Environmental Engineering Reference
In-Depth Information
be due to presence of high concentration of crude oil in the soil that prevented the
fast evaporation of water from the soil. Thus, the contaminated soils were always
wet in the microenvironment area of the soil. Consequently, in the soil with higher
concentrations of crude oil, the presence of water in microenvironment could also
prevent the diffusion of non-polar toxic materials of crude oil into the microenvi-
ronment which could help the bacteria to be vigorous, but the absence of sufficient
oxygen reduces the crude oil degradation by the bacteria in the samples with high
crude oil concentration. The oily shield may prevent free diffusion of oxygen to
microenvironment area in the soil. Oxygen plays an important role in the biodegra-
dation of crude oil and its components (Von Wedel et al.
1998
; Ahamed et al.
2010
).
Our results also showed that in all the vegetated samples the microbial popula-
tions were higher than the non-vegetated samples, suggesting that the presence of
roots in the soil could increase the microbial population in comparison with that
in non-vegetated samples. The comparison of crude oil reduction in the vegetated
and non-vegetated soils showed that in all the vegetated samples the crude oil re-
duction was higher than that in the non-vegetated samples. It has been shown that
the planted contaminated soil had higher efficiency of reducing oil than did the
unplanted soil (Pradhan et al.
1998
; Minai-Tehrani
2008
). The high reduction of
crude oil in the 1 and 3 % vegetated samples suggests that the oil reduction has been
enhanced in the presence of well distributed plant roots, and the plant roots play an
important role in removal of crude oil and its components. Almost equal reduction
of crude oil in the vegetated and the non-vegetated of 7 and 10 % samples suggests
the importance of the presence of plant roots and their role in reduction of crude oil.
5 Conclusion
In conclusion,
Festuca arundinacea
is a tolerant plant for growing in the oil-pollut-
ed soil. This plant might be a good choice for phytoremediation with low concentra-
tion of crude oil contaminated—soil, while the high concentration of crude oil could
be harmful for this plant. A well distributed of root in the soil and microenvironment
around the roots is two important factors for better degradation of contamination
and increasing bacterial population in the soil.
References
Ahamed F, Hasibullah M, Ferdouse J, Anwar MN (2010) Microbial degradation of petroleum
hydrocarbon. Bangladesh J Microbiol 27(1):10-13
Al-Mailem DM, Sorkhoh NA, Al-Awadhi H, Eliyas M, Radwan SS (2010) Biodegradation of
crude oil and pure hydrocarbons by extreme halophilic archaea from hypersaline coasts of the
Arabian Gulf. Extremophiles 14(3):321-328
Aprill W, Sims RC (1990) Evaluation of the use of prairie grasses for stimulating polycyclic aro-
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