Research on Dispersants that Informs Oil Spill Response

– April 27, 2015

(Click to enlarge) The crew of a Basler BT-67 fixed wing aircraft release oil dispersant over an oil spill from the mobile offshore drilling unit, Deepwater Horizon, off the shore of Louisiana, May 5, 2010. (U.S. Coast Guard photo by Petty Officer 3rd Class Stephen Lehmann)

The second in a three-part series of GoMRI science-for-response articles

The prevention or reduction of coastline oiling was high on responders’ priorities immediately following the 2010 Deepwater Horizon oil spill. Five years later, much discussion continues about balancing benefits and risks regarding dispersants, and there are increased research efforts for alternatives or enhancements to existing dispersant systems.

Recently, consortia directors and leads for smaller-group projects funded by the Gulf of Mexico Research Initiative (GoMRI) talked about how their science could be used to inform an oil spill response. This article focuses on the science advances and tools related to dispersant use in the case of future spills. It is the second in a three-part GoMRI science-for-response article series. The first was Research on Oil Transport that Informs Spill Response and the third will be Research on Oil Biodegradation and Monitoring that Informs Spill Response.

A GROWING BODY OF RESEARCH HIGHLIGHTS THE RANGE OF RISKS VERSUS BENEFITS associated with dispersant use. DROPPS director Edward Buskey summed up an often-repeated reply when members of the GoMRI science community are asked about dispersants use as research unfolds regarding potential subsequent impacts:

If it were clear, based on combined modeling predictions that an oil slick would head to sensitive coastlines like the marshes and sea grass beds, then probably the use of dispersants at the surface would be justified. If not, it might be better to leave the oil at sea and recover it at the surface. Dispersant-related research should prompt rigorous discussion about its use, especially in the deep sea.

The first-time use of dispersants in a sub-sea application is of particular interest as it was believed to play a role in the development and lingering of deep-water oil plumes that subsequently transported oil across the Gulf. C-IMAGE director Steven Murawski explained:

Understanding whether or not dispersants used at the well head were effective in reducing the quantity of oil that reached the surface can inform decisions about the efficacy of sub-surface dispersant use if there were a similar deep-sea blowout.

C-IMAGE experiments in high-pressure facilities that recreate the conditions at the Macondo wellhead site are providing new insights about natural processes associated with extreme depths and low temperatures. Their resultant model simulations of plume formation suggest that subsea dispersant application may not have been necessary to reduce surface slicks.

Deep-C field studies about coastal beaches followed by laboratory analyses show that dispersant may cause oil to go deeper into sediment and sand. Several consortia conducted a time-series study on deep-sea sediment that indicate a large organic carbon influx, likely from oil-contaminated marine snow, altered sediment conditions and may have contributed to density decreases in sediment-dwelling microorganisms. ECOGIG research about deep-water marine communities has located impacted cold water corals linked to an uneven spread of pollutants via chemically-dispersed oil droplets.

Scientists with DROPPS have conducted studies about dispersant effects on the physical and biological ocean processes that regulate oil fate. They have found that plankton ingest the smaller dispersed oil droplets, providing a pathway for contaminants to enter the marine food web base, and that dispersants enhanced hydrocarbon toxicity in zooplankton and microzoolankton and inhibited plankton growth.

C-MEDS laboratory studies about bubble bursting phenomenon suggest that dispersants can facilitate oil droplet transport in a downward spray into the water and an upward aerosolization into the atmosphere. Research from Elizabeth Kujawinski and Helen White show that dispersant components still linger in Gulf waters.

The safety of dispersant components is the focus of two research teams. Darrell Sparks’s group is looking at DNA-level impacts on fish larvae, and Demetri Spyropoulos’ group is looking at cellular-level impacts on public health. Their studies to determine impacts from high-dose acute and low-dose chronic exposure to dispersant components could provide insights about risks and inform alternative formulations. Spyropoulos explained that their research suggests a need for further testing of dispersant formulations with regard to human and ecosystem health:

We are finding that DOSS, a principal component in dispersants and in many personal care products, is likely to be an obesogen that drives fat cell production and changes metabolism. This and other studies are setting the stage for ‘stem cell behavior’ testing to help determine levels of concern related to exposures and the obesity epidemic.

RESEARCH IS SHOWING PROMISE FOR MODIFICATIONS TO OR SUBSTITUTES FOR DISPERSANTS SYSTEMS. C-MEDS director Vijay John offered several science-based suggestions to inform decision makers’ discussions about future dispersant use in the event of future oil spills:

If federal agencies decide they have to use dispersants, we could suggest component substitutes or synergistic dispersants. If the decision is to skim, burn, or use other ways to physically collect oil, then we have systems that herd oil effectively. If the decision is to not use dispersants, we are working on systems that deliver nutrients to organisms and speed up biodegradation.

