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Hibernia is Canada's largest offshore oil platform. Produced water is the major waste byproduct discharged into the ocean. In order to evaluate different potential disposal methods, a comprehensive study was performed to determine the impact from the discharge. Microorganisms are typically the first organisms to respond to changes in their environment. The objectives were to characterize the microbial communities and the chemical composition in the produced water and to characterize changes in the seawater bacterial community around the platform. The results from chemical, physicochemical, and microbial analyses revealed that the discharge did not have a detectable effect on the surrounding seawater. The seawater bacterial community was relatively stable, spatially. Unique microorganisms like Thermoanaerobacter were found in the produced water. Thermoanaerobacter-specific q-PCR and nested-PCR primers were designed, and both methods demonstrated that Thermoanaerobacter was present in seawater up to 1000 m from the platform. These methods could be used to track the dispersion of produced water into the surrounding ocean.

Crude oils dispersed in seawater produce distinct emission spectra when exposed to ultraviolet (UV) light. The spectra can be used to estimate how effectively oil is dispersed by chemical methods. Oil dispersants (such as Corexit 9500) have a pronounced effect on water-based UV spectra, strongly enhancing emission at 445 nm. This enhancement of fluorescence over the 455 nm bandwidth is the result of dispersant breaking up higher molecular weight (> 3 ring) polycyclic aromatic hydrocarbons (PAHs) into stable suspensions of small droplets. Ultraviolet fluorescence spectroscopy (UVFS) has been tested as a rapid analytical tool in the laboratory and in a wave tank designed to investigate the response of crude oils to dispersants and a range of energy dissipation rates. The results obtained with UVFS are consistent with standard chemical analyses, confirming that the method can be employed as a rapid, quantitative measure of dispersed oil concentration. Given that higher molecular weight PAHs are associated with many of the persistent toxic effects of crude oils on marine organisms, UVFS may also prove to be a useful tool for tracking these fractions during dispersed oil toxicity assays.

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