EFFECT OF SPENT OIL ( ENGINE OIL) ON THE PHYSIOCHEMICAL PROPERTIES OF SOIL
1.1 Background of the study
The disposal of spent engine oil (SEO) into gutters, water drains, open vacant plots and farms is a common practice in Nigeria especially by motor mechanics. This oil, also called spent lubricant or waste engine oil, is usually obtained after servicing and subsequently draining from automobile and generator engines (Anoliefo and Vwioko, 2001) and much of this oil is poured into the soil. There are relatively large amounts of hydrocarbons in the used oil, including the highly toxic polycyclic aromatic hydrocarbons (Wang et al., 2000). Also, most heavy metals such as V, Pb, Al, Ni and Fe, which were below detection in unused lubricating oil, have been reported by Whisman et al. (1974) to give high values (ppm) in used oil. These heavy metals may be retained in soils in the form of oxides, hydroxides, carbonates, exchangeable cations, and/or bound to organic matter in the soil (Yong, et al., 1992). Nevertheless, this is dependent on the local environmental conditions and on the kind of soil constituents present in the soil-water system. Ekundayo et al. (1989) have shown that a marked change in properties occurs in soils polluted with petroleum hydrocarbons, affecting the physical, chemical and microbiological properties of the soil. Oil pollution of soil leads to build up of essential (organic C, P, Ca, Mg) and non-essential (Mg, Pb, Zn, Fe, Co, Cu) elements in soil and the eventual translocation in plant tissues (Vwioko et al., 2006). Although some heavy metals at low concentrations are essential micronutrients for plants, but at high concentrations they may cause metabolic disorders and growth inhibition for most of the plant species (Fernandes and Henriques, 1991). However, plants respond differently to pollutants. Anoliefo and Vwioko (1995) reported that the contamination of soil with spent engine oil caused growth retardation in plants, with the effect more adverse for tomato (Lycopersicom esculentum) than pepper (Capsicum annum L.). Maize (Zea mays L.), a major cereal in Nigeria and many African countries, was chosen for this study because it has become increasingly popular and most farmers have adopted its cultivation. This study aims to evaluate the effects of spent engine oil on soil properties. In urban areas, various types of activities like agriculture, industry and transportation produce large amount of wastes which are classified as either agricultural, industrial, municipal or nuclear wastes (Onwuka et al., 2012). These wastes from various sources are deposited on the soil surfaces either deliberately applied as fertilizer, sprays or pesticides (Lauhanen et al., 2004) or inadvertently through small or large leaks (Adesodun, 2014) as solids, plastics, crude oil or spent engine oil. Some of these wastes can be recycled into some important products that can be used to meet with the challenges arising from increasing population of Nigeria. They can be recycled into manures and fertilizers for production of crops and animals among others (Onwuka et al., 2012). There are others that cannot be converted into any beneficial secondary use and therefore pose a serious threat to the environment and one of such is spent engine oil (Onwuka et al., 2012). Spent oil sometimes referred to as waste engine oil is produced from automobile mechanic shops and mechanical or electrical engine repairers’ shops (Anoliefo and Vwioko, 2001) after servicing the vehicles engines, generating set and other types of engines. It has dark brown to black colour and it is harmful to the soil environment (Adedokun and Ataga, 2007). This is because it contains a mixture of different chemicals including low to high molecular weight (C15-C21) compounds, lubricants, additives and decomposition products and heavy metals which have been found to be harmful to the soil and human health (Duffus, 2002). According to Ekundayo et al. (1989), marked change in properties occurs in the physical, chemical and microbiological properties of soils contaminated with lubricant oil. Oil displaces air and water leading to anaerobic condition (Atlas, 1977). The presence of spent lubricant oil in soil increases bulk density, decreases water holding capacity and aeration propensity (Kayode et al., 2009). The authors also noted reduced nitrogen, phosphorus, potassium, magnesium, calcium, sodium and increased levels of heavy metals in soils contaminated with spent oil. In contrast, Vwioko et al. (2006) noted build up of essential elements such as organic carbon and organic matter and their eventual translocation to plant tissues. These conditions generally cause unsatisfactory seed germination, growth and yield in soil contaminated with spent engine oil. For instance, Odjegba and Sadiq (2002) reported low yield and decreased growth of plant grown in spent lubricant oil contaminated soil. In most cities and towns in Nigeria, some farmers or residents grow vegetables, maize and other crops around the mechanic villages or sink borehole without considering the health risks involved. Researchers such as Wang et al. (2000), Odjegba and Sadiq (2002), Agbogidi and Nweke (2006) and Okonokhua et al. (2007) had worked on effect of spent lubricant oil contamination on soil properties and crop yield but not much work has been carried out on heavy metals uptake by crops in Abakaliki areas. Therefore, the objectives of this study were to study effect of different levels of spent engine oil on soil properties, grain yield of maize and its heavy metals uptake.
