LIBRARY

Abstract
Studies on the formation of emulsions were summarized, and analytical methods used to determine the final results of the emulsion breaking process were evaluated. These include visual appearance, viscosity, zero-shear-rate viscosity, elasticity, water content, and conductivity. All but the latter two are useful for determining the stability of an emulsion. The development of four new tests was reviewed. These test the effectiveness of emulsion breakers in open and closed systems and emulsion preventers in open and closed systems. Results of testing on commercial products are presented

Abstract
Effectiveness, a key issue of using dispersants, is affected by many interrelated factors. The principal factors involved are the oil composition, dispersant formulation, sea surface turbulence and dispersant quantity. Oil composition is a very strong determinant. Current dispersant formulation effectiveness correlates strongly with the amount of saturate component in the oil. The other components of the oil, the asphaltenes, resins or polars and aromatic fractions show a negative correlation with the dispersant effectiveness. Viscosity is also a predictor of dispersant effectiveness and may have an effect because it is in turn determined by oil composition. Dispersant composition is significant and interacts with oil composition. Dispersants show high effectiveness at HLB values near 10. Sea turbulence strongly affects dispersant effectiveness. Effectiveness rises with increasing turbulence to a maximum value. Effectiveness for current commercial dispersants is gaussian around a peak salinity value. Peak effectiveness is achieved at very high dispersant quantities - at a ratio of 1:5, dispersant-to-oil volume. Dispersant effectiveness for those oils tested and under the conditions measured, is approximately logarithmic with dispersant quantity and will reach about 50% of its peak value at a dispersant to oil ratio of about 1:20 and near zero at a ratio of about 1:50

Abstract
The effects of varying the rotational speed (energy), settling time and shaking time were measured on the laboratory dispersant test; the swirling flask test. Dispersant effectiveness onset between 100 and 150 rpm, indicating a threshold process for dispersion. The dispersant effectiveness increased slowly after the onset with increasing rotational speed. The settling time changes effectiveness very much between 5 and 80 min. Change was especially rapid at 5 min. The amount of shaking time did not change the effectiveness significantly. This is also indicative of a threshold dispersion process

Abstract
Authors report on the use of a modified chromatographic method for measuring dispersant effectiveness on various crude oils in the laboratory. For this investigation, ASMB, Federated, Pitas Point, South Louisiana, Thevenard, Udang, Bunker C, Hondo, Santa Clara, Jet Fuel, Diesel, and North Slope oils were used. Results indicate that the modified method increased accuracy of dispersant effectiveness for very light and very heavy ends of the oil spectrum

Abstract
Authors report on a modified GC method for measuring dispersant effectiveness in the laboratory. The method resulted in improved accuracy of determining effectiveness, which showed dispersants having lower effectiveness on lighter oils and higher effectiveness on heavier oils than previously found in laboratory tests

Abstract
This paper is a review of five types of chemical treatments for oil spills. Gelling agents change oil to a solid or semi-solid form, but are not widely used because of the large amount of agent required. Elastol, a recovery improvement agent, has been tested and proven to function well under a variety of conditions. A number of oil-in-water emulsion preventers and breakers have been proposed, but none is commercially available. A demoussifier developed by Environment Canada has been recently tested and found to be effective. Surface washing agents contain surfactants and quantitative results on a number of these agents are presented. Dispersants contain surfactants which are intended to break up oil into small droplets in the water column. No undisputed documentation exists to show that dispersants have been very effective in field situations, but analytical means to measure field effectiveness are poor. Laboratory effectiveness results are presented for a number of oils and dispersants. The main concern with treating agents is their effectiveness, and this is often dependent on molecular size and type. Oil has many molecular types and sizes, thus rendering treatment much les than totally effective

Abstract
We have reviewed the laboratory testing of the chemical and natural dispersion of oil, noting the weaknesses of the Mackay test and comparing it to other methods. Results of both chemical and natural dispersion tests show that anomalous test results are produced in the Mackay apparatus at 0° C. This is attributed to preferential viscous shearing when the oil viscosity is 30 to 200 centistokes (cs). A new test uses a small swirling flask. Dispersant effectiveness results for ten oils from the Mackay, Labofina, and swirling flask tests were compared and the correlation found to be low. Results from the new swirling flask test correlate well with physical property data, especially viscosity. Each laboratory test produces somewhat unique results, and no way has yet been found to determine which test most accurately represents reality

