Immediate ecotoxicological effects of short-lived oil spills on marine biota

Finding the needle in a haystack: Evaluation of ecotoxicological effects along the continental shelf break during the Brazilian mysterious oil spill

Oceanic oil spills present significant ecological risks that have the potential to contaminate extensive areas, including coastal regions. The occurrence of the 2019 oil spill event in Brazil resulted in over 3000 km of contaminated beaches and shorelines. While assessing the impact on benthic and beach ecosystems is relatively straightforward due to direct accessibility, evaluating the ecotoxicological effects of open ocean oil spills on the pelagic community is a complex task. Difficulties are associated with the logistical challenges of responding promptly and, in case of the Brazilian mysterious oil spill, to the subsurface propagation of the oil that impeded remote visual detection. An oceanographic expedition was conducted in order to detect and evaluate the impact of this oil spill event along the north-eastern Brazilian continental shelf. The pursuit of dissolved and dispersed oil compounds was accomplished by standard oceanographic methods including seawater polycyclic aromatic hydrocarbons (PAHs) analysis, biomass stable carbon isotope (δ13C), particulate organic carbon to particulate organic nitrogen (POC:PON) ratios, nutrient analysis and ecotoxicological bioassays using the naupliar phase of the copepod Tisbe biminiensis. Significant ecotoxicological effects, reducing naupliar development by 20-40 %, were indicated to be caused by the presence of dispersed oil in the open ocean. The heterogeneous distribution of oil droplets aggravated the direct detection and biochemical indicators for oil are presented and discussed. Our findings serve as a case study for identifying and tracing subsurface propagation of oil, demonstrating the feasibility of utilizing standard oceanographic and ecotoxicological methods to assess the impacts of oil spill events in the open ocean. Ultimately, it encourages the establishment of appropriate measures and responses regarding the liability and regulation of entities to be held accountable for oil spills in the marine environment.

Novel, active, and uncultured hydrocarbon-degrading microbes in the ocean

Given the vast quantity of oil and gas input to the marine environment annually, hydrocarbon degradation by marine microorganisms is an essential ecosystem service. Linkages between taxonomy and hydrocarbon degradation capabilities are largely based on cultivation studies, leaving a knowledge gap regarding the intrinsic ability of uncultured marine microbes to degrade hydrocarbons. To address this knowledge gap, metagenomic sequence data from the Deepwater Horizon (DWH) oil spill deep-sea plume was assembled to which metagenomic and metatranscriptomic reads were mapped. Assembly and binning produced new DWH metagenome-assembled genomes that were evaluated along with their close relatives, all of which are from the marine environment (38 total). These analyses revealed globally distributed hydrocarbon-degrading microbes with clade-specific substrate degradation potentials that have not been reported previously. For example, methane oxidation capabilities were identified in all Cycloclasticus. Furthermore, all Bermanella encoded and expressed genes for non-gaseous n-alkane degradation; however, DWH Bermanella encoded alkane hydroxylase, not alkane 1-monooxygenase. All but one previously unrecognized DWH plume member in the SAR324 and UBA11654 have the capacity for aromatic hydrocarbon degradation. In contrast, Colwellia were diverse in the hydrocarbon substrates they could degrade. All clades encoded nutrient acquisition strategies and response to cold temperatures, while sensory and acquisition capabilities were clade specific. These novel insights regarding hydrocarbon degradation by uncultured planktonic microbes provides missing data, allowing for better prediction of the fate of oil and gas when hydrocarbons are input to the ocean, leading to a greater understanding of the ecological consequences to the marine environment.IMPORTANCEMicrobial degradation of hydrocarbons is a critically important process promoting ecosystem health, yet much of what is known about this process is based on physiological experiments with a few hydrocarbon substrates and cultured microbes. Thus, the ability to degrade the diversity of hydrocarbons that comprise oil and gas by microbes in the environment, particularly in the ocean, is not well characterized. Therefore, this study aimed to utilize non-cultivation-based 'omics data to explore novel genomes of uncultured marine microbes involved in degradation of oil and gas. Analyses of newly assembled metagenomic data and previously existing genomes from other marine data sets, with metagenomic and metatranscriptomic read recruitment, revealed globally distributed hydrocarbon-degrading marine microbes with clade-specific substrate degradation potentials that have not been previously reported. This new understanding of oil and gas degradation by uncultured marine microbes suggested that the global ocean harbors a diversity of hydrocarbon-degrading bacteria, which can act as primary agents regulating ecosystem health.

Anthropogenic stressors and the marine environment: From sources and impacts to solutions and mitigation

Human-released contaminants are often poorly understood wholistically in marine ecosystems. This review examines the sources, pathways, impacts on marine animals, and mitigation strategies of five pollutants (plastics, per- and polyfluoroalkyl substances, bisphenol compounds, ethynylestradiol, and petroleum hydrocarbons). Both abiotic and biotic mechanisms contribute to all five contaminants' movement. These pollutants cause short- and long-term effects on many biological processes genetically, molecularly, neurologically, physiologically, reproductively, and developmentally. We explore the extension of adverse outcome pathways to ecosystem effects by considering known inter-generational and trophic relations resulting in large-scale direct and indirect impacts. In doing so, we develop an understanding of their roles as environmental stressors in marine environments for targeted mitigation and future work. Ecosystems are interconnected and so international collaboration, standards, measures preceding mass production, and citizen involvement are required to protect and conserve marine life.

Dilute concentrations of maritime fuel can modify sediment reworking activity of high-latitude marine invertebrates

Multiple expressions of climate change, in particular warming-induced reductions in the type, extent and thickness of sea ice, are opening access and providing new viable development opportunities in high-latitude regions. Coastal margins are facing these challenges, but the vulnerability of species and ecosystems to the effects of fuel contamination associated with increased maritime traffic is largely unknown. Here, we show that low concentrations of the water-accommodated fraction of marine fuel oil, representative of a dilute fuel oil spill, can alter functionally important aspects of the behaviour of sediment-dwelling invertebrates. We find that the response to contamination is species specific, but that the range in response among individuals is modified by increasing fuel concentrations. Our study provides evidence that species responses to novel and/or unprecedented levels of anthropogenic activity associated with the opening up of high-latitude regions can have substantive ecological effects, even when human impacts are at, or below, commonly accepted safe thresholds. These secondary responses are often overlooked in broad-scale environmental assessments and marine planning yet, critically, they may act as an early warning signal for impending and more pronounced ecological transitions.

The dispersant Corexit 9500 and (dispersed) oil are lethal to coral endosymbionts

Endosymbionts (Symbiodiniaceae) play a vital role in the health of corals. Seawater pollution can harm these endosymbionts and dispersants used during oil spill cleanup can be extremely toxic to these organisms. Here, we examined the impact of oil and a specific dispersant, Corexit-9500, on two representative endosymbionts - Symbiodinium and Cladocopium - from the Southwestern endemic coral Mussismilia braziliensis. The survival and photosynthetic potential of the endosymbionts decreased dramatically after exposure to the dispersant and oil by ~25 % after 2 h and ~50 % after 7 days. Low concentrations of dispersant (0.005 ml/l) and dispersed oil (Polycyclic Aromatic Hydrocarbons, 1132 μg/l; Total Petroleum Hydrocarbons, 595 μg/l) proved highly toxic to both Symbiodinium and Cladocopium. These levels triggered a reduction in growth rate, cell size, and cell wall thickness. After a few hours of exposure, cellular organelles were damaged or destroyed. These acute toxic effects underline the fragile nature of coral endosymbionts.

