Environmental Toxicology and Chemistry最新文献

Year-round neonicotinoids detections in waterways pose a threat to aquatic ecosystems and drinking water supplies. Neonicotinoids, and increasingly diamides, are being used in the Canadian Prairies, but there is a paucity of detection and concentration data in streams and rivers. We report on neonicotinoids and diamides in 16 streams in southern Saskatchewan, Canada between 2017 and 2019. Approximately half of all samples had measurable levels of at least one insecticide, generally below guidelines. Thiamethoxam was most frequently detected across sites (42%), followed by clothianidin (18%) and imidacloprid (9%), while diamide detections differed with location. Most samples with detections contained at least one of thiamethoxam, clothianidin, or imidacloprid (98%). About 15% of samples between 2018 and 2019 detected diamides, reflecting their increasing use in Canada. While thiamethoxam and clothianidin concentrations were similar between rain events and snowmelt, their average daily loads were greatest during snowmelt (p < 0.05); suggesting overwintering and spring freshet as a significant source to streams. Generally, agriculturally intensive subwatersheds dominated by canola and cereals had higher neonicotinoid concentrations, yet crop cover and sites explained a small proportion of the variance. Neither site, crop, flow, or year considerably accounted for the large variation in detections, suggesting a complexity of factors. Based on probability distributions, exceedances of 7% to 15% were observed for thiamethoxam, clothianidin, and imidacloprid when compared to a highly protective chronic predicted no-effect concentration guideline value, suggesting limited acute or chronic risk in these systems. The variation of insecticide concentrations reflects crop practices, precipitation, prairie hydrology, agricultural practices, and environmental conditions, and highlights the need for improved monitoring across Canada to better understand processes affecting their distribution and risk.

Of the many hypotheses attributed to the global decline in shorebirds, an important one is the exposure to contaminants, particularly to wintering shorebirds. However, there is limited information available on contaminant levels in winter migrant shorebirds, especially within the Central Asian Flyway (CAF). This research gap is addressed in this study on total mercury (THg) contamination in 10 species of long-distance migrant shorebirds along the west coast of India from 2019 to 2021. Of the 10 species studied, the highest concentration of THg was reported in the droppings of Common Redshank in the mangroves (81.29 ± 6.82 mg/kg wet wt) and the lowest was reported in Little Stint in sand beach (17.40 ± 2.14 mg/kg wet wt). The Kadalundi-Vallikunnu Community Reserve (KVCR) and its adjacent sand beaches serve as vital stop-over sites within the CAF, catering to the nutritional needs of various migratory shorebirds, including transoceanic, oversummering, and locally moving species. This research offers solid evidence of THg concentration in predators occupying high trophic levels of the coastal ecosystems in the KVCR and surrounding areas. Understanding the extent and impact of THg concentration on both organisms and their habitat is crucial. The study highlights a significant increase of THg concentration across the years. Additionally, it provides essential information to support extensive, long-term biomonitoring efforts aimed at conserving shorebirds regionally and globally.

Hydroxylated polychlorinated biphenyls (OH-PCBs) are potential endocrine disruptors due to their interaction with nuclear receptors. However, experimental evaluation of their estrogenic activity is costly and time-consuming, limiting data availability. In this study, quantitative structure-activity relationship (QSAR) models were constructed using linear discriminant analysis (LDA) and decision tree (DT) with both 2D autocorrelation and arithmetic residuals in K-groups analysis (ARKA) descriptors to classify OH-PCBs as agonists or nonagonists of estrogen receptors (ERα and ERβ). For the ERα dataset, the training, test, and cross-validation set accuracies were 89.2%, 84.0%, and 88.0% for the LDA model developed with 2D autocorrelation descriptors (Model I); 89.2%, 72.0%, and 84.9% for the DT model developed with 2D autocorrelation descriptors (Model II); and 89.2%, 80.0%, and 87.0% for the ARKA-based model (Model V). Area under receiver operating characteristic (AUC-ROC) values of 0.959, 0.903, and 0.954 were obtained for Models I, II, and V respectively. For the ERβ dataset, the training, test, and cross-validation set accuracies were 90.5%, 84.0%, and 87.9% for the LDA model constructed with 2D autocorrelation descriptors (Model III); 89.2%, 68.0%, and 83.9% for the DT model constructed with 2D autocorrelation descriptors (Model IV); and 87.8%, 80.0%, and 84.9% for the ARKA-based model (Model VI). Values for AUC-ROC of 0.966, 0.892, and 0.945 were obtained for Models III, IV, and VI respectively. Overall, the QSAR models reported in this article provide a reliable and efficient approach for screening OH-PCBs for estrogenic activity, offering valuable tools for environmental risk assessment, with ARKA descriptors serving as effective alternatives to conventional descriptors.

