Road transport is the main anthropogenic source of NOx in Europe, affecting human health and ecosystems. Thus, mitigation policies have been implemented to reduce on-road vehicle emissions, particularly through the Euro standard limits. To evaluate the effectiveness of these policies, we calculated NO₂ and NOx concentration trends using air quality and meteorological measurements conducted in three European cities over 26 years. These data were also employed to estimate the trends in NOx emission factors (EFNOₓ, based on inverse dispersion modeling) and NO₂:NOx emission ratios for the vehicle fleets under real-world driving conditions. In the period 1998–2017, Copenhagen and Stockholm showed large reductions in both the urban background NOx concentrations (−2.1 and −2.6% yr⁻¹, respectively) and EFNOₓ at curbside sites (68 and 43%, respectively), proving the success of the Euro standards in diminishing NOx emissions. London presented a modest decrease in urban background NOx concentrations (−1.3% yr⁻¹), while EFNOₓ remained rather constant at the curbside site (Marylebone Road) due to the increase in public bus traffic. NO₂ primary emissions —that are not regulated— increased until 2008–2010, which also reflected in the ambient concentrations. This increase was associated with a strong dieselization process and the introduction of new after-treatment technologies that targeted the emission reduction of other species (e.g., greenhouse gases or particulate matter). Thus, while regulations on ambient concentrations of specific species have positive effects on human health, the overall outcomes should be considered before widely adopting them. Emission inventories for the on-road transportation sector should include EFNOₓ derived from real-world measurements, particularly in urban settings.

Mites are considered the worst enemy of honey bees, resulting in economic losses in agricultural production. In apiculture, flumethrin is frequently used to control mites. It causes residues of flumethrin in colonies which may threaten honey bees, especially for larvae. Still, the impact of flumethrin-induced dysbiosis on honey bees larval health has not been fully elucidated, and any impact of microbiota for decomposing flumethrin in honey bees is also poorly understood. In this study, 2-day-old larvae were fed with different flumethrin-sucrose solutions (0, 0.5, 5, 50 mg/kg) and the dose increased daily (1.5, 2, 2.5 and 3 μL) until capped, thereafter the expression level of two immune genes (hymenoptaecin, defensin1) and two detoxication-related genes (GST, catalase) were measured. Meanwhile, the effect of flumethrin on honey bee larvae (Apis mellifera) gut microbes was also explored via 16S rRNA Illumina deep sequencing. We found that flumethrin at 5 mg/kg triggered the over expression of immune-related genes in larvae, while the larval detoxification-related genes were up-regulated when the concentrations reached 50 mg/kg. Moreover, the abundance and diversity of microbes in flumethrin-treated groups (over 0.5 mg/kg) were significantly lower than control group, but it increased with flumethrin concentrations among the flumethrin-treated groups. Our results revealed that microbes served as a barrier in the honey bee gut and were able to protect honey bee larvae to a certain extent, and reduce the stress of flumethrin on honey bee larvae. In addition, as the concentration of flumethrin increases, honey bee larvae activate their immune system then detoxification system to defend against the potential threat of flumethrin. This is the first report on the impact of flumethrin on gut microbiota in honey bees larvae. The findings revealed new fundamental insights regarding immune and detoxification of host-associated microbiota.

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.

Potentially toxic Cylindrospermopsis raciborskii blooms are of emerging concerns, as its scale is spreading from tropical regions to high latitudes, increasing the risk of aquatic biota being exposed to cylindrospermopsin (CYN). So far, CYN-producing C. raciborskii strains have only been reported in tropical waters which are commonly phosphorus (P)-deficient, where they can dominate phytoplankton communities. However, the influence of CYN on phytoplankton communities under different P status remains unclear. In this study, we first analyzed the summer observations of 120 tropical reservoirs in Guangdong Province. The proportion of potential CYN-producers was significantly higher in P-deficient and CYN-present reservoirs than that in P-sufficient or CYN-absent ones. This suggested that in P-deficient condition, the potential CYN producers might gain more advantages by the help of CYN. Then, in laboratory experiments we found that upon P deprivation, CYN did not inhibit the cell growth of other algal cells, but significantly stimulates them to secret more alkaline phosphatase (ALP) than in P-sufficient condition. Through transcriptomics, we further revealed that under such P-deficient condition, CYN remarkably induced intracellular nitrogen allocation and protein export system by activating the PIK3/Akt-cGMP/PKG signaling pathways in Scenedesmus bijugatus, thus enhancing its ALP secretion. Our study implies that CYN-induced ALP secretion is facilitated upon P deficiency, thus supporting the dominance of its producers C. raciborskii.

