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Benzo[a]pyrene (B[a]P) as a representative polycyclic aromatic hydrocarbons is concerned by global scientists in various fields, but its biological and biochemical actions in soil-wheat systems are still rarely reported. The B[a]P as a ubiquitous soil pollutant possesses varied contents in real environment, and herein was studied in systems of soil and wheat to obtain relative results to reveal their variations in different systems. Its bioavailability (extractability and bioaccumulation) and basic biological toxicity were tested based on three typical soil types (red, black, and brown) in China and spiked amounts (0.1, 1, and 10 mg/kg) with several orders of magnitude. Results showed that B[a]P concentrations in soil-wheat systems extracted by HPCD were insignificantly (p > 0.05) higher than Tenax-TA, and varied with soil types and spiked concentrations. Besides, the root and shoot length were mostly inhibited, in a range of -21.85%-26.35% and -0.48%-54.85%, respectively, by B[a]P in different soil types and increased with its increasing concentration. Comparatively, higher bioconcentration factor and translocation factor values were observed under lower group in red soil-wheat systems, and higher spiked groups in black and brown soil-wheat systems. Moreover, inhibitive effects posed by B[a]P were mainly targeted at wheat shoots in these soils. The simultaneous studies provided a comparable knowledge of B[a]P in ecosystems of different soil types combined with different plant species due to lots of variations, further to serve for contaminated soil remediation and sustainable agricultural management.

Engineered nanomaterials (ENMs), especially transition metal dichalcogenide (TMDC), have received great attention in recent years due to their advantageous properties and applications in various fields and are inevitably released into the environment during their life cycle. However, the effect of natural nanocolloids, widely distributed in the aquatic environment, on the environmental transformation and ecotoxicity of ENMs remains largely unknown. In this study, the effects of natural nanocolloids were compared to humic acid on the environmental transformation and ecotoxicity of single-layer molybdenum disulfide (SLMoS2), a representative TMDC. SLMoS2 with nanocolloids or humic acid (HA) enhanced their dispersion and Mo ion release in deionized water. Nanocolloids induced growth inhibition, reactive oxygen species (ROS) elevation, and cell permeability. Low-toxicity SLMoS2 combined with nanocolloids will enhance the above adverse effects. SLMoS2-nanocolloids induced serious damage (cell distortion and deformation), SLMoS2 internalization, and metabolic perturbation on Chlorella vulgaris (C. vulgaris). In contrast, the addition of HA induced the growth promotion and lower ROS level, inhibited the internalization of SLMoS2, and mitigated metabolic perturbation on C. vulgaris. This work provides insights into the effect of natural nanocolloids on the behaviors and biological risks of ENMs in aquatic environments, deserving substantial future attention.

Cotton is one of the most important raw materials for textile and clothing production. The main drawbacks of cotton fibers are their poor mechanical properties and high flammability. Compared with some synthetic polymer fibers, cotton fabrics treated with modern flame-retardant and reinforcement finishes often cannot meet rigid military specifications. Polypyrrole–magnesium oxide (ppy–MgO) and polypyrrole–magnesium oxide–carbon nanotube (ppy–MgO–CNT) composites were prepared with various weight ratios by in situ chemical polymerization method. 1,2,3,4-Butane tetracarboxylic acid (BTCA) was used as a cross-linking agent in the presence of sodium hypophosphite (SHP). The composite sol was coated on cotton fabric using the pad-dry-cure technique. The coated cotton fabrics were characterized by SEM, EDAX, XRD, UV-DRS and FT-IR analysis, and tested for flame retardant and UPF application. The flame-retardant study showed a maximum char length of 0.3 cm and the char yield was about 49% for the ppy–MgO–CNT composite. For that UPF application, a 30 UPF value was shown for the ppy–MgO–CNT composite. In the case of the antibacterial study, the zone of inhibition was observed for all of the test samples against MRSA and PAO1 bacteria. The zone of inhibition showed as 4.0, 3.0 mm for the ppy–MgO–CNT composite. Hence, the ppy–MgO–CNT composite was found to be efficient.

Interactions between microorganisms and clay minerals influence the transport and cycling of metal contaminants in both marine and terrestrial environments. The present study was conducted to quantify the adsorption of dissolved cadmium, Cd(II), under seawater-like conditions to the marine cyanobacterium Synechococcus sp. PCC 7002, three common clay minerals (kaolinite, montmorillonite and illite), as well as cell-clay aggregates. We show here that the Synechococcus-only experiments removed the most Cd above pH 5.5, followed in decreasing order by aggregates of 50% cells:50% individual clays, aggregates of cells and all 3 clays, and individual clays. Electron microscope imaging showed that clays associated in a tangential edge-on orientation to the cells in Synechococcus-clay mineral aggregates. A non-electrostatic surface complexation modeling approach was used to fit Cd adsorption onto Synechococcus cells and individual clay minerals. The resulting Cd binding constants were then used in consort with surface functional group pKa values and site concentrations to accurately predict the extent of Cd adsorption onto the Synechococcus-clay mineral aggregates using the component additivity (CA) approach. We observed that the addition of cyanobacterial cells to clay mineral suspensions led to significantly larger mean aggregate sizes of clay minerals, enhancing the clay sedimentation rate. Although specifically focused on Cd, our study indicates that the ratio of bacterial plankton to clay minerals is an important determinant in terms of understanding the rate with which metals are transferred from the water column to the seafloor.

There is a growing need to eliminate antibiotic resistance genes (ARGs) in the environment and mitigate widespread antibiotic resistance. Graphitic carbon nitride (g-C3N4) was successfully synthesized via facile thermal polymerization approach and its potential for adsorption treatment of ARGs in water was examined. Batch adsorption experimental results revealed that g-C3N4 powders had robust adsorption activity for the gene ampC and ermB. Adsorption kinetics and isotherms were systematically investigated to explain the adsorption mechanism. The apparent adsorption equilibrium could be reached within 180 min. The adsorption process effectively removed ARGs (ampC and ermB) from water with 3.2 log and 4.2 log reductions, respectively. In addition, experimental data were analyzed by several models and simulated well with Langmuir isotherm and pseudo-second-order model. It indicated that adsorption process might be dominated by the chemical rate-limiting step. Moreover, the effects of temperature and pH on the removal of ARGs were conducted and the isoelectric point (IEP) was obtained. Finally, we have demonstrated that the g-C3N4 is a novel adsorbent and can be used as column packing to remove ARGs by filtration.

Graphene-based nanomaterials (GBNs) are likely to be entering the soil environment in increasing amounts via consumer products. However, the disturbance of bacterial communities and their associated ecological functions by GBNs remains elusive. We performed a soil incubation experiment with the addition of graphene oxide (GO) and reduced graphene oxide (RGO). The Illumina sequencing technique was used to investigate changes in bacterial communities, and the functional groups of the communities were analyzed using the functional annotation of prokaryotic taxa database. After 90 days of exposure, RGO induced a lower bacterial richness than GO. However, GO induced larger changes in community composition and functions than RGO. After exposure to GBNs, some of the functional groups associated with organic matter degradation and biogeochemical cycling of nitrogen and sulfur decreased. However, the functional group associated with aromatic compound degradation increased, possibly because GBNs contain rich aromatic hydrocarbon structures, which are tolerated by this functional group.

