Pyrogenic Polycyclic Aromatic Hydrocarbons in Oil Burn Residues

Recent field trials and tanker accidents have shown that burning crude oil at sea can be an effective response for marine oil spills. Nevertheless, there is concern that the residue may have elevated levels of potentially toxic pyrogenic polycyclic aromatic hydrocarbons. We have simulated a marine oil slick burn using Statfjord crude oil, a light paraffinic North Sea crude. The burn was over seawater to an efficiency of 85%, typical of efficiencies achieved in the field. We have used gas chromatography coupled with mass spectrometry to examine the polycyclic aromatic hydrocarbons present in the crude oil burn residue and used hopane as a conserved internal marker in the oil to allow us to quantify the generation of pyrogenic compounds. The concentrations of several of the pyrogenic aromatic compounds were somewhat enriched in the residue, but these increases were outweighed by the mass of oil consumed in the burn. In situ burning substantially reduced the total amount of polycyclic aromatic hydrocarbons left on the water surface after the spill.