THE GRANT and GOMRI : WHERE DID THE OIL GO? PARTNERSHIP Monica Wilson, Larissa Graham, Christine Hale, Emily Maung-Douglass, Stephen The mission of Sea Grant is Sempier, Tara Skelton, and LaDon Swann to enhance the practical use and conservation of coastal, marine, and Great During the Deepwater Horizon (DWH) , approximately 200 million resources in order to create a sustainable economy and gallons of oil flowed from the Macondo well. Of the 200 million gallons, environment. There are 33 responders recovered 17 percent directly from the , releasing university–based Sea Grant programs throughout the 172 million gallons of oil into the of . Due to the size and scope coastal U.S. These programs of the spill, people wanted to know where the oil would travel. Some oil are primarily supported by the National Oceanic and accumulated at the shoreline, on the ’s surface, and in an underwater Atmospheric Administration plume. Unexpectedly, a portion of the oil also found its way to the seafloor. and the states in which the programs are located. In the immediate aftermath of the Deepwater Horizon spill, BP committed $500 million over a 10–year period to create the Research Initiative, or GoMRI. It is an independent research program that studies the effect of releases on the environment and public health, as well as develops improved spill mitigation, oil detection, characterization, and remediation technologies. GoMRI is led by an independent and academic 20–member research board. The Sea Grant oil spill science outreach team identifies the best available science from projects funded by GoMRI and others, and only shares peer- reviewed research results.

Oil from Deepwater Horizon washes ashore. (NOAA, Dari Knight)

Texas • • Gulf residents wanted to know the oil’s path the tool established seven categories to - and its potential impacts on the marine describe the fate of the spilled oil (Figure gulfseagrant.org environment. In 2010, a group of scientists 1).1 For example, responders burned or developed an oil budget calculator to skimmed some surface oil immediately, estimate what happened to the oil and to but other oil lingered in the environment. provide a status update to the Incident The Sea Grant publication Top 5 Frequently gulfresearchinitiative.org Command. Scientists who developed Asked Questions about the Deepwater FIGURE 1. Scientists have estimated BIODEGRADATION approximately 11 to 25 percent of Oil seeps occur naturally in the marine the 200 million gallons of oil from environment, so in the 1 Deepwater Horizon is unaccounted for. ocean have evolved to be able to consume, Recent studies show that three to five percent of the total oil made its way or eat, oil. In the Gulf of Mexico hundreds onto the seafloor.20 (Florida Sea Grant/ of species of microbes such as , Anna Hinkeldey) archaea, and fungi degrade oil. This is known as biodegradation. Microbes play a key role in the biodegradation of oil in the ocean and can reduce the overall environmental impact.6,7

Horizon Oil Spill details the following categories: disperse, dissolve, or be broken down by microbes • recovered at the wellhead, (called biodegradation) or the sun.4,5 The study also did • skimmed, not calculate the amount of oil recovered by the Vessels- • burned, of-Opportunity program and the amount that sank to • chemically dispersed, the bottom.3 • naturally dispersed, • evaporated or dissolved, or OIL AT THE ’S SURFACE • unaccounted for.2 Because oil is less dense than water, most spilled oil floats A few points not covered in the original study include on the water’s surface. Currents, , discharge, the amount of weathering of surface oil.3 Over time, waves, and can move this surface oil, affecting where oil weathers as it interacts with the surrounding it up.8 Scientists use computer models to track the environment. It can evaporate, emulsify, naturally movement of oil at the water’s surface and predict its path.

