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Piezo‐self‐Fenton system (PESF) has been emerging as a promising water treatment technology but suffering from unsatisfied H2O2 production efficiency. Herein, we rationally design a Bi12O17Cl2 piezo‐catalyst with multiple [Bi−O]n interlayers towards highly efficient H2O2 production. The introduction of [Bi3O4.25] layers initiates dual two‐electron pathway for H2O2 generation by altering the interlayer properties. It is found that the additional [Bi3O4.25] layers not only enhance the polarization electric field but also serve as active sites for triggering dual pathways of two‐electron O2 reduction and H2O oxidation reaction for H2O2 production. Therefore, the Bi12O17Cl2 exhibits an ultrahigh rate of H2O2 generation (7.76 mM h−1 g−1) in pure water. Based on the adequate H2O2 yield, a PESF was constructed for acetaminophen (ACE) degradation with an apparent rate constant of 0.023 min−1. This work not only presents a potential strategy of tuning the activity of bismuth based piezo‐catalysts but also provides a good example on the construction of highly efficient PESF for environmental remediation by using natural mechanical energy. [ABSTRACT FROM AUTHOR]

Piezo‐self‐Fenton system (PESF) has been emerging as a promising water treatment technology but suffering from unsatisfied H2O2 production efficiency. Herein, we rationally design a Bi12O17Cl2 piezo‐catalyst with multiple [Bi−O]n interlayers towards highly efficient H2O2 production. The introduction of [Bi3O4.25] layers initiates dual two‐electron pathway for H2O2 generation by altering the interlayer properties. It is found that the additional [Bi3O4.25] layers not only enhance the polarization electric field but also serve as active sites for triggering dual pathways of two‐electron O2 reduction and H2O oxidation reaction for H2O2 production. Therefore, the Bi12O17Cl2 exhibits an ultrahigh rate of H2O2 generation (7.76 mM h−1 g−1) in pure water. Based on the adequate H2O2 yield, a PESF was constructed for acetaminophen (ACE) degradation with an apparent rate constant of 0.023 min−1. This work not only presents a potential strategy of tuning the activity of bismuth based piezo‐catalysts but also provides a good example on the construction of highly efficient PESF for environmental remediation by using natural mechanical energy. [ABSTRACT FROM AUTHOR]

[Display omitted] • Heterogeneous photo-Fenton system shows high catalytic capability and stability. • Oxygen vacancies accelerate interfacial electron transfer. • Fe(Ⅱ) regeneration is induced by Ce(Ⅳ)/Ce(III) pairs and built-in electric field. • Polycyclic antibiotic has been highly mineralized by sufficient free radicals. Fenton reaction is regarded as a potential treatment for antibiotics removal, but challenges remain due to the sluggish reaction kinetics of Fe(III) reduction and incomplete degradation from insufficient active substance. Distinguished from traditional Fe(Ⅱ) regeneration techniques, this work focuses on utilizing the aliovalent redox pairs and built-in electric field to induce photo-excited electrons to cross the material interface and achieve Fe(III) reduction (heterogeneous regeneration). Herein, oxygen-deficient CeO 2 particles are anchored on metal–organic frameworks (MIL-88A) and thus constitute the heterojunction with enhanced photoelectric properties, accelerating the directional charge transfer. Consequently, the synthesized MIL-88A/CeO 2 (OV) composite can degrade 95.76% of oxytetracycline within 60 min in photo-Fenton reaction and maintain a high mineralization rate (75.33%) after 4 cyclic tests. Furthermore, the charge transfer mechanisms of Fe cycle and antibiotics mineralization are both unveiled via experiment results and theorical calculation. This work proposes a new paradigm for constructing self-sufficient photo-Fenton catalytic system for efficient and sustainable removal of polycyclic antibiotics. [ABSTRACT FROM AUTHOR]

Photocatalytic hydrogen peroxide (H2O2) production from dioxygen and water is regarded as a promising technology since it can achieve sustainable and green solar‐to‐chemical energy conversion. Herein, oxygen and potassium dual‐heteroatom incorporated polymeric carbon nitride (O/KCN) is rationally designed for H2O2 generation with an ultrahigh rate of 309.44 µM h−1 mg−1, which surpasses that of other C3N4‐based photocatalysts. The enhanced performance can be ascribed to the effective light absorption, fast charge transfer/separation, strong oxygen adsorption, and highly selective two‐electron oxygen reduction reaction (ORR). Density functional theory calculations further confirm that the obtained O/KCN is more favorable than others for electrons migrating from β spin‐orbital to π* orbitals of O2 molecule, thus optimizing O2 molecule activation to promote the formation of intermediate species *OOH and decrease the energy barrier of H2O2 production. This work not only provides in‐depth insights for the photocatalytic H2O2 generation mechanism, but also lays the foundation for further development of highly active photocatalysts for environmental remediation and energy conversion. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ecosystem structure and function should both be included in evaluating homeostasis. • A multidimensional framework to reveal homeostasis is proposed. • Cascade hydropower development exhibits cumulative effect on ecosystem homeostasis. • Interaction between nutrients and homeostasis under cascade damming is discussed. • Network analysis and biological source tracing are promising quantitative methods. Cascade hydropower development is an important requirement to promote energy revolution and strengthen clean energy development worldwide. However, ecological conservation has become one among many major factors restricting hydropower development and the problem of green development must be solved crucially, from the perspective of the overall ecosystem. Simultaneously, the lack of a comparative basis has become the bottleneck problem limiting research on the ecological impact of cascade hydropower development. This review synthesizes the variation of river ecosystem homeostasis under hydropower development, highlighting that both the ecosystem structure and function should be considered. According to the definition of ecosystem homeostasis, a multidimensional framework, including temporal stability, resistance, resilience, and recovery perspectives of ecosystems, to completely uncover homeostasis under hydropower development is proposed. Moreover, the cumulative effect of cascade damming on river ecosystem homeostasis is analyzed based on both long- lasting and synergistic spatial effects of cascade reservoirs. The interaction between biogenic substances and ecosystem homeostasis is also discussed and the driving mechanism of homeostasis evolution of river ecosystem is revealed. Furthermore, our study also suggests that network analysis and biological source tracing methods can be applied to quantify the effects of cascade hydropower development on ecosystem homeostasis in future studies. This review is intended to help ecologists, regulators, and others to make informed decisions regarding the rational utilization of hydropower resources, ecological protection, and restoration of hydropower development worldwide. [ABSTRACT FROM AUTHOR]

• Under 500 μg/L SMM-TMP co-exposure, TMP enhanced inhibition of SMM on algal growth. • 500 μg/L SMM-TMP co-exposure reduced photosynthesis and N assimilation in algae. • 5 μg/L of SMM single-exposure and SMM-TMP co-exposure both promoted algal growth. • Algae self-adapt to 5 μg/L exposure, protecting photosynthesis and N assimilation. In aquaculture around the world, sulfamonomethoxine (SMM), a long-acting antibiotic that harms microalgae, is widely employed in combination with trimethoprim (TMP), a synergist. However, their combined toxicity to microalgae under long-term exposures at environmentally relevant concentrations remains poorly understood. Therefore, we studied the effects of SMM single-exposures and co-exposures (SMM:TMP=5:1) at concentrations of 5 μg/L and 500 μg/L on Chlorella pyrenoidosa within one aquacultural drainage cycle (15 days). Photosynthetic activity and N assimilating enzyme activities were employed to evaluate microalgal nutrient assimilation. Oxidative stress and flow cytometry analysis for microalgal proliferation and death jointly revealed mechanisms of inhibition and subsequent self-adaptation. Results showed that exposures at 5 μg/L significantly inhibited microalgal nutrient assimilation and induced oxidative stress on day 7, with a recovery to levels comparable to the control by day 15. This self-adaptation and over 95 % removal of antibiotics jointly contributed to promoting microalgal growth and proliferation while reducing membrane-damaged cells. Under 500 μg/L SMM single-exposure, microalgae self-adapted to interferences on nutrient assimilation, maintaining unaffected growth and proliferation. However, over 60 % of SMM remained, leading to sustained oxidative stress and apoptosis. Remarkably, under 500 μg/L SMM-TMP co-exposure, the synergistic toxicity of SMM and TMP significantly impaired microalgal nutrient assimilation, reducing the degradation efficiency of SMM to about 20 %. Consequently, microalgal growth and proliferation were markedly inhibited, with rates of 9.15 % and 17.7 %, respectively, and a 1.36-fold increase in the proportion of cells with damaged membranes was observed. Sustained and severe oxidative stress was identified as the primary cause of these adverse effects. These findings shed light on the potential impacts of antibiotic mixtures at environmental concentrations on microalgae, facilitating responsible evaluation of the ecological risks of antibiotics in aquaculture ponds. [Display omitted] [ABSTRACT FROM AUTHOR]