Effects of Temperature and DC Electric Fields on Perfluorooctanoic Acid Sorption Kinetics to Activated Carbon

Sorption to activated carbon is a common approach to reducing environmental risks of waterborne perfluorooctanoic acid (PFOA), while effective and flexible approaches to PFOA sorption are needed. Variations in temperature or the use of electrokinetic phenomena (electroosmosis and electromigration) in the presence of external DC electric fields have been shown to alter the contaminant sorption of contaminants. Their role in PFOA sorption, however, remains unclear. Here, we investigated the joint effects of DC electric fields and the temperature on the sorption of PFOA on activated carbon. Temperature-dependent batch and column sorption experiments were performed in the presence and absence of DC fields, and the results were evaluated by using different kinetic sorption models. We found an emerging interplay of DC and temperature on PFOA sorption, which was linked via the liquid viscosity (η) of the electrolyte. For instance, the combined presence of a DC field and low temperature increased the PFOA loading up to 38% in 48 h relative to DC-free controls. We further developed a model that allowed us to predict temperature- and DC field strength-dependent electrokinetic benefits on the drivers of PFOA sorption kinetics (i.e., intraparticle diffusivity and the film mass transfer coefficient). Our insights may give rise to future DC- and temperature-driven applications for PFOA sorption, for instance, in response to fluctuating PFOA concentrations in contaminated water streams.

Performance evaluation of rhamnolipid biosurfactant produced by Pseudomonas aeruginosa and its effect on marine oil-spill remediation

This study aimed to reveal that the effect of biosurfactant on the dispersion and degradation of crude oil. Whole genome analysis showed that Pseudomonas aeruginosa GB-3 contained abundant genes involved in biosurfactant synthesis and metabolic processes and had the potential to degrade oil. The biosurfactant produced by strain GB-3 was screened by various methods. The results showed that the surface tension reduction activity was 28.6 mN·m-1 and emulsification stability was exhibited at different pH, salinity and temperature. The biosurfactant was identified as rhamnolipid by LC-MS and FTIR. The fermentation conditions of strain GB-3 were optimized by response surface methodology, finally the optimal system (carbon source: glucose, nitrogen source: ammonium sulfate, C/N ratio:16:1, pH: 7, temperature: 30-35 °C) was determined. Compared with the initial fermentation, the yield of biosurfactant increased by 4.4 times after optimization. In addition, rhamnolipid biosurfactant as a dispersant could make the dispersion of crude oil reach 38% within seven days, which enhanced the bioavailability of crude oil. As a biostimulant, it could also improve the activity of indigenous microorganism and increase the degradation rate of crude oil by 10-15%. This study suggested that rhamnolipid biosurfactant had application prospect in bioremediation of marine oil-spill.

Marine Microbiota Responses to Shipping Scrubber Effluent Assessed at Community Structure and Function Endpoints

The use of novel high-throughput sequencing (HTS) technologies to examine the responses of natural multidomain microbial communities to scrubber effluent discharges to the marine environment is still limited. Thus, we applied metabarcoding sequencing targeting the planktonic unicellular eukaryotic and prokaryotic fraction (phytoplankton, bacterioplankton, and protozooplankton) in mesocosm experiments with natural microbial communities from a polluted and an unpolluted site. Furthermore, metagenomic analysis revealed changes in the taxonomic and functional dominance of multidomain marine microbial communities after scrubber effluent additions. The results indicated a clear shift in the microbial communities after such additions, which favored bacterial taxa with known oil and polycyclic aromatic hydrocarbons (PAHs) biodegradation capacities. These bacteria exhibited high connectedness with planktonic unicellular eukaryotes employing variable trophic strategies, suggesting that environmentally relevant bacteria can influence eukaryotic community structure. Furthermore, Clusters of Orthologous Genes associated with pathways of PAHs and monocyclic hydrocarbon degradation increased in numbers at treatments with high scrubber effluent additions acutely. These genes are known to express enzymes acting at various substrates including PAHs. These indications, in combination with the abrupt decrease in the most abundant PAHs in the scrubber effluent below the limit of detection-much faster than their known half-lives-could point toward a bacterioplankton-initiated rapid ultimate biodegradation of the most abundant toxic contaminants of the scrubber effluent. The implementation of HTS could be a valuable tool to develop multilevel biodiversity indicators of the scrubber effluent impacts on the marine environment, which could lead to improved impact assessment. Environ Toxicol Chem 2024;00:1-18. © 2024 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Cumulative Impacts of Oil Pollution, Ocean Warming, and Coastal Freshening on the Feeding of Arctic Copepods

The Arctic is undergoing rapid changes, and biota are exposed to multiple stressors, including pollution and climate change. Still, little is known about their joint impact. Here, we investigated the cumulative impact of crude oil, warming, and freshening on the copepod species Calanus glacialis and Calanus finmarchicus. Adult females were exposed to ambient conditions (control; 0 °C + 33 psu) and combined warming and freshening: 5 °C + 27 psu (Scenario 1), 5 °C + 20 psu (Scenario 2) for 6 days. All three conditions were tested with and without dispersed crude oil. In Scenario 1, fecal pellet production (FPP) significantly increased by 40-78% and 42-122% for C. glacialis and C. finmarchicus, respectively. In Scenario 2, FPP decreased by 6-57% for C. glacialis, while it fluctuated for C. finmarchicus. For both species, oil had the strongest effect on FPP, leading to a 68-83% reduction. This overshadowed the differences between climatic scenarios. All variables (temperature, salinity, and oil) had significant single effects and several joint effects on FPP. Our results demonstrate that Arctic copepods are sensitive to environmentally realistic concentrations of crude oil and climate change. Strong reductions in feeding can reduce the copepods' energy content with potential large-scale impacts on the Arctic marine food web.

Tar patties are hotspots of hydrocarbon turnover and nitrogen fixation during a nearshore pollution event in the oligotrophic southeastern Mediterranean Sea

Weathered oil, that is, tar, forms hotspots of hydrocarbon degradation by complex biota in marine environment. Here, we used marker gene sequencing and metagenomics to characterize the communities of bacteria, archaea and eukaryotes that colonized tar patties and control samples (wood, plastic), collected in the littoral following an offshore spill in the warm, oligotrophic southeastern Mediterranean Sea (SEMS). We show potential aerobic and anaerobic hydrocarbon catabolism niches on tar interior and exterior, linking carbon, sulfur and nitrogen cycles. Alongside aromatics and larger alkanes, short-chain alkanes appear to fuel dominant populations, both the aerobic clade UBA5335 (Macondimonas), anaerobic Syntropharchaeales, and facultative Mycobacteriales. Most key organisms, including the hydrocarbon degraders and cyanobacteria, have the potential to fix dinitrogen, potentially alleviating the nitrogen limitation of hydrocarbon degradation in the SEMS. We highlight the complexity of these tar-associated communities, where bacteria, archaea and eukaryotes co-exist, likely exchanging metabolites and competing for resources and space.