Abstract
Laboratory tests and apparatus for oil spill dispersant effectiveness were the subject of the present study. A review of previous work shows that test results from different apparatus are not highly correlated, and often the rank of effectiveness is also not correlated. The effect of two experimental parameters--settling time and oil-to water ratio--are examined in this study and found to be very important in determining final effectiveness value. Four apparatus--the swirling flask, the flowing column, the Labofina, and the Mackay--are used with 3 dispersants and 16 oils to examine effectiveness values when the oil-to-water ratio is the same (1: 1,200) and when the settling time is maintained at the same value (10 minutes) in all apparatus. The effectiveness values resulting from the four devices are nearly identical after values from the more energetic devices are corrected for natural dispersion. Our conclusions are that the most important parameters of laboratory dispersant testing are settling time and oil-to-water ratio. Energy is less important than previously thought and is important only to the extent that when high energy is applied to an oil-dispersant system, dispersion is increased by an amount related to the oil's natural dispersibility

Abstract
Laboratory tests of oil spill dispersant effectiveness are used around the world to select dispersants for application to specific oils. These tests are presumed, by some, to represent real sea conditions and to provide the user with a result that is representative if not identical to a real dispersant application at sea. A number of tests have been developed over the years. At this time, the two most widely used tests are the Mackay test, otherwise known as the Mackay-Nadeau-Steelman (MNS) test, and the Labofina test, otherwise known as the Warren Springs or rotating flask test. The Mackay test employs a high velocity air stream to energize 6 L of water, whereas the Labofina test uses rotation of a separatory funnel with 250 mL of water. Both tests apply a large amount of energy to the oil/water system. This paper compares test results from these apparatus with those from two lesser known devices, the oscillating hoop and the swirling flask. Both devices are relatively new, and protocols for their use have not been finalized. The oscillating hoop apparatus uses a hoop which is moved up and down at the water surface. The concentric waves serve both to energize the oil in the hoop and to contain it. Thirty-five litres of water are used in this test. The swirling flask test makes use of a 125-mL Erlenmeyer flask. The flask is rotated using a standard chemical/biological shaker to produce a swirling motion in the contents. The results obtained using all 4 apparatus with a number of oils and dispersants are presented. A total of 121 oil/dispersant combinations were tested in the 4 apparatus. The correlation of numeric values between the Mackay, Labofina, oscillating hoop, and swirling flask is low. The correlation of effectiveness ranking is also poor. An oil that disperses more readily than another, according to one test, is less readily dispersable according to one or more of the other tests. Similarly, a dispersant that is more effective by one test is less effective by another. The results from the oscillating hoop correlate poorly with all other test results. Specific tests were also conducted to ascertain the effect of settling or rising time (the time the oil-in-water mixture is allowed to sit unagitated before a sample is taken). Longer settling times alter the oscillating hoop test results dramatically, improve the correlation for results with different apparatus and enhance correlation with physical data such as viscosity.differences in the effectiveness results are still present. Results show that all the high energy tests (the Mackay, the Labofina and the oscillating hoop) produce unique dispersant effectiveness results and those correlate poorly with the physical properties of the oil

Abstract
Laboratory effectiveness tests have been developed for four classes of oil spill treating agents: solidifiers, demulsifying agents, surface-washing agents and dispersants. Several treating agent products in these four categories have been tested for effectiveness. The aquatic toxicity of these agents is an important factor and has been measured for many products. These results are presented. Solidifiers or gelling agents solidify oil. Test results show that solidifiers require between 16% and 200% of agent by weight compared to the oil. De-emulsifying agents or emulsion breakers prevent the formation of or break water-in-oil emulsions. Surfactant-containing materials are of two types, surface-washing agents and dispersants. Testing has shown that effectiveness is orthogonal for these two types of treating agents. Tests of surface washing agents show that only a few agents have effectiveness of 25 to 55%, where this is defined as the percentage of oil removed from a test surface. Dispersant effectiveness results using the "swirling flask" test are reported. Heavy oils show effectiveness value of about 1%, medium crudes of about 10%, light crude oils of about 30% and very light oils of about 90%

