Distribution of water soluble components from Arctic marine oil spills — A combined laboratory and field study

Field experiments dealing with oil encapsulated in ice were performed to study the dissolution of water soluble components (WSC) through first-year sea ice. Six oils (five crude oils and a heavy fuel oil) were frozen into sea ice in February. Oil/ice samples were analyzed and migration of WSC from the oil into the ice was quantified during the 112 day (16 week) experiment. The WSC content in the ice decreased with ice depth, from the upper ice surface to the ice-seawater interface, and a concentration gradient as a function of time was observed. Although the concentrations were low in the bottom ice core (2 to 16 ppb), the exposure time was long. These results indicate that the ice biota could be exposed to toxic WSC in the bottommost centimeters of the ice and in the brine channels, and this could cause potentially toxic oil components to enter the Arctic marine food web. In addition, water accommodated fractions in seawater were generated in the laboratory according to the CROSERF procedure. The distribution of WSC in the field samples was similar to what was observed in the laboratory experiments, confirming that there is a transport of WSC from the oil through the brine channels in the ice to the underlying water.