MV Wakashio grounding incident in Mauritius 2020: The world's first major spillage of Very Low Sulfur Fuel Oil

Comprehensive characterization of sulfur compounds in the diesel fraction using methylation/demethylation derived separation and GC × GC-MS/FID analysis

Comprehensive characterization of petroleum-derived sulfur compounds is crucial for researching and developing desulfurization catalysts, equipment, and processes. However, the complex composition and low concentration of sulfur compounds in oils make it challenging for molecular-level separation and characterization. In this work, sulfur compounds in the straight-run diesel fraction were selectively separated from the oil by the methylation/demethylation method, effectively yielding high-purity thiophenes and sulfides. Molecular-level compositional and structural characterization of sulfur compounds was accomplished through comprehensive two-dimensional gas chromatography (GC × GC) coupled with time-of-flight mass spectrometry. The separation significantly enhances the detection sensitivity for low-content sulfur compounds, thereby enabling a more comprehensive characterization of their molecular compositions and structures. Sulfur compounds with diverse skeletons and carbon numbers were tentatively characterized, including 1~3 cyclic sulfides, thiophenes, benzothiophenes, dihydrobenzothiophenes, dibenzothiophenes, tetrahydrodibenzothiophenes, phenanthrothiophenes, and benzonaphthothiophenes. Additionally, hundreds of individual sulfur compounds were characterized by mass spectrometry. Quantitative analysis for individual compounds and compound types was conducted using a flame ionization detector.

Macropore absorbent with bihydrophilic layers for the recovery of low-sulfur fuel oil

Conventional absorbent pads are widely employed for oil spill cleanup; however, their microporous structures face challenges in absorbing low-sulfur fuel oil (LSFO), especially at lower temperatures when LSFO solidifies owing to its high-viscosity shear stress. In this study, we developed a macroporous absorbent with bihydrophilic layers (MABL), i.e., a central hydrophobic layer sandwiched between two hydrophilic layers, with improved LSFO absorption efficiency. Unlike conventional hydrophobic absorbents, which remain predominantly afloat on the water surface with minimal submersion, the MABL achieves partial submersion owing to the wettability contrast of the bottom and central hydrophobic layers. This configuration ensures that the water surface aligns within the thickness range of MABL. The optimal pore size for LSFO absorption is determined to be 2.8 mm; pores smaller than 2.8 mm hinder LSFO absorption because of high-viscosity shear stress, while larger pores result in easy release of the absorbed LSFO. Notably, as the temperature decreases and LSFO solidifies, the MABL with 2.8-mm pores demonstrates significantly higher LSFO absorption capacity than conventional absorbent pads. Furthermore, a retention capability experiment reveals that the MABL with a pore size of 2.8 mm retains absorbed LSFO effectively under rotational flow in water and high-acceleration vibration in air, demonstrating its stability under dynamic conditions.

Hierarchically-structured ratchet skimmer with superhydrophilicity for continuous recovery of high-viscosity oil

Oil spill accidents have series environmental and economic impacts, increasing the demand for efficient technologies to recover oil from contaminated waters. In this study, a hierarchically structured ratchet surface with superhydrophilicity was presented as a novel oil skimming mechanism for the recovery of high-viscosity oil, particularly low-sulfur fuel oil (LSFO), which has recently been used as marine fuel in open water environments. The interaction between the superhydrophilic ratchet and oil provides favorable conditions for oil retention at the water surface. The hierarchical structure minimizes contact between oil and the skimmer surface, allowing separation without a scraper, even at higher speeds. In addition, the ratchet skimmer generates a water surface flow near the skimmer, driving oil to the drum and improving skimming performance. The skimmer achieved a recovery efficiency of almost 100 % under various experimental conditions with an LSFO viscosity of up to 12,000 cSt.

