Environmental Toxicology and Chemistry最新文献

Methyl 2-{[1-(5-fluoropentyl)-1H-indazole-3-carbonyl]amino}-3,3-dimethylbutanoate (5F-ADB), a potent synthetic cannabinoid, induces intense euphoria, hallucinations, and addiction, posing significant risks to human health. Current drug surveillance efforts lack data to identify drug abuse, and the environmental impacts of 5F-ADB entering aquatic systems via synthesis or use remain uncharacterized. To address these gaps, a multilevel assessment system (in vitro-invertebrate-vertebrate) was established to elucidate 5F-ADB metabolic pathways and identify robust biomarkers. Human liver microsomes (HLMs), Daphnia magna, and zebrafish were exposed to 5F-ADB, with metabolites profiled by high-performance liquid chromatography coupled with mass spectrometry. Metabolic pathways were inferred, and metabolite toxicity was evaluated. Results revealed 9, 11, and 22 metabolites in HLMs, D. magna, and zebrafish models, respectively. Dominant pathways in HLMs and zebrafish included ester hydrolysis, defluorinated hydroxylation, and combined ester hydrolysis/defluorinated hydroxylation. Daphnia magna metabolism primarily featured defluorinated hydroxylation, depentylation, and ester hydrolysis coupled with hydroxylation. Glucuronidation metabolites were exclusive to zebrafish. Based on abundance and stability, H-M4 (ester hydrolysis), D-M1 (ester hydrolysis/depentylation), and Z-M15 (ester hydrolysis/condensation) were identified as key biomarkers for HLMs, D. magna, and zebrafish, respectively. Toxicity assessments indicated reduced toxicity for most metabolites versus 5F-ADB. However, H-M7, D-M7, D-M11, and Z-M15 (products of ester hydrolysis/condensation or defluorinated hydroxylation/oxidation) exhibited comparable toxicity to the parent compound. Critically, D-M7 (defluorinated hydroxylation/oxidation) demonstrated heightened hydrophilicity and potentially elevated ecotoxicity in D. magna, warranting further ecological risk investigation. This study provides the first multitrophic metabolic characterization of 5F-ADB, delivering critical data for tracing illicit synthesis, monitoring drug use distribution, and evaluating environmental hazards of synthetic cannabinoids.

Syncrude's Base Mine Lake Demonstration (BML) is the first commercial demonstration of water-capped tailings technology in the oil sands industry, with the goal of developing into a self-sustaining aquatic ecosystem over time. The partitioning of organic components of residual bitumen and naphtha present in the fluid fine tailing is a critical control on their potential transport and biodegradation. Methanogenesis and associated methane ebullition observed in BML are associated with the transport of residual organic compounds to the lake surface, a process controlled by the physicochemical properties of the compounds involved. Though even comprehensive two-dimensional gas chromatography (GC × GC) is unable to resolve and/or identify every single compound from this mixture, we were able to use a GC × GC-based approach to estimate the physicochemical properties of the non-polar fraction of bitumen associated with gas bubbles trapped within ice from BML to assess their environmental behaviors. The modeled results indicated that the non-polar fraction of the transported bitumen generally exhibits low volatility (-5 < log PL <2.5 Pa), low solubility (-12 < log SwL<-1mol·m3), and high octanol-water partitioning coefficients (5 < log Ko-w <13). Furthermore, combining multiple partitioning coefficients enabled a first-order assessment of the aquatic bioaccumulation potential and terrestrial biomagnification potential of the detected compounds. The results indicated that the non-polar fraction of the transported bitumen is not likely to cause significant aquatic bioaccumulation or terrestrial biomagnification effects, due mainly to its high hydrophobicity. The ability to assess the environmental behavior of compounds that cannot be individually identified or whose physicochemical properties have yet to be characterized is an important capability in situations such as oil sands or elsewhere where complex mixtures of organic compounds are present.