Tar balls as a floating substrate for long-distance species dispersal

Recent arrivals of tar balls have been observed in several tropical beaches associated with the oceanic circulation that flows to the Brazilian continental shelf. Between August and September 2022, tar balls were collected in the northeastern coast of Brazil and analyzed. Nearly 90 % of the oils were colonized by barnacles, polychaetes, decapods, and algae. Most rafting organisms were Lepas anserifera with capitulum measuring 0.32 to 22.21 mm. Based on the growth rate of barnacles and the speed of the SEC it was estimated that tar balls were floating since July and August 2022 and traveled a maximum of 1938.82 km. The organisms and tar balls' possible origin is in the international waters, near to the meso-Atlantic ridge, known for oil tanker traffic. The tar balls, in addition to the oil-related impacts, can act as a vector of long-distance species dispersion, and it needs to raise an alert, considering the possible ecological impacts.

Effects of marine diesel on microbial diversity and activity in high Arctic beach sediments

Global warming induced sea ice loss increases Arctic maritime traffic, enhancing the risk of ecosystem contamination from fuel spills and nutrient loading. The impact of marine diesel on bacterial metabolic activity and diversity, assessed by colorimetric assay, 16S rRNA and metagenomic sequencing, of Northwest Passage (Arctic Ocean) beach sediments was assessed with nutrient amendment at environmentally relevant temperatures (5 and 15 °C). Higher temperature and nutrients stimulated microbial activity, while diesel reduced it, with metabolism inhibited at and above 0.01 % (without nutrients) and at 1 % (with nutrients) diesel inclusions. Diesel exposure significantly decreased microbial diversity and selected for Psychrobacter genus. Microbial hydrocarbon degradation, organic compound metabolism, and exopolysaccharide production gene abundances increased under higher diesel concentrations. Metagenomic binning recovered nine MAGs/bins with hydrocarbon degradation genes. We demonstrate a nutrients' rescue-type effect in diesel contaminated microbial communities via enrichment of microorganisms with stress response, aromatic compound, and ammonia assimilation metabolisms.

Tracking the early signals of crude oil in seawater and plankton after a major oil spill in the Red Sea

Understanding the immediate impacts of oil spills is essential to recognizing their long-term consequences on the marine environment. In this study, we traced the early (within one week) signals of crude oil in seawater and plankton after a major oil spill in October 2019 in the Red Sea. At the time of sampling, the plume had moved eastward, but we detected significant signs of incorporation of oil carbon into the dissolved organic carbon pool, resulting in a 10-20% increase in the ultraviolet (UV) absorption coefficient (a₂₅₄) of chromophoric dissolved organic matter (CDOM), elevated oil fluorescence emissions, and depletion of the carbon isotope composition (δ¹³C) of the seawater. The abundance of the picophytoplankton Synechococcus was not affected, but the proportion of low nucleic acid (LNA) bacteria was significantly higher. Moreover, specific bacterial genera (Alcanivorax, Salinisphaera, and Oleibacter) were enriched in the seawater microbiome. Metagenome-assembled genomes (MAGs) suggested that such bacteria presented pathways for growing on oil hydrocarbons. Traces of polycyclic aromatic hydrocarbons (PAHs) were also detected in zooplankton tissues, revealing the rapid entry of oil pollutants into the pelagic food web. Our study emphasizes the early signs of short-lived spills as an important aspect of the prediction of long-term impacts of marine oil spills.

Uptake of polycyclic aromatic hydrocarbons via high-energy water accommodated fraction (HEWAF) by beach hoppers (Amphipoda, Talitridae) using different sandy beach exposure pathways

Sandy beach ecosystems are highly dynamic coastal environments subject to a variety of anthropogenic pressures and impacts. Pollution from oil spills can damage beach ecosystems through the toxic effects of hydrocarbons on organisms and the disruptive nature of large-scale clean-up practices. On temperate sandy beaches, intertidal talitrid amphipods are primary consumers of macrophyte wrack subsidies and serve as prey for higher trophic level consumers, such as birds and fish. These integral organisms of the beach food web can be exposed to hydrocarbons by direct contact with oiled sand through burrowing and by the consumption of oiled wrack. We experimentally evaluated the primary polycyclic aromatic hydrocarbon (PAH) exposure pathway via high-energy water accommodated fraction (HEWAF) for a species of talitrid amphipod (Megalorchestia pugettensis). Our results indicated that tissue PAH concentrations in talitrids were six-fold higher in treatments that included oiled sand compared to those with only oiled kelp and the controls.

Severe ecological impacts caused by one of the worst orphan oil spills worldwide

Orphan oil spills pose a severe risk to ocean sustainability; however, they are understudied. We provide the first synthetic assessment of short-term ecological impacts of the most extensive oil spill in tropical oceans, which affected 2900 km of Brazil's coastline in 2019. Oil ingestion, changes in sex ratio and size of animals, morphological abnormalities of larvae and eggs, mutagenic, behavioral, and morphological alterations, contamination by polycyclic aromatic hydrocarbons, and mortality were detected. A decrease in species richness and abundance of oil-sensitive animals, an increase in opportunistic and oil-tolerant organisms, and simplification of communities was observed. The impacts were observed in sponges, corals, mollusks, crustaceans, polychaetes, echinoderms, turtles, birds, fish, and mammals. The majority of studies were conducted on bioindicator substrate-associated organisms, with 68.4% of the studies examining the benthos, 21.2% the nekton, and 10.4% the plankton. Moreover, most of the current short-term impacts assessment studies were focused on the species level (66.7%), with fewer studies on the community level (19%), and even fewer on oil-affected ecosystems (14.3%). Oil-related impacts were detected in five sensitive habitats, including blue-carbon ecosystems (e.g., mangroves and seagrass beds) and coastal reefs. These results call for the development of new ocean-basin observation systems for orphan spills. Finally, we discuss how these mysterious oil spills from unknown sources pose a risk to sustainable development goals and ocean-based actions to tackle global climate change.

Biomimetic cellulose-nanocrystalline-based composite membrane with high flux for efficient purification of oil-in-water emulsions

The massive discharge of oily wastewater and oil spills are causing serious pollution to water resources. It is urgent to require clean and efficient method of purifying oily emulsions. Although the separation membranes with selective wettability have been widely used in the efficient purification of oil/water emulsions. It is still very challenging to develop functional films that are environmentally friendly, fouling resistant, inexpensive, easy to prepare, easy to scale, and highly efficient. Cellulose nanocrystalline-based composite membranes (CCM) were prepared by surface-initiated atom transfer radical polymerization (SATRP) and vacuum self-assembly. The prepared CCM is superhydrophilic and superoleophobic underwater due to the hydrophilic nature of the modified cellulose-nanocrystalline and the micro-nano surface structure. The CCM shows high separation efficiency (> 99.9 %), high flux (16,692 L^-1·m^-2·h^-1·bar^-1) for surfactant-stabilized oil-in-water emulsions, good cycle stability and anti-fouling performance. This biomass-derived membrane is green, cheap, easy to manufacture, scalable, super-wettability, and durability, it promises to be an alternative to separation membranes in today's market.

