The biodegradation of crude oil in the deep ocean

Oil biodegradation at a simulated depth of 1500 m was studied in a high-pressure apparatus at 5 degrees C, using natural seawater with its indigenous microbes, and 3 ppm of an oil with dispersant added at a dispersant:oil ratio of 1:15. Biodegradation of the detectable hydrocarbons was prompt and extensive (>70% in 35 days), although slower by about a third than under otherwise identical conditions equivalent to the surface. The apparent half-life of biodegradation of the total detectable hydrocarbons at 15 MPa was 16 days (compared to 13 days at atmospheric pressure), although some compounds, such as the four-ring aromatic chrysene, were degraded rather more slowly. (C) 2016 Elsevier Ltd. All rights reserved.