Freshwater ecosystems are the main source of water for sustaining life on earth, and the biodiversity they support is the main source of valuable goods and services for human populations. Despite growing recognition of the impairment of freshwater ecosystems by micropollutant contamination, different conceptual and methodological considerations can newly be addressed to improve our understanding of the ecological impact into these ecosystems. Here, we originally combined in situ ecotoxicology and community ecology concepts to unveil the mechanisms structuring macroinvertebrate communities along a regional contamination gradient. The novelty of our study lies in the use of an innovative biomonitoring approach (measurement of metal contents in caged crustaceans) allowing to quantify and compare on a regional scale the levels of bioavailable metal contamination to which stream communities are exposed. We were hence able to identify 23 streams presenting a significant gradient of bioavailable metal contamination within the same catchment area in the South West of France, from which we also obtained data on the composition of resident macroinvertebrate communities. Analyses of structural and functional integrity of communities revealed an unexpected decoupling between taxonomic and functional diversity of communities in response to bioavailable metal contamination. We show that despite the negative impact of bioavailable metal contamination exposure on taxonomic diversity (with an average species loss of 17% in contaminated streams), functional diversity is maintained through a process of non-random species replacement by functional redundant species at the regional scale. Such unanticipated findings call for a deeper characterization of metal-tolerant communities’ ability to cope with environmental variability in multi-stressed ecosystems.

Arsenic (As) and copper (Cu) are common co-contaminates in soils. However, their interactive effects on their accumulation and distribution in As-hyperaccumulator Pteris vittata are poorly understood. A hydroponic experiment was conducted with As being 0, 5, or 50 μM and Cu being 0.32, 3.2, or 32 μM to evaluate their phytotoxicity, accumulation, and distribution in P. vittata. In addition, As and Cu uptake kinetics were examined using the Michaelis-Menten kinetics model. Total As and Cu concentrations in P. vittata were up to 487 and 1355 mg kg⁻¹. About 39–81% of the As was in the fronds compared to 0.6–18% for Cu. At 50 μM As, increasing Cu concentration from 0.32 to 32 μM increased root As while decreasing frond As concentrations, with the translocation factor (ratio of As in fronds to roots) being reduced from 4.0 to 0.31. In contrast, As did not affect Cu accumulation in P. vittata. Michaelis constant Kₘ value for As was higher than that of Cu (6.49–24.9 vs. 0.43–3.36), consistent with higher Cu uptake than As. Besides, Cu reduced root K but increased P levels in the roots, whereas As increased the K and P concentrations in the fronds. Our results suggest that P. vittata accumulated more Cu than As in the roots, contributing to its low As translocation. As such, high levels of Cu are likely to reduce As uptake by P. vittata during phytoremediation of As-contaminated sites.

The Sars-CoV-2 disease (known as COVID-19) has become a global public health emergency. Researchers have been unveiling the transmission mechanisms and disclosing possible contributing factors. Studies have theorized plausible linkage mechanisms between air pollution exposure and COVID-19 infection and have divided the air pollution exposure into two types: long-term exposure and short-term exposure. However, present studies on impacts of short-term exposure have not reached a conclusive result and are mostly focusing on Asian and European countries. In this study, we conduct a nationwide analysis to examine the association between short-term air pollution exposure and COVID-19 infection in the United States. Daily confirmed cases, air pollution information, and meteorological factors at the county level were collected between March 1st and June 30th, 2020. A total of 806 (out of 3143) counties were included in this study, with 554 counties for PM₂.₅ and 670 counties for ozone (O₃), which account for around 2.1 million cumulative confirmed cases, i.e., about 80% of all confirmed cases in the U.S. over the study period. A generalized additive model was applied to investigate the relationship between short-term exposure to PM₂.₅/O₃ and COVID-19 confirmed cases. The statistically significant results indicate that, with every 10 μg/m3 increase in mean pollutant concentration, the number of daily confirmed cases increases by 9.41% (CI: 8.77%–10.04%) for PM₂.₅ and by 2.42% (CI: 1.56%–3.28%) for O₃. The relative risks associated with short-term PM₂.₅ exposure remain positive after isolating the impacts of long-term exposure. The results of this study suggest that short-term exposure to air pollution, especially to PM₂.₅, may contribute to the spread and course of the pandemic. This finding has important implications for policymakers and the public to take preventive measures such as staying at home on polluted days while improving ventilation indoors to lower the probability of infection.

