Environmental effects of offshore oil production



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Analytical methodology for the quantitation of alkanes, aromatic hydrocarbons, and sulfur was developed and was applied to the study of the environmental effects of offshore oil production. Completely deuteriated alkanes are separated from the corresponding unlabelled alkanes and serve as internal standards for the quantitation of environmental alkanes by gas chromatography alone. This technique provided a detection limit of 50 ng/1 for hydrocarbons in seawater and 100 ng/g for hydrocarbons in sediments and in biological samples. The deuteriated analogs of aromatic hydrocarbons required the mass spectrometer for the gas chromatographic detector to distinguish them from the compounds being measured. With the application of single ion monitoring of the molecular ions, the detection limit for hydrocarbons in seawater, sediments and biota is 1 ng/g. The quantitation of sulfur, using an internal standard of sulfur-34, also required the mass spectrometer as the gas chromatographic detector. Multiple ion monitoring of m/e 64, 66, 68 resulted in a detection limit of 50 ng/g for sulfur-32 in sediments. The Buccaneer oil and gas field, operated by the Shell Oil Company, has been in production since 1960. The field was chosen because of its isolation and the small amount of oil spilled (totaling less than 1000 1) during the history of the field, as well as the age of the field which has allowed time for the establishment of a dynamic marine community. [...]