Dispersants Bibliography

Abstract
Mesoscale testing was undertaken with Corexit 9500 on Hibernia crude in cold winter conditions. Results indicate that chemical dispersion would be effective on Hibernia in cold conditions until the crude had evaporated to about 9-10% in volume. After this, the oil begins to solidify, making dispersion extremely difficult

Abstract
Research experiments were completed to determine the viability of using chemical dispersants on two crude oils in very cold water conditions. Tests were completed at Ohmsett (the National Oil Spill Response Facility in Leonardo, New Jersey) in late February and early March of 2002. Ohmsett is a large outdoor, above-ground concrete tank (203 m long by 20 m wide by 3.4 m deep) filled with 9.84 million gallons of salt water. The tank has a wave-generating paddle, a wave-dissipating beach, and mobile bridges that transport equipment over its surface. A refrigeration unit was installed to ensure that the water was kept at near freezing temperatures during the entire test program. A total of twelve large-scale tests were completed. Corexit 9500 and Corexit 9527 were applied to fresh and weathered Hibernia and Alaska North Slope crude oils, on cold water (-0.5 to 2.4 °C), at dispersant-to-oil ratios (DORs) ranging from 1:14 to 1:81. The average wave amplitude for the tests ranged between 16.5 and 22.5 cm and the average wave period was between 1.7 and 1.9 seconds. The effectiveness of the dispersant in each test was documented through extensive video records and by measurement of the residual oil remaining within the containment boom at the end of each test. The results clearly show that both dispersants were effective in dispersing the two crude oils tested in cold-water conditions

Abstract
Two important questions facing oil spill responders, planners, and researchers are: 1) What is the limiting viscosity of oil for dispersant use; and 2) How well do results from dispersant effectiveness tests performed in laboratory apparatus and experimental wave tanks reflect dispersant performance at sea? In order to begin addressing these questions, a series of at-sea dispersant effectiveness trials were completed in the UK in the summer of 2003 to estimate the viscosity of spilled fuel oils that limits dispersant effectiveness under conditions of moderate sea states (Beaufort Sea states 2 to 4). Two well-characterized marine fuel oils (IFO 180 and IFO 380) with viscosities of 2000 and 7000 cP were spilled, sprayed with dispersants, and dispersant effectiveness was assessed. Several types of dispersants and a range of dispersant dosages were tested. These tests are currently being repeated using a variety of laboratory and mesoscale dispersant apparatus to determine how well the results of these various test methods correlate with dispersant performance at sea. Dispersant effectiveness tests in the SL Ross wave tank, using the identical oils and dispersants from the UK offshore trial, were the focus of this study. The goal of the work was to determine if the dispersant effectiveness test results from this tank are similar to results measured in the offshore. The tank testing indicated that the IFO 180 oil (viscosity of 2000 cP at the test temperature of 16 °C) is readily dispersible with Corexit 9500 and Superdispersant 25 when applied at dispersant-to-oil ratios (DORs) exceeding 1:75 for for Corexit 9500 and 1:50 for Superdispersant 25. the IFO 380 fuel oil (viscosity of 7000 cP at the test temperature of 16 °C) was 53% dispersed when treated with Corexit 9500 at a DOR of 1:30. The IFO 380 oil can be dispersed, but larger quantities of dispersant must be applied to achieve significant results. The tank test dispersant effectiveness results measured for the Corexit 9500 dispersant were similar to the UK field test trends for the IFO 180 oil and were somewhat higher than the field results for the IFO 380 oil. The tank test results for Superdispersant 25 were slightly higher than the field trial trends for the IFO 180 oil and slightly lower for the IFO 380 oil. The limited data available for the Agma DR379 dispersant suggests that the tank test results were similar to the offshore trial results for the IFO 180 oil and lower for the IFO 380 oil. In general, the SL Ross tank test results matched the trends in the offshore results reasonably well. Variations in sea states and DORs during the sea trials, insufficient data points for direct comparison and the lack of resolution in the 4-point visual assessment system do not permit a more definitive comparison of the results of the test programs