Abstract
Dispersant effectiveness tests are reviewed. Studies have been conducted of the variances among several standard regulatory tests. Three main causes of differences have been identified, oil-to-water ratio, settling time and energy. Energy can be partially compensated for in high energy tests by correcting for natural dispersion. With this correction and with high oil-to-water ratios and a settling time of at least 10 minutes, five apparatuses yield very similar results for a variety of oils and dispersants. Recent studies into the energy variation of dispersant tests show that the energy level varies in many apparatuses. The repeatability of energy levels in apparatus is largely responsible for the variation in dispersant effectiveness values in certain apparatus. Studies of analytical procedures show that traditional extraction and analysis methods cause a bias to results. Methods to overcome these difficulties are presented

Abstract
Female F. grandis were intubated with a single dose of one of a number of Aroclor formulations with and without fuel oil. The PCB with fuel oil and fuel oil alone caused considerable inhibition of fin regeneration from 14 days onwards. In further experiments the oil dispersant BP 1100X was given singly and in combination with Aroclor 1268 and fuel oil. BP 1100X with fuel oil inhibited fin regeneration for the first 21 days. Some differences were seen according to the time of year at which the experiment was carried out. Aroclor 1268 with fuel oil in the autumn resulted in stimulation rather than the inhibition of regeneration seen in spring. The results highlight the complexity of problems with compounds that interact and the seasonal differences in the effects observed

Abstract
This paper describes the role of dispersants in oil spill response, the benefits of use versus natural dispersion of oil, and the evolution of dispersants from environmentally toxic and haphazardly applied to modern, safer formulas and application techniques that have very small environmental impact. The Sea Empress spill is highlighted as evidence of the evolution of dispersants and their beneficial use in specific cases

Abstract
Modern oil spill dispersant formulations are concentrated blends of surface active agents (surfactants) in a solvent carrier system. The surfactants are effective for lowering the interfacial tension of the oil slick and promoting and stabilizing oil-in-water dispersions. The solvent system has 2 key functions: 1) reduce viscosity of the surfactant blend to allow efficient dispersant application, and 2) promote mixing and diffusion of the surfactant blend into the oil film. A more detailed description than previously given in the literature is proposed to explain the mechanism of chemical dispersion and illustrate how the surfactant is delivered by the solvent to the oil-water interface. Laboratory data are presented which demonstrate the variability in dispersing effectiveness due to different solvent composition, particularly for viscous and emulsified test oils with viscosities up to 20,500 mPa·s. Other advantages of improved solvent components can include reduced evaporative losses during spraying, lower marine toxicity and reduced protective equipment requirements. Through this improved understanding of the role of the solvent, dispersants which are more effective over a wider range of oil types are being developed

Abstract
Recent data with modern demulsifying oil spill dispersant (Corexit 9500) challenge old viscosity limits for the window of opportunity for dispersant use on viscous oils and emulsions. The demulsification capability of the dispersant to reverse and significantly reduce the viscosity of emulsified oil was demonstrated. This demulsification effect is a prelude to dispersion of the oil. In addition, high effectiveness was demonstrated on no. 6 fuel oil fractions with viscosities over 40,000 cP, well beyond previous indicated limits

Abstract
Significant effort continues to be directed at improving, and ultimately correlating, laboratory and field testing of dispersant effectiveness on oil spills at sea. This technology, which is complicated by the formation of water-in-oil emulsions, was recently advanced as part of the successful 1997 AEA North Sea field trial with Alaska North Slope crude oil and Corexit 9500 dispersant. Prior to the field trial, standardized and slightly modified laboratory test methods were used to better simulate field conditions and predict dispersant performance. Simplified field tests for emulsion stability and dispersibility were also carried out to provide a qualitative linkage between the laboratory and field results. The field trial effectiveness data obtained after two days weathering at sea confirmed the extended "window of opportunity" for this demulsifying dispersant, as the oil dispersed rapidly and completely after treatment. For the first time, a direct comparison of laboratory effectiveness test data could also be made with an extensive set of field data on highly weathered emulsified oil. It was concluded that an extended-time MNS test provided the closest match with field observations on the performance of the demulsifying dispersant. Recommendations for future laboratory and field tests are proposed to further advance the technology

