Dispersants Bibliography

Abstract
This paper describes the development of a simple remote sensing system for the detection of oil on water. Signals from sensors operating in the ultraviolet and infrared are combined in a computer-based image processing system to produce information on the area of thick and thin portions of the slick, from which the effectiveness of dispersants can be calculated. The design parameters, the selection of sensors, and the integration of these sensor signals into a user friendly display is discussed. The use of this UV/IR system in field oil spill experiments and in an actual spill situation is described

Abstract
The effects of three oil spill chemicals (Corexit 9600, 9550, and 7664) on cuticular structure and function in the sandbar willow Salix interior were assessed from direct observations of the leaf surface, using scanning electron microscopy, and from measurements of water loss through transpiration. Rates of CO2 exchange in the light and dark were also measured. Although the Corexits coated the leaf surfaces, wax plates (crystals) associated with the cuticle were not visibly altered. The dispersants did not increase rates of evaporative water loss. Rates of net CO2 assimilation in the light, however, were reduced by 54, 63, and 94% 1 h after contact with Corexit 7664, 9550, and 9600, respectively. Measurements of surface contact angles and observations on the movement of dye - dispersant mixtures indicated that the rapid inhibition of CO2 assimilation resulted from the spontaneous infiltration of stomata by the dispersants and direct action on the internal tissues of the leaf. Rates of dark respiration were initially unaffected but decreased after 1 day. Further reductions in rates of CO2 exchange were observed over the first 4 days (associated with extensive leaf chlorosis and necrosis): then the rates increased following new tissue growth. Although the dispersants are potent contact poisons, damage to the protective cuticle in Salix interior does not appear to be a major contributing factor to their toxicity

Abstract
The effects of three oil spill dispersants (Corexit 9600, 9550 and 7664) on carbon fixation by the fruticose lichen Cladina mitis were examined in order to provide insights into the potential risks associated with dispersant use in and around freshwater systems. Cladina is a common plant of northern freshwater shoreline communities. Treatments with the undiluted dispersants inhibited rates of carbon fixation by 60% to 80% and bleached portions of the thalli when applied at doses less than 10 mg g-1 dry weight (approximately 2·5 mg cm-2 on an aerial basis). Since the recommended field application rates for the dispersants range from 0·2 to 3 mg cm-2, there is a distinct possibility that misapplication (direct spraying) may be detrimental to populations of Cladina. However, the inhibitory effects were not lethal in all cases and partial recovery of the lichens was noted within 3 weeks after treatment. The potential impact of dispersant use in freshwater systems on the shoreline plant communities is discussed in the light of our findings

Abstract
To determine the effects of surfactant exposure on reproduction in mussels, Mytilus edulis L. were placed in water with low surfactant concentrations (.5 to 1.5 ppm) over a 5-month period. When mature, spawning capabilities of the mussels were examined. Fertilization was not affected in low concentrations of surfactant, but inhibited or delayed larval development was noted. This appeared to be concentration-dependent in short-term doses of surfactants. Gametes were more sensitive in long-term surfactant-exposed tests than those monitored in the long-term control

Abstract
The uptake and elimination of a labelled surfactant, the nonionic nonylphenol ethoxylate, was studied in cod (Gadus morrhua L.) exposed to a concentration of 5 ppm. The amount of labelled surfactant was analyzed by the scintillation counting method in various tissues from the fish. A penetration especially through the gills, but also some intestinal resorption was found. Eight hours from start a steady state condition was obtained. High concentrations were found especially in gall bladder and liver. The elimination process in clean sea water was quite rapid and after 24 h the residues

Abstract
The Italian National regulations on oil-dispersants use (D.D. 23 December 2002) require for these products to pass several laboratory screenings before they can be applied in oil-spill clean-up. Although legislation recommend the use of the American mysid shrimp Americamysis bahia, for laboratory toxicity testing, there is growing interest in employing local marine crustacean species more representative than A. bahia, in quantifying the risk of significant harm to Mediterranean ecosystems. The aim of this study (in the framework of the National Project 'Taxa Project', supported by the Italian Ministry for the Environment and Territory) is to improve new specific bioassays for assessing acute or sublethal responses to oil dispersants using the larval stages of the sessile crustacean Balanus amphitrite. The bioassays were standardized using sodium dodecyl sulphate (SDS) as toxic reference compound. Results of acute toxicity (48 h LC50, 7.49 mg l-1) and behavioural tests (7 d EC50, 7.79 mg l-1) with barnacle larvae showed that their susceptibility to SDS could be comparable with that of A. bahia (96 h LC50; 6.6 mg l-1). Therefore, a B. amphitrite bioassay could be proposed to replace the A. bahia bioassay in a standardized toxicological screening of new products for oil-pollution remediation technologies in the Mediterranean Sea

