Based a furnace at a temperature of 700-800

Based on the
experiment on how the oil pollution affected the soil fertility by using the
Atterberg limits of clay soil test using hydrocarbons liquid instead of water
show that soil may loss viscosity and behaves as a coarse soil (dry and
infertile soil). This happens as hydrocarbons liquids are neutralized,
non-polarized and cannot contain clay particles (as water) (Fernandez, F., and
Qualgly, R., 1989; Foreman, D.E., and 
Danial,  D.E., 1986; Uppot, J.,
and Stephenson, R., 1989). When mixing the hydrocarbons liquid (low isolation
rate) with clay soil, it causes shrinkage of the double layer, which contains
soil particles and reduces their fluctuation and consequently reduces the speed
of settlement.  In case of compaction
using organic hydrocarbons liquids, it was found that the permeability is
directly proportional to the isolation rate, because of the variation of the
double 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 of
some oil products on the engineering properties on clay and silt soil. The
results show a negative effect on the soil as can be seen in Table 1.

In order to understand the oil impact on the soil
properties, a simple laboratory experiment was performed 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 degree Celcius, simulating burning as one
of the methods used in the treatment of oil-contaminated soils. The results as
shown in Table (2) match with the results 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 both mixed soils and burned soils. Thus, oil
has a negative impact on the soil properties which may affect the plant
production. This two experiment provide a basic hypothesis that oil spillage
impact to the soil fertility will worsen the soil condition in the future and
will also affect the human diets as the toxic chemical might accumulate in the
food chain increased. The insoluble chemical will be accumulated in the food
chain while the soluble chemical might affect the water quality. Thus both
ways, this will give a bad impact in the future.