Environmental Engineering Reference
In-Depth Information
Fig. 7.2
Culturable het-
erotrophic hydrocarbon
degrading bacteria counts.
Treatment Legend
:
1
Bacteria inoculum only,
2
Bacteria inoculum + worm-
wood,
3
Bacteria inoculum +
wormwood + biosurfactant,
4
Bacteria inoculum + alfalfa,
5
Bacteria inoculum + alfalfa
+ biosurfactant,
6
Bacteria
inoculum + ryegrass,
7
Bac-
teria inoculum + ryegrass +
biosurfactant
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There was no statistically significant difference in dry root or shoot biomass
for treatments with different plants growing in petroleum contaminated soil. Dry
root biomass at 116 days was about 60 ± 26, 54 ± 11 and 14 ± 2 g for wormwood,
alfalfa and ryegrass, respectively. The presence of microbial inoculant did not
affect plant biomass at any time point during this experiment, whereas biosurfac-
tant caused an augmentation of dry plant biomass about 5-7 % more than that by
other treatments.
Despite of the high penetrability of arid soils for hydrocarbons, they are in eco-
logical danger due to poor plant cover, non-diverse microbial pool and low biode-
gradability.
4 Conclusion
Our research indicates the complexity of a phytoremediation system, were pres-
ent even under controlled laboratory conditions. This complexity of interacting
factors which interfere to each other, makes it difficult for researchers to study
the role of the irrespective of factors. Although some research has been done on
interactions occurring in rhyzosphere of contaminated soils, still the mechanism
and effect of biosurfactants facilitated hydrocarbon degradation by complex as-
sociation of plant and bacteria remain exclusive for us. This obvious increase of
phytodegradation can be used to its fullest potential after we completely determine
the interactions that occur in the rhyzosphere along with the factors that influence
these interactions.