2 TABLE 1. Number of of shoreline oiled by state.14 OIL ON THE SHORELINE State Miles of Percent of total During the DWH oil spill, a portion of the surface oil oiled shoreline oiled shoreline moved under the influence of the wind and ocean 35 3% currents to make its way to the . Texas, Mississippi, Louisiana 847 64% Alabama, and Florida all experienced shoreline Mississippi 158 12% oiling to different degrees (Figure 3). The oil impacted Alabama 95 7% approximately 1,313 miles (37 percent) of the 3,540 miles Florida 178 14% of Gulf of Mexico coastline. Total 1,313 100% Table 1 lists the amount of shoreline oiled by state. Louisiana received 64 percent of the oil that made it to synthetic Scientists also used imagery called shore. The two shoreline habitats primarily affected were aperture radar (SAR) to calculate the area affected beaches (46 percent) and coastal (52 percent). during the 87 days oil flowed freely into the Gulf. Results The remaining two percent included all other shoreline indicated surface oil reached a cumulative area of 57,000 types.14 square miles (Figure 2).9 Scientists found that winds and large river outflow from the kept OIL BELOW THE SURFACE WATER a portion of surface oil offshore.10 More oil could have Approximately one month after the spill began, scientists traveled offshore in the but was trapped aboard the R/V first found evidence of an oil in a large eddy on the northern part of the Loop Current. plume just under the water’s surface, called a subsurface The eddy remained stationary for several months, plume. Certain chemical compounds in oil emit a light that keeping the oil from reaching South Florida.11,12 allow them to be detected by fluorescence techniques. Evaporation Using colored dissolved organic matter (CDOM) Oil weathers over time as it interacts with the fluorometers, scientists discovered the subsurface oil surrounding environment. The amount of weathering, plume. They found elevated levels of CDOM at water the type of oil spilled, and the conditions during and depths greater than 3,280 feet and as far as eight miles after a spill influence how oil will move. Evaporation is from the wellhead. They took water samples from an important part of the weathering process for most areas with elevated levels of CDOM and found elevated oil spills.4,5,13 Typical crude oils can lose up to 45 percent levels of polycyclic aromatic (PAHs). of their initial volume due to evaporation in the first few The PAH concentrations confirmed that the elevated days following a spill.13 A significant fraction of the leaked levels of organic matter (CDOM) were related to oil DWH surface oil evaporated.4,5 contamination.15

FIGURE 2. During the Deepwater Horizon oil spill, the extent and amount of oiling on the sea surface varied across the Gulf of Mexico. Colors indicate the average volume of oil in each cell area, with the highest con- centrations (red) occurring near the wellhead.9 (Reprinted from MacDonald et al., 2010)

3 FIGURE 3. Varying amounts of oil reached the shorelines and impacted beaches (top) and coastal wetlands (bottom). (Reprinted from Nixon et al., 2016)

Using similar techniques other scientists analyzed over Other samples containing elevated fluorescence and low 5,000 water samples to track the deep water plume. In dissolved oxygen signals indicated the presence of oil as far addition to looking for oil droplets, they searched for other as 256 miles from the wellhead (Figure 4).16 evidence of contamination at the plume depth, including Other scientists confirmed the subsurface plume using the elevated PAHs, dissolved gas, fluorescence, and lowered autonomous underwater vehicle (AUV) Sentry (Figure 5). dissolved oxygen levels. Water samples containing oil They collected and tested water samples and found the droplets were found as far as 96 miles from the wellhead. subsurface oil plume between depths of 3,380 and 4,265 feet in late May and early June of 2010. Although more OILED WASTE MATERIAL than 22 miles in length and existing for months after the Approximately 100 million pounds of oiled waste oil spill, the subsurface plume was not a river of oil floating materials were removed from sand beaches during under water.17 The plume was simply an area that had response activities.28 (adapted from Michel, 2015) elevated amounts of PAHs compared to other areas.18 The subsurface plume trapped approximately 35 percent of State Prior to June 2011 - June 2011 February 2014 the spilled oil, but scientists are uncertain of the plume’s (pounds) (pounds) ultimate fate.18,19

Texas 17,454 0 OIL ON THE SEAFLOOR Louisiana 76,062,800 15,176,296 Estimating the total amount of oil that made its way to the Mississippi 3,886,415 113,061 seafloor is difficult. Deep sea currents move the deposited Alabama 2,569,200 930,656 oil, causing it to accumulate in dips and depressions on Florida Not available 66,276 the seafloor. Marine animals that live on the bottom bury

4 a.

FIGURE 4. Scientists took offshore water samples to track the deep plume, mapping surface oil spreading out from the wellhead in red and the deep plume going towards the southwest in yellow/green (a). In a three- dimensional underwater model (b), a column of oiled samples rises from the wellhead to the surface while the deep plume extended 256 miles southwest from the wellhead. Colors relate to the phases of each sample’s oil—samples with b. Deepwater Horizon oil droplets (red); dissolved oil without oil droplets (blue); or containing poorly defined oil fingerprints but with other evidence of oil such as dissolved oxygen or fluorescence (yellow/green).16 (Adapted from Payne and Driskell, 2015) it, move it, and change its distribution. Scientists used had been polluted with different amounts of oil and oil- different chemical techniques to understand how much derived carbon from the spill. While oil on the seafloor had oil made it to the seafloor. They estimated that an area of not been included in the original oil budget, recent studies approximately 1,235 square miles around the Macondo well show that about three to five percent of the oil discharged from the well made its way to the seafloor.20-22 Sedimentation of oil Although oil normally floats on the surface, it can make its way to the bottom when it attaches to other, heavier particles in the water. Sedimentation occurs when the oil and particles land on the seafloor.23 This may occur near a river or in shallow areas. flowing into the Gulf can introduce and other sticky materials that attach to the oil. For example, large volumes of water from the Mississippi River contain small particles that could have combined with the oil.24 Certain biological processes may also form sticky particles, called , that can