Abstract
In this study, Corexit 9500 was tested on heavy bunker fuel oil (IFO-38) and analyzed using the SINTEF methodology. Dispersability evaluations were undertaken on the oil, covering a wide range of properties found in different laboratory effectiveness procedures (MNS, WSL, IFP, EXDET). Finally, a meso-scale flume test was run to confirm the laboratory methodology. Viscosity, influenced by sea temperatures and weathering, was an important factor in the dispersability of the heavy oil. Time after spill, especially after 24 h, slowed the dispersion process, and required higher dispersant treatment rates

Abstract
Chemical beach cleaners can facilitate cleanups of oiled shorelines by improving the efficiency of washing with water. The improvement is a result of reduced adhesion of the oil coating, which makes it easier to remove from shoreline surfaces, thereby reducing washing time and lowering the temperature of the wash water needed to clean a given area. The criteria established for use of chemical beach cleaners in the Exxon Valdez spill cleanup included demonstrating enhanced cleaning with low levels of toxicity to marine biota and with minimal oil dispersion. Since no commercially available products satisfactorily met the criteria for use in Alaska, a new product, Corexit 9580, was specifically developed in response to this need. This paper describes the successful development of this chemical, including both laboratory testing and field testing in Prince William Sound

Abstract
A critical need currently exists for standard laboratory procedures for evaluating demulsifiers over the range of applications encountered in oil spill response. The procedures should be flexible enough to generate emulsions that are representative of those encountered at various time during a spill situation, and the applications should cover emulsion inhibition, breaking emulsion slicks at sea, and breaking recovered emulsions. Two laboratory test procedures are proposed. The procedures have different mixing energy and treating conditions, but each has the desirable feature of utilizing the same apparatus to generate the emulsion and to test the demulsifer. One procedure, called the wrist-action shaker emulsion test (WRASET), utilizes a standard laboratory apparatus, and is applicable for emulsion inhibition and for simulating at-sea application of demulsifers. A second procedure, called the rotating flask emulsion test (ROFLET), can also be used for a range of applications and is applicable for treating emulsions during oil recovery operations. Data from each of the two laboratory emulsion tests are used to demonstrate their features and to provide guidance on their use. An important implication of this work is that laboratory tests currently used to evaluate the effectiveness of dispersants to break up emulsions at sea need to be modified to provide time for the emulsions to be first broken by the dispersant

Abstract
A simple test, using embryos of the grass shrimp Palaemonetes pugio, was employed to determine the toxicity of two commercial oil dispersants (Corexit 7664 and Corexit 9527) and toxicity of the water soluble fraction of Number 2 fuel oil (WSFoil) prepared with and without the addition of the dispersants. Tests revealed P. pugio embryos were similar to previously measured life stages in their sensitivity to WSFoil prepared without dispersants. They were approximately ten times more sensitive to water soluble fractions of dispersed oil, which may have been due to the increases in total hydrocarbons (measured analytically). Both temperature and salinity of the sea water affected toxicity of WSF prepared with dispersants, the most obvious effect being earlier onset of mortalities at higher temperatures. Differences observed in the onset of mortalities with WSF prepared with and without dispersants implicated egg-casing permeability as a factor in toxicity. The shrimp embryo toxicity test, described here for the first time, exhibited highly significant results, outstanding reproducibility and virtually 100% response within a narrow time interval

Abstract
The use of dispersants to control marine oil spills is common practice in many areas throughout the world. In the United States, the use of dispersants has been discouraged up to this time by federal regulations. A Task Force was appointed by the American Petroleum Institute to make recommendations on the utilization of dispersants based on studies of current information on dispersants and mechanical recovery equipment. The use of dispersants should be encouraged where it is justified. The Task Force believes that the use of dispersants can at times be the most effective and biologically sound method of controlling offshore oil spills. For this reason, we would like to see the National Contingency Plan revised so that the responsible On-Scene Coordinator (OSC) has more authority over the use of dispersants. The OSC should be able to decide to use dispersants to control offshore oil spills that threaten to move into sensitive environmental or commercial areas. If the plan is revised, then oil spill cleanup organizations would be encouraged to have stocks of low toxicity dispersants, and suitable spraying systems