Superelastic 3D Assembled Clay/Graphene Aerogels for Continuous Solar Desalination and Oil/Organic Solvent Absorption

Superelastic, arbitrary-shaped, and 3D assembled clay/graphene aerogels (CGAs) are fabricated using commercial foam as sacrificial skeleton. The CGAs possess superelasticity under compressive strain of 95% and compressive stress of 0.09-0.23 MPa. The use of clay as skeletal support significantly reduces the use of graphene by 50%. The hydrophobic CGAs show high solvent absorption capacity of 186-519 times its own weight. Moreover, both the compression and combustion methods can be adopted for reusing the CGAs. In particular, it is demonstrated a design of 3D assembled hydrophilic CGA equipped with salt collection system for continuous solar desalination. Due to energy recovery and brine transport management promoted by this design, the 3D assembled CGA system exhibits an extremely high evaporation rate of 4.11 kg m-2  h-1 and excellent salt-resistant property without salt precipitation even in 20 wt% brine for continuous 36 h illumination (1 kW m-2 ), which is the best reported result from the solar desalination devices. More importantly, salts can be collected conveniently by squeezing and drying the solution out of the salt collection system. The work provides new insights into the design of 3D assembled CGAs and advances their applications in continuous solar desalination and efficient oil/organic solvent adsorption.

Control of Antarctic phytoplankton community composition and standing stock by light availability

Southern Ocean phytoplankton are especially subjected to pronounced seasonal and interannual changes in light availability. Although previous studies have examined the role of light in these environments, very few combined pigment-based taxonomy with flow cytometry to better discriminate the light response of various phytoplankton groups. In particular the different populations within the diverse and important taxonomic group of diatoms require further investigation. Six incubation experiments (9–10 days) were performed during the main productive period with natural seawater collected at the Western Antarctic Peninsula. Standing stock of Phaeocystis spp. cells displayed relatively fast accumulation under all levels of light (low, medium, high; 4–7, 30–50 and 150–200 µmol quanta m−2 s−1), whilst the small- and larger-sized diatom populations (4.5 and 20 µm diameter) exhibited faster accumulation in medium and high light. In contrast, intermediate-sized diatoms (11.5 µm diameter) displayed fastest net growth under low light, subsequently dominating the phytoplankton community. Low light was a key factor limiting accumulation and peak phytoplankton biomass, except one incubation displaying relatively high accumulation rates under low light. The 3-week low-light period prior to experimentation likely allowed adaptation to maximize achievable growth and seems a strong determinant of whether the different natural Antarctic phytoplankton populations sustain, thrive or decline. Our study provides improved insight into how light intensity modulates the net response of key Antarctic phytoplankton, both between and within taxonomic groups.

Novel Magnetically Driven Superhydrophobic Sponges Coated with Asphaltene/Kaolin Nanoparticles for Effective Oil Spill Cleanup

Fast and effective cleanup of oil spills remains a global challenge. A modified commercial sponge with superhydrophobicity, strong absorption capacity, outstanding magnetic response, and fire resistance were fabricated by a facile and inexpensive route of dip-coated melamine sponge carbonization. The low-cost petroleum asphaltene and kaolin nanoparticles were used as the dip-coating reagent. High absorption capacity of the fabricated sponges allowed rapid and continuous removal of oil contaminants. Taking advantage of the good refractory property, the sponges can be used in burning conditions and directly reused after burning out of the absorbed oil. Reusability tests showed that the modified sponges still maintained high absorption capacity (>85%) after six regeneration and reuse cycles. These characteristics make the fabricated sponge a promising aid to promote effective in situ burning cleanup of oil spills, contributing as a magnetic oil collector and a fire-resistant flexible boom. An example usage scenario of the sponges applied to in situ burning cleanup of oil spills is described.

Electro-optic sampling based characterization of broad-band high efficiency THz-FEL

Extremely high beam-to-radiation energy conversion efficiencies can be obtained in a THz FEL using a strongly tapered helical undulator at the zero-slippage resonant condition, where a circular waveguide is used to match the radiation group velocity to the electron beam longitudinal velocity. In this paper we report on the first electro-optic sampling (EOS) based measurements of the broadband THz FEL radiation pulses emitted in this regime. The THz field waveforms are reconstructed in the spatial and temporal domains using multi-shot and single-shot EOS schemes respectively. The measurements are performed varying the input electron beam energy in the undulator providing insights on the complex dynamics in a waveguide FEL.

Transcriptome responses in copepods Calanus finmarchicus, Calanus glacialis and Calanus hyperboreus exposed to phenanthrene and benzo[a]pyrene

Arctic and sub-arctic pelagic organisms can be exposed to effluents and spills from offshore petroleum-related activities and thus it is important to understand how they respond to crude oil related contaminants such as polycyclic aromatic hydrocarbons (PAHs). The copepod species Calanus finmarchicus, Calanus glacialis and Calanus hyperboreus represent key links in the arctic marine food web. We performed a transcriptome analysis of the three species exposed to phenanthrene (Phe) and benzo[a]pyrene (BaP) representing low and high molecular weight PAHs, respectively. Differential expression of several genes involved in many cellular pathways was observed after 72 h exposure to Phe (0.1 μM) and BaP (0.1 μM). In C. finmarchicus and C. glacialis, the exposure resulted in up-regulation of genes encoding enzymes in xenobiotic biotransformation, particularly the phase II cytosolic sulfonation system that include 3'-phosphoadenosine 5'-phosphosulfate synthase (PAPSS) and sulfotransferases (SULTs). The sulfonation pathway genes were more strongly induced by BaP than Phe in C. finmarchicus and C. glacialis but were not affected in C. hyperboreus. However, a larger number of genes and pathways were modulated in C. hyperboreus by the PAHs including genes encoding xenobiotic biotransformation and lipid metabolism enzymes, suggesting stronger responses in this species. The results suggest that the cytosolic sulfonation is a major phase II conjugation pathway for PAHs in C. finmarchicus and C. glacialis. Some of the biotransformation systems affected are known to be involved in metabolism of endogenous compounds such as ecdysteroids, which may suggest potential interference with physiological and developmental processes of the copepod species.

Advancement in oil forensics through the addition of polycyclic aromatic sulfur heterocycles as biomarkers in diagnostic ratios

In current oil spill forensics, diagnostic ratios of hydrocarbon biomarker responses are commonly used to compare oil spill samples to source materials in order to determine the identity of the oil. This well recognized procedure was developed by the European Committee for Standardization (CEN) with corresponding published EN 15522-2 Oil Spill Identification guidelines. However, it is further recognized that weathering can have a negative effect on some of the biomarkers used in the analysis, leading to decreased confidence in the result. In this study, polycyclic aromatic sulfur heterocycles (PASHs) and their alkylated forms (APASHs) were assessed for their potential as additional biomarkers. With the aim of identifying stable PASHs and APASHs useful as weathered oil biomarkers, the superior specificity of gas chromatography with high resolution mass spectrometry was exploited to determine chromatographic peak responses for sixteen petroleum oil samples. Extensive study, involving microcosm extreme weathering and spreadsheet development, led to the identification of 19 new diagnostic ratios based on newly discovered stable PASH and APASH biomarkers. Application of the extended diagnostic ratio suite showed high potential to improve the forensic attribution of post-spill weathered oil back to its original source.

