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Litter inputs are closely related to both forest productivity and nutrient cycling under climate change and local management. This study investigated the effect of litter inputs on litter decomposition, changes in litter chemistry and nitrogen (N) dynamics during eucalyptus leaf litter decomposition. Two parallel in situ litter decomposition experiments were conducted at two sites with high-quality (HQ) and low-quality (LQ) litters in a eucalyptus-dominated forest of southeast Queensland, Australia. At each site, leaf litters with either a single (SL) or double mass load (DL) of litter inputs were decomposed for 15 months. Litter mass loss, chemical composition and N content of decomposing litters were measured seasonally during the decomposition period. The chemical composition of the collected litters was determined by solid-state 13C nuclear magnetic resonance (NMR) spectroscopy. The HQ litters decomposed faster than the LQ litter, with a decomposition constant of 0.53 and 0.33 y−1 at the HQ and LQ site, respectively. Litter addition rates had no effect on litter decomposition, changes in chemical composition and N content during decomposition regardless of differences in initial litter quality. The HQ and LQ litters showed the same pattern of chemical changes during decomposition, with an increase in alkyl C and a decrease in di-O-alkyl C and aryl C. The relative intensity of O-aryl C and carboxyl C converged, while the relative intensity of di-O-alkyl C and δ15N diverged as the decomposition progressed. N immobilization during decomposition depended on litter quality, with N consistently immobilized in LQ litters over the whole decomposition period. In subtropical eucalyptus-dominated forests, the dynamics of organic C and N during litter decomposition were resistant to the increased inputs of aboveground litters. Litter chemistry of different initial qualities converged at the early stages of decomposition, and the implications of chemical convergence on the formation and stabilization of soil organic matter need to be assessed in the future.

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.

D-amino acid (DAA) an environmentally friendly biofilm inhibitor, has low efficiency for membrane biofouling control due to its instability. To address this challenge, a novel nanocomposite was prepared with DAA adhering to polydopamine (PDA)-coated halloysite nanotube (HNTs) through the interactions of H-bonding and π-π stacking between PDA and DAA. Membrane modified with such nanocomposite was fabricated via blending phase inversion, and the nanocomposite was uniformly distributed in the modified membrane matrix. In comparison with the pristine membrane, the addition of nanocomposites resulted in robust mechanical property for modified membrane with the ultimate stress and strain increased by 23.97% and 35.62%, respectively. Moreover, an excellent tradeoff between water flux (2.5 folds of pristine membrane) and selectivity was achieved, probably due to the improved membrane hydrophilicity. Meanwhile, bovine serum protein (BSA) static adsorption as well as dynamic filtration experiments exhibited excellent antifouling ability of the modified membrane. Most importantly, a superior anti-biofouling stability over a 10-day period was obtained for the membrane modified with nanocomposite, indicating that the activity of DAA to mitigate biofouling was effectively maintained. This study developed a novel and promising strategy for membrane biofouling mitigation.

The Ag/ZnO/g-C3N4 composite photocatalyst, which was synthesized by thermal polymerization of a melamine precursor combined with solvothermal reaction, was used as a visible-light-driven biocide toward Escherichia coli (E. coli). The Ag/ZnO/g-C3N4 composite displayed considerably increased visible-light-driven bactericidal activity compared to g-C3N4, Ag/g-C3N4, and ZnO/g-C3N4 powders. The photocatalytic destruction of E. coli cells was verified by fluorescence-based cell live/dead analysis and SEM. The mechanism of increased bactericidal effect was studied by UV–vis diffuse reflectance spectroscopy, photoluminescence spectroscopy, photocurrent response, and electrochemical impedance spectroscopy (EIS). The enhanced photocatalytic bactericidal effect was attributed to the matching conduction band levels of g-C3N4 and ZnO and the surface plasmon resonance (SPR) effect of Ag nanoparticles, which resulted in enhanced adsorption of visible light, reduced recombination of free charges, and rapid separation and transportation of photogenerated electrons-holes. The disinfection mechanism was investigated using different chemical scavengers and electron spin-resonance spectroscopy (ESR), and indicating the important role of h+ and H2O2. Furthermore, taking into account the bulk availability and better bactericidal effect of Ag/ZnO/g-C3N4, this work provides a new pathway to develop advanced materials for water disinfection.

