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Microalgae have emerged as a promising source of biomass to produce renewable biofuels due to their ability to synthesize high-energy density compounds of commercial interest. This study proposes an approach for pilot-scale oil extraction, purification by fractional distillation, hydrocarbon characterization by gas chromatography coupled to mass spectrometry (GC-MS), evaluation of physicochemical parameters of the produced hydrocarbons, preliminary cost analysis, and challenges and future opportunities for green diesel on a commercial scale. Here, the microalgae Tetradesmus obliquus was cultivated in 12 m³ photobioreactors using biodigested swine waste as a culture medium. The resulting biomass was subjected to drying and harvesting, followed by oil extraction using a hot solvent extraction method, followed by distillation to purify the compounds. Three different extraction and distillation experiments were conducted, each using different solvent combinations. The results obtained revealed that extraction with a solvent blend, composed of hexane and ethanol, provided more significant yields compared to extraction with pure hexane. GC-MS analysis showed the presence of alkanes and alkenes in the oil samples, and the proportion of solvent used in the extraction directly influenced the production of alkanes. Additionally, specific hydrocarbons such as 4-methyl-1-decene, 8-heptadecene, 1-pentadecene, 9-heneicosene, and 2-dodecene were identified. The evaluation of the physicochemical parameters demonstrated that the calorific value of the distilled oil samples is within the range of typical values for petroleum diesel. However, it was observed that the distilled oil samples had higher sulfur content compared to conventional diesel. Regarding the cost analysis, it was found that it varies depending on the experimental conditions. In particular, the process using a solvent mixture of 70% hexane and 30% ethanol proved to be more economical than the others, since it extracted a greater quantity of oil with a lower initial biomass requirement. In summary, this microalgae-derived hydrocarbon production process is promising and offers insights for compound purification and future biofuel applications.

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The chemical composition of spilt oils from events that took place on the north-eastern coast of Brazil in 2019 and 2022 was investigated to better understand their sources, and post-spill processes. Oils from both events originated from different sources, based on their fingerprints, hydrocarbons composition and specific biomarkers, such as the C23 tricyclic terpane and oleanane. Despite the differences, the source rocks share similarities in paleoenvironments and depositional conditions and both oils suffered little weathering, mainly due to evaporation and dissolution. Our findings for 2019 spilt oil reinforce that it is a mixed product, enriched both in lighter n-alkanes and 25-norhopanes. Differently, the 2022 samples exhibited characteristics of a non-processed crude oil that originated from a paraffinic deposit in storage tanks. The molecular composition and diagnostic ratios reported for samples from these spill events help to establish baselines for ongoing monitoring of oil spills in marine ecosystems.

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The chemical composition of extracts (CEs) and essential oils (EOs) from Tetradenia riparia leaves, flower buds, and stems was analyzed. Antiproliferative activity against tumor cell lines, NO production inhibition, and antioxidant and antiviral activities were assessed. The CEs contained flavonoids, phenolic acids, coumarins, and saturated fatty acids. The EOs included monoterpenes, oxygenated sesquiterpenes, and diterpenes. NO production inhibition ranged from 76 to 247 µg mL-1, and antiproliferative activity exhibited GI50 between 20 and >204 µg mL-1, with low cytotoxicity (SI: 1.08 to 4.75). Reactive oxygen species inhibition ranged from 45 to 82%. Antioxidant activity varied when determined by the 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay (IC50: 0.51 to 8.47 mg mL-1) and ferric reducing antioxidant power (0.35 to 0.81 µM ferrous sulfate per mg). The reduction in ß-carotene-linoleic acid co-oxidation varied between 76.13 and 102.25%. The total phenolic content of CEs and EOs was 10.70 to 111.68 µg gallic acid mg-1. Antiviral activity against herpes simplex virus type 1 (HSV-1) showed an EC50 between 9.64 and 24.55 µg mL-1 and an SI between 8.67 and 15.04. Leaf EOs exhibited an EC50 of 9.64 µg mL-1 and an SI of 15.04. Our study unveils the diverse chemical composition and multifaceted pharmacological properties of T. riparia, demonstrating its potential as a valuable source of bioactive compounds for therapeutic applications.

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In 2019, there was an environmental catastrophe in Brazil, when more than 5000 tons of unknown origin crude oil invaded beaches and mangroves. Two years later, two monitoring areas were selected to study seahorses' offspring: Massangana River estuary (apparently healthy area) and Cocaia Island (affected area). Thirty-six reproductive events of Hippocampus reidi (Syngnathidae) couples from these two areas were monitored to analyze the offspring. At the apparently healthy area, no newborns with malformations were found. However, the offspring from Cocaia Island showed a mean of 19.73% (±5.23) malformations in newborns. It is argued that the toxic/teratogenic effects of polycyclic aromatic hydrocarbons have affected the population in two ways: directly through the induction of mutations in the germ cells of the species and through a drastic reduction of the population (bottleneck effect) whose density observed today recovered through consanguineous couplings, potentiating deleterious genotypes in the offspring. Environ Toxicol Chem 2024;43:1996-2004. © 2024 SETAC.