Chronic oiling in global oceans

Ocean oil slicks can be attributed to natural seepages or to anthropogenic discharges. To date, the global picture of their distribution and relative natural and anthropogenic contributions remains unclear. Here, by analyzing 563,705 Sentinel-1 images from 2014-2019, we provide the first global map of oil slicks and a detailed inventory of static-and-persistent sources (natural seeps, platforms, and pipelines). About 90% of oil slicks were within 160 kilometers of shorelines, with 21 high-density slick belts coinciding well with shipping routes. Quantified by slick area, the proportion of anthropogenic discharges was an order of magnitude greater than natural seepages (94 versus 6%), in contrast to the previous estimate quantified by volume during 1990-1999 (54 versus 46%). Our findings reveal that the present-day anthropogenic contribution to marine oil pollution may have been substantially underestimated.

Interactions between soil protists and pollutants: An unsolved puzzle

Soil protists are essential but often overlooked in soils, although they play crucial functional roles in the terrestrial ecosystem. While soil protists have drawn increased attention to their functional role in soils, their interaction with soil pollutants remains unresolved. This review provides a first overview of the current understanding of interactions between soil protists and major pollutants (heavy metals, organic pollutants, nanoparticles, and soil pathogens). We summarize how soil pollutants affect protists and vice versa, showing that we are just beginning to understand their complex interactions. In addition, we identify five research gaps, including hidden diversity, adaptive mechanisms, species interactions, soil bioindicators and environmental applications, and we hope that our review will help promote and build research guidelines for the future. In conclusion, a better understanding of soil pollutant-protist interactions will significantly increase our knowledge of the pollution ecology in the soil and how soil organisms respond and adapt to environmental pollution, which will contribute to the bioremediation and environmental applications of protists in soil.

Global Tracking of Transformation Products of Environmental Contaminants by 2H-Labeled Stable Isotope-Assisted Metabolomics

Stable isotope-assisted metabolomics (SIAM) enables global tracking of isotopic labels in nontargeted metabolomics in living organisms. However, its application in tracking transformation products (TPs, as metabolites of contaminants) of environmental contaminants is still a challenge due to limits in methodology, unmatured algorithms, and the high cost of ¹³C-labeled contaminants. Therefore, we developed a ²H-SIAM pipeline coupled with a highly flexible algorithm ²H-SIAM(1.0) (https://github.com/kechen1984/2H-SIAM), facilitating tracking TPs of contaminants in the environmental matrix. A detailed discussion illustrates the theory, behavior, and prospect of ²H-SIAM. We demonstrate that the proposed ²H-SIAM pipeline has unique advantages over ¹³C-SIAM, for example, cost-effective ²H-labeled contaminants, easy synthesis of ²H-labeled emerging contaminants, and providing more structural information. A pyrene soil degradation study further confirmed its high performance. It efficiently discarded 99% of noise signals and extracted 52 features from the nontargeted high resolution mass spectrometry (HRMS) data. Among them, 13 features were annotated as TPs of pyrene with identification confidence from Level 2a to Level 5, and 5 TPs were reported for the first time. In conclusion, the proposed ²H-SIAM pipeline is powerful in tracking potential TPs of environmental contaminants with unique advantages.

Fate of polycyclic aromatic compounds from diluted bitumen spilled into freshwater limnocorrals

Diluted bitumens (dilbits) are produced by mixing highly viscous bitumen with lighter petroleum products to facilitate transport. The unique physical and chemical properties of dilbit may affect the environmental fate and effects of dilbit-derived chemical compounds when spilled. To further explore this, we monitored experimental spills of Cold Lake Winter Blend (CLWB) dilbit for 70 days in limnocorrals installed in a freshwater boreal lake. A regression design with 2 controls and 7 treatments was used to assess the fate and behaviour of polycyclic aromatic compounds (PACs) as they partitioned from the dilbit into the air, water column and sediments. Treatments ranged from 1.5 to 180 L of CLWB, resulting in oil:water ratios ranging between 1:71000 to 1:500 (v:v). We began to detect elevated concentrations of PACs as early as 6 h post-addition in the air, 12 h post-addition in the water column, and 15-28 d post-addition in the sediments. By the end of the experiment, concentrations of PACs had largely declined in the water column but remained elevated in the sediments. Our results demonstrate that under conditions typical of temperate boreal lakes, only a small proportion of PACs from dilbit enters the aquatic system, but even so, may produce concentrations of ecotoxicological concern, especially in the sediments, which is the ultimate sink for dilbit-derived PACs.

Sustainable Cross-Linkers for the Synthesis of Cellulose-Based Aerogels: Research and Application

Cellulose aerogels with polyester resin as cross-linkers have attracted much attention. This study describes the route to produce a fully bio-based aerogel with high added value from waste paper and starch, cellulose acetate and starch–cellulose acetate mixture as cross-linkers for oil adsorption, instead of the environmentally harmful polyester resin. The manufacturing process is simple, sustainable and cost-efficient, without releasing harmful by-products into the environment. The effects of different cross-linkers on the oil adsorption, dynamic oil retention, reusability and morphology of the aerogels were studied in detail. Experimental results show that these environmentally friendly recycled aerogels have a very low density, i.e., —0.0110–0.0209 g cm−3, and highly porous structures, with a porosity of 96.74–99.18%. The synthesized hydrophobic aerogels showed contact angles of ∼124–129°. The compression moduli are lower than that of an aerogel with polyester as a cross-linker, but the compression modulus of the mixture of starch and cellulose acetate especially shows a higher value than expected. The sorption capacity of the aerogels with bio-based cross-linkers was significantly increased compared to the aerogels with polyester; it is now up to 56 times their own weight. The aerogels also have good oil-retention properties.

Dissecting the Chain Length Effect on Separation of Alkane-in-Water Emulsions with Superwetting Microchannels

Oil/water separation is an essential process in the petrochemical industry, environmental remediation, and water treatment. Alkanes are the major components of crude oil and are difficult to separate once they form emulsions in water. Much less attention has been focused on the feature of liquid alkanes that could, in turn, influence the separation process. The role of chain length is systematically studied herein by separating the alkane-in-water emulsions with superwetting titanium microchannels of 14-55 μm. The chain length covers the entire liquid alkane spectrum with carbon numbers ranging from 6 to 16. The separation efficiency decreases while the TOC content increases with the chain length of liquid alkanes for a given channel. This is attributed to the small Ostwald ripening rate with the long chains, which stabilize the oil droplets of small sizes that could pass through the zigzag channels. Accordingly, a high separation efficiency of >99.97% and a low TOC content of <5 ppm are achieved with superhydrophilic channels of 14 μm for alkanes with less than 12 carbons. The metallic microchannels surpass the conventional organic membranes and inorganic frameworks over the entire liquid n-alkane spectrum, paving the way for the future development of oil/water separation using porous metals.