As an abundant and biologically active element, sulfur has been applied in various fields. Through the nanotechnology method, nanosulfur is synthesized with the merits of size effects. Differentiat...

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.

This work was financially supported by the National Natural Science Foundation of China (NSFC Nos. 21875112 and 21576139), the National and Local Joint Engineering Research Center of Biomedical Functional Materials, and the Priority Academic Program Development of Jiangsu Higher Education Institutions.

Soybean (Glycine max) acreage on the Canadian Prairies has increased rapidly in recent years. Production has expanded into semiarid regions where irrigation and drainage problems often result in the accumulation of salts in the soil. Fusarium avenaceum and Rhizoctonia solani are the two dominant pathogens in the disease complex that cause root rot and seedling blight of legume crops on the Canadian Prairies. The effects of F. avenaceum or R. solani in combination with soil salinity on soybean root rot were evaluated under greenhouse and mini-plot conditions. As expected, inoculation with F. avenaceum or R. solani consistently reduced seedling emergence and increased root rot severity in soybean. At high soil electrical conductivity values and inoculum densities, seedling emergence decreased and root rot severity increased in soybean in both trials with F. avenaceum and R. solani. Twenty short-season soybean cultivars that were well suited for production in Alberta were evaluated for their reactions to inoculation with F. avenaceum or R. solani in a saline soil (21.1 dS m−1). High seedling emergence was observed for cultivars 900Y61, P002T04R, 900Y01, TH27005RR, P001T34R, and 900Y81 in the non-inoculated control, for P002T04R and 900Y61 in the F. avenaceum treatment, and for 900Y61, 900Y81, and 900Y71 in the R. solani treatment. Root rot severity was low for cultivars NSC Portage and 900Y61 in the non-inoculated control and P002T004R in the F. avenaceum treatment. The cultivar 900Y61 also consistently had lower disease severity over the trials in the mini-plot test.

Soybean (Glycine max (L.) Merr.) has been a commercial oilseed crop in Canada since the 1920s. The production of soybean rapidly increased from 2004 to 2016 in Alberta and Manitoba. Root rot disease caused by the oomycete genus Pythium was observed from 105 fields in 2015 and 2016 in southern Alberta and Manitoba. In the present study, a total of 97 isolates of Pythium were recovered from the root tissues of soybean seedling collected from those fields. Identification of the Pythium species was achieved by examining their morphological features and sequences analysis of internal transcribed spacers (ITS) and cytochrome oxidase subunit 2 gene (Cox II). Nine species of Pythium were identified, with Pythium violae as the predominant species (27 out of 97, 27.8%), followed by P. intermedium (21), P. irregulare (16), P. sylvaticum (12), P. recalcitrans (8), P. ultimum (8), P. heterothallicum (3), P. conidiophorum (1) and P. macrosporum (1). This is the first report of P. conidiophorum, P. recalcitrans and P. violae on soybean in Canada. All the Pythium isolates except three isolates (S2d of P. violae, S29a and S29b of P. heterothallicum) were highly virulent on soybean, causing root rot disease symptoms.

The quantity and quality of litter inputs to forest soils are likely to be changed as a result of the climate change and human disturbances. However, the effects of changed litter inputs on soil labile carbon (C) and nitrogen (N) pools still remain unclear. A 15-month in situ field experiment was conducted within both high and low litter quality site in a eucalyptus-dominated native forest of Queensland, Australia. Three rates of litter inputs were applied, including (i) no litter (NL); (ii) single litter (SL), representing the average condition of the surrounding forest floor; and (iii) double litter (DL). Water-extractable organic C (WEOC) and total N (WETN), hot water-extractable organic C (HWEOC) and total N (HWETN), microbial biomass C (MBC), and N (MBN) were analyzed in the 0–5-cm soil layer seasonally. Litter input rates had no significant effects on litter decomposition at both sites (P > 0.05). After 15-month of decomposition, mean litter mass loss was 46.3% and 31.2% at the HQ and LQ sites, respectively. Changed litter quantity had no significant effects on any of the soil labile C and N pools, regardless of litter quality. However, soil labile C and N pools significantly varied with sampling times, and the samples of different sampling times were clearly separated at both sites according to the redundancy analysis (RDA). WEOC peaked in summer, declined in autumn and winter, and increased again in spring, while the concentrations of HWEOC and MBC peaked in the winter period. The seasonal trends of MBN were opposite to the trends of WETN, which might be due to the temporal partitioning of N between plants and microbes. The findings indicated that soil labile C and N pools in the eucalyptus-dominated forest of subtropical Australia were resistant to a short-term change in aboveground litter inputs. Future research should expand on these findings by keeping observing over a longer time period and considering the influence of changed belowground litter inputs.

