Enormous research interest is devoted to fabricating three-dimensional graphene-based gels (3D GBGs) toward improved conversion of solar energy by virtue of the intrinsic properties of single graphene and 3D porous structure characteristics. Here, this concise minireview is primarily focused on the recent progress on applications of 3D GBGs, including aerogels and hydrogels, in photocatalytic degradation of pollutants from water and air, such as organic pollutants, heavy metal ions, bacteria and gaseous pollutants. In particular, the preponderances of 3D GBG photocatalysts for environmental pollutants degradation have been elaborated. Furthermore, in addition to discussing opportunities offered by 3D GBG composite photocatalysts, we also describe the existing problems and the future direction of 3D GBG materials in this burgeoning research area. It is hoped that this review could spur multidisciplinary research interest for advancing the rational utilization of 3D GBGs for practical applications in environmental remediation.

Volunteer cleanup operations collect large datasets on anthropogenic litter that are seldom analyzed. Here we assess the influence of land use in both near-stream and watershed scale source domains on anthropogenic litter concentration (standing stock, kg km−1) in riparian zones of Iowa, USA. We utilized riparian litter concentration data on four classes of anthropogenic litter (metal, recyclable, garbage, and tires) from volunteer cleanup operations. Anthropogenic litter data were tested for correlation with near-stream and watershed scale land uses (developed, road density, agricultural, and open lands). Road density (road length/area) and developed land use (% area) were significantly correlated to anthropogenic litter, but agricultural (% area) and open lands (% area) were not. Metal objects correlated to near-stream road density (r = 0.79, p = 0.02), while garbage and recyclable materials correlated to watershed scale road density (r = 0.69, p = 0.06 and r = 0.71, p = 0.05 respectively). These differences in the important spatial scales of land use may be related to differences in transport characteristics of anthropogenic litter. Larger, denser metal objects may be transported more slowly through the watershed/channelized system and thus, dependent on more proximal sources, whereas smaller, less dense garbage and recyclable material are likely transported more rapidly, resulting in concentrations that depend more on watershed scale supply. We developed a linear regression model that used near-stream road density and the total amount of observed litter to predict an average anthropogenic litter density of 188 kg km−1 and a standing stock of 946 t in all Iowa streams (>4th Strahler order). The techniques employed in this study can be applied to other professional and volunteer litter datasets to develop prevention and cleanup efforts, inform investigations of process, and assess management actions.

Ambient submicron particles (PM₁) exert significant impacts on visibility degradation during severe pollution episodes of urban China. The U.S. IMPROVE algorithms are widely used for assessing the extinction effect of atmospheric aerosols, but only suitable for fine particulate matter. A proper algorithm for PM₁ extinction estimation is lacking and becomes urgent, especially after the online measurement of PM₁ species is routine by aerosol mass spectrometers. Here we conducted three-month in-situ measurements to explore mass scattering efficiencies (MSE) of PM₁ major species at a supersite of eastern China. Results indicated that MSEs of ammonium sulfate and nitrate increase quickly and then keep stable with the mass accumulation, while those of organic matter keep at ∼5.5 m²/g but with a large vibration in the whole mass range. The algorithm for reconstructing PM₁ dry scattering coefficient was derived from the integral of the variation patterns for the three PM₁ species. The algorithm was then validated and compared with other empirical algorithms through separate field measurements. Good correlations between the reconstructed and measured dry scattering coefficient were observed with R square higher than 0.9 and slope of 1.01–1.05, indicating that the reconstructed algorithm can predict the dry scattering coefficient well based on PM₁ chemical composition measurements in urban China. Our study is expected to provide observed insights on the variation of MSE in the wide mass range especially in the high region, as well as accurate formulas for ambient PM₁ dry scattering apportionment.

Over 80,000 endocrine-disrupting chemicals (EDCs) are considered emerging contaminants (ECs), which are of great concern due to their effects on human health. Quantitative structure-activity relationship (QSAR) models are a promising alternative to in vitro methods to predict the toxicological effects of chemicals on human health. In this study, we assessed a deep-learning based QSAR (DL-QSAR) model to predict the qualitative and the quantitative effects of EDCs on the human endocrine system, and especially sex-hormone binding globulin (SHBG) and estrogen receptor (ER). Statistical analyses of the qualitative responses indicated that the accuracies of all three DL-QSAR methods were above 90%, and greater than the other statistical and machine learning models, indicating excellent classification performance. The quantitative analyses, as assessed using deep-neural-network-based QSAR (DNN-QSAR), resulted in a coefficient of determination (R²) of 0.80 and predictive square correlation coefficient (Q²) of 0.86, which implied satisfactory goodness of fit and predictive ability. Thus, DNN was able to transform sparse molecular descriptors into higher dimensional spaces, and was superior for assessment qualitative responses. Moreover, DNN-QSAR demonstrated excellent performance in the discipline of computational chemistry by handling multicollinearity and overfitting problems.

