Dispersants Bibliography

Abstract
Recommended bioassay procedures are presented that can be routinely applied to evaluate the relative toxicity of oil, chemical dispersants, and oil-dispersant mixtures to 1) naturally occurring populations of phytoplankton, and 2)representative marine phytoplankters grown in pure culture. The methods presented, in general, represent 1) application of techniques routinely employed in the measurement of marine primary productivity, and 2) application of the Inhibitory Toxicity Test, a tentative method devised by the American Society for Testing and Materials to evaluate acute toxicity of industrial wastes to diatoms

Abstract
Recolonization of asbestos fouling plates treated variously with oil and detergents (BP 1100, BP 1002, Poly-complex all, Corexit 7664, Corexit 8666) is dependent on the season of the year. The presence of oil favors C. fissus settlement but retards algal settlement

Abstract
Mussels (Mytilus edulis L.) were exposed to North Sea crude oil, microencapsulated oil and dispersants, singly and in combination, and growth rates measured at 24-48 h intervals. Exposure to microencapsulated pure oil (2·0–2·1 mg litre-1) and to microencapsulated mixtures of oil (2·2−2·5 mg litre-1) plus 5% of the different dispersants (FINASOL OSR 5, COREXIT 9527, DISPOLENE 36 S) gave approximately the same reduction in growth rate (80-90%) within 170 h. Oil chemically dispersed with DISPOLENE 36 S and a pure oil mechanically dispersed in water were significantly less toxic. In high concentrations (2 mg litre-1) all dispersants are toxic, DISPOLENE 36 S significantly more than the others. Mussels exposed for 170 h to microencapsulated oil and to microencapsulated oil/dispersant mixtures recovered to control growth within 300 h in clean seawater, while in those given pure oil-in-water suspension, the recovery was slower. It is concluded that the toxicity of oil is mainly related to size and concentration of oil particles, while the effect of 5% dispersants added is negligible

Abstract
Authors established a method for determining rates and degrees of ultimate biodegradation of anionic surfactants. Using simple equipment, the method was used to assess biodegradability of a wide variety of agents without the need of developing specific analytical methods for each type of surfactant. The method can also be used to measure degradation rates in anaerobic and low-temperature conditions

Abstract
Chemical dispersants can be used to reduce the interfacial tension of floating oil slicks so that the oils disperse more rapidly into the water column and thus pose less of a threat to shorelines, birds, and marine mammals. The laboratory test currently specified in federal regulations to measure dispersant effectiveness is not especially easy or inexpensive, and generates a rather large quantity of oily waste water. This paper describes the results of an effort by the U.S. Environmental Protection Agency (EPA) to identify a more suitable laboratory dispersant effectiveness test. EPA evaluated three laboratory methods: the Revised Standard Dispersant Effectiveness Test currently used (and required by regulation) in the United States, the swirling flask test (developed by Environment Canada), and the IFP-dilution test (used in France and other European countries). Six test oils and three dispersants were evaluated; dispersants were applied to the oil at an average 1:10 ratio (dispersant to oil) for each of the three laboratory methods. Screening efforts were used to focus on the most appropriate oil/dispersant combination for detailed study. A screening criterion was established that required a combination that gave at least 20 percent effectiveness results. The selected combination turned out to be Prudhoe Bay crude oil (an EPA-American Petroleum Institute Standard Reference Oil) and the dispersant Corexit 9527. This combination was also most likely to be encountered in U.S. coastal waters. The EPA evaluation concluded that the three tests gave similar precision results, but that the swirling flask test was fastest, cheapest, simplest, and required least operator skill. Further, EPA is considering conducting the dispersant effectiveness test itself, rather than having data submitted by a dispersant manufacturer, and establishing an acceptability criterion (45 percent efficiency) which would have to be met before a dispersant could be placed on the Product Schedule of the National Contingency Plan (NCP). Also under consideration by EPA is a sequential testing procedure for a dispersant being placed on the schedule, whereby successful effectiveness testing would be required before toxicity testing would begin