Solvent-free processing of eco-friendly magnetic and superhydrophobic absorbent from all-plant-based materials for efficient oil and organic solvent sorption

The unique features of bioresources such as cellulose and bio-wax include renewability, biodegradability, low cost, and abundance on Earth. Therefore, their efficient use is essential for a sustainable economy. Herein, we report a facile method for the surface modification of pretreated cotton with a bio-wax emulsion in water and Fe₃O₄ nanoparticles to fabricate a green, durable, magnetic, and superhydrophobic/superoleophilic absorbent for the sorption of oil and organic solvents. Magnetic superhydrophobic cotton (MSC) was successfully prepared via a simple two-step dip-coating method without using any toxic organic reagents. The as-prepared MSC was used to selectively absorb various types of oils and organic solvents up to approximately 20-50 times its own weight. Furthermore, it exhibited a stable magnetic responsivity and high reusability in oil/water separation cycles. In addition, the removal and collection of the absorbed oil/organic solvents were easily achieved with distillation and a vacuum air pump. Moreover, the as-prepared MSC was used in a heavy oil/water gravity-separation filter system and in the continuous collection of a light oil from water surfaces using a pump. The proposed concept may provide a green and sustainable strategy for fabricating superhydrophobic/superoleophilic materials for efficient sorption of oils and organic solvents.

Effect of Oil Properties on the Generation of Nano-Aerosols During Bubble Bursting Through Crude Oil-Dispersant Slicks

This study examines the effect of dispersant and oil properties on the aerosolization of fresh and weathered surface crude oil slicks by bursting of a plume of ∼0.7 mm bubbles. A scanning mobility particle sizer measures the size distribution of aerosols in the 20-400 nm range in a clean air chamber. The 500-μm-thick slicks contain oils with varying origin, viscosity, interfacial tension, and weathering state. Test are performed with and without premixed dispersant (Corexit 9500A), which reduces the oil-seawater interfacial tension by 2 orders of magnitude at a dispersant-to-oil ratio (DOR) of 1:25. When compared to aerosolization in clean seawater, the nano-aerosol concentration decreases for slicks without dispersant but increases by 27%-351% upon introduction of dispersant. For most cases, the airborne nanodroplet concentration increases with decreasing Capillary or Morton numbers as well as the ratio of the so-called inner to thermal length scales. To explain the airborne nanodroplet generation in an oil-dispersant mixture, we show that prior to bubble injection, even minimal agitation of the interface causes generation of a subsurface cloud of nanodroplets that diffuses away from the interface. This process appears to be caused by thermal capillary instability when the interfacial tension is low enough to increase the thermal length scale to a few nanometers.

Cellular accumulation of crude oil compounds reduces the competitive fitness of the coral symbiont Symbiodinium glynnii

Oil spill events in the marine environment can have a deleterious impact on the affected ecosystems, such as coral reefs, with direct consequences for their socioeconomic value. The mutualistic relationship between tropical corals and their dinoflagellate symbionts (Symbiodiniaceae) provide structural and nutritional basis for a high local biodiversity in oligotrophic waters. Here, we investigated effects of crude oil water-accommodated fraction on the competitive fitness of the model zooxanthellae species Symbiodinium glynnii. Results of laboratory essays demonstrate that crude oil carbon is incorporated into the cellular biomass with a concomitant change of δ¹³C isotopic value. Carcinogenic/mutagenic polycyclic aromatic hydrocarbons were identified in the culture media and were responsible for a linear reduction in population growth of S. glynnii, presumably related to energy relocation for DNA repair. Additionally, the experiments revealed that physiological effects induced by crude oil compounds are genetically inherited by the following generations under non-contaminated growth conditions, and induce a reduction in the competitive fitness to cope with other environmental parameters, such as low salinity. We suggest that the effects of crude oil contamination represent an imparing factor for S. glynnii coping with anthropogenic drivers (e.g. warming and acidification) and interfere with the delicate symbiont-host relationship of tropical corals. This is especially relevant in the coastal areas of northeastern Brazil where an oil spill event deposited crude oil on shallow water sediments with the potential to be resuspended to the water column by physical and/or biological activity, enhancing the risk of future coral bleaching events.

Rapid and Scalable Synthesis of a Vanillin-Based Organogelator and Its Durable Composite for a Comprehensive Remediation of Crude-Oil Spillages

Phase-selective organogelators (PSOGs) that have immense potential in effective oil/water separation, antifouling coating, ice-repellent coating, and so on are often synthesized by following complex and multistep synthesis procedures that involve additional and tedious purification steps. On the other side, a comprehensive, selective, environmentally friendly, and energy-efficient separation of different and complex forms of oil spillages (e.g., floating oil or oil-in-water emulsions) from contaminated aqueous phase is challenging to achieve based on earlier-reported PSOGs and their composites. Here, vanillin, a naturally abundant molecule, is unprecedentedly exploited to synthesize a purified PSOG (with a yield of 97%) by adopting a catalyst-free, single-step, and rapid (<2 min) synthesis process under ambient conditions. The Schiff's base reaction between the aldehyde group of vanillin and the primary amine group of octadecylamine provided the desired and purified PSOG-without demanding any additional purification processes (e.g., column chromatography). The appropriate coexistence of the imine linkage, hydrocarbon tail, and hydroxyl group in the vanillin-derived organogelator (VDOG) played an important role in achieving a self-standing organogel that sustained ∼60 times the external load of its weight-without having any noticeable physical deformation. Further, an appropriate and facile integration of the synthesized VDOG with a commercially available biodegradable porous and spongy matrix (i.e., polyurethane sponge) allowed us to develop an oil-selective absorbent with (1) enhanced water repellency (140°) and (2) superior oil-absorption capacity (i.e., 55.2 times its own weight). Such composite material remained durable for repetitive (at least for 50 cycles) and distillation-free separation/recovery of crude oil at practically relevant severe and diverse settings. Thereafter, the synthesized VDOG was successfully and unprecedentedly extended to demonstrate rapid, facile, and efficient separation of surfactant-stabilized oil-in-water emulsions.

Deep remediation of oil spill based on the dispersion and photocatalytic degradation of biosurfactant-modified TiO2

The employment of dispersant was an effective method to treat marine oil spill pollution. However, conventional dispersants only showed a single oil dispersion. Here, by modifying TiO₂ nanoparticles with biosurfactant-Rhamnolipids (Rha), a highly efficient particulate dispersant with photocatalytic activity was developed. Rha-TiO₂ showed both excellent oil spill dispersion and facilitated photodegradation for oil simultaneously. The oil droplets dispersed by Rha-TiO₂ in seawater exhibited long time stability, which indicated the synergistic emulsification interactions between TiO₂ and Rha in artificial sea water (ASW). The dispersion mechanism of Rha-TiO₂ was analyzed, we found the TiO₂ nanoparticles alone weren't effectively emulsified oil in high salinity ASW, but the addition of a small amount of Rha could modify the surface wettability of TiO₂ nanoparticles to form the stable emulsion. In addition, the addition of a small amount of Rha could reduce the surface tension of the oil-water interface, which contribute to increasing the content of TiO₂ nanoparticles at the oil-water interface, form a steric rigid layer around the oil droplets to prevent droplet coalescence and facilitate the further photocatalytic degradation of oil. In short, the Rha-TiO₂ nanoparticles could effective disperse oil in ASW, meanwhile the TiO₂ also played the role of photocatalytic degradation of oil pollution. Hence, this study developed a novel photocatalytic particulate dispersant to remediate marine oil spill and delivered a new feasible solution for practical oil spill treatment in the future.