In this work, activated carbon with ZnO laden on the surface was prepared by ZnCl2-one-step activation of different types of biomass (corn straw, bamboo powder and sawdust) and employed for mercury removal in the coal gas. During the activation, a part of ZnCl2 is converted into ZnO and laden on activated carbon, which greatly promotes the mercury removal performance with the presence of H2S. The ZnO content varies greatly with the content of SiO2 in the biomass due to its inactivation of ZnO and formation of Zn2SiO4. Carbonyl, which is important to mercury removal is largely retained after the activation at 500 °C and the amount of carbonyl seems to be positively correlated with the specific surface area (related to the lignin content). The temperature programmed desorption method was applied to further analyse the mercury adsorption in the coal gas. The results showed that ZnO and carbonyl play an important role in mercury removal, while the physisorption is not significant and only accounts for approximately 7% at 130 °C. The mechanism study showed that ZnO serves as a catalytic active site and catalyses the Hg0 into HgS with the presence of H2S. While the C O group of carbonyl acts as adsorption sites and turns into C O after the adsorption. This study provided a promising preparation method of mercury sorbents in the coal gas, and the influence of surface functional groups was also investigated in detail.

Lakes are critical for biogeochemical and ecological processes and are sensitive and vulnerable to anthropogenic disturbances, but how and to what extent human activities disturb the biodiversity in lakes remain unknown. Here, we showed the microbial diversity in 46 lakes and assessed the influence of 27 anthropogenic factors. We found that the economic level (e.g., per capita gross domestic product) was strongly negatively correlated (r = -0.97) with bacterial diversity but positively correlated (r = 0.17) with fungal diversity in lakes. The composition of the microbial community significantly changed with increasing economic level. Bacteria are more sensitive than fungi to anthropogenic impacts. Expanding the population size and increasing the economic level may promote the development of fungal diversity but inhibit bacterial diversity. Air quality, urbanization and ozone were negatively correlated with bacterial diversity, and fisheries had a negative correlation with fungal diversity. The anti-interference ability of lake microorganisms in the middle economic level zones (45,000-90,000 yuan/person) was stronger than that in high-level (90,000 yuan/person) and low-level (45,000 yuan/person) economic zones. Overall, our investigation provides national-scale evidence that changes in the microbial diversity in lakes were related to economic levels.

The combined bioremediation of microorganisms and plant roots is an environmentally friendly soil remediation technology with the application prospect. The inefficiency of electron transfer hinders the decomposition of reluctant petroleum hydrocarbons and the further absorption by plant roots in plant-rhizosphere microbial electrochemical system. A conductive network of extracellular electron transfer was constructed in this study by the combination of magnetite and external electrode, committed to strengthening the process of Direct interspecific electron transfer (DIET), Dissimilation iron reduction (DIR), and long-distance electron transport. The microbial conversions of C, N, and Fe related to the hydrocarbon removal were investigated in the compound remediation system (Fe + MEC). Compared with the control group (PCK), an increased 174–232% of Total petroleum hydrocarbons (TPHs) was removed from Fe + MEC, accompanied by the generation of bio-current. Synchronously, the reduction of iron oxide (mainly DIR) and nitrogen (mainly denitrification) was promoted due to the rapid transfer of extracellular electrons. A reinforced synergistic network of the potential degradation, denitrification, and iron-reducing/exoelectrogenic bacteria was constructed in the compound system, which may be connected through the magnetite-mediated electron transport chain. The results in this study provide an insight into the impasse overcoming of inefficient electron transfer during the remediation of organic contaminated soil.

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.

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.