Abstract
Growth of the green alga Enteromorpha linza (L) was increased when the wetting agent "Tween 60" was added to the nutrient solution. This growth-promoting effect is then presumed to depend on the lowered surface tension

Abstract
Researchers studied the biodegradation of FINASOL OSR 51, in the presence of the biologic activators BIOLEN IG 30 and BIOLEN IC 10. BIOLEN IC 10 and BIOLEN IG 30 degraded the total and anionic dispersants present in the FINASOL OSR 51 at ambient (23°C) and control temperatures (20°C). Maximum degradation efficiency of the total ionic dispersants was obtained with BIOLEN IC 10 after 26 days and in the presence of the biodegradation accelerator INIPOL EAP 22 at 23°C, obtaining a degradation rate of 95.72%. For anionic dispersants, a 95.88% degradation rate was obtained after 28 days using BIOLEN IC 10 and in the presence of INIPOL EAP 22 at 23°C. Researchers found no significant differences in the degradation percentage for the total ionic dispersants after 26 days, when using BIOLEN IC 10 or BIOLEN IG 30 at 23°C and in the presence of INIPOL EAP 22 (95.72% for BIOELN IC vs. 94.47% for BIOLEN IG 30). Similarly, there were no significant differences for the anionic dispersants degradation between the two biological activators at 23°C and in the presence of INIPOL EAP 22, obtaining a 95.88% after 28 days when degradation process occurs with BIOLEN IC 10 and 94.38% for the same conditions with BIOLEN IG 30

Abstract
An aged hydrocarbon mixture from an accidental spill gave investigators the opportunity to observe degradation rates using biological amendments. FINASOL OSR 51 dispersant was also present and researchers studied degradation rates associated with this material. from these experiments, investigators were able to determine the degradation process constant, biological oxygen demand, biological final demand, the biological stabilization constant, as well as the stabilization constant for the degradation process

Abstract
FINASOL OSR 51 was used in biodegradation tests in the presence of a biological activator (BIOLEN IG 30). Nutrients and oligoelements were added to artificially increase degradation rates. Kinetic and correlation coefficients were determined at ambient temperature and 20°C for up to 26 days after the initial and weekly addition of BIOLEN IG 30

Abstract
Dispersants used during the Torrey Canyon cleanup operations were tested, focusing on efficiency and toxicity of the chemicals used during the disaster. The method of assessing dispersants known as the swirling beaker test is described in the appendix of this report

Abstract
Chemical agents for treating oil pollution have been described variously as “detergents,” “dispersants,” “emulsifying agents,” “solvent emulsifiers,” and so on. In this paper, however, the word “dispersant” will be used to cover materials. The basic way in which dispersants work is that they change the interfacial properties of oil and water, enabling an oil layer to be broken up by agitation into very small droplets which may be readily dispersed in the body of the sea. The ways in which dispersants are applied, and the available techniques for supplying agitation to the treated oil, differ greatly depending on whether or not the oil has come ashore. Very often too, dispersants, which are effective in dealing with floating oil, are completely useless for cleaning beaches, although the reverse is seldom if ever true. There is a need, therefore, for separate methods of assessing the efficiencies of dispersants in combating oil at sea and on shore. It is also necessary to know the effect of dispersant treatment on marine life, so that in alleviating the evil of oil pollution one does not cause unnecessary damage to marine flora and fauna. It is beyond the scope of this paper to discuss toxicity testing of dispersants. This subject has been covered by Dr. R.G.J. Shelton of the Shellfish Laboratory of the UK Ministry of Agriculture, Fisheries and Food. Rather, it is my purpose to describe what has been done by the Institute of Petroleum (IP) Working Party on “Detergents and their Application” to derive meaningful rules for determining which dispersants should be used for cleaning up oil pollution in various circumstances

