Introduction

During this century the demand for petroleum as a source of energy and as primary raw material for the chemical industry has resulted in an increase in world production to about 3500 million metric tons per year (Energy Information Administration, 1992). It has been estimated that approximately 0.1%, 35 million tons, enters the sea per annum (National Research Council, 1985). A great part of the oil pollution problem results from the fact that the major oil-producing countries are not the major oil consumers. It follows that massive movements of petroleum have to be made from areas of high production to those of high consumption. Although the large crude oil spills following tanker accidents (e.g., Table 4.1) receive the most public attention, tanker accidents represent only a small fraction, about one million tons, of the total input. By comparison, oil input to the sea from natural sources, principally seeps, is about 0.5 million tons annually. The major sources of oil pollution are municipal and industrial wastes and runoffs, leaks in pipelines and storage tanks, and discharge of dirty ballast and bilge waters. Since the residence time of hydrocarbons in the sea is decades or centuries (Button et al., 1992), dissolved hydrocarbons circulate in the deep oceans, thereby constituting a global problem.

The toxicity of petroleum hydrocarbons to microorganisms, plants, animals and humans is well established. In fact, many bioassays for petroleum pollution have been developed which depend on low concentrations (5–100mg/l) of crude oil or petroleum fractions killing or inhibiting the growth of microalgae and juvenile forms of marine animals.