Antibiotic resistance genes (ARGs) are considered to be a type of emerging contaminant; their interaction with biochar (BC) could affect their dissemination and fate in the environment. Although adsorption of ARGs onto bulk-BC has been reported, the interaction with nanosized BC (nano-BC) is largely unknown. In this study, the interactions of a model extracellular DNA (eDNA, calf thymus DNA) and two typical ARGs (ampC and ermB) extracted from a natural river with bulk- and nano-BCs from two pyrolysis temperatures (400 and 700 °C) were investigated. Only adsorption was observed on bulk-BCs, while not only adsorption but also fragmentation of these eDNA molecules was found to occur on nano-BCs. Also, their replication was greatly inhibited by nano-BCs. The electron paramagnetic resonance results indicated that hydroxyl radicals produced from persistent free radicals (PFRs) on nano-BCs played a major role in the damage of eDNA. Moreover, the direct contact with nonradical reacting sites and PFRs on nano-BCs also contributed to the decay of eDNA. Comparatively, PFRs in bulk-BCs were difficult to be reached by eDNA because of steric hindrance and played a negligible role in destroying eDNA. These findings highlight the importance of the size effect in evaluating the reactivity and related environmental risks of PFRs on BC and improve our understanding on the interaction between ARGs and BC.

Emerging transition-metal dichalcogenide (TMDC) nanosheets, such as WS2 nanosheets, have shown tremendous potential for use in many fields such as intelligent manufacturing and environmental protection. However, considerable knowledge gaps still exist regarding the impact of TMDCs on environmental risks, especially risks involving organic pollutants. Here, a synergistic toxicity between WS2 nanosheets and organic pollutants (triclosan or tris(1,3-dichloro-2-propyl) phosphate) was found using the median-effect and combination index equations. In particular, the effect of synergy had a higher magnitude at low cytotoxicity levels and a noncytotoxic concentration of WS2 nanosheets clearly enhanced the cytotoxicity and intracellular accumulation of organic pollutants. On the one hand, WS2 nanosheets damaged the plasma membrane and cytoskeleton, resulting in increased membrane permeability and organic pollutant uptake. On the other hand, as shown by fluorescence substrate accumulation experiments and molecular dynamics simulations, WS2 nanosheets affected the secondary structure of the efflux pumps and competitively bound with efflux pumps, blocking xenobiotic removal. This work emphasized that TMDCs, especially at the noncytotoxic level, in combination with organic pollutants caused damage that cannot be ignored, providing insight into comprehensive safety assessment and the specific toxicological mechanisms of TMDCs that accompany organic pollutant exposure.

The safety of microplastics (MPs) and associated health effects has been one of the major concerns worldwide. However, the role of photoaging toward the risk of MPs in water ecosystems remains inconclusive yet. In this study, the size of polyamide (PA, ∼32.50 μm) MPs was obviously decreased after photoaging in water containing fulvic acid (FA) and humic acid (HA) (∼19.75 and ∼24.30 μm, respectively). Nanoplastics were formed (4.65% and 2.03%, respectively) and hydrophilia and colloidal stability was improved due to the formation of oxygen-containing functional groups. FA-aged PA exhibited higher inhibition on body length and weight of developing zebrafish than HA-aged and pristine PA. Photoaged MPs in intestine were more difficult to be depurated by zebrafish, leading to the disappearance of intestinal folding, shedding of more enterocytes, and emaciation of intestinal microvilli. Dietary lipid digestion in larvae was inhibited by aged PA due to oxidative stress-triggered lipid peroxidation and inhibition of lipase activities and bile acids secretion. Exposure of photoaged MPs down-regulated genes (cd36, dgat1a, dgat2, mttp, etc.) associated with triglyceride resynthesis and transportation, resulting in lipid maladsorption and growth inhibition. Our findings highlight the potential negative effects of environmentally aged MPs on diet digestion and nutrient assimilation in fish.

Azo dye pollution has become a worldwide issue, and the current treatment methods can hardly meet the expected emission standards. Microbial electrochemical systems (MESs) show promising applications for decolorization, but their performance critically depends on the microorganisms. Electrode modification is an interesting method of improving decolorization performance. However, the mechanisms of how the modification can affect microbial communities and the decolorization process remain unclear. Here, a modified anode with polyaniline (PANI) and graphene was fabricated via electro-deposition. Consequently, the highest decolorization efficiency was obtained. The Congo red (CR) decolorization rate of the MESs with the PANI/graphene-modified electrode (PG) reached 90% at 54 h. By contrast, the CR decolorization rates of the MESs with the PANI-modified electrode (P) and those of the MESs with the unmodified electrode (C) only reached 68% and 79%, respectively. Results of the microbial community analysis showed abundant Methanobrevibacter arboriphilus in PG (11%), which was 5.5 times that in C (2%) at 18 h. This phenomenon may be related to the rapid decolorization. The upregulated metabolism pathways, including arginine and proline metabolism, purine metabolism, arginine biosynthesis, and riboflavin metabolism, provided more electron shuttles and redox mediators that facilitated the extracellular electron transfer. Therefore, the PG-modified electrode facilitated the decolorization by altering certain metabolic pathways. This study can help to improve the guideline on the potential application of MESs for wastewater treatment.

Cuprous oxide (Cu2O), an earth-abundant, low-cost metal-oxide semiconductor, has received enormous attention for its CO2 reduction ability in aqueous media by photochemical, photoelectrochemical and electrochemical methods. An unresolved problem with all of these approaches, however, is the instability of the Cu2O caused by its tendency to undergo an irreversible redox disproportionation reaction. Here, we report a way to circumvent this troublesome behaviour of Cu2O by driving the CO2 reduction in the gas-phase via heterogeneous photocatalytic hydrogenation. To this end, Cu2O nanocubes with surfaces comprising mixed oxidation-state copper Cu(0,I,II) sites, oxygen vacancies [O] and hydroxyl OH groups were synthesized. These surfaces enable heterolysis of H2 and adsorption of CO2 under mild conditions; they facilitate the reverse water–gas shift reaction, while rendering the redox disproportionation reaction reversible. This synergism provides Cu2O nanocubes with high photocatalytic activity and stability. Cu2O is a promising photocatalyst, although its stability is compromised by a disproportionation reaction that leads to the formation of Cu and CuO. Now, a method is reported to stabilize Cu2O nanocubes, rendering them highly active and stable for the photocatalytic reverse water–gas shift reaction.