The application of antibiotics in freshwater aquaculture leads to increased contamination of aquatic environments. However, limited information is available on the co-metabolic biodegradation of antibiotics by microalgae in aquaculture. Feedstuffs provide multiple organic substrates for microalgae-mediated co-metabolism. Herein, we investigated the co-metabolism of sulfamethoxazole (SMX) by Chlorella pyrenoidosa when adding main components of feedstuff (glucose and lysine). Results showed that lysine had an approximately 1.5-fold stronger enhancement on microalgae-mediated co-metabolism of SMX than glucose, with the highest removal rate (68.77% ± 0.50%) observed in the 9-mM-Lys co-metabolic system. Furthermore, we incorporated reactive sites predicted by density functional theory calculations, 14 co-metabolites identified by mass spectrometry, and the roles of 18 significantly activated enzymes to reveal the catalytic reaction mechanisms underlying the microalgae-mediated co-metabolism of SMX. In lysine- and glucose-treated groups, five similar co-metabolic pathways were proposed, including bond breaking on the nucleophilic sulfur atom, ring cleavage and hydroxylation at multiple free radical reaction sites, together with acylation and glutamyl conjugation on electrophilic nitrogen atoms. Cytochrome P450, serine hydrolase, and peroxidase play crucial roles in catalyzing hydroxylation, bond breaking, and ring cleavage of SMX. These findings provide theoretical support for better utilization of microalgae-driven co-metabolism to reduce sulfonamide antibiotic residues in aquaculture. [Display omitted] • Feedstuff components Glu and Lys enhanced the co-metabolism of SMX by microalgae. • Lys had a stronger enhancement on SMX co-metabolism by microalgae than Glu. • Fourteen TPs from phase-I and phase-II metabolisms were identified by IMS-QTOF-MS. • Glutamyl-conjugation and other four co-metabolic pathways of SMX were proposed. • The top three crucial enzymes for algae to co-metabolize SMX are EROD, FMO, and DHFS. [ABSTRACT FROM AUTHOR]

The expansion of aquaculture produces increasing pollutant loads, necessitating the use of drainage systems to discharge wastewater into surface water. To assess the mass variations and transfer process of aquaculture wastewater, an entire aquaculture drainage investigation lasting for 48 h was conducted, focusing on the nutrients, heavy metals, dissolved organic matter (DOM), and physicochemical properties of drainage in a commercial shrimp farm. The findings revealed that early drainage produced more heavy metals, total nitrogen (TN), dissolved organic nitrogen (DON), and feed-like proteins from aquaculture floating feed and additives, whereas late drainage produced more PO 4 3--P and total dissolved phosphorus (TP). A few pollutants, including DON, Cu, and feed-like proteins, were effectively removed, whereas the contents of TN, dissolved inorganic nitrogen, and Zn increased in the multi-level aquaculture drainage system. Limited dilution indicated that in-stream transfer was the main process shaping pollutant concentrations within the drainage system. In the lower ditches, NO 3 --N, heavy metals, and feed-like proteins exhibited evident in-stream attenuation, while TN and NH 4 +-N underwent significant in-stream enrichment processes, especially in ditch C, with the transfer coefficient values (v f) of –1.74E-5 and –2.04E-5. This indicates that traditional aquaculture drainage systems serve as nitrogen sinks, rather than efficient nutrient purge facilitators. Notably, DOM was identified as a more influential factor in shaping the in-stream transfer process in aquaculture drainage systems, with an interpretation rate 40.79% higher than that of the physiochemical properties. Consequently, it is necessary to eliminate the obstacles posed by DOM to pollutant absorption and net zero emissions in aquaculture drainage systems in the future. Nutrients, heavy metals, and dissolved organic matter are hazardous pollutants originating from high-density aquaculture. As the sole conduit to natural waters, aquaculture drainage systems have pivotal functions in receiving and purifying wastewater, in which the in-stream transfer process is affected by ambient conditions. This field study investigated the spatial variations, stage distinctions, effects of physicochemical properties, and dissolved organic matter (DOM) features. This finding suggests that the aquaculture drainage system as a nitrogen sink and DOM source. While the DOM is the key factor in shaping the in-stream transfer process, and obstacles for pollutant elimination. This study helps in understanding the fate of aquaculture pollutants and reveals the drawbacks of traditional aquaculture drainage systems. [Display omitted] • More heavy metals, TN, DON and feed-like protein exhibited in early drainage. • Aquacultural drainage system were DIN sink rather than good purge facility. • DON and feed-like protein and metals in-stream attenuated in drainage system. • Compared to physicochemical properties, DOM features directly altered the v f. [ABSTRACT FROM AUTHOR]

• Organophosphorus pesticides degradation and in-situ phosphate recovery system was constructed. • The degradation efficiency of trichlorfon in this system surpassed 98% • Phosphorus from the degradation process was recovered in the form of vivianite with the overall recovery rate of 85.1%. • In this system, the toxicity of degradation byproduct was lower than trichlorfon, and iron in the photo-Fenton system is also recovered. • The recovered vivianite has great potential for water treatment. Efficient recovery and utilization of the generated phosphorus during the process of organophosphorus pesticides degradation is promising but still challenging. In this study, a photo-Fenton-crystallization sequential processes were developed to achieve the degradation of organophosphorus pesticides and simultaneous recovery/utilization of the generated phosphate. In this system, iron ions exhibited dual functionality: activator of the photo-Fenton reaction and crystallizing agent of the generated phosphate and the crystals obtained were proved to be vivianite by X-ray Diffraction and Scanning Electron Microscopy. The results showed that a trichlorfon degradation rate exceeding 90% and a vivianite yield of 85.1% was achieved. Parameters such as pH and the Fe-P ratio play pivotal roles in phosphorus recovery efficiency from wastewater. In addition, the toxicity of the degradation by-products was much less than that of trichlorfon by the Toxicity Estimation Software Tool. Additionally, the recovered vivianite exhibits advantageous catalytic properties to activate peroxymonosulfate for the degradation of different pollutants. This study provides a novel perspective for the treatment and utilization of organophosphorus pesticides. [ABSTRACT FROM AUTHOR]

The study investigated the distributions of heavy metals (Cd, Cr, Cu, Mn, and Pb) between dissolved fraction (<0.7 µm) and particles (>0.7 µm) during the adsorption process. The dissolved fraction was further separated into truly dissolved (<3 kDa) and colloidal (3 kDa-0.7 µm) fractions. Significant metal adsorption occurred on the colloids, resulting in their aggregation into particles, which in turn influenced the particle adsorption kinetics. Colloids could either accelerate or inhibit the transformation of metal ions into particulates, depending on their stability. Competitive metals for colloids (Pb and Cr) were more susceptible to the effects of colloids than other elements. DOM was the predominant environmental factor influencing colloid behavior. The XDLVO theory showed that DOM enhanced the negative charge of colloids and made the colloid surface more hydrophilic, inhibiting the aggregation of colloids. DOM resulted in substantial increases in the concentrations of colloidal Pb and Cr from 0.31 μg/L and 4.58 μg/L to 20.52 μg/L and 43.51 μg/L, respectively, whereas the increment for less competitive metals (Cd and Mn) was smaller. These findings suggest that the distribution of heavy metals is influenced not only by adsorption from particles and ions but also by the complex dynamics of colloids. [Display omitted] • Colloids affect metal adsorption capacities and kinetics on particles. • Quick colloid adsorption and aggregation expedite metal ions immobilization. • Colloid behaviors and effects on metals were influenced by environmental factors. • DOM prevented colloid aggregation and increased mobile metal concentrations. • Colloid stability was determined by Lewis acid–base interactions via XDLVO theory. [ABSTRACT FROM AUTHOR]

