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Microplastics/nanoplastics (MNPs) pollution in different environmental media and its adverse effects on organisms have received increasing attention from researchers. This paper compares the effects of natural concentrations of three different sizes (20 nm, 200 nm, and 2 μm) of MNPs on Vallisneria natans and sediments. MNPs with smaller sizes adhere more readily to V. natans roots, further promoting root elongation. In addition, the larger the particle size of MNPs, the higher the reactive oxygen species level in the roots, and the malondialdehyde level increased accordingly. In the sediment, 20 nm, and 200 nm MNPs increased the activity of related enzymes, including acid phosphatase, urease, and nitrate reductase. In addition, the dehydrogenase content in the treated sediments increased, and the content changes were positively correlated with the size of MNPs. Changes in microorganisms were only observed on the root surface. The addition of MNPs reduced the abundance of Proteobacteria and increased the abundance of Chloroflexi. In addition, at the class level of species composition on the root surface, the abundance of Gammaproteobacteria under the 20 nm, 200 nm, and 2 μm MNP treatments decreased by 21.19%, 16.14%, and 17.03%, respectively, compared with the control group, while the abundance of Anaerolineae increased by 44.63%, 26.31%, and 62.52%, respectively. These findings enhance the understanding of the size effects of MNPs on the roots of submerged plants and sediment. [Display omitted] • MPs can stimulate root growth more than NPs. • MNPs of 2 μm elicit more oxidative stress in roots. • MNPs with smaller size adhere more to the V. natans roots. • MNPs mainly affect the microbial community on the root surface. • MNPs can enhance the enzyme activities of sediment. [ABSTRACT FROM AUTHOR]

Harvesting harmful algal blooms is useful for treating eutrophicated water, but the effect of harvest intensity on aquatic organisms has not been reported. This study investigated the biological effects of algal harvest on submerged macrophytes and leaf biofilms. Harvesting changed the content of total dissolved phosphorus, ammonia nitrogen and dissolved oxygen in water, and suitable harvest intensity (70%) can reduce the content of microcystin-LR. Meanwhile, lower levels of malondialdehyde, glutathione, superoxide dismutase, and catalase in plants, as well as the growth of submerged macrophytes, also indicated that the optimal harvest intensity was 70%. Different harvest intensities changed the content of polysaccharide and protein in biofilms, as well as the abundances and structure of the microbial community. Moreover, the reduction in N-acylated-L-homoserine lactone content in biofilms indicated that different intensities of algal harvest induced structure alternations of biofilm and affected the ecological functions. This work contributes to understanding the ecological impact of algal harvest and provides a more appropriate harvest intensity for practical applications. [Display omitted] • Algal harvest intensity over 70% can reduce the content of microcystin-LR. • Extracellular polymeric substance contents in biofilms increased with the decreased harvest intensity. • Algal harvest induced function changes of biofilms by affecting the N-acylated-L-homoserine lactones signals. • The appropriate harvest intensity for plant growth was 70%. [ABSTRACT FROM AUTHOR]

This experiment prepared magnetic composite siderophores (DMPs) with strong magnetism, excellent adsorption capacity, and high specific surface area. Exploring the synergistic effect of magnetic nanoparticles and siderophores on Microcystis aeruginosa growth under iron-deficient condition, by utilizing the characteristics of the three-layer core-shell structure of DMPs. This study elucidated the potential mechanism by which DMPs promote the cyanobacterial growth through physiological indicators and transcriptome analysis. On the experiment's final day, cell density in DMPs treatment group at 2, 4, and 8 mg/L were 1.10, 1.14 and 1.16 times higher than those in the control group (Ct), respectively. Similarly, chlorophyll and photosynthetic efficiency results showed improved algae growth with increasing DMPs dosage. The microcystin content in DMPs experimental groups at low, medium, and high concentration were 0.91, 0.86, and 0.83 times that of Ct, indicating alleviation of iron deficiency stress. Additionally, based on extracellular polymers, intracellular and extracellular siderophores, and visualization techniques, DMPs nanoparticles captured free iron sources in the environment, promoting algae growth by entering algal cells and facilitating the uptake and utilization of free iron ions from the solution. During the experiment, the iron uptake and transport genes (feoA and feoB) were significantly upregulated, whereas the algal siderophore synthesis gene (pchF) and the TonB-dependent transport system gene (TonB_C) were significantly downregulated, suggesting heightened activity in intracellular iron uptake and transport. This indicates an abundance of intracellular iron, eliminating the need for secrete siderophores to overcome iron deficiency. Microcystis aeruginosa increased iron bioavailability by using iron transported through DMPs in the environment while internalizing these DMPs. This study explored the mechanism of this synergistic effect to boost algal growth, and provided new ideas for elucidating the mechanism of cyanobacterial bloom outbreaks as well as the innovative application of biotechnology. [Display omitted] • Deepening the interaction with M. aeruginosa through modifying siderophores. • The mechanism of DMPs promoting algal growth via transcriptomics. • DMPs facilitated algae to acquire free iron and were internalized by algae. • High-dose DMPs boosted photosynthesis, glycolysis and protein synthesis in algae. [ABSTRACT FROM AUTHOR]