Abstract
To better understand the properties of spilled Maui B crude oil within the context of New Zealand’s Offshore Oil Spill Contingency plans, several treatment options were explored as potential countermeasures. Among the treatment options considered were two types of chemical dispersants, one organic solvent, and two cleanup aids

Abstract
The focus of experiments were to evaluate how three dispersants affected the biodegradation and physical removal of oil, and microfauna and flora found in sediments of oil-contaminated mud flats on Spitsbergen. The microflora that responded to oil pollution in increased microbial numbers also increased in numbers after the addition of the dispersant OSR5. Despite a large increase in bacteria in sediments treated with OSR5, increases were larger when the oil was treated with Corexit 7664. The number of nematodes in sediment decreased after oil contamination, and also with additional exposure to dispersants. However, the relative percentage of bacterial feeding nematodes increased in all contaminated plots. There was a correlation between relative toxicity of oil and dispersant and the metabolically active fraction of bacteria. The biological degradation of the aliphatic hydrocarbons was most extensive in the plots treated with dispersants. Dispersants enhanced biodegradation. Corexit 7664, which resulted in the largest increase in metabolically active bacterial cell number, also enhanced biodegradation of the aliphatics. The effectiveness of dispersants in removing oil from sediments suggests that a potential exists for the development of low toxic nutrient containing chemicals that enhance both physical removal and biodegradation of oil

Abstract
A study was undertaken on the dispersion, microbial colonisation and biodegradation of chemically-dispersed weathered Forties crude oil under simulated marine conditions in laboratory microcosms. The measurements of droplet size, number and microbial colonisation were made using new techniques developed by the project team. Rapid growth of indigenous micro-organisms capable of degrading both crude oil and dispersants was observed in the presence of chemically-dispersed oil. These organisms colonised the dispersed oil and biodegraded the aliphatic and aromatic hydrocarbons. These processes were stimulated by the addition of inorganic nutrients. Some colonised droplets agglomerated into neutrally-buoyant "clusters" (l00 µm- 2 mm diameter) consisting of oil, bacteria, protozoa, and nematodes. After substantial hydrocarbon biodegradation these clusters sank to the bottom of the microcosms. No biodegradation or cluster formation was noted in "killed" controls in which biological activity had been inhibited. Different dispersants promoted microbial growth to differing extents. These results suggest that the addition of dispersants can increase the rate of oil biodegradation under natural conditions by promoting the growth of indigenous hydrocarbon-degrading bacteria, as well as increasing the surface area of oil available for microbial colonisation

Abstract
Using a continuous flow system, marine fishes, crustaceans and bivalves were exposed to surface active agents in concentrations of 100 to 0.5 ppm. LC50 values were determined in 96 hour exposures. Fish were more susceptible (0.8 to 6.5 ppm) than bivalves (5 to over 100 ppm) while crustaceans were most resistant (25 to over 100 ppm). The most active species of the three groups were more sensitive to exposure than sedentary species. Developmental stages of species were also more sensitive to exposure than were adults. The ability to recover to exposure was decreased with increased concentrations and exposure times. Stages of reaction to and sublethal effects of exposure to surface active agents are also described in this report

Abstract
The toxicities to marine animals of nine oil dispersants, three oil emulsions with Corexit and of a disperson 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 locomotor behavior 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

Abstract
The purposes of the toxicity testing done at the station are (1) to determine the relative toxicities of the different materials in standard form required by industry and government bodies, and (2) to provide predictions of the ecological consequences of pollution in marine environments. The investigations are undertaken as comparative studies of toxic materials on a wide spectrum of marine animals. represented by fish, crustaceans and bivalves. The studies involve both adult animals and developmental stages. This is of great importance as the resistance of animals varies considerably during their life-cycle, the early phases generally being the most sensitive. The acute or lethal toxicity is determined in short-term tests (96 hrs).During the tests not merely mortality and survival times are recorded but also continuous observations on effects on various biological functions which are important for the survival of the animals in their natural environment. It is from such observations that conclusions of the ecological consequences of pollution of the animal communities can be made. Chronic effects on the same biological functions are studied in long-term tests, running for several months in low concentrations corresponding to those which may occur in coastal waters. A physiological approach is also attempted by the study of the action of surface active agents on respiration, osmoregulation and accumulation in tissues and organs

