Main content area

Depletion and biodegradation of hydrocarbons in dispersions and emulsions of the Macondo 252 oil generated in an oil-on-seawater mesocosm flume basin

Brakstad, Odd G., Daling, Per S., Faksness, Liv-G., Almås, Inger K., Vang, Siv-H., Syslak, Line, Leirvik, Frode
Marine pollution bulletin 2014 v.84 no.1-2 pp. 125-134
alkanes, bacteria, basins, biodegradation, boiling, boiling point, dispersions, droplet size, emulsions, evaporation, genes, oils, polycyclic aromatic hydrocarbons, water pollution
Physically and chemically (Corexit 9500) generated Macondo 252 oil dispersions, or emulsions (no Corexit), were prepared in an oil-on-seawater mesocosm flume basin at 30–32°C, and studies of oil compound depletion performed for up to 15days. The use of Corexit 9500 resulted in smaller median droplet size than in a physically generated dispersion. Rapid evaporation of low boiling point oil compounds (C⩽15) appeared in all the experiments. Biodegradation appeared to be an important depletion process for compounds with higher boiling points in the dispersions, but was negligible in the surface emulsions. While n-alkane biodegradation was faster in chemically than in physically dispersed oil no such differences were determined for 3- and 4-ring PAH compounds. In the oil dispersions prepared by Corexit 9500, increased cell concentrations, reduction in bacterial diversity, and a temporary abundance of bacteria containing an alkB gene were associated with oil biodegradation.