International Journal of Marine Science 2015, Vol.5, No.27: 1-11
4
correlation in different treatments ranged between
-0.65 – -0.93. After 23-60 days of treatment, the rate
of oil degradation dropped. Then, population growth
became almost stagnant at 60-90 days after treatment
and entered the decline phase.
2.3 Environmental conditions
The experiment was conducted in the dynamic
envir-
onment of an estuary
(Figure
3). Pore water conditions
inside and outside mesocosm were
different. Oxygen
availability, pH and redox potential in the pore water
outside the mesocosm were higher than inside the
mesocosm (Table 2). In situ data during the experiment
was available for surface seawater temperature inside
the mesocosm which was in the range of 25.2 –
29.30
o
C (27.25 + 0.83
o
C).
Table 2 Pore water quality over time experiment inside and outside mesocosm
Parameter
Inside mesocosm (n =72)
Outside mesocosm (n = 6)
Range
Mean + SD
Range
Mean + SD
DO (mg/L)
0.17 – 3.24
0.74 + 0.59
2.24 – 4.95
4.16 + 1.11
Salinity (ppt)
13 – 56
35 + 7.40
27 – 34
30.2 + 2.58
pH
6.25 – 7.3
6.62 + 0.17
6.61 – 7.39
6.93 + 0.32
ORP ( mV)
(-518) –151
(-124.438) + 180.85
22 – 120
65.25 + 40.65
Figure 3 Pore water quality in each treatments over time mesocosm experiment. (n=3 for each sampling time ). Parameters measured
were A (salinity), B (Redox potential, C (pH) and D (Dissolved Oxygen). The treatments included C ( oiled sediment only); F (oiled
sediment + fertilizer 15 g N/kg); FSC (oiled sediment + fertilizer 7. 5 g/kg + single strain 2.5L, 8 x 10
8
cell/mL), and FCC (oiled
sediment + fertilizer 7.5 g/kg + consortium 2.5L, 8 x 10
8
cell/mL)
The availability of oxygen in pore water declined
during the experiment, not only in the bioremediation
treatment mesocosm, but also in the control
mesocosm, although, the depletion rate in the control
was lower than in the treatment (Figure 3 A). The
decrease of DO in the treatments were significant until
8 days after treatment, after which it was stable to the
value < 0.5 mg/L until the end of experiment. The
lowest average DO value was 0.30 mg/L which was
observed in the FSC treatment 90 days after
incubation, whereas the highest average value, which
was 0.90 mg/L, occured in the fertilizer-only
treatment