1.2 STATEMENT OF THE PROBLEM
Spent oil sometimes referred to as waste engine oil is produced from automobile mechanic shops and mechanical or electrical engine repairers’ shops (Anoliefo and Vwioko, 2001) after servicing the vehicles engines, generating set and other types of engines. It has dark brown to black colour and it is harmful to the soil environment (Adedokun and Ataga, 2007). This is because it contains a mixture of different chemicals including low to high molecular weight (C15-C21) compounds, lubricants, additives and decomposition products and heavy metals which have been found to be harmful to the soil and human health (Duffus, 2002). According to Ekundayo et al. (1989), marked change in properties occurs in the physical, chemical and microbiological properties of soils contaminated with lubricant oil. Oil displaces air and water leading to anaerobic condition (Atlas, 1977). The presence of spent lubricant oil in soil increases bulk density, decreases water holding capacity and aeration propensity (Kayode et al., 2009). It is in view of this that the researcher intend to investigate the effect of spent oil on the physiochemical properties of soil.
1.3 OBJECTIVE OF THE STUDY
The main objective of this study is to ascertain the effect of spent oil on the physiochemical properties of soil. But for successful completion of the study; the researcher intend to achieve the following objectives;
i) To ascertain the effect of spent oil on the physiochemical properties of soil
ii) To investigate the impact of spent oil on soil fertility
iii) To ascertain the relationship between spent oil and the chemical properties of the soil
iv) To ascertain the impact of spent oil on soil degradation
1.4 RESEARCH HYPOTHESES
For the successful completion of the study, the following research hypotheses were formulated by the researcher;
H0: spent oil does not have any significant effect on the physiochemical properties of soil.
H1: spent oil does have a significant effect on the physiochemical properties of soil
H0: spent oil does not have any significant impact on soil fertility
H2: spent oil does have a significant impact on soil fertility
1.5 SIGNIFICANCE OF THE STUDY
It is believed that at the completion of the study, the findings will be of great importance to the department of environmental science, as the study seeks to investigate the effect of spent oil on the physiochemical properties of soil. The study will also be of benefit to agriculturist as the study intends to highlight the dangers of indiscriminate disposal of spent oil on the soil. The study will also be useful to researchers who intend to embark on research in similar topic, Finally the findings of this study will also be immense benefit to government, academia, scholars, researchers and the general public.
1.5 SCOPE AND LIMITATION OF THE STUDY
The scope of the study covers the effect of spent oil on the physiochemical properties of soil; in the cause of the study the researcher encounters some constraint w
Some constraint which limited the scope of the study;
a) AVAILABILITY OF RESEARCH MATERIAL: The research material available to the researcher is insufficient, thereby limiting the study.
b) TIME: The time frame allocated to the study does not enhance wider coverage as the researcher has to combine other academic activities and examinations with the study.
c) FINANCE: The finance available for the research work does not allow for wider coverage as resources are very limited as the researcher has other academic bills to cover
1.7 DEFINITION OF TERMS
Waste oil is defined as any petroleum-based or synthetic oil that, through contamination, has become unsuitable for its original purpose due to the presence of impurities or loss of original properties.
Soil is a mixture of minerals, organic matter, gases, liquids, and countless organisms that together support life on Earth. Soil is a natural body called the pedosphere which has four important functions: it is a medium for plant growth; it is a means of water storage, supply and purification; it is a modifier of Earth's atmosphere; it is a habitat for organisms; all of which, in turn, modify the soil.
Soil porosity refers to the pores within the soil. Porosity influences the movement of air and water. Healthy soils have many pores between and within the aggregates. Poor quality soils have few visible pores, cracks or holes. The way in which a soil is managed can affect its porosity. For example, look at areas around your school where students regularly walk. If the grass is worn away and the soil is exposed, it often looks different because it has been compacted and has had its structure and porosity altered. These are also areas where puddles form because the water is not able to drain away
1.8ORGANIZATION OF THE STUDY
This research work is organized in five chapters, for easy understanding, as follows. Chapter one is concern with the introduction, which consist of the (background of the study), statement of the problem, objectives of the study, research questions, research hypotheses, significance of the study, scope of the study etc. Chapter two being the review of the related literature presents the theoretical framework, conceptual framework and other areas concerning the subject matter. Chapter three is a research methodology covers deals on the research design and methods adopted in the study. Chapter four concentrate on the data collection and analysis and presentation of finding. Chapter five gives summary, conclusion, and recommendations made of the study.
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