Meta-analysis of salt marsh vegetation impacts and recovery: a synthesis following the Deepwater Horizon oil spill

Recent advances in Emulsan production, purification, and application: Exploring bioemulsifiers unique potentials

Bioemulsifiers are compounds produced by microorganisms that reduce the interfacial forces between hydrophobic substances and water. Due to their potential in the pharmaceutical and food industries and their efficiency in oil spill remediation, they have been the subject of study in the scientific community while being safe, biodegradable, and sustainable compared to synthetic options. These biomolecules have high molecular weight and polymeric structures, distinguishing them from traditional biosurfactants. Emulsan, a bioemulsifier exopolysaccharide, is produced by Acinetobacter strains and is highly efficient in forming stable emulsions. Its low toxicity and high potential as an emulsifying agent promote its application in pharmaceutical and food industries as a drug-delivery vehicle and emulsion stabilizer. Due to the high environmental impact of oil spills, bioemulsifiers have great potential for environmental applications, such as bioremediation. This unique feature gives them a distinct mechanism of action in forming emulsions, resulting in minimal environmental impact. A better understanding of these aspects can improve the use of bioemulsifiers and environmental remediation in various industries. This review will discuss the production and characterization of Emulsan, focusing on recent advancements in cultivation conditions, purification techniques, compound identification, and ecotoxicity.

Bioemulsifier production by Acinetobacter venetianus AMO1502: Potential for bioremediation and environmentally friendly applications

At the best conditions of the bioprocess (30 °C, pH 7.0, 3.0 g/L NaCl) were obtained 0.66 g/L cell concentration, 3.3 g/L of bioemulsifier, which showed high emulsifying activity (53 % ± 2), reducing the surface tension of the water in 47.2 % (38 mN/m). The polymeric structure of the purified bioemulsifier comprised a carbohydrate backbone composed of hexose-based amino sugars with a monomeric mass of 1099 Da, structurally similar to emulsan. A. venetianus bioemulsifier is non-phytotoxic (GI% > 80 %) against Ocimum basilicum and Brassica oleracea and non-cytotoxic (LC50 5794 mg/L) against Artemia salina, being safe local organisms in comparison to other less eco-friendly synthetic emulsifiers. This bioemulsifier effectively dispersed spilled oil in vitro (C22-C33), reducing oil mass by 12 % (w/w) and dispersing oil in a displacement area of 75 cm2 (23.8 % of the spilled area). Thus, the isolated A. venetianus AMO1502 produced a bioemulsifier potentially applicable for environmentally friendly oil spill remediation.

Disturbance legacies and shifting trajectories: Marsh soil strength and shoreline erosion a decade after the Deepwater Horizon oil spill

Marsh resilience post disturbance is strongly dependent on the belowground dynamics affecting the emergent plants aboveground. We investigated the long-term impacts at the marsh-water interface in coastal wetlands of south Louisiana after the 2010 Deepwater Horizon oil spill with a combination of fieldwork (2010-2018) and spatial analysis (1998-2021). Data were collected on shoreline erosion rates, marsh platform elevation heights and cantilever overhang widths, and soil strength up to 1 m depth. Oil concentration in the top 5 cm of the marsh soil were determined using gas chromatography/mass spectrometry and were 1000 times higher than before the spill and remained 10 times higher eight years post-oiling. The oiling initially caused the marsh edge to subside, and chronic effects lowered soil strength, creating a faster erosion rate and deeper water within 150 cm of the shoreline. Soil strength declined by 50% throughout the 1 m soil profile after oiling and has not recovered. The mean erosion rate for 11 years post-spill was double that before oiling and there was an additive impact on erosion rates after Hurricane Isaac. Erosion appeared to have recovered to pre-spill rates by 2019, however from 2019 to 2021, the rate increased by 118% above the pre-spill rate. The continuing loss of soil strength indicates that the belowground biomass was seriously compromised by oiling. The perpetuation of oil in the remaining marsh may have set a new baseline for soil strength and subsequent storm induced erosional events. The remaining marsh soils retain chronic physical and biological legacies compromising recovery for more than a decade that may be evident in other marsh habitats subject to oiling and other stressors.

