A New Laboratory Method for Evaluating Oil Spill Dispersants

Recent inland spills in Latin America have generated interest in dispersant use for freshwater oil spills. However, oil spill dispersants primarily are formulated for use in marine waters. Dispersants that are designed for saltwater use show reduced effectiveness when applied in freshwater. The effectiveness of COREXIT® 9500 in low salinity waters varies with the type of oil, the dispersant-to-oil ratio (DOR), and other factors. The effectiveness of COREXIT® 9500 can decrease markedly at salinities of 15 ppt or less. The authors observed an increase in effectiveness of COREXIT® 9500 in freshwater when the dispersant was blended with an inorganic, divalent salt, such as calcium chloride, prior to use (patent pending). COREXIT® 9500* refers here to the blend of the salt and dispersant. The Exxon Dispersant Effectiveness Test (EXDET) was used to evaluate dispersant performance in deionized water and in river water samples from Rio de la Plata, Argentina. COREXIT® 9500 showed 22% effectiveness on Alaska North Slope (ANS) crude oil in deionized water, a value indicative of poor effectiveness. Depending on the amount of calcium chloride added, COREXIT® 9500* showed up to 63% effectiveness on ANS crude oil in deionized water, which indicates good effectiveness. The effectiveness of COREXIT® 9500* and COREXIT® 9500 was compared for three additional crude oils both in deionized water and in river water. In all cases, the effectiveness of COREXIT® 9500 was lower compared with COREXIT® 9500*.

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“…1 Each value is an average percent effectiveness measured in an EXDET. 2 COREXIT® 9500 with calcium chloride solution added.…”

Section: Discussionmentioning

confidence: 99%

“…The Exxon Dispersant Effectiveness Test (EXDET) was used to evaluate dispersant performance. Becker et al (1991Becker et al ( . 1993 contains a detailed description of the EXDET method.…”

Section: Methodsmentioning

confidence: 99%

Modification of the Dispersant Corexit®9500 for Use in Freshwater

George-Ares

Lessard

Canevari³

et al. 2001

International Oil Spill Conference Proceedings

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“…Several laboratory protocols have been developed for testing the relative efficacy of different dispersants: the air current test (Mackay et al 1978 ), the Warren Springs rolling flask test (Martinelli 1984 ), the swirling flask test (Clayton et al 1993 ), the Exxon dispersant effectiveness test (Becker et al 1993 ), and the baffled flask test (Venosa et al 2002 ) among others. Comparisons of these tests with field and tank data have been reported by Clark et al ( 2005 ), and the baffled flask test was used to compare eight potential dispersants during the response to the Deepwater Horizon spill (Venosa and Holder 2012 ).…”

Section: Introductionmentioning

confidence: 99%

A protocol for assessing the effectiveness of oil spill dispersants in stimulating the biodegradation of oil

Prince

Butler

2013

Environ Sci Pollut Res

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Dispersants are important tools in oil spill response. Taking advantage of the energy in even small waves, they disperse floating oil slicks into tiny droplets (<70 μm) that entrain in the water column and drift apart so that they do not re-agglomerate to re-form a floating slick. The dramatically increased surface area allows microbial access to much more of the oil, and diffusion and dilution lead to oil concentrations where natural background levels of biologically available oxygen, nitrogen, and phosphorus are sufficient for microbial growth and oil consumption. Dispersants are only used on substantial spills in relatively deep water (usually >10 m), conditions that are impossible to replicate in the laboratory. To date, laboratory experiments aimed at following the biodegradation of dispersed oil usually show only minimal stimulation of the rate of biodegradation, but principally because the oil in these experiments disperses fairly effectively without dispersant. What is needed is a test protocol that allows comparison between an untreated slick that remains on the water surface during the entire biodegradation study and dispersant-treated oil that remains in the water column as small dispersed oil droplets. We show here that when this is accomplished, the rate of biodegradation is dramatically stimulated by an effective dispersant, Corexit 9500®. Further development of this approach might result in a useful tool for comparing the full benefits of different dispersants.

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“…Over the dozens of years, many laboratory tests have been developed for assessing the effectiveness of the chemical dispersant, which have the advantages of simply, low cost and well controlled. Such as the SFT [10] and BFT [11][12][13] used by USEPA, EXDET test [14], WSL test [15], MNS test [16] and IFP test [17]. Many researchers have used one or more test methods to measure the effectiveness of dispersants.…”

Section: Effectiveness Test Methods Of Chemical Dispersantmentioning

confidence: 99%

A Review of Research and Practice on the Application of Chemical Dispersant in Oil Spills

Qian

2014

AMR

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Chemical dispersant has been widely used in oil spill response around the world as an effective method. The study reviews the mechanism of chemical dispersion, the factors influenced dispersant effectiveness, the test methods of dispersant effectiveness, and applications in oil spills around the world. Then some questions on the research for chemical dispersants used during oil spills in China were discussed.

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A New Laboratory Method for Evaluating Oil Spill Dispersants

Cited by 6 publications

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Modification of the Dispersant Corexit®9500 for Use in Freshwater

Modification of the Dispersant Corexit®9500 for Use in Freshwater

A protocol for assessing the effectiveness of oil spill dispersants in stimulating the biodegradation of oil

A Review of Research and Practice on the Application of Chemical Dispersant in Oil Spills

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