Mitigating membrane fouling extensively occurred in membrane-based water treatment techniques in an efficient and durable way is a pressing challenge. The novel electro-assisted membrane coupling technology showed great potentials for tackling the problem. Foulants like charged natural organic matter, colloids and bacteria can be successfully repelled from membrane surface in the presence of electric field, contributing to less adoption, accumulation, and blocking. More importantly, the inactivation of microorganisms induced by electric field played a significant role in inhibiting the formation of the stubborn biofilm, which showed distinct and excellent advantages over other membrane fouling control approaches like surface hydrophilic modification, chemical cleaning, and pretreatment optimization. This thorough and long-term effective coupling means will actually open a new sight for membrane fouling mitigation fields. Herein, we reviewed the configuration of direct current (DC) membrane coupling technology to control membrane fouling, fouling alleviating mechanisms, and membrane filtration performances of DC electric field membrane coupling process. Additionally, some potential drawbacks and corresponding strategies were also discussed; hopefully to supply some viewpoints for prospective developments in membrane fouling mitigation fields.

The rational design of cost-effective and highly efficient catalysts for the oxygen evolution reaction (OER) is vastly desirable for advanced renewable energy conversion and storage systems. Tailoring the composition and architecture of electrocatalysts is a reliable approach for improving their catalytic performance. Herein, we developed hierarchical ultra-thin Co nanosheets coupled with N-doped carbon plate (Co-NS@NCP) as an efficient OER catalyst through a feasible and easily scalable NaCl template method. The rapid dissolution-recrystallization-carbonization synthesis process allows Co nanosheets to self-assemble into plenty of secondary building units and to distribute uniformly on N-doped carbon plate. Benefitting from the vertically aligned Co nanosheet arrays and hierarchical architecture, the obtained Co-NS@NCP possess an extremely high specific surface area up to 446.49 m2 g−1, which provides sufficient exposed active sites, excellent structure stability, and multidimensional mass transfer channels. Thus, the Co-NS@NCP affords remarkable electrocatalytic performance for OER in an alkaline medium with a low overpotential of only 278 mV at 10 mA cm−2, a small Tafel slope, as well as robust electrocatalytic stability for long-term electrolysis operation. The present findings here emphasize a rational and promising perspective for designing high-efficiency non-precious electrocatalysts for the OER process and sustainable energy storage and conversion system.

Soils are a repository for polychlorinated biphenyls (PCBs). A pot incubation experiment was performed with four soils (black soil, paddy soil, oasis soil, and fluvo-aquic soil) treated with Aroclor 1242 to achieve PCB concentrations of 5 mg kg−1. The soil enzyme activities of protease, phosphatase, catalase, dehydrogenase, and laccase were determined by spectrophotometry. The soil bacterial communities were investigated using Illumina sequencing analysis. The results showed that the characteristics of the test soils varied among the soil types. The fluvo-aquic soil had the greatest PCB dissipation rate (86.41%), followed by the oasis (79.31%), paddy (56.09%), and black (50.65%) soils. The soil pH, cation exchange capacity, soil organic matter content, and particle diameter played significant roles in PCB dissipation from soils. The soil type had a greater influence than PCB contamination on the soil enzyme activities and bacterial communities (alpha diversity, community structure, and composition). Among the four soils, the bacterial communities of the fluvo-aquic soil were the most susceptible to PCB contamination. However, the bacterial communities of the black soil were not changed by PCB contamination.

Objective: Mast cells-derived extracellular vesicles (EVs) play vital roles in various physiological and pathophysiological conditions. However, the cargoes of mast cells-derived EVs in asthma have not been established. Here, we set to identify the role of microRNA-21 (miRNA-21) from mast cells-derived EVs in ozone- and lipopolysaccharide (LPS)-induced mouse airway epithelial cells (MIC-iCell-a006 cells) and asthmatic mice. Methods: After ozone or LPS treatment, MIC-iCell-a006 cells were subjected to a microarray analysis to screen differentially expressed miRNAs, and then co-cultured with EVs. miR-21 was silenced in cells, followed by CCK-8, scratch, and Transwell assays. Mice were challenged with ovalbumin, and antioxidant enzymes and inflammatory cell infiltration were assessed after EVs and miR-21 inhibitor treatments. The relation between miR-21 and DDAH1 was evaluated by Dual-luciferase assay, and changes in Wnt/β-catenin pathway related proteins were examined by western blot. Finally, the involvement of the DDAH1/Wnt/β-catenin axis in miR-21-mediated oxidative stress and inflammation was verified by rescue experiments. Results: miR-21 expression was upregulated in MIC-iCell-a006 cells induced by ozone or LPS. miR-21 was enriched in mast cells-derived EVs, and EVs increased miR-21 expression in MIC-iCell-a006 cells. miR-21 inhibitor increased cell activity and alleviated oxidative stress and inflammation. In asthmatic mice, miR-21 expression was increased, and EVs decreased antioxidant enzymes and increased inflammatory cells, whose effects were reversed by miR-21 knockdown. miR-21 targeted DDAH1 to mediate the Wnt/β-catenin signaling, and down-regulation of DDAH1 inhibited the action of miR-21 inhibitor. Conclusion: The miR-21 secreted from mast cells-derived EVs promotes oxidative stress and inflammatory responses in asthmatic mice via the DDAH1/Wnt/β-catenin signaling axis.

