ABSTRACT
Spilled oil mixed with seawater and entrained water bubbles in an oil slick can potentially form an emulsion. The emulsified oil (i.e., the emulsion) has a significantly increased viscosity, which poses extra challenges to oil spill response. Existing information related to the stability of seawater-in-oil emulsions is based on the behavior of emulsions in small, closed systems (e.g. small flasks), and some studies have shown that some emulsified oils that exhibited stable behavior in the lab readily spread into sheen in an uncontaminated open water system. We have constructed a mesocosm scale flume tank equipped with artificial solar lamps, white-cap mixing water jets, Langmuir cell mixing, and two weirs to remove diffuse sheening components. In this case, the oil spreading is designed to be ‘infinite’ and the oil weathering process is in a mostly ‘natural’ environment in this 8-meter-long, 0.6-meter-wide, and 0.3-meter-deep flume tank, which is filled with 33 g/kg artificial seawater (Instant Ocean). The system can be operated remotely and monitored through the web. Oil samples were collected at 0 h, 1 h, 6 h, 9 h, 24 h, 48 h, and 72 h to monitor changes in physical-chemical properties such as density, viscosity, interfacial tension, water content, water bubble size distribution, and oxygenates with FTIR, etc. The results, we argue, approach reality and could help establish an oil spill prediction model, as many natural processes were considered and simulated.