Iron-based materials are difficult to produce single oxygen (1O 2) efficiently from H 2 O 2. Herein, we demonstrate that 1O 2 production from H 2 O 2 can be manipulated by regulating the lattice distortion degrees of spinel ferrite through controlling the contents of Co and Ni in Co 1−x Ni x Fe 2 O 4. Typically, NiFe 2 O 4 , which owns the lowest lattice distortion degree, can produce 1O 2 as the dominated reactive oxygen species with·O 2 - as the intermediate. Due to the production of 1O 2 , the NiFe 2 O 4 /H 2 O 2 system removes bisphenol A (BPA) completely within 180 min but removes only ∼ 4% of benzoic acid. In addition, the system demonstrates significant resistance to water matrix interference, as 50 mM of Cl-, NO 3 -, H 2 PO 4 -, and humic acid inhibited the BPA degradation by only ∼0%, ∼2%, ∼40%, and ∼3%, respectively. Our work may shed light for regulating the formation of 1O 2 from H 2 O 2 through the rational design of iron-based catalysts for Fenton-like reactions. [Display omitted] • Activating H 2 O 2 to produce 1O 2 by adjusting the lattice distortion of spinel ferrite. • The degree of lattice distortion and the yield of 1O 2 showed a negative correlation. • NiFe 2 O 4 /H 2 O 2 system has selectivity, anti-interference and high H 2 O 2 utilization rate. [ABSTRACT FROM AUTHOR]

1 The photorelease of iron from resuspended sediments were observed along with DOM photorelease. 2 Oxygen and nitrate could promote the photorelease of DOM and iron. 3 Oxidation by hydroxyl radical was the main mechanism of DOM photorelease. Photochemical reactions can alter the transformation of sedimentary organic matter into dissolved organic matter (DOM) and affect its ultimate fate in water ecosystems. In the present study, the photorelease of DOM and Fe from resuspended lake sediments was investigated under different O 2 and NO 3 − concentration conditions to study the mechanisms of DOM and Fe photorelease. The amount of photoreleased Fe, which ranged from 0.22 to 0.70 μmol/L, was significantly linearly correlated with the amount of photoreleased DOM. O 2 and NO 3 − could promote the photochemical release of DOM and Fe, especially during the initial 4 h irradiation. In general, the order of the photorelease rates of DOM and Fe under different conditions was as follows: NO 3 −/aerobic > aerobic ≈ NO 3 −/anaerobic > anaerobic. The photorelease rates of DOM and Fe were higher for the initial 4 hr irradiation than these for the subsequent 8 hr irradiation. The photorelease of DOM and Fe is thought to proceed via direct photodissolution and indirect processes. The relative contributions of indirect processes (>60%) was much greater than that of direct photodissolution (<40%). The photoproduced H 2 O 2 under aerobic and anaerobic conditions indicated that hydroxyl radicals (•OH) are involved in the photorelease of DOM. Using •OH scavengers, it was found that 38.7%, 53.7%, and 77.6% of photoreleased DOM was attributed to •OH under anaerobic, aerobic, and NO 3 −/aerobic conditions, respectively. Our findings provide insights for understanding the mechanisms and the important role of •OH in the DOM and Fe photorelease from resuspended sediments. [Display omitted] [ABSTRACT FROM AUTHOR]

Agricultural drainage ditches (ADDs) are ubiquitous and regarded as active zones for biogeochemical reactions and microbe-mediated pollutant removal. However, little is known about the microbial distribution and community assembly in ADDs. Here, a typical large-scale irrigation district, including five orders of farmland drainage systems (namely field, sublateral, head, branch, and trunk ditches that could efficiently remove excess water from paddy fields to downstream water bodies), was selected to investigate the ecological processes of microbial communities and N- and P-transformation processes in multistage ditches. We found that scale effects drove distinct environmental gradients and microbial community dissimilarities and that the five ordered ditches were grouped into three clusters (field vs. sublateral vs. head, branch, and trunk ditches). Specifically, the microbial communities in the field ditches located adjacent to the paddy fields were strongly selected by agricultural fertilization and irrigation drainage, enriching salt-tolerant microbes with high nitrification and inorganic P solubilization capabilities. In comparison, the sublateral ditches showed the highest removal performance for total nitrogen (13.28–55.80%) and total phosphorus (9.06–65.07%) during the growth of rice, which was mainly attributed to the enrichment of versatile microbiota (e.g., C39 , Nitrospira, and Novosphingobium) as a result of the increased stochastic processes driven by the low redox potential. Notably, the specific gene (i.e., hzsB) for anaerobic ammonium oxidation in sublateral ditches was 1–2 orders of magnitude higher than in adjacent ditches, further contributing to N loss. As field water was discharged into the large-sized head, branch, and trunk ditches, the nutrient levels decreased sharply. At the same time, deterministic processes gained more importance (∼82%), leading to the flourishing of Synechococcus and increasing the potential risk of eutrophication. Overall, the microbial communities in multistage ADDs were co-shaped by agricultural practices and ditch size, which further governed the N and P removal performance. These results provide unique insights into microbiota assembly patterns and dynamics in multistage ADDs and important ecological knowledge for controlling agricultural non-point source pollutants by managing of small-sized ditches. [Display omitted] • Microbial dynamics and their contributions to N and P removal were investigated. • Microbial communities in multistage drainage ditches were scale dependent. • Agricultural practices and ditch size co-shape the microbial communities in ditches. • Local heterogeneity enhanced stochastic process and enriched functional microbiota. • Multistage drainage ditches were efficient to control non-point source pollutants. [ABSTRACT FROM AUTHOR]

A novel photocatalytic system was developed for the simultaneous degradation of organic contaminant and generation of H 2 O 2 based on molecular-engineered carbon nitride (AQ-CN x). The AQ-CN x was synthesized by simultaneously introducing N defects and anthraquinone-2-carboxylic acid. Synergistically, the AQ-CN x exhibited a H 2 O 2 production rate of 36.41 mM h−1 g−1, which is 7.87 times as that of CN. More importantly, atenolol (ATL) can promote H 2 O 2 production, which in turn increases ATL degradation. Density functional theory (DFT) calculations demonstrate that N defects provide more sites for O 2 adsorption and AQ acts as an electron-acceptor to facilitate the separation of photogenerated electrons and holes. Independent gradient model based on Hirshfeld partition (IGMH) analysis shows that van der Waals interaction between AQ-CN x and ATL enhances the degradation efficiency. This work provides a new idea for the effective degradation of pollutants and simultaneous generation of H 2 O 2. [Display omitted] • Molecular level engineered carbon nitride was synthesized by simultaneously introducing N defects and AQ-COOH. • The photocatalyst promotes the simultaneous degradation of ATL and generation of H 2 O 2. • The photocatalyst improves the adsorption of O 2 and produces more ROS in situ by activating O 2 molecule. • DFT calculations further demonstrate N defects and AQ-COOH promote efficient separation of charges. [ABSTRACT FROM AUTHOR]

• Advances in emerging interfacial water evaporation towards water purification. • The main design principles of advanced photothermal materials are summarized. • Reported strategies to overcome technology issues and enhance evaporation rate. • Key technology issues and challenges in photothermal water treatment. Solar-driven interfacial water evaporation has received considerable attention as a potential solution for wastewater treatment applications. Despite previous studies confirming significant performance improvements through rational solar evaporator design, challenges remain in achieving comprehensive condensed water purification and addressing high pollutant concentrations in source water. In this review, we evaluate the optimization strategies for solar absorption, thermal management, and water-existing forms to achieve high-efficiency water evaporation. In addition, we provide a brief overview of photothermal materials that are based on a variety of different photothermal conversion mechanisms. Based on previous research, our focus is on exploring purification strategies using interfacial water evaporation technology to address common water pollutants, including volatile organic compounds, dyes, metal ions, and more. Lastly, we discuss the challenges of practical implementation of interfacial water evaporation technology in the field of wastewater treatment, followed by our views and future perspectives. [ABSTRACT FROM AUTHOR]

Summary: Despite the essential functions of sedimentary bacterial and fungal communities in biogeochemical cycling, little is known about their biogeographic patterns and driving processes in large rivers. Here we investigated the biogeographic assemblies and co‐occurrence patterns of sedimentary bacterial and fungal communities in the Jinsha River, one of the largest rivers in southwestern China. The mainstream of river was divided into upstream, midstream and downstream. The results showed that both bacterial and fungal communities differed significantly among three sections. For both communities, their composition variations in all sites or each river section were controlled by the combination of dispersal limitation and environmental selection, and dispersal limitation was the dominant factor. Compared with bacteria, fungi had stronger dispersal limitation. Co‐occurrence network analyses revealed higher network connectivity but a lower proportion of positive interaction in the bacterial than fungal network at all sites. In particular, the keystone species belonging to bacterial phyla Proteobacteria and Firmicutes and fungal phyla Ascomycota and Chytridiomycota may play critical roles in maintaining community function. Together, these observations indicate that fungi have a stronger dispersal limitation influence and less network connectivity than bacteria, implying different community assembly mechanisms and ecological functions between bacteria and fungi in large rivers. [ABSTRACT FROM AUTHOR]