Stranded heavy fuel oil exposure causes deformities, cardiac dysfunction, and oxidative stress in marine medaka Oryzias melastigma using an oiled-gravel-column system

Heavy fuel oil (HFO) stranded on the coastline poses a potential threat to the health of marine fish after an oil spill. In this study, an oiled-gravel-column (OGC) system was established to investigate the toxic effects of stranded HFO on marine medaka Oryzias melastigma. HFO 380# (sulfur content 2.9%) was chosen as one type of high sulfur fuel oil for acute toxicity tests. The marine medaka larvae were exposed to the OGC system effluents with oil loading rates of 0 (control), 400, 800, 1600, and 3200 µg HFO/g gravel for 144 h, respectively. Results showed that a prevalence of blue sac disease signs presented teratogenic effects, including decreased circulation, ventricular stretch, cardiac hemorrhage, and pericardial edema. Moreover, the treatments (800, 1600, and 3200 µg oil/g gravel) induced severe cardiotoxicity, characterized by significant bradycardia and reduced stroke volume with an overt decrease in cardiac output. Additionally, the antioxidant enzyme activities, including catalase (CAT), peroxidase (POD), and glutathione S-transferase (GST) were significantly upregulated at 800-3200 µg oil/g gravel except for a marked inhibition of CAT activity at 3200 µg oil/g gravel. Furthermore, significantly elevated protein carbonyl (PCO) levels were detected, suggesting that the organisms suffered severe protein oxidative damage subjected to the exposure. Overall, stranded HFO 380# exposure activated the antioxidant defense system (up-regulated POD and GST activities) of marine medaka and disrupted CAT activity, which could result in an oxidative stress state (elevated PCO levels) and might further contribute to cardiac dysfunction, deformities, and mortality.

Very low sulfur fuel oil spilled from the MV Wakashio in 2020 remains in sediments in a Mauritius mangrove ecosystem nearly three years after the grounding

The oil spill resulting from the grounding of the MV Wakashio on a reef off the coast of Mauritius in July 2020 was the world's first major spillage of Very Low Sulfur Fuel Oil (VLSFO) since the implementation of a Global Sulfur Cap from January 2020. In this study, we examine sediments collected in March 2023 from two Mauritius mangrove systems. Analyses by both gas chromatography-mass spectrometry and comprehensive two-dimensional gas chromatography confirmed, by comparison of molecular biomarkers, the presence of Wakashio VLSFO in one of the mangrove systems. The spilled oil had undergone extensive weathering resulting in substantial losses of toxic mono- and polycyclic aromatic compounds. Applying WebGNOME-ADIOS oil spill models to compare the fate of Wakashio VLSFO with traditional fuels suggests that more of the VLSFO would evaporate, naturally disperse, and undergo sedimentation compared to traditional fuels that were more likely to remain floating.

Forecasting Photo-Dissolution for Future Oil Spills at Sea: Effects of Oil Properties and Composition

Photo-dissolution, the photochemical production of water-soluble species from oil, can transfer oil-derived dissolved organic carbon (DOC) from floating surface slicks to the underlying seawater. Photo-dissolution was likely a quantitatively relevant fate process for the Macondo crude oil spilled during the 2010 Deepwater Horizon spill, but the importance of photo-dissolution for other oils is poorly constrained. This study evaluated the photo-dissolution reactivities (apparent quantum yields) and modeled rates for oils with diverse physical properties and chemical compositions, including an ultra low sulfur fuel oil (ULSFO). Photo-dissolution from UV (310 nm) light was strongly positively correlated with the fraction of small, gas-oil range compounds ( Collapse

Key Words

• DOC
• ULSFO
• dissolved organic carbon
• oil spills
• petroleum
• photo-dissolution
• photo-oxidation
• photochemistry
• ultra low sulfur fuel oil
• weathering

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MESH Headings Collapse

Grants

• Woods Hole Oceanographic Institution
• Great Lakes Oil Spill Center of Expertise
• Fisheries and Oceans Canada
• National Science Foundation Graduate Research Fellowship Program

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Affiliation(s)