This study focused on the short-term whole organism bioassays (WOBs) on fish (Danio rerio) and crustaceans (Gammarus fossarum and Daphnia magna) to assess the negative biological effects of water from the major European River Sava and the comparison of the obtained results with in vitro toxicity data (ToxCast database) and Risk Quotient (RQ) methodology. Pollution profiles of five sampling sites along the River Sava were assessed by simultaneous chemical analysis of 562 organic contaminants (OCs) of which 476 were detected. At each sampling site, pharmaceuticals/illicit drugs category was mostly represented by their cumulative concentration, followed by categories industrial chemicals, pesticides and hormones. An exposure-activity ratio (EAR) approach based on ToxCast data highlighted steroidal anti-inflammatory drugs, antibiotics, antiepileptics/neuroleptics, industrial chemicals and hormones as compounds with the highest biological potential. Summed EAR-based prediction of toxicity showed a good correlation with the estimated toxicity of assessed sampling sites using WOBs. WOBs did not exhibit increased mortality but caused various sub-lethal biological responses that were dependant relative to the sampling site pollution intensity as well as species sensitivity. Exposure of G. fossarum and D. magna to river water-induced lower feeding rates increased GST activity and TBARS levels. Zebrafish D. rerio embryo exhibited a significant decrease in heartbeat rate, failure in pigmentation formation, as well as inhibition of ABC transporters. Nuclear receptor activation was indicated as the biological target of greatest concern based on the EAR approach. A combined approach of short-term WOBs, with a special emphasis on sub-lethal endpoints, and chemical characterization of water samples compared against in vitro toxicity data from the ToxCast database and RQs can provide a comprehensive insight into the negative effect of pollutants on aquatic organisms.

Survivorship of early life stages is key for the well-being of sea turtle populations, yet studies on animals that distribute around oceanic areas are very challenging. So far, the information on green turtles (Chelonia mydas) that use the open NE Atlantic as feeding grounds is scarce. Strandings occurring in oceanic archipelagos can provide relevant information about the biology, ecology and current anthropogenic pressures for megafauna inhabiting the open ocean. In this study, we analysed stranding events of green turtles found in the Azores archipelago to investigate interactions with marine litter. In addition, we quantified and characterized litter items stranded on beaches to provide a direct comparison between the ingested items with the debris found in the environment. A total of 21 juvenile green turtles were found stranded in the region between 2000 and 2020 (size range: 12–49 cm, CCL). Overall, 14% of the animals were entangled in marine litter and 86% of the turtles necropsied had ingested plastic. The mean abundance of items ingested was 27.86 ± 23.40 and 98% were white/transparent. Hard plastic fragments between 1 and 25 mm were the most common shape recovered in the turtles, similarly to what was found on the coastline. All of the litter items analysed with pyrolysis GC-MS revealed to be polyethylene (PE). This study provides the first baseline assessment of interactions of plastic litter with juvenile green turtles found at the east edge of the North Atlantic Subtropical Gyre. The combination of these results supports the hypothesis that migratory megafauna that use remote oceanic islands as a feeding ground are exposed to anthropogenic litter contamination dominated by plastics, even when these regions are located far away from big industrial centers or populated cities.

To improve the accuracy of dietary risk assessment of arsenic (As) from aquatic products, toxic As species (As(III), As(V), monomethylarsonic acid [MMA], and dimethylarsinic acid [DMA]) and total As were analyzed in 124 marketed aquatic products from eight coastal cities in China. Distribution characteristics of Toxic As (the sum of the four toxic As species) in the samples and associated risk of human dietary exposure were emphatically investigated. The impact of cooccurrence of As and other chemical elements in the aquatic products was assessed based on our former results of mercury (Hg) and selenium (Se). Toxic As contents (maximum value 0.358 mg kg⁻¹ wet weight) in the samples accounted for at most 14.1% of total As. DMA was the major component (mean proportion 50.8% for shellfish, 100% for fish) of Toxic As in aquatic products. Shellfish contained more Toxic As than fish did. Mean estimated daily intakes of Toxic As for the residents with aquatic product consumption rates of 46.1–235 g day⁻¹ ranged from 0.034 to 0.290 μg kg⁻¹ day⁻¹. Potential health risk was indicated among those who greatly consumed aquatic products, as their target hazard quotient (THQ) and target cancer risk (TR) values exceeded safety thresholds (1 for THQ, 10⁻⁴ for TR). DMA and MMA exposure contributed to 3.42–7.72% of the THQTₒₓᵢc Aₛ. Positive correlations between concentrations of As and Hg (Fish: r = 0.47, p < 0.01; Shellfish: r = 0.60, p < 0.01), as well as between that of As and Se (Fish: r = 0.69, p < 0.01; Shellfish: r = 0.37, p < 0.01) were found in the samples. It requires attentions urgently that As and Hg coexposure through aquatic product consumption rose the sum THQ of Toxic As and methylmercury (MeHg) to approximately two to eight times as high as the THQTₒₓᵢc Aₛ.

Industrial seabed mining is expected to cause significant impacts on marine ecosystems, including physical disturbance and the generation of plumes of toxin-laden water. Portmán Bay (NW Mediterranean Sea), where an estimated amount of 60 Mt of mine tailings from sulphide ores were dumped from 1957 to 1990, is one of the most metal-polluted marine areas in Europe and worldwide. This bay can be used to assess the impact on marine ecosystems of particle settling from sediment plumes resulting from mine tailings resuspension. With this purpose in mind, we conducted a field experiment there to investigate subsequent effects of deposition of (artificially resuspended) contaminated sediments on (i) prokaryotic abundance and meiofaunal assemblages (in terms of abundance and diversity), (ii) the availability of trophic resources (in terms of organic matter biochemical composition), and (iii) a set of ecosystem functions including meiofaunal biomass, heterotrophic C production and C degradation rates. The results of this study show that mine tailings resuspension and plume deposition led to the decline of prokaryotic abundance and nematode's biodiversity. The later decreased because of species removal and transfer along with particle resuspension and plume deposition. Such changes were also associated to a decrease of the proteins content in the sediment organic matter, faster C degradation rates and higher prokaryotic C production. Overall, this study highlights that mine tailing resuspension and ensuing particle deposition can have deleterious effects on both prokaryotes and nematode diversity, alter biogeochemical cycles and accelerate C degradation rates. These results should be considered for the assessment of the potential effects of seabed mineral exploitation on marine ecosystems at large.

