Ground-level ozone (O3) concentrations have been elevating in the last century. While there has been a notable progress in understanding O3 effects on vegetation, O3 effects on ecological stoichiometry remain unclear, especially early in the oxidative stress. Ethyelenediurea (EDU) is a chemical compound widely applied in research projects as protectant of plants against O3 injury, however its mode of action remains unclear. To investigate O3 and EDU effects early in the stress, we sprayed willow (Salix sachalinensis) plants with 0, 200 or 400 mg EDU L−1, and exposed them to either low ambient O3 (AOZ) or elevated O3 (EOZ) levels during the daytime, for about one month, in a free air O3 controlled exposure (FACE); EDU treatment was repeated every nine days. We collected samples for analyses from basal, top, and shed leaves, before leaves develop visible O3 symptoms. We found that O3 altered the ecological stoichiometry, including impacts in nutrient resorption efficiency, early in the stress. The relation between P content and Fe content seemed to have a critical role in maintaining homeostasis in an effort to prevent O3-induced damage. Photosynthetic pigments and P content appeared to play an important role in EDU mode of action. This study provides novel insights on the stress biology which are of ecological and toxicological importance.

Microcystin-LR (MC-LR) is the most abundant toxicant among microcystin variants produced by cyanobacteria. MC-induced toxicity is broadly reported to pose a threat to aquatic animals and humans and has been associated with the dysfunction of some organs such as liver and kidney. However, MC-induced neurotoxicity has not been well characterized after long-term exposure. This study was designed to investigate the neurotoxic effects after chronic oral administration of MC-LR. In our trial, C57/BL6 mice received MC-LR at 0, 1, 5, 10, 20 and 40 μg/L in drinking water for twelve months. Our data demonstrated that mitochondrial DNA (mtDNA) damage was evident in the damaged neurons as a result of chronic exposure. Histopathological abnormalities and mtDNA damage were observed in the hippocampus and cerebral cortex. Furthermore, MC-LR exerted distinct effects on these two brain regions. The hippocampus was more susceptible to the treatment of MC-LR compared with the cerebral cortex. However, no strong relationships were observed between the genotoxic effects and exposure doses. In conclusion, this study has provided a mtDNA-related mechanism for underlying chronic neurotoxicity of MC-LR and suggested the presence of differential toxicant effects on the hippocampus and cerebral cortex.

Plants have the ability to adapt themselves under stressed conditions through reprogramming their growth and development. Understanding the mechanisms regulating overall growth of stressed plant is an important issue for plant and environmental biology research. Although the role of NO in modulating arsenic (As) toxicity is known, nitric oxide (NO) induced alteration in auxin and nutrient related transporters during As stress in rice is poorly understood. Experimental results showed that As exposure decreased gene expression level of polar auxin transporter (PIN proteins), and nutrient transporter related genes (AMT, NRT, NiR, PHT, KTP). The improved tolerance induced by As + NO combination is attributed to reduced As accumulation in rice seedlings, improved root architectural changes, overall growth of plant, chlorophyll, protein content, and accumulation of mineral nutrients by reducing the ROS generation. Further, enhanced transcript levels of PIN proteins and mineral nutrition related genes were also observed under As + NO treatment. Additional biochemical data revealed enhanced oxidative stress by increasing the level of antioxidant enzymes, and stress-related parameters. Overall, the study provides an integrated view of plant response during As + NO interaction to change the plant metabolism through different cellular processes.

Microplastics may lose buoyancy and occur in deeper waters and ultimately sink to the sediment and this may threaten plankton inhabiting in various water layers and benthic organisms. Here, we conduct the first survey on microplastics in the water column and corresponding sediment in addition to the surface water in the Bohai Sea. A total of 20 stations covering whole Bohai Sea were selected, which included 6 stations specified for water column studying. Seawater was sampled every 5 m, with maximal depth of 30 m in the water column using Niskin bottles coupled with a ship-based conductivity, temperature and depth sensor (CTD) system and surface sediment samples were collected using box corer. The results indicated that higher microplastic levels accumulated at a depth range of 5–15 m in the water column in some stations, suggesting the surface water survey was not sufficient to reflect microplastics loading in a water body. Fibers predominated microplastic types in both seawater and sediment of the Bohai Sea, which accounted for 75%–96.4% of the total microplastics. However the relatively proportion of the fibers in the deeper water layers and sediment was lower than that in the surface water. Microplastic shapes are more diverse in the sediment than in the seawater in general. The microplastic sizes changed with depth in the water column and the proportion of the size-fraction < 300 μm increased with depth, probably as a result of rapid biofouling on the small microplastics due to their higher specific surface area. Such depth distribution also implied that sampling with manta net (>330 μm) that commonly used in the oceanographic survey might underestimate microplastics abundance in the water column. Further studies are recommended to focus on the sinking behavior of microplastics and their effects on marine organisms.

