Environmental Engineering Reference
In-Depth Information
features of the area which differ from country to country depending upon the cli-
mate and other geographical conditions. Therefore while using plants for bioreme-
diation, we need to apply native plants or microorganisms for each area involved.
Our aim here is to evaluate the ability of A. retroflexus and its root associated fungal
species for remediation of petroleum polluted soils.
1.1
Study Site
Kermanshah oil refinery is located in Kermanshah city (previously named Bakhta-
ran) in the west of Iran, near the border with Iraq (Mohsenzade et al. 2009 ). It is
an old refinery established in 1933, with a production capacity of 25000 barrel a
day. Soils around the refinery are of sandy loam character, containing 85 % sand,
8 % loam, 6 % sludge and 1 % organic matter with 5.9 pH. Chemical composition
of crude oil used in the refinery is as follows; 13.4 % saturated hydrocarbons, 40 %
aromatic hydrocarbons, 46.6 % polar compounds. Regarding the oil refining activi-
ties in this region, a high degree of petroleum pollution was observed in some areas.
The identification of soil contamination was based on a visual examination of the
soil and also experimental assays. A. retroflexuas was collected from the petroleum
polluted area in the refinery. The taxonomical identification was done at Bu-Ali
Sina University.
1.2
Isolation of Fungi Associated with the Roots
Plant root samples with 1 cm length were harvested, washed and dried. The samples
were kept in sodium hypochloride (1 % - 3 min) and then ethanol (70 % - 3 min) for
removing the peripherally attached microorganisms, washed with distilled water,
dried and kept in PDA media containing lactic acid. The petri dishes were incu-
bated in 25 ± 2 °C for 4 days. Different fungal colonies were isolated and cultured
separately in PDA. Fungal specimens were examined under light microscope and
identified using morphological and other taxonomical features (Nelson et al. 1983 ;
Gilman 1998 ; Watanabe 2002 ). The root associated fungi for each plant collected
from the petroleum polluted area were compared with the non-polluted ones in or-
der to find out oil resistant species.
1.3
Determination of the Fungal Growth Ability Under
Petroleum Pollution
Growth assay was used to find out fungal species resistant to soil petroleum con-
tamination. The assays were conducted by comparing the growth rates of fungal
strains, as colony diameter, on the oil contaminated and control petri dishes. Test
dishes were prepared by adding crude oil to warm PDA solution. In order to have a
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