Understanding environmental fate is a prerequisite for the safe application of nanoparticles. However, the fundamental persistence and environmental transformation of single-layer molybdenum disulfide (SLMoS2, a 2D nanosheet attracting substantial attention in various fields) remain largely unknown. The present work found that the dissolution of SLMoS2 was pH and dissolved oxygen dependent and that alterations in phase composition significantly occur under visible light irradiation. The 1T phase was preferentially oxidized to yield soluble species (MoO42- and SO42-), and the 2H phase remained as a residual. The transformed SLMoS2 exhibited a ribbon-like and multilayered structure and low colloidal stability due to the loss of surface charge. Dissolved oxygen competitively captured the electrons of SLMoS2 to generate superoxide radicals and accelerated the dissolution of nanosheets. Compared to pristine 1T-phase SLMoS2, the transformed 2H-phase SLMoS2 could not easily enter algal cells and induced a low developmental inhibition, oxidative stress, plasmolysis, photosynthetic toxicity and metabolic perturbation. The downregulation of amino acids and upregulation of unsaturated fatty acids contributed to the higher toxicity of 1T-phase SLMoS2. The dissolved ions did not induce apparent phytotoxicity. The connections between environmental transformation (phase change and ion release) and phytotoxicity provide insights into the safe design and evaluation of 2D nanomaterials.

The performance of a microbial fuel cell (MFC) that uses an as-prepared zeolitic imidazolate framework-8 (ZIF-8) as air-cathode catalyst is investigated. Due to the composite pore structure, large specific surface area (1416.19 m2/g), and high pore volume (0.55 cm³/g), the 0.5 mg/cm2 ZIF-8 catalyst can enhance the oxygen reduction reaction (ORR) in electrodes and achieve a maximum power density of 2103.4 mW/m2. X-ray photoelectron spectroscopy demonstrates the abundant existence of pyridinic nitrogen in ZIF-8 that meets the prerequisite for making an effective and efficient catalyst for ORR, and the carbon atoms adjacent to the pyridinic nitrogen are considered as the active sites with Lewis basicity. In addition, the graphitization of carbon in ZIF-8 enhanced the electronic conductivity and corrosion resistance during electrocatalysis. MFCs that use ZIF-8 as the catalyst can regularly work more than 110 h during a feeding period, which is considerably longer than that of the MFCs modified by Pt/C (approximately 40 h). The composite pore structure in ZIF-8 guarantees an rapid mass transfer rate on the three-phase boundary, which results in a faster ORR rate. These advantages make ZIF-8 a promising alternative catalyst for ORR of air-cathode MFC.

As an important type of typical synthetic azo dyes, the use of sudan I-IV dyes has been of concern worldwide because of their wide applications and illegal addition into various foodstuffs, potentially resulting in water and soil pollution and having adverse effects on human health and ecosystems. However, to date, little has been reported regarding the environmental levels of these dyes and the risks that they pose to human health and ecosystems. Understanding the responses of soil enzymes, functional groups of bacteria and microbial communities to sudan dyes is of great importance to reveal their effect on the soil environment. In this study, we performed a toxicological study on the specific and overall effects of sudan I-IV dyes on the activity of soil enzymes including catalase, urease, and alkaline phosphatase after a 2- and 7-day exposure, functional groups of soil bacteria including nitrogen-fixing, ammonia-oxidizing, and denitrifying bacteria on day 14, and the structure and diversity of soil microbial community compositions on day 30. The results showed that sudan I-IV affected the activity of the soil enzymes, the abundance of the bacterium functional groups, and the structure and diversity of microbial community compositions, and the effects varied by sudan dyes I-IV, the exposure concentration, and the exposure time.

Combined toxicity is a critical issue in risk assessment of contaminants. However, very little is known about the joint effects of graphene oxide (GO, a crucial 2-dimensional carbon material) and hexavalent chromium (Cr6+, a widespread heavy metal), particularly with respect to the critical period of embryogenesis. In this study, the combined toxicity of GO and Cr6+ was evaluated through embryo-larval toxicity test in Danio rerio (zebrafish). Results indicated that the co-exposure of Cr6+ (1 mg/L) and GO (0.01 mg/L) inhibited hatching and spontaneous movement of embryos, but no significant changes were found in the single Cr6+ or GO group. Compared with the single GO or Cr6+ exposure, their co-exposure (GO+Cr6+) significantly enhanced the teratogenicity in a concentration-dependent pattern, and the spinal curvature was observed as the main deformity. GO+Cr6+ changed the protein secondary structures of embryos result of the generation of ROS and oxidative stress. The degradations of vertical myosepta and cartilages were observed in co-exposure group, suggesting that GO+Cr6+ disrupted the development of musculoskeletal system. The genes col11a1a, col2a1a and postnb were down-regulated but the genes acta1b and mmp9 were up-regulated by GO+Cr6+. The interactions between Cr6+ and GO demonstrated that the morphology, structure, and surface properties of GO were modified by Cr6+. The enhanced defects and O-containing groups of GO could trap more β-sheets, induced oxidative stress, disturbed the development of skeletal muscles and cartilages in zebrafish. These data suggested that GO+Cr6+ enhanced their joint toxicity due to the variation of nanoparticle properties. This finding is important for assessing the ecological risk of graphene family nanomaterials in the natural environment.

Microplastics (MPs) and nanoplastics (NPs) have inevitably entered and accumulated in terrestrial ecosystems. Recently, the report on MPs/NPs taken-up by crop plants has raised particular concerns. However, molecular mechanisms underlying the interaction of MPs/NPs and crop plant are still vague and elusive. To address this scientific gap, we identified differentially expressed genes (DEGs) and performed co-expression network analyses in hydroponically grown wheat (Triticum aestivum L.) with ambient polystyrene NPs (PSNPs) concentration (0-10 mg/L). PSNPs could significantly shape the gene expression pattern in wheat with a tissue-specific mode. Four regulatory modules associated with the plant performance and nutrient capture were identified using WGCNA analysis. In addition, carbon metabolism, amino acid biosynthesis, MAPK signaling pathway-plant, plant hormone signal transduction, and plant-pathogen interaction were the most enriched KEGG pathways for all DEGs and target module eigengenes. These results confirm that NPs-induced genetic changes are the dominating driven forces for the observed plant growth or defense responses, shedding new light on the molecular mechanism and environmental implication behind the interaction of NPs and crop plants.

The increasing applications of single-layer molybdenum disulfide (SLMoS2) pose great potential risks associated with environmental exposure. This study found that metallic-phase SLMoS2 with nanoscale (N-1T-SLMoS2, ∼400 nm) and microscale (M-1T-SLMoS2, ∼3.6 μm) diameters at 10-25 mg/L induced significant algal growth inhibition (maximum 72.7 and 74.6%, respectively), plasmolysis, and oxidative damage, but these alterations were recoverable. Nevertheless, membrane permeability, chloroplast damage, and chlorophyll biosynthesis reduction were persistent. By contrast, the growth inhibition (maximum 55.3%) and adverse effects of nano-sized semiconductive-phase SLMoS2 (N-2H-SLMoS2, ∼400 nm) were weak and easily alleviated after 96 h of recovery. N-1T-SLMoS2 (0.011 μg/h) and N-2H-SLMoS2 (0.008 μg/h) were quickly biodegraded to soluble Mo compared with M-1T-SLMoS2 (0.004 μg/h) and excreted by algae. Incomplete biodegradation of SLMoS2 (26.8-43.9%) did not significantly mitigate its toxicity. Proteomics and metabolomics indicated that the downregulation of proteins (50.7-99.2%) related to antioxidants and photosynthesis and inhibition of carbon fixation and carbohydrate metabolism contributed to the persistent phytotoxicity. These findings highlight the roles and mechanisms of the size and phase in the persistent phytotoxicity of SLMoS2, which has potential implications for risk assessment and environmental applications of nanomaterials.

