Environmental Engineering Reference
In-Depth Information
Numerous sites are contaminated worldwide with crude or refined oil in differ-
ent countries and also in Iran. Since in different areas, various ecological conditions
with different climates are present, we need to apply native plants or microorgan-
isms for bioremediation of newly subjected areas. The aim of this paper is to evalu-
ate the ability of
Senecioa glaucus
and its root-associated fungal species for the
remediation of crude oil-polluted soils.
2
Materials and Methods
Senecio glaucus
L. was collected from the Abadan oil refinery, located near the
coast of the Persian Gulf. It was completed in 1912 and was one of world's largest
oil refineries before it was largely destroyed in 1980. The refinery had a capacity of
635,000 b day
−1
in 1980 and formed a refinery complex with important petrochemi-
cal plants. Its capacity has increased steadily from 1988 onwards and is now listed
as 429,000 barrels per day (68,200 m
3
day
−1
) crude oil.
Soil characters of the refinery were evaluated as sandy loam containing 85 %
sand, 10 % loam, 4 % sludge and 1 % organic material, with pH 6.1. The crude oil
used in the refinery contains 14.6 % saturated hydrocarbons, 39 % aromatic hydro-
carbons, 44.4 % polar compounds (Refinery office data). The refining activities in
this region lead to a high degree of oil pollution in some areas. Identification of soil
pollution was done visually as well as through experimental assays.
S. glaucus
was
collected from the oil polluted areas in the refinery. The taxonomical identity was
carried out in Bu-Ali Sina University.
Plant root samples with 1 cm length were harvested and dried at room tem-
perature after washing with distilled water. Samples were incubated in 1 % sodium
hypochloride followed by ethanol 70 % (3 s), for removing the peripherally attached
microorganisms. These were washed with distilled water (three times) and dried
using sterile paper (Mohsenzade et al.
2009
). The samples were kept in petri dishes
containing sterile PDA media, incubated in an incubator at 25 ± 2 °C for 3 days. Dif-
ferent fungal colonies were isolated and transferred to PDA media. Fungal colonies
and their mycelia were examined under light microscope after preparations and
were identified using morphological characters and taxonomical keys (Nelson et al.
1983
; Gilman
1998
; Watanabe
2002
). The root-associated fungi for the plants were
collected from the oil-polluted area and compared with the non-polluted ones to
find out oil resistant fungal species.
The growth assay was done to find the fungal species resistant to oil contamina-
tion of the soil by comparing the growth rates of fungal strains, as colony diameter,
on the oil contaminated and control Petri dishes. Test dishes were prepared by add-
ing different concentrations of crude oil (1 %, 4 %, 10 %) to warm sterile PDA and
then left on a shaker. In order to have a uniform concentration of oil in all plates,
the solution was thoroughly mixed with a magnetic stirrer, right before it was added
to the plates. Three concentrations of Oil/PDA mixture (1 %, 4 %, and 10 % w/w)
were prepared. Pure PDA was used in the control plates. All dishes were inoculated
