Weathering of oil

Ekofisk crude oil (250 L) was exposed to weathering in Nov. 1977 contained in an oil boom on Trondheimsfjorden. Meteorologic and hydrographic data were recorded. Immediately after release of the oil, concentrations of up to 190 ppm of gas were measured 50 cm above the slick. In the water 20 cm below the oil, several parts per million of hydrocarbons was detected. Evaporation and solution of the oil was studied over a period of one month by gas chromatography. The loss of oil during this period was approximately 40%. Trials conducted with a polyvinyl chloride skimmer to study the adhesive properties of the oil showed that the amount of oil recoverable by this method varied between 0.03 and 0.13 ml/sq cm. Microbiological investigations, phytoplankton growth, and growth rate measurements of Ascophyllum nodosum in oil/water mixtures also were made. The total number of bacteria in the polluted water increased by approximately 1000 times during 2 days following release of the oil. The phytoplankton were only slightly affected (75 cm below the slick), though A. nodosum showed a clear reduction in growth rate.