FIGURE 5. The autonomous underwater vehicle (AUV) Sentry confirmed the deep subsurface oil plume between depths of 3,380 and 4,265 feet. The plume was more than 22 miles in length.17 (Woods Hole Oceanographic Institution/ Will Koeppen)

5 capture the oil droplets and cause them to sink. Marine Scientists believe that MOFFSA-related activities caused snow may contain tiny , microbes, mucous web- some of the oil to accumulate on the seafloor.24 like threads, pieces of small decaying animals, feces, and Researchers continue to work to better understand other bodily waste that may carry contaminants from the where the oil went, how long it might stay there, and its 25 surface to the bottom (Figure 6). impacts on the marine environment. The Gulf of Mexico During the DWH spill scientists learned that marine snow Research Initiative (GoMRI) funds these ongoing studies. trapped the oil, carrying it downward to the seafloor Emerging information can be found on GoMRI’s website where it accumulated.26 The oil along with ash from on- at http://gulfresearchinitiative.org. To access other site burning became part of marine snow. The sinking of oil spill-related publications or view the references marine snow contributed to the sedimentation of oil from in this publication on Sea Grant Oil Spill Science the spill. This event has been termed Marine Oil Snow Outreach Program website: www.gulfseagrant.org/ Sedimentation and Flocculent Accumulation (MOSSFA).27 oilspilloutreach.

FIGURE 6. Oil can take many paths to reach the ocean floor. (Florida Sea Grant/Anna Hinkeldey, adapted from Deepwater Horizon Natural Resource Damage Assessment Trustees)