Danielle Haas Freeman MIT-WHOI Joint Program in Oceanography/Applied Ocean Science & Engineering, Woods Hole, Massachusetts 02543, United States Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, United States
Robert K. Nelson Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, United States
Kali Pate Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, United States
Christopher M. Reddy Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, United States
Collin P. Ward Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, United States

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Collaborators Collapse

Geochemistry and the optics of geospatial analysis as a preposition of water quality on a macroscale

The water treatment depends exclusively on the identification of residues containing toxic chemical elements accumulated in NPs (nanoparticles), and ultrafine particles sourced from waste piles located at old, abandoned sulfuric acid factories containing phosphogypsum requires global attention. The general objective of this study is to quantify and analyze the hazardous chemical elements present in the leachate of waste from deactivated sulfuric acid factories, coupled in NPs and ultrafine particles, in the port region of the city of Imbituba, Santa Catarina, Brazil. Samples were collected in 2020, 2021, and 2022. Corresponding images from the Sentinel-3B OLCI satellite, taken in the same general vicinity, detected the levels of absorption coefficient of Detritus and Gelbstoff (ADG443_NN) in 443 m-1, chlorophyll-a (CHL_NN (m-3)), and total suspended matter (TSM_NN (g m-3) at 72 points on the marine coast of the port region. The results of inductively coupled plasma atomic-emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS) demonstrate that the leaching occurring in waste piles at the port area of Imbituba was the likely source of hazardous chemical elements (e.g., Mg, Sr, Nd, and Pr) in the environment. These leachates were formed due to the presence of coal pyrite and Fe-acid sulfates in said waste piles. The mobility of hazardous chemical elements potentiates changes in the marine ecosystem, in relation to ADG443_NN (m-1), CHL_NN (m-3), and TSM NN (g m-3), with values greater than 20 g m-3 found in 2021 and 2022. This indicated changes in the natural conditions of the marine ecosystem up to 30 km from the coast in the Atlantic Ocean, justifying public initiatives for water treatment on a global scale.

A framework for risk matrix design: A case of MASS navigation risk

Risk matrix, a tool for visualizing risk assessment results, is essential to facilitate the risk communication and risk management in risk-based decision-making processes related to new and unexplored socio-technical systems. The use of an appropriate risk matrix is discussed in the literature, but it is overlooked for emerging technologies such as Maritime Autonomous Surface Ships (MASS). In this study, a comprehensive framework for developing a risk matrix based on fuzzy Analytic Hierarchy Process (AHP) is proposed. In this framework, a linear function is defined where the risk index is treated as a response variable, while the probability and consequence indices are explanatory variables, with weights of these two indices representing their importance on given risk level. This significance is assessed by experts and quantified using AHP in interval type 2 fuzzy environment. A continuous risk diagram is then created and converted into a risk matrix that can be improved. To verify the feasibility of the proposed framework, a risk matrix is designed in the context of MASS grounding. The results show that the proposed approach is feasible. Our discussion results can provide new insights for the design of risk matrices and promote the management of MASS navigational risks.

Prediction of the marine spreading of low sulfur fuel oil using the long short-term memory model trained with three-phase numerical simulations

In this study, we focus on the development and validation of a deep learning (long short-term memory, LSTM)-based algorithm to predict the accidental spreading of LSFO (low sulfur fuel oil) on the water surface. The data for the training was obtained by numerical simulations of artificial geometries with different configurations of islands and shorelines and wind speeds (2.0-8.0 m/s). For simulating the spread of oils in O(102) km scales, the volume of fluid and discrete phase models were adopted, and the kinematic variables of particle location, particle velocity, and water velocity were collected as input features for LSTM model. The predicted spreading pattern of LSFO matched well with the simulation (less than 10 % in terms of the mean absolute error for the untrained data). Finally, we applied the model to the Wakashio LSFO spill accident, considering actual geometry and weather information, which confirmed the practical feasibility of the present model.

