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Four oil dispersants of interest for practical use in the Baltic Sea were tested as regards toxicity to animals from the littoral zone of the same area. The dispersants tested were Corexit 7664, Berol TL-188, Berol TL-198, all water-base dispersants, and BP 1100-X, an oil-base dispersant. Two species of fish, two species of bivalves and two species of crustaceans were tested. Significant differences in toxicity were found between the water-base dispersants at concentrations above 1700 ppm. Below this concentration there were no significant differences. The dispersants contain similar surfactants in similar concentrations, but differ with respect to types and amount of solvent. The observed differences at high concentrations are, therefore, argued to be connected chiefly to differences between these solvents. Differences in toxicity to different animal types were found between the water-base dispersants and the oil-base dispersants. The toxicity of Corexit 7664 was (96h LC50 approximate values): fish, 1000 ppm; bivalves, 2000 ppm; crustaceans, 10,000 ppm. The toxicity order was strikingly reversed for BP 1100-X: crustanceans, 150 ppm; bivalves, 2000 ppm; fish, 10,000 ppm. This difference in toxicity for different animal types is suggested to be connected mainly to differences in the chemical character of the outer layer of the body surface of the animals.

The toxic effects of crude oil, the dispersant, Corexit 7664, and mixtures of these on the respiration and mortality of two species of bivalve have been examined. A light Arabian crude is most toxic to one, Corexit is most toxic to the other. The susceptibility to oil of the mussel Brachidontes is also reflected in a significant depression of respiration rate at sub-lethal concentrations.

It can be calculated from the results of experiment I that exposure ofG. oceanicus to 0.2 mg/l of Aroclor 1254 solubilized in Corexit 7664 in sea water for 10 hr will produce an LT50 = 35.1 days. The data suggest that no significant biological detoxification process occurs in the animals during the experiments. However, nothing is known about the biological halflife or possible bio-transformation of PCB in animal tissues.

Crawling and respiration rates of the snail Littorina littorea are increased in the presence of Bunker C oil and decreased with brief exposure to a low toxicity dispersant (Corexit 8666) in sea water at 20 C. The addition of the dispersant to an oil:seawater mixture also decreases both crawling and respiration. Behavioral traits, such as crawling, and physiological indices, such as respiration, may be sensitive measures of sublethal effects of pollutants on organisms.

The toxicities to marine animals of nine oil dispersants, three oil emulsions with Corexit and of a dispersion of Oman crude oil, have been studied in continuous flow aquarium systems at 96-h exposures followed by a recovery period in clean sea-water. New types of dispersants were found to be less toxic than older types and oil emulsions more toxic than dispersants alone or crude oil alone. Fishes and bivalves were found most sensitive. Crustaceans were the most resistant to dispersants but very susceptible to oil emulsions. The tolerance of different species was found to be related to their mode of life, more active species being more susceptible. Delayed mortality of bivalves increased their susceptibility if the recovery period was included. Effects on locomotory behaviour of fishes and crustaceans, breathing rate of fish, valve-closure of bivalves and byssal thread formation of common mussels have been demonstrated for both dispersants and oil emulsions. The general sequence of such effects was: increased activity; successively impaired activity; immobilization; and death. Recovery is good for fish and crustaceans but poor for bivalves due to the delayed effects. Ecological consequences of dispersants and oil pollution in the marine environment are discussed.

Four chemical dispersants, Corexit 8666, Gamlen Sea Clean, G. H. Woods Degreaser-Formula 11470, and Sugee 2 were examined singly and in individual combinations with Arabian Crude Oil (1:1 ratio) at 10 and 25 C for their effects on the growth of bacteria indigenous to local marine waters, the bacterial population composition, and biodegradation of crude oil; in addition, their emulsifying capacities, at approximately 24 C, were determined. None of the dispersants used alone were toxic even at relatively high concentrations (1.25%), although Gamlen Sea Clean and G. H. Woods Degreaser-Formula 11470 did cause an increase in the lag phase which was more pronounced at 10 than at 25 C; addition of the crude oil reduced the lag phase increase. All of the dispersants used alone supported good growth of microorganisms, but qualitative population shifts were caused by the dispersant-oil combinations. The degrees of degradation of the n -alkane fraction of the crude oil varied depending upon the dispersant used. Under these test conditions, only Sugee 2, which had the poorest emulsifying capacity, promoted n -alkane degradation compared with the values obtained by using the crude oil alone.

Abstract The subject of oil spill handling represents a new area of technology that is unique in that it encompasses chemical, mechanical and biological disciplines. Within this subject the use of chemical dispersants represents a solution that can provide the most applicable approach under certain conditions. This paper defines the overall problem of oil spills and then derives the basis for the use of dispersants, as well as the conditions that justify their use. Chemical dispersants are not a panacea for the cleanup of oil spills. However, there are situations where dispersants should be used for the benefit of our natural resources; and there are also instances where they should not be used. An appreciation of the dispersing mechanism and the influence of environmental factors is necessary in order to assess the appropriate role for dispersants in the handling of oil spills. Introduction It is important at the outset of any discussion regarding oil spill dispersants to review the subject of oil spills in general in order to consider the use of dispersants in the correct perspective. The subject of oil spill handling is complex as it encompasses several engineering disciplines, as well as biological, conservationist and political interests. This paper will derive the specific area of application for dispersants and will review the pros and cons regarding their usage. At the outset, it should be outlined that the role of oil spill dispersants is one of a last resort nature since prevention of oil spills is the first consideration. In the industrial and governmental communities, the major effort has been directed toward this area. There is extensive ongoing research, for example, ranging from operational areas, e.g., collision avoidance techniques and training, to more novel approaches such as gellation of crude oil cargo to prevent release from a damaged compartment, oil-water separation devices, flocculating agents, etc. However, after a spill has occurred, physical containment and removal is the physical containment and removal is the recommended approach. This is the most complete solution to the problem. Unfortunately, the present state of the art limits the effective present state of the art limits the effective application of oil containment booms to rather quiescent conditions and they are not suitable in general for open sea conditions. As concisely summarized by Dewling, there are at least 37 different approaches to corralling and holding oil spills. Spill boom systems are available in prices ranging from $5 to $45 per foot and represent an important tool under those sea, weather and geographical conditions that permit effective deployment. There is extensive research currently underway in this area, principally funded by the U.S. Coast Guard, to principally funded by the U.S. Coast Guard, to extend the capability of spill booms.

A study has been carried out on the ichthyotoxicity effects of 14 anti-pollution products used for the dispersion of hydrocarbons in water, on the Carassius auratus . The better tolerated products are Esso Corexit 8666 and 7664; followed by Fina Sol OSR/2 and SC whilst the other products were found to contain higher ichthyotoxicity characteristics.

Last August, 3,000 tons of petrol (gasolene) was spilled in Milford Haven when the tanker, Dona Marika, ran aground. Since most documented oil spills in British waters have been of crude oil, there is considerable interest in knowing the damage caused by this spillage of a refined oil product.