The buildup of pollutants on impervious surfaces, and their subsequent flush into the environment within stormwater, could worsen with expected increases in prolonged dry periods and extreme rain events due to climate change. As such, the monitoring and treatment of urban stormwaters is becoming a high priority. Of particular interest is road runoff in urban areas, which has been found to be acutely lethal to salmonids and frequently contains elevated concentrations of metals and organic contaminants. In this study, samples of road runoff were collected in the Metro Vancouver area of British Columbia, Canada, and assessed for acute lethality to rainbow trout (Oncorhynchus mykiss). Three of the four stormwaters tested exhibited 100% mortality in the 96-hr test. Stormwater toxicity was demonstrated to be reduced by treatment in a rain garden. Phase I Toxicity Identification Evaluation (TIE) techniques initially identified a metal as the cause of toxicity in one stormwater, which was determined to be zinc after Phase II/III TIE testing. The second stormwater sample revealed an organic constituent to be responsible for toxicity, and subsequent TIE testing implicated N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine-quinone (6PPD-Q). The potential contribution of 6PPD-Q to toxicity was assessed by performing TIE techniques on a standard solution of 6PPD-Q in parallel with the stormwater. Chemical analysis of 6PPD-Q using Condensed-Phase Membrane Introduction Mass Spectrometry was used to support toxicity assessments. This is the first study to use the TIE approach to provide a toxicity profile for 6PPD-Q.

Obtaining clean water is a global priority, as emphasized by the United Nations Sustainable Development Goal 6, which aims to ensure availability and sustainable management of water and sanitation for all. Pharmaceutical pollutants are becoming more prevalent in aquatic environments, triggering public health concerns, negative environmental impacts, and the development of antibiotic resistance. Microalgae hold great potential for bioremediation of antibiotics, although most of the studies to date supporting these observations rely on conditions where artificial wastewater contained one or a few antibiotics. In this study, Chlorella sorokiniana was used to assess the removal of a mixture of 10 antibiotics selected and tested considering environmentally relevant antibiotic concentrations based on data from the National Health Service (United Kingdom). The selected antibiotics had a risk quotient > 1 as calculated by the ratio of predicted environmental concentration (PEC) to predicted no effect concentration. The experimental antibiotic concentration tested for each antibiotic corresponded to their PEC values. After 19 days of incubation, the β-lactam class (amoxicillin, penicillin V, cephalexin) showed the highest percentage of removal (51-85), followed by trimethoprim (24), oxytetracycline (6), metronidazole (6), and sulfamethoxazole (2). Different mechanisms, that is, biodegradation, photodegradation, bioadsorption, and bioaccumulation, were involved at variable range. Increase in algal biomass was observed concomitantly to decrease in the concentration of the tested antibiotics, suggesting their use as a carbon source for cellular growth. In addition, levels of dissolved ammonium, nitrate, phosphate, and chemical oxygen demand, decreased by 88%, 22%, 100%, and 10%, respectively. Our study confirmed the ability of C. sorokiniana to biodegrade antibiotics while also effectively reducing key nutrient loadings.