Preparation and Oil Adsorption of Cellulose-graft-poly(butyl acrylate-N,N'-methylene Bisacrylamide)

With the advancement of industrial economies, incidents involving spills of petroleum products have become increasingly frequent. The resulting pollutants pose significant threats to air, water, soil, plant and animal survival, as well as human health. In this study, microcrystalline cellulose served as the matrix and benzoyl peroxide (BPO) as the initiator, while butyl acrylate (BA) and N,N'-methylene bisacrylamide (MBA) were employed as graft monomers. Through free radical graft polymerization, cellulose-graft-poly(butyl acrylate-N,N'-methylene bisacrylamide) [Cell-g-P(BA-MBA)], possessing oil-adsorbing properties, was synthesized. The chemical structure, elemental composition, surface morphology and wetting properties of the graft polymerization products have been characterized, using infrared spectroscopy, elemental analysis, scanning electron microscopy and contact angle testing. The adsorption properties of Cell-g-P(BA-MBA) for various organic solvents and oils were then assessed. The experimental results demonstrated that Cell-g-P(BA-MBA) exhibited a maximum adsorption capacity of 37.55 g/g for trichloromethane. Adsorption kinetics experiments indicated a spontaneous and exothermic process involving physical adsorption, conforming to the Freundlich isotherm model. Furthermore, adsorption kinetics experiments revealed that Cell-g-P(BA-MBA) displayed favorable reuse and regeneration performance, maintaining its adsorption capacity essentially unchanged over fifteen adsorption-desorption cycles.

Do distributions of diamondoid hydrocarbons accumulated in oil-contaminated fish tissues help to identify the sources of oil?

Identifying the sources of environmental oil contamination can be challenging, especially for oil in motile organisms such as fish. Lipophilic hydrocarbons from oil can bioaccumulate in fish adipose tissue and potentially provide a forensic "fingerprint" of the original oil. Herein, diamondoid hydrocarbon distributions were employed to provide such fingerprints. Indices produced from diamondoids were used to compare extracts from fish adipose tissues and the crude and fuel oils to which the fish were exposed under laboratory conditions. A suite of 20 diamondoids was found to have bioaccumulated in the dietary-exposed fish. Cross-plots of indices between fish and exposure oils were close to the ideal 1:1 relationship. Comparisons with diamondoid distributions of non-exposure oils produced overall, but not exclusively, weaker correlations. Linear Discriminatory Analysis on a combined set of 15 diamondoid and bicyclane molecular ratios was able to identify the exposure oils, so a use of both compound classes is preferable.

Comprehensive Two-Dimensional Gas Chromatography in Petroleum Derived Samples: A Review on Advances in Source and Weathering Studies of Spilled Oil

Since its introduction comprehensive two-dimensional gas chromatography (GC × GC) has been widely applied to analyze complex samples due to its enhanced peak capacity and selectivity, thereby increasing the number of identifiable peaks and improving coelution issues. Even though it is still undergoing development, GC × GC provides many advantages in the analysis of petroleum-derived samples, whether in reservoir geochemistry applications or in environmental studies associated with spilled oils. In general, it facilitates more thorough fingerprinting and compositional evaluation. In environmental studies, it helps enhance understanding of weathering processes and the environmental behavior of hydrocarbons, as its chromatographic retention indices can robustly estimate liquid vapor pressures, aqueous solubility and other physical chemical properties. This review presents a brief history of GC × GC instrumentation, discussing recent and significant advances in petroleum applications, from data handling techniques to reservoir geochemistry and environmental forensics, as well as some specific advantages achieved and certain limitations that continue to be encountered.

Characterization of the physical and weathering properties of low sulfur fuel oil (LSFO) and its spreading on water surface

Effective countermeasures against the marine pollution caused by spilled oil are enabled based on the understanding of its physical and weathering characteristics. In that sense, our knowledge of the newly enforced low-sulfur fuel oil (LSFO) needs to be secured urgently. First, we show that the oil viscosity increases with decreasing temperature, following the William-Landel-Ferry law developed for bunker oil. The meso-stable emulsion is achieved from the emulsion test, of which the viscosity is 10-100 times larger than the normal one. On the other hand, the portion of the evaporation of LSFO was insignificant (less than 3%), and thus, its effect on the oil properties is not substantial except the increase of the viscosity. In addition, we experimentally examine the spreading features (e.g., spreading area and rate) of LSFO on the water surface in the circulating water bath. We find that initially, the oil spreading area increases quite fast but saturates, of which the details are explained in terms of the driving and retarding forces involved in the spreading processes. Finally, considering the procured properties of the LSFO, we performed a numerical simulation of spreading LSFO on the water surface with a scale of hundred meters, which shows that our analysis can be extended to larger scales.

