Abstracts of Oral Presentations Session 001: Oil Spill Response and Mitigation Agents Evaluation of Chemical Countermeasures as Potential Response Options P. Doelling NOAA, Houston, TX When responding to an oil spill, it is important to consider all “tools in the toolbox,” including alternative response technologies. Chemical countermeasures such as dispersants, surface washing agents, and bioremediation products which are listed in Subpart J are evaluated on an incident specific basis. In certain situations, they may require approval by the Regional Response Team (RRT). The discussion presented will describe factors generally considered in such evaluations, and include case study examples. Emissions from Crude Oil- and Crude Oil-Dispersant Contaminated Seawaters due to Breaking Waves N. Afshar-Mohajer, C. Li, A. M. Rule, J. Katz, K. Koehler Johns Hopkins University, Baltimore, MD Crude oil spill incidents generate a variety of occupational, ecological and environmental issues. Application of chemical dispersants to oil contaminated water drastically reduces the oil-seawater interfacial tension, thereby decreasing the size of droplets, and enhancing their dispersion. However, little is known about how the use of dispersants impact the generation of aerosolized droplets as well as the concentration and composition of emitted gases during breakup of oil slicks by waves on the ocean surface. The purpose of this study, was to measure the size distribution of aerosols in the 10 nm to 20 µm diameter range, the total particle-bound polycyclic aromatic hydrocarbons (pPAH) and the total volatile organic compounds (TVOC) above breaking waves impacting oil slicks. Chemical speciation of VOCs was conducted to identify toxic constituents. Air samples were collected as plunging breaking waves of varying strength were generated periodically for extended periods in a wave tank (6 ⨯ 0.3 ⨯ 0.6 m) containing seawater. Waves impinged on clean water as well as 0.5 mm thick slicks containing crude oil and crude-oil pre-mixed with Corexit 9500A dispersant. The number concentration of aerosolized droplets smaller than 20 nm was 30 and 102 times larger when dispersant was used compared to clean water, for droplet diameter of 12.6 nm at kinetic wave energies of 0.007 and 0.01 m2/s3, respectively. Concentration of pPAH was 152 ng/m3 with dispersant and 269 ng/m3 without. In contrast to the nano-droplets, the average concentration of TVOC and individual VOCs measured with the crude oil-dispersant mixture was about 3 times lower than that of crude oil without dispersant. Further investigation is needed to determine mechanisms preventing VOC evaporation when dispersants are involved. Health concerns and risks associated with inhalation of oil and dispersant nano-droplets along with their atmospheric transport should also be investigated. Analysis of the Community Structure of Planktonic Protozoa Following Exposure to Physically and Chemically Dispersed Crude Oil S. Cosgrove, M. Moison, T. Severin, E. J. Buskey University of Texas Marine Science Institute, Port Aransas, TX Planktonic protozoa are an essential part of the marine food web serving as consumers of phytoplankton species and as prey of larger zooplankton. Little is known regarding the effect of crude 2 *Student presenter oil spills and the use of dispersant on this important group. As plankton diversity can be greatly reduced in areas of oil spill, our aim was to determine the effect of Louisiana light sweet crude oil and dispersant Corexit 9500A on the community structure of protozoan groups during 7 day mesocosm experiments. Using crude oil concentrations of 5ppm and 10ppm with a dispersant to oil ratio of 1:20, we examined the survival, mortality and potential recovery rates of protozoan species within conditions which best reflect the natural environment. Alterations in community diversity and species richness were observed most in the 10ppm dispersed oil treatment, including the greatest decrease in cell density for all dinoflagellate and tintinnid ciliate species. This lead to dominance by the ciliate groups’ oligiotrichea and spirotrichaea, with Strombidium sp. representing 24% and Euplotes sp. 47% of the total observed protozoan population by day 7. Less alteration in community diversity was observed in the 5ppm dispersed oil treatment, and the recovery of Strombidium sp. and Mesodinium sp. was observed by day 5 after initial suppression. Of the 9 dinoflagellates genera quantified over the sampling period, Ceratium sp. and Prorocentrum sp. demonstrated the most tolerance to the 5ppm treatment, with increased cell densities of 2000 cells L-1 and 500 cells L-1 respectively, following 5 days of exposure. These results show certain protozoan groups exhibit a higher level of tolerance