Perfluorooctane sulfonate (PFOS) is an accumulative emerging persistent organic pollutant that coexists with copper (Cu) in aquatic environments and is a severe threat to human health. PFOS has genotoxicity, male reproductive toxicity, neurotoxicity, developmental toxicity and endocrine disrupting effects, and is considered to be a kind of environmental pollutant with systemic multi-organ toxicity. However, the combined effects of PFOS and Cu on aquatic organisms have not been analyzed previously. In this study, we investigate the response of Vallisneria Natans (V. natans) and biofilms to single and combined treatments of PFOS and Cu at environmental concentrations (1.0, 10.0, and 100.0 μg·L−1). Results indicate that single and combined treatment triggered the reactive oxygen species (ROS) metabolism with increased activities of GSH, MDA, CAT, TSOD and an antagonistic joint toxicity. Meanwhile, transcriptomic analyses showed that the peroxidase (PER), 9 glutaredoxin (GRX), and 39 glutathione S-transferase (GST) expression of genes related to ROS detoxification was up-regulated. In addition, single and combined exposure induced the up-regulation of the transport channel genes which encode aquaporins, rapid-type anion channels, and copper-exporting P-type ATPase transporters, promoting the uptake of PFOS and Cu in V. natans , Enhancing detoxification and mitigating the effects of Cu and PFOS exposure. Moreover, PFOS and Cu changed the structural characteristics of extracellular polysaccharides in biofilms, synthesizing large amounts of β- D -glucopyranose PS, α- D -glucopyranose PS. And the community diversity and species evenness changed, with Rhizobiaceae , Chloroplast , and Weeksellaceae being the dominant phylum. This study provides insights into the molecular mechanism of joint toxicity of PFOS and Cu by Transcriptomics and PCR analysis on the submerged macrophyte and their periphyton biofilms. [Display omitted] • Toxicity of PFOS and Cu mixture on V. natans was antagonistic. • PFOS and Cu triggered the transporter-mediated passive process. • β- D -glucopyranose PS was the dominant EPSs in biofilms with Cu exposure. • PFOS triggered more α- D -glucopyranose PS generated in biofilms. • GSEA was first reported for analysis of the joint toxicity in submerged macrophyte. [ABSTRACT FROM AUTHOR]

In this study, thermophysical and mechanical tests were conducted on sandstone samples from room temperature to 1000 °C. Based on the test results, the thermophysical properties (such as specific heat capacity, thermal conductivity, and thermal expansion coefficient) of sandstone after high-temperature treatment and the variations of mechanical properties (including peak strength, peak strain, elastic modulus, and whole stress-strain curve) with temperature were analyzed. Indeed, the deterioration law of sandstone after high-temperature treatment was also explored with the aid of a scanning electron microscope (SEM). The results show that with the increase in temperature, the specific heat capacity and thermal expansion coefficient of sandstone samples after high-temperature treatment increase first and then decrease, while the thermal conductivity gradually decreases. The range from room temperature to 1000 °C witnesses the following changes: As temperature rises, the peak strength of sandstone rises initially and falls subsequently; the elastic modulus drops; the peak strain increases at an accelerated rate. Temperature change has a significant effect on the deterioration rules of sandstone, and the increase in temperature contributes to the transition in the failure mode of sandstone from brittle failure to ductile failure. The experimental study on the thermophysical and mechanical properties of sandstone under the action of high temperature and overburden pressure has a guiding significance for the site selection and safety evaluation of UCG projects. [ABSTRACT FROM AUTHOR]