Graphene oxide (GO) has been widely studied and applied in numerous industrial fields and biomedical fields for its excellent physical and chemical properties. Along with the production and applications of GO persist increasing, the environmental health and safety risk (EHS) of GO has been widely studied. However, previous studies almost focused on the biotoxicity of pristine GO under a relatively high exposure dose, without considering its transformation process within environmental and biological mediums. Meanwhile, its secondary toxicity or synergistic effects have not been taken seriously. Here, two different kinds of artificial lung fluids were adopted to incubate pristine GO to mimic the biotransformation process of GO in the lung fluids. And, we explored that biotransformation within the artificial lung fluids could significantly change the physicochemical properties of GO and could enhance its biotoxicity. To reveal the synergistic effects of GO and toxic metal ions, we uncovered that GO could enhance the intracellular content of metal ions by inhibiting the efflux function of ATP binding cassette (ABC) transporters which are distributed on the cellular membrane, and artificial lung fluids incubation of GO could enhance this synergistic effect. Finally, toxic metal ions induced a series of toxic reactions through oxidative stress response and promoted cell death. Moreover, consistent with the results of in vitro experiments, the lungs of mice exposed to GOs combined with Cd exhibited significant inflammation and oxidative stress compared with Cd treatment alone, and it was more remarkable within the mice which were treated with bio-transformed GOs. In summary, this study explored the impact and mechanism of biotransformation of GO in the lung fluids on the synergistic and secondary effects between GO and metal ions.

A recently identified chemical, 2-((4-Methylpentan-2-yl)amino)-5-(phenylamino)cyclohexa-2,5-diene-1,4-dione (6PPD-quinone; 6PPD-Q), is a transformation product of an additive used in the manufacture of tire rubber and causes acute lethality in coho salmon (Oncorhynchus kisutch) in urban watersheds. Despite its potential presence and ecotoxicity in receiving waters worldwide, information on the occurrence and fate of 6PPD-Q is limited. Here, we investigated the concentrations of 6PPD-Q and its parent chemical, 6PPD, in road dust collected from arterial and residential roads in Tokyo, Japan from May to October 2021. 6PPD-Q concentrations were highest from May to June, when atmospheric ozone concentrations are the highest in Japan; a correlation between 6PPD-Q and photochemical oxidants, as an alternative to ozone, corroborated this finding. We also found that 6PPD-Q concentrations at photochemical oxidant concentrations ranging from 35 to 47 ppbv were higher in dust collected from roads with high traffic volumes (i.e., arterial roads; median: 8.6 μg/g-OC) than in dust collected from roads with lower traffic volumes (i.e., residential roads; median: 6.3 μg/g-OC), indicating that 6PPD-Q is generated from traffic-related sources. We also found that 6PPD-Q was leached from dust particles within a few hours, with a log partitioning coefficient between organic carbon and water (KOC) of 3.2–3.5. The present results will help to understand the environmental occurrence, fate, and behavior of 6PPD-Q.

China is the largest beekeeping and honey consumption country globally. Neonicotinoids in honey can pose adverse effects on honey bees and human, but data on neonicotinoids residues in honey and its health risk remain limited in China. A total of 94 honey samples were selected from Chinese market based on production region and sale volume in 2020. Eight neonicotinoids and four metabolites were determined by liquid chromatography coupled to mass spectrometry. Health risk of neonicotinoids in honey on honey bees and human was assessed by hazard quotient (HQ) and hazard index (HI). Neonicotinoids and their metabolites were overall detected in 97.9% of honey samples. Acetamiprid, thiamethoxam, and imidacloprid were top three dominant neonicotinoids in honey with the detection frequencies of 92.6%, 90.4%, and 73.4%, respectively. For honey bees, 78.7% of honey samples had a HI larger than one based on the safety threshold value of sublethal effects. Top three neonicotinoids with the highest percent proportion of HQ larger than one for honey bees were acetamiprid (43.6%), imidacloprid (31.9%), and thiamethoxam (24.5%) and their maximum HQs were 420, 210, and 41, respectively. Based on oral median lethal doses for honey bees, both HQ and HI were lower than one in all honey samples. For human, both HQ and HI were lower than one based on acceptable daily intakes in all honey samples. Neonicotinoids concentrations and detection frequencies in honey samples and its health risk varied with production region, commercial value of nectariferous plants, number of nectariferous plants, and sale price. The results suggested extensive residues of neonicotinoids in honey in Chinese market with a variation by the characteristics of honey. The residues were likely to affect the health of honey bees, but showed no detectable effect on human health.