CHAPTER ONE

INTRODUCTION

1.1       Background of the Study

In the current industrial society, using petroleum as a primary source of energy and for petrochemical by-products is inevitable (Bierkens and Geerts, 2014), but for some specific places these activities pose the major sources of soil and water pollution as well (Hentati et al., 2013). According to Macci et al. (2013), industrialization during the past decades caused an ever-increasing reliance on petrochemicals, and as a consequence, many sites have been significantly contaminated with petroleum and the petroleum by-products (Jesus et al., 2015 and Gennadiev et al., 2015). This is especially more serious around the petroleum and petrochemical complexes and refineries in the countries producing these materials and generally the overall industrialized regions.

Crude oil and its products have aroused much interest in recent years among ecologists and environmentalists in Nigeria and other parts of the world owing to the havoc wreaked on living organisms as well as arable lands by spilled petroleum. Even though crude petroleum since its discovery as an energy source has greatly increased the rate of civilization, the ever-growing ravages it wreaks on the ecosystem underscore its role as a potential environmental pollutant. It has been shown to negatively affect both the biotic and abiotic components of the ecosystem (Chaineau et al., 2000; Wyszkowska et al., 2001; Adoki and Orugbani, 2007). Various activities in petroleum exploration, exploitation, storage and transportation have led to spillage of oil to the environment.

Petroleum spills caused some environmental problems during the early 20th century when ocean transport of large volumes, of crude oil started (Bourne, 1968). Efforts to combat the increasing number of oil spills and intentional oil discharges on the sea continued during the 1950s.The wreck of the Torrey Canyon off the coast of England in 1967 produced global concern about the consequences of large–scale oil spills in the marine environment (Eze, 2010).

In Nigeria for instance, oil spill is a major environmental problem. According to information from the Department of Surveying and Geoinformatics, University of Lagos, between 1976 and 1996, Nigeria recorded a total of 4,835 oil spill incidents which resulted in the loss of 1,896,960 barrels of oil to the environment (Eze, 2010). In 1998, still in Nigeria, 40,000 barrels of oil from Mobil platform off the Akwa Ibom coast were spilt into the environment causing serious damage to the coastal environment (Eze, 2010). Oil spillage along the Nigerian coast has caused much destruction of flora, fauna and resort centers, pollution of drinking water as well as destruction of human lives and property. Factors responsible for oil spillage in Nigeria include corrosion of oil pipelines and storage tanks (leading to leakage), sabotage (pipeline vandalization) and inadequate care during oil production operations (Eze, 2010).

According to the EPA (US Environmental Protection Agency) the very hazardous chemicals like benzene, toluene, ethylbenzene, xylenes, and naphthalene are included in the petroleum hydrocarbons (Germaine et al., 2015). These pollutants can affect soil physical characteristics like soil texture and structural status, compaction, saturated hydraulic conductivity, and penetration resistance (Hreniuc et al., 2015). When released on the surface soil, petroleum hydrocarbons, with a specific physico-chemical characteristics (Zahed et al., 2010) pushes soil toward a condition undesirable for proper and sustainable growth of plant and rhizosphere organisms activity (Masakorala et al., 2014).

Physicochemical and geophysical assays have been widely employed and are proven to be effective in the characterization of petroleum polluted sites. The physical and chemical properties of the soil undergo major changes, which affects the growth of plants after soil pollution by oil (Udo and Fayemi, 1975). Some important soil factors which are affected include soil water potential, soil atmosphere, exchangeable Fe and Mn, total nitrogen, available phosphorus and sulphur status in the soil (Udo and Fayemi, 1975). Abii and Nwosu (2009) while studying two oil spill affected areas: Ogali and Agonchia in 2009reported a significant decrease in the Ca, K, P, (CEC) as well as a significant increase in the sand fraction and Na contents of the oil spill affected soils when compared with the non-affected soil.

Geophysical technologies have been used for decades in industries, principally the petroleum and mining industries, for their ability to describe geological structures deep within the earth’s crust (Atekwana et al., 2000). This proven track record has been easily transferred to the characterization of hazardous waste sites. Geophysical technologies, such as electrical conductivity or resistivity, Ground Penetrating radar, Electromagnetometry, have been in wide use already at hazardous waste sites to locate buried drums and structures that often constitute source areas. The use of geophysical technologies is rapidly expanding to other applications in hazardous site characterization, including the direct detection of aqueous and non-aqueous phase contamination.