Abstract
New formulations of dispersant products are less toxic and more effective than ever before. These new products, coupled with more detailed application techniques, have brought about safer and more cost-effective use of these substances. Dispersants, as well as surface collecting agents, biological additives, and a new miscellaneous category of products that includes gelling agents, elastomers, solidifying agents, and polymers can be used alone or in combination for more effective oil spill cleanup. New testing protocols being developed by the U.S. Environmental Protection Agency and new product developments during the past three years are discussed. The National Contingency Plan Subpart H Product Schedule, the number of products on the schedule, what it means for a product to be listed on this schedule, and how to get a product listed on the schedule also are described

Abstract
Work is in progress by ASTM Subcommittee F20.13 on Treatment on a series of guidelines covering the use of dispersants in nonsaline environments. These environments include freshwater ponds, lakes, and streams, as well as land. The guidelines are to be patterned after those produced by an earlier task group of the same committee covering saline environments. This paper describes what has been accomplished thus far. Participation by those interested, whether an ASTM member or not, is welcomed

Abstract
A marine oil-degrading population grown at 8°C showed a selective sensitivity regarding utilization of compounds in Prudhoe Bay oil in the presence of the dispersant Corexit 9527. The response was dependent on the nitrogen and phosphate levels of the medium and on the concentration of dispersant used. In the presence of a nitrogen-phosphate solution and a Corexit 9527-crude oil substrate, degradation of the n-alkanes of the saturate fraction was temporarily retarded in proportion to the concentration of Corexit 9527 present. This retardation was overcome with extended incubation time. In the absence of nitrogen-phosphate supplementation, the effect of Corexit 9527 was pronounced, retarding n-alkane degradation even with extended incubation time. Corexit 9527 had less effect on the degradation of the aromatic fraction and may indeed be stimulatory in the case of select compounds. The development and testing of dispersants containing nitrogen and phosphate is recommended

Abstract
Samples from a previous study observing the effects of Corexit 9527 on microbial degradation of aromatics and saturates in crude oil were reanalyzed by capillary gas chromotography with a sulfur-specific detector. The results shown an inhibitory effect on degradation of sulfur heterocycles (such as benzothiophenes and dibenzothiophenes), dependent upon dispersant concentration and nutrient supplementation

Abstract
Capillary gas chromatography (CGC) and C14-radiometric techniques were used to investigate the effects of 15 oil dispersants on microbial degradation of Norman Wells crude oil. Other biochemical processes, including phosphatase, methane production, and both aerobic and anaerobic nitrogen fixation, were studied with selected dispersants. Several dispersants showed no inhibitory effects on microbial biodegradation under laboratory conditions. Other dispersants were found to be toxic or inhibited degradation. Phosphatase activity was stimulated by two of the four dispersants tested in the presence of crude oil. All four dispersants stimulated phosphatase activity when no oil was present. Three dispersants stimulated aerobic N2 fixation. However, anaerobic stimulation occurred when dispersants were present in high concentrations. Only one dispersant stimulated methane production in anaerobic sediments

Abstract
In laboratory studies, the effects associated with water-to-air transfer of anionic detergents sprayed on oil slicks were investigated. Dissolved anionic detergents increased the production of marine aerosol. Detergents concentrated and enriched up to 100 times their concentration with respect to seawater. Additionally, mm-thick oil slicks reduced the amount of spray and also the amount of surfactant transferred to aerosol state. Detergent concentrations and type of oil was thought to affect the amount transferred to aerosol

Abstract
This work is dealing with the sublethal effects of six detergents on the life cycle of the Polychaete Capitella capitata. This species is characteristic of polluted bottom areas. Specimens are obtained from natural populations and studied in the laboratory. The tested detergents, issued from the oil industry, are three anionic (alkylarylsulfonate, lauric alcohol sulfate, fatty alcohol oxyalkyl ester) and three non-ionic (oxyethylene oxypropylene amine, polyethylene glycol ester, oxyethylene alcohol). The short duration of the life cycle of C. capitata permits to propose a method for qualitative and quantitative evaluations of these pollutants' sublethal effects. The results show that the disturbing considered effects depend on the concentrations and stage of the life cycle. When the concentration increases, the length of the different phases increases and one observes a decrease of the number of juveniles is observed. The more sensible stages are the maturation of the ovarian tissue and ovocytes and the metamorphosis