Dietary consumption of contaminated vegetables may contribute to polycyclic aromatic hydrocarbon (PAH) exposure in humans; however, this exposure pathway has not been examined thoroughly. This study aims to characterize the concentrations of PAHs in six types of vegetables grown near industrial facilities in Shanghai, China. We analyzed 16 individual PAHs on the US EPA priority list, and the total concentration in vegetables ranged from 65.7 to 458.0 ng g−1 in the following order: leafy vegetables (romaine lettuce, Chinese cabbage and Shanghai green cabbage) > stem vegetables (lettuce) > seed and pod vegetables (broad bean) > rhizome vegetables (daikon). Vegetable species, wind direction, and local anthropogenic emissions were determinants of PAH concentrations in the edible part of the vegetable. Using isomer ratios and principal component analysis, PAHs in the vegetables were determined to be mainly from coal and wood combustion. The sources of PAHs in the six types of vegetables varied. Daily ingestion of PAHs due to dietary consumption of these vegetables ranged from 0.71 to 14.06 ng d−1 kg−1, with contributions from Chinese cabbage > broad bean > romaine > Shanghai green cabbage > lettuce > daikon. The daily intake doses adjusted by body weight in children were higher than those in teenagers and adults. Moreover, in adults, higher concentrations of PAHs were found in females than in males. For individuals of different age and gender, the incremental lifetime cancer risks (ILCRs) from consuming these six vegetables ranged from 4.47 × 10−7 to 6.39 × 10−5. Most were higher than the acceptable risk level of 1 × 10−6. Our findings demonstrate that planting vegetables near industrial facilities may pose potential cancer risks to those who consume the vegetables.

Concentrations of 26 brominated flame retardants (BFRs), including 19 polybrominated diphenyl ethers congeners (PBDEs), 3 isomers of hexabromocyclododecanes (HBCDs), and 4 alternative BFRs (alt-BFRs; hexabromobenzene, pentabromotoluene, 1,2-bis(2,4,6-tribromphenoxy)ethane, and decabromodiphenylethane) were determined in outdoor settled dust and pine needles collected across mainland China. BFRs were extensively found in the two matrices, with mean total concentrations at 4090 and 314 ng/g dry weight (dw), in dust and pine needles, respectively. The total BFRs concentrations in dust significantly varied among three mixed-land-use categories, with mean concentrations of 74.3, 1284, and 25,525 ng/g dw in rural, urban, and point source areas, respectively. For PBDE congeners, dust samples contained predominantly BDE-209 (69.2% of the total BFRs), whereas lower brominated PBDEs such as BDE-28 (19.7%), −47 (11.0%), and −99 (12.2%) accounted for higher proportions in pine needles. Spatial distribution of BFRs showed distinct geographical signatures with the highest levels found in South Central China. Application of McLachlan's framework to our data suggested that the uptake of BFRs in pine needles was controlled primarily by kinetically limited gaseous deposition and by particle-bound deposition. Assessment on human exposure to BFRs through outdoor dust ingestion revealed a low risk for Chinese adults and toddlers.

Marine organisms are naturally exposed to different environmental pollutants including organic pollutants and nanoparticles. The interactive effects between nanoparticles and other chemicals on aquatic organisms have raised concerns regarding the potential of nanomaterials as the vector for other chemicals. In the present study, the effect of nano zinc oxide (nZnO) on the bioavailability of triphenyltin chloride (TPTCl) was studied, and their combined acute and reproductive toxicity to the marine copepod Tigriopus japonicus were evaluated. At experimental concentration ranges of nZnO in this study, the percentage of dissolution of Zn²⁺ was relative stable (from 62% to 66%), and nZnO did not affect the bioavailability of TPTCl to the copepods. The acute toxicity of binary mixtures of nZnO/TPT was equivalent to that of the mixture of Zn²⁺/TPT. In agreement with the decrease in TPTCl's LC₅₀ values at the presence of nZnO, their interacting effect was synergistic based on response addition response surface model, and the interacting parameter was modelled to be −1.43. In addition to acute toxicity test, reproductive toxicity tests revealed that exposure to nZnO and TPTCl didn't affect the successful mating rate and the number of nauplii in the 1st brood, but they extended the time for the eggs to hatch from 2.53 days to 3.94 and 3.64 days, respectively. The exposure to nZnO/TPTCl mixture delayed the time to hatch to 5.78 days.