Abstract
In August 1986, in conjunction with the Canadian Offshore Aerial Application Task Force (COAATF) and the Beaufort Sea Oil Spill Cooperative, Dome Petroleum Limited conducted the Beaufort Sea Dispersant Trial, with the following objectives: To determine the field effectiveness of aerially applied dispersants under Arctic conditions; To determine and test the operational parameters of “multi-hit” dispersant application; To define the logistics and cost requirements of a full-scale dispersant operation in the Arctic; To obtain a long-term (two days) record of oil slicks at sea, to determine their fate. The trial was conducted at an offshore location approximately 40 km northwest of Tuktoyaktuk, Northwest Territories, Canada. Four slicks were created, each containing 2.5 m3 (15 bbl) of Alberta Sweet mixed blend (ASMB) crude oil. One slick was left as an unsprayed control and the other three were treated with various amounts of British Petroleum’s Enersperse 700 and Exxon’s CRX-8. Effectiveness was determined by using computer-enhanced infrared and ultraviolet detectors mounted in a remote-sensing aircraft and measuring the amount of oil left on the surface of the water after each spray pass. Results of the trial are presently being analyzed. However, initial conclusions can be drawn from preliminary data analyses as follows: Successful completion of this trial had demonstrated that it is possible to conduct a full-scale, multi-hit dispersant operation using helicopters and slung buckets at remote locations in the Arctic; Single application of dispersant at dispersant/oil ratios of approximately 1:10 seem to be as effective as multi-hit applications, provided that the dispersant is given time (several hours) to work; There was an obvious difference in the initial effectiveness of the two dispersants. However, after several hours, the amounts of oil dispersed by the two products were essentially the same; Aged ASMB crude oil can be chemically dispersed even at relatively low temperatures (6º C) typical of the Beaufort Sea in summer

Abstract
It is the policy of the Federal Water Pollution Control Administration of the U.S. Department of the Interior that the relative toxicity of all chemical dispersants, both alone and in combination with oil, will be determined prior to their use for the dispersion of oil spills, and the cleaning of beaches and shore installations. Data on the relative toxicity of these materials alone--and when mixed with oil--provide the basis for the effective selection of those materials least toxic to aquatic life and for recommending or prohibiting their use. The Department takes the position that it is the responsibility of the manufacturer of such products to provide for their product alone and in oil mixture accurate tolerance limit values based on standard short-term bioassays with designated test organisms. The standard bioassay procedure used will be the one recommended by the FWPCA. This procedure is solely for the purpose of providing data which will indicate relative toxicity of dispersants and oil dispersant mixtures. These standard tests do not indicate the long-term toxicity of these materials to aquatic organisms, safe levels for the aquatic biota or for humans, nor do they constitute an endorsement of any material by the FWPCA

Abstract
The use and over-water transport of crude oils and petroleum products is increasing each year. Oil wells are increasingly being developed at locations far removed from centres of the greatest use of petroleum products, often in hazardous areas such as the continental shelves. These changes in location and transportation result in more opportunities for oil spills and losses. The number of oil spills is increasing and good housekeeping, drastic safety requirements, and effective recovery and clean-up methods must be implemented if serious pollution of the aquatic environment is to be avoided. Chemicals used for the dispersion of oil spills are much more toxic than the oil. The dispersant-oil mixtures are more toxic than the dispersant alone, and many-fold more toxic than the crude oil. In instances where it is necessary to disperse oil spills by the use of chemicals, the least toxic and most effective dispersants should be used. Relative toxicities of the various dispersants should be determined by means of standardized short-term static bioassays. Field investigations and short-term toxicity studies have demonstrated that crude and refined petroleum oils and by-products are detrimental in a number of ways to aquatic organisms and their environment. While many surveys and studies have been made to determine the location, nature, and extent of damage and the acute toxicity of crude and other petroleum oils in the aquatic environment, data are entirely lacking on the concentrations of these materials in the aquatic environment which are not harmful with long-term or continuous exposure. Although water quality standards are not feasible for oil spills, they are applicable for areas having continuous discharges of petroleum wastes. Longterm studies should be carried out to determine concentrations of petroleum oils which are not harmful to the aquatic life under conditions of long-term or continuous exposure. Studies should also be made to determine the uptake and concentration of petroleum hydrocarbons by marine organisms and to evaluate the extent of their incorporation into tissue and possible harmful effects