The evolution of fracture zone controls the safety of underground coal gasification (UCG) in terms of gas emission and water leakage. In order to understand the fracture propagation in the confining rock of a UCG cavity with various influence factors, this paper implemented a set of numerical models based on different geological and operating conditions. Analysis was implemented on the mechanism of fracture propagation and its evolution characteristics, suggesting that (a) continuum expansion of the cavity leads a near-field fracture circle in confining rock initially, followed by the roof caving and successive propagation of shear band. (b) The key observed influence factors of fracture propagation are the grade of confining rock, overburden pressure, dimension of the cavity and gasifying pressure, the linear relationships between them, and the fracture height. Additionally, the fracture depth in the base board was mainly caused by tensile fracture. (c) A model was proposed based on the evolution of fracture height and depth in roof and base board, respectively. Validation of this model associated with orthogonal tests suggests a good capacity for predicting fracture distribution. This paper has significance in guiding the design of the gasifying operation and safety assessment of UCG cavities. [ABSTRACT FROM AUTHOR]

This study explored the feasibility of calcium peroxide (CaO 2) to inhibit cyanobacterial blooms of the outbreak and dormancy stages. Our previous studies have found that CaO 2 has a high inhibitory effect on cyanobacteria. In order to explore the application effect of CaO 2 in actual cyanobacteria lake water, we conducted this study to clarify the effect of CaO 2 on inhibiting cyanobacteria in outbreak and dormancy stages. The results showed that CaO 2 inhibited the growth of cyanobacteria in the outbreak and dormancy stages by 98.7% and 97.6%, respectively. The main inhibitory mechanism is: (1) destroy the cell structure and make the cells undergo programmed cell death by stimulating the oxidation balance of cyanobacteria cells; (2) EPS released by cyanobacteria resist stimulation and combine calcium to form colonies, and accelerate cell settlement. In addition to causing direct damage to cyanobacteria, CaO 2 can also improve water quality and sediment microbial diversity, and reduce the release of sediment to phosphorus, so as to further contribute to cyanobacterial inhibition. Finally, the results of qRT-PCR analysis confirmed the promoting effect of CaO 2 on the downregulation of photosynthesis-related genes (rbcL and psaB), microcystn (mcyA and mcyD) and peroxiredoxin (prx), and verified the mechanism of CaO 2 inhibition of cyanobacteria. In conclusion, this study provides new findings for the future suppression of cyanobacterial bloom, by combining water quality, cyanobacterial inhibition mechanisms, and sediment microbial diversity. [Display omitted] • CaO 2 inhibited the growth of cyanobacteria during outbreak and dormancy stages. • CaO 2 inhibited cyanobacteria through oxidative stimulation and colony formation. • 100 mg L−1 CaO 2 enhanced microbial diversity. • Providing the practical application effect of treating cyanobacteria with CaO 2. [ABSTRACT FROM AUTHOR]

The article focuses on a study which examined the use of geocarposphere bacterial strains in reducing groundnut pod colonization by Aspergillus flavus. Visual agar plate assay was used to screen for antifungal and anti-aflatoxin activity. Samples of geocarposphere bacterial isolates were collected from Shandong Province, China. Results of the study showed that the loss of norsolorinic acid accumulation in the fungal mycelium indicate conditions inhibitory to aflatoxin production.

Abstract Environment-friendly algaecides based on allelopathy have been extensively studied to control harmful algal blooms (HABs). The inhibitory effects of linoleic acid (LA) sustained-release microspheres on different cell densities of Microcystis aeruginosa (M. aeruginosa) at different growth phases were studied. The results showed that the growth of M. aeruginosa could be inhibited within 4 days and the constant inhibitory rate with initial algal density of 8 × 105 cells∙mL−1 (exponential phase) was up to 96% compared with control. The chlorophyll-a content in the treatment group had the same change trend with the algal density and declined significantly at day 20th, which suggested that the microspheres could promote the degradation of chlorophyll-a. The activities of superoxide dismutase (SOD) and catalase (CAT) increased gradually within 5 days but then declined sharply, which indicated that LA microspheres could cause oxidative damage to M. aeruginosa during the process of inhibition and reduce the activities of antioxidant enzymes. In addition, the concentration of oxygen free radical (O 2 −) increased at day 10th and rose constantly, and the content of malodialdehyde (MDA) increased to 2.7 times as much as control at day 20th. Furthermore, the content of protein, nucleic acid and the conductivity in culture solution showed a significant rise. These results showed that algal cell membrane lipid peroxidation occurred and the membrane permeability increased, accompanied by the damage of cell membrane. To sum up, the destruction of algal cell membrane is the main mechanism of LA microspheres inhibiting algal growth. [ABSTRACT FROM AUTHOR]