Abstract
The combined effects of concentrations of an oil dispersant, Chemserve OSE-DH, temperature, and exposure time, on the viability of pretreated gametes of the sea urchin Parechinus angulosus, is reported. The importance of the influence of temperature and prefertilization exposure on gamete viability is shown. Temperature fluctuations affect sperm viability to a marked extent with little effect being evident where ova are concerned. Increased exposure to Chemserve OSE-DH has a cumulative, deleterious effect on ova viability. The interactive effects of the variables appear to magnify the overall deterioration of gametes subjected to the stressed conditions

Abstract
Clean Coastal Waters, Inc. (CCW) is an oil industry funded Oil Spill Removal Organization (OSRO) whose capabilities have been classified by both the U.S. Coast Guard and the State of California. The current method of rating response equipment does not provide for insightful management of the organization's mechanical recovery equipment. CCW has therefore utilized the National Oceanic and Atmospheric Administration's (NOAA) "Mechanical Equipment CalculatorTM" (MEC) to provide an alternative assessment of CCW's oil spill recovery capability. The MEC provides a more realistic view of spill recovery capability and it allows for manipulation of recovery system components to maximize their effectiveness. A major objective of this assessment was to examine each system's performance using realistic oil slick conditions. Three representative oil slick conditions, ranging from light to heavy concentrations, were selected as input for the computerized simulation and evaluation of each recovery system's potential performance. The relative contribution of each system was examined under real-world conditions including actual times for notification, mobilization, transit, recovery and offloading of recovered oil and water. A secondary objective of the assessment was to investigate methods by which each system's recovery rate could be enhanced while operating in open water with widespread slick conditions representing as little as a barrel of oil per acre (i.e., with average oil thicknesses of a few hundredths of a millimeter). This investigation indicated the need for several changes to the CCW equipment inventory in order to maximize system performance. Clean Coastal Waters is currently experimenting with real-world application of these enhancements and has already incorporated several important modifications into its recovery systems. Such modifications include: the matching of onboard pumps with expected oil encounter rates; the adjustment of system swaths to better utilize potential recovery capabilities; and, the inclusion of multiple, secondary storage units at key locations for improved overall performance. The third objective of the assessment was to evaluate the utility and effectiveness of the MEC. The MEC was determined to be an effective tool for characterization, evaluation and management of response capabilities. CCW will continue to use the MEC to assist its Member Companies in managing recovery systems during training, exercises, and actual spill response activities

Abstract
Researchers studied the effects of Corexit 9527 and Corexit/crude oil mixtures on glucose uptake and mineralization rates in microbial populations found in Arctic and Subarctic marine waters and sediments. In almost all samples (149 water and 95 sediment) tested, decreased glucose uptake rates were observed when Corexit was present at 15 or 50 ppm, and depressed uptake rates were noted with 1 ppm of Corexit. 12 ppm was the mean concentration at which Corexit depressed glucose uptake by 50%. Corexit’s effects were more evident on pelagic, rather than benthic, microbes

Abstract
Growing acceptance of dispersants as a front line oil spill response tool is due in large part to the availability of reliable scientific effectiveness measurements. This paper examines the procedures known as specialized monitoring of advanced response technologies (smart) that determine if dispersant chemicals are having the desired effect of causing small droplet formation and dispersal in the water column. Response decision makers will benefit from the discussion of monitoring protocols, the visual and empirical indicators of dispersion, and the equipment used to derive this data. Proof of smart feasibility and utility is provided in the form of case histories, data, and photographs from recent exercises and two actual dispersant response operations