6 GLOSSARY REFERENCES

Autonomous underwater vehicle (AUV) — Programmable 1. Lehr, W., Bristol, S., & Possolo, A. (2010). Oil budget robotic vehicles that can drift, drive, or glide through the calculator Deepwater Horizon. Retrieved from Federal Interagency Solutions Group, Oil budget calculater science ocean without being controlled by humans. and team. https://www.restorethegulf.gov/ sites/default/files/documents/pdf/OilBudgetCalc_Full_ Colored dissolved organic matter (CDOM) — Dissolved HQ-Print_111110.pdf organic matter in the water that consists of broken down 2. Maung-Douglass, E., WIlson, M., Graham, L., Hale, C., plant parts, such as leaves, algae, or phytoplankton. Sempier, S., and Swann, L. (2015). Oil Spill Science: Top 5 frequently asked questions about Deepwater Horizon oil spill. Eddy — A current having a rotary or circular motion. GOMSG-G-15-002. 3. Fingas, M. (2013). MACONDO well mass balance: Emulsify — Occurs when water and oil combine, with one A chemical view. Proceedings of and Marine Oil Spill being suspended in the other. For crude oils, it refers to the Program Technical Seminar, 75-102. process where sea water droplets become suspended in 4. Ryerson, T. B., Aikin, K. C., Angevine, W. M., Atlas, E. L., Blake, D. R., Brock, C. A., . . . Watts, L. A. (2011). the oil by mixing due to turbulence. Atmospheric emissions from the Deepwater Horizon spill constrain air-water partitioning, hydrocarbon fate, Fluorescence — A substance absorbing light that re-emits and leak rate. Geophysical Research Letters, 38(7), the light as a different color. doi:10.1029/2011GL046726 5. Liu, Z., Liu, J., Zhu, Q., & Wu, W. (2012). The weathering of Fluorometer — An instrument used to measure re- oil after the Deepwater Horizon oil spill: insights from the emission of light by a substance. chemical composition of the oil from the sea surface, salt marshes and . Environmental Research Letters, Loop Current — A warm that flows 7(3), 035302. northward between and the Yucatan Peninsula, 6. Atlas, R. M., & Hazen, T. C. (2011). Oil biodegradation and moves north into the Gulf of Mexico, loops east and south biorememdiation: A tale of the two worst spills in U. S. History. Environmental Science & Technology, 46(16), 8799- before exiting to the east through the Florida Straits and 8807. doi.10.1021/es2013227 joining the Gulf to flow between Florida and the 7. Head, I. M., Jones, D. M., & Roling, W. F. M. (2006). Marine Bahamas. microorganisms make a meal of oil. Nature Reviews Microbiology, 4(3), 173-182. doi:10.1038/nrmicro1348 Marine snow — A shower of biological material falling from 8. Dietrich, J. C., Trahan, C. J., Howard, M. T., Fleming, J. G., the surface to the deep ocean. Weaver, R. J., Tanaka, S., . . . Twilley, R. R. (2012). Surface trajectories of oil along the Northern Coastline of Oil-derived carbon — Oil-derived chemicals from the Gulf of Mexico. Research, 41, 17-47. http://dx.doi.org/10.1016/j.csr.2012.03.015 weathering, microbial degradation, and ingestion of oil by 9. MacDonald, I. R., Garcia-Pineda, O., Beet, A., Daneshgar Asl, marine organisms. S., Feng, L., Graettinger, G., . . . Swayze, G. (2015). Natural and unnatural oil slicks in the Gulf of Mexico. Journal of Oil seeps — Areas where oil and flow up Geophysical Research: , 120(12), 8364-8380. naturally through cracks in the at a slow rate. doi:10.1002/2015JC011062 10. Kourafalou, V. H., & Androulidakis, Y. S. (2013). Influence Polycyclic aromatic hydrocarbons (PAHs) — One of the of Mississippi River induced circulation on the Deepwater many chemical groups found in oil, tar, smoke from burning Horizon oil spill transport. Journal of Geophysical Research: oil, coal, wood, or decaying vegetation; used to identify oil Oceans, 118(8), 3823-3842. doi:10.1002/jgrc.20272 11. Le Hénaff, M., Kourafalou, V. H., Paris, C. B., Helgers, J., Aman, in the environment. Z. M., Hogan, P. J., & Srinivasan, A. (2012). Surface evolution of the Deepwater Horizon oil spill patch: combined effects of Sedimentation — Occurs when particles (or sediment) circulation and wind-induced drift. Environmental Science & suspended in a liquid settle and get deposited on the Technology, 46(13), 7267-7273. doi:10.1021/es301570w bottom. 12. Walker, N. D., Pilley, C. T., Raghunathan, V. V., D’Sa, E. J., Leben, R. R., Hoffmann, N. G., . . . Turner, R. E. (2011). Impacts Synthetic aperture radar (SAR) — Satellite- or aircraft- of Loop Current frontal cyclonic eddies and wind forcing borne radar system used to create images of ground on the 2010 Gulf of Mexico oil spill. In Monitoring and Modeling the Deepwater Horizon Oil Spill: A Record-Breaking features, terrain, and oceans. Enterprise (pp. 103-116): American Geophysical Union. doi:10.1029/2011GM001120 (-ed, -ing, -s) — A collection of physical, chemical, 13. Fingas, M. (2011). Chapter 9 - Evaporation modeling. In M. and microbial processes that alter and break down oil. It Fingas (Ed.), Oil Spill Science and Technology (pp. 201-242). includes processes such as oil spreading, evaporation, Boston: Gulf Professional Publishing. dispersing, biodegradation, and photooxidation. These 14. Nixon, Z., Zengel, S., Baker, M., Steinhoff, M., Fricano, G., Rouhani, S., & Michel, J. (2016). Shoreline oiling from the processes are influenced by many factors (e.g., type of oil Deepwater Horizon oil spill. Marine Bulletin, 107(1), being weathered, temperature, bacteria present). 170-178. http://dx.doi.org/10.1016/j.marpolbul.2016.04.003 15. Diercks, A.-R., Highsmith, R. C., Asper, V. L., Joung, D., Zhou, 29. Michel, J, Fegley, S, & Dahlin, J. (2015). Deepwater Horizon Z., Guo, L., . . . Lohrenz, S. E. (2010). Characterization of sand beach injury assessment. Seattle, WA. U.S. Dept. of subsurface polycyclic aromatic hydrocarbons at the Deepwater Interior, Deepwater Horizon Response & Restoration, Admin. Horizon site. Geophysical Research Letters, 37(30), L20602. Record. DWH Shoreline NRDA Technical Working Group Report. doi:10.1029/2010GL045046 Retrieved from https://www.fws.gov/doiddata/dwh-ar-docu- ments/894/DWH-AR0104418.pdf 16. Payne, J. R., & Driskell, W. (2015). 2010 DWH offshore samples - Forensic assessments and oil exposures. Seattle, WA. U.S. Dept. of Interior, Deepwater Horizon response SUGGESTED CITATION: & Restoration, Admin. Record, DWH Natural Resource Dam- age Assessment Chemistry Technical Working Group Report. Wilson, M., Graham, L., Hale, C., Maung-Douglass, E., Retrieved from https://www.fws.gov/doiddata/dwh-ar-docu- Sempier, S., Skelton, T., and Swann, L. (2017). Oil spill ments/946/DWH-AR0039118.pdf science: Deepwater Horizon—Where did the oil go. 17. Camilli, R., Reddy, C. M., Yoerger, D. R., Van Mooy, B. A. S., Jakuba, M. V., Kinsey, J. C., . . Maloney, J. V. (2010). Tracking hydrocarbon GOMSG-G-17-006. plume transport and biodegradation at Deepwater Horizon. Science, 330(6001), 201-204. doi:10.1126/science.1195223 18. Reddy, C. M., Arey, J. S., Seewald, J. S., Sylva, S. P., Lemkau, K. OIL SPILL SCIENCE OUTREACH TEAM L., Nelson, R. K., . . . Camilli, R. (2012). Composition and fate of gas and oil released to the water column during the Deepwater Christine Hale Horizon oil spill. Proceedings of the National Academy of Sciences, 109(50), 20229-20234. doi:10.1073/pnas.1101242108 Texas Sea Grant College Program [email protected] 19. Ryerson, T. B., Camilli, R., Kessler, J. D., Kujawinski, E. B., Reddy, C. M., Valentine, D. L., . . . Warneke, C. (2012). Chemical data quantify Deepwater Horizon hydrocarbon flow rate and environmental Larissa Graham distribution. Proceedings of the National Academy of Sciences, Mississippi-Alabama Sea Grant Consortium 109(50), 20246-20253. doi:10.1073/pnas.1110564109 [email protected] 20. Chanton, J., Zhao, T., Rosenheim, B. E., Joye, S., Bosman, S., Brunner, C., . . . Hollander, D. (2015). Using natural abundance Emily Maung-Douglass radiocarbon to trace the flux of petrocarbon to the seafloor Louisiana Sea Grant College Program following the Deepwater Horizon oil spill. Environmental Science & Technology, 49(2), 847-854. doi:10.1021/es5046524 [email protected] 21. Stout, A. S., & Payne, J. R. (2016). Macondo oil in deep-sea Stephen Sempier sediments: Part 1 Sub-sea weathering of oil deposited on the seafloor. Bulletin, 111(1-2), 365-380. https://doi. Mississippi-Alabama Sea Grant Consortium org/10.1016/j.marpolbul.2016.07.036 [email protected] 22. Valentine, D. L., Fisher, G. B., Bagby, S. C., Nelson, R. K., Reddy, C. Tara Skelton M., Sylva, S. P., & Woo, M. A. (2014). Fallout plume of submerged oil from Deepwater Horizon. Proceedings of the National Mississippi-Alabama Sea Grant Consortium Academy of Sciences, 111(45), 15906-15911. doi:10.1073/ [email protected] pnas.1414873111