Rising atmospheric carbon dioxide (CO 2) may stimulate the proliferation of cyanobacteria. To investigate the possible physiological responses of cyanobacteria to elevated CO 2 at different nutrient levels, Microcystis aeruginosa were exposed to different concentrations of CO 2 (400, 1100, and 2200 ppm) under two nutrient regimes (i.e., in nutrient-rich and nutrient-poor media). The results indicated that M. aeruginosa differed in its responses to elevated atmospheric CO 2 at different nutrient levels. The light utilization efficiency and photoprotection of photosystem II were improved by elevated CO 2 , particularly when cells were supplied with abundant nutrients. In nutrient-poor media, both total organic carbon and the polysaccharide/protein ratio of the extracellular polymeric substance increased with elevated CO 2 , accompanied by high cellular carbon/nitrogen ratios. Besides, cells growing with fewer nutrients were more prone to suffer intracellular acidification with elevated CO 2 than those growing with abundant nutrients. Nonetheless, alkaline phosphate activity of cyanobacteria was improved by high CO 2 , provided that reduced pH was in the optimum range for alkaline phosphate activity. Nitrate reductase activity was inhibited by elevated CO 2 regardless of nutrient levels, leading to a reduced nitrate uptake. These changes indicate that the biogeochemical cycling of nutrients would be affected by higher atmospheric CO 2 conditions. Overall, cyanobacteria in eutrophic waters may benefit more than in oligotrophic waters from rising atmospheric CO 2 concentrations, and evaluations of the influence of rising atmospheric CO 2 on algae should account for the nutrient level of the ecosystem. Unlabelled Image • Elevated CO 2 improved photosystem II particularly under nutrient-rich conditions. • Effects of elevated CO 2 on the EPS of M. aeruginosa were related to nutrient level. • Intracellular acidification may be facilitated in high-CO 2 , nutrient-poor waters. • The AP activity of M. aeruginosa improved with higher CO 2 at low nutrient levels. • Elevated CO 2 inhibited NR activity in M. aeruginosa regardless of nutrient levels. [ABSTRACT FROM AUTHOR]

• DOP is highly bioavailable in Lake Taihu, China, especially in Meiliang Bay. • DOP utilization is vital in shaping phytoplankton community in P-deficient waters. • High APA expression is not equal to the high capacities of DOP utilization. • Low algal APA implies the restriction of other factors under P-deficient conditions. • APA can be used to optimize the prediction of algal blooms in P-deficient lakes. Dissolved organic phosphorus (DOP) could be transformed to dissolved inorganic phosphorus (DIP) under phosphorus (P) deficient conditions by various enzymes, among which alkaline phosphatase activity (APA) is regarded as the most important one. To better understand the different response of phytoplankton to DOP and the role of alkaline phosphatase activity (APA) in phytoplankton growth in natural waters, the distribution of P, APA, and phytoplankton density were measured at 12 sites in Lake Taihu, China, in summer, autumn, and winter of 2016. In this study, 34.12% of DOP could be hydrolyzed, indicative of the high bioavailability of DOP in Lake Taihu, especially in Meiliang Bay. More than 70% of enzymatically hydrolyzed DOP came from alkaline phosphatase-hydrolyzed DOP, verifying that APA had a major role in hydrolyzing DOP to fulfill the DIP requirements of phytoplankton, and that phosphomonoesters were the main form of bioavailable DOP in Lake Taihu. Redundancy analysis implied a high capacity of DOP use may be important for species dominance under P-deficient conditions, but high APA expression is not equal to the high capacities of DOP utilization. In this study, phytoplankton density was significantly positive with bulk APA, algal APA and bacteria APA. APA, despite of its complex contributors, is able to increase the amount of bioavailable P for phytoplankton growth. Moreover, algal APA reflects the actual response of phytoplankton to available P under P-deficient conditions. Low algal APA means that other factors limit phytoplankton growth. Increased algal APA means that other limitations get alleviated and algae are in anxious demand for P. Therefore, this paper suggests that monitoring APA can be used as a supplementary indicator to reflect the actual demand for P of algal, thus to optimize the prediction of algal blooms. [ABSTRACT FROM AUTHOR]

Solar-driven interfacial water evaporation is an effective way to produce clean freshwater. However, it is still challenging that volatile organic compounds might enter the condensate in the evaporation process. Herein, we designed a novel bifunctional photothermal membrane (Co-N-C/CF) that can be applied for simultaneous water evaporation and persulfate mediating water purification. Due to the molecular thermal vibrations effect of carbon-based materials, plasmonic effect of Co NPs, the membrane exhibited an impressive water evaporation rate of 1.88 kg m−2 h−1 (1 sun irradiation). Furthermore, Co-N-C/CF could effectively activate persulfate for phenol (PE) removal through a non-radical reaction process. Experiments and density functional theory calculations illustrated that PE is favorable to be degraded while water molecules are easier to be converted into vapor in the photothermal evaporation process. Hence, the combination of persulfate-based oxidation and solar-driven water evaporation shows great application potential in the durable and efficient production of clean water. [Display omitted] • A novel bifunctional photothermal membrane (Co-N-C/CF) was successfully fabricated. • Co-N-C/CF was applied for water evaporation and PS mediating water purification. • Vertically aligned nanosheets array enhanced the absorption of sunlight. • Co NPs could provide electrons to the outer carbon layer of the Co-N-C/CF. • The weak interactions were graphically revealed by interaction region indicator. [ABSTRACT FROM AUTHOR]

Abstract Dam construction significantly influences riparian ecological functions and environmental conditions in the reservoir region. Despite the importance of diazotrophic mediation of nitrogen cycling in riparian ecosystems, knowledge concerning the impacts of dam construction on diazotrophic function and community composition remains very limited. Here, riparian soils were collected from control sites and dam-affected sites located in six cascade dam-formed reservoirs on the Lancang River, China. Diazotrophic activity was assessed by measuring nitrogen fixation rate, while bacterial abundance and community composition were determined with the nifH gene, using quantitative real-time polymerase chain reaction and MiSeq sequencing, respectively. The results indicate that the activity, abundance, and ɑ-diversity of diazotrophs in the affected sites were significantly higher than those in the control sites. The diazotrophic community composition was differed between the control and affected sites, with the latter showing significantly lower community dissimilarity than the control. Both geographic distance and environmental heterogeneity varied in the diazotrophic community, while environmental heterogeneity was the primary factor controlling diazotrophic assemblage in riparian soils, especially at the affected sites. Moreover, co-occurrence network analyses revealed a much higher possible network connectivity at the affected sites than at the control sites. This study suggests distinct activity, abundance, distribution pattern, and network structure of the diazotrophic populations in riparian soils between dam-affected and control sites; thus, providing a novel insight into the potential ecological effects of dam construction on nitrogen cycling. Graphical abstract Image 1 Highlights • Dam-affected sites had higher nitrogen fixation rates than control sites. • The abundance and ɑ-diversity of diazotrophs were increased in dam-affected sites. • The affected sites had significantly lower community dissimilarity than the control sites. • Environmental heterogeneity was a primary factor affecting diazotrophic assemblage. • Diazotrophic networks were more complex in dam-affected sites than the control sites. [ABSTRACT FROM AUTHOR]

Highlights • CdS-MoS 2 -MXene composites were prepared via a simple hydrothermal method for the first time. • The composites exhibited greatly enhanced photocatalytic hydrogen evolution rate. • The synergetic effect of MoS 2 and Mxene contributed to the high activity. Abstract Water splitting under visible light irradiation over earth-abundant, inexpensive and high active catalysts is an effective and direct way to obtain renewable H 2 energy. Here, a kind of novel noble-metal-free composite photocatalyst with high hydrogen evolution performance was synthesized by a simple hydrothermal method. In the composite, MXene slice with excellent conductivity was used to promote the activity of CdS-MoS 2 catalyst. A prominent H 2 generation rate of 9679 μmol⋅g−1⋅h−1 for the ternary composite was obtained under the irradiation of visible light (λ ≥ 420 nm). It exhibited a great enhancement by a factor of 251.3% in comparison with CdS-MoS 2. The exceptional performance of CdS-MoS 2 -MXene was mainly arised from the high carrier mobility of MXene, which facilitates the separation of photoinduced electron-hole pairs. The present findings would provide a new direction towards exploring MXene-based composite photocatalysts with high photocatalytic performance in water splitting. [ABSTRACT FROM AUTHOR]