Abstract
Acute lethal bioassays using semistatic conditions were conducted to assess the toxicity of crude oil, dispersant, and dispersed oil using the amphipod Allorchestes compressa as a test species. Sublethal bioassays (suppression of burying behavior over 24 hours of exposure) were conducted for these toxicants using the marine sand snail Polinices conicus. Both lethal and sublethal bioassays were also carried out for two reference toxicants: sodium dodecyl sulphate (SDS) and zinc sulphate. Mean (n = 4) acute 96-hour LC50(SE) values for A compressa exposed to Corexit 9527, dispersed crude oil, and water-accommodated fractions (WAF) of crude oil were 3.03 mg/L (0.05), 16.2mg/L (2.8), and 311,000 mg/L (5760), respectively, EC50 (SE) concentrations for P. conicus exposed to Corexit 9527, dispersed crude oil, and WAF of crude oil (30 minutes’ exposure) were 50.2 mg/L (2.10), 65.4 mg/L (1.95), and 190,000 mg/L (5600), respectively. These sublethal EC50’s were reduced to 33.8 mg/L (0.7) for Corexit 9527, 26.3 mg/L (1.3) for dispersed crude oil, and 43,8000 mg/L (1400) for WAF of crude oil following a 24 hour exposure period

Abstract
Acute 96-h LC50 values of the water-accommodated fraction (WAF) of crude oil, dispersants (Corexit 9500 and Corexit 9527) and dispersed oil combinations were determined in semi-static bioassays with seawater, using the amphipod Allorchestes compressa (Dana). Sub-lethal bioassays (suppression of burying behaviour over 30 min and 24 h exposure) were also conducted for these toxicants, using the marine sand snail Polinices conicus (Lamarck) as the test organism. Sodium dodecyl sulphate (SDS) and zinc sulphate were used as reference toxicants and identical bioassays were conducted using these compounds. The mean (n = 4) 96 h LC50 (SE) values for WAF of crude oil, Corexit 9527, Corexit 9500, dispersed oil (9527) and dispersed oil (9500) were 311,000 ppm (5760), 3.03 ppm (0.05), 3.48 ppm (0.03), 16.2 ppm (2.8) and 14.8 ppm (0.8), respectively. The mean (n = 4) 30 min EC50 (SE) values were 190,000 ppm (5600), 50.2 ppm (2.1), 58.9 ppm (3.1), 65.4 ppm (1.95) and 56.3 ppm (1.9) for WAF of crude oil, Corexit 9527, Corexit 9500, dispersed oil (9527) and dispersed oil (9500), respectively. These values reduced to 43,800 ppm (1400), 33.8 ppm (0.7), 42.3 ppm (1.1), 26.3 ppm (1.3) and 24.9 ppm (1.4) after 24 h exposure for WAF of crude oil, Corexit 9527, Corexit 9500, dispersed oil (9527) and dispersed oil (9500), respectively. These LC50 and EC50 values indicated that dispersed oil combinations were significantly more toxic to these organisms than WAF of crude oil. Caution should thus be used when deciding to use chemical dispersion as a remedial action for an oil spill in temperate inshore Australian waters

Abstract
Using semistatic bioassays, Ghost shrimp Palaemon serenus and larval Australian bass Macquaria novemaculeata were used to establish acute 96 h LC50 values of the WAF of crude oil, Corexit 9500 and 9527, and dispersant/oil mixtures in seawater. The nominal mean (n=4) LC50 standard error (SE) values for WAFs of toxicants from shrimp bioassays were 258,000 ppm (13,000) for crude oil, 49.4 ppm (6.4) for Corexit 9527, 83.1 ppm (5.8) for Corexit 9500, 8.1 ppm (0.3) for oil/Corexit 9527, and 3.6 ppm (0.3) for oil/Corexit 9500. The nominal mean (n=4) LC50 SE amounts of WAFs from the fish larval bioassays were 465,000 ppm (16,000) for crude oil, 14.3 ppm (0.9) for Corexit 9527, 19.8 ppm (1.6) for Corexit 9500, 28.5 ppm (1.4) for oil/Corexit 9527, and 14.1 ppm (2.6) for oil/Corexit 9500. Results indicate that the WAF of oil/dispersant mixtures had significantly higher toxicities than the WAF of crude alone. Total petroleum hydrocarbon uptake measured in shrimp showed a correlation to exposure concentrations, and dispersant presence made oil more available for shrimp