Current standard test methods for assessing biodegradation of chemicals are laborious and not suited for high-throughput screening of chemicals because of both the required volume of the test medium and the limited possibility for automation of measurements of biodegradation. A high-throughput method (HTM) should be miniaturized, suitable for automation, and based on generic parameters that can indicate biodegradation of any chemical. The aim of this study was to develop an HTM based on bacterial proliferation (i.e., growth) as an indicator of biodegradation, measured by flow cytometry. Natural bacterial communities were exposed to reference chemicals in 96-well plates for up to 14 days at 19 °C and the results compared with parallel standard biodegradation screening tests for freshwater (Organisation for Economic Co-operation and Development [OECD] 301F) and seawater (OECD 306). Increased bacterial growth, compared with nonexposed inocula, was used as an indication of biodegradation. Sodium benzoate induced a significant growth response that corresponded to the biodegradation experiments in both freshwater and marine water. Aniline induced a lower frequency of significant growth compared with the frequency of positive biodegradation results, whereas caffeine induced a higher frequency and more rapid growth response compared with biodegradation results. This shows the potential for an HTM for biodegradation testing using bacterial growth.

Pharmaceuticals and personal care products (PPCPs) are widely detected in aquatic environments. However, recent studies on the environmental occurrence of currently used PPCPs in Japan are limited. In this study, a nationwide monitoring initiative focusing on PPCPs was undertaken to investigate the occurrence and fate of PPCPs in aquatic environments in Japan. A total of 700 samples were collected and analyzed from 2018 to 2022. Ninety-one PPCPs were detected in the analyzed samples. Three PPCPs (N, N-diethyl-meta-toluamide [DEET], salicylic acid, and crotamiton) were detected at particularly high frequencies, with a prevalence exceeding 99% of analyzed samples. Seasonal variations were observed for several PPCPs across multiple rivers, with concentrations generally increasing during fall/winter and decreasing during spring/summer (except DEET) throughout the sampling period. The detection frequencies and concentrations were higher in PPCPs with higher domestic prescription amounts. Some PPCPs, such as acetylsalicylic acid, exhibited low frequencies and concentrations despite high domestic prescription amounts, suggesting transformation into metabolites or degradates in the aquatic environment. The contribution of sewage treatment plant effluent to the PPCP concentrations in the environment was estimated by examining the correlation between each PPCP and sucralose concentration. Sewage effluents appeared to be a significant contributor to the majority of target PPCPs; however, DEET and certain other PPCPs may originate from alternate sources. This study is the first to provide a comprehensive assessment of the occurrence and fate of PPCPs in Japan's aquatic environment. Future research should assess the environmental and human health risks of these PPCPs and identify the occurrence of their metabolites or degradates in the aquatic environment.

Per- and polyfluoroalkyl substances (PFAS) are thousands of toxic synthetic chemicals that bioaccumulate and persist in the environment. They are known to cause immunotoxicity, organ damage, endocrine disruption, and reproductive impairments in wildlife such as sea otters (Enhydra lutris). However, there is limited information on the distribution of these chemicals across the northeastern Pacific, and baseline data are missing to assess their potential impacts on sea otters in regions such as British Columbia (BC), Canada. We analyzed liver (n = 11) and skeletal muscle samples (n = 5) from 11 deceased sea otters from coastal BC using the U.S. Environmental Protection Agency method 1633 with ultrahigh performance liquid chromatography coupled to a triple quadrupole mass spectrometer. We found 8 of the 40 tested PFAS were present in all sampled sea otters, although concentrations of each PFAS varied between individuals. Sea otter livers contained more PFAS compounds at higher total average concentrations than skeletal muscle (i.e., 8 PFAS totaling 10.38 ng/g wet wt vs. 1 PFAS totaling 0.38 ng/g wet wt). Only perfluorooctanesulfonamide (PFOSA) was identified in both liver and muscle tissues, whereas the remaining 7 PFAS were unique to the liver. The three PFAS that dominated the liver PFAS composition (perfluorononanoic acid, PFOSA, and perfluorooctanesulfonic acid) accounted for 84% of the contaminant load in the livers. Geographically, PFAS concentrations were more than three times higher on average in sea otters recovered near major cities and shipping routes. Identifying the contaminants accumulating in sea otters provides insights into the health threats confronted by recovering sea otter populations. Our study also establishes baseline PFAS contamination levels in BC sea otters, which can be used to monitor and regulate the presence of PFAS on marine environments in western Canada.

