1. Issues and background 1.1 Oil pipe leakage in IraqIn 2006, in Iraq of pollution with crude oil havethe total amount of oil spilled is 565,149 m³ and the quantities of liquid anddry gas leaked were 3560 tons as a result of 113 sabotage accidents of thepipeline in 7 provinces. Most of the incidents were in Baghdad, Kirkuk,Salahuddin, and Basra. On the other hand, fire accidents are continual in anaverage of 20 days during 2006 and mostly in January, August andSeptember. The contaminated soil with crudeoil looks like black film or oil droplets splashing from the pipes that havebeen blown up.
The percentages of hydrocarbon compounds in soil samples inlight polluted soil were 0.02-0.08% and 0.
49-13.2% in highly polluted soils.These percentages decreased with the depth of soil (Ghazi, M.M. and Aqeel, R.L., 2014) 1.2 Impact due to pipe leakageSoil fertility The toxicity of thehydrocarbon components that can affect the soil properties and plant growth canbe identified as follows: i.
Lack of oxygenin soil caused by high concentrations of hydrocarbon gases and carbon dioxidethat will affect biological processes of plant roots and microorganisms. Thiswill result in the infertile soil. ii. The heavyhydrocarbon blocks soil pores and consequently decreasing the permeability orporosity and water movement, and increase the difficulty of plant’s rootspenetration.
The plant can’t grow in this particular polluted soil. iii. Spoilt thesoil structure and decreasing water holding capacity. Thus the soil dry and arenot suitable for living organism. Lack of water will result to die as water arean important component in all living organism.
iv. The nutrientsthat should be used by plants due to element competition and pH variation willbe depleted. In Iraq, an experimental study was conducted on plates of claysoil that contaminated with kerosene and gas oil (5% contamination), referAl-Azaawi (Al-Azaawi, D. F. 2000).
The results showed that these two materialshave adversely affected the production of yellow corn. In the experiment, itwas found that the increase of the production is related to the decompositionrate of the oil products, and the decreasing of the infiltration rate to thedecreasing of the pollution concentration. Meanwhile, there was no variation inthe pH and electrical conductivity of polluted soils. (Al-Khafaji, A.A., Askar,S.
R., and Kasal, S.M.
, 1986; Ellis, R., and Adams, R.S., 1961). Thus provingthat this problem will give some impact in the future by decrease the soilfertility.
1.2.1 Water sourceThe hazardouscharacter of oil mostly due to its toxicity and compounds that do not degradeor chemically breaks up easily. Some of them are circling into the food chainand accumulates in living organisms while others are very complicated and noteasily transmitted and have low toxicity. However, the presence of oil on thesurface affects the seed germination rate and water absorption by theplant. There are a big number ofchemical compounds used in the petroleum industry such as the additives in thedrilling process, oil refining and which is used in the removal of fat anddeadly lichens, fungi and so on. Their movement direction must be tracedbecause most of the compound have harmful effects and negative impact on theenvironment, especially on agricultural production. Crude oil and theassociated materials contain large amounts of salt, such as sodium chloride andcalcium chloride together with the materials that are added during drillingoperations.
These salts can contaminate the soil during leakage orspillage. The clay waste resulting fromdrilling operations can also pollute the environment as it contains heavymetals. These metals are not easily decomposed by nature and can transport tolong distance by water.
Most of these heavy metals are harmful to humansthrough drinking water or food, and their effect can be a cumulative and toxic(Al-Khafaji, A.A, 1994; Al-Omar, M.A., 2001; Kiely, G., 1996).
1.2.2 Future effect on human activities Based on theexperiment on how the oil pollution affected the soil fertility by using theAtterberg limits of clay soil test using hydrocarbons liquid instead of watershow that soil may loss viscosity and behaves as a coarse soil (dry andinfertile soil).
This happens as hydrocarbons liquids are neutralized,non-polarized and cannot contain clay particles (as water) (Fernandez, F., andQualgly, R., 1989; Foreman, D.
E., and Danial, D.E., 1986; Uppot, J.
,and Stephenson, R., 1989). When mixing the hydrocarbons liquid (low isolationrate) with clay soil, it causes shrinkage of the double layer, which containssoil particles and reduces their fluctuation and consequently reduces the speedof settlement. In case of compactionusing organic hydrocarbons liquids, it was found that the permeability isdirectly proportional to the isolation rate, because of the variation of thedouble layer thickness that contains the particles of the soil (Foreman, D.
E., and Danial, D.E.
, 1986 ). In Iraq,Nashat and Dalaly (1998) have conducted an experiment to study the influence ofsome oil products on the engineering properties on clay and silt soil. Theresults show a negative effect on the soil as can be seen in Table 1. Table 1 Effect of the Kerosene and gasoline onsoil properties (Nashat, A.
H., and Dalaly, N.K., 1998). Liq.
Liq. Plas. Plas.
Void Comp. Limit Limit Index Type Ratio (kN/m2) (%) (%) (%) Water 92 41 51 0.78 284 Kerosene 119.5 42.8 76.
7 0.82 33 Gasoline 114.2 40.8 73.4 0.88 450 Note: Liq.
=Liquid, Pls.=Plastic/Plasticity, Comp.=Compressibility. In order to understandthe oil impact on the soil properties, a simple laboratory experiment wasperformed to study the effect of mixing used motor oil (10%) with clay soil.The mixture then burned in a furnace at a temperature of 700-800 degreeCelcius, simulating burning as one of the methods used in the treatment ofoil-contaminated soils.
The results as shown in Table (2) match with theresults of the experiment conducted by Al-Azaawi (2000), and Nashat and Dalaly(1998). It was found that the used oil increase the Atterberg limits for bothmixed soils and burned soils. Thus, oil has a negative impact on the soilproperties which may affect the plant production. This two experiment provide abasic hypothesis that oil spillage impact to the soil fertility will worsen thesoil condition in the future and will also affect the human diets as the toxicchemical might accumulate in the food chain increased. The insoluble chemicalwill be accumulated in the food chain while the soluble chemical might affectthe water quality. Thus both ways, this will give a bad impact in the future. Table 2 The impactof motor used oil on the soil properties before and after burning.