The purpose of this article is to present a case study of the use of site-specific sediment toxicity data as a line of evidence for development of preliminary remediation goals for the protection of the community of benthic invertebrates in sediments of the Upper Fox River adjacent to the former Oshkosh, WI, manufactured gas plant (MGP). Standard 28-day laboratory toxicity tests with the freshwater amphipod, Hyalella azteca, were conducted. Various exposure metrics were examined to determine which metrics were the best predictor of toxicity. Metrics included concentrations of total polycyclic aromatic hydrocarbon (TPAH)13 and TPAH34 in sediment (with and without normalization to organic carbon), toxic units (TUs) estimated from concentrations of 34 PAHs measured in sediment, and TUs estimated from 34 PAHs measured in porewater using passive samplers (with and without the addition of organoclay to avoid fouling of passive samplers). Exposure-response models were used to evaluate the relationships between the various exposure metrics and toxicological responses. All of the exposure metrics provided relatively good fits of models to data and were used to calculate effect concentrations (EC20) predicted to cause 20% reduction in the endpoint (e.g., survival and biomass). The EC20 value of 119 mg/kg TPAH13 was selected for future use as a conservative and protective line of evidence to describe the nature and extent of MGP impacts at the site. The integrated approach outlined in this study presents a scientifically defensible method for establishing site-specific remediation goals that are protective of benthic communities.

Negligible depletion micro-extraction (nd-ME) is widely used for determining the freely dissolved concentration of pollutants. However, it typically requires a long equilibrium time. In this study, an in situ electrochemical approach based on nd-ME was developed to assess the sorption coefficient of methyl parathion (MP) onto humic acid, as well as the freely dissolved MP concentration in the real water samples, using a beta-cyclodextrin modified reduced graphene oxide composite electrode (β-CD/RGO/GCE). The sorption behavior of MP toward two representative humic acids-Acros humic acid (AcHA) and Suwannee River humic acid (SRHA)-across a dissolved organic carbon (DOC) range of 0 to 25 mg L-1 was investigated with the proposed method and validated using the conventional negligible depletion-solid phase micro-extraction (nd-SPME) technique. Equilibrium between freely dissolved MP and the β-CD/RGO composite was achieved within 16 min, representing a reduction to less than 1/22 of the time required by nd-SPME. Under equilibrium conditions, the obtained sorption coefficients (log KDOC) were 4.56 for AcHA and 4.58 for SRHA, which align closely with the values derived from nd-SPME (log KDOC = 4.23 for AcHA and 4.27 for SRHA). Moreover, the measured freely dissolved MP concentrations in water samples ranged from 3.96 to 4.44 μg L-1, basically consistent with the nd-SPME results (freely dissolved concentration, Cfree = 4.17-4.76 μg L-1), demonstrating the reliability of the proposed method. Meanwhile, if combined with a portable electrochemical workstation, this study holds promise for providing a method applicable to on-site detection of the freely dissolved concentration of various compounds.

Hyalella azteca is a North and Central American amphipod used worldwide to evaluate the toxicity of sediments and water matrices. Although current evaluation procedures extensively use H. azteca standard life-cycle tests, there are no protocols specifically designed in this species to assess contaminant effects on reproductive processes and embryonic development at the individual level. Based on a methodology available in European gammarids, this study aimed to initiate the development of a chronic test, leveraging an advanced knowledge of the female reproductive cycle in these amphipods. Parameters such as molting advancement, embryonic development in marsupium, and realized fecundity were the fundamental endpoints of the proposed 2-week biotest. First, females were monitored between two egg-laying events at three temperatures (16 °C, 20 °C, 24 °C) to describe the molting process and the embryonic development. Afterwards, we proposed a biotest consisting of exposing couples for one reproductive cycle (10 days at 24 °C) starting with females in AB molting stage (postmolting time < 24 hr). Molting impairment and embryonic development are assessed at a first time of observation (Day 6), followed by a measurement of realized fecundity at Day 13 (3 days postlaying in clean water), that is, embryo number in the maternal pouch for the second reproductive cycle. Four control experiments and one exposure test to cadmium (at 1 and 5 µg L-1) validated the robustness and the sensitivity of the method. As in other amphipods, cadmium inhibited the molting and embryonic development in Hyalella. The proposed Hyalella reprotoxicity test offers a rapid tool for specifically assessing reproductive impairments caused by chemicals and environmental matrices, complementing the standardized life-cycle tests available in this species for population-level toxicity assessment.