Abstract
Toxicity and temporal changes in toxicity of freshwater-marsh-microcosms containing South Louisiana Crude (SLC) or diesel fuel and treated with a cleaner or dispersant, were investigated using Chironomus tentans, Daphnia pulex, and Oryzias latipes. Bioassays used microcosm water (for D. pulex and O. latipes) or soil slurry (for C. tentans) taken 1,7, 31, and 186 days after treatment. SLC was less toxic than diesel, chemical additives enhanced oil toxicity, the dispersant was more toxic than the cleaner, and toxicities were greatly reduced by day 186. Toxicities were higher in the bioassay with the benthic species than in those with the two water-column species. A separate experiment showed that C. tentans’ sensitivity was intermediate to that of Tubifex tubifex and Hyallela azteca. Freshwater organisms, especially benthic invertebrates, thus appear seriously effected by oil under the worst-case-scenario of our microcosms. Moreover, the cleaner and dispersant tested were poor response options under those conditions

Abstract
Four oil spill dispersants when used alone (0.1% V/V) or in combination with Saudi Arabian Crude (0.5% V/V) were non-toxic to Arthrobacter simplex and Candida tropicalis. At a higher concentration of 0.6% (V/V) only D2 was found to be toxic to both the organisms. Dispersant treatment did not increase the bio-degradation of crude oils except D3 in the presence of Bombay High crude oil

Abstract
After 18 months of planning, the Baffin Island Oil Spill (BIOS) Project was formally initiated in March 1980. This project marks a major new initiative in oil spill countermeasures development for Canada 's northern frontiers. The primary objectives of this internationally funded project are (1) to determine if the use of chemical dispersants in the Arctic nearshore will reduce or increase the environmental effects of spilled oil, (2) to assess the fate of oil, and (3) to compare the relative effectiveness of other shoreline protection and cleanup techniques. This paper outlines the background and scope of the 4-year project and provides an overview of the first field season's results. Highlighted are the preliminary oil discharges, which took place in August 1980, and which marked the start of studies on the long-term fate of oil on Arctic beaches. In addition, the results of the baseline physical, chemical, and biological studies are presented. The physical program included detailed oceanographic, meteorological, and geomorphological studies. The chemical program determined the background hydrocarbon concentrations in the sediments, the water column, and the tissue of selected macrobenthic species; and also the environmental chemistry of the study area. The biological program characterized the macrobenthic flora and fauna and the micro-organisms that are potentially capable of biodegrading the oil. The physical, chemical, and toxicological properties of the oil were measured in laboratories and in the field. The ramifications of these results on the design of the oil spills scheduled for 1981 are discussed

Abstract
The Baffin Island Oil Spill (BIOS) Project, formally begun in March 1980, now is entering the fourth and final year of the planned field work. The primary objectives of this internationally funded project are to: (1) determine if the use of chemical dispersants in the arctic nearshore will reduce or increase the environmental effects of spilled oil, (2) assess the fate of oil, and (3) compare the relative effectiveness of other shoreline protection and cleanup techniques. This paper provides an overview of studies sponsored by the BIOS Project during the first three field seasons. Highlighted are the major oil releases which involved a total of 40 cubic meters of medium gravity crude oil. In addition, the preliminary results of the pre- and post-spill physical, chemical, and biological studies are presented. The physical program studies predicted the proper time and location for the oil releases and monitored the subsequent physical fate and behavior of the oil. The chemical program studies monitored the pre- and post-spill hydrocarbon levels in the water, sediments, and tissue of selected macrobenthic species, and also the environmental chemistry of the study area. The biological program studies to date have characterized the macrobenthic flora and fauna, the microorganisms, and the shorter-term effects of the oil releases on the subtidal biota. The potential ramifications of the BIOS Project's results on future oil spill countermeasure strategies are discussed

Abstract
This presentation summarizes a study of currently used laboratory methods for evaluating oil spill treating agents. Work was performed under contract to the American Petroleum Institute. Treating agents were classified as dispersants, sinking agents, sorbents, combustion promoters, biodegradants, gelling agents, and beach cleaners. The mechanisms and chemical reactions controlling the field application of each type of agent were defined. Parameters critical to the evaluation of both the effectiveness and toxicity of each type of agent were thereby identified. Present methods of laboratory measurement were compiled and reviewed for the adequacy of parameter control as well as the appropriateness of the variables measured. It was found that no existing standardized tests are capable of reproducibly and accurately measuring the effectiveness or toxicity of any oil spill treating agent. Some tests, notably those for dispersants, are amenable to improvement such that reliable laboratory methods will result through improved mechanical equipment, temperature control, exposure conditions, agitation level, reagent standardization, and selection of test biota. The study concluded with a delineation of procedures, equipment, and material specifications for laboratory effectiveness and toxicity measurement. These are modified versions of existing methods and it was recommended that they be verified by an appropriate laboratory program