Abstract Different environmental dynamics of sediment organic matter (SOM) and suspended particulate organic matter (SPOM) result in great disparities in characteristics and subsequent interactions with heavy metals. In this study, sediments and suspended particles were collected from two large and shallow lakes (Taihu and Hongze Lake) to study the difference in the characteristics and copper binding properties between SOM and SPOM through spectroscopy method. Our results showed that SPOM in Taihu Lake was dominated by autochthonous tyrosine-like substance and SOM was dominated by terrestrial humic-like substance, whereas SPOM in Hongze Lake was dominated by terrestrial humic-like substances. Furthermore, dissolved organic matter (DOM) in Taihu and Hongze Lake was controlled by autochthonous protein and terrestrial humic substances, respectively. Comparison of SPOM between these two lakes indicated that various organic matter sources could be responsible for the organic matter characteristics in suspended particles. Meanwhile, relatively higher binding affinities and more binding sites were observed for SPOM in both two lakes compared to SOM through two-dimensional correlation spectroscopy (2D-COS) analysis of synchronous fluorescence spectra. Moreover, 2D-COS analysis of FTIR spectra revealed that hydrophobic groups (i.e., phenolic groups) had higher binding affinity than hydrophilic groups (i.e., polysaccharide groups) for both SOM and SPOM. Our results provide a new angle for understanding the suspended particles in shallow lakes, which might play a more important role in the environmental behaviors of heavy metals, than has been previously thought. Graphical abstract Image 1 Highlights • Organic matter characteristics in sediments and suspended particles were studied. • SPOM and SOM had significantly different characteristics and sources. • More binding sites and higher binding affinities for SPOM with Cu(II). • Phenolic groups play important role in Cu binding with both SOM and SPOM. [ABSTRACT FROM AUTHOR]

Abstract In this work, the visible light responsive photoelectrocatalytic performance of titanium dioxide nanorod arrays (TiO 2 -NRs) were improved by the synergetic effect of heterojunction construction and doping strategy. First of all, the conductivity of TiO 2 -NRs was improved by niobium doping. The photocurrent of doped sample was 1.39 times larger than that of the pristine TiO 2 -NRs under UV light. On this basis, g-C 3 N 4 was coated onto the niobium doped TiO 2 -NRs and induced to significant enhanced photoelectrochemical performance under visible light irradiation. The optimal Nb-TiO 2 /g-C 3 N 4 photoanode generated a photocurrent of 9.33 mA, which was about 19.04 times as that of the Nb-TiO 2 nanorod. Graphical abstract Unlabelled Image Highlights • Novel Nb-TiO 2 /g-C 3 N 4 photocatalysts were synthesized by a facile method using hydrothermal and saturated aqueous solution. • The Nb-TiO 2 /g-C 3 N 4 photocatalysts have enhanced photoelectrocatalytic activity under visible light irradiation. • The photoelectric catalysis performance of TiO 2 - NRs was improved by the heterojunction and the doping strategy. [ABSTRACT FROM AUTHOR]

Abstract In this study, we investigated the effects of copper oxide (CuO) NPs on freshwater sediment biofilms in terms of the functional properties and microbial community structure. Biofilms were incubated in microcosms and CuO NPs (1 mg/L uncoated and humic-acid-coated) were exposed with Cu2+ (Cu(NO 3) 2) as the positive control. As determined from DO (dissolved oxygen) microelectrodes measurements, a high-DO region emerged inside the biofilms after 5-day exposure to CuO NPs compared with those before NP additions, which suggested CuO NPs inhibit the oxygen respiration activity. These results were consistent with the decreased heterotrophic respiration. CuO NPs significantly altered the bacterial community composition and decreased the abundances of Anaerolineaceae , Acidobacteria , Aminicenantes , and Anaerolinea. Functional analysis from PICRUSt (Phylogenetic Investigation of Communities by Reconstruction of Unobserved States)-predicted metagenomes indicated that bacterial genera depleted by CuO NP treatments were related to carbohydrate and glycan biosynthesis and metabolism, and biosynthesis of other secondary metabolites. These functional profiles combined with the decreased activities of extracellular enzymes, β-glucosidase (GLU) and l -leucine aminopeptidase (LAP), suggested that the introduction of CuO NPs exhibit negative effects on the biogeochemical processes and the cycling of carbon and nitrogen in biofilm systems. Whereas these toxic effects of CuO NPs could be mitigated when the aquatic environment is enriched with natural organic matters such as humic acid. Graphical abstract Unlabelled Image Highlights • Studied effects of CuO NPs on microbial community and functions of sediment biofilms • A high-DO region was observed inside the biofilm using DO microelectrodes. • CuO NPs altered the bacterial community composition and reduced the diversity. • PICRUSt-predicted metagenomes showed carbohydrate metabolism pathways were depleted. • Enriched HA mitigated the toxic effects of CuO NPs on biofilms. [ABSTRACT FROM AUTHOR]

Abstract Microplastics are frequently detected in freshwater environments, serving as a new factitious substrate for colonization of biofilm-forming microorganisms. Distinct microbial assemblages between microplastics and surrounding waters have been well documented; however, there is insufficient knowledge regarding biofilm colonization of plastic and non-plastic substrates, despite the fact that microbial communities generally aggregate on natural solid surfaces. In this study, the effects of substrate type on microbial communities were evaluated by incubation of biofilms on microplastic substrates (polyethylene and polypropylene) and natural substrates (cobblestone and wood) for 21 days under controlled conditions. Results from high-throughput sequencing of 16S rRNA revealed that the alpha diversity (richness, evenness, and diversity) was lower in the microplastic-associated communities than in those on the natural substrates, indicating substrate-type-coupled species sorting. Distinct community structure and biofilm composition were observed between these two substrate types. Significantly higher abundances of Pirellulaceae , Phycisphaerales , Cyclobacteriaceae , and Roseococcus were observed on the microplastic substrates compared with the natural substrates. Simultaneously, the functional profiles (KEGG) predicted by Tax4Fun showed that the pathways of amino acid metabolism and metabolism of cofactors and vitamins were increased in biofilms on the microplastic substrates. The findings illustrate that microplastic acts as a distinct microbial habitat (compared with natural substrates) that could not only change the community structure but also affect microbial functions, potentially impacting the ecological functions of microbial communities in aquatic ecosystems. Graphical abstract Unlabelled Image Highlights • Alpha diversity of biofilms was lower on microplastic than on natural substrates. • Community structure and composition varied between biofilms on different substrates. • Metabolic pathways were altered in biofilms colonizing microplastic. • Microplastic is a new microbial niche affecting microbial structure and function. • This alteration in biofilms may have an ecological impact on aquatic ecosystems. [ABSTRACT FROM AUTHOR]

Abstract Photocatalytic water splitting has aroused great interest as a clean and renewable energy conversion process. In this study, we prepared a novel noble-metal-free multiple heterojunction photocatalyst (CdS@C-CoP) composed of CdS nanorods, conducting carbon layer and CoP nanoparticles cocatalyst for the first time. The obtained CdS@C-CoP composites exhibited excellent performance and stability under visible light irradiation when it was used as photocatalysts for hydrogen evolution. For the optimum CdS@C-CoP sample, an average hydrogen evolution rate reached up to 10089 μmol g−1 h−1, nearly 6 fold as high as that of pure CdS. The enhanced photocatalytic hydrogen production rate can be ascribed to the synergistic effect between conductive carbon layer and surface cocatalyst CoP, which resulted in efficient separation of photoexcited charge carriers and abundant active sites for hydrogen reduction. This work presented a novel way to design composite photocatalyst with efficient hydrogen generation properties through combining two kinds of surface modification methods: thin carbon layer coating and surface cocatalysts loading. Highlights • Well-designed CdS@C-CoP composite is designed for the first time. • Greatly enhanced photocatalytic hydrogen evolution rate and stability under visible light irradiation. • Synergism between carbon layer and CoP is beneficial for the CdS nanorods to achieve high hydrogen evolution performance. [ABSTRACT FROM AUTHOR]