Electroactive biofilm (EAB) sensor had shown great potential in the field of early warning of toxicants in water because of the low-cost and broad-spectrum. However, the traditional calculation of sensitivity strongly relied on the time and concentration gradient which weakened time-efficiency of the sensor. Moreover, the sensitivity could be further improved to respond trace concentrations. Here EAB sensors with different substrate concentrations were formed to respond different concentrations formaldehyde ranging from 1 ppm to 50 ppm and immediate current attenuation (ICA) was induced to evaluate the sensitivity. The ICA (~70 s) exhibited a shorter time than that calculated by calculable sensitivity (CS) and current attenuation (CA), which not only achieved the response of trace concentration but also improved the time-efficiency of the sensor. The EAB formed with 0.1 g/L acetate (EAB-0.1) had a 380% higher sensitivity than that formed with 1.0 g/L acetate (EAB-1.0), leading to a significant electrochemical toxicity response to 1 ppm of formaldehyde. The results of electrochemical response coefficient confirmed that EAB-0.1 was 1.5–6.3 times of that formed with acetate from 0.2 to 1.0 g/L, which was related with microbial community and component of EAB as described in our previous study. Our findings demonstrated that calculation of sensitivity could be optimized to reflect time-efficiency and EAB with limit acetate could be applied in trace toxicant detection.

Application of transition metal dichalcogenide (TMDC) nanosheets with different phases have attracted much attention in various fields. However, the effects of TMDC phases on environmental biology remain largely unknown. In this study, chemically exfoliated WS2 nanosheets (Ce-WS2, mainly the 1T phase) and annealed exfoliated WS2 nanosheets (Ae-WS2, 2H phase) were fabricated to serve as representative TMDC nanomaterials. Ce-WS2 showed higher levels of cellular uptake, oxidative stress, lipid peroxidation, membrane damage, and inhibition of photosynthesis than Ae-WS2 in Chlorella vulgaris. These differences were attributed to the higher electron conductivity and higher separation efficiency of electrons and holes in the 1T phase, a typical feature of Ce-WS2. Correspondingly, 2H-phase Ae-WS2 exhibited lower photooxidation/reduction activity and a lower ability to generate reactive oxygen species (mainly •OH) under visible-light irradiation. 1T-phase Ce-WS2 dissolved more readily than Ae-WS2 and released more...

An experimental study on adsorption and desorption behaviors of rhodamine B (RhB) with/without cadmium ion (Cd2+) on a coastal soil was carried out in the face of the scarce studies on its environmental behaviors, especially its combined pollution with metal ions. The implications on mariculture and seafood safety, rarely concerned either, were also analyzed for providing a new insight between azo dyes and them. It showed that the adsorption of RhB on the tested soil was affected by Cd2+ and could be better fitted by the Freundlich model and dominantly identified as chemical adsorption according to the threshold of ΔG0 (40 kJ/mol). There is a positive hysteresis on the desorption of RhB, which was generally strengthened with the increasing concentration of RhB but generally weakened in the presence of Cd2+. The azo dyes including RhB and heavy metals such as Cd, as the major class of typical pollutants in coastal environment, are closely related to the mariculture and seafood safety. In the consideration of three aspects including potential pollutants for the mariculture, potential risks for seafood safety, and potential relationships between dyes and mariculture and seafood safety, their implications were further clarified.

The increasing production and applications of graphene oxide (GO, a novel carbon nanomaterial) have raised numerous environmental concerns regarding its ecological risks. Triphenyl phosphate (TPhP) disperses in water and poses an increasing hazard to the ecosystem and human health. It is critical to study the environmental responses and molecular mechanisms of GO and TPhP together to assess both chemicals; however, this information is lacking. The present work revealed that GO promoted the bioaccumulation of TPhP in zebrafish larvae by 5.0%-24.3%. The TPhP-induced growth inhibition of embryos (malformation, mortality, heartbeat, and spontaneous movement) at environmentally relevant concentrations was significantly amplified by GO, and these results were supported by the downregulated levels of genes and proteins associated with cytoskeletal construction and cartilage and eye development. TPhP induced negligible alterations in the genes or proteins involved in oxidative stress and apoptosis, but those related proteins were all upregulated by GO. GO and TPhP coexposure activated the mTOR signaling pathway and subsequently promoted apoptosis in zebrafish by potentiating the oxidative stress induced by TPhP, presenting synergistic toxicity. These findings highlight the potential risks and specific molecular mechanisms of combining emerging carbon nanomaterials with coexisting organic contaminants.

A novel Au-graphene oxide (GO)-Co3O4 hollow sphere (Au/GO-Co3O4) was synthesized and its potential in binding with antibiotic resistance genes (ARGs) and inhibiting their replication was examined in this study. Tetracycline-resistant genes (tetA) with two amplicon lengths were selected as the model ARGs due to its highly detected in the environment. The Au/GO-Co3O4 composite was synthesized using tetra-n-butylammonium bromide (TBAB) as a mediating proxy. We found that it could bind with tetA and consequently inhibit its replication to a greater extent compared with pure Co3O4 and GO-Co3O4 hybrid. Furthermore, the Au-GO-Co3O4 composite was more efficient in binding with short fragments of tetA-ARGs (S-tetA) than long fragments (L-tetA). The interaction mechanism between the composite and tetA was systematically analyzed using spectra methods (FTIR, Raman, UV–Vis, and fluorimetric spectra), isolated filtrate assays, and gel electrophoresis. It is found that the adsorption of both GO and gold nanoparticles for tetA as well as cleavage effect of cobalt oxide/cobalt ions played a critical role in the capture and damage of tetA. Furthermore, we found that the interaction of both Co3O4 and GO-Co3O4 with tetA was mainly through intercalation mechanism, however, that of Au/GO-Co3O4 with tetA was mainly through groove binding mechanism. These findings in this study throw light on the new approaches for purification of ARGs contaminated water and elimination of antibiotic resistance of ARGs by novel inhibitor.

Single-layer molybdenum disulfide (SLMoS2) are applied as a hot 2D nanosheet in various fields involving water treatments. Both intentional design and environmental or biological processes induce many nanoholes in SLMoS2. However, the effects of nanoholes on the environmental stability and ecotoxicity of SLMoS2 remain largely unknown. The present work discovered that visible-light irradiation induced nanoholes (diameters, approximately 20 nm) in the plane of SLMoS2, with irregular edges and increased interplanar crystal spacing. The ratios of Mo to S in pristine and transformed SLMoS2 were 0.53 and 0.33, respectively. After 96 h exposure at concentrations from 0.1 to 1 mg/L, the above nanoholes promoted algal division, induced a stress-response hormesis, decreased the generation of •OH, and mitigated the cell shrinkage and wall rupture of Chlorella vulgaris induced by SLMoS2. In terms of stress response, the nanohole-bearing SLMoS2 induced fewer vacuoles and polyphosphate bodies of Chlorella vulgaris than the pristine form. Metabolomic analysis revealed that nanoholes perturbed the metabolisms of energy, carbohydrates, and fatty acids. This work proposes that nanoholes cause obvious effects on the environmental fate and ecotoxicity of SLMoS2 and that the environmental risks of engineered nanomaterials should be reevaluated using nanohole-bearing rather than pristine forms for testing.