Scott Grayson and his group are finding that increasing the molecular-level connectivity of dispersants may help effectiveness since dispersants can become highly diluted in a large open-ocean application. Stronger bonds could potentially reduce the overall amount needed for oil spill response.

John explained that there may be circumstances where dispersants cannot be used, which increases the value in having multiple response options:

If a spill is in the artic between ice, the sea is likely too calm for dispersants to be effective and logistics could be difficult. A deep-sea spill may not be discovered until a lot of oil surfaces and sub-sea injection may not be an option. Our development of non-biodegradable and plant-based biodegradable components extends time for recovery and provides options that can assist with removing or burning the oil.

RESEARCHERS HAVE ENGAGED RESPONDERS AND INDUSTRY REPRESENTATIVES to improve information sharing and collaboration with regard to dispersant research. Several GoMRI consortia have been interacting with the American Petroleum Institute (API), an industry trade organization involved with developing response strategies and hosting oil spill task force meetings. John provided information about C-MEDS interactions:

Representatives from industry are on our advisory board to help bridge communications about dispersant research between academia and responders. They engage us in vibrant discussions about what is important from a different point of view.

John’s colleague Alon McCormick explained that their research about how dispersants work at the individual compound level combined with their industry relationships provides possibilities for generating viable dispersant options:

Our research can offer meaningful information that could guide decisions about currently-available dispersants and about compound changes that could make them more environmentally benign. Industry (through API) has been the primary movers behind developing and testing dispersants with different oils at larger scales, generating the kind of results that inform federal agency decisions.

The capability of industrial testing in tanks and facilities opens up the possibility for change, and John said that that is happening:

API has asked Srinivasa Raghavan to supply our newly-developed lecithin formulations for initial tests. There are no guarantees about the outcome, but we have to try. It’s the first step to transferring our fundamental work to potential response products.

John explained that right now, there is no dispersant alternative that is accepted, staged, and ready for use in an oil spill response, particularly on a large scale. However, people connected to oil spill response indicate that there is interest in knowing what would happen if less dispersants were used, applied in different ways, modified, or optimized.

GoMRI-FUNDED SCIENTISTS HAVE BEEN CONDUCTING RESEARCH to improve society’s ability to understand, respond to, and mitigate the impacts of petroleum pollution and related stressors on marine and coastal ecosystems. Communication and collaboration are critical for getting science to the right people at the right time during a response. Researchers are seeing positive signs of progress in improving their working relationships with the response community.

To learn more about GoMRI research mentioned above, refer to the following information:

C-IMAGE: the Center for Integrated Modeling and Analysis of Gulf Ecosystems consortium, Director Steven Murawski, University of South Florida College of Marine Science. C-IMAGE publications and website

C-MEDS: the Consortium for the Molecular Engineering of Dispersant Systems, Director Vijay T. John, Tulane University Department of Chemical and Biomolecular Engineering. C-MEDS publications and website

Deep-C: the Deepsea to Coast Connectivity in the Eastern Gulf of Mexico consortium, Director Eric P. Chassignet, Florida State University Center for Ocean-Atmospheric Prediction Studies. Deep-C publications and website

DROPPS: the Dispersion Research on Oil: Physics and Plankton Studies, Director Edward J. Buskey, The University of Texas at Austin Department of Marine Science. DROPPS publications and website

ECOGIG: the Ecosystem Impacts of Oil and Gas Inputs to the Gulf consortium, Director Charles Geoffrey Wheat, University of Mississippi, ECOGIG publications and website 

RFP-II: Investigator Grants:

• Characterizing the Composition and Biogeochemical Behavior of Dispersants and Their Transformation Products in Gulf of Mexico Coastal Ecosystems,
• Development of Cost-Efficient and Concentration-Independent Dispersants for Improved Oil Spill Remediation,
• Using Embryonic Stem Cell Fate to Determine Potential Adverse Effects of Petroleum/Dispersant Exposure, and
• Weathering of Petroleum and Dispersant Components in the Aftermath of the Deepwater Horizon Oil Spill

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This research was made possible by grants from BP/The Gulf of Mexico Research Initiative (GoMRI). The GoMRI is a 10-year independent research program established to study the effect, and the potential associated impact, of hydrocarbon releases on the environment and public health, as well as to develop improved spill mitigation, oil detection, characterization and remediation technologies. An independent and academic 20-member Research Board makes the funding and research direction decisions to ensure the intellectual quality, effectiveness and academic independence of the GoMRI research. All research data, findings and publications will be made publicly available. The program was established through a $500 million financial commitment from BP. For more information, visit https://gulfresearchinitiative.org/.

© Copyright 2010- 2017 Gulf of Mexico Research Initiative (GoMRI) – All Rights Reserved. Redistribution is encouraged with acknowledgement to the Gulf of Mexico Research Initiative (GoMRI). Please credit images and/or videos as done in each article. Questions? Contact web-content editor Nilde “Maggie” Dannreuther, Northern Gulf Institute, Mississippi State University (maggied@ngi.msstate.edu).