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Does the Discharge of Alkylphenols in Produced Water Cause Oestrogenic Endocrine Disruption Among Fish?
Figure 1: Actual and Future Prediction of the Volume of
unrealistically high concentration of PW and would be expected to be
Produced Water Discharged from Oil Installations in the
found only very close to the discharge outlet; a 0.1% PW concentration
Norwegian Sector of the North Sea
represents the estimated PW concentration around oil platforms and
up to 1,000m from the platform; and a 0.01% PW concentration
300
Reinjected
represents the estimated concentration in large areas of the North Sea,
Discharges where many oil platforms contribute to the total output of PW.
250
We did not observe any negative effects on embryo development,
hatching success, sex differentiation, growth or mortality in cod
200
that had been exposed to either 0.1% or 0.01% PW during early
life stages. However, numerous harmful effects were observed
3
in cod exposed to 1% PW. Our studies showed that newly
150
Mill m
hatched yolk sac larvae exposed to 1% PW were unable to start
feeding, resulting in almost 100% mortality (see Figure 2). This
100 shows that newly hatched cod larvae are most vulnerable to the
harmful effects of PW. When cod were exposed to 1% PW at a later
stage (early juvenile), no mortality was observed, demonstrating that
50
these older fish are less susceptible to the effects of PW, probably
due to the fact that their detoxification system is more developed.
However, we did observe significant upregulation of several protein
0
biomarkers, such as VTG (indicating oestrogenic effects) and
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CYP1A (demonstrating PAH exposure). This shows that sublethal
Actual and future prediction of the volumes of PW (mill m
3
) discharged from oil installations in the
effects can also be detected in cod exposed to PW at later
Norwegian sector of the North Sea and Norwegian Sea. The blue segments represent marine discharge
volumes; the red segments represent reinjected volumes (Norwegian Petroleum Directorate, 2007). developmental stages.
Figure 2: Cod Larvae 14 Days Post-hatching from the Unexposed
We also observed long-term effects of exposure to PW. When the early
Group (A) and the Group Exposed to 1% Produced Water (B)
juveniles exposed to 1% PW reached sexual maturity, we found that
they spawned fewer eggs, had a lower rate of fertilisation and a higher
frequency of embryo deformation, resulting in a 74% reduction in the
number of viable offspring. We also observed that cod exposed to
This enormous increase led the
Norwegian government to fund
a research programme to
investigate the potential
biological effects of produced
water in the marine
environment.
The majority of larvae exposed to 1% produced water (PW) did not have food in the intestine (indicated by
arrows). The inability of the larvae exposed to 1% PW to begin feeding resulted in close to 100% mortality
0.1% PW during the juvenile stage had a 32% reduction in the number
due to starvation.
of viable offspring. These results show that PW contains numerous
embryo development and hatching success of the second bioactive compounds that at high doses can have damaging effects on
generation. In addition, we analysed several protein biomarkers, the long-term fitness of cod populations. From these experiments, we
including VTG, cytochrome P450 1A (CYP1A), heat shock protein 70 estimate that, for the early larval stages of cod, the lowest-observed-
(HSP70) and HSP90. There is a need for such long-term studies so effect concentrations (LOECs) for the long-term toxicity of PW are
that valid risk assessment models can be designed to properly between 1 and 0.1% (Meier et al., in preparation).
evaluate the dangers posed by oil production facilities to the
wellbeing of fish populations. Field Studies
IMR has also conducted field studies to determine whether fish
In our experiments we exposed fish to three concentrations of caught close to oil installations (Tampen and Halten Bank) contain
PW: a high dose corresponding to 1% PW; a medium dose elevated levels of APs and other oil hydrocarbons compared with fish
corresponding to 0.1% PW; and a low dose corresponding to from areas with no oil production facilities (Egersund Bank). In
0.01% PW. A 1% PW concentration probably represents an surveys conducted in 2002 and 2005, we did not find any detectable
66
EXPLORATION & PRODUCTION – OIL & GAS REVIEW 2008 – VOLUME 6 ISSUE II
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