Hydrolysis is generally considered as the main pathway for the degradation of ester-type pollutants in aquatic environments. In this study, we found that when methanol or ethanol presented as the external carbon in the activated sludge, transesterification is very important for the degradation of para-hydroxybenzoic acid esters (parabens). In the activated sludge solutions with 1% methanol added, contribution of transesterification to the degradation of the propyl substituted paraben (PrP) and ethyl substituted paraben (EtP) accounted for 46% and 83%, respectively, in the early stage of the reaction. This indicates that in aquatic environments with alcohols presence, parabens prefer to form small molecule homologues than hydrolysis to acid. The predominant transesterification in the activated sludge is related to enzyme preference. Amano lipase from Pseudomonas fluorescens was verified to catalyze hydrolysis and transesterification of parabens, while the latter was dominant in water solution with 1% methanol or ethanol. Considering the common application of small molecular alcohols as the external carbon sources in wastewater treatment plants, transesterification might be an important pathway for the degradation of parabens pollutants in these engineering aquatic environments.

Nanocolloids are widespread in natural water systems, but their characterization and ecological risks are largely unknown. Herein, tangential flow ultrafiltration (TFU) was used to separate and concentrate nanocolloids from surface waters. Unexpectedly, nanocolloids were present in high concentrations ranging from 3.7 to 7.2 mg/L in the surface waters of the Harihe River in Tianjin City, China. Most of the nanocolloids were 10-40 nm in size, contained various trace metals and polycyclic aromatic hydrocarbons, and exhibited fluorescence properties. Envelopment effects and aggregation of Chlorella vulgaris in the presence of nanocolloids were observed. Nanocolloids entered cells and nanocolloid-exposed cells exhibited stronger plasmolysis, chloroplast damage and more starch grains than the control cells. Moreover, nanocolloids inhibited the cell growth, promoted reactive oxygen species (ROS), reduce the chlorophyll a content and increased the cell permeability. The genotoxicity of nanocolloids was also observed. The metabolomics analysis revealed a significant ( p0.05) downregulation of amino acids and upregulation of fatty acids contributing to ROS increase, chlorophyll a decrease and plasmolysis. The present work reveals that nanocolloids, which are different from specific, engineered nanoparticles (e.g., Ag nanoparticles), are present at high concentrations, exhibit an obvious toxicity in environments, and deserve more attention in the future.

Molybdenum disulfide (MoS2) poses great potential in water treatment as a popular transition metal dichalcogenide, arousing considerable concern regarding its fates and risk in aquatic environments. This study revealed that the interplay with extracellular polymeric substances (EPS) of freshwater algae significantly changed the properties and toxicity of MoS2 to aquatic fish. The predominant binding of aromatic compounds, polysaccharides, and carboxyl-rich proteins in EPS on the 1T polymorph of MoS2 via hydrophilic effects and the preferential adsorption of carboxylic groups contributed to morphological alterations, structural disorders (band gap and phase alterations), and the attenuated aggregation of MoS2 in aqueous solutions. Electron charge transfer and n-π* interactions with EPS decreased the catalytic activity of MoS2 by inhibiting its capability of generating reactive intermediates. The dissolution of MoS2 slowed down after interacting with EPS (from 0.089 to 0.045 mg/L per day) owing to rapid initial oxidation (i.e., forming Mo-O bond) and carbon grafting. Notably, the morphological and structural alterations after EPS binding alleviated the toxicity (e.g., malformation and oxidative stress) of MoS2 to infantile zebrafish. Our findings provide insights into the environmental fate and risk of MoS2 by ubiquitous EPS in natural waters, serving as valuable information while developing water treatment processes accordingly.

Electronic regulation via interfacial formation is identified as a versatile strategy to improve the electrocatalytic activity. Herein, we report a feasible electrospinning-pyrolysis approach for the in-situ immobilization of Co/MnO hetero-nanoparticles onto N,S co-doped carbon nanotubes/nanofiber-integrated hierarchical branched superstructures (abbreviated as Co/MnO@N,S-C NT/CNFs hereafter). The simultaneous realization of interfacial engineering and nanocarbon hybridization renders the fabricated Co/MnO@N,S-C NT/CNFs with abundant firmly anchored active sites, modified electronic configuration, improved electric conductivity, efficient mass transport pathways, and significantly reinforced stability. Profiting from the compositional synergy and architectural advantages, the Co/MnO@N,S-C NT/CNFs exhibit outstanding ORR activity, superior tolerance to methanol, and excellent long-term stability in KOH electrolyte. More encouragingly, as a proof-of-concept demonstration, the rechargeable aqueous and flexible all-solid-state Zn-air batteries using Co/MnO@N,S-C NT/NFs + RuO2 as the air-cathode afford higher power densities, larger specific capacities and superb cycling stability, outperforming the state-of-the-art Pt/C + RuO2 counterparts. This work demonstrates the great contribution of heterointerfaces for oxygen electrocatalysis.

Elaborate design of cost-effective and highly-efficiency bifunctional electrocatalysts towards the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is critically essential for the advancement of rechargeable metal-air batteries. Herein, we develop a straightforward and scalable hydrogel-bridged pyrolysis strategy for the exquisite construction of a “ship-in-a-bottle”-structured bifunctional catalyst consisting of fine CoFe nanoparticles encapsulated inside the carbon nanowall-assembled frameworks (abbreviated as CoFe@N-CNWF hereafter). The deliberate design of such intriguing hierarchical honeycomb-like architecture with tightly confined CoFe nanoparticles and open configuration endows the as-fabricated CoFe@N-CNWF with sufficient well-dispersed active sites, rapid charge transfer efficiency, accelerated mass diffusion and robust mechanical strength. Consequently, the resultant CoFe@N-CNWF catalyst shows outstanding catalytic performance toward the ORR and OER with high activity and long-term stability. More encouragingly, a rechargeable Zn–air battery using CoFe@N-CNWF as the air cathode displays superb energy density, high energy efficiency and robust reversibility, surpassing the state-of-the-art precious Pt/C + RuO2–assembled counterpart. The developed methodology for the fabrication of “ship-in-a-bottle” architectures may open new opportunities to low-cost, mass production of high-efficiency bifunctional oxygen electrocatalysts for a variety of renewable energy technologies and beyond.

The combined effects of the porous structure, acidity, and ion-exchange properties of zeolites and the structures of the degradation products of nitrosamines in aqueous solution on adsorption were evaluated. The degradation products of nitrosamines including the aliphatic low-molecular-weight amines methylamine, dimethylamine, ethylamine, and diethylamine and the aromatic amine aniline all exhibited significant adsorption affinities to HZSM-5 zeolites, and aliphatic low-molecular-weight amines exhibited much greater adsorption affinities to HY zeolite than to NaY and HZSM-5 zeolites, but aromatic amines exhibited little adsorption affinity to HY and NaY zeolites. The results of the pH-dependency experiments further indicated that the acidity and polarity of the adsorbates and the acidity of the adsorbents play a combinational role in determining the significance of the adsorption interactions between low-molecular-weight amines in aqueous solution and zeolites. We propose that the acid–base and electrosta...

