The levels of hydrocarbons in water and sediments in selected areas of the North Sea, and the assessment of their biological effect.

Abstract

In the light of increasing oil exploration and production in the northern North Sea, the Brent, Beryl and Forties oil fields, representing three different types of operation, and a number of stations between the Forties field and the Firth of Forth, were sampled to determine the levels of total (by fluorescence), alkane (by glass capillary gas chromatography) and aromatic (by gas chromatography-mass spectrometry) hydrocarbons in water and sediments. Close to the Beryl platform, where diesel-washed drill cuttings have been dumped, there was an accumulation of petrogenic hydrocarbons in the sediment, resulting in a build up of certain aryl hydrocarbons, notably the dibenzthiophenes and 3- and 4-ring aromatic compounds. In all the sediment samples analysed for aromatic hydrocarbons, relatively large amounts of 5- and 6-ring compounds were found in areas expected to be free of pollution, as well as from areas around oil platforms and from the Firth of Forth. Their source is likely to be windborne combustion products.