Perchlorate is a pervasive, water-soluble contaminant that competitively inhibits the sodium/iodide symporter, reducing the available iodide for thyroid hormone synthesis. Insufficient iodide uptake can lead to hypothyroidism and metabolic syndromes. Because metabolism, obesity and non-alcoholic fatty liver disease (NAFLD) are tightly linked, we hypothesized that perchlorate would act as an obesogen and cause NAFLD via accumulation of lipids in liver of developing threespine stickleback (Gasterosteus aculeatus). We performed an upshift/downshift exposure regime (clean water to perchlorate treated water or perchlorate treated water to clean water) on stickleback embryos at two concentrations (30 mg/L and 100 mg/L) plus the control (0 mg/L) over the course of 305 days. Adult stickleback were euthanized, H&E stained and analyzed for liver morphology. Specifically, we counted the number of lipid droplets, and measured the area of each droplet and the total lipid area of a representative section of liver. We found that perchlorate treated fish had more and larger lipid droplets, and a larger percentage of lipid in their liver than control fish. These data indicate that perchlorate causes NAFLD and hepatic steatosis in stickleback at concentrations commonly found at contaminated sites. These data also indicate the potential of perchlorate to act as an obesogen. Future studies should investigate the obesogenic capacity of perchlorate by examining organ specific lipid accumulation and whether perchlorate induces these effects at concentrations commonly found in drinking water. Work is also needed to determine the mechanisms by which perchlorate induces lipid accumulation.

Short chain chlorinated paraffins (SCCPs) have attracted worldwide attention in recent years, due to their high production volume, persistent, bioaccumulative and toxic properties. In this study, 1-chlorodecane (CD) was selected as a model of SCCPs to explore its photochemical degradation behavior under UV irradiation. The results found that CD could be completely photochemical degradation within 120 min, and the •OH was found to be the main reactive species from both quenching experiments and electron paramagnetic resonance (EPR) results. However, the contribution of triple excited state of CD (³CD*) was still nonnegligible from the results with the absorption peak at 480 nm obtained by laser flash photolysis. Based on the identified intermediates as well as the data from theoretical chemical calculation, the detailed photochemical degradation mechanism of CD was tentatively proposed that CD firstly was excited and photo-ionized under UV irradiation, and the released Cl• in water could result in generating •OH. Then •OH initiates CD degradation mainly through the H-abstraction pathway, leading to the generation of several dehydrogenation radicals, which further generated alcohols or long chain intermediates through radical-radical reactions. The results will provide a comprehensive understanding of the degradation mechanism and environmental fates of SCCPs in water under UV irradiation.

Little is known about the impacts of maternal exposure to acute episodes of outdoor air pollution, such as that resulting from wildfires, on obstetric and neonatal outcomes. This systematic review aims to synthesise the existing literature exploring the relationship between maternal exposure to short-to medium-term changes in outdoor air quality and obstetric and neonatal outcomes.A systematic search of peer-reviewed articles using PubMed, Cochrane Library, EMBASE, ScienceDirect, Web of Science, ProQuest, GreenFILE and Scopus was conducted in January 2018 using selected search terms. Quality of included studies were assessed using the Newcastle Ottawa Scale.Eleven studies were included; eight assessed the impact of maternal exposure to air pollution exacerbation events, such as wildfires, oil well fires and volcanic eruptions, and three assessed the impact of improvement events, such as the 2018 Beijing Olympics and closure of industrial activities, on obstetric and neonatal outcomes. Studies were highly heterogenous in methodology. Six studies found a significant association between acute changes in air quality and markers of fetal growth restriction, while two did not. Three studies found an adverse association between acute changes in air quality and markers of gestational maturity, and one did not.Overall, there is some evidence that maternal exposure to acute changes in air quality of short-to medium-term duration increases the risk of fetal growth restriction and preterm birth. The relationship for other adverse obstetric or neonatal outcomes is less clear.