Clubroot, caused by Plasmodiophora brassicae, has become a serious threat to canola (Brassica napus) production in western Canada. Experiments were conducted to evaluate the effect of rate of metam sodium fumigant (dithiocarbamate; sodium N-methyldithiocarbamate; trade name Vapam) and application methods including watering, soil surface covering, and soil incorporation on clubroot of canola. At higher rates (0.4–1.6 mL−1 L soil) metam sodium increased canola seedling emergence and plant health, and reduced root hair infection, gall weight and clubroot severity under greenhouse conditions. Metam sodium application improved subsequent plant growth and reduced clubroot severity, but land preparation and volume of water applied did not affect efficacy. The incorporation of metam sodium into the soil and plastic covering after application improved fumigant efficacy. The study showed that soil fumigation with metam sodium can reduce clubroot severity and improve plant health in the subsequent canola crop.

Recently, developing high-efficiency photocatalytic hydrogen generation photocatalysts and clarifying the inherent mechanism behind the enhancement of hydrogen generation activity have been the research focus. Here, we present a step-wise strategy to prepare Pt/TiO 2 /reduced graphene oxide photocatalysts and the inherent mechanism of the enhanced photocatalytic activities were systematically investigated. Experimentally, the 2 wt% rGO doped rGO/Pt-TiO 2 nanocomposites showed the superior solar-driven hydrogen generation rate (1075.68 μmol h −1 g −1 ), which was 81 times and 5 times higher than bare TiO 2 and Pt/TiO 2 samples, respectively. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectra (FT-IR) demonstrated the formation of Ti O C bonds in the hybrid, which drove the shifting upwards of the valence band edge from +2.2 eV to +1.83 eV. Furthermore, photoelectrochemical tests indicated the electron density of PTG-2 was about one order of magnitude higher than TiO 2 . Moreover, DFT calculations displayed that the bandgap had been successfully narrowed from 2.88 eV to 2.76 eV and the original blank energy region located at TiO 2 bandgap was filled with C2p orbitals, which resulted in excited electrons in TiO 2 efficiently transferring to graphene. Consequently, the DFT calculations are in good agreement with the experimental results and physical characterizations. This study affords us a rational design of a high efficiency photocatalytic system for solar energy conversion.

Metal selenides have been proposed as counter electrodes (CEs) to substitute for Pt in dye-sensitized solar cells (DSSCs) due to their good catalytic activity for the reduction of triiodide. In this paper, NiSe 2 nanoparticles were synthesized by a facile, room-temperature process and used as the CEs. In order to further enhance the photovoltaic property, graphene was introduced by facile physical mixing. Eventually, with the assistance of graphene, NiSe 2 + 6 wt% graphene CE exhibited better power conversion efficiency ( PCE ) compared with Pt CE.

In this study, removal efficiency and mechanism of four typical ARGs with two different molecular structures (i.e., cyclic (c)- and double-stranded (ds)-ARGs) by graphene oxide (GO) nanosheet were systematically investigated. The average removal of four ARGs was as high as 3.11 logs toward c-ARGs and 2.88 logs toward ds-ARGs at 300 μg/mL GO solution. The data of adsorption were fitted well with Freundlich isotherm and pseudo-second-order kinetic model. The apparent adsorption equilibrium can be obtained within 15 mins for both c-ARGs and ds-ARGs, indicating the effective removal by GO. The free-energy parameters demonstrated that the removal processes were exothermic and spontaneous. The structural differences of genetic molecular structures can be responsible for the removal discrepancy. Moreover, several removal factors containing initial ARGs concentration, pH and ion species were also investigated. The results of Raman spectra, Diffuse Reflectance Infrared Fourier Transform spectroscopy (DRIFTs) and electrochemical analysis indicated that the adsorption of ARGs by GO was mainly attributed to the oxygen containing groups and π-bonding system of GO nanosheet, which resulted in chemical binding with aromatic nucleic acid and strongly π-stacking interactions. Furthermore, a detailed verification test of real water samples was conducted and 80% of the ARGs can be removed from a natural water sample. As a result, it would be great potential to apply GO nanosheet as a novel adsorbent for effective treatment of ARG-contaminated waters.

Sudan I-IV as synthetic azo dyes have been concerned worldwide and ever caused a panic on food safety because of illegal addition into foodstuffs. In the past decades, various methods are being developed to identify and determine Sudan dyes in foodstuffs. However, relevant studies about their biogeochemical behaviors and potential environmental effects are rarely reported, although it is of great importance and necessity accounting for their potential environmental contamination from various sources. In this work, the experimental studies on adsorption behavior of Sudan I-IV acting on soil (10, 25, 50, 75, and 100 mg/L) were carried out, and their transport in soil compartments and between soil-water, and air-soil interfaces were discussed. Results showed that the amount of Sudan I-IV adsorbed on soil increased accordingly with the increasing concentration of Sudan dyes in aqueous solution, and Sudan II and IV were more likely adsorbed on the tested soils than Sudan I and III based on their maximum adsorption amount. However, for Sudan I, III, and IV, in some high concentrations (under the treatment of 75 mg/L for Sudan III, 100 mg/L for Sudan I and IV), the adsorption was significantly increased, and then came back to the "normal" level (under the treatment of 100 mg/L for Sudan III). It is expected that relevant researches on their biogeochemical behaviors in soil compartments, and between soil-water and air-soil interfaces would be concerned and addressed.

Oxygen reduction reaction (ORR) plays an important role in green energy conversion, although catalysts are necessary for overcoming its sluggish kinetic. Herein, a nanocrystal NiCo2O4/N-doped graphene composite material showing high ORR electrocatalytic activity is prepared. The resulting NiCo2O4/N-doped graphene composite (NiCo2O4-NG/C) combines the advantages of both component materials and shows enhanced ORR electrocatalytic activity (i.e., more positive peak potential and half-wave potential compared with NiCo2O4) while having higher diffusion-limited current density values (−5.7 mA cm−2, 1600 rpm), better tolerance to methanol, and improved stability than 20 wt% Pt/C. NiCo2O4 anchored on N-doped graphene are demonstrated to be nanocrystal with tiny crystalline grain (diameter

Although carbon nanomaterials have been widely used as effective nanofillers for fabrication of mixed matrix membranes (MMMs) with outstanding performances, the reproducibility of the fabricated MMMs is still hindered by the non-homogenous dispersion of these carbon nanofillers in membrane substrate. Herein, we report an effective way to improve the compatibility of carbon-based nanomaterials with membrane matrixes. By chemically conjugating the oxidized CNTs (o-CNTs) and GO using hexanediamine as cross-linker, a novel carbon nanohybrid material (G-CNTs) was synthesized, which inherited both the advanced properties of multi-walled carbon nanotubes (CNTs) and graphene oxide (GO). The G-CNTs incorporated polyvinylidene fluoride (PVDF) MMMs (GCNTs/PVDF) were fabricated via a non-solvent induced phase separation (NIPS) method. The filtration and antifouling performances of G-CNTs/PVDF were evaluated using distillate water and a 1 g/L bovine serum albumin (BSA) aqueous solution under 0.10 MPa. Compared to the MMMs prepared with o-CNTs, GO, the physical mixture of o-CNTs and GO and pure PVDF membrane, the G-CNTs/PVDF membrane exhibited the highest water flux up to 220 L/m2/h and a flux recovery ratio as high as 90%, as well as the best BSA rejection rate. The excellent performances should be attributed to the increased membrane pore size, porosity and hydrophilicity of the resulted membrane. The successful synthesis of the novel nanohybrid G-CNTs provides a new type of nanofillers for MMMs fabrication.