Applicability of oil adsorption pads based on properties of very-low sulfur fuel oil: Implications for oil spill remediation in a marine environment

Given the urgent need for continuous and diverse research on marine fuel oils, this study investigated the effects of the properties of fuel oil on its adsorption to adsorbent materials. Very low-sulfur fuel oil (VLSFO), which is increasingly being utilized in vessels, was tested to simulate adsorption from seawater at temperatures of 1, 15, and 25 °C. Temperature minimally affected the adsorbed amount of low-viscosity VLSFOs and high-sulfur fuel oils. Conversely, the amount of high-viscosity VLSFO adsorbed decreased sharply at 1 and 15 °C. The viscosity, pour point, aromatics, asphaltenes, and wax contents of fuel oils determined the amounts adsorbed on an adsorbent. Therefore, at low sea surface temperatures associated with VLSFO spills, adsorption may be challenging. These findings highlight the need to improve fuel oil quality to accommodate spills in the marine environment.

Analysis of sulfur compounds for crude oil fingerprinting using gas chromatography with sulfur chemiluminescence detector

Oil spills are a severe problem worldwide due to the resulting damage to marine and coastal ecosystems and to local economies. Identification of the source of spilled oils can be challenging, especially if the oils have undergone severe weathering. Due to their high durability, biomarker compounds (e.g. hopanes, steranes) are widely used for oil fingerprinting. Some sulfur-containing heterocyclic compounds e.g. alkylated dibenzothiophenes are also considered to be highly resistant. In this study, the use of Gas Chromatography with Sulfur Chemiluminescence Detection was investigated as a means of oil fingerprinting using the distribution the sulfur compounds in five different fresh and weathered crude oils. Chemometric analysis was also performed. The results indicate that the sulfur compounds distribution is unique for each crude oil. The distributions of the heavy sulfur compounds (i.e., C2DBTs and C3DBTs) are unchanged after weathering. Therefore, the GC-SCD technique can be considered to support the oil spill identification.

Fish Fingerprinting: Identifying Crude Oil Pollutants using Bicyclic Sesquiterpanes (Bicyclanes) in the Tissues of Exposed Fish

In the present study, we investigated the possibility of identifying the source oils of exposed fish using ratios of bicyclic sesquiterpane (bicyclane) chemical biomarkers. In the event of an oil spill, identification of source oil(s) for assessment, or for litigation purposes, typically uses diagnostic ratios of chemical biomarkers to produce characteristic oil "fingerprints." Although this has been applied in identifying oil residues in sediments, water, and sessile filtering organisms, so far as we are aware this has never been successfully demonstrated for oil-exposed fish. In a 35-day laboratory trial, juvenile Lates calcarifer (barramundi or Asian seabass) were exposed, via the diet (1% w/w), to either a heavy fuel oil or to Montara, an Australian medium crude oil. Two-dimensional gas chromatography with high-resolution mass spectrometry and gas chromatography-mass spectrometry were then used to measure selected ratios of the bicyclanes to examine whether the ratios were statistically reproducibly conserved in the fish tissues. Six diagnostic bicyclane ratios showed high correlation (r²  > 0.98) with those of each of the two source oils. A linear discriminatory analysis model showed that nine different petroleum products could be reproducibly discriminated using these bicyclane ratios. The model was then used to correctly identify the bicyclane profiles of each of the two exposure oils in the adipose tissue extracts of each of the 18 fish fed oil-enriched diets. From our initial study, bicyclane biomarkers appear to show good potential for providing reliable forensic fingerprints of the sources of oil contamination of exposed fish. Further research is needed to investigate the minimum exposure times required for bicyclane bioaccumulation to achieve detectable concentrations in fish adipose tissues and to determine bicyclane depuration rates once exposure to oil has ceased. Environ Toxicol Chem 2023;42:7-18. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Characterizations and comparison of low sulfur fuel oils compliant with 2020 global sulfur cap regulation for international shipping

