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Hydrodynamics play a critical role in determining the trajectory of an oil spill. Currents, stratification and mesoscale processes all contribute to how a spill behaves. Using an industry‑leading oil spill model, we compare forecasts of oil dispersion when forced with two different hydrodynamic models of the North-West European Shelf (7 km and 1.5 km horizontal resolution). This demonstrates how the trajectory of a deep water (>1000 m) release in the central Faroe-Shetland Channel is influenced by explicitly resolving mesoscale processes. The finer resolution hydrodynamic model dramatically enhances the horizontal dispersion of oil and transports pollutant further afield. This is a consequence of higher mesoscale variability. Stratification influences the depth of subsurface plume trapping and subsequently the far-field transport of oil. These results demonstrate that the choice of hydrodynamic model resolution is crucial when designing particle tracking or tracer release experiments., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Crown Copyright © 2020. Published by Elsevier Ltd. All rights reserved.)

During accidental crude oil spills and permitted discharges of produced water into the marine environment, a large fraction of naturally occurring oil components will be contained in micron-sized oil droplets. Toxicity is assumed to be associated with the dissolved fraction of oil components, however the potential contribution of oil droplets to toxicity is currently not well known. In the present work we wanted to evaluate the contribution of oil droplets to effects on normal development of Atlantic cod (Gadus morhua) through exposing embryos for 96 h to un-filtered (dispersions containing droplets) and filtered (water soluble fractions) dispersions in a flow-through system at dispersion concentrations ranging from 0.14 to 4.34 mg oil/L. After exposure, the embryos were kept in clean seawater until hatch when survival, development and morphology were assessed. The experiment was performed at two different stages of embryonic development to cover two potentially sensitive stages (gastrulation and organogenesis). Exposure of cod embryos to crude oil dispersions caused acute and delayed toxicity, including manifestation of morphological deformations in hatched larvae. Oil droplets appear to contribute to some of the observed effects including mortality, larvae condition (standard length, body surface, and yolk sac size), spinal deformations as well as alterations in craniofacial and jaw development. The timing of exposure may be essential for the development of effects as higher acute mortality was observed when embryos were exposed from the start of gastrulation (Experiment 1) than when exposed during organogenesis (Experiment 2). Even though low mortality was observed when exposed during organogenesis, concentration-dependent mortality was observed during recovery., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Crude oil that is inadvertently spilled in the marine environment can interact with suspended sediment to form oil-mineral aggregates (OMA). Researchers have identified OMA formation as a natural method of oil dispersion, and have sought ways to enhance this process for oil spill remediation. Currently there is a lack of understanding of how the weathering of oil will affect the formation of OMA due to a lack of published data on this relationship. Based on literature, we identified two conflicting hypotheses: OMA formation 1) increases with weathering as a result of increased asphaltene and polar compound content; or 2) decreases with weathering as a result of increased viscosity. While it is indeed true that the viscosity and the relative amount of polar compounds will increase with weathering, their net effects on OMA formation is unclear. Controlled laboratory experiments were carried out to systematically test these two conflicting hypotheses. Experimental results using light, intermediate, and heavy crude oils, each at five weathering stages, show a decrease in OMA formation as oil weathers., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Adsorption of suspended particles to the interface of surfactant-dispersed oil droplets can alter emulsion phase and sedimentation behavior. This work examines the effects of model mineral aggregates (silica nanoparticle aggregates or SNAs) on the behavior of oil (octane)-water emulsions prepared using sodium bis(2-ethylhexyl) sulfosuccinate (DOSS). Experiments were conducted at different SNA hydrophobicities in deionized and synthetic seawater (SSW), and at 0.5mM and 2.5mM DOSS. SNAs were characterized by thermogravimetric analysis (TGA) and dynamic light scattering (DLS), and the emulsions were examined by optical and cryogenic scanning electron microscopy. In deionized water, oil-in-water emulsions were formed with DOSS and the SNAs did not adhere to the droplets or alter emulsion behavior. In SSW, water-in-oil emulsions were formed with DOSS and SNA-DOSS binding through cation bridging led to phase inversion to oil-in-water emulsions. Droplet oil-mineral aggregates (OMAs) were observed for hydrophilic SNAs, while hydrophobic SNAs yielded quickly sedimenting agglomerated OMAs., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Oil-suspended particulate matter aggregation (OSA) has been recognized by the oil spill remediation community to effectively enhance the cleansing of spilled oil in the marine environment. While studies have investigated the application of mineral fines as an effective method to facilitate oil dispersion, decision-makers still lack information on the role of mixing energy in OSA formation and its significance to oil dispersion in real spills. This work studied the effect of level and duration of mixing energy on OSA formation using the standard reference material 1,941 b and Arabian light crude oil. The results showed that dispersed small oil droplets increased with an increase of both the level and duration of mixing energy to form multi-droplet OSAs. The sizes of the dispersed droplets varied between 5 and 10 μm under different conditions studied. The maximum oil trapping efficiency increased from 23% to 33%, the oil to sediment ratio increased from 0.30 to 0.43 g oil/g sediment, and the required shaking time decreased from 2.3 to 1.1h as the shaking rate increased from 2.0 to 2.3 Hz. Based on the size measurement results, a breakage effect on the formed OSAs and sediment flocs was confirmed under high mixing energy level., (Copyright © 2013 Elsevier B.V. All rights reserved.)

The process of oil-suspended particulate matter aggregation (OSA) has been recognized by the oil spill remediation community to enhance the natural cleansing of oiled shorelines. A laboratory study was conducted to investigate the kinetics of OSA formation under various mixing intensities using the standard reference material 1941b and Arabian heavy crude oil. The results showed that formation of OSAs increased exponentially with mixing time and reached a maximum within 5h. The maximum oil trapping efficiency increased from 24% to 47%, and the required shaking time decreased from 4.5 to 1.2h as the sediment concentration and mixing energy increased. The maximum oil-to-sediment ratio reached 0.24-0.68 g oil/g sediment within 5h. Most of the formed OSAs were solid OSAs and single droplet OSAs with low mixing energies, and multi-droplet OSAs with high mixing energies. The sizes of the dispersed oil droplets and OSAs were also investigated., (Copyright © 2013 Elsevier Ltd. All rights reserved.)