Highlights • Oxygen vacancy and P codoped TiO 2 -Carbon nanotube composites was prepared. • Samples exhibited high efficiency for acetaminophen degradation under visible light. • P doping and oxygen vacancy promote photo-generated carriers separation and transfer. Abstract In the past two decades, carbon-titania composite photocatalysts had attracted extensive attention for high photocatalytic performance. However, their visible light driven activity was still limited. Therefore, it was urgent to find a way to improve its visible light responsive photocatalytic activity. In the present work, a novel efficient visible light driven photocatalysts, oxygen vacancies and phosphorus (P) codoped titania coated carbon nanotube composites (OVPTCN), were prepared by a facile two step solvothermal and phosphorization method for the first time. The obtained sample exhibited significantly enhanced photocatalytic performance for acetaminophen (ACE) degradation under visible light irradiation. The effects of carbon nanotube (CNT) amount and phosphorization content on the photocatalytic efficiency for ACE degradation were also investigated deeply. Results showed that the optimal sample exhibited a high rate constant of 0.025 min-1 for ACE degradation in contrast to that of pure TiO 2 (0.00053 min-1) and titania-carbon nanotube (TCN) composite (0.0036 min-1). The characterization results suggested that phosphorization could produce oxygen vacancies and P dopants in TiO 2 , thus narrowing the band gap of TiO 2 , increasing the transfer and separation efficiency of photogenerated charges. Moreover, it was revealed by EIS Nyquist plots that CNT got better conductivity after the solvothermal reaction and phosphorization, which also increased the transfer efficiency of charges. Therefore, the synergistic effect of P doping, oxygen vacancies and better conductivity of CNT resulted in the significantly enhanced visible light responsive photocatalytic performance. The transformation products and degradation pathway were analyzed based on the results of liquid chromatography-mass spectrometry (LC/MS). Our work provided a new way to prepare efficient visible light driven composite photocatalysts for drugs removal. [ABSTRACT FROM AUTHOR]

Abstract Cerium oxide nanoparticles (CeO 2 NPs) affected the production of extracellular polymeric substances (EPSs), and thus might bring challenges for sludge pumping and mixing. In the present study, we investigated the rheological behavior of sludge before and after extraction of different EPSs fractions under various CeO 2 NPs concentrations. It was found that the removal of loosely bound EPSs (LB-EPSs) could affect the shear stress (τ) and apparent viscosity (η), and the changes were dependent on CeO 2 NPs concentrations. The removal of tightly bound EPSs (TB-EPSs) either with or without the addition of CeO 2 NPs significantly decreased the yield stress (τ y) and the limiting viscosity (η ∞). Furthermore, the dynamic (strain, frequency and time) sweep measurements proved that the storage modulus (G') decreased after the extraction of TB-EPSs, indicating the weakened elastic and solid-like properties. The fluctuated content of polysaccharide in LB-EPSs and the increased amount of protein in TB-EPSs were likely to contribute to the variation of viscoelastic behaviors after the removal of LB-EPSs and TB-EPSs, respectively. In addition, the decreased rheological properties of sludge was also related to the increased zeta potential, decreased particle size and the removal of key organic matters of (104–106 Da) with the extraction of stratified EPSs. These results were significant to take advantages of the rheological properties for sludge treatment in the presence of NPs. Graphical abstract fx1 Highlights • Steady shear flow and dynamic sweep tests were conducted for sludge rheology. • Less than 5 mg/L CeO 2 NPs increased sludge flowability, being opposite to 20 mg/L. • The removal of EPSs weakened elastic and solid-like properties of sludge. • The removal of EPSs increased repulsive forces and reduced hydrophobic interaction. [ABSTRACT FROM AUTHOR]

The photocatalytic technology based on solar energy is a potential approach to mitigate environmental problem. The surface property of photocatalysts and the separation efficiency of photo-generated spatial charge are considerably important to enhance their photocatalytic activity in the decomposition of organic pollutants in wastewater. In this work, phosphate group grafted twinned BiPO 4 with surface phase junction were controllably synthesized by a facile two-step method. XRD results showed that two crystal phases of nMBIP and mMBIP were formed in the twinned BiPO 4 . The formation of phase junction in BiPO 4 was also validated by HRTEM. XPS spectra confirmed that PO 4 3− successfully grafted on the surface of the twinned BiPO 4 . The apparent rate constants of the twinned BiPO 4 for degradation of methylene blue (MB) and carbamazepine (CBZ) improved 5.3 and 5.0 times respectively compared to pristine BiPO 4 because of the formed phase junction. After phosphate grafting on the surface of phase junction, the apparent rate constants for MB and CBZ degradation were further boosted, which were 3.0 and 5.2 times as high as that of twinned BiPO 4. The photocatalytic intermediates of CBZ were detected by HPLC-ESI-MS/MS, and a deductive degradation pathway of CBZ was proposed. Transient photocurrent responses, PL and Mott-Schottky analysis verified that the enhanced photocatalytic activity of phosphate group grafted twinned BiPO 4 with phase junction for the degradation of MB and CBZ was ascribed to faster transfer, efficient separation and improved redox ability of photo-induced charge carriers. [ABSTRACT FROM AUTHOR]

Photocatalytic water splitting is considered to be a promising strategy for addressing the global energy crisis through the expanded use of solar energy. Herein, cadmium sulfide (CdS) nanorods modified with a thin conductive carbon layer and a nickel phosphide co-catalyst, referred to as cadmium sulfide coated with a carbon layer and nickel phosphide (CdS@C/Ni 2 P, where @ indicates a core–shell structure), were synthesized and applied as a novel composite photocatalyst for water splitting. The optimized CdS@C/Ni 2 P composite showed a high photocatalytic hydrogen generation rate of 32030 μmol h −1  g −1 , which was approximately 19 times as high as that of pure CdS. We believed that the thin carbon layer acted as an electron acceptor to promote charge transfer and protect the CdS nanorods from photocorrosion. In addition, the surface loading of the nickel phosphide (Ni 2 P) cocatalyst was able to further draw photogenerated electrons from the cadmium sulfide coated with a carbon layer (CdS@C) heterojunction and provide active sites for hydrogen evolution. Thus, greatly enhanced hydrogen generation was achieved through a combination of carbon coating and surface cocatalyst loading. This development provides a new way to design composite photocatalysts with multiple junctions for efficient water splitting performance. [ABSTRACT FROM AUTHOR]

Development of photocatalysts with characters of low-cost, environment friendliness, visible light response and good performance is vital for the transformation of solar energy into hydrogen fuel. Here, we constructed CoP CdS nanorods hybrid composites via a novel two-step in-situ growth method for the first time. The obtained CoP CdS composites exhibited remarkably enhanced photocatalytic performance and excellent stability in comparison with bare CdS nanorods. Notably, the optimum H 2 evolution rate of 1 wt% CoP CdS was 9.11 times higher than that of pristine CdS. The apparent quantum efficiency of the photocatalyst was calculated to be 11.6%. The superior activity of this material could be attributed to the role of well dispersed CoP nanoparticles and the intimate interface between CoP cocatalysts and CdS nanorods, which efficiently accelerated the separation and transfer of photogenerated electrons. This work provided a new in-situ growth method for the preparation of transition metal phosphides coated photocatalysts with boosted photocatalytic activity of hydrogen evolution. [ABSTRACT FROM AUTHOR]

Electrocatalytic nitrate reduction into recyclable ammonia (NH 3) plays a critical role in maintaining the global nitrogen balance and meeting the growing energy demand. However, the research on controllable defects of traditional semiconductor electrocatalytic materials remains lacking, resulting in limiting nitrate reduction reaction (NO 3 RR) activity. Herein, we develop a facile electrical joule heating method to flexibly regulate the sulfur vacancies (SVs) content on the surface of Ni 3 Co 6 S 8 (NCS), in which SVs can regulate the electronic structure of NCS. Therefore, more 3 d electrons can be localized at Co sites that can reduce the energy barrier of the rate-determining step (HNO 3 *→NO 2 *). As a result, the NCS with reasonable SVs concentration exhibits the outstanding selectivity (98.2%), Faradaic efficiency (85.3%) and yield rate (2388.4 μg h−1 cm−2) for electrocatalytic nitrate reduction to ammonia while maintaining their structural integrity. This work provides a new insight for addressing both nitrate pollution and ammonia energy production. [Display omitted] • Optimization of sulfur vacancies (SVs) on Ni 3 Co 6 S 8 (NCS) surface by electric joule heating method. • Sulfur vacancies can tune electronic structure and enhance the electrochemical activity of NCS. • A highly ammonia yield rate (2388.4 μg h−1 cm−2) and selectivity (98.2%) are obtained on the NCS with appropriate SVs. • The facilitated formation of NO 2 * by SVs is essential for improving the conversion of NO 3 - to NH 3. [ABSTRACT FROM AUTHOR]