A feasible and green sol-gel method is proposed to fabricate well-distributed nano-particulate Fe-Ni2P incorporated in N, P-codoped porous carbon nanosheets (Fe-Ni2P@N,P-CNSs) using biomass agarose as a carbon source, and ethylenediamine tetra (methylenephosphonic acid) (EDTMPA) as both the N and P source. The doped Fe in Ni2P is essential for a substantial increase in intrinsic catalytic activity, while the combined N,P-containing porous carbon matrix with a better degree of graphitization endows the prepared Fe-Ni2P@N,P-CNSs catalyst with a high specific surface area and improved electrical conductivity. Benefiting from the specific chemical composition and designed active site structure, the as-synthesized Fe-Ni2P@N,P-CNSs manifests a satisfying catalytic performance toward both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in an alkaline solution, with low overpotential, small Tafel slope and long-term durability, relative to the counterparts (Fe-free Ni12P5/Ni2P2O7@N,P-CNSs and CNSs) with single components and even comparable to Pt/C and RuO2 catalysts. The present work broadens the exploration of efficient bifunctional oxygen electrocatalysts using earth abundant biomass as carbon sources based on non-noble metals for low cost renewable energy conversion/storage.

Graphene oxide (GO) will enter the soil environment in increasing amounts. The effects of GO on the dissipation of benzo[a]pyrene (B[a]P) from contaminated soil and their phytoremediation system have been explored in this study. B[a]P is a ubiquitous soil pollutant used as a representative indicator of polycyclic aromatic hydrocarbons. A pot experiment was performed to investigate the effects of GO or/and vegetation (Tagetes patula) on B[a]P dissipation and the associated bacterial communities in soil. The bacterial communities in soil were investigated by Illumina sequencing analysis. The presence of vegetation significantly enhanced the dissipation of B[a]P from soil. The addition of GO (100 mg/kg) significantly decreased the B[a]P dissipation. When vegetation and GO coexisted, the inhibition effects of GO on B[a]P dissipation were alleviated by vegetation. Compared with the control treatment, the presence of GO or vegetation had no significant effects on the richness and diversity of bacterial communities in B[a]P-contaminated soil. Compared with the presence of only vegetation, the richness and diversity all significantly decreased when vegetation and GO coexisted. And, vegetation had a greater influence on the bacterial community composition than GO. Vegetation alleviated the inhibition effects of GO on B[a]P dissipation and had a greater influence on the associated bacterial communities than GO. This work helps to understand the interactive effects of GO and vegetation on B[a]P dissipation and the associated bacterial communities in contaminated soil.

The environmental behaviors and risks associated with graphene oxide (GO, a popular 2D nanomaterial) have attracted considerable attention. GO released to aquatic systems will most likely interact with ubiquitous nanocolloids (Nc) in surface water. However, the effects of Nc on the fate and risk of GO remain largely unknown in water. Herein, the binding of Nc onto GO was investigated via electron microscopy, electron paramagnetic resonance, 2D correlation spectroscopy and biolayer interferometry. The results revealed that electron charge transfers, hydrophilic effects and π-π stacking contributed to a strong affinity (KD = 5.6 nM) and high adsorption capacity (159.8 mg/g) of Nc onto the GO surface. Moreover, GO nanosheets transformed to a scroll morphology or multiple GO particles bridging by Nc, which remarkably reduced the aggregation and sedimentation rates after binding with Nc. Interestingly, co-exposure with Nc greatly alleviated the toxicity (e.g., tail malformation, yolk sac edema and oxidative stress) of GO to zebrafish embryos. Morphological and structural alterations of GO after binding to Nc contributed to the mechanisms for the antagonistic effects on the zebrafish embryos toxicity. The present work provides insights into the environmental fate and risk of GO by ubiquitous Nc in natural water.

Rhizodegradation performed by plant roots and the associated bacteria is one of the major mechanisms that contribute to removal of petroleum hydrocarbons (PHCs) during phytoremediation. In this study, the pot-culture experiment using wild ornamental Hylotelephium spectabile (Boreau) H. Ohba was designed to explore responses and roles of roots, microbes, and degrading genes in the rhizodegradation process. Results showed that PHCs degradation rate by phytoremediation was up to 37.6–53.3% while phytoaccumulation accounted for a low proportion, just at 0.3–13.3%. A total of 37 phyla were classified through the high throughput sequencing, among which Proteobacteria, Actinobacteria, and Acidobacteria were the three most dominant phyla, accounting for >60% of the phylum frequency. The selective enrichment of PHC degraders with high salt-tolerance, including Alcanivorax and Bacteroidetes, was induced. Generally, relative abundance of the PHC degrading genes increased significantly with an increase in PHCs concentrations, and the gene copy number in the phytoremediation group was 1.46–14.44 times as much as that in the unplanted controls. Overall, the presence of PHCs and plant roots showed a stimulating effect on the development of specific degraders containing PHC degrading genes, and correspondingly, a biodegradation-beneficial community structure had been constructed to contribute to PHCs degradation in the rhizosphere.

The interactions between nanoparticles and humic acid (HA) are critical to understanding the environmental risks and applications of nanoparticles. However, the interactions between HA fractions and graphene oxide (GO, a popular carbon nanosheet) at the molecular level remain largely unclear. Four HA fractions with molecular weights ranging from 4.6 to 23.8 kDa were separated, and the large HA fractions presented low oxygen contents and many aromatic structures. The binding constants of the large HA fractions on GO were 2.6- to 3551-fold higher than those of the small HA fractions, while the maximum adsorption capacities of the larger HA fractions onto GO were much higher. Atomic force microscopy (AFM) found that the small and large HA fractions were spread over the center and the edge of the GO nanosheets, respectively. Density functional theory (DFT) simulation and nuclear magnetic resonance spectroscopy confirmed the above phenomena (three adsorption patterns, "vs", "ps", and "pea") and revealed that HA bonded to the GO nanosheets mainly through van der Waals force and π-π interactions. The integrating analysis of binding affinity, AFM, and DFT provides new insights into the environmental behavior of GO and the applications of GO in pollutant removal under exposure from HA.

