Oil Spill Dispersant Effectiveness Protocol. I: Impact of Operational Variables |
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Authors: | George A Sorial Albert D Venosa Karen M Koran Edith Holder Dennis W King |
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Affiliation: | 1Associate Professor, Dept. of Civil and Environmental Engineering, Univ. of Cincinnati, Cincinnati, OH. 45221-0071 (corresponding author). E-mail: george.sorial@uc.edu 2Senior Research Microbiologist, National Risk Management Research Laboratory, U.S. Environmental Protection Agency, 26 W. Martin Luther King Dr., Cincinnati OH 45268. 3Research Associate, Dept. of Civil Environmental Engineering, Univ. of Cincinnati, Cincinnati, OH 45221-0071. 4Research Associate, Dept. of Civil and Environmental Engineering, Univ. of Cincinnati, Cincinnati, OH 45221-0071. 5President and Senior Statistician, Statking Consulting, Inc., Fairfield, OH 45014.
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Abstract: | The current U.S. Environmental Protection Agency protocol for testing the effectiveness of dispersants, the swirling flask test, has been found to give widely varying results in the hands of different testing laboratories. The sources of the ambiguities in the test were determined by considering several options in a rigorous systematic fashion. Options considered were variability among three operators and the variability and limitations of three analytical instruments in establishing a calibration curve for oil/dispersant mixtures. Other options included flask type, impact of operational variables (rotational speed, mixing time, settling time, and oil:dispersant ratio), development of a revised procedure for dispersant effectiveness, reproducibility and repeatability of the revised procedure, and development of selection criteria for screening of dispersants. A redesign of the test flask, which is characterized by having baffles with a stopcock at the bottom for sample collection, was deemed necessary to accomplish reproducibility within operator and between operators. The results indicated that the baffled flask provided a total coefficient of variation (variations within operator and between operators) less than 11% compared to above 100% in some cases for the swirling flask. |
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Keywords: | Oil spills Crude oil Dispersion Screening Sea water Protocols |
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