This study focuses on evaluating the relationship between the co-occurrence and speciation of trace metallic elements with reference to the acute toxicity observed to Daphnia magna. Calculations were performed on data from the regular monitoring of an industrial effluent. The effluent generally met regulatory discharge criteria for metal(loid) concentrations (Fe > Zn > Al > Cu > Ni > As > Cd > Pb), but sporadic toxicity was observed, indicating that the interactions between trace metallic elements might affect toxicity. The methodological approaches include correlation analyses, one-way analyses of variance, principal component analyses, hierarchical cluster analyses, and geochemical calculations performed for the purpose of assessing trace metallic elements speciation. The results suggest that Cd and Cu are the primary contributors to toxicity while Fe could inhibit toxicity. Moreover, speciation calculations suggest that the bioavailable forms of Cd2+ and Cu2+, even at sublethal levels, could play a pivotal role in the observed toxicity. The analyses of changes in correlations between pairs of elements in nontoxic versus toxic effluents further suggest synergistic Cu-Cd and antagonistic Fe effects on toxicity. The approach developed in the present study has the potential for wider implementation. The identification of statistical links between the concentrations of different contaminants and toxicity could facilitate toxicant identification, particularly for effluents that meet regulatory standards in terms of contaminant concentrations.

Marine sediments play a key role in the biogeochemical cycle of mercury, acting as sinks that facilitate its accumulation in marine organisms and posing a risk to the food security of coastal communities and human health. This study determined the temporal dynamics and environmental variables that influence the transfer of total mercury in dry weight from sediments to fish in artisanal fishing areas of the Pacific and Caribbean coasts of Colombia. The concentrations of total mercury in dry weight were analyzed in the sediment, seston, and muscle (dry wt) of eight fish species caught using two artisanal fishing methods (net and hook), during dry and wet seasons. Biota-sediment accumulation factor (BSAF) was calculated to estimate the transfer of mercury from the sediments to fish. All fish had a BSAF of >1, indicating accumulation of total mercury in dry weight in fish tissues, and values of >2 on average, suggesting their potential as macroconcentrators. The BSAF was higher in demersal fish (family Lutjanidae; 56.7 ± 32.3), and in the Caribbean, where it was up to four times higher than that in the Pacific. The BSAF increased during the wet season, when the lowest concentrations of mercury were in the sediments, due to an increase in bioavailability associated with organic matter. The study identified three patterns of mercury transfer between species, influenced by variables such as organic matter content, total dissolved solids, and environmental mercury concentrations. These results demonstrate a complex dynamic of mercury mobilization controlled by environmental factors and highlight the importance of considering climatic conditions, habitat, and community composition in assessing mercury risks in coastal ecosystems.

