ORIGINAL ARTICLE Fate of Surface Spills of Cold Lake Blend Diluted Bitumen Treated with Dispersant and Mineral Fines in a Wave Tank Thomas L. King, 1, ** Brian Robinson, 1 Claire McIntyre, 1 Patrick Toole, 1 Scott Ryan, 1 Firas Saleh, 2 Michel C. Boufadel, 2, * and Kenneth Lee 3 1 Department of Fisheries and Ocean Canada, Centre for Offshore Oil, Gas and Energy Research, Bedford Institute of Oceanography, Dartmouth, Canada. 2 Center for Natural Resources Development and Protection, Department of Civil and Environmental Engineering, New Jersey Institute of Technology, Newark, New Jersey. 3 Wealth from Oceans National Research Flagship, CSIRO, Australian Resources Research Centre, Kensington, Australia. Received: October 8, 2014 Accepted in revised form: November 20, 2014 Abstract Cold Lake Blend (CLB) diluted bitumen (dilbit) was used to evaluate the fate and transport of preweathered (6.2% w/w) dilbit under environmental conditions both in spring (seawater temperature 8.5°C – 1.3°C and salinity 27.7 – 1.6 practical salinity units [psu]) and in summer (seawater temperature 17.0°C – 2.6°C and salinity 26.8 – 2.4 psu). The following oil spill treatments were considered: no treatment, dispersant alone, mineral fines (MF) alone, and dispersant + MF. The aim was to determine their influences on the fate of spilled CLB at sea. When dispersant alone was used, the highest dispersion effectiveness (DE) was noted, and DE ranged from 45% to 59% under the selected environmental conditions. With no treatment and treatment of MF alone, CLB DE was insufficient under tested conditions. Total petroleum hydrocarbon (TPH) concentration in the water column was highest for the dispersant alone, followed by that of dispersant + MF. TPH concentration for the dispersant alone increased abruptly with time. Droplet size distribution (DSD) resulting from dispersant alone had a unimodal shape, which was different than previously observed when conventional oils were treated with the dispersant. Cases of dispersant + MF were thus characterized by a broader DSD compared with dispersant only and a gradual increase in TPH concentration. This suggests that MF could be used with dispersant as a means to control the release of toxic compounds into the water column and for better engineering the response. Key words: cold lake blend; diluted bitumen; dispersant; dispersion effectiveness; mineral fines; wave tank Introduction T he Canadian province of Alberta contains rich de- posits of oil sands, and oil production requires direct mining and in place extraction processes (Read and White- oak, 2003). The raw product is semiliquid at room tempera- ture and is too viscous to be transported economically by pipeline. For these reasons, the bitumen is diluted with either condensate or synthetic oil (Government of Canada, 2013). The final product is called diluted bitumen (dilbit), or synbit when diluted with synthetic oil, and its viscosity and density are similar to those of a heavy crude oil, which make it suf- ficiently fluid for pipeline transportation. Many proposals have been announced and/or anticipated to transport diluted bitumen by pipeline to western coastal ports (e.g., Kitimat, British Columbia) in Canada, where it can be transported by marine tankers to international markets (Government of Canada, 2013). Examples include the pro- posed Northern Gateway pipeline and Kinder Morgan Trans Mountain pipeline (Government of Canada, 2013). The re- sulting increased vessel/tanker traffic would increase the risk of accidental oil spills at sea. Therefore, there is a need to advance the research to broaden the understanding of the fate of dilbit products in marine conditions. In an effort to address these concerns, the Canadian federal government has an- nounced in March 2013 the development of a World Class Tanker Safety System; in addition to tanker safety measures, the program includes research to improve understanding of the fate and behavior of dilbit spilled at sea. A review of the literature (Government of Canada, 2013) identified many knowledge gaps on the fate and behavior of these products, which limit the application of appropriate countermeasures in the event of a spill. *Member of AEESP. **Corresponding author: Department of Fisheries and Ocean Canada, Centre for Offshore Oil, Gas and Energy Research, Bed- ford Institute of Oceanography, 1 Challenger Drive, Dartmouth, NS B2Y 4A2, Canada. Phone: 902-426-4172; Fax: 902-426-1440; E-mail: thomas.king@dfo-mpo.gc.ca ENVIRONMENTAL ENGINEERING SCIENCE Volume 32, Number 3, 2015 ª Mary Ann Liebert, Inc. DOI: 10.1089/ees.2014.0459 1