Abstract
A massive oil spill affected approximately 215 km of coastline as a result of the grounding and subsequent explosion of the supertanker Urquiola at the entrance to the harbour at La Coruna, Spain, on 12 May 1976. A total of 99-100 000 tons of Persian Gulf crude oil was lost, most of which burned, but an estimated 25-30,000 tons washed ashore. Over 2,000 tons of dispersants were applied to the oil at sea. Land-based clean-up and control methods were largely inadequate to combat the spread of oil, and were ineffective at preventing large scale environmental damage

Abstract
It is essential to understand the factors influencing the distribution, damage, and long-term persistence of oil spills to adequately plan for, and apply appropriate cleanup techniques. Based on the study of two massive spills, and two smaller spills under ice conditions, these factors are 1) wind stress and water currents, 2) beach activity and grain size, 3) tidal stage, 4) wave energy, 5) oil quantity and composition, and 6) ice effects, where applicable. Coastal environments vary significantly in terms of resultant damage from spilled oil. Subsequent cleanup by dispersants or mechanical means should be planned accordingly. Considering the aforementioned factors, as well as initial biological effects, a classification of coastal environments in terms of potential oil spill damage has been developed. In order of increasing vulnerability, these environments are 1) exposed, steeply dipping or cliffed rocky shores; 2) eroding wave-cut platforms; 3) fine-sand beaches; 4) coarse sand beaches; 5) exposed, compacted tidal flats; 6) mixed sand and gravel beaches; 7) gravel beaches; 8) sheltered rocky coasts; 9) sheltered tidal flats; and 10) salt marshes and mangroves. This classification can be used to delineate oil-sensitive environments as part of an overall contingency plan to limit damage during an oil spill

Abstract
The paper reviews some of the experimental work carried out at the Biologische Anstalt Helgoland. In each of the experiments described, the results demonstrated some of the limitations in using the LD50 method for determining toxicity. These include use of laboratory organisms, use of adults, and the inability to determine the influence of longterm sublethal concentrations on behaviour, survival, reproduction and community structure. Bacterial populations of Serratia marinorubra in freshly sampled seawater were shown to be far more sensitive to 3 different emulsifiers than laboratory cultures of these organisms. Wastewater from a titanium factory was shown to have a detrimental effect at relatively low concentrations on unialgal cultures of the phytoplanktonic organisms Ceratium furca and Prorcoentrum micans. "Red mud", a waste product of aluminium factories had a damaging effect on the food chain of marine fish, and on the juvenile life stages of the herring Clupea harengus. Herring larvae were also shown to be extremely sensitive to very low concentrations of oil emulsions

Abstract
Gaps exist in knowledge about sedimentation and transport of weathered oil, natural degradation rates, and the flow of hydrocarbons through the food web. Relatively little is known about the influence of oil and dispersants upon complex ecosystems. The often mentioned suspicion of increased cancer probability in humans due to seafood contaminated by hydrocarbons has not been substantiated; in fact, it seems unlikely that such an effect exists. By far the greatest uncertaintly about potential oil impact concerns possible negative effects of hydrocarbons on chemical communication mechanisms between organisms. Intensive studies of behavior scientists working with concentrations far below the toxic level are needed in fisheries biology, zoology and botany. Most cases of oil contamination known thus far have been limited in space and time; the oil has turned out to be degradable by natural processes. Such oil pollution neither endangers nor considerably impairs the future of mankind. In future research, more than anything else, objective critical evaluation and careful quantification are needed

Abstract
When spilled in the environment, especially in coastal systems such as estuaries, oil frequently interacts with fine mineral particles to form aggregates. This phenomenon may be enhanced in the case of chemical dispersion and influence the behavior and fate of the pollutant in the environment. Understanding this process will help decide whether chemical dispersion is a good oil clean-up option in a particular environment. This study investigated the formation of oil-mineral aggregates (OMA) when the oil was chemically dispersed, focusing on the size distribution of these structures. Results of laboratory experiments show that aggregate size is correlated to its relative composition in oil and clay, and that for a given concentration of mineral, the average size presents a maximum. Other highlights include the influence of oil type and salinity on the clay concentration corresponding to maximum size. The behavior of a particular oil as OMA depends on the size and buoyancy of its aggregates which will vary with the local of salinity, suspended mineral load and hydrodynamics conditions