With the wide use of graphene-like nanosheets, especially in agriculture, their release into the environment, it is crucial to grasp the fate of nanosheets in soil and minimum ecological risks. The present work discovered that leaching and migration of nanosheets (rGO) in soil is affected by soil porosity and adsorption processes. And the contents of rGO−Pd in soil layers and leachate increased and then decreased with the decreased of soil porosity. Moreover, physicochemical properties of rGO−Pd nanosheets changed by leaching processes, especially the changes of morphology, thickness and oxygen functional groups. Leaching of rGO−Pd also interfered the soil microbial homeostasis accompanied by the increase of microbial species richness and community diversity. In addition, rGO−Pd altered the usage of carbon sources by edaphon. The utilization of carbon sources by soil microbes, such as polymers, sugars, phenolic acids, carboxylic acids, amino acids, and amines, was also reduced by nanosheets. These findings provide new insights into environmental behaviors of nanomaterials and nanogeochemistry.

In the past two decades, more and more attentions have been paid to soil-derived greenhouse gases (GHGs) including carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) because there are signs that they have rising negative impacts on the sustainability of the earth surface system. Farmlands, particularly paddy soils, have been regarded as the most important emitter of GHGs (nearly 17%) due to a large influx of fertilization and the abundance in animals, plants and microorganisms. Geobacter, as an electroactive microorganism widely occurred in soil, has been well studied on electron transport mechanisms and the direct interspecies electron transfer. These studies on Geobacter illustrate that it has the ability to be involved in the pathways of soil GHG emissions through redox reactions under anaerobic conditions. In this review, production mechanisms of soil-derived GHGs and the amount of these GHGs produced had been first summarized. The cycling process of CH4 and N2O was described from the view of microorganisms and discussed the co-culture relationships between Geobacter and other microorganisms. Furthermore, the role of Geobacter in the production of soil-derived GHGs is defined by biogeochemical cycling. The complete view on the effect of Geobacter on the emission of soil-derived GHGs has been shed light on, and appeals further investigation.

Flocculants have been used to clarify water for thousands of years. However, the in situ evaluation of flocculant toxicity is difficult because flocculants usually exist as growing complex flocs which is hard to monitor. With alum (KAl(SO4)2·12H2O) as the typical flocculant, a bioelectrochemical sensor is designed to in situ detect its bacterial toxicity. The attenuation ratio of current densities linearly increased with alum concentration (R2 > 0.98) with a slope of 0.0054 A m–2 drop per mg L–1 of alum, indicating a typical toxic response of alum. Turnover and nonturnover cyclic voltammetries (CVs) revealed that the alum inhibited the electrochemical activity of bacteria rather than changing the electron transfer pathways. Alum also hindered the diffusion by flocculation at a concentration larger than 100 mg L–1, which was further confirmed by the linear decrease in viability when biofilm thickness increased. It was revealed that both inactivation of biofilm and influences on diffusion by alum can be det...

Ag/g-C3N4 composite photocatalyst, which was synthesized by thermal polymerization of melamine precursor combined with the photo-assisted reduction method, was applied as an efficient visible-light-driven photocatalyst for inactivating Escherichia coli (E. coli). The composite photocatalysts exhibited significantly enhanced photocatalytic disinfection efficiency than pure g-C3N4 powders. The mechanism of enhanced disinfection activity was systematically investigated by UV–visible diffuse reflectance spectra, photoluminescence spectra, and photo-electrochemical methods including photogenerated current densities, electrochemical impedance spectroscopy (EIS) spectra and Mott–Schottky plots. The enhanced photocatalytic bactericidal effect was attributed to the hybrid effect from Ag and g-C3N4, which resulted in enhanced adsorption of visible light, reduced recombination of free charges, rapid separation and transportation of photogenerated electrons–holes. The disinfection mechanism was studied by employing chemical scavengers and ESR technology, indicating the important role of h+ and e−. Considering the bulk availability and excellent disinfection activity of Ag/g-C3N4, it is a promising solar-driven photocatalyst for cleaning microbial contaminated water in practice.

Degradation efficiency, product distribution and reaction pathway of N-nitrosodimethylamine (NDMA) photocatalytic degradation over TiO 2 nanotube(TiNT), Au-modified TiO 2 nanotube(Au/TiNT) and TiO 2 nanopowder(TiO 2 ) were investigated to evaluate the tube effect. The results show that TiO 2 nanotube was prepared and tubular morphology was kept after Au modification. The degradation efficiencies of NDMA over TiNT and Au/TiNT are significantly higher than that over TiO 2 powder, DMA becomes to be the major product, and NO 2 − production is also detectable, which all stem from the tubular morphology of TiNT and Au/TiNT. In the presence of TiNT and Au/TiNT, the small NDMA molecules enter into the nanotube and lead to a higher concentration and a closer contact in a nanotube structure space, resulting in remarkable high degradation efficiencies of NDMA, and also initiating new photocatalytic reaction pathway derived from effectively contacts between radical intermediate and NO 2 − products in the nanotube structure. The nanotubular morphology of TiNT and Au/TiNT plays an important role in enhancing NDMA photocatalytic performances.

From eastern to western areas, per- and polyfluoroalkyl substances (PFASs) were detected at substantial levels in the outdoor dust across mainland China. Urban samples generally showed higher levels compared with those of rural samples. Compared with neutral PFASs, ionizable PFASs (C4-C12 perfluoroalkyl carboxylic acids and C4/C8 perfluoroalkyl sulfonic acids) were more abundant, with the highest total concentration up to 1.6 × 10(2) ng/g and perfluorooctanoic acid (PFOA) being a predominant analogue. Fluorotelomer alcohols (FTOHs) and polyfluoroalkyl phosphoric acid diesters (DiPAPs) were both detected in most samples with total concentrations of 0.12-32 and 0.030-20 ng/g, respectively. Perfluorooctane sulfonamidoethanols/sulfonamides (FOSE/As) were detected at low frequencies (

To study the uptake pathways of 3 main hexabromocyclododecane diastereoisomers (α-, β-, and γ-HBCDs) in wheat, four closed chambers were designed to expose wheat to HBCDs via air and/or soil for 4 weeks. The results showed that HBCDs could be absorbed by wheat both via root from soil and via leaf from air. The Rt values (ratio of HBCDs from root-to-leaf translocation to the total accumulation in leaves) ranging from 14.4 to 29.8% suggested that acropetal translocation within wheat was limited. A negative linear relationship was found between log Rt and log Kow of the HBCD diastereoisomers (p0.05). The bioconcentration factors (BCFs, (μg/g wheat tissues)/(μg/g soil)) were in the order α-β-γ-HBCD in wheat roots and stems, being negatively related to their Kow values. No such correlation was found in leaves, where the HBCDs came mainly from air distribution. The results of enantiomeric fractions indicated that the (-)-enantiomer of α- and γ-HBCDs and the (+)-β-enantiomer were selectively accumulated. Furthermore, β- and γ-HBCDs were transformed to α-HBCD in the wheat, with 0.309-4.80% and 0.920-8.40% bioisomerization efficiencies at the end of the experiment, respectively, being the highest in leaves. Additionally, no isomerization product from α-HBCD was found.