Piezo‐catalysis, which is possible to utilize natural mechanical energy, is an ideal technology for synthesizing hydrogen peroxide (H2O2) but is still challenging. Herein, C‐layer coated ZnO (C‐ZnO) with modulated electronic structure is constructed for piezo‐catalytic H2O2 generation. The C‐layer not only provides more active sites but also induces higher piezo‐response to mechanical stimuli. As a result, the optimized C‐ZnO exhibits ultrahigh piezocatalytic activity for H2O2 yield with a rate of 294 µM h−1 in pure water. Theoretical calculation demonstrates that the interaction at the interface induces charge redistribution, leading to the hole accumulation on the surface, thus promoting one‐electron water oxidation. In addition, the C‐ZnO exhibits excellent piezo‐catalytic performance for the degradation of different pollutants. This study not only provides a promising way (utilization of mechanical energy) for efficient H2O2 production in pure water but also opens a new avenue for designing highly active piezo‐catalytic systems for pollutants degradation. [ABSTRACT FROM AUTHOR]

Atrazine, a typical herbicide, has caused extensive concern due to its wide application and persistance. In this work, a visible light responsive photocatalyst BiOBr/UiO-66 was synthesized and applied to the degradation of atrazine. The BiOBr/UiO-66 materials exhibited significantly enhanced photocatalytic performance on the degradation of atrazine under visible light irradiation compared to pure BiOBr. Moreover, the effects of typical environment factors (i.e. pH, common anions, inorganic cations and water matrix) on the degradation of atrazine were investigated extensively. Results showed that atrazine was degraded with the fastest rate at the strong acidity conditions of pH = 3.1 in the investigated pH region (3.1–9.4). The photocatalytic degradation of atrazine was obviously inhibited by HCO 3 − and SO 4 2− . However, Cl − had negligible influence on the degradation of atrazine. Inorganic cations had little influence on the degradation of atrazine. Futhermore, the water matrix showed apparent impacts on the photocatalytic degradation of atrazine by BiOBr/UiO-66. In mineral water, tap water and river water, the removal efficiency of atrazine was evidently lower than that in pure water. The main active species that responsible for the degradation of atrazine by BiOBr/UiO-66 were determined to be ·O 2 − and h + . Ultimately, the degradation pathways of atrazine were proposed based on the intermediates detected by LC-MS/MS. [ABSTRACT FROM AUTHOR]

In the present work, we reported a simple method for the simultaneous phosphorus (P) doping and oxygen vacancies creation on TiO 2 in a single step. The obtained P-doped TiO 2 with surface oxygen vacancies (PTSOV) samples exhibited efficient photocatalytic activity for the degradation of fluoroquinolone antibacterial agent (ciprofloxacin) under visible light irradiation. The optimized sample showed a rate constant of 0.065 min −1 for degradation of ciprofloxacin (CIP) and it was about 16.2 times as high as that of TiO 2 (0.004 min −1 ). The transformation products of CIP were identified by liquid chromatography–mass spectrometry (LC–MS), and degradation pathway was tentatively proposed. The doping state of P and the formation of surface oxygen vacancies (SOVs) were investigated by different methods. X-ray diffraction (XRD) and X-ray Photoemission Spectroscopy (XPS) revealed P 5+ doped via formation Ti O P bond. Electron paramagnetic resonance (EPR) spectroscopy revealed that SOVs were generated on P-doped TiO 2 . It turned out that the synergistic effect between doping P and SOVs on TiO 2 greatly improved transfer and separation efficiency of photogenerated charges, thus significantly enhanced the visible light photocatalytic performance of TiO 2 . Our work would provide an effective way to design new photocatalysts with high performance under visible light irradiation. [ABSTRACT FROM AUTHOR]

With the accelerated application of CeO 2 nanoparticles (NPs), wastewater treatment plants will increasingly receive CeO 2 NPs, thus inevitably causing CeO 2 NPs to encounter microaggregates. Here, we comprehensively elucidate the responses in the structural, physicochemical and microbial properties of wastewater biofilms to chronic exposure (75 days) to different CeO 2 NPs concentrations, with a particular emphasis on the protective mechanisms of stratified extracellular polymeric substances (EPSs). Chronic exposure to 0.1 mg/L CeO 2 NPs boosted the content and broadened the distribution of α- d -glucopyranose polysaccharides (PS), while the sharply increased production and breadth of β- d -glucopyranose PS, forming a formidable shield, was a response to 10 mg/L CeO 2 NPs. After the bacteria were exposed to CeO 2 NPs, loosely bound EPSs (LB-EPSs) aggregated into macromolecules (increasing in apparent molecular weight (AMW)) but at a lower abundance, whereas the average AMW in tightly bound EPSs (TB-EPSs) decreased. The acetyl content and (α-helix+3-turn helix)/β-sheet value of TB-EPSs increased to resist CeO 2 NPs. Furthermore, long-term exposure to CeO 2 NPs decreased cell viability, reduced microbial diversity and shifted the microbial composition. N-acylated- l -homoserine lactone concentrations increased with increased density of Pseudomonas , which was associated with PS-regulated control, thus promoting PS production in EPSs in response to CeO 2 NPs. These results expand the understanding of how microaggregates resist environmental stress caused by NPs. [ABSTRACT FROM AUTHOR]

Twenty-one surface sediments collected from seven surroundings areas of Lake Taihu in two different years were analyzed for total mercury (THg) concentrations, physicochemical characteristics and speciation using a sequential extraction method to assess spatial distribution, sources, and potential ecological risk. Surface sediments from Lake Taihu contained elevated levels of Hg in two sampling years with THg levels ranging from 77 to 346 ng/g (mean 145 ng/g) in October 2010 and ranging from 122 to 573 ng/g (mean 266 ng/g) in November 2012, respectively. The mean THg concentrations in all studied surface sediments exhibited an increasing trend over time. The oxidizable fraction (F3) and residual fraction (F4) were the predominant Hg species in sediments, while more mobile Hg phases of acid-soluble fraction (F1) and reducible fraction (F2) made up less than 0.5% THg. Significant relationships were found between total organic carbon (TOC) and THg and geochemical speciation indicating an important role for organic matter in affecting distribution, mobility, and bioavailability of Hg in sediments. As evidenced by Hakanson's potential risk index the total ecological risk of Hg was low in the entire Lake Taihu in 2010 but considered moderate in Zhushan Bay, West Coast, and Meiliang Bay in 2012. These findings provide conservation managers with information needed to more effectively regulate the environment of Lake Taihu. [ABSTRACT FROM AUTHOR]

Environmental concerns regarding the potential ecological risks of metallic oxide nanoparticles (MNPs) in aquatic ecosystems are increasing; sediment is considered a sink for these MNPs. Although several studies have studied the potential impact of MNPs on microbial communities in freshwater and estuarine sediments, limited information is available regarding the influence of MNPs on the metabolic activity of surficial sediment microbial communities and related biogeochemical conditions. To address these issues, a microcosm approach was established to study the metabolic response of surficial sediment microbial communities to a single addition of TiO 2 or CeO 2 NPs (5 mg/L) using oxygen microelectrodes, enzyme activity measurements, and high-throughput sequencing. Rapid sedimentation of MNPs (regardless of NP type) was observed in freshwater samples, and most (up to 85%) accumulated in surface sediments (<5 mm). Microelectrode profile measurements in pre-incubated sediments treated with MNPs showed that the oxygen concentration decreased at a slower rate with increasing sediment depth compared to that in untreated controls. Biological oxygen consumption in the uppermost sediment layer (0–1500 μm) was significantly inhibited by MNPs, as calculated from steady-state microprofiles, with CeO 2 NPs resulting in enhanced acute toxicity than TiO 2 NPs. High-throughput sequencing showed that MNP exposure increased the bacterial diversity and altered the bacterial community structure, regardless of NP type. The abundance of three dominant bacterial genera, Methylotenera , Cytophagceae_uncultured (classified as an aerobic bacterium), and Cyanobacteria_norank (a facultative bacterium), was markedly reduced by MNPs, which was primarily responsible for inhibiting microbial-mediated oxygen consumption in surficial sediments. In summary, short-term exposure to MNPs negatively affected the metabolic activity of benthic microbial communities, which could influence the biogeochemical functions along the sediment-water interface. [ABSTRACT FROM AUTHOR]

