Simulations of underwater plumes of dissolved oil in the Gulf of Mexico

A simple model of the temperature‐dependent biological decay of dissolved oil is embedded in an ocean‐climate model and used to simulate underwater plumes of dissolved and suspended oil originating from a point source in the northern Gulf of Mexico, with an upper‐bound supply rate estimated from the contemporary analysis of the Deepwater Horizon blowout. The behavior of plumes at different depths is found to be determined by the combination of sheared current strength and the vertical profile of decay rate. For all plume scenarios, toxic levels of dissolved oil remain confined to the northern Gulf of Mexico, and abate within weeks after the spill stops. An estimate of oxygen consumption due to microbial oxidation of hydrocarbons suggests that a deep plume of hydrocarbons could lead to localized regions of prolonged hypoxia near the source, but only when oxidation of methane is included.