Plant-endophyte synergism has been demonstrated to play a key role in the phytoremediation of contaminated water and soil. Phytoalexins, a type of chemical component in the plant apoplast, can be produced by plants in response to stimulation by endophytes. Phytoalexins may have distinct effects on the nutritional and metabolic functions of endophytes; however, direct evidence is not available to prove the effect of phytoalexins on the hydrophobic organic contaminants (HOC)-degradation activity of endophytes. In this paper, three different types of phytoalexins, coumarin, resveratrol and rutin, were selected to study their effect on the removal of polycyclic aromatic hydrocarbons (PAHs) by an endophytic bacterium Methylobacterium extorquens C1. The effects of the three phytoalexins on bacterial sorption and intracellular enzymatic activities were tested to further analyze the mechanism by which the phytoalexins affect the PAH degradation performance of M. extorquens C1. The results showed that the removal rate of PAHs by M. extorquens C1 increased in the presence of low levels of the three phytoalexins. The most effective concentrations of coumarin, resveratrol and rutin were 0.20, 0.15, and 0.25 mg/L, respectively, and the removal rate of PAHs was increased by approximately 18.3–35.0%. At the optimal concentrations, the three phytoalexins significantly promoted the sorption of PAHs by M. extorquens C1, and also enhanced the activities of catechol dioxygenases and dehydrogenase of M. extorquens C1. The positive effect of phytoalexins on both bacterial sorption and intracellular enzymatic activities promotes the overall removal of PAHs from endophytes. These results may deepen our understanding of plant-microbe cooperative mechanisms in the degradation of organic pollutants and provide a new approach for chemically enhanced bioremediation in the future.

The issue of potential long-term or hereditary effects for both humans and wildlife exposed to low doses (or dose rates) of ionising radiation is a major concern. Chronic exposure to ionising radiation, defined as an exposure over a large fraction of the organism's lifespan or even over several generations, can possibly have consequences in the progeny. Recent work has begun to show that epigenetics plays an important role in adaptation of organisms challenged to environmental stimulae. Changes to so-called epigenetic marks such as histone modifications, DNA methylation and non-coding RNAs result in altered transcriptomes and proteomes, without directly changing the DNA sequence. Moreover, some of these environmentally-induced epigenetic changes tend to persist over generations, and thus, epigenetic modifications are regarded as the conduits for environmental influence on the genome.Here, we review the current knowledge of possible involvement of epigenetics in the cascade of responses resulting from environmental exposure to ionising radiation. In addition, from a comparison of lab and field obtained data, we investigate evidence on radiation-induced changes in the epigenome and in particular the total or locus specific levels of DNA methylation. The challenges for future research and possible use of changes as an early warning (biomarker) of radiosensitivity and individual exposure is discussed. Such a biomarker could be used to detect and better understand the mechanisms of toxic action and inter/intra-species susceptibility to radiation within an environmental risk assessment and management context.

Toxicity of hazard materials to organism is different between larvae and adult zebrafish. However, this different effect was seldom considered in toxicological modeling. Here, we measured Cd and Pb toxicity for larvae and adult zebrafish (Danio rerio) and assessed whether metal toxicity can be better simulated by the one-compartment or two-compartment toxicokinetic (TK) and toxicodynamic (TD) models with assumption of stochastic death (SD) and individual tolerance (IT), respectively. Results showed that, for larvae, the one-compartment model generally fitted the observed accumulation and survival better than two-compartment model. In contrast, for adult, the two-compartment model simulation satisfied the observed accumulation and survival better than one-compartment model. In addition, both the SD and the IT models generally described the Cd or Pb toxicity well, although the IT model predictions were slightly better than the SD model in adult fish, the opposite phenomenon was observed in larvae. Our results suggested that variations in both TK and TD parameters might be needed to quantify the toxicity sensitivity in larvae and adult zebrafish, and accounting these variations in mechanistic toxicological effect models (e.g. TK-TD) will allow more accurate predictions of hazard materials effects to organisms.

Arsenic (As) present in water is a nonignorable environmental issue, even at low concentrations (≤150 μg L⁻¹). To evaluate the toxic effect of low concentrations of As, zebrafish at early life stage were exposed to 0, 25, 50, 75, or 150 μg L⁻¹ AsIII for 120 h. Our results indicated that low concentration of AsIII decreased zebrafish larvae’s survival rate to 85%, 89% and 86% at 50, 75 and 150 μg L⁻¹. Furthermore, low concentrations of AsIII exposure caused oxidative stress (elevated superoxide dismutase (SOD) activity and influenced the mRNA transcriptional levels of Cu/ZnSOD and MnSOD) and damage (increased malondialdehyde levels). Meanwhile, zebrafish larvae regulated the mRNA transcription of metallothionein and heat shock protein 70 to alleviate toxicity caused by AsIII. These results revealed lower concentrations (≤150 μg L⁻¹) of AsIII had a detriment effect on the survival of fish at early life stage, moreover, oxidative stress caused by AsIII posed potential risk for the zebrafish. This study provides novel insight into low concentration AsIII-induced toxicity in zebrafish.