and potential for recovery following exposure to chemically dispersed crude oil, while the groups oligiotrichea and spirotrichaea have the ability to dominate a protozoan community exposed to crude oil concentrations of 10ppm and potentially influence the planktonic food chain. Effects of Salinity on the Toxicity of Oil Dispersants in Eastern Mud Snails B. Evans*1, P. Key2, K. Chung2, M. DeLorenzo2, M. Fulton2 1Eckerd College, St. Petersburg, FL, 2National Oceanic and Atmospheric Administration, National Ocean Service, Center for Coastal Environmental Health and Biomolecular Research, Charleston, SC Chemical dispersants can be an effective method for combating oil spill disasters. However, their use in mitigation should be carefully considered due to their potential toxic effects in the marine environment. While dispersant toxicity may be established under standard conditions, it is uncertain what role abiotic factors might have on their toxicity. This study looked at the effect of salinity on oil dispersant toxicity in the Eastern mud snail, Ilyanassa obsoleta, a common estuarine species. Using two dispersants authorized for oil spill response, Corexit 9500 and Finasol OSR 52, mean acute lethal toxicity (LC50) values and sublethal effects were examined at 10, 20, and 30 ppt salinity in adult and larval snails. Two biomarkers (lipid peroxidation and acetylcholinesterase) were used to measure sublethal effects. The 96-hour static renewal LC50 values indicated significant differences in toxicity between dispersants and salinities. Larval snails were significantly more sensitive than adult snails to both dispersants, and both life stages were significantly more sensitive to Finasol than to Corexit. Larval snails were more sensitive to dispersants at lower salinity, while adult snails were more sensitive at higher salinities. Dispersants increased lipid peroxidation activity and decreased acetylcholinesterase activity in adults. These results demonstrate that dispersant toxicity varies among compounds and organism life stages, and that physicochemical properties of the environment, such as salinity, affect the potential dispersant toxicity to estuarine species. 3 *Student presenter Efficacy and Ecotoxicological Effects of Shoreline Cleaners in Salt Marsh Ecosystems M. DeLorenzo, P. Key, E. Wirth, P. Pennington, K. Chung, E. Pisarski, B. Shaddrix, M. Fulton NOAA, National Centers for Coastal Ocean Science, Charleston, SC Oil spills that occur in estuaries, bays, or enclosed harbors have the potential to contaminate docks, bulkheads, ship hulls, and sensitive estuarine habitat. Depending on the situation and location, shoreline cleaners may be applied to oiled surfaces within inshore areas. Decisions as to where and when individual products will be utilized depend on understanding the efficacy, environmental fate, and environmental effects of these compounds. This study evaluated the efficacy and possible ecotoxicity of three shoreline cleaner products (Accell Clean, PES-51, and Cytosol) using a salt marsh mesocosm test system and laboratory exposures. Ceramic tiles were used to represent oiled seawall. The mesocosms were dosed with oil, followed by shoreline cleaner application to the oiled tiles. Samples were collected at multiple time-points during the 30-day experiment. The Oil+Accell treatment significantly reduced fish, mud snail, and clam survival compared to the control. Both the Oil+Accell and Oil+Cytosol treatments significantly reduced amphipod and polychaete survival. Sublethal effects were observed on clam and marsh grass growth, and dissolved oxygen content was reduced in the shoreline cleaner treatments. While the Oil+Accell treatment had the greatest animal mortality, it had the highest bacterial (heterotrophic and Vibrio) densities. Bacterial densities returned to pre-dose levels after 30d. The Oil+Accell treatment had significantly higher measured hydrocarbons (TEH and Total PAH50) in the water column 24h post-cleaner application than the oil alone treatment, the Oil+PES treatment and the control. The results of this study will help inform management decisions regarding the use of shoreline cleaners in oil-spill response, particularly with regard to estuarine species. Efficient Dispersion of Crude Oil by Blends of Food-Grade Surfactants: Toward Greener Oil Spill Treatments D. Riehm1, J. Athas2, J. Neilsen3, G. Bothun3, V. John4, S. Raghavan2, A. McCormick1 1University of Minnesota, Minneapolis, MN, 2University of Maryland, College Park, MD, 3University of Rhode Island, Kingston, RI, 4Tulane University, New Orleans, LA Recent work has suggested that marine oil dispersants containing blends of the nontoxic surfactants lecithin (L) and Tween 80 (T) may be effective alternatives to traditional dispersant