Long-Term Persistence of Dispersants following the Deepwater Horizon Oil Spill

White, Helen K.; Lyons, Shelby; Harrison, Sarah; Findley, David M.; Liu, Yina; Kujawinski, Elizabeth B.

doi:10.1021/ez500168r

Cited by 95 publications

(81 citation statements)

References 30 publications

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“…These findings suggest that the lasting benthic impact of deep-sea spills may be minimized by measures that drive oil to stay suspended in smaller droplets for longer-an intended mode of action of the 2.9 × 10 6 L of chemical dispersant applied directly at the wellhead during the spill. While it is not known to what extent dispersant drove oil into microdroplets that biodegraded while remaining suspended in the ocean's interior, the identification of the dispersant's active ingredient in the deep ocean intrusion layers (6) and in benthic oil deposits (4) suggests that the dispersant did remain in suspension with the oil. Furthermore, roller-tank experiments with Macondo oil (19) demonstrated that dispersant delayed the formation of marine snow, perhaps through a direct influence on the surface-layer properties of oil particles or an effect on the microbial release of aggregation-promoting exudates.…”

Section: Discussionmentioning

confidence: 99%

“…A recent study questions the efficacy of the subsea dispersant application in modulating droplet size (55), and the variable impacts of dispersant on biodegradation are at the center of an ongoing debate (56,57). The effect of dispersant itself on the benthos is not well understood, but components of dispersant have been found to persist in sediments and in fragile deep-sea coral communities on a scale of years (4). Decisions regarding the use of dispersant in future spills thus need to weigh not only endpoint hydrocarbon concentration but also context: The net environmental impact of years-long exposure to high local concentrations of undispersed sediment-bound oil may or may not be more severe than the combined effects of short-term exposure of the deep water column to microdroplets of oil and dispersant and long-term exposure of sediments to their residues.…”

Section: Discussionmentioning

confidence: 99%

“…The spill was noteworthy not only for its volume but also for its distance offshore and its depth: Oil and gas entered the ocean at a water depth of ∼1,500 m and then partitioned between the deep ocean and the sea surface. This partitioning may have varied over time because of reservoir depressurization and deliberate interventions such as the shearing of the riser pipe and the application of chemical dispersant at the wellhead (4)(5)(6). In all, approximately half of the oil ascended to the ocean surface (1,7), where it was skimmed or flared by response teams, trapped in sinking particles by marine oil snow sedimentation and flocculent accumulation (8,9), washed ashore, or left exposed to the canonical weathering processes of evaporation, biodegradation, and photooxidation (7,10).…”

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confidence: 99%

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Persistence and biodegradation of oil at the ocean floor following Deepwater Horizon

Bagby

Reddy

Aeppli

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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The 2010 Deepwater Horizon disaster introduced an unprecedented discharge of oil into the deep Gulf of Mexico. Considerable uncertainty has persisted regarding the oil’s fate and effects in the deep ocean. In this work we assess the compound-specific rates of biodegradation for 125 aliphatic, aromatic, and biomarker petroleum hydrocarbons that settled to the deep ocean floor following release from the damaged Macondo Well. Based on a dataset comprising measurements of up to 168 distinct hydrocarbon analytes in 2,980 sediment samples collected within 4 y of the spill, we develop a Macondo oil “fingerprint” and conservatively identify a subset of 312 surficial samples consistent with contamination by Macondo oil. Three trends emerge from analysis of the biodegradation rates of 125 individual hydrocarbons in these samples. First, molecular structure served to modulate biodegradation in a predictable fashion, with the simplest structures subject to fastest loss, indicating that biodegradation in the deep ocean progresses similarly to other environments. Second, for many alkanes and polycyclic aromatic hydrocarbons biodegradation occurred in two distinct phases, consistent with rapid loss while oil particles remained suspended followed by slow loss after deposition to the seafloor. Third, the extent of biodegradation for any given sample was influenced by the hydrocarbon content, leading to substantially greater hydrocarbon persistence among the more highly contaminated samples. In addition, under some conditions we find strong evidence for extensive degradation of numerous petroleum biomarkers, notably including the native internal standard 17α(H),21β(H)-hopane, commonly used to calculate the extent of oil weathering.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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confidence: 99%

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Persistence and biodegradation of oil at the ocean floor following Deepwater Horizon

Bagby

Reddy

Aeppli

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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“…This early stress response was strongest in response to dispersed oil at the targeted test concentration (25 mg mL -1 ). While predicting point concentrations of oil and dispersant during a spill is difficult, impact assessments of oil spills should consider the effects of prolonged exposure to both oil and the diluted toxicants used in the chemical dispersion of oil (Goodbody-Gringley et al, 2013;White et al, 2014).…”

Section: Resultsmentioning

confidence: 99%

Stress response of the black coral Leiopathes glaberrima when exposed to sub-lethal amounts of crude oil and dispersant

