Level and Degradation of Deepwater Horizon Spilled Oil in Coastal Marsh Sediments and Pore-Water

Natter, Michael; Keevan, Jeff; Wang, Yan; Keimowitz, Alison R.; Okeke, Benedict C.; Son, Ahjeong; Lee, Ming Kuo

doi:10.1021/es300058w

Cited by 75 publications

(53 citation statements)

References 39 publications

(64 reference statements)

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“…The CPI values were also significantly different in 2013 compared to in 2010 and 2011 (see Table S2f in the supplemental material), but the Pr/Phy ratios increased and were comparable to May 2010 prespill ratios, thereby suggesting alkane degradation (63,68). Evidence of biodegradation was noted by others (38,40,69,70). By June 2013, the concentrations of n-alkanes and PAHs were 1 and 5%, respectively, of early 2011 concentrations, which confirmed that petroleum hydrocarbons were still present in the marshes, but at lower levels likely due to sediment sequestration, weathering, and degradation (68).…”

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confidence: 63%

“…Initially, some DWH spill researchers proposed a swift microbial response (16,17) because microbes have the capacity to degrade constituent carbon compounds in oil (31)(32)(33)(34)(35) and earlier nutrient enrichment, metal exposure, and oiling experiments provided evidence that marsh communities could withstand low levels of disturbance from an oil spill (25,36). Short-duration studies based on research conducted during one sampling time or from Ͻ6 to 9 months of sampling events in 2010 and 2011 confirmed that the relative abundances and species richness for bacterial communities exposed to weathered oil residues changed through time and recognized a greater diversity among known hydrocarbon-degrading bacteria as the amount of petroleum hydrocarbon concentrations increased (37)(38)(39)(40). Although a cascading series of long-term biogeochemical consequences, due to the microbial response, was anticipated for the marsh ecosystem (41), some of the earlier studies suggested a faster-than-expected recovery (16,42).…”

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confidence: 93%

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Salt Marsh Bacterial Communities before and after the Deepwater Horizon Oil Spill

Engel

Liu

Paterson

et al. 2017

Appl Environ Microbiol

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Coastal salt marshes along the northern Gulf of Mexico shoreline received varied types and amounts of weathered oil residues after the 2010 Deepwater Horizon oil spill. At the time, predicting how marsh bacterial communities would respond and/or recover to oiling and other environmental stressors was difficult because baseline information on community composition and dynamics was generally unavailable. Here, we evaluated marsh vegetation, physicochemistry, flooding frequency, hydrocarbon chemistry, and subtidal sediment bacterial communities from 16S rRNA gene surveys at 11 sites in southern Louisiana before the oil spill and resampled the same marshes three to four times over 38 months after the spill. Calculated hydrocarbon biomarker indices indicated that oil replaced native natural organic matter (NOM) originating from Spartina alterniflora and marine phytoplankton in the marshes between May 2010 and September 2010. At all the studied marshes, the major class-and order-level shifts among the phyla Proteobacteria, Firmicutes, Bacteroidetes, and Actinobacteria occurred within these first 4 months, but another community shift occurred at the time of peak oiling in 2011. Two years later, hydrocarbon levels decreased and bacterial communities became more diverse, being dominated by Alphaproteobacteria (Rhizobiales), Chloroflexi (Dehalococcoidia), and Planctomycetes. Compositional changes through time could be explained by NOM source differences, perhaps due to vegetation changes, as well as marsh flooding and salinity excursions linked to freshwater diversions. These findings indicate that persistent hydrocarbon exposure alone did not explain long-term community shifts. IMPORTANCE Significant deterioration of coastal salt marshes in Louisiana has been linked to natural and anthropogenic stressors that can adversely affect how ecosystems function. Although microorganisms carry out and regulate most biogeochemical reactions, the diversity of bacterial communities in coastal marshes is poorly known, with limited investigation of potential changes in bacterial communities in response to various environmental stressors. The Deepwater Horizon oil spill provided an unprecedented opportunity to study the long-term effects of an oil spill on microbial systems in marshes. Compared to previous studies, the significance of our research stems from (i) a broader geographic range of studied marshes, (ii) an extended time frame of data collection that includes prespill conditions, (iii) a more accurate procedure using biomarker indices to understand oiling, and (iv) an examination of other potential stressors linked to in situ environmental changes, aside from oil exposure.