Chromium (Cr) is one of the most severe heavy metal contaminants in soil, and it seriously threatens ecosystems and human health through the food chain. It is fundamental to collect toxicity data of Cr before developing soil quality criteria/standards in order to efficiently prevent health risks. In this work, the short-term toxic effects of Cr(VI) and Cr(III) on the root growth of eleven terrestrial plants were investigated. The corresponding fifth percentile hazardous concentrations (HC5) by the best fitting species sensitivity distribution (SSD) curves based on the tenth percentile effect concentrations (EC10) were determined to be 0.60 and 4.51 mg/kg for Cr (VI) and Cr (III), respectively. Compared to the screening level values worldwide, the HC5 values in this study were higher for Cr(VI) and lower for Cr(III) to some extent. The results provide useful toxicity data for deriving national or local soil quality criteria for trivalent and hexavalent Cr.

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.

Soil is an essential part of our ecosystem and plays a crucial role as a nutrient source, provides habitat for plants and other organisms. Overuse of antibiotics has accelerated the development and dissemination of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs). ARB and ARGs are recognized as emerging environmental contaminants causing soil pollution and serious risks to public health. ARB and ARGs are discharged into soils through several pathways. Application of manure in agriculture is one of the primary sources of ARB and ARGs dissemination in the soil. Different sources of contamination by ARB and ARGs were reviewed and analyzed as well as dissemination mechanisms in the soil. The effects of ARB and ARGs on soil bacterial community were evaluated. Furthermore, the impact of different sources of manure on soil microbial diversity as well as the effect of antibiotics on the development of ARB and ARGs in soils was analyzed. Human health risk assessments associated with the spreading of ARB and ARGs in soils were investigated. Finally, recommendations and mitigation strategies were proposed.

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.

At present, the uptake and accumulation of nanoplastics by plants have raised particular concerns. However, molecular mechanisms underlying nanoplastic phytotoxicity are still vague and insufficient. To address this scientific gap, we analyzed the transcriptome response of hydroponically grown wheat (Triticum aestivum L.) to polystyrene nanoplastics (PSNPs) (100 nm) by integrating the differentially expressed gene analysis (DEGA) and the weighted gene correlation network analysis (WGCNA). PSNPs could significantly shape the gene expression patterns of wheat in a tissue-specific manner. Four candidate modules and corresponding hub genes associated with plant traits were identified using WGCNA. PSNPs significantly altered carbon metabolism, amino acid biosynthesis, mitogen-activated protein kinase (MAPK) signaling pathway-plant, plant hormone signal transduction, and plant-pathogen interaction Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. In addition, some Gene Ontology (GO) terms associated with the metal ion transport were further screened. These findings shed new light on the phytotoxic mechanism and environmental implication behind the interaction of nanoplastics and crop plants, and advance our understanding of the potential adverse effect induced by the presence of nanoplastics in agricultural systems.

Zeolitic imidazole frameworks (ZIFs) have attracted a considerable amount of attention for use in environmental applications (e.g., pollutant adsorption and photocatalysis in water treatments). The environmental stability and toxicity of ZIFs are key prerequisites for their practical applications, but information about these factors is largely lacking. The present work finds that pristine ZIFs (ZIF-8 and ZIF-67) photodegrade from frame structures into two-dimensional nanosheets and are oxidized to zinc carbonate (ZIF-8) and Co3O4 (ZIF-67) under visible-light irradiation. The photoinduced electrons, holes and free radicals promote dissolution of the metal cores and organic ligands, leading to collapse of the frame structure. The photodegradation of ZIF-8 alleviates developmental inhibition, oxidative stress, plasmolysis, and photosynthetic toxicity, while the photodegradation of ZIF-67 aggravates nanotoxicity. The integration of metabolomics and transcriptomics analysis reveals that unsaturated fatty acid biosynthesis and metal ion-binding transcription contribute to the altered toxicity of ZIF photodegradation. These findings highlight the roles of photodegradation in structural transformation and alteration of the toxicity of ZIFs, alarming the study of pristine metal-organic frameworks (MOFs).

