to control this environmental problem.
REFERENCES
American Society for Microbiology (2013). Microbes and oil spills-FAQ. http://www.asm.org. accessed on 13th July, 2013.
Anderson, I. (2005). Niger river basin: A Vision for Sustainable Development. The World Bank, 131pp.
Anupama, M. and Padamas, P. (2009). Isolation of hydrocarbon degrading bacteria from soil contaminated with crude oil spill. Indian Journal of Experimental Biology, 47: 760-765.
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Atlas, R. M. (1978). Microbiology and petroleum pollutants. American Institute of Biological Sciences, 28(6): 236-245.
Benka-Cooker, M. O. and Ekundayo, J. A. (1995). Effects of oil spill on soil physicochemical properties of a spill site in the Niger Delta Nigeria. Environmental Monitoring Assessment, 36: 93-109.
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