• Plant-biofilm can effectively remove the azithromycin and tetracycline. • More ARGs were generated in mixture antibiotics exposure. • Antagonistic effects on plant were induced by mixture antibiotics exposure. • Antibiotics changed the structural of extracellular polysaccharides in biofilms. • Microbial quorum-sensing on biofilms were change by antibiotics. Antibiotics, such as azithromycin (AZ), tetracycline (TC), and their related antibiotic resistance genes (ARGs), create serious ecological risks to aquatic organisms. This study examined the response mechanisms of submerged macrophytes and periphytic biofilms to a mixture of AZ and TC pollution and determined the antibiotic removal efficiencies and fate of ARGs. The results showed that the plant-biofilm system had a significant capacity for removing both single and combined antibiotics with removal efficiencies of 93.06% ∼99.80% for AZ and 73.35% ∼97.74% for TC. Higher ARG (tetA, tetC, tetW, ermF, ermX, and ermB) abundances were observed in the biofilm, and subsequent exposure to the antibiotic mixture increased the abundances of these genes. Both single and combined antibiotics triggered antioxidant stress, but antagonistic effects were induced only with mixed AZ and TC exposure. Furthermore, the antibiotics changed the structural characteristics of extracellular polysaccharides and induced alterations in the structure of the biofilm microbial community. Increased N-acylated- l -homoserine lactone confirmed alternations in microbial quorum-sensing. The results extend the understanding of the fate of antibiotics and ARGs when aquatic plants and biofilms are exposed to antibiotic mixtures, as well as the organism's response mechanisms. [ABSTRACT FROM AUTHOR]

Abstract: The synthesis of bismuth tungstate (Bi2WO6) multilayered disk which was constructed by oriented square nanoplates was easily realized via a simple surfactant-free hydrothermal method. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM) were used to investigate the as-obtained product. The results indicated that the three-dimensional (3D) Bi2WO6 multilayered disk was constructed by self-assembly of square nanoplates via a perfect oriented manner. The formation mechanism of the product was carefully investigated on the basis of the results of time-dependent experiments. In addition, studies of the photocatalytic property demonstrated that the as-obtained Bi2WO6 could exhibit excellent visible-light-driven photocatalytic activity for the degradation of Rhodamine B (RhB). [Copyright &y& Elsevier]

• FC and CDS reduce the biomass and destroy cells membrane permeability. • FC and CDS changes microbial abundance and diversity on the surface of leaves. • CDS can induce the programmed cell death of plants to accelerate their decline. • The ecotoxicity manifested as CDS > FC. • Stress resistance is Vallisneria natans > Myriophyllum verticillatum. To investigate the deleterious ecological effects of cyanobacteria on submerged macrophytes, this study investigated the effects of different concentrations of fresh cyanobacteria (FC) and cyanobacteria decomposition solution (CDS) on an experimental group of submerged macrophytes (Vallisneria natans (Lour.) Hara and Myriophyllum verticillatum Linn.). The results showed that FC and CDS not only lead to decrease in biomass and significant changes in enzyme activity and chlorophyll content in tissue, but also affected the permeability of cell membranes. The extent of damage was in the order CDS > FC, and the comprehensive stress resistance of Vallisneria natans (2.994) was more than that of Myriophyllum verticillatum (2.895). In addition, semi-permeable membranes can reduce plant damage by FC and CDS, but cannot completely prevent it. FC and CDS mainly affected the relative distribution of microbial genera on the surface of aquatic plants (p < 0.05). Furthermore, CDS caused irreversible damage to plant cells and induced programmed cell death (PCD) of plants to accelerate their decline. Therefore, FC and CDS may be one of the main reasons for the decline in submerged vegetation. This study provides a scientific basis for evaluating the harmful effects of cyanobacteria on submerged macrophytes. [ABSTRACT FROM AUTHOR]