Environmental photooxidation of dibenzothiophenes following the Amoco Cadiz oil spill

Photooxidation products of dibenzothiophenes (sulfur containing petroleum heteroaromatic hydrocarbons) were characterized in an oil slick sample obtained from a field location following the AMOCO CADIZ oil spill. The same oxidation products were formed in the laboratory by the photooxidation of a medium Arabian crude oil which contained the identical precursor hydrocarbons. Analytical techniques included fractionation by liquid/solid chromatography and characterization using high resolution gas chromatography-mass spectrometry. To the best of the author's knowledge, this represents the first reported instance for the formation of photooxidation products following an actual oil spill. A comparison of the quantities of various oxidation products was carried out by quantitative mass spectrometry using extracted ion current profiles of dibenzothiophenes and their corresponding sulfoxides. The geochemical and physiological implications of such photooxidation processes are also discussed.