The rise in global energy demand has motivated the exploration and production of oil and gas in increasingly challenging marine environments and there is a continuous risk of accidental oil spills. One of the many fates of spilled oil is deposition on the seabed, which has been extensively studied following the Deepwater Horizon oil spill. However, post-depositional fates of oil in sediments are not well understood. Similarly, the effects of chemical dispersant on oil fate are currently under investigation as their overall contribution to mitigating oil spills environmental impacts remains debated. This project aimed to evaluate the potential for spilled oil to entrain marine sediments and the effects dispersant application had on the process under three transport regimes; (1) post-depositional transport via oil-sediment aggregate deposition in deep-sea sediments, (2) percolative transport in intertidal sands and (3) advective pore-water transport in intertidal and subtidal sands. Investigations into the sorption dynamics of two polyaromatic hydrocarbons in sediment-dispersantseawater systems were also undertaken to evaluate the influence of dispersant application on sorption of hydrocarbons to sediments. Finally, the effects of oil exposure at in situ conditions of pressure and temperature on sediment bacterial community composition were investigated. Oil transport experiments revealed that the tested regimes resulted in significant entrainment of hydrocarbons in marine sediments. Dispersant application resulted in enhanced oil entrainment into sands but not in silts and this effect depended on the water-solubility of hydrocarbons. Watersoluble components were less affected by dispersant than less water-soluble ones. Investigations into sediment bacterial responses to oil exposure at in situ conditions of pressure and temperature revealed a significant effect of both variables on diversity and community composition, highlighting the importance of conducting deep-sea microbial studies at conditions as close to in situ as possible.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:759972 |
| Date | January 2018 |
| Creators | Pérez Calderón, Luis José |
| Contributors | Witte, Ursula ; Anderson, James Arthur ; Gallego, Alejandro |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=238377 |
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