Since early 2020, the world has faced an unprecedented pandemic caused by the novel COVID-19 virus. In this study, we characterize the impact of the lockdown associated with the pandemic on air quality in six major cities across the state of Florida, namely: Jacksonville, Tallahassee, Gainesville, Orlando, Tampa, and Miami. Hourly measurements of PM₂.₅, ozone, NO₂, SO₂, and CO were provided by the US EPA at thirty sites operated by the Florida Department of Environmental Protection during mid-February to mid-April from 2015 through 2020. To analyze the effect of the pandemic, atmospheric pollutant concentrations in 2020 were compared to historic data at these cities during the same period from 2015 to 2019. Reductions in NO₂ and CO levels were observed across the state in most cities and were attributed to restrictions in mobility and the decrease in vehicle usage amid the lockdown. Likewise, decreases in O₃ concentrations were observed and were related to the prevailing NOₓ-limited regime during this time period. Changes in concentrations of SO₂ exhibited spatial variations, concentrations decreased in northern cities, however an increase was observed in central and southern cities, likely due to increased power generation at facilities primarily in the central and southern regions of the state. PM₂.₅ levels varied temporally during the study and were positively correlated with SO₂ concentrations during the lockdown. In March, reductions in PM₂.₅ levels were observed, however elevations in PM₂.₅ concentrations in April were attributed to long-range transport of pollutants rather than local emissions. This study provides further insight into the impacts of the COVID-19 pandemic on anthropogenic sources from vehicular emissions and power generation in Florida. This work has implications for policies and regulations of vehicular emissions as well as consequences on the use of sustainable energy sources in the state.

Because most relevant studies have used small sample sizes, to date, representative atmospheric monitoring of persistent organic pollutants (POPs) on a regional scale has been very limited, which makes it difficult to precisely identify “hotspots” and possible pollution sources. In this study, an ultrahigh resolution monitoring technique was used to measure the atmospheric spatial variations in POP concentrations on a regional scale, throughout Campania, Italy. The occurrence of specific POPs—including polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polycyclic aromatic hydrocarbons (PAHs), polybrominated diphenyl ethers (PBDEs) and phthalate esters (PAEs)—were investigated using polyurethane foam-based passive air samplers (PUF-PAS), which were deployed at 129 sites across the Campania Territory between April and July 2016. The results show that the highest POP levels occurred in the Naples metropolitan area (NMA), although there were other problematic spots throughout the Territory. More specifically, hotspot areas in the NMA that depict serious POP pollution were found in the Bagnoli brownfield site, Sarno River Basin, and parts of the northeastern NMA sector. The atmospheric POP contamination in Campania is jointly controlled by the contributions of local emissions and long-range atmospheric transport. Diffusion model was employed to identify the potential sources of various POPs. The simulation showed that all the POP sources are located in the NMA and are closely related to industrial sites. This study demonstrates the advantage of using large sample sizes to identify POP source locations and achieve geospatial visualization of POP concentration and risk assessment levels.

Research on the relationship between short-term exposure to fine particulate matter (PM₂.₅) and urinary metabolites of polycyclic aromatic hydrocarbons (PAHs) is sparse in the nonoccupationally exposed populations. A quasi-experimental observation of haze events nested within a randomized crossover trial of alternative 1-week real or sham indoor air filtration was conducted to evaluate the associations of urinary monohydroxy-PAHs (OH-PAHs) with short-term exposure to PM₂.₅ and PM₂.₅-bound PAHs. The study was conducted among 57 healthy college students in Beijing, China. PM₂.₅-bound PAHs and urinary OH-PAHs were quantified using gas chromatography coupled with a triple-quadrupole tandem mass spectrometer. Linear mixed-effect models were applied to evaluate the association of urinary OH-PAHs with time-weighted personal PM₂.₅ and PM₂.₅-bound PAHs, controlling for potentially confounding variables. The results demonstrated that air filtration could markedly reduce external exposure to PM₂.₅ and PM₂.₅-bound parent, nitrated, and oxygenated PAHs. In the intervention trial, the urinary concentrations of 2-hydroxyfluorene (2-OH-FLU) and 9-hydroxyphenanthrene (9-OH-PHE) were elevated significantly by 16.5% (95% CI, 2.1%, 33.1%) and 37.9% (95% CI, 8.4%, 75.4%), respectively, in association with a doubling increase in personal PM₂.₅ exposure. Urinary 9-OH-PHE was also significantly positively associated with the increase in the sum of PM₂.₅-bound parent PAHs. Furthermore, the levels of urinary OH-PAHs such as 2-OH-FLU and 9-OH-PHE in the haze events were elevated by 31.1% (95% CI, 8.7%, 53.4%) and 73.5% (95% CI, 16.0%, 131.0%), respectively, in association with a doubling increase in personal PM₂.₅ exposure. The findings indicated that urinary 2-OH-FLU and 9-OH-PHE could serve as potential internal exposure biomarkers for assessing short-term PM₂.₅ exposure in nonoccupational populations.

