Polycyclic aromatic hydrocarbons in deep-living fishes after the Deepwater Horizon oil spill, Gulf of Mexico

We measured polycyclic aromatic hydrocarbons (PAHs) in tissue (guts and muscle) of mesopelagic fishes in the Gulf of Mexico prior to, six weeks after, and one year after the oil spill (2007, 2010 and 2011). Analysis of PAHs was conducted following modified EPA method 8270D and QA/QC strict protocols. Freeze-dried fish samples undergo lipid extraction using an automated solvent extraction system with cyclohexane and dimethylchloride. Detection and quantification of PAH homologues were performed by using a gas chromatograph/mass spectrometric detector (GC/MS) in full scan mode (m/z 50-550) with splitless injections of 1µL and helium as the carrier gas. Concentrations were calculated using response factors by comparison with a known standard mixture. Overall results indicate mesopelagic fishes sampled during 2010 and 2011 contain PAH concentrations up to 10-fold higher than samples collected in 2007. The data suggest that PAHs from the Deepwater Horizon oil spill was incorporated into the mesopelagic food web of the Gulf of Mexico.