Microplastic-derived dissolved organic matter (MP-DOM) has attracted widespread attention due to its adverse effects on ecological health. However, the dynamic formation of MP-DOM at the molecular level is not yet fully understood. Herein, the molecular level formation characteristics and mechanism of polyamide-MP-derived DOM (MPPA-DOM) during irradiation were explored using fluorescence spectroscopy. Fourier transform-ion cyclotron resonance mass spectrometry, and parallel factor analysis. The results showed that the time-dependent fluorescence signatures revealed a dominant tyrosine-like component, whose relative abundance increased from 49.63% to 89.62% during irradiation, suggesting a gradual accumulation of protein-related substances. Molecular element analyses of MPPA-DOM revealed the predominance of CHON molecules (78.82%-89.30%), which was attributed to the degradation of the C-N backbone structure. In contrast, CHO molecules exhibited a lower proportion (9.45%) under prolonged irradiation. Aliphatic/peptide-like compounds in MPPA-DOM remained the dominant component with a percentage range of 66.4% to 68.7%, whereas lignin-like compounds slightly increased with the increase of irradiation time. The reduced molecules were dominated in MPPA-DOM with a percentage range of 96.4% to 99.1%. As irradiation increased, the saturated compounds decreased from 91.53% to 82.45% and the unsaturated compounds increased from 7.6% to 14.1%. This study proposed a molecular-level formation mechanism of MPPA-DOM under irradiation. Nitrogen-rich molecules were persistent and highly stable during irradiation, indicating that they could play a more important role in the migration and transformation of MPPA-DOM. The findings in this study will provide support for assessing the potential ecological risks of MP-DOM in water systems.

Amphibians serve a central role in food webs and provide a link between aquatic and terrestrial habitats. Because of their dependence on water, amphibians are susceptible to legacy and emerging contaminants. We investigated mercury (Hg) and per- and polyfluoroalkyl substances (PFAS) concentrations in wild populations of two amphibian species-the green frog (Lithobates clamitans) and the American toad (Anaxyrus americanus)-which exhibit different life histories. We evaluated whether proximity to PFAS point source (State Superfund site) affected PFAS exposures in amphibians and assessed length, mass, sex, diet, and trophic position as predictors of contaminant concentrations. We found higher Hg concentrations in the more aquatic species (i.e., green frog) but higher PFAS concentrations (summed PFAS, perfluorodecanoic acid [PFDA], perfluoroundecanoic acid [PFUnA], perfluorododecanoic acid [PFDoA], perfluorotridecanoic acid [PFTrDA], and perfluorotetradecanoic acid [PFTeDA]) in the more terrestrial species (i.e., American toad). Proximity to the PFAS State Superfund site did not strongly affect PFAS exposures in amphibians. Of the biological predictors tested, diet best explained PFAS concentrations, but other factors (e.g., physiological differences) are likely contributing to the difference in PFAS bioaccumulation between aquatic and terrestrial species. Only three reports on PFAS concentrations in wild amphibians exist, all from contaminated sites in China, reporting much higher concentrations than found here. Additionally, experimental exposure studies have only investigated the effects of exposure to a few PFAS compounds, of which long-chain perfluoroalkyl carboxylic acids detected here (PFDA, PDUnA, PFDoA, PFTrDA, and PFTeDA) are not represented in the literature. To truly understand the effects that detectable PFAS impose on wild amphibians, research is needed on the effects of more PFAS compounds, bioaccumulation in larval and terrestrial amphibians, and the elimination of PFAS via their skin to different media.