23. Muschenheim, D. K., & Lee, K. (2002). Removal of oil from the sea LaDon Swann surface through particulate interactions: Review and prospectus. Mississippi-Alabama Sea Grant Consortium Spill Science & Technology Bulletin, 8(1), 9-18. https://doi. [email protected] org/10.1016/S1353-2561(02)00129-9

24. Kinner, N. E., Belden, L., & Kinner, P. (2014). Unexpected sink Monica Wilson for Deepwater Horizon oil may influence future spill response. Florida Sea Grant, UF/IFAS Extension Eos, Transactions American Geophysical Union, 95(21), 176. doi:10.1002/2014EO210005 [email protected]

25. Alldredge, A. L., & Silver, M. W. (1988). Characteristics, dynamics and significance of marine snow. Progress in Oceanography, 20(1), 41-82. http://www.sciencedirect.com/science/article/ pii/0079661188900535

26. Passow, U., & Ziervogel, K. (2016). Marine snow sedimented oil released during the Deepwater Horizon spill. Oceanography, Texas • Louisiana • Florida 29(3), 118-125. https://doi.org/10.5670/oceanog.2016.76 Mississippi-Alabama 27. Daly, K. L., Passow, U., Chanton, J., & Hollander, D. (2016). Assessing the impacts of oil-associated marine snow formation and sedimentation during and after the Deepwater Horizon oil spill. Anthropocene, 13, 18-33. https://doi.org/10.1016/j. ancene.2016.01.006 This work was made possible in part by a grant from The Gulf of 28. Deepwater Horizon Natural Resource Damage Assessment Mexico Research Initiative, and in part by the Sea Grant programs Trustees. (2016). Chapter 4 - Injury to natural resouces. In of Texas, Louisiana, Florida and Mississippi-Alabama. The Deepwater Horizon oil spill: Final programmatic damage statements, findings, conclusions and recommendations do not assessment and restoration plan and final programmatic environmental impact statement. Retrieved from http://www. necessarily reflect the views of these organizations. gulfspillrestoration.noaa.gov/restoration-planning/gulf-plan GOMSG-G-17-006