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This study assessed the effects of pollutants on Magallana gigas along a coastal zone with different levels of human activity: a highly impacted zone in the Bahía Blanca Estuary and a less impacted zone on the adjacent sandy beaches. Oysters collected in 2021 were analyzed for various factors, including metals, polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides, microplastics, oxidative stress and histology. Oysters of both environments exhibited detectable concentrations of all these pollutants in their tissues. However, the estuarine oysters showed higher concentrations of Zn, Cu and As and total PAHs than the beach oysters. Banned organochlorine pesticides were detected only in beach oysters. Estuarine oysters displayed morphological changes in their digestive gland including a reduction in the mean epithelial thickness of the tubule and elevated lipid peroxidation levels, indicating cellular damage. This study underscores the widespread presence of pollutants in M. gigas, indicating the need for effective strategies to safeguard coastal ecosystem health.

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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.

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In 2019, one of Brazil's most significant environmental disasters occurred, involving an oil spill that directly affected Pernambuco state. Contamination along the coast was evaluated by the quantification of polycyclic aromatic hydrocarbons (PAHs) in fifty seawater samples collected in the summer and winter of 2021. Analysis using fluorescence spectroscopy revealed that for all the samples, levels of dissolved/dispersed petroleum hydrocarbons (DDPHs) were higher than the regional baseline for tropical western shores of the Atlantic Ocean. GC-MS analyses quantified 17 PAHs in the samples, with highest total PAHs concentrations of 234 ng L-1 in summer and 33.3 ng L-1 in winter, which were consistent with the highest risks observed in ecotoxicity assays. The use of diagnostic ratios showed that the coast was impacted by a mixture of PAHs from petrogenic and pyrolytic sources. The results indicated the need for continuous monitoring of the regions affected by the 2019 spill.

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Polycyclic aromatic hydrocarbons (PAHs) are organic compounds ubiquitous in the environment and known for their toxic, mutagenic, and carcinogenic effects. These compounds can bioaccumulate in the biota and be transferred through trophic webs. The franciscana dolphin (Pontoporia blainvillei), as top predators, can be an environmental sentinels. Thus, this study aimed to provide data about PAHs concentration in their hepatic tissue collected on the coast of Espírito Santo (Franciscana Management Area, FMA Ia), Rio de Janeiro (FMA IIa), and São Paulo states (FMA IIb), in Southeastern Brazil. PAHs were detected in 86 % of franciscana dolphins (n = 50). The highest ∑PAHsTotal median concentration was reported in FMA Ia followed by FMA IIb and FMA IIa (1055.6; 523.9, and 72.1 ng.g-1 lipid weight, respectively). Phenanthrene was detected in one fetus and two neonates, showing maternal transfer of PAHs in these dolphins. Evaluating PAHs with potential toxic effects is of utmost importance for the conservation of a threatened species.

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In Ecuador, the regulatory framework for the remediation of petroleum-contaminated soils is based on predefined concentration endpoints for a selected range of petroleum hydrocarbon compounds. However, such approach may lead to over or under-estimation of the environmental risk posed by contaminated soils. In this study, the end-point remediation criteria according to Ecuadorian Environmental legislation were evaluated using different approaches. The first one was based on Total Extractable Petroleum Hydrocarbons (TEPH) and the second one on Total Bioavailable Petroleum Hydrocarbons (TBPH). Both were compared with ecotoxicological determinations using EC50 -Microtox® bioassay at 5 and 15 min of exposure. The correlation (R2) between EC50 values vs TEPH was of 0.2 and 0.25 for 5 and 15 min, respectively. Meanwhile, R2 between EC50 and TBPH was of 0.9 and 0.65 for 5 and 15 min, respectively, demonstrating a stronger correlation. Our results suggest that a contaminated site where the concentration of the TEPH is higher than the relevant regulatory concentrations may be deemed to present an acceptable risk even though their concentrations exceed the target values in soils. The results also challenge the notion that hormesis is associated with TEPH, contrary to some literature. This study is the first in Ecuador to propose incorporating bioavailability into environmental regulations, highlighting the need for further research to establish realistic and achievable remediation goals based on toxicity studies involving various trophic levels.

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This work presents the experimental assessment of a 20 mL batch reactor's efficacy in converting plastic and oil residues into biofuels. The reactor, designed for ease of use, is heated using a metallic system. The experiments explore plastic solubilization at various temperatures and residence times, employing a mixture of distilled water and ethylene glycol as the solvent. Initial findings reveal that plastic solubilization requires a temperature of 350 °C with an ethylene glycol mole fraction of 0.35, whereas 250 °C suffices with a mole fraction of 0.58. Additionally, the study includes a process simulation of a plant utilizing a double fluidized bed gasifier and an economic evaluation of the interesterification/pyrolysis plant. Simulation results support project feasibility, estimating a total investment cost of approximately $12.99 million and annual operating expenses of around $17.98 million, with a projected payback period of about 5 years.