hundreds of thousand tons of ordinary waste. Disposal of hospital wastes contaminates underground waters as well
[11].
Effect of Detergents in Soil
Existence of detergents in sewage will increase soil permeability and microorganisms and even molecules, which
cannot pass ordinarily from soil filters, will able to pass from pores of consecutive and different layers of soil in the
presence of detergents and can cause microbial contamination of the waters which are placed in a relatively high
distance to the ground level [5].
Agricultural Pollution
Excessive use of agricultural fertilizers and pesticides, antibiotics and hormones in livestock and irrigating farms
with contaminated wastewaters are agricultural factors affecting soil pollution. Cancer, nervous, respiratory and skin
diseases are of the long-term effects of pesticides on human. Pesticides are entered the soil in different ways which
include: through direct application of them in soil, through spraying and return of pesticides particles suspended in
the air directly to the ground, toxins absorbed on surface of soil particles suspended in air and their sitting on the
ground and plant residues that are added to the soil and the toxins absorbed by the soil organisms (non-lenticular).
Chemical fertilizers change properties of the soil i.e. lessen soil permeability to the air and water. Generally,
chemical fertilizers harden soils. Chemical pesticides create soil pollution as well. A number of pests especially
insects are strengthened against consumable pesticides. Under such circumstances, we have to either increase the
number of spraying or boost concentration of toxins. These toxins are not decomposed easily and will remain in soil
for many years [14].
Oil Pollution
It is for a long time that oil materials and its derivatives cause soil pollution as a result of transportation or storage.
Oil pollution is an inevitable outcome as a result of rapid population growth and industrialization process, based on
which, soil pollution can be observed by oil hydrocarbon materials vastly around exploration and refining
installations typically via transfer of these materials. In addition to the direct emission of these pollutants, dusts of
burning gases along with oil have managed to add toxic and harmful substances to the soils of the region for long
years. If more oil materials are penetrated into the more depth of soil, removing its pollution is a difficult task and
will cost dearly [4].
Environmental Cleanup Costs
Until 2000, the United States of America has spent approx. 2% of its gross national income to the cleaning up
environment and controlling pollution. The said rate accounts for 50% of the amount which we pay for our garment
and is 33% of the amount which is paid to the military forces. After 2000, the said amount has been increased more
than 8.2 percent of its gross national product (GNP).
Except the Netherlands, no any other country can be found to invest the said rate on the environmental problems
[10].
Soil Pollution in Iran
Based on the statistics, a little percentage of industrial and household wastewater in the country is treated and major
part of the industrial and household sewages of the country is entered the environment as raw which will follow soil
pollution and contamination of underground waters as well. Increased rate of nitrate in water of wells is a clear
evidence of the said claim. Acid rain is one of the cases of soil pollution which is observed less in our country.
Severe opposition to set up a coke mfg. factory in Savadkouh is one of the measures taken by the Department of the
Environment (DoE) to prevent acid rain from falling. The pollution atlas of the Iranian soils is at preparation stage.
If the map is prepared, an exact statistics on degree of soil pollution in the country will be obtained. To date, the
following areas have been reported as the most polluted areas in Iran: Isfahan Province, Southern Tehran, Assaluyeh
in Bushehr, land areas around Sarcheshmeh Copper Mine, Sistan-Baluchestan Province, and a major part of
Khuzestan [7].
Soil Pollution in Tehran
Pollutions caused by oil leakage from oil transmission pipelines in southern Tehran have been reported as one of the
soil pollutants in Tehran. Using agricultural pesticides across Tehran Province is regarded as the other soil
pollutants.
Fall of acid rains, due to the existence of high pollution in Tehran, is the other cases of soil contaminant in this city
[12]