Cd in soils might be taken up by plants, enter the food chain and endanger human health. This study investigates the isotopic fractionation of major processes during the Cd transfer from soils to cereal grains. Thereto, soil, soil solution, wheat and barley plants (roots, straw and grains) were sampled in the field at three study sites during two vegetation periods. Cd concentrations and δ¹¹⁴/¹¹⁰Cd values were determined in all samples. The composition of the soil solution was analyzed and the speciation of the dissolved Cd was modelled. Isotopic fractionation between soils and soil solutions (Δ¹¹⁴/¹¹⁰Cd₂₀₋₅₀cₘ₋ₛₒᵢₗ ₛₒₗᵤₜᵢₒₙ = −0.61 to −0.68‰) was nearly constant among the three soils. Cd isotope compositions in plants were heavier than in soils (Δ¹¹⁴/¹¹⁰Cd₀₋₂₀cₘ₋ₚₗₐₙₜₛ = −0.55 to −0.31‰) but lighter than in soil solutions (Δ¹¹⁴/¹¹⁰Cdₛₒᵢₗ ₛₒₗᵤₜᵢₒₙ₋ₚₗₐₙₜₛ = 0.06–0.36‰) and these differences correlated with Cd plant-uptake rates. In a conceptual model, desorption from soil, soil solution speciation, adsorption on root surfaces, diffusion, and plant uptake were identified as the responsible processes for the Cd isotope fractionation between soil, soil solution and plants whereas the first two processes dominated over the last three processes. Within plants, compartments with lower Cd concentrations were enriched in light isotopes which might be a consequence of Cd retention mechanisms, following a Rayleigh fractionation, in which barley cultivars were more efficient than wheat cultivars.

Polychlorinated biphenyls (PCBs) are a class of persistent organic pollutants that have been shown to be related to the occurrence of type 2 diabetes mellitus (T2DM). Nevertheless, it is necessary to further explore the development of T2DM caused by PCBs and its underlying mechanisms. In the present study, 21-day-old C57BL/6 male mice were orally treated with Aroclor 1254 (0.5, 5, 50 or 500 μg kg−1) once every three days. After exposure for 66 d, the mice showed impaired glucose tolerance, 13% and 14% increased fasting serum insulin levels (FSIL), and 63% and 69% increases of the pancreatic β-cell mass in the 50 and 500 μg kg−1 groups, respectively. After stopping exposure for 90 d, treated mice returned to normoglycemia and normal FSIL. After re-exposure of these recovered mice to Aroclor 1254 for 30 d, fasting plasma glucose showed 15%, 28% and 16% increase in the 5, 50 and 500 μg kg−1 treatments, FSIL exhibited 35%, 27%, 30% and 32% decrease in the 0.5, 5, 50 or 500 μg kg−1 groups respectively, and there was no change in pancreatic β-cell mass. Transcription of the pancreatic insulin gene (Ins2) was significantly down-regulated in the 50 and 500 μg kg−1 groups, while DNA-methylation levels were simultaneously increased in the Ins2 promoter during the course of exposure, recovery and re-exposure. Reduced insulin levels were initially rescued by a compensative increase in β-cell mass. However, β-cell mass eventually failed to make sufficient levels of insulin, resulting in significant increases in fasting blood glucose, and indicating the development of T2DM.

In the past few decades, extensive epidemiological studies have focused on exploring the adverse effects of PM₂.₅ (particulate matters with aerodynamic diameters less than 2.5 μm) on public health. However, most of them failed to consider the dynamic changes of population distribution adequately and were limited by the accuracy of PM₂.₅ estimations. Therefore, in this study, location-based service (LBS) data from social media and satellite-derived high-quality PM₂.₅ concentrations were collected to perform highly spatiotemporal exposure assessments for thirteen cities in the Beijing-Tianjin-Hebei (BTH) region, China. The city-scale exposure levels and the corresponding health outcomes were first estimated. Then the uncertainties in exposure risk assessments were quantified based on in-situ PM₂.₅ observations and static population data. The results showed that approximately half of the population living in the BTH region were exposed to monthly mean PM₂.₅ concentration greater than 80 μg/m³ in 2015, and the highest risk was observed in December. In terms of all-cause, cardiovascular, and respiratory disease, the premature deaths attributed to PM₂.₅ were estimated to be 138,150, 80,945, and 18,752, respectively. A comparative analysis between five different exposure models further illustrated that the dynamic population distribution and accurate PM₂.₅ estimations showed great influence on environmental exposure and health assessments and need be carefully considered. Otherwise, the results would be considerably over- or under-estimated.