An Assessment of Marine Ecosystem Damage from the Penglai 19-3 Oil Spill Accident

Oil spills have immediate adverse effects on marine ecological functions. Accurate assessment of the damage caused by the oil spill is of great significance for the protection of marine ecosystems. In this study the observation data of Chaetoceros and shellfish before and after the Penglai 19-3 oil spill in the Bohai Sea were analyzed by the least-squares fitting method and radial basis function (RBF) interpolation. Besides, an oil transport model is provided which considers both the hydrodynamic mechanism and monitoring data to accurately simulate the spatial and temporal distribution of total petroleum hydrocarbons (TPH) in the Bohai Sea. It was found that the abundance of Chaetoceros and shellfish exposed to the oil spill decreased rapidly. The biomass loss of Chaetoceros and shellfish are 7.25×1014~7.28×1014 ind and 2.30×1012~2.51×1012 ind in the area with TPH over 50 mg/m3 during the observation period, respectively. This study highlights the evaluation of ecological resource loss caused by the oil spill, which is useful for the protection and restoration of the biological resources following the oil spill.

Statistical Optimisation of Diesel Biodegradation at Low Temperatures by an Antarctic Marine Bacterial Consortium Isolated from Non-Contaminated Seawater

Hydrocarbon pollution is widespread around the globe and, even in the remoteness of Antarctica, the impacts of hydrocarbons from anthropogenic sources are still apparent. Antarctica’s chronically cold temperatures and other extreme environmental conditions reduce the rates of biological processes, including the biodegradation of pollutants. However, the native Antarctic microbial diversity provides a reservoir of cold-adapted microorganisms, some of which have the potential for biodegradation. This study evaluated the diesel hydrocarbon-degrading ability of a psychrotolerant marine bacterial consortium obtained from the coast of the north-west Antarctic Peninsula. The consortium’s growth conditions were optimised using one-factor-at-a-time (OFAT) and statistical response surface methodology (RSM), which identified optimal growth conditions of pH 8.0, 10 °C, 25 ppt NaCl and 1.5 g/L NH₄NO₃. The predicted model was highly significant and confirmed that the parameters’ salinity, temperature, nitrogen concentration and initial diesel concentration significantly influenced diesel biodegradation. Using the optimised values generated by RSM, a mass reduction of 12.23 mg/mL from the initial 30.518 mg/mL (4% (w/v)) concentration of diesel was achieved within a 6 d incubation period. This study provides further evidence for the presence of native hydrocarbon-degrading bacteria in non-contaminated Antarctic seawater.

Distinct microbial community along the chronic oil pollution continuum of the Persian Gulf converge with oil spill accidents

The Persian Gulf, hosting ca. 48% of the world's oil reserves, has been chronically exposed to natural oil seepage. Oil spill studies show a shift in microbial community composition in response to oil pollution; however, the influence of chronic oil exposure on the microbial community remains unknown. We performed genome-resolved comparative analyses of the water and sediment samples along Persian Gulf's pollution continuum (Strait of Hormuz, Asalouyeh, and Khark Island). Continuous exposure to trace amounts of pollution primed the intrinsic and rare marine oil-degrading microbes such as Oceanospirillales, Flavobacteriales, Alteromonadales, and Rhodobacterales to bloom in response to oil pollution in Asalouyeh and Khark samples. Comparative analysis of the Persian Gulf samples with 106 oil-polluted marine samples reveals that the hydrocarbon type, exposure time, and sediment depth are the main determinants of microbial response to pollution. High aliphatic content of the pollution enriched for Oceanospirillales, Alteromonadales, and Pseudomonadales whereas, Alteromonadales, Cellvibrionales, Flavobacteriales, and Rhodobacterales dominate polyaromatic polluted samples. In chronic exposure and oil spill events, the community composition converges towards higher dominance of oil-degrading constituents while promoting the division of labor for successful bioremediation.

Tracking and Assessing Oil Spill Toxicity to Aquatic Organisms: A Novel Approach

An in situ exposure and effects bioassay system was developed for assessing the toxicity of oil spills to aquatic organisms. The assessment tool combines components of 2 previously developed systems, the sediment ecotoxicity assessment ring (SEA Ring) and the drifting particle simulator. The integrated drifting exposure and effects assessment ring (DEEAR) is comprised of a Global Positioning System (GPS) float, a drifter drogue, the SEA Ring, and the Cyclops-7 fluorescent sensor. Polyethylene passive sampling devices (PED) were mounted for an additional means to characterize water quality conditions and exposures. The DEEAR is optimized for evaluating oil exposure and toxicity in the shallow surface mixing layer of marine waters. A short-term preliminary test was conducted in San Diego, California, USA, to verify the operation of the GPS tracking, the iridium communications, and the integrated SEA Ring exposure system. Further, a proof-of-concept demonstration was conducted offshore in the Santa Barbara Channel, where natural oil seeps produce surface slicks and sheens. Two DEEAR units were deployed for 24 h-one within the oil slick and one in an area outside observable slicks. An aerial drone provided tracking of the surface oil and optimal sites for deployment. The DEEAR proof-of-concept demonstrated integrated real-time tracking and characterization of oil exposures by grab samples, PED, and fluorescent sensors. Oil exposures were directly linked to toxic responses in fish and mysids. This novel integrated system shows promise for use in a variety of aquatic sites to more accurately determine in situ oil exposure and toxicity. Environ Toxicol Chem 2021;40:1452-1462. © 2021 SETAC.

Miniaturised marine tests as indicators of aromatic hydrocarbon toxicity: Potential applicability to oil spill assessment

Assessing oil spill toxicity in real time is challenging due to dynamic field exposures and lack of simple, rapid, and sensitive tests. We investigated the relative sensitivity of two commercially available marine toxicity tests to aromatic hydrocarbons using the target lipid model (TLM). State of the art passive dosing in sealed vials was used to assess the sensitivity of brine shrimp (Artemia franciscana) and rotifer (Brachionus plicatilis). Organisms were exposed to toluene, 1-methylnaphthalene and phenanthrene for 24 h. Toxicity results were analysed using the TLM to estimate the critical target lipid body burden and support comparison to empirical data for 79 other aquatic organisms. Our findings demonstrate the applicability of passive dosing to test small volumes and indicate that the two rapid cyst-based assays are insensitive in detecting hydrocarbon exposures compared to other aquatic species. Our results highlight the limitations of applying these tests for oil pollution monitoring and decision-making.