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confidence: 63%

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confidence: 93%

Salt Marsh Bacterial Communities before and after the Deepwater Horizon Oil Spill

Engel

Liu

Paterson

et al. 2017

Appl Environ Microbiol

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“…The most abundant microorganisms enriched both in the anodic and in the bulk communities were SRB, some of which were phylogenetically related to known anaerobic hydrocarbon degraders. This is logical if the environmental conditions are taken into account; oxygen is quickly depleted when an oil spill occurs due to the prominent presence of organic matter (75), while under anaerobic conditions sulfate reduction typically is enhanced (75). Toluene degradation rates under sulfate-reducing conditions can vary by orders of magnitude.…”

Section: Discussionmentioning

confidence: 99%

Anodes Stimulate Anaerobic Toluene Degradation via Sulfur Cycling in Marine Sediments

Daghio

Vaiopoulou

Patil

et al. 2016

Appl Environ Microbiol

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cHydrocarbons released during oil spills are persistent in marine sediments due to the absence of suitable electron acceptors below the oxic zone. Here, we investigated an alternative bioremediation strategy to remove toluene, a model monoaromatic hydrocarbon, using a bioanode. Bioelectrochemical reactors were inoculated with sediment collected from a hydrocarbon-contaminated marine site, and anodes were polarized at 0 mV and ؉300 mV (versus an Ag/AgCl [3 M KCl] reference electrode). The degradation of toluene was directly linked to current generation of up to 301 mA m ؊2 and 431 mA m ؊2 for the bioanodes polarized at 0 mV and ؉300 mV, respectively. Peak currents decreased over time even after periodic spiking with toluene. The monitoring of sulfate concentrations during bioelectrochemical experiments suggested that sulfur metabolism was involved in toluene degradation at bioanodes. 16S rRNA gene-based Illumina sequencing of the bulk anolyte and anode samples revealed enrichment with electrocatalytically active microorganisms, toluene degraders, and sulfate-reducing microorganisms. Quantitative PCR targeting the ␣-subunit of the dissimilatory sulfite reductase (encoded by dsrA) and the ␣-subunit of the benzylsuccinate synthase (encoded by bssA) confirmed these findings. In particular, members of the family Desulfobulbaceae were enriched concomitantly with current production and toluene degradation. Based on these observations, we propose two mechanisms for bioelectrochemical toluene degradation: (i) direct electron transfer to the anode and/or (ii) sulfide-mediated electron transfer.

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“…As a result, salt marsh organisms were exposed to weathered and dispersed 74 sweet crude oil, and oil-derived compounds (Natter et al, 2012;Stout et al, 2016). This resulted 75 in extensive mortality of saltmarsh plants, particularly in heavily oiled areas (Lin and 76 Mendelssohn, 2012).…”

Section: Introduction 70mentioning

confidence: 99%

Ultraviolet radiation significantly enhances the molecular response to dispersant and sweet crude oil exposure in Nematostella vectensis

Tarrant

Payton

Reitzel

et al. 2018

Marine Environmental Research

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35Estuarine organisms are subjected to combinations of anthropogenic and natural stressors, 36 which together can reduce an organisms' ability to respond to either stress or can potentiate or 37 synergize the cellular impacts for individual stressors. Nematostella vectensis (starlet sea 38 anemone) is a useful model for investigating novel and evolutionarily conserved cellular and 39 molecular responses to environmental stress. Using RNA-seq, we assessed global changes in gene 40 expression in Nematostella in response to dispersant and/or sweet crude oil exposure alone or 41

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Level and Degradation of Deepwater Horizon Spilled Oil in Coastal Marsh Sediments and Pore-Water

Cited by 75 publications

References 39 publications

Salt Marsh Bacterial Communities before and after the Deepwater Horizon Oil Spill

Salt Marsh Bacterial Communities before and after the Deepwater Horizon Oil Spill

Anodes Stimulate Anaerobic Toluene Degradation via Sulfur Cycling in Marine Sediments

Ultraviolet radiation significantly enhances the molecular response to dispersant and sweet crude oil exposure in Nematostella vectensis

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