Changes in Redox Conditions of Surface Sediments Following the Deepwater Horizon and Ixtoc 1 Events
Following the blowout of the Macondo well, a sedimentation pulse resulted in significant changes in sedimentary redox conditions. This is demonstrated by downcore and temporal changes in the concentration of redox-sensitive metals: Mn and Re. Sediment cores collected in the NE Gulf of Mexico reveal increased sedimentation after the Deepwater Horizon (DWH) blowout. The formation of mucous-rich marine snow in surface waters and subsequent rapid deposition to sediments is the likely cause. Respiration of this material resulted in decreased pore-water oxygen and a shoaled redoxcline, resulting in two distinct Mn peaks in sediments following the event, one typically in the top 5–7 mm, with the other at 20–30 mm. Cores near the wellhead reveal this nonsteady-state behavior for 3–5 years after the event. A time series reveals that bulk sediment Re increased 3–4 times compared to the pre-impact baseline value for 2–3 years indicating sediments are increasingly more reducing. Three years after the blowout, subsurface Re reaches a plateau suggesting a return to steady-state conditions. In select sites where benthic foraminifera were counted, an assemblage-wide decrease is coincident with reducing conditions, demonstrating the important consequences of changing redox conditions on benthic ecosystems.
Another major submarine blowout in the southern Gulf of Mexico (Ixtoc 1; 1979–1980) released a large volume of crude oil below the surface. We observe multiple Mn oxide peaks associated with a shoaling redoxcline and Re maxima associated with more reducing conditions. Nonsteady-state behavior at sites near DWH and Ixtoc 1 is consistent with a MOSSFA (marine oil snow sedimentation and flocculent accumulation) event at both locations.
KeywordsOil spill Gulf of Mexico Deepwater Horizon Redox Trace metal Rhenium Manganese
Many thanks to the numerous Eckerd College undergraduate students who helped in the laboratory and at sea including Brigid Carr, Shannon Hammaker, Chloe Holzinger, Farley Miller, Claire Miller, and Corday Selden. Grateful acknowledgments to Alan Shiller, who provided important insight at a critical time. We are grateful to the exceptional crew of the R/V Weatherbird II for their skilled help at sea collecting samples and staying safe during the field operations.
This research was made possible by funding from The Gulf of Mexico Research Initiative to the Center for the Integrated Modeling and Analysis of the Gulf Ecosystem (C-IMAGE) Consortium Deep and the Deep Sea to Coast Connectivity in the Eastern Gulf of Mexico (Deep-C) Consortium. We also acknowledge partial funding for summer student support from Eckerd College NSSRP program. The complete data set, including all elements determined by ICP-MS, can be accessed at the GRIIDC website: https://data.gulfresearchinitiative.org/ (doi: 10.7266/N7DN43JM; 10.7266/N7C24TD; 10.7266/N7RX9914).
- Boyko T, Baturin G, Miller A (1986) Rhenium in recent ocean sediments. Geochem Int 23:38–47Google Scholar
- Brooks GR, Larson RA, Schwing PT, Romero I, Moore C, Reichart G-J, Jilbert T, Chanton JP, Hastings DW, Overholt WA, Marks KP, Kostka JE, Holmes CW, Hollander D (2015) Sedimentation Pulse in the NE Gulf of Mexico following the 2010 DWH Blowout. PLoS One 10(7):e0132341. https://doi.org/10.1371/journal.pone.0132341CrossRefGoogle Scholar
- Bruce P. Finney, Mitchell W. Lyle, G. Ross Heath, (1988) Sedimentation at MANOP Site H (eastern equatorial Pacific) over the past 400,000 years: Climatically induced redox variations and their effects on transition metal cycling.Paleoceanography 3 (2):169–189Google Scholar