Emerging bio-dispersant and bioremediation technologies as environmentally friendly management responses toward marine oil spill: A comprehensive review

Marine oil spills emanating from wells, pipelines, freighters, tankers, and storage facilities draw public attention and necessitate quick and environmentally friendly response measures. It is sometimes feasible to contain the oil with booms and collect it with skimmers or burn it, but this is impracticable in many circumstances, and all that can be done without causing further environmental damage is adopting natural attenuation, particularly through microbial biodegradation. Biodegradation can be aided by carefully supplying biologically accessible nitrogen and phosphorus to alleviate some of the microbial growth constraints at the shoreline. This review discussed the characteristics of oil spills, origin, ecotoxicology, health impact of marine oils spills, and responses, including the variety of remedies and responses to oil spills using biological techniques. The different bioremediation and bio-dispersant treatment technologies are then described, with a focus on the use of green surfactants and their advances, benefits/drawbacks. These technologies were thoroughly explained, with a timeline of research and recent studies. Finally, the hurdles that persist as a result of spills are explored, as well as the measures that must be taken and the potential for the development of existing treatment technologies, all of which must be linked to the application of integrated procedures.

Accelerated marsh erosion following the Deepwater Horizon oil spill confirmed, ameliorated by planting

Multiple studies have examined the effects of the Deepwater Horizon oil spill on coastal marsh shoreline erosion. Most studies have concluded that the spill increased shoreline erosion (linear retreat) in oiled marshes by ~ 100–200% for at least 2–3 years. However, two studies have called much of this prior research into question, due to potential study design flaws and confounding factors, primarily tropical cyclone influences and differential wave exposure between oiled (impact) and unoiled (reference) sites. Here we confirm that marsh erosion in our field experiment was substantially increased (112–233%) for 2 years in heavily oiled marsh after the spill, likely due to vegetation impacts and reduced soil shear strength attributed to the spill, rather than the influences of hurricanes or wave exposure variation. We discuss how our findings reinforce prior studies, including a wider-scale remote sensing analysis with similar study approach. We also show differences in the degree of erosion among oil spill cleanup treatments. Most importantly, we show that marsh restoration planting can drastically reduce oiled marsh erosion, and that the positive influences of planting can extend beyond the immediate impact of the spill.

Coping with oil spills: oil exposure and anxiety among residents of Gulf Coast states after the Deepwater Horizon Oil Spill

In April 2010, a fatal explosion on the Deepwater Horizon drilling rig in the Gulf of Mexico resulted in the largest marine oil spill in history. This research describes the association of oil exposure with anxiety after the Deepwater Horizon Oil Spill and evaluates effect modification by self-mastery, emotional support and cleanup participation. To assess the impacts of the Deepwater Horizon Oil Spill, the Centers for Disease Control and Prevention (CDC) conducted the Gulf States Population Survey (GSPS), a random-digit-dial telephone cross-sectional survey completed between December 2010 and December 2011 with 38,361 responses in four different Gulf Coast states: Louisiana, Florida, Alabama and Mississippi. Anxiety severity was measured using the Generalised Anxiety Disorder (GAD) symptom inventory. We used Tobit regression to model underlying anxiety as a function of oil exposure and hypothesised effect modifiers, adjusting for socio-demographics. Latent anxiety was higher among those with direct contact with oil than among those who did not have direct contact with oil in confounder-adjusted models [β = 2.84, 95% confidence interval (CI): 0.78, 4.91]. Among individuals with direct contact with oil, there was no significant interaction between participating in cleanup activities and emotional support for anxiety (p = 0.20). However, among those with direct contact with oil, in confounder-adjusted models, participation in oil spill cleanup activities was associated with lower latent anxiety (β = -3.55, 95% CI: -6.15, -0.95). Oil contact was associated with greater anxiety, but this association appeared to be mitigated by cleanup participation.