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.

Manure, soil, and vegetable samples were collected from different-sized livestock farms in Xinxiang, China. The residues of sulfadiazine, sulfamonomethoxine, and sulfamethoxazole were analyzed by high-performance liquid chromatography. The results indicated that the concentration ranges of the three total sulfonamides in manure, soil, and vegetables were 10.13–566.23 µg kg−1, 7.60–176.26 µg kg−1, and 0–32.70 µg kg−1, respectively. The mean concentrations were 219.71 µg kg−1, 70.73 µg kg−1, and 7.08 µg kg−1 for manure, soil, and vegetables, respectively. The mean concentrations in soil were lower than the ecotoxic effect trigger value (100 µg kg−1), indicating a low risk for organisms in soil. The concentrations of the three sulfonamides varied significantly in different types of vegetables and all were lower than the acceptable daily intake value (50 µg (kg day)−1). However, the potential ecotoxicity and danger to human and animal health via accumulation of the antibiotic in the food chain cannot be ignored.

Predicting the biological responses to engineered nanoparticles (ENPs) is critical to their environmental health assessment. The disturbances of metabolic pathways reflect the global profile of biological responses to ENPs but are difficult to predict due to the highly heterogeneous data from complicated biological systems and various ENP properties. Herein, integrating multiple machine learning models and metabolomics enabled accurate prediction of the disturbance of metabolic pathways induced by 33 ENPs. Screening nine typical properties of ENPs identified type and size as the top features determining the effects on metabolic pathways. Similarity network analysis and decision tree models overcame the highly heterogeneous data sources to visualize and judge the occurrence of metabolic pathways depending on the sorting priority features. The model accuracy was verified by animal experiments and reached 75%-100%, even for the prediction of ENPs outside of databases. The models also predicted metabolic pathway-related histopathology. This work provides an approach for the quick assessment of environmental health risks induced by known and unknown ENPs.

Background: In the case of most popularly engineered nanomaterials (e.g., transition-metal dichalcogenide (TMDCs) nanosheets), direct exposure toxicities are investigated extensively to understand the effect on specific cells and organs; however, there has been limited focus on their potential bystander effects. Bystander effects in biological systems are the responses shown by nontargeted neighboring cells or tissues, and critical to the bio-nano interface interactions. In addition to direct effects, bystander effects also determine the design, applications and safety of nanomaterials, although the related information of bystander effects remain largely unknown.Results: A coculture system of A549 and THP-1 was established to mimic the lung microenvironment to study the bystander effects of WS2 nanosheets (representative TMDCs nanosheets) on microenvironment macrophages during the inhalation exposure or the nanomaterial biomedical application in the lung. Lung cells exposed to WS2 nanosheet resulted in an increase in reactive oxygen species and the depolarization of mitochondrial membrane potential in neighboring macrophages. Bystander exposure also induced macrophage polarization toward the anti-inflammatory M2 phenotype, which is adverse to disease therapy. Metabolomics showed that WS2 nanosheets disturbed the energy metabolism and amino acid metabolism of macrophages, consistent with the metabolic characteristics of M2 macrophages. Nitric oxide-transforming growth factor-β1 played an important mediator in the bystander effects. Importantly, WS2 nanosheet bystander exposure affected macrophage phagocytosis and migration and altered the macrophage immune response to environmental endotoxin.Conclusion: This study demonstrated that WS2 exposed lung cells would elicit bystander effects on surrounding macrophage cells, which weaken the immune response of surrounding macrophage cells. This study improves the current understanding of bio-nano interactions and highlights the importance of bystander effects and neighboring cell responses, allowing us to use the maximum benefits of nanomaterials while limiting their adverse bystander effects.

