Environmental Engineering Reference
In-Depth Information
Ϯ͘Ρ
ΕϬ
Ϭϴ
ZŽŽƚƐН^ŚŽŽƚƐ
ZŽŽƚƐ
'ĞƋŴŜŶĂƟŽŶ
ϴϬ
ϬϹ
>ĞĂǀĞƐ 'ƋĞĞŶƉŮĂŶƚ
Ϯ
ϬΚ
ϳϬ
ϬϮ
ϹϬ
Ϭ͘Ρ
ϬϬ
ΡϬ
ϴ
ΚϬ
Ϭ
Ϲ
ϮϬ
Κ
ϮϬ
Ϭ͘Ρ
Ϯ
ϬϬ
Ϭ
Ϭ
Ϭ
b
Ϭ
Ϭ
Ϯ
Ρ
ϳ
ϬϬ
a
Ϭ
Ϭ
Ϯ
Ρ
ϳ
ϬϬ
ƋƵĚĞŽŜŮ;ЙͿ
ƋƵĚĞŽŜŮ;ЙͿ
Fig. 8.1 a
The number of germinations in different concentrations of crude oil after 30 days of
seeding and total dry biomass (shoots + roots) and dry biomass of roots after 120 days of plant-
ing.
b
The number of leaves in vegetated samples after 30 days of seeding, and number of green
plants after 120 days (end of experiment) of planting. Average values ± standard deviation (± SD),
P
< 0.05
also the number of green plants was counted at the end of the experiment. The plant
biomass was collected at the end (120 days) of the experiment, dried at room tem-
perature and reported as total dry weight for roots and shoots. The colony count was
done for the determination of total colonies and also for oil-degrading colonies of
soil, 60 days after planting. Determination of total colonies in soil was done by the
pure-plate
method with nutrient agar as medium. Determination of oil-degrading
colonies was also done by the same method in agar-agar with 1 % sterilized light
crude oil as sole carbon source. Crude oil extraction was conducted according to the
method used by Minai-Tehrani and Herfatmanesh (
2007
). For 48 h, 1 g of treated
soil was dried in 50 °C then crushed well to make a homogenous soil. An aliquot of
10 ml of CH
2
Cl
2
(Aldrich) was added to the soil and shaken firmly to separate the
oil from the soil. The sample was centrifuged (3,000 ×
g
for 10 min.) to precipitate
the soil, and the solvent phase removed. The solvent extraction was repeated twice.
The solvent vaporized during 24 h and the amount of oil was measured by the gravi-
metric method and its reduction compared with time zero. Two samples from each
replicate were taken for crude oil extraction.
3 Results
Germination, Growth and Biomass
The germination number in the vegetated
samples was high in 0 % sample and it was low in 10 % sample (Fig.
8.1
). There
was a sharp reduction in number of germinations above 5 % concentration of
crude oil. Dry biomass of roots and shoots were measured 120 days after seeding
(Fig.
8.1
). The separation of roots from the soil showed that the distribution of
roots in the soil decreased by increasing the crude oil concentration. The higher
root biomass was observed in 0 % sample, in which the roots were well distributed
