Poac ’ 11

A BST R A C T With increased interest in economic development of Arctic resources and waterways, understanding the fate of oil spills in the presence of sea ice becomes crucial for successful spill response and remediation efforts. We performed a series of laboratory experiments to analyze the entrainment and upward migration of oil (Alaska North Slope Crude and synthetic oil) through sea ice as a critical process constraining the timing and strategy of response to oil spills in ice. It was found that oil is entrained into the pore network of growing sea ice and confined to the region near the growing interface where the porosity is above 8 to 15%. This assessment of a minimum entrainment and migration porosity provides a bound on the movement of oil through the microscopic pore network of sea ice. The volume of ice that oil can permeate this way depends on the porosity profile of the ice, which is a function of the temperature profile and bulk salinity profile. Based on these laboratory measurements and consistent observations from past experiments, we hypothesize that stratified oil entrainment takes place if the porosity exceeds a threshold. In addition, oil is able to entrain narrow channels (<2 mm diameter) near the ice–water interface. While the contribution of channel entrainment to the total oil content of the ice is very small, oil in channels appears to be important during the melt season.