Hydrogen peroxide (H₂O₂), as a common disinfectant, has been extensively used in aquaculture. The toxicity of high ambient H₂O₂ for gills and liver of fish has received attention from many researchers. However, whether H₂O₂ exposure induced brain injury and neurotoxicity has not been reported in fish. Therefore, this study aimed to explore the potential mechanism of H₂O₂ toxicity in brain of common carp via transcriptome analysis and biochemical parameter detection. The fish were exposed to 0 (control) and 1 mM of H₂O₂ for 1 h per day lasting 14 days. The results showed that H₂O₂ exposure caused oxidative damage in brain evidenced by decreased glutathione (GSH), total antioxidant capacity (T-AOC) and nicotinamide adenine dinucleotide (NAD⁺) levels, and increased formation of malondialdehyde (MDA) and 8-hydroxy-2′-deoxyguanosine (8-OHdG). Meanwhile, H₂O₂ exposure reduced 5-hydroxytryptamine (5-HT) level, and down-regulated tryptophan hydroxylase 1 (tph1a), tph2, 5-hydroxytryptamine receptor 1A-beta (htr1ab) and htr2b expression in brain. Transcriptome analysis showed that H₂O₂ exposure up-regulated 604 genes and down-regulated 1209 genes in brain. Go enrichment displayed that the differently expressed genes (DEGs) were enriched mainly in cellular process, single-organism process, metabolic process, and biological regulation in the biological process category. Further, KEGG enrichment indicated that H₂O₂ exposure led to dysregulation of neurotransmitter signals including depression of glutamatergic synapse, GABAergic synapse and endocannabinoid signaling. Also, we found the alteration of three key pathways including calcium, cAMP and HIF-1 in brain after H₂O₂ exposure. In conclusion, our data indicated that H₂O₂ exposure induced oxidative damage and neurotoxicity, possibly related to dysregulation of neurotransmitters and calcium, cAMP and HIF-1 signaling pathways, which may adversely affect learning, memory and social responses of common carp. This study provided novel insight into biological effects and underlying mechanism of H₂O₂ toxicity in aquatic animal, and contributed to proper application of H₂O₂ in aquaculture.

Phthalates (PAEs) are popular synthetic chemicals used as plasticizers and solvents for various products, such as polyvinyl chloride or personal care products. Human exposure to PAEs is associated with various diseases, resulting in PAE biomonitoring in humans. Inhalation, dietary ingestion, and dermal absorption are the major human exposure routes. However, estimating the actual exposure dose of PAEs via an external route is difficult. As a result, estimation by internal exposure has become the popular analytical methods to determine the concentrations of phthalate metabolites (mPAEs) in human matrices (such as urine, serum, breast milk, hair, and nails). The various exposure sources and patterns result in different composition profiles of PAEs in biomatrices, which vary from country to country. Nevertheless, the mPAEs of diethyl phthalate (DEP), di-n-butyl phthalate (DnBP), di-iso-butyl phthalate (DiBP), and di-(2-ethylhexyl) phthalate (DEHP) are predominant in the urine. These mPAEs have greater potential health risks for humans. Children have been observed to exhibit higher exposure risks to several mPAEs than adults. Besides age, other influencing factors for phthalate exposure are gender, jobs, and residential areas. Although many studies have reported biological monitoring of PAEs, only a few reviews that adequately summarized the reports are available. The current review appraised available studies on mPAE quantitation in human biomatrices and estimated the dose and health risks of phthalate exposure. While some countries lack biomonitoring data, some countries’ data do not reflect the current PAE exposure. Thence, future studies should involve frequent PAE biomonitoring to accurately estimate human exposure to PAEs, which will contribute to health risk assessments of human exposure to PAEs. Such would aid the formulation of corresponding regulations and restrictions by the government.

Previous studies of perfluorinated alkyl substances (PFASs) in receiving water bodies of typical industrial parks under the low-carbon development mode are scarce. In the present study, 18 PFASs were analyzed in surface water and sediment samples of the inland river basin in Longgang District in 2017. The ΣPFAS concentrations in surface water (drought and rainy periods) and sediment ranged from 15.17 to 948.50 ng/L, 11.56–561.14 ng/L, and 1.07–28.94 ng/g dw, respectively. Perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA) and perfluorobutane sulfonate (PFBS) were the dominant pollutants in surface water, with maximum concentrations of 867.68 ng/L, 288.28 ng/L, and 245.09 ng/L, respectively. Meanwhile, PFOS, perfluoroundecanoic acid (PFUdA), PFBS, and perfluorodecanoic acid (PFDA) were the major PFASs in the sediment samples, with maximum concentrations of 9.83 ng/g dw, 11.86 ng/g dw, 5.30 ng/g dw, and 5.23 ng/g dw, respectively. In addition, PFOA and PFOS resulted from similar sources in sediment and surface water samples (P < 0.05). The risk quotient value (RQ) results showed that the control of PFOS in the treatment of pollutants in the inland river basin of Longgang District deserves more attention.