Solid inoculants as a practice for bioaugmentation to enhance bioremediation of hydrocarbon contaminated areas

Vacuum freeze-drying is a scientifically advanced method to prepare solid inoculants from oil degrading bacterium. The introduction of oil-degrading microbes or bioaugmentation can be an efficient way to bioremediate oil spills in marine areas, where oil-degrading bacteria are deficient. The purpose of this study is to evaluate the potential use of solid inoculants of LZ-2 bacteria to enhance the degradation rate of crude oil. In this study, response surface methodology (RSM) was incorporated into the experimental design to optimize a response, which is influenced by different protectants. Our results showed that five factors have interactive and synergistic protective effects on the growth of LZ-2. Optimal growth of freeze-dried LZ-2 (63.8%) was observed with a 10.5% solution of skim milk supplemented with 14.3% sucrose, 14.4% of trehalose, 4.9% of glycerin and 14.7% of β-cyclodextrin. The culture grew in medium containing crude oil (3 g L^-1) at 37 °C at 150 rpm for 30 d, GC and GC-MS analysis showed biodegradation of 44.2 and 21.6% for total saturate and aromatic hydrocarbons respectively. These results indicated that the solid inoculants of LZ-2 bacteria had the potential to be used for ex-situ bioremediation of hydrocarbon pollutants associated with crude oil.

Carbon Nanotubes-Filled Siloxane Composite Foams for Oil Recovery Application: Compression Properties

This paper studies the correlation between oil recovery usability and mechanical behavior under compression loads of an innovative oil recovery material. The examined composites are silicone foams filled with carbon nanotubes (CNT). Here, the reutilization of oil recovery processes of the newly developed composite foams is evaluated. In this regard, static and cyclic compressive tests are carried out. Samples filled with pristine and functionalized CNT are tested to evaluate the influence of the filler’s characteristics on the composite foam’s mechanical behavior. The results show that the presence of CNT (CNT-0) increases the elastic modulus (0.030 MPa) and collapse stress (0.010 MPa) of the siloxane matrix. On the contrary, as the CNT functionalization degree increases, a worsening of the composite’s mechanical performance is observed. CNT-0 foam evidences, also, the optimal mechanical stability to cyclic compressive loads, maintaining high stress values until 30 cycles. Furthermore, a correlation between the absorption capacity, elastic modulus, and cyclability is reported, highlighting a simplified approach to tailor the high absorption durability performance of filled CNT silicone foams. The promising results confirm the possible reuse of these new composite foams as absorbent materials for oil spill recovery applications.

Omni-Directional Protected Nanofiber Membranes by Surface Segregation of PDMS-Terminated Triblock Copolymer for High-Efficiency Oil/Water Emulsion Separation

An excellent antifouling membrane with high permeate flux is required for oil/water emulsion separation due to ever-increasing oily industrial wastewater. Thus, an intriguing integration of the Omni-directional protected porous membrane that combines a high porosity nanofiber membrane with a surface segregation mechanism is established for the first time. By applying polydimethylsiloxane(PDMS)-terminated triblock copolymer, the enrichment of the hydrophilic poly(ethylene oxide) (PEO) segment and the nonpolar PDMS segment on the surface of the nanofiber endowed the nanofiber membrane with underwater oleophobicity and low oil adhesion force, exhibiting oil resistance as well as oil release property. An ultrahigh permeate flux of ∼7115 L m^-2 h^-1 with a separation efficiency of ∼97.88% is achieved under the driving force of gravity (∼0.9 kPa), which is the highest permeate flux ever reported under similar conditions. Moreover, the surface segregation nanofiber membrane shows excellent reusability and ultrahigh permeate flux with the assistance of stirring in a long-term test, revealing the promising performances for the further particular application of oily wastewater.

Current issues confounding the rapid toxicological assessment of oil spills

Oil spills of varying magnitude occur every year, each presenting a unique challenge to the local ecosystem. The complex, changeable nature of oil makes standardised risk assessment difficult. Our review of the state of science regarding oil's unique complexity; biological impact of oil spills and use of rapid assessment tools, including commercial toxicity kits and bioassays, allows us to explore the current issues preventing effective, rapid risk assessment of oils. We found that despite the advantages to monitoring programmes of using well validated standardised tests, which investigate impacts across trophic levels at environmentally relevant concentrations, only a small percentage of the available tests are specialised for use within the marine environment, or validated for the assessment of crude oil toxicity. We discuss the use of rapid tests at low trophic levels in addition to relevant sublethal toxicity assays to allow the characterisation of oil, dispersant and oil and dispersant mixture toxicity. We identify novel, passive dosing techniques as a practical and reproducible means of improving the accuracy and maintenance of nominal concentrations. Future work should explore the possibility of linking this tiered testing system with ecosystem models to allow the prediction and risk assessment of the entire ecosystem.

Invisible oil beyond the Deepwater Horizon satellite footprint

Major oil spills are catastrophic events that immensely affect the environment and society, yet determining their spatial extent is a highly complex task. During the Deepwater Horizon (DWH) blowout, ~149,000 km² of the Gulf of Mexico (GoM) was covered by oil slicks and vast areas of the Gulf were closed for fishing. Yet, the satellite footprint does not necessarily capture the entire oil spill extent. Here, we use in situ observations and oil spill transport modeling to examine the full extent of the DWH spill, focusing on toxic-to-biota (i.e., marine organisms) oil concentration ranges. We demonstrate that large areas of the GoM were exposed to invisible and toxic oil that extended beyond the boundaries of the satellite footprint and the fishery closures. With a global increase in petroleum production-related activities, a careful assessment of oil spills' full extent is necessary to maximize environmental and public safety.

Synthesis of Dual-Functional and Robust Underwater Superoleophobic Interfaces

Fish-scale-mimicked super oil-repelling wettability that functions under water has emerged as an important avenue for developing various functional materials. Mainly, polymeric hydrogel, brittle metal oxides, and electrostatic multilayers have been utilized for synthesizing an artificial underwater superoleophobic interface, and most of these reported artificial bioinspired wettabilities are likely to be compromised under practically relevant severe settings. Moreover, a design of a dual-functional fish-scale-mimicked interface that would be capable of separating water-soluble organic pollutants, in addition to the eco-friendly removal of different forms of contaminated oils under severe settings, could be highly useful in addressing globally recognized severe water pollution problems. In this report, a dual-functional underwater superoleophobic membrane is introduced for simultaneous removal of  contaminated dyes and oil/oily phase, where graphene oxide (GO) nanosheets were strategically integrated with naturally abundant and environmentally friendly cotton fibers by adopting mussel-inspired chemistry. The synthesized membrane was found to exhibit fish-scale-mimicked nonadhesive underwater superoleophobicity, and this super oil repellency remained unaffected even after prolonged exposures to various practically relevant harsh chemical and physical conditions. Moreover, this material was capable of rapid (within 2 min) adsorption of water-soluble cationic organic dyes with high adsorption capacity (136 mg/g for methylene blue), following linear pseudo-second-order kinetics. The biomimicked extreme oil repellency was exploited for separating different forms (bulk and emulsion) of oil/oily (both sedimenting and floating) contaminants with high separation efficiency (above 98%), and the immobilized GO in the biomimicked membrane parallely allowed cationic organic dyes (methylene blue and crystal violet) to be removed from the aqueous phase through a single-step gravity-driven filtration process. The performance of simultaneous removal of cationic dyes and oil/oily contaminants remained unaffected even under various practically relevant severe settings including extremes of pH, sea water, river water, and so forth. Furthermore, the dual-functional biomimicked membrane was repetitively (10 times) used for successful separation of both the contaminated cationic dye and oil/oily phase from the aqueous phase, without affecting the separation efficiency. This simple approach is likely to provide a facile basis for addressing the problem of water pollution under practically relevant diverse and severe settings.