The implications of humic acid (HA) regarding surface properties of graphene materials and their interactions with phthalic acid esters (PAEs) are not vivid. We report the role of HA on graphene oxide (GO) and reduced graphene oxide (RGO) for sorption-desorption behavior of PAEs. Besides higher surface area and pore volume, the hydrophobic π-conjugated carbon atoms on RGO ensured prominent adsorption capacity towards PAEs in comparison to hydrophilic GO, highlighting the hydrophobic effect. After adjusting for the hydrophobic effect by calculating the hexadecane-water partition coefficient (KHW) normalized adsorption coefficient (Kd/KHW), the dimethyl phthalate (DMP) molecule portrayed a higher adsorption affinity towards RGO by π-π electron donor–acceptor (EDA) interaction for active sites on graphene interface via sieving effect. In contrast to RGO, the weak π-π EDA interactions and H-bonding was observed between the carbonyl groups of PAEs and oxygen containing functional groups on GO. There was no obvious change in morphologies of GO and RGO before and desorption as revealed by SEM and TEM images, as desorption hysteresis did not occur in all conditions. The presence of HA also resulted in shielding effect thereby decreasing the adsorption rate and capacity of diethyl phthalate (DEP) on GO and RGO, while it had little effect on DMP, probably due to the adsorbed HA as new active sites. The desorption of DMP and DEP on RGO in presence of HA was quick and enhanced. These results should be important for evaluating the fate and health risk of graphene materials and PAEs in the environment.

PM2.5 pollution is threatening human health and quality of life, especially in some densely populated regions of Asia and Africa. This paper used remotely sensed annual mean PM2.5 concentrations to explore the spatiotemporal evolution of global continental PM2.5 pollution from 2000 to 2014. The work employed an improved Bayesian space-time hierarchy model combined with a multiscale homogeneous subdivision method. The statistical results quantitatively demonstrated a ‘high-value increasing and low-value decreasing’ trend. Areas with annual PM2.5 concentrations of more than 70μg/m3 and less than 10μg/m3 expanded, while areas with of an annual PM2.5 concentrations of 10–25μg/m3 shrank. The most heavily PM2.5-polluted areas were located in northwest Africa, where the PM2.5 pollution level was 12.0 times higher than the average global continental level; parts of China represented the second most PM2.5-polluted areas, followed by northern India and Saudi Arabia and Iraq in the Middle East region. Nearly all (96.50%) of the highly PM2.5-polluted area (hot spots) had an increasing local trend, while 68.98% of the lightly PM2.5-polluted areas (cold spots) had a decreasing local trend. In contrast, 22.82% of the cold spot areas exhibited an increasing local trend. Moreover, the spatiotemporal variation in the health risk from exposure to PM2.5 over the global continents was also investigated. Four areas, India, eastern and southern China, western Africa and central Europe, had high health risks from PM2.5 exposure. Northern India, northeastern Pakistan, and mid-eastern China had not only the highest risk but also a significant increasing trend; the areas of high PM2.5 pollution risk are thus expanding, and the number of affected people is increasing. Northern and central Africa, the Arabian Peninsula, the Middle East, western Russia and central Europe also exhibited increasing PM2.5 pollution health risks.

Thallium (Tl) is a well-recognized hazardous toxic heavy metal that has been reported to have embryotoxicity and fetotoxicity. However, little is known about its association with preterm birth (PTB) in humans. We aimed to evaluate the predictors of Tl exposure and assessed its relation with PTB. The study population included 7173 mother-infant pairs from a birth cohort in Wuhan, China. Predictors of Tl concentrations were explored using linear regression analyses, and associations of Tl exposure with risk of PTB or gestational age at birth were estimated using logistic regression or generalized linear models. The geometric mean and median values of urinary Tl concentrations were 0.28 μg/L (0.55 μg/g creatinine) and 0.29 μg/L (0.53 μg/g creatinine). We found that maternal urinary Tl concentrations varied by gestational weight gain, educational attainment, multivitamin and iron supplementations. Women with Tl concentrations higher than 0.80 μg/g creatinine were at higher risk of giving birth prematurely versus those with Tl concentrations lower than 0.36 μg/g creatinine [adjusted odds ratio (95% confidence interval (CI)): 1.55 (1.05, 2.27)], and the association was more pronounced in PTB with premature rupture of membranes (PROM) rather than in PTB without PROM. About 3-fold increase in creatinine-corrected Tl concentrations were associated with 0.99-day decrease in gestational length (95% CI: −1.36, −0.63). This is the first report on the associations between maternal Tl exposure and the risk of PTB.