Environmental Engineering Reference
In-Depth Information
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a
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b
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Fig. 8.2
Total colony count (CFU/g soil) after 2 months of planting (
a
) Oil-degrading colony
count (CFU/g soil) after 2 months of planting (
b
) (± SD,
n
= 3,
P
< 0.05)
in the soil. The roots and shoots in 7 % sample were very low and there was no root
in 10 % germinated sample. The total dry biomass (roots + shoots) was also high in
0 %, while it was markedly low in 7 and 10 % samples. A sudden decrease in total
dry biomass was observed in 1 % sample in comparison with that in 0 % sample.
Figure
8.2
shows the relationship between the concentration of crude oil in soil
and the number of leaves. The presence of high concentrations of crude oil in soil
reduces the number of leaves; the lower numbers were observed in 10 % sample.
The number of green plants was also shown in Fig.
8.2
. There was no green plant
in 10 % sample at the end of the experiment. The number of green plants decreased
in 7 % sample.
Colony Count
Total colony count and oil-degrading colonies were determined
in vegetated and non-vegetated soils (Fig.
8.2a
). In vegetated samples, the higher
microbial population was observed in 5 and 7 % samples and the lower in control
(0 %). Increasing crude oil concentration increased the total microbial population
in vegetated samples. In non-vegetated samples, the higher microbial population
was also observed in 7 % sample, while the lower at 3 % sample. In all vegetated
samples, the total colonies were higher than their equal concentrations of crude oil
in non-vegetated samples.
Crude Oil Reduction
Fig.
8.3
shows the reduction of crude oil in vegetated and
non-vegetated contaminated soil after 120 days. The higher reduction was observed
in 1 % vegetated sample and the lower in 10 % sample. No significant difference
was observed in vegetated and non-vegetated samples in 10 % sample. Increasing
crude oil concentration decreased the reduction of crude oil in both vegetated and
non-vegetated samples. In all contaminated vegetated soils, the reduction of crude
oil was higher than that in non-vegetated soils, except 10 % sample. A significant
difference in reduction between vegetated and non-vegetated samples was observed
in concentrations up to 5 %.