Background: The CdSe nanorod as a one-dimensional nanostructure has an excellent performance in photoelectric conversion, biological labeling and environmental protection. Thus, it is crucial to investigate its potential adverse health effects at an early stage. Methods: Sprague-Dawley (SD) male rats were exposed to 15 mg/kg CdSe and 200 mg/kg procyanidine (OPC) for 30, 60 and 90 days. Lung tissues were collected on days 30, 60 and 90. Oxidation damages, histopathological analysis, transmission electron microscopy and hydroxyproline level were measured. Results: The lung tissue would be the main target organ after CdSe nanorods entering into biological bodies. Pulmonary instillation of CdSe nanorods could decrease vitality of T-SOD and T-AOC in lung tissues of a rat, increase MDA and hydroxyproline levels and lipid peroxidation products, induce mitochondrial cristae broken and vacuolization, cause inflammatory responses, and finally induce pulmonary fibrosis. The oral administration of procyanidinere could significantly increase the content of antioxidant enzymes, scavenge free radicals, reduce the lipid peroxidation and have protective effects on CdSe nanorods-induced pulmonary fibrosis. Conclusions: CdSe nanorods could induce an extensive inflammatory response, elevate ROS, induce pulmonary fibrosis and reveal time accumulation appearance. OPC has a protective effect on lung injury induced by CdSe nanorods, which might be related to anti-oxidative and anti-inflammatory properties.

Since 1970s, an increasing attention has been paid to land degradation worldwide (FAO, 1971; Zhou et al., 2017). Generally speaking, the connotation of land degradation commonly refers to the destroy of ecological balance, and the decline of soil quality and environmental capacity (regeneration, and carrying capacity), and could be categorized as soil erosion, land desertification, soil salinization-alkalization, land impoverishment, land contamination, land destruction according to their reasons (water/wind erosion, deforestation / overgrazing, unreasonable irrigation, inadequate fertilizer, pollution, mineral resources exploitation) (Liu, 1995; Zhou & Huang, 2001). The various related theories have been developed to evaluate the land degradation, such as global assessment of human-induced soil degradation (GLASOD), the assessment of the status of human-induced soil degradation in South and Southeast Asia (ASSOD), and the theory put forward by the Moscow State University and Russia Academy of Science (RUSSIA) (Sun et al., 2001). For each type of land degradation, it has various indicators and varied in different countries and regions (Morales & Zuleta, 2019).Human activities are recognized as the major reason of land degradation, and countermeasures for effective prevention and treatment of land degradation are developed accordingly, including the formulation of laws and policies (Liu, 1995; Sun et al., 2001). Soil-environmental criteria are multi-objective functions with the range of values based on scientific research on relationships between soil pollutant concentrations and ecological risk or human health effects (Zhou et al., 2007). Compared with soil-environmental standards, they do not consider economic or technological factors and are not mandatory, but are the data foundations and scientific bases for development of soil-environmental standards (Zhou et al, 2017; Teng & Zhou, 2018). Currently, many countries and regions have developed various soil-environmental quality standards to meet the demand for soil management, such as screening levels, and intervention values. Generally, the methodological and deriving researches of soil-environmental criteria were far from adequacy for the development and revision of their standards, and further to serve the prevention and treatment of land degradation. ReferencesFood and Agriculture Organization of the United Nations (FAO) (1971). Land Degradation. Soils Bulletin 13, Rome, 1091, 1-10.Liu, H. (1995). Types and characteristics of land degradation and countermeasures in China. Resources Science, 4, 26-32.Morales, N. S., & Zuleta, G. A. (2019). Comparison of different land degradation indicators: Do the world regions really matter? Land Degradation & Development, 1-13.Sun, H., Zhang, T. L., & Wang, X. X. (2001). Land Degradation and its evaluating methodology. Agro-environmental Protection, 20(4), 283-285.Teng, Y., & Zhou, Q. X. (2018). Conversion relationships between environmental quality criteria of water/air and soil. Science China-Earth Sciences, 61(12), 1781-1791.Zhou, Q. X., & Huang, G. H. (2001). Environmental Biogeochemistry & Global Environmental Changes. Beijing, China: Science Press.Zhou, Q. X., Luo, Y., & Zhu, L. Y. (2007). Scientific research on environmental benchmark values and revision of national environmental standards in China. Journal of Agro-Environment Science, 26(1), 1-5.Zhou, Q. X., Teng, Y., & Liu, Y. (2017). A study on soil-environmental quality criteria and standards of arsenic. Applied Geochemistry, 77, 158-166.