The effect of tetracycline (TC) on the behavior of TiO 2 nanoparticles (NPs) in solution is investigated. The results illustrate that TC molecules do not exhibit an obvious effect on the aggregation of TiO 2 NPs under circumneutral conditions (pH of approximately 5.5). However, the TC molecules exhibit a remarkable effect on the behavior of TiO 2 NPs when the environmental factors (such as pH, ionic strength, and humic acid; HA) are adjusted. In the pH range from 3.0 to 10.0, the zeta potentials of NPs become more positively charged after TC adsorption. The point of zero charge of the TiO 2 NPs increases from 6.5 to 7.5. The stability of the TiO 2 NPs is improved after TC adsorption in different salt solutions. The critical coagulation concentration (CCC) increases from 10.57 mmol/L to 17.21 mmol/L, 4.95 mmol/L to 9.73 mmol/L, and 0.23–1.67 mmol/L in the presence of NaCl, CaCl 2 , and Na 2 SO 4 (where Cl − and SO 4 2− are the counter-ions), respectively. Under different HA concentrations, the C HAPZC (the HA concentration that causes the zeta potential of NPs to be zero) increases from 0.5 mg/L to 1.3 mg/L after TC adsorption. The sizes of the TiO 2 NP aggregates are larger than those without TC adsorption. All of these results are due to an increase in the surface charge of the TiO 2 NPs after TC adsorption. The adsorption of H + during TC adsorption causes protonation of the dimethylamine group on the TC molecules. [ABSTRACT FROM AUTHOR]

In this paper we develop a weak-form integral equation method for an advection–diffusion equation with an unknown pollutant source and unknown initial pollution profile by using Green’s second identity in terms of boundary conditions on the whole space–time boundary. The numerical algorithm is developed to recover the time-dependent pollutant source under an extra final time condition. The iterative algorithm based on coupled closed-form coefficients expansions method can recover the unknown space-dependent pollutant source and initial pollution profile resorting to two extra conditions at different times, which is convergent very fast. Several numerical examples of the inverse pollutant source problem and initial pollution profile problem demonstrate that the present methods are effective and stable against large noise. [ABSTRACT FROM AUTHOR]

Excitation-emission matrix fluorescence spectroscopy combined with parallel factor analysis (EEM-PARAFAC) and two-dimensional correlation spectroscopy (2D-COS) were applied to evaluate the effects of anthropogenic impoundment on the characteristics of dissolved organic matter (DOM) and its heavy metal binding affinity. Three field-sampling cruises conducted in Hongze Lake from 2015 to 2016 were classified as early impoundment and late impoundment cruises according to the hydrological conditions. Five fluorescence components were derived from EEM-PARAFAC, including three humic-like components (C1 C3) and two protein-like components (C4 and C5). The results show a higher dissolved organic carbon concentration, humification degree, molecular size, and level of terrestrial humic-like substances (C1 C3) for early impoundment DOM compared with late impoundment DOM, which were derived from the relatively high inflow discharges present before impoundment. Meanwhile, the relatively high autochthonous contribution and level of protein-like substances found in late impoundment DOM suggested that anthropogenic impoundment can influence the DOM composition in Hongze Lake. Increases in the binding affinities (log K m ) of humic-like substances (C1 and C3) and decreases in the log K m of tryptophan-like substances (C4) were observed during the impoundment period. Additionally, 2D-COS results suggested that the preferential Cu(II) binding ligands in early and late impoundment DOM were tryptophan- (C4) and humic-like (C1) substances, respectively. These results indicated that impoundment-derived DOM composition alteration can decrease the bioavailability and toxicity of Cu in Hongze Lake. The results reported here will improve the understanding of DOM and heavy metal cycling in impoundment lakes. [ABSTRACT FROM AUTHOR]

The methylmercury (MeHg) as the toxic fractions has presented significant threats to biota in freshwater ecosystems. Hg methylation process is demonstrated to be manipulated by biota process (benthic disturbance and algae bloom existence) as well as the abiotic influence (wind fluctuation and illumination intensity) in freshwater ecosystems. However, the mechanisms influencing Hg methylation are still unclear, and the coupled influences of the biotic and abiotic process with the shifts in variation on methylmercury remain unexplored. Accordingly, an annular flume experiment which simulated the freshwater ecosystem, was conducted for 108 days to examine the influences of typical disturbance by chironomid larvae and wind fluctuations on MeHg variation in sediment profiles. The in-situ , passive sampler technique of revealing diffusive gradients in thin films (DGT) encompassed the special resin, based on referenced extraction and coloration-computer imaging densitometry, were employed to obtain labile MeHg, Fe, and S concentrations at high resolution. The results indicate that larval bioturbation during the initial period of the experiment could diminish bioavailable MeHg concentrations and change the diffusion direction of MeHg fluxes. However, this inhibitive effect on MeHg concentrations ceased with larvae eclosion. Compared to bioturbation, wind fluctuation exerted slow but sustained inhibition on MeHg release. Furthermore, the eight parameters (dissolved organic carbon (DOC), DO, labile Fe and S concentrations, pH, sulfate-reducing bacteria (SRB) abundance in sediment, oxidation-reduction potential (ORP) and EC) could explain more of variation in MeHg concentrations which indicated by the canonical correspondence analysis. And these eight parameters manifest higher explanatory power for MeHg distributed in newly formed sediment. More notably, the comparison results of the multiple and simple regression directly demonstrated the DOC was the fundamental and robust factor to control the MeHg variation in the freshwater ecosystem. [ABSTRACT FROM AUTHOR]

Photocatalytic hydrogen evolution is a promising technology in solving the global energy and environment issues. Therefore, it is urgent to develop highly efficient, nonprecious metal and stable photocatalysts. In this work, we synthesized a highly efficient Ni2P–CdS/g-C3N4 composite based on the concept of combining heterojunction engineering with co-catalyst modification. When employed as a photocatalyst for water splitting, the obtained best composite (5% Ni2P–CdS/g-C3N4) displayed dramatically enhanced hydrogen evolution activity at the rate of 44 450 μmol h−1 g−1, which was about 27 times higher than that of pure CdS (1668 μmol h−1 g−1). The apparent quantum yield at 420 nm reaches 46.3%. The excellent photocatalytic activity and stability can be ascribed to the synergistic effect of the intimate contact between CdS and g-C3N4 and the surface co-catalyst modification. Specifically, the g-C3N4 coated on the CdS nanorods can effectively promote the electron−hole pair separation spatially and Ni2P can lower the overpotential of H+ reduction. [ABSTRACT FROM AUTHOR]

As CeO 2 nanoparticles (NPs) are used in many applications, the released particles eventually enter wastewater treatment plants, influencing sludge dewatering and increasing the disposal costs. We conducted tests to gain insight into the sludge dewatering performance and the potential mechanism related to the distribution and production of extracellular polymeric substances (EPS). In addition, we conducted single-factor tests with six concentrations of CeO 2 NPs in sequencing batch reactors containing matured activated sludge. Overall, the specific resistance to filtration (SRF) improved with an increase in the CeO 2 NPs dosage. The SRF significantly increased from 1.460 × 10 12 to 1.632 × 10 12 m/kg after the addition of 5 mg/L CeO 2 NPs ( p < 0.05). The bound water content was enhanced from 2.43 to 2.75 kg/kg dry solid, indicating a deteriorated dewaterability. We found that the increased EPS production, especially the dominant protein ( r = 0.987, p < 0.01), was correlated significantly with the SRF. This is ascribed to the inhibited activity of leucyl aminopeptidase and the reduced adenosine 5′-triphosphate concentrations after exposure to CeO 2 NPs. The fluorescence region integration technique and protein secondary structures revealed the reasons for the poor dewatering performance in the presence of CeO 2 NPs. These are the enhanced amount of soluble microbial by-product-like material and the low value of the α-helix/(β-sheet + random coil). These results could potentially expand the knowledge on sludge dewatering in the presence of NPs. [ABSTRACT FROM AUTHOR]

Construction of water conservation projects may change the transport of water and sediment, and nutrient and food web dynamics in river systems, thus impacting the ecological systems downstream, especially fish habitats. This study proposed an improved habitat model that consider both habitat quality and quantity and applied it to evaluate the impact of water conservancy projects on fish habitats. The indices of fragmentation, which emphasize the core habitat patch, and connectivity, based on the minimum spanning tree, appeared to be the most suitable indicators of fish habitat quality. Chinese Sturgeon ( Acipenser sinensis ) was used as an indicator species and spawning sites between the Gezhouba Dam and Yichang Station were selected as study areas. The relationships between habitat quality and water temperature and discharge were established in these areas. The results indicated that discharges from 13,100 m 3 /s to 24,200 m 3 /s and water temperatures from 17.1 °C to 20.0 °C are recommended for Chinese sturgeon spawning and hatching. The improved habitat model showed that the impoundment and operation of the Three Gorges Dam and the construction of the separation levee project both caused a decrease in the habitat quality of Chinese sturgeon spawning sites. Compared to previous studies, the improved habitat model provides a promising intermediate step to reduce the uncertainty in evaluating and quantifying the impact of water conservation projects on fish habitats. [ABSTRACT FROM AUTHOR]