1 Department of Building, Civil, and Environmental Engineering, Concordia University, Montreal H3G 1M8, Canada.
2 Department of Building, Civil, and Environmental Engineering, Concordia University, Montreal H3G 1M8, Canada. Electronic address: zhi.chen@concordia.ca.
3 Natural Resources Canada, CanmetENERGY, Devon T6G 1A8, Canada.
4 Ecosystem Science, Fisheries and Oceans Canada, Ottawa K1C 0E6, Canada.

There is increasing concern over the environmental risks associated with deepwater petroleum exploration activities. The integration of environmental risk assessment and oil spill modeling can help to understand and quantitatively characterize the potential risks from subsea blowouts in specific regions. This study integrates a novel deepwater oil spill model (DWOSM) and an extended stochastic modeling methodology to assess the environmental risk of polycyclic aromatic hydrocarbons (PAHs) during a simulated offshore subsurface blowout off the east coast of Newfoundland, Canada. Additionally, the effectiveness of subsea dispersant injection (SSDI) in spill mitigation was investigated through comparative simulations. Resultant spill hazard and risk maps for current and proposed areas of offshore oil and gas development, in support of contingency plans, revealed that surfaced oil tends to drift toward the southeast and east in the hypothetical blowout case; nearshore areas of east Newfoundland have relatively low risk shortly after a deep-sea blowout; released PAHs may elicit more adverse ecological impacts than volatile organic compounds (VOCs); and SSDI application can reduce contaminant exposure levels but at the expense of enlarging the impacted zone for a short term. This stochastic simulation-based risk assessment provides scientific evidence to support decision-making in strategic oil spill response operations.