Environmental Engineering Reference
In-Depth Information
4 Discussion
The soil pollution with crude oil and its derivers is a major environmental problem
in many countries (Klokk
1984
). Serious risks can occur to the public health and
environment when soil is polluted by crude oil (Nicolotti and Egli
1998
). Results
of this investigation showed that crude oil, in the concentrations up to 10 % cannot
kill this plant species. These results are in accordance with those of an earlier study.
Merkel et al. (
2005
) showed that several legumes and graminoids were found on
the oil-polluted soils with about 5 % pollution. He reported that an indirect effect of
crude oil in the soil is confined to a more or less marked reduction in plant growth
and biomass Merkel et al. (
2004a
,
b
). Some other reports too showed the same
results about other plant species like
Festuca rubra,
Puccinellia maritime
(Baker
1999
),
Trifolium rubra
(Klokk
1984
), and different legumes and grasses (Nicolotti
and Egli
1998
).
Study on fungal species has revealed that
Alternaria, Penicillium
and
Rhizoc-
tonia
were the common fungi that have been observed in the roots of
S. glaucus
plants, both in the polluted and non-polluted soils; but in the oil-polluted soils three
additional fungal strains (
Fusarium acuminatum, F. equisetti, F. reticulatum
) were
observed. Our investigations enlightened the fact that fungal variation in petroleum-
polluted area was more than the non-polluted (Table
12.1
). This means that roots
of the plant species had more fungi yielded in the polluted areas than non-polluted
ones. This goes in line with the finding of some prior researches (Anderson et al.
1993
; Hashem
2007
). It seems that the fungal species use oil compounds as nutri-
ents and crude oil pollution causes an increase in the fungal variation in the oil-
polluted soils. Similar findings have been reported by other researchers (Yateem
et al.
1997
; Eggen and Majcherczykb
1998
; Nicolotti and Egli
1998
; Obuekwe et al
.
2005
; Dritsa et al.
2007
).
In vitro
growth test of the fungi in the PDA media containing different concen-
trations of crude oil showed a species-specific response. Most of the studied fungal
strains were able to grow in 1 % w/v oil pollution and therefore should be consid-
ered for a possible use for the remediation of light soil pollution. Some fungal spe-
cies were inhibited by high oil concentrations (10 % w/w). These species included:
Alternaria
,
Penicillinium
and
Rhizoctonia
while others actually grew very well in
oil-contaminated media, even at very high concentrations. These fungal species are;
Fusarium acuminatum, F. equiseti,
and
F. reticulatum
. It seems that crude oil could
supply essential nutrients for these fungi and they are more effective in oil degra-
dation. Our results are in accordance with the finding of other researchers about
other different fungal species (Yateem et al.
1997
; Eggen and Majcherczykb
1998
;
Nicolotti and Egli
1998
; Obuekwe et al.
2005
; Dritsa et al.
2007
).
Bioremediation of oil-contaminated soil is mainly based on biodegradation in
the rhizosphere and the root-associated fungi are one of the most important factors
in this process (Frick et al.
1999
). The results of our study propose the above-men-
tioned fungi for the future remediation tests and this is the first report about their re-
mediation capacity. It means that the data of this study indicated that isolated strains
of
Fusarium acuminatum, F. equseti
and
F. reticulatum
may have the potential for
bioremediation of crude oil in highly polluted conditions (up to 10 % pollution).
