The document provides an overview of the 2010 Deepwater Horizon oil spill, the largest spill in history. It details the impacts on the environment, economy, and public health. It also summarizes lessons learned from previous spills like Exxon Valdez, noting most indicators return to normal within 3-5 years. Recommendations include developing improved monitoring, cleanup technologies, and understanding impacts of subsea spills and dispersant use. The goal is supporting natural recovery while removing oil and keeping response efforts technical rather than political.

1. Oil Spill Overview and Recommendations for Moving ForwardDeepwater Horizon OilEdward B. Overton, Ph.D.Professor EmeritusDept of Environmental SciencesSchool of Coast and EnvironmentLouisiana State UniversityBaton Rouge LA 70803Exxon Valdez Oil

2. Deepwater Horizon Spill

3. Overview of the SpillBegan April 20, 2010 with the explosion of the Deepwater Horizon drilling platform in the Gulf of MexicoCapped on July 15, 2010Estimates of 35,000-60,000 barrels of crude oil flowed from the well per day, covering 2,500 square miles>5M barrels of oil spilled – Largest spill in history>1M barrels of dispersant used at depth and on the surfaceImpact to people, environment, economy, and geology

5. 7721 milesof coastline in Louisiana

6. On Shore Oil

8. Offshore Oil

10. Thick, skimable, dispersible oil

11. Oil after dispersant application

13. Source oiloil at depth

14. oil on surface

15. dispersed oil at depth

16. dispersed oil on surfaceWeathered oilsdissolved and modified oils at depth

17. dispersed weathered oils on surface

18. dispersed dissolved and modified oil at depth

19. dispersed weathered oil on surfaceDispersedImpactsEcological

20. Geological

21. Economic

22. SociologicalSource

23. The Effects of Weathering on Spilled OilDaysWeeksMonthsSurface Oil WeatheringStickyFloatingSinking?GunkyFloatingSinkingToxic & StickyFloatingTarball NuisanceLoss of Light Ends Saturates and Aromatics DegradedAsphaltene Residue

24. Oxidation-replace H with more electronegative elementReduction- replace electronegative element with HSlowchlorocarbonsO2+ microorganismsHYDROCARBONS“e” donorfastCO2CH4Oxidized formReduced formaerobicanaerobicno O2 very very slowHYDROCARBONSChlorocarbons“e” acceptorFast (relatively!)

25. Three Scenarioswhat’s going to happen?Best CaseNo further leaks with little or no permanent effect to the environment and food chainNature cleans environment with limited human intervention Worst Case could encompass one or more of the following: Further substantial leakageLong term changes to food chainToxicity and oxygen depletionMost Likely OutcomeGulf spill follows the scenario set by the Valdez spill (gradual return 3-5 yrs)Variables:Environmental (temperature and weather) conditionsGreater use of dispersants and ISBDepth of spill and dispersant use at depthDanger of over-remediation

26. Exxon Valdez Oil SpillRecovery

27. Oil WeatheringExxon Valdezoil weatheringstickyToxic & stickyTarball nuisance

28. Chemical ContaminationMost of the oiled mussels were as clean as unoiled mussels by 1992-93 (3-4 years)

29. Valdez/Ixtoc1 and other oil spills lessons learned: Most but not all environmental indicators return to normal in 3-5 annual cycles.

30. Oil Spills are acute events, not a chronic eventsOil Removal Options: 3 tools in Toolbox:Chemical

31. Mechanical

32. In-situ burningISB