Abstract
When spilled at sea, many oils are known to form emulsions. These emulsions are often of high water content and viscosity, poorly dispersible, hard to recover and to pump, and are likely to remain as a persistent pollutant that may come ashore. To avoid these difficulties, demulsifiers have been used, either to inhibit emulsion formation or to break emulsions that have already been created. CEDRE has studied the efficiency of several demulsifiers on the rate of emulsion formation and on the dispersibility of emulsified oils of different types. This study was conducted in three stages. Firstly, a study of the rate and extent of emulsification was conducted in the laboratory. Secondly, the effect of demulsifiers was studied in floating mesocosms placed in a harbor. The demulsifiers did not succeed in totally preventing emulsion formation, but they inhibited the degree of emulsification of the oils for some time. Thirdly, the dispersibility of weathered oils was studied in laboratory using the IFP and WSL test methods and then in the Polludrome where the effects of different treatment strategies combining demulsifiers and dispersants applications were assessed

Abstract
A two-stage study was carried out to determine to effect of oil-fines interaction on chemically dispersed oil. Results of laboratory investigations were compared with results from Cedre’s testing flume run at different current speeds. Maximum rates of oil trapped in clay were related to dispersant effectiveness. Analysis of oil in the water column found that aggregates settled only at low current speeds. After clay/oil mixtures formed sediment layers, a 15 cm/second current rate was necessary to resuspend the material

Abstract
A two-step study was performed to investigate the possibility of using modern dispersants on high viscosity oil and water-in-oil emulsions. For this study, the IFP and WSL methods were used, and comparisons of results from both tests were reported. The results of the WSL method found that, depending on dispersant used, 50% efficiency was achieved on oils with viscosities up to 10,000 to 20,000 cs. The IFP results, which employed the Polludrome, reported lower efficiencies on viscous oils, indicating that laboratory methods may tend to overestimate dispersion efficiency

Abstract
The water-soluble oil dispersant Esso Corexit 9527 has earlier been found to interfere, even in low concentrations, with fertilization and development. Further studies of the effect on sea urchin spermatozoa demonstrate that Corexit 9527 gives negative biological effects in concentrations down to 0.0003 ppm

Abstract
The effects of Russian crude oil and some emulsifiers on the eggs and larvae of northern pike (Esox lucius) in brackish water (salinity 5.8 ppt were studied experimentally. Neste A (emulsifier), Talestol (surfactant), crude oil dispersed with Neste A, and contact with floating oil increased the mortality of eggs during developments. Dissolved frations of oil had no effect on the mortality rate. All substances increased the occurrence of abnormal larvae. Neste A, Talestol, and dispersed oil were toxic to pike larvae; dissolved fractions, Corexit 8666, and BP 1100 had no acute effects. High temps increased the toxicity of emulsifiers. The resistance of pike larvae varied greatly at different stages of development

Abstract
Dispersants have now become a viable and preapproved response tool in the Gulf of Mexico; however, there are currently no standard procedures or terminology for an actual dispersant operation under the incident command system. A dispersant model for an actual dispersant operation has been developed by the authors with the assistance of large industry group. This model, which can apply to all types of dispersant operations, describes responsibilities and on-scene coordination of persons involved in a dispersant operation. Specifically, the model clearly identifies the various positions and responsibilities for such an operation. Benefits of the model include better coordination, improved communications, and reduced conflict between industry and government agencies; these benefits result in quicker response times, which are critical to dispersant operations

Abstract
Crawling and respiration rates of L. 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 degrees C. The addition of the dispersant to an oil: seawater mixture also decreases both crawling and respiration. Behavioural traits, such as crawling, and physiological indices, such as respiration, may be sensitive measures of sublethal effects of pollutants on organisms

Abstract
Researchers assessed whether the addition of nitrogen and phosphorus enhanced biodegradation of crude oil chemically dispersed with Corexit® 9500. Nitrogen was found to increase biodegradation of alkanes and PAH, while phosphorus only enhanced the biodegradation of alkanes. Concentrations of dispersed oil did not impact biodegradation rates or the density of degrading microbes. Attenuation factors for N concentrations associated with biodegradation rates were 2.32 mg N L-1 for alkanes and 1.69 mg N L-1 for PAHs. The attenuation factor for alkanes related to biodegradation rates was increased with the addition of phosphorus (1.42 mg N L-1), while no change was noted for PAHs