Abstract
The activities of the oil industry are increasing in the polar and the deepwater regions, with the risk for oil discharges in these environments. Following discharges to the marine environment the oil is exposed to a variety of physical, chemical and environmental processes, and in polar regions these include low temperature and ice formation. Even the Deepwater Horizon accident represents an oil discharge to permanently cold environments, since most of the oil plume was trapped in deep water. Determination of biodegradation rates in cold seawater systems depends on a number of factors, including experimental systems, temperatures (including ice formation), and bioavailability of compounds. We have studied hydrocarbon (HC) biodegradation in temperate to cold seawater and in marine ice and shown that that biodegradation of oil hydrocarbons (HCs) like n-alkanes and polycyclic aromatic hydrocarbons (PAHs) may be considerable even at temperatures of 0°C. However, in marine ice n-alkane degradation may become negligible, while biodegradation of soluble aromatic HCs still appears. We have also compared design of experimental systems, as well as the impact of oil film thickness on HC biodegradation. Biodegradation rates have been included as a parameter in numerical fate and exposure models for the predictions of the environmental impacts of marine oil spills. While Alphaproteobacteria and Gammaproteobacteria are associated with HC biodegradation in temperate seawater, genera of Gammaproteobacteria and Bacteroidetes classes are abundant in oil-polluted cold seawater. Also in marine ice oil addition has resulted in the stimulation of a few indigenous genera of Gammaproteobacteria during winter field experiments. Bioremediation may be a cost-effective tool for secondary oil-spill removal in Arctic environments, often in combination with other technologies. Biostimulation experiments conducted on beaches at Svalbard and laboratory studies under simulated conditions have shown
