Solar induced emulsification in neat films and petroleum on water

The emulsion capabilities of Deepwater Horizon oil (Macondo well), surrogate oil from a nearby well, and heavy fuel oils [National Institute for Standards and Technology (NIST) standard 2717a and 1619b] were evaluated following exposure to simulated sunlight for up to 48 hours. The selected oil types ranged from light-sweet to heavy-sour crude oil. Emulsification capabilities of the neat oil exposed to sunlight and oil over pure water or seawater exposed to sunlight were assessed via a bottle test for emulsification. Dark controls and a heated (50°C) dark control were included. Qualitative measures revealed a positive correlation between emulsion stability and irradiation time. As little as one hour of simulated sunlight exposure was enough to cause observable emulsification, although the stability of the emulsions at short irradiation times was less than that for longer irradiation times. Studies with varying oil volumes demonstrated a concentration dependence of emulsification ability. Although all oils showed increased emulsification capacity with solar exposure, the behavior of each oil was different. These results confirm that sunlight is an important factor in the emulsification of oil spilled in aquatic systems and demonstrates the impact of irradiation time and other parameters on the likelihood of emulsification. Such emulsification has dramatic effects on the fate, transport, bioavailability, and toxicity of spilled oil, and is one pathway through which sunlight has a major impact on oil spills. This dataset includes qualitative ratings of the degree of emulsification for controls, neat heated oil, neat irradiated oil, irradiated oil on petroleum film, and irradiated oil on seawater for a range of irradiation times and oil types. The dataset also includes photos of the results as well as a descriptive legend and explanation of the result rating system.