Abstract
Application of seawater or dispersant had no immediate impact on saving Rhizophora mangroves in oil-impacted areas. However, application of dispersed oil had no impact on mangrove mortality when compared to untreated controls

Abstract
Rhizophora managrove trees in Florida were treated with un-weathered South Louisiana crude oil by pouring the oil onto the soil and lower parts of the prop roots. Oiled trees in some plots were treated with high pressure sprays of seawater or non-ionic water-based dispersant in seawater the day after oiling to test whether oil damage could be avoided by washing away the oil. Some plots received oil dispersed with glycol ether-based dispersant to simulate the case in which a mangrove forest received oil that had been dispersed offshore. Tree deaths were scored for 30 months. The oil killed a large number of the trees whether or not they were spray washed the next day. However, plots that received oil dispersed with glycol ether-based dispersant did not show significantly more deaths than untreated control plots or those treated only with seawater or non-ionic water-based dispersant in seawater. This indicates that chemical dispersion of crude oil which is approaching mangrove forests should protect such forests from injury

Abstract
The paper describes use of dispersants in cleanup of sea oil spillage. The basic dispersant action mechanisms are described and possible limitations to their use indicated. Special attention is paid to the environmental aspect and possible harmful environmental effects of the dispersants. It is recommended that the decisions on dispersant use be made quickly but not hastily, and that they be based on informed assessment of the spillage site conditions and state. Further, the basic principles of dispersants application from ships and/or airplanes are described and a number of practical data offered

Abstract
North Atlantic seaweed was exposed to Corexit 9527 in concentrations of between 1 and 1000 ppm and at 10 ppm combined with Ekofisk or Statfjord crude oils for up to two weeks. Increased concentrations led to increased mortality, yet mortality decreased with age. No significant effects on morphology were noted

Abstract
In Hong Kong, the toxicity of oil spill dispersants was assessed in a preliminary screening test, based upon TD50 values in samples of ten fish. Later, an improved test was introduced, based upon new procedures developed in the United Kingdom and modified to suit conditions in Hong Kong. Products approved elsewhere were usually, but not always, approved in Hong Kong. Further work is needed to relate the test results to oil-spill damage in local waters

Abstract
Preliminary experiments, using the subtropical/tropical coastal and estuarine seagrasses Thalassia testudinum, Halodule wrightii, and Syringodium filiforme, were carried out to examine the effects of dispersants. Experiments exposed seagrasses in vitro to concentrations of Louisiana crude oil ranging from 7.5 to 500 milliliters (mL) in 105 mL seawater at exposure times of 5 to 100 hours (seagrass not in contact with oil slick). In other experiments, the seagrasses were exposed to the dispersant Corexit 9527, which was combined with the oil in a ratio of 1 part dispersant to 10 parts oil with the dispersant concentrations ranging from 0.75 to 50 mL in 105 mL seawater (dispersant plus oil forming a cloud of the substance in contact with seagrasses). The oil or oil with dispersant treatment was removed from the seagrasses after the designated exposure periods. Thereafter, the seagrasses were monitored for 14 days. Blade length was measured as a factor of growth. Thalassia showed the greatest tolerance to dispersant plus oil of the three species tested. It was not substantially affected by any oil concentration alone; however, when exposed to oil and dispersant, growth significantly decreased with concentrations of 125 mL oil and 12. 5 mL dispersant in 105 mL seawater at longer periods of exposure (100 hours), and also at much decreased exposure times (5 hours) for 500 mL oil and 50 mL dispersant in 105 mL sea water. Syringodium and Halodule were generally less tolerant than Thalassia, particularly to oil. For example, at 75 mL oil/105 mL sea water and an exposure of 100 hours, growth decreased significantly and mortality increased to 53 percent. Growth and mortality of Syringodium and Halodule were further affected by the addition of dispersant