CHAPTER ONE
1.0 INTRODUCTION
Soil contamination is one of the major environmental problems facing the world today.
Contamination of soil by hydrocarbons (mostly petroleum hydrocarbons) is becoming
prevalent worldwide (Njoku et al., 2008). This is probably due to heavy dependence on
petroleum as a major source of energy throughout the world, rapid industrialization,
population growth and complete disregard for the environmental health. In Nigeria, oil
pollution problems have been prevalent since the commencement of oil exploration and
development of the petroleum industry (Okohet al., 2001). Release of hydrocarbons into the
environment whether accidentally or due to human activities is a main cause of water and soil
pollution (Holligeret al., 1997). These hydrocarbon pollutants usually cause disruptions of
natural equilibrium between the living species and their natural environment. Hydrocarbon
components have been known to belong to the family of carcinogens and neurotoxic organic
pollutants (Das and Chandran, 2010). The amount of natural crude oil seepage was estimated
to be 600000 metric tons per year with a range of uncertainty of 200,000 metric tons per year
(Kvenvolden and Cooper, 2003). Soil contamination with hydrocarbons causes extensive
damage of body system since accumulation of pollutants in animals and plant tissue may
cause death or mutations (Sheetal, 2012). These oil spills can even cause damage to the sea
and shoreline organisms (Rodríguez-Martínez,2006). Other sources of contamination include
service stations, garages, scrap yard, waste treatment plants, saw mills, etc. Hydrocarbons
differ in their susceptibility to microbial attack and can be generally 5 ranked as follows:
linear alkanes > branched alkanes > small aromatics > cyclic alkanes (Rosenberg and Ron,
1996). Some compounds, such as the high molecular weight polycyclic aromatic
hydrocarbons (PAHs), may not be degraded at all. Between 1976 and 1996, a total of 4,647
oil spill incidents were recorded in Nigeria which resulted in the spill of approximately 2.3
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