Abstract
Despite recent major improvements in the efficiency of low toxicity oil dispersants, the dispersing capacity of available vessels remains inadequate to deal with a spill of more than 10,000 tons in European waters. In the event of an emergency on a larger scale, it may be necessary to immobilize the oil by sinking it, using sand. Experiments to test the toxic effects of sunken oil masses on benthic animals have been reported previously. This paper describes experiments to assess the possibility of damage to marine organisms from the sinking agents used. The results show that toxic effects are likely to result from the wetting agents and solvents used in the sand sink method of treating oil spills. The risk of harmful effects from this source can be reduced by careful selection of the wetting agent and solvent. 'Armac T' in ethylene glycol is the least toxic combination of those tested

Abstract
Under the Dumping at Sea Act 1974 the use of oil slick dispersants requires a licence from the Ministry of Agriculture, Fisheries and Food in England and Wales. These licences are issued or refused on the basis of tests to assess the toxicity of the dispersant when used at sea or on beaches. This paper describes the rationale behind the development of the two toxicity tests used, together with the test methods adopted and the results of the tests

Abstract
This paper discusses the adoption of the Swirling Flask Test (SFT) by California as the standard method for evaluating the effectiveness of oil spill treatment products. Differences between the procedures, as adopted by California, and the EPA’s existing SFT method, are discussed

Abstract
The effect of receiving water salinity on the effectiveness of two oil dispersants, Corexits® 9527 and 9500, was investigated using a recently implemented modified version of the Swirling Flask efficacy test. The dispersants were tested with ten different oils, representing a wide range of physical-chemical properties. Test salinities ranged from 0 to 35 ppt, with temperature held constant at 15°C. Results showed Corexit 9500 to be generally more effective on most of the dispersible oils at most salinities, but performance of both products was significantly affected by salinity. Both dispersants performed best at salinities above 25 ppt, with Corexit 9500 maintaining its effectiveness over a fairly wide range of salinities. Correlations between dispersant effectiveness and various oil physical/chemical properties were highly variable

Abstract
The effects of 'Corexit 7664', an oil dispersant, alone and in combination with oil in sand columns were determined by oxygen uptake, 14C uptake, and chlorophyll analysis. 'Corexit' was observed to have no obvious deleterious effects within the experimental system under the conditions of periodic and continuous additions ranging from 5 x 102 ppm to 105 ppm and in combination with Kuwait crude oil (1.2 kg oil/m2 to 0.12 kg ‘Corexit’/m2). No change was observed in chlorophyll or 14C uptake. Heightened oxygen uptake was noted for continuous addition of 'Corexit' (0.060 ml. O2 hr-1 cm-1), for the oil control (0.090 ml. O2 hr-1 cm-1), and for oil plus 'Corexit' (0.059 ml. O2 hr-1 cm-1). Caloric content of the oil and oxygen uptake indicated and extended degradation period

Abstract
A major consideration in determining the desirability of using dispersants to clear oilspills is the extent to which the dispersant alters the exposure of water organisms to the oil. To assess the toxicity and environmental risk it is necessary to calculate the distribution of specific hydrocarbons between the oil phase, the aqueous phase and the vapour phase during a toxicity test. Three factors are involved in these tests, the effect of the dissolved hydrocarbon, the effect of dispersed oil particles and the effect of the dispersant chemical, each being dependent on different factors of concentration, size, etc. A set of equations has been derived to permit calculation of the partition of a hydrocarbon, between the various phases, to be used in the design of toxicity tests

