We assessed the performance of taxonomic and several functional trait-based approaches in the assessment of spatial and temporal patterns of dusky flounder (Syacium papillosum) parasite assemblages along the Yucatan shelf to determine their potential as bioindicators of marine chemical pollution. Fish specimens were collected throughout three research cruises that took place in 2015, 2016 and 2018. In addition to the traditional taxonomic approach, four trait-based approaches were performed including community-weighted means (CWM), functional trait niche (FTN), functional groups (FGs), and Rao's functional diversity (FD). Significant spatial and temporal variations in parasite communities were detected using the taxonomic approach. In general, these variations were also reflected in the four trait-based approaches performed, indicating that changes in taxa composition and abundance also resulted in functional composition shifts. Resemblance matrices of both taxonomic and functional trait approaches were significantly correlated. Variations in taxonomic and trait-based composition using the four approaches were significantly correlated with depth, and at least one chemical pollutant variable. Feeding mode, transmission, life stage and attachment structure displayed spatial variability and significant correlations with predictor variables, which indicates that this set of attributes functions as a good surrogate for assessing variations in the functional composition of flatfish parasite communities in relation to pollution. FTN and CWM were the approaches that best detected spatio-temporal variation. CWM and FD were best suited for detecting pollution gradients. These results reveal the feasibility of using trait-based approaches to assess marine parasite communities as bioindicators of chemical pollution. Functional traits of marine metazoan parasites are as good indicators of the effect of oil pollution as taxonomic diversity. This may be a time-saving and cost-effective approach to performing environmental assessments.

Oil spills are a serious environmental problem. To better support risk assessment and pollution control for oil spills, a good understanding of oil transport in the environment is required. This study focused on the numerical simulation of the nearshore oil behaviors based on computational fluid dynamics. Based on the Navier-Stokes momentum equations for an incompressible viscous fluid and volume of fluid (VOF) method, a 3D numerical model of three-phase transient flow was developed. The wave number, averaged flow velocity and oil properties would affect the oil spread extent and the oil volume fraction. The higher the averaged flow velocity and wave number, the lower the oil concentration, and the faster the horizontal movement of the oil. The spilled oil may move to contact the seafloor by increasing the averaged flow velocity at the inlet boundary. Through increasing the wave number, the oil would stay near the water surface. In the nearshore, where the wave is the main seawater motion, the oil containment boom should be set preferentially to the direction of wave transmission for oil cleaning. This study shows that by doubling the wave number and increasing the averaged flow velocity (ten times) at the same time, the maximum oil volume fraction would be reduced by around 32%. Finally, the water temperature had no significant impact on the oil migration, and the impact of evaporation should be considered in the simulation.

This study develops an oil spill environmental vulnerability model for predicting and mapping the oil slick trajectory pattern in Kota Tinggi, Malaysia. The impact of seasonal variations on the vulnerability of the coastal resources to oil spill was modelled by estimating the quantity of coastal resources affected across three climatic seasons (northeast monsoon, southwest monsoon and pre-monsoon). Twelve 100 m³ (10,000 splots) medium oil spill scenarios were simulated using General National Oceanic and Atmospheric Administration Operational Oil Modeling Environment (GNOME) model. The output was integrated with coastal resources, comprising biological, socio-economic and physical shoreline features. Results revealed that the speed of an oil slick (40.8 m per minute) is higher during the pre-monsoon period in a southwestern direction and lower during the northeast monsoon (36.9 m per minute). Evaporation, floating and spreading are the major weathering processes identified in this study, with approximately 70% of the slick reaching the shoreline or remaining in the water column during the first 24 h (h) of the spill. Oil spill impacts were most severe during the southwest monsoon, and physical shoreline resources are the most vulnerable to oil spill in the study area. The study concluded that variation in climatic seasons significantly influence the vulnerability of coastal resources to marine oil spill.

Though many studies pertaining to soil bioremediation have been performed to study the microbial kinetics in shake flasks, the process efficiency in column tests is seldom. In the present study, soil columns tests were carried out to study the biodegradation of soil contaminated with a high concentration of diesel (≈19.5 g/kg) petroleum hydrocarbons expressed as C₁₀–C₅₀. Experiments were done with crude enzymatic cocktail produced by the hydrocarbonoclastic bacterium, Alcanivorax borkumensis. A. borkumensis was grown on a media with 3% (v/v) motor oil as the sole carbon and energy source. The effects of the enzyme concentration, treatment time and oxidant on the bioremediation efficiency of C₁₀–C₅₀ were investigated. A batch test was also carried out in parallel to investigate the stability of the enzymes and the effect of the biosurfactants on the desorption and the bioconversion of C₁₀–C₅₀. Batch tests indicated that the biosurfactants significantly affected the desorption and alkane hydroxylase and lipase enzymes, maintained their catalytic activity during the 20-day test, with a half-life of 7.44 days and 8.84 days, respectively. The crude enzyme cocktail, with 40 U/mL of lipase and 10 U/mL of alkane hydroxylase, showed the highest conversion of 57.36% after 12 weeks of treatment with a degradation rate of 0.0218 day⁻¹. The results show that the soil column tests can be used to optimize operating conditions for hydrocarbon degradation and to assess the performance of the overall bioremediation process.