Despite substantial mitigation of particulate matter (PM) pollution during the past decade in Beijing, the response of aerosol chemistry to clean air action and meteorology remains less understood. Here we characterized the changes in aerosol composition as responses to emission reductions by using two-year long-term measurements in 2011/2012 and 2017/2018, and WRF-Chem model. Our results showed substantial decreases for all aerosol species except nitrate from 2011/2012 to 2017/2018. Chloride exhibited the largest decrease by 65–89% followed by organics (37–70%), mainly due to reductions in coal combustion emissions in winter and agriculture burning in June. Primary and secondary organic aerosol (SOA) showed comparable decreases by 61–70% in fall and winter, and 34–63% in spring and summer, suggesting that reductions in primary emissions might also suppress SOA formation. The changes in nitrate were negligible and even showed increases due to less reductions in NOₓ emissions and increased formation potential from N₂O₅ heterogeneous reactions. As a result, nitrate exceeded sulfate and became the major secondary inorganic aerosol species in PM with the contribution increasing from 14–21% to 22–32%. Further analysis indicated that the reductions in aerosol species from 2011/2012 to 2017/2018 were mainly caused by the decreases of severely polluted events (PM₁ > 100 μg m⁻³). WRF-Chem simulations suggested that the decreases in OA and sulfate in fall and winter were mainly resulted from emission reductions (27–36% and 25–43%) and favorable meteorology (4–10% and 19–30%), while they were dominantly contributed by emission changes in spring and summer. Comparatively, the changes in nitrate were mainly associated with meteorological variations while the contributions of emissions changes were relatively small. Our results highlight different chemical responses of aerosol species to emission changes and meteorology, suggesting that future mitigation of air pollution in China needs species-targeted control policy.

Previous in vitro studies have implied that triphenyl phosphate (TPHP) may act as an obesogen. However, its specific contributions to the progression of obesity and related metabolic diseases are still unclear in vivo in mice. In this study, we evaluated the effects of in utero and lactational exposure to three doses of TPHP (10, 100, and 1000 μg/kg BW) on obesity and metabolic dysfunctions in adult male mice fed a low-fat diet (LFD) or high-fat diet (HFD), by examining body weight, liver weight, histopathology, blood biochemistry, gene expression, and gut microbiota compositions and metabolic functions. Results showed that TPHP exposure led to increased body weight, liver weight, fat mass, hepatic steatosis, impaired glucose homeostasis, and insulin resistance, and mRNA levels of genes involved in lipid metabolism, especially lipogenesis and lipid accumulation, were significantly altered by TPHP treatment. Gas chromatography-mass spectrometry (GC-MS) analysis further supported the changes in fatty acid composition. Intestinal flora measurements by 16S rRNA gene sequencing and ¹H NMR based fecal metabolomics indicated that TPHP treatment modulated gut microbiome composition and influenced host-gut co-metabolism, especially for bile acids and short chain fatty acids (SCFAs). These results suggest that fetal exposure to TPHP can promote the development of obesity and metabolic dysfunctions in adult mice.

Aircraft soot has a significant impact on global and local air pollution and is of particular concern for the population working at airports and living nearby. The morphology and chemistry of soot are related to its reactivity and depend mainly on engine operating conditions and fuel-type. We investigated the morphology (by transmission electron microscopy) and chemistry (by X-ray micro-spectroscopy) of soot from the exhaust of a CFM 56-7B26 turbofan engine, currently the most common engine in aviation fleet, operated in the test cell of SR Technics, Zurich airport. Standard kerosene (Jet A-1) and a biofuel blend (Jet A-1 with 32% HEFA) were used at ground idle and climb-out engine thrust, as these conditions highly influence air quality at airport areas. The results indicate that soot reactivity decreases from ground idle to climb-out conditions for both fuel types. Nearly one third of the primary soot particles generated by the blended fuel at climb-out engine thrust bear an outer amorphous shell implying higher reactivity. This characteristic referring to soot reactivity needs to be taken into account when evaluating the advantage of HEFA blending at high engine thrust. The soot type that is most prone to react with its surrounding is generated by Jet A-1 fuel at ground idle. Biofuel blending slightly lowers soot reactivity at ground idle but does the opposite at climb-out conditions. As far as soot reactivity is concerned, biofuels can prove beneficial for airports where ground idle is a common situation; the benefit of biofuels for climb-out conditions is uncertain.