Abstract
The toxicity of fresh and weathered crude oils and chemical dispersants to Daphnia magna has been investigated using a novel system which eliminates evaporative losses and maintains oil in emulsified form at 5 and 20°C. Biossays were conducted for dispersants alone, for water soluble fractions of crude oils obtained at various water/oil ratios, for physical dispersions of crude oils and for chemical dispersions of crude oils. The results suggest that generally the dispersed oil particles are the primary sources of toxicity, with the dissolved oil and dispersants contributing relatively little toxicity. The toxicity of the oil particles appears to be influenced by particle size. A mathematical model has been prepared and calibrated using these data, and gives a satisfactory representation of the observed toxicity of chemically dispersed oil

Abstract
To minimize the ecological impact of oil at sea, dispersants are used to spread the spill across a large amount of water and thus make hydrocarbon levels low enough to be sublethal. Such an objective demands two correlative conditions: (1) that an oil-in-water emulsion can be obtained by adding the dispersant and (2) that rapid dilution conditions are provided by a downward motion of oil droplets and wind-induced velocity shear between surface and subsurface. In September 1981, two 6-m3 slicks in the Mediterranean Sea were treated by two concentrated dispersants. More than 1500 samples were taken at different depths during several hours following treatment and were analyzed by a differential method to measure separately oil and dispersant. Direct measures were also recorded by a continuous flow of water through a nephelometer and a spectrofluorometer. Despite apparently complete emulsification of the slick, the most efficient dispersant did not preclude some of the oil from resurfacing 6 h after treatment. The short-term fate of dispersed oil was therefore under the control of the sea conditions, which limit dilution processes. Because any laboratory test in closed vessel cannot duplicate dilution factors, a new approach was developed to measure simultaneously the rate of dispersion and the behavior of test marine animals submitted to variable concentrations of potentially toxic substances during the flow of dispersed oil through a continuous system

Abstract
This paper describes a dynamic flow-through test developed by the Institut Français du Pétrole for the assessment of dispersant efficiency, as well as dispersant toxicity. The procedure can be used to examine the effect of dispersant oil ratios and physical constraints on dispersant effectiveness

Abstract
Controlling the Amoco Cadiz spill and cleaning the sea and the coast of Brittany were made highly difficult by rough sea conditions and the location of the grounding. The rapid formation of “chocolate mousse” limited severely the efficiency of the different techniques used. At sea, restrictions on the use of dispersants led to use of both sinking and absorbing agents, including an experimental product, rubber powder. On the coast, several types of chemicals were used or tried; emulsion breakers, sorbents, dispersants, and biodegrading products. Practical examples were given of how some of these products could help the cleanup operations on beaches, rocks, and piers and the handling of oil, polluted sand, and debris. The use of sorbents demonstrated that, despite the additional cost, this approach could be helpful if adequate operational techniques for such use were available

Abstract
This report describes a procedure for measuring dispersant efficiency by measuring the amount of chemically dispersed oils that affix to different sediments. Mass balance of oils and solids was obtained by quantitative analysis of settled, resurfaced, and washed out oil fractions

Abstract
This report recounts 30 offshore trials in six groupings between 1979 to 1985 off the French Mediterranean and Brittany coasts. Several types of dispersants were used, applied by ship (using different spraying systems), helicopter (with underslung bucket) and airplane (Canadair CL 215). To find the most optimal method, various techniques were employed. These included the use of a variable flow-rate system to spray neat concentrates from ships, and methods of directing dispersing craft from sea and air for enhanced coverage. Effectiveness of Dispersant use was distinguished between primary effects (dilution of smallest oil droplets) and secondary effects (increased long-term natural dissemination). Limiting factors included sea-surface energy, subsurface currents and dispersant/oil ratios

Abstract
Six campaigns of dispersant offshore trials were conducted from 1979 to 1985 off the French Mediterranean and Brittany coasts. Altogether, 30 slicks were treated with several dispersants applied from ships by different spraying systems, from helicopters equipped with an underslung bucket, and from a Canadair CL 215 aircraft. Despite the difficulty of getting a mass balance of dispersed oil on the basis of oil concentration measurements and remote sensing techniques, the trials resulted in identifying the different effects of dispersants (short term dispersion of oil, delayed dissemination) and the limiting parameters (minimum energy of sea surface, high dispersant/oil ratio needed, negative herding effect). Different techniques were tested in order to optimize the application of dispersants in different situations: use of variable flow-rate system to spray neat concentrates from ships, methods of operating ships and aircraft to reach a selective distribution of dispersant and get good coverage of slicks