The well-known toxicity of conventional chemical oil spill dispersants demands the development of alternative and environmentally friendly dispersant formulations. Therefore, in the present study we have developed a pair of less toxic and green dispersants by combining lactonic sophorolipid (LS) biosurfactant individually with choline myristate and choline oleate ionic liquid surfactants. The aggregation behavior of resulted surfactant blends and their dispersion effectiveness was investigated using the baffled flask test. The introduction of long hydrophobic alkyl chain with unsaturation (attached to choline cation) provided synergistic interactions between the binary surfactant mixtures. The maximum dispersion effectiveness was found to be 78.23% for 80:20 (w/w) lactonic sophorolipid-choline myristate blends, and 81.15% for 70:30 (w/w) lactonic sophorolipid-choline oleate blends at the dispersant-to-oil ratio of 1:25 (v/v). The high dispersion effectiveness of lactonic sophorolipid-choline oleate between two developed blends is attributed to the stronger synergistic interactions between surfactants and slower desorption rate of blend from oil-water interface. The distribution of dispersed oil droplets at several DOR were evaluated and it was observed that oil droplets become smaller with increasing DOR. In addition, the acute toxicity analysis of developed formulations against zebra fish (Danio rerio) confirmed their non-toxic behavior with LC₅₀ values higher than 400 ppm after 96 h. Overall, the proposed new blends/formulations could effectively substitute the toxic and unsafe chemical dispersants.

The Peace-Athabasca Delta (PAD) receives a mixture of hydrocarbons from biogenic, pyrogenic, and petrogenic processes. Source apportionment in the PAD has focussed on polycyclic aromatic compounds (PACs), which are ubiquitous in the environment and susceptible to weathering. In contrast, petroleum biomarkers of terpanes, hopanes, and steranes are degradation-resistant organic compounds found uniquely in petroleum products that can identify the input and origin of petrogenic hydrocarbons (PHCs). We provide an analysis of environmentally-relevant PHCs (including n-alkanes, PACs, and petroleum biomarkers) in surficial sediments of strategically selected lakes in the Athabasca and Peace deltas and adjacent boreal uplands. Alkanes were found to be predominately biogenic in all lakes. PAC sources were identified as wood combustion in the upland boreal lakes, a mixture of petrogenic and pyrogenic combustion in two closed-drainage lakes in the Peace Delta, and predominately petrogenic in two flood-prone Athabasca Delta lakes. Using multivariate analyses, raw Alberta oil sands were identified as a potential source of PHCs to the two flood-prone lakes in the Athabasca Delta. Biomarkers of terpanes and hopanes were identified in the Peace Delta and boreal uplands, likely from bitumen and transported atmospherically. These findings validate the use of petroleum biomarkers as tracers for bituminous sands in surficial lake sediments and their potential use in paleolimnological investigations at the PAD to improve understanding of relative roles of natural and industrial processes on far-field deposition of PHCs.

The response of freshwater invertebrates following accidental releases of oil is not well understood. This knowledge gap is more substantial for unconventional oils such as diluted bitumen (dilbit). We evaluated the effects of dilbit on insect emergence and benthic invertebrates by conducting experimental spills in limnocorrals (10-m diameter; ~100-m³) deployed in a boreal lake at the IISD-Experimental Lakes Area, Canada. The study included seven dilbit treatments (spill volumes ranged from 1.5 L [1:66,000, oil:water, v/v] to 180 L [1:590, oil:water, v/v]), two controls, and additional lake reference sites, monitored for 11 weeks. Invertebrate emergence declined at the community level following oil addition in a significantly volume-dependent manner, and by 93–100 % over the 11 weeks following the spill in the highest treatment. Dilbit altered community structure of benthic invertebrates, but not abundance. One-year post-spill and following oil removal using traditional skimming and absorption techniques, benthic richness and abundance were greater among all treatments than the previous year. These results indicate that recovery in community composition is possible following oil removal from a lake ecosystem. Research is needed concerning the mechanisms by which surface oil directly affect adult invertebrates, whether through limiting oviposition, limiting emergence, or both. The response of benthic communities to sediment tar mats is also warranted.