In standard terrestrial ecotoxicological tests, soils usually are spiked with highly soluble metal salts leading to overestimation of bioavailability and introducing counterions that may contribute to toxicity. Leaching is suggested as an efficient method to avoid the effects of the associated counterions. The present study aimed at investigating the effects of leaching on the bioavailability and toxicity of Pb(NO₃)₂ and PbO to the potworm Enchytraeus crypticus in LUFA 2.2 soil freshly spiked or after 18 months ageing. Percolation decreased porewater Pb concentrations as well as the toxicity of both Pb forms. The influence of percolation differed between the two Pb forms and between freshly spiked and aged soils. Percolation slightly increased LC50s based on total soil Pb concentrations for Pb(NO₃)₂, but not for PbO, and only affected Pb toxicity to enchytraeid reproduction in freshly spiked soils. The differences in Pb uptake in E. crypticus and toxicity between the two Pb forms as well as between different treatments could be minimized by relating them to 0.01 M CaCl₂-extractable concentrations. In addition, body Pb concentrations could well explain enchytraeid survival across all soils and treatments, indicating its suitability as a good proxy for Pb toxicity in soil.

Carbonaceous aerosols (CAs) scatter and absorb incident solar radiation in the atmosphere, thereby influencing the regional climate and hydrological cycle, particularly in the Third Pole (TP). Here, we present the characteristics of CAs at 19 observation stations from the Atmospheric Pollution and Cryospheric Change network to obtain a deep understanding of pollutant status in the TP. The organic carbon (OC) and elemental carbon (EC) concentrations decreased noticeably inwards from outside to inland of the TP, consistent with their emission load and also affected by transport process and meteorological condition. Urban areas, such as Kathmandu, Karachi, and Mardan, exhibited extremely high OC and EC concentrations, with low and high values occurring in the monsoon and non-monsoon seasons, respectively. However, remote regions inland the TP (e.g., Nam Co and Ngari) demonstrated much lower OC and EC concentrations. Different seasonal variations were observed between the southern and northern parts of the TP, suggesting differences in the patterns of pollutant sources and in distance from the sources between the two regions. In addition to the influence of long-range transported pollutants from the Indo-Gangetic Plain (IGP), the TP was affected by local emissions (e.g., biomass burning). The OC/EC ratio also suggested that biomass burning was prevalent in the center TP, whereas the marginal sites (e.g., Jomsom, Dhunche, and Laohugou) were affected by fossil fuel combustion from the up-wind regions. The mass absorption cross-section of EC (MACEC) at 632 nm ranged from 6.56 to 14.7 m² g⁻¹, with an increasing trend from outside to inland of the TP. Urban areas had low MACEC values because such regions were mainly affected by local fresh emissions. In addition, large amount of brown carbon can decrease the MACEC values in cities of South Asia. Remote sites had high MACEC values because of the coating enhancement of aerosols.Influenced by emission, transport process, and weather condition, the CA concentrations and MACEC presented decreasing and increasing trends, respectively, from outside to inland of the TP.

Sublethal insecticide exposure poses risks for many non-target organisms and is a challenge for successful implementation of integrated pest management (IPM) programs. Next to detrimental effects of short-term insecticide exposure on fitness-related traits of organisms, also properties such as chemical signaling traits can be altered, which mediate intra- and interspecific communication. We investigated the effects of different durations of larval sublethal exposure to the pyrethroid lambda-cyhalothrin on performance traits of larvae and adults of the herbivorous mustard leaf beetle, Phaedon cochleariae. Moreover, by applying a direct contact and olfactometer bioassays, we determined the reaction of a generalist predator, the ant Myrmica rubra, towards insecticide-exposed and unexposed herbivore larvae and their secretions. Already short-term sublethal insecticide exposure of a few days caused a prolonged larval development and a reduced adult body mass of males. These effects may result from an insecticide-induced reduction in energy reserves. Furthermore, ants responded more frequently to insecticide-exposed than to unexposed larvae of P. cochleariae and their secretions. This increased responsiveness of ants towards insecticide-exposed larvae may be due to an insecticide-induced change in synthesis of chrysomelidial and epichrysomelidial, the dominant compounds of the larval secretion, which act defensive against various generalist predators. In conclusion, the results highlight that short-term insecticide exposure can impair the fitness of an herbivorous species due to both direct toxic effects and an increased responsiveness of predators. Consequently, exposure of single non-target species can have consequences for ecological communities in both natural habitats and IPM programs.