1.2       Aim and Objectives of the Study

The aim of this study is to examine the extent of pollution using physicochemical and geophysical techniques while the specific objectives will be to:

i.    Characterize the petroleum polluted site using physicochemical methods

ii.   Characterize the petroleum polluted site using geophysical techniques

iii.  determine statistically the level of contamination in the polluted site using geochemical indices

iv.  Make recommendations based on this finding

1.3       Statement of the Problem

Crude oil regularly escapes into the environment during extraction, transportation, and during storage. The final destination of many of these contaminants will be the terrestrial and aquatic ecosystems. In Nigeria alone, the Nigerian National Petroleum Corporation places the quantity of petroleum jettisoned into the environment yearly at 2,300 cubic metres with an average of 300 individual spills annually. This occurs due to a number of causes, including: corrosion of pipelines and tankers (accounting for 50% of all spills), sabotage (28%), and oil production operations (21%), with 1% of the spills attributed to inadequate or non-functional production equipment. Petroleum pollution has a major impact on the ecosystem into which it is released and may constitute ecocide. Immense tracts of agricultural lands have been destroyed. An estimated 5 to 10% of Nigerian agricultural lands have been wiped out either by settlement or oil (Nwilo and Badejo, 2001).

It is pathetic that a once rich agricultural soil is being impoverished and made useless by petroleum spillage. The potential contamination of our diverse ecosystems by petroleum products has been a primary driving force behind this studyin the characterization of petroleum polluted sites using physicochemical and geophysical techniques.Also, few literatures exist with regards to the use of physicochemical and geophysical methods in characterizing petroleum contaminated site in Akwa Ibom State. If these were available,effected monitoring and management of these contaminated sites would have been made possible. This lacuna in knowledge further necessitated this study.

1.4       Justification of Study

Increasing industrialization, continued population growth and heavy demand and reliance on petrochemical products have led to unprecedented economic growth and development. However, this dependence on fossil fuels has resulted in serious environmental issues over recent decades. Currently, petroleum production represents a major cause of ecosystem problems. World annual petroleum production is predicted to reach twelve million metric tonnes (Koshlaf and Ball, 2017). British Petroleum (2015) reported that globally, oil production and consumption grew by 2.1 million barrels per day in 2014. However it has been estimated that between 1.7 and 8.8 million metric tonnes of oil from natural and anthropogenic sources are released into the environment annually (Sihag et al., 2014). Due to this, the effect of petroleum hydrocarbons on the ecosystem, including their eco-toxicity and the potential implications they pose for both environmental and human health is a current area of research focus. In particular, soil pollution has been and remains a severe and widespread environmental hazard attracting considerable public and scientific attention.

Much of this pollution has resulted from the increased activities associated with petroleum exploration, transport and processing. In addition, the lack of waste oil recycling and the disposal of hazardous oil wastes into landfills without sufficient management has further increased the number of contaminated sites. For instance, during 2005 almost nine oil pollution incidents were reported around the world every day, in addition to an estimation of a yearly oil spill of one million tonnes into the UK terrestrial environment alone (Stroud et al., 2007). In the USA, around 90% of the contaminated sites were petroleum hydrocarbon contaminated soils (Stroud et al., 2007; Das and Chandran, 2011). Due to the mobility of petrogenic hydrocarbons together with their toxicity, mutagenicity and carcinogenicity, soil contamination is considered as a major challenge for healthy environments (Gong et al., 2003). The carcinogenic effects of petroleum hydrocarbons are well established with an observed increase in cancer incidences in petroleum-associated workers including skin, lung, bladder, liver and stomach cancers in addition to reproductive, neurologic and developmental effects (Latif et al., 2010; Samanta et al., 2002).

Against this backdrop, there is a clear and urgent need to remediate petroleum hydrocarbon-contaminated areas. Hence, this study is motivated by the strong zeal to examine a petroleum-impacted site using physicochemical and geochemical techniques in order to recommend ways of appropriate handling and management of these contaminants in the environment.

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