Abstract
Some misunderstanding has arisen from evidence of deleterious effects of oil dispersion, leading to the conclusion that such a treatment is more dangerous than the pollution itself. In fact, the main objective is to promote the speed of degradation by parcelling of oil, the droplets becoming widespread and bursting at the ocean surface to form films which quickly will disintegrate under microbial actions. With new dispersant formulations, the hydrocarbon pollutants will tend to separate out from sea water so that living organisms would not be injured in the comparatively clean water below. Meanwhile, by its chemical composition, the dispersant will bring nutrients to the medium and, moreover, will remain within the oil phase

Abstract
14 different samples of special oil dispersing products were examined with regard to the toxicity they cause in organisms of freshwater, brackish water and seawater. From the experiments resulted that concerning their toxic effect a great number of the compds are to be grouped into class III of the classification according to Hellmann and Knopp, which means that up to the highest examined conc of 200 mg/l no toxicity exists. A specially low degree of toxicity was found in compd VIII. These results have shown that products of the groups fatty-acid-polyglycolic-ester are of practical importance

Abstract
The fate of an experimental oil pollution of intertidal sediments in a sheltered beach of North Brittany (France) has been investigated over a 16-month period. Chemical treatments were applied to two of the three contaminated plots by pre-mixing oil respectively with dispersant and biodegrading agents. The physico-chemical and bacteriological characteristics of the polluted areas were followed with the purpose of identifying the limiting parameters for oil microbial degradation and the effect of treatment. The concentration of hydrocarbons in the oiled sediments did not change significantly during the experimental period. Spectrofluorimetric and chromatographic data showed that the main evolution of oil concerns the degradation of n-alkanes and the removal of light aromatics. Biodegradation of hydrocarbons occurred at a measurable rate only during the warm seasons (average temperature 18± 2°C) causing after sixteen months the disappearance of more than 80% of the n-alkanes fraction independently of the pollution sediment level and the chemical treatment of the experimental plots. However, the biodegradation of n-alkanes proceeded during the first months, at different rates, inversely depending on oil content in the collected samples. The main limiting factor is dissolved oxygen according to the fact that spilled oil was located at 3-5cm depth in a poorly oxygenated zone characterized by low redox potential. Nutrients were not a limiting factor probably due to domestic and agricultural inputs in this area. A marked bacterial growth was observed two weeks after the oil spill with a relative increase in hydrocarbon degrading bacteria with respect to total heterotrophs. Degradation rates, based on C14 n-hexadecane experiments, seem to follow the same way than specific bacterial counts (plate technique). Specific bacteria are always high at the end of our 16 months' field experimentation. In the laboratory as well as in the field experiments, the same behaviour of untreated and chemically treated oil was observed in partially anaerobic sediment

Abstract
The distribution and environmental fate of petroleum hydrocarbons introduced into the nearshore environment of Cape Hatt, Baffin Island, Canada, during two controlled experimental discharges of a Venezuelan (Lagomedio) crude oil have been studied. An analytical program based on a combination of ultraviolet/fluorescence studies, high resolution gas chromatography, and computer-assisted gas chromatographic mass spectrometry has been used to examine several hundred oil, seawater, sediment, sediment trap, surface floc, and benthic animal (seven species) samples to determine the distribution, transport, and weathering of oil spilled in two scenarios: as untreated oil on the surface and as chemically dispersed oil discharged below the surface. Conclusions are drawn about the weathering of oil in the two scenarios, transport of low and high molecular weight hydrocarbons into the water column and their persistence, the sedimentation of oil, the incorporation of oil into the sediment via sedimentation on to the surface floc and direct penetration of the sediment/water interface, and the uptake and depuration of untreated and chemically dispersed oils by seven species of filter feeders and deposit feeders in the subtidal benthos