Ruiz‐Ramos

Fisher

Baums

2017

Elementa: Science of the Anthropocene

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Ruiz-Ramos, DV, et al. 2017 Stress response of the black coral Leiopathes glaberrima when exposed to sub-lethal amounts of crude oil and dispersant. Elem Sci Anth, 5: 77. DOI: https://doi.org/10.1525/elementa.261 Introduction Drilling for hydrocarbons causes physical damage to the seafloor and inevitable habitat disruption to deep-sea communities (Brooke and Schroeder, 2007). Damage to the seafloor results from the installation of infrastructure, drilling discharges (muds and cuttings), and spills (Jones and Gates, 2010; Purser and Thomsen, 2012). Impacts include the loss of physical habitat, decline in species diversity and abundance, and disruption of settlement and recruitment of benthic fauna (Jones and Gates, 2010;Trannum et al., 2010; Järnegren et al., 2017). Oil spills on the outer continental shelf in the Gulf of Mexico have increased in recent years, mainly due to hurricanes and the Deepwater Horizon disaster (Anderson et al., 2012). Although cold-water corals are often found in association with drilling areas (Roberts and Aharon, 1994; Fisher et al., 2007), little is known about the impact of oil exposure on the health and survival of the corals.An unprecedented opportunity to study the potential consequences of oil spills on deep/cold water corals (reviewed in Fisher et al., 2014) came with the 2010 oil spill in lease block MC252, which released approximately 4.4 million barrels of oil into the Gulf of Mexico (Camilli et al., 2010). Surveys after this spill found oil-impacted coral colonies in at least three coral communities within 25 km of the MC252 wellhead (White et al., 2012; Fisher et al., 2014). In addition to crude oil, corals were exposed to the chemical dispersant Corexit 9500 A (DeLeo et al., 2015). As part of the mitigation strategy, 771,272 gallons of Corexit 9500 A were injected directly into the wellhead at 1544 m and 1,072,514 gallons were sprayed on the surface (Graham et al., 2011). The Macondo oil spill was unique in the amount of oil released, the depth of RESEARCH ARTICLEStress response of the black coral Leiopathes glaberrima when exposed to sub-lethal amounts of crude oil and dispersant The 2010 Deep Water Horizon oil well failure released billions of gallons of crude oil into the deep Gulf of Mexico, and, combined with chemical dispersants, this oil caused significant coral mortality. However, the mechanisms by which oil and dispersed oil impact deep marine fauna are not well understood. Here, we investigate the effects of oil and dispersed oil on a black coral common in the deep Gulf of Mexico, Leiopathes glaberrima. This coral occurs in several color morphs that show ecological and genetic differences. We hypothesized that dispersed oil would be more detrimental to coral health than oil alone and that this difference would be detectable in the gene expression response of the colonies even at sub-lethal concentrations. In two experiments, four and six colonies of red and white color morphs were exposed to oil, dispersant, and dispersed oil for a minimum of 96 hours. Vis...

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“…At this site, most colonies were at least partially covered in a brown flocculent material that contained traces of oil from the Macondo well (White et al 2012a, Hsing et al 2013. Subsequent work on material removed from the corals showed that it also contained dioctyl sodium sulfosuccinate, a compound diagnostic of the dispersant deployed during the spill (White et al 2014). In 2011, 2 additional affected communities were discovered (Fisher et al 2014).…”

Section: Introductionmentioning

confidence: 97%

Mutualistic symbiosis with ophiuroids limited the impact of the Deepwater Horizon oil spill on deep-sea octocorals

Girard

Fisher³

2016

Mar. Ecol. Prog. Ser.

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Deep-water corals form structurally complex biological habitats in the deep-sea that are generally associated with a diverse fauna. Yet, little is known about the effect of symbionts on coral resilience to natural or anthropogenic impacts. This study focused on the influence of the ophiuroid symbiont Asteroschema clavigerum on the resilience of its octocoral host Paramuricea biscaya after the Deepwater Horizon oil spill in the Gulf of Mexico. Corals were imaged between 2011 and 2014 at 4 sites, 3 of which were impacted by the spill. Each colony was digitized to quantify the impact on corals. We developed a method to define an area under the influence of ophiuroids for each coral colony. The level of total visible impact, as well as recovery, was then compared within and outside this area. For the majority of colonies, recovery from visible impact and hydroid colonization was negatively correlated with distance from the ophiuroid. Total visible impact was lower within the area influenced by ophiuroids, and branches within this area were more likely to recover. These results indicate that P. biscaya benefits from its association with A. clavigerum, likely through the physical action of ophiuroids removing material depositing on polyps, and perhaps inhibiting the settlement of hydroids. Although the beneficial role of the ophiuroids was demonstrated on corals affected by an oil spill, we suggest that these benefits would also extend to corals in environments exposed to natural sedimentation events, perhaps allowing the corals to live in environments where sedimentation would otherwise limit their survival.

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Long-Term Persistence of Dispersants following the Deepwater Horizon Oil Spill

Cited by 95 publications

References 30 publications

Persistence and biodegradation of oil at the ocean floor following Deepwater Horizon

Persistence and biodegradation of oil at the ocean floor following Deepwater Horizon

Stress response of the black coral Leiopathes glaberrima when exposed to sub-lethal amounts of crude oil and dispersant

Mutualistic symbiosis with ophiuroids limited the impact of the Deepwater Horizon oil spill on deep-sea octocorals

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