Pollution damages ecosystems around the globe and some forms of pollution, like oil pollution, can be either man-made or derived from natural sources. Despite the pervasiveness of oil pollution, certain organisms are able to colonise polluted or toxic environments, yet we only have a limited understanding of how they are affected by it. Here, we analysed phenotypic responses to oil pollution in guppies (Poecilia reticulata) living in oil-polluted habitats across southern Trinidad. We analysed body-shape and life-history traits for 352 individuals from 11 independent populations, six living in oil-polluted environments (including the naturally oil-polluted Pitch Lake), and five stemming from non-polluted habitats. Based on theory of, and previous studies on, responses to environmental stressors, we predicted guppies from oil-polluted waters to have larger heads and shallower bodies, to be smaller, to invest more into reproduction, and to produce more but smaller offspring compared to guppies from non-polluted habitats. Contrary to most of our predictions, we uncovered strong population-specific variation regardless of the presence of oil pollution. Moreover, guppies from oil-polluted habitats were characterised by increased body size; rounder, deeper bodies with increased head size; and increased offspring size, when compared to their counterparts from non-polluted sites. This suggests that guppies in oil-polluted environments are not only subject to the direct negative effects of oil pollution, but might gain some (indirect) benefits from other concomitant environmental factors, such as reduced predation and reduced parasite load. Our results extend our knowledge of organismal responses to oil pollution and highlight the importance of anthropogenic pollution as a source of environmental variation. They also emphasise the understudied ecological heterogeneity of extreme environments.

Sodium percarbonate (SPC, 2Na₂CO₃∙3H₂O₂), is a compound that can be used under multiple environmental applications. In this work, SPC was employed as oxidant in the treatment of soil contaminated with diesel oil. The soil samples were collected during the earthmoving stage of RNEST Oil Refinery (Petrobras), Brazil. Then, the samples were air-dried, mixed and characterized. Subsequently, raw soil was contaminated with diesel and treated by photo-Fenton reaction (H₂O₂/Fe²⁺/UV). SPC played a significant role in the generation of hydroxyl radicals under the catalytic effect of ferrous ions (Fe²⁺), hydrogen peroxide (H₂O₂) and radiation. These radicals provoked the photodegradation of polycyclic aromatic hydrocarbons (PAHs), in the soil remediation. A factorial design 3³ was carried out to assess the variables which most influenced the decrease in total organic carbon (TOC). The study was performed with the following variables: initial concentration of [H₂O₂] and [Fe²⁺], between 190.0 and 950.0 mmol L⁻¹ and 0.0–14.4 mmol L⁻¹, respectively. UV radiation was supplied from sunlight, blacklight lamps, and system without radiation. All experiments were performed with 5.0 g of contaminated soil in 50.0 mL of solution. The initial concentration of Fe²⁺ showed the statistically most significant effect. The oxidation efficiency evaluated in the best condition showed a decrease from 34,765 mg kg⁻¹ to 15,801 mg kg⁻¹ in TOC and from 85.750 mg kg⁻¹ to 20.770 mg kg⁻¹ in PAHs content. Moreover, the sums of low and high molecular weight polycyclic aromatic hydrocarbons (LMW-PAHs and HMW-PAHs) were 19.537 mg kg⁻¹ and 1.233 mg kg⁻¹, respectively. Both values are within the limits recommended by the United Sates Environmental Protection Agency (USEPA) and evidenced the satisfactory removal of PAHs from contaminated soil, being an alternative to classic oxidation protocols.

The valorization of municipal solid waste incineration bottom and fly ashes (IBA and IFA) as catalysts for thermochemical plastic treatment was investigated. As-received, calcined, and Ni-loaded ashes prepared via hydrothermal synthesis were used as low-cost waste-derived catalysts for in-line upgrading of volatile products from plastic pyrolysis. It was found that both IBA and air pollution control IFA (APC) promote selective production of BTEX compounds (i.e., benzene, toluene, ethylbenzene, and xylenes) without significantly affecting the formation of other gaseous and liquid species. There was insignificant change in the product distribution when electrostatic precipitator IFA (ESP) was used, probably due to the lack of active catalytic species. Calcined APC (C-APC) demonstrated further improvement in the BTEX yield that suggested the potential to enhance the catalytic properties of ashes through pre-treatment. By comparing with the leaching limit values stated in the European Council Decision, 2003/33/EC for the acceptance of hazardous waste at landfills, all the ashes applied remained in the same category after the calcination and pyrolysis processes, except the leaching of Cl⁻ from the ESP, which was around the borderline. Therefore, the use of ashes in catalytic reforming application do not significantly deteriorate their metal leaching behavior. Considering its superior catalytic activity towards BTEX formation, C-APC was loaded with Ni at 15 and 30 wt%. The Ni-loading favored an increase in overall oil yield, while reducing the gas yield when compared to the benchmark Ni loaded ZSM catalyst. However, Ni addition also caused the formation of more heavier hydrocarbons (C20–C35) that would require post-treatment to recover favorable products like BTEX.