Report

Tracking Hydrocarbon Plume Transport and Biodegradation at Deepwater Horizon

Science  19 Aug 2010:

DOI: 10.1126/science.1195223

Abstract

The Deepwater Horizon blowout is the largest offshore oil spill in history. We present results from a subsurface hydrocarbon survey using an autonomous underwater vehicle and a ship-cabled sampler. Our findings indicate the presence of a continuous plume over 35 km in length, at approximately 1100 m depth that persisted for months without substantial biodegradation. Samples collected from within the plume reveal monoaromatic petroleum hydrocarbon concentrations in excess of 50 µg L–1. These data indicate that monoaromatic input to this plume was at least 5500 kg day–1, which is more than double the total source rate of all natural seeps of the monoaromatic petroleum hydrocarbons in the northern Gulf of Mexico. Dissolved oxygen concentrations suggest that microbial respiration rates within the plume were not appreciably more than 1 µM O2 day–1.

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