Emerging transition-metal dichalcogenide (TMDC) nanosheets, such as WS

Understanding the roles of the properties of nanomaterials in biological interactions is a key issue in their safe applications, but the surface atomic arrangement, as an important property of engineered nanomaterials (ENMs), remains largely unknown. Herein, the interfacial interactions (affinity sites and intensity) between monolayer MoS2 and zebrafish embryos mediated by 1 T phase surface atomic arrangement (octahedral coordination) and the 2H phase surface atomic arrangement (triangular prism coordination) MoS2 nanosheets were studied. 1 T-MoS2 first bound to phosphate and then proteins on the chorion, while the adhesion of 2H-MoS2 occurred in the opposite order. The binding affinity of 2H-MoS2 with embryos was higher than that of 1 T-MoS2, and the former material changed the protein structure from β-sheets to turns and bends and random coils. Compared to 1 T-MoS2, 2H-MoS2 more readily entered embryos, which was facilitated by caveolae-mediated endocytosis, and caused higher developmental toxicity. Furthermore, metabolic pathways related to amino acid and protein biosynthesis and energy metabolism were affected by the nanomaterial surface atomic arrangements. The above results provide insights into the designs, applications and risk assessments of nanomaterials by the surface atomic arrangement regulation.

The conversion study on the environmental quality criteria between water/air and soil is the need to carry out research on soil-environmental quality standards in an all-round way, and also the demand for solving emerging problems in this field using the system dynamic and the overall view. Carrying out this study is of practical significance and theoretical values in the face of formulation and revision of soil-environmental quality standards in China. Firstly, the theoretical basis and relative models of soil-water and soil-air systems were expounded, respectively. And on this basis, a preliminary conceptual model about the conversion was constructed. After that, the current worldwide environmental quality criteria/standards for soil, water and air media were introduced based on their types, concerned pollutants and hierarchical classification, and their variation were also analyzed briefly. Particularlly, the key points for the conversion of environmental quality criteria between soil and water and/or between soil and air were discussed, respectively, while combined with the relative researching results. Finally, this conversion study was commented and prospected.

Norfloxacin (NFLX) is a synthetic antibiotic widely used in the treatment of infectious diseases. In this work, the performance of microbial fuel cells (MFCs) toward NFLX degradation, electricity production and the antibiotics resistances genes (ARGs) generation was investigated. NFLX degradation efficiency and COD removal reached 65.5% and 94.5% respectively. The increase in NFLX concentration (128 mg/L) had no significant influence on NFLX degradation efficiency, COD removal and MFCs voltage output while the electricity was successfully generated. The quantitative polymerase chain reaction (qPCR) indicated low absolute abundances of ARGs (mdtk, mdtm, and pmra) compared with the traditional wastewater treatment plants (WWTPs). Anodic bacteria can survive in the presence of high NFLX concentration and sustain its degradation and electricity production. In terms of NFLX degradation, COD removal, diminished ARGs generation and simultaneous energy production, MFC seems to be a promising technology for antibiotics wastewater treatment with a potential to overcome the ARGs challenge.

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.

Previous studies have shown that co-catalysts play a pivotal role for improving both the activity and reliability of semiconductors in photocatalytic hydrogen production, however, designing highly efficient and cost-effective co-catalysts to replace expensive and rare metals is still a big challenge. In this work, DFT (density functional theory) is utilized to guide the application of CoP NWs (nanowires) as an earth-abundant co-catalyst for photocatalytic hydrogen production. Metallic 1D CoP NWs is rationally integrated with Zn0.5Cd0.5S solid solution semiconductor for the first time, to induce a remarkably improved photocatalytic hydrogen production activity of 12,175.8 μmol h−1 g−1, which is 22 times higher than that of the pristine Zn0.5Cd0.5S. This outstanding activity benefits from the collaborative advantages of excellent metallic conductivity and the rigid 1D nanostructure of CoP NWs. Moreover, the mechanism investigations demonstrate that this excellent activity arises from the strong electronic coupling, favourable band structure, highly efficient charge separation and migration based on the powerful characterizations, such as time-resolved PL decay spectra and photoelectrochemical methodology. This work brings new opportunities to employ 1D co-catalysts on photocatalysts for improving the catalytic activities in hydrogen production from water.