The International Marine Organization 2020 Global Sulfur Cap requires ships to burn fuels with <0.50% S and some countries require <0.10% S in certain Sulfur Emission Control Areas but little is known about these new types of fuels. Using both traditional GC-MS and more advanced chromatographic and mass spectrometry techniques, plus stable isotopic, δ¹³C and δ²H, analyses of pristane, phytane and n-alkanes, the organic components of a suite of three 0.50% S and three 0.10% S compliant fuels were characterized. Two oils were found to be near identical but all of the remaining oils could be forensically distinguished by comparison of their molecular biomarkers and by the profiles of the heterocyclic parent and alkylated homologues. Oils could also be differentiated by their δ¹³C and δ²H of n-alkanes and isoprenoids. This study provides important forensic data that may prove invaluable in the event of future oil spills.

Multivariate analysis of otolith microchemistry can discriminate the source of oil contamination in exposed fish

The uptake of metals into the aragonite lattice of the fish otolith (ear-bone) has been used for decades as a historical record of exposure to metals in polluted environments. The relative abundance of two metals in particular, Ni and V, are used in forensic chemical analysis of crude oils to assist in confirming its origin. In this study we investigate the potential for metal accumulation in otoliths to act as a biomarker of exposure to crude oil. Using a 33-day static-renewal laboratory trial design, 56 juvenile Lates calcarifer (commonly known as Asian seabass or barramundi) were fed diets enriched with V (20 mg/kg), Ni (500 mg/kg), Fe (500 mg/kg), and two crude oils with distinctly different metals profiles: a heavy fuel oil (1% w/w) and a typical Australian medium crude (1% w/w). Fish exposed to crude oils showed Ba and Al retained in otoliths in a dose-dependent manner, but fish fed V-, Ni- and Fe-enriched diets showed no metal increase in otoliths, indicating that V, Ni and Fe are not incorporated into the otolith of L. calcarifer via dietary exposure. For crude oils, incorporation into otolith for many metals is likely limited due to porphyrin casing reducing their bioavailability. Principal components analysis (PCA) and subsequent linear discriminatory analysis (LDA) of selected otolith metals demonstrated that, even despite large variability in the metal abundances detected in otolith between individuals within the test groups (cv = 1.00), it is possible to discriminate between fish exposed to different crude oils using multivariate analysis of their otolith microchemistry.

A Novel Graphite-Based Sorbent for Oil Spill Cleanup

The performance of an innovative material based on expanded graphite, Grafysorber^® G+ (Directa Plus), has been tested through laboratory, tank, and confinement tests for oil removal in case of an oil spill and water treatment. In addition to the ability to retain oil, the possibility of reusing this material after regeneration via squeezing was also evaluated. As a comparison, the same experimental tests were conducted using polypropylene flakes (PP), the material currently most used to deal with spill accidents. Oils with different chemical and physical properties were used, namely kerosene, diesel, and crude oil. From the laboratory tests, the capacity of Grafysorber^® G+ to retain oil was found to be directly proportional to the viscosity of the latter, with adsorption values ranging from 76.8 g/g for diesel to 50.8 g/g for kerosene, confirming the potential of the innovative material compared to the PP. Cyclical use tests have confirmed certain reusability of the material, even if its adsorbent capacity decreases significantly after the first cycle and continues to decrease in subsequent cycles, but a less marked manner. Finally, some considerations based on the adsorption capacities were found to suggest that the adoption of the new material is also economically preferable, resulting in savings of 20 to 40% per kg of hydrocarbon treated.