Microplastic (MP) pollution is a worldwide concern and represents an ecological threat to the aquatic environment, particularly freshwater ecosystems. It can pose risks to the health of organisms and potentially lead to bioaccumulation of these tiny particles in the food chain. This study focused in MP determination on three species of freshwater mussels (Unio gibbus, Unio ravoisieri, and Unio dureui) as potential models for ecological assessment in the Sejenane stream in Northern Tunisia. To achieve this, we assessed ingested microplastics in the gills and digestive gland tissues of these mussels. Raman microspectroscopy was used to examine and identify microparticles with size ranges under 5,000 μm. Our results indicated that the microparticles are categorized into three sequential size ranges: S1 (< .45-1.2 μm), S2 (< 1.2-3 μm), and S3 (≥ 3 μm). Over 50% of the S1 class was found in Unio gibbus. Our findings showed a higher occurrence of the S3 size class of microplastics (≥ 3 µm) in the gills of all studied mussels. More than 60% of the S3 class was identified in Unio durieui, followed by S2 (< 3-1.2 µm) and S1 (< 1.2-.45 µm). Polyethylene-vinyl acetate, polypropylene, low-density polyethylene, polyethylene terephthalate, high-density polyethylene, and polyethylene are the six different types of polymers that were found. Polyethylene terephthalate emerged as the dominant polymer type in Unio dureui, accounting for up to 59% of the gills and 55% of the digestive gland. Overall, it seems that freshwater mussels are capable of accumulating microplastics from environmental contamination. However, further studies in diverse freshwater ecosystems are necessary to validate the findings of this study.

Adverse outcome pathways (AOPs) describe mechanisms of toxicity by connecting molecular events with outcomes at higher levels of biological organization. Computational AOPs (cAOPs), constructed using existing toxicological data, can accelerate the early stages of AOP development, which is often a time-consuming and resource-intensive process. In this study, an integrative network-based framework was developed to construct cAOPs, with a particular focus on elucidating the toxicity of organic mercury in fish. First, 124 organic mercury compounds, associated fish toxicity endpoints, and proteins were curated from the Comparative Toxicogenomics Database and ECOTOX database, followed by molecular docking to identify novel interactions with 16 zebrafish protein orthologs. Subsequently, toxicity endpoints and identified molecular interactions were standardized and harmonized using established ontologies and AOP-Wiki. These data were integrated with event relationship information from AOP-Wiki and published literature to construct an organic mercury-associated toxicity network, comprising 197 nodes and 243 edges, which was subsequently filtered using AOP definition-based criteria to identify biologically relevant pathways. Further, these pathways were ranked based on their novelty with respect to existing AOPs in AOP-Wiki, resulting in the proposal of four novel cAOPs describing glutathione peroxidase binding or altered metallothionein levels leading to neurological manifestations or dysbiosis in fish. Overall, this study presents an integrative network-based framework for constructing cAOPs applicable to diverse contaminants and species, supporting new approach methodologies for toxicological risk assessment.

Drinking water treatment residuals (DWTRs) produced as a result of the coagulation-flocculation process during water treatment are considered waste materials. Characterization of this material shows its ability to sequester metals and other anionic and cationic chemicals. Drinking water treatment residuals from two different drinking water treatment plants located in Wyoming and Oregon were evaluated for their ability to function as viable capping materials of metal-contaminated sediments. The contaminated sediments tested were either spiked with a mixture of metals, 1 mg/kg of Cu, Zn, Cd, and Pb, or coming from an intertidal sediment collected at a U.S. Naval Air Station. A Gust chamber experiment was used to determine metal fluxes from these sediments into the overlying water with applied hydrodynamic stress of 0.05 and 0.4 Pa in the absence and presence of DWTR as a capping material. The DWTR effectively reduced the amount of metal released to the overlying waters to a value below the National Recommended Aquatic Life Criteria for Cr, Cu, Pb, and Zn, but slightly above the value for Cd. The toxicity of these waters was tested with an in vivo 96 hr fathead minnow survival assay. In the absence of capping, all the fry died within 1 hr. Capping with DWTR from Wyoming effectively reduced contamination, and 95% of the fish survived. The DWTR from Oregon was less successful, but the survival of fish was equivalent to diluting the original contaminated waters by a factor of 100. Drinking water treatment residual effectively reduced metallothionein in fish, a biomarker of metal contamination, corroborating the survival experiments. These results suggest that DWTRs may be very effective for remediation of metal-contaminated sites.