- Davis JE (2017) The Gulf: the making of an American Sea. Liveright Publishing, New YorkGoogle Scholar
- EPA (1994) Microwave assisted acid digestion of sediments, sludges, soils, and oils, Method 3051. U.S. Government Printing Office, Washington, DCGoogle Scholar
- Hastings DW, Schwing PT, Brooks GR, Larson RA, Morford JL, Roeder T, Quinn KA, Bartlett T, Romero IC, Hollander DJ (2016) Changes in sediment redox conditions following the BP DWH blowout event. Deep-Sea Res II Top Stud Oceanogr 129:167–178. https://doi.org/10.1016/j.dsr2.2014.12.009CrossRefGoogle Scholar
- Joye SB, MacDonald IR, Leifer I, Asper V (2011) Magnitude and oxidation potential of hydrocarbon gases released from the BP oil well blowout. Nat Geosci 4(3):160–164. http://www.nature.com/ngeo/journal/v4/n3/abs/ngeo1067.html#supplementary-informationCrossRefGoogle Scholar
- Larson RA, Brooks GR, Schwing PT, Diercks AR, Holmes CW, Chanton JP, Diaz-Asencio M, Hollander DJ (2020) Characterization of the sedimentation associated with the Deepwater Horizon blowout: depositional pulse, initial response, and stabilization (Chap. 14). In: Murawski SA, Ainsworth C, Gilbert S, Hollander D, Paris CB, Schlüter M, Wetzel D (eds) Scenarios and responses to future deep oil spills – fighting the next war. Springer, ChamGoogle Scholar
- Quigg A, Passow U, Hollander DJ, Daly KL, Burd A, Lee K (2020) Formation and sinking of MOSSFA (marine oil snow sedimentation and flocculent accumulation) events: past and present (Chap. 12). In: Murawski SA, Ainsworth C, Gilbert S, Hollander D, Paris CB, Schlüter M, Wetzel D (eds) Deep oil spills – facts, fate and effects. Springer, ChamGoogle Scholar
- Romero IC, Chanton JP, Rosenheim BE, Radović J, Schwing PT, Hollander DJ, Larter SR, Oldenburg TBP (2020) Long-term preservation of oil spill events in sediments: the case for the Deepwater Horizon Spill in the Northern Gulf of Mexico (Chap. 17). In: Murawski SA, Ainsworth C, Gilbert S, Hollander D, Paris CB, Schlüter M, Wetzel D (eds) Deep oil spills – facts, fate and effects. Springer, ChamGoogle Scholar
- Schwing PT, Hollander DJ, Brooks GR, Larson RA, Hastings DW, Chanton JP, Lincoln SA, Radović JR, Langenhoff A (2020) The sedimentary record of MOSSFA events in the Gulf of Mexico: a comparison of the Deepwater Horizon (2010) and Ixtoc 1 (1979) oil spills (Chap. 13). In: Murawski SA, Ainsworth C, Gilbert S, Hollander D, Paris CB, Schlüter M, Wetzel D (eds) Deep oil spills – facts, fate and effects. Springer, ChamGoogle Scholar
- Schwing PT, Machain Castillo ML (2020) Impact and resilience of benthic foraminifera in the aftermath of the Deepwater Horizon and Ixtoc 1 oil spills (Chap. 23). In: Murawski SA, Ainsworth C, Gilbert S, Hollander D, Paris CB, Schlüter M, Wetzel D (eds) Deep oil spills – facts, fate and effects. Springer, ChamGoogle Scholar
- Schwing PT, Romero IC, Larson RA, O'Malley BJ, Fridrik EE, Goddard EA, Brooks GR, Hastings DW, Rosenheim BE, Hollander DJ, Grant G, Mulhollan J (2016) Sediment core extrusion method at millimeter resolution using a calibrated, threaded-rod. J Vis Exp (114):54363. https://doi.org/10.3791/54363
- U.S. District Court Findings of Facts and Conclusions of Law –Phase 2 Trial. Case 2: 10-md- 02179-cjb-ss, pp 1e44. Document 14021 Filed Jan. 15, 2015. http://www.laed.uscourts.gov/sites/default/files/OilSpill/Orders/1152015FindingsPhaseTwo.pdf
- Ziervogel K, McKay L, Rhodes B, Osburn CL, Dickson-Brown J, Arnosti C, Teske A (2012) Microbial activities and dissolved organic matter dynamics in oil-contaminated surface seawater from the Deepwater Horizon oil spill site. PLoS One 7(4):e34816. https://doi.org/10.1371/journal.pone.0034816CrossRefGoogle Scholar