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[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]

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]

Despite previous efforts and the rapid progress on elucidating the impact of perfluorooctanesulfonate (PFOS) on the environment, its effects on riparian plants, a key component of aquatic ecosystems, are still poorly understood. A 48-day hydroponic experiment was carried out on two typical riparian species (Acorus calamus and Phragmites communis) to examine the toxic effects of PFOS on these plants. The results showed that, at high concentration (more than 10 mg L−1), PFOS could prevent chlorophyll accumulation (reduced by 13.7–22.2% at 10 mg L−1 PFOS and 22.4–30.0% at 50 mg L−1 PFOS for 48 days) and soluble protein synthesis (reduced by 2.3–9.0% at 10 mg L−1 PFOS and 10.6–26.8% at 50 mg L−1 PFOS for 48 days). Contrastingly, less than 1 mg L−1 of PFOS could induce chlorophyll accumulation (increased by 18.6% in A. calamus roots, 11.3% in A. calamus leaves, and 13.6% in P. communis roots at 1 mg L−1 PFOS for 3 days) and soluble protein synthesis (increased by 6.1% in A. calamus roots, 18.4% in A. calamus leaves, 9.7% in P. communis roots, 23.4% in P. communis stems, and 24.0% in P. communis leaves, at 1 mg L−1 PFOS for 6 days). In addition, PFOS led to oxidative stress, as revealed by the elevated concentrations of malonaldehyde and hydrogen peroxide, and reduced the activities of antioxidant enzymes such as superoxide dismutase (reduced by 10.3% in P. communis stems at 50 mg L−1 PFOS for 48 days), catalase (reduced by 20.6–50.3% in test species at 50 mg L−1 PFOS for 48 days), and peroxidase (reduced by 24.9–37.7% in test species at 50 mg L−1 PFOS for 48 days). The biomarkers of both plants changed rapidly in the first half of the experiment (0–24 days) and stabilized in the second half of the experiment (24–48 days). The risk and related factors of PFOS on riparian plants were evaluated by using these biomarkers. Experiments showed that P. communis was more resistant to low concentration (<10 mg L−1) of PFOS than A. calamus. • The phytotoxicity of PFOS on two riparian plants was studied. • PFOS affects chlorophyll and soluble protein levels in A. calamus and P. communis. • PFOS inhibits CAT, SOD, and POD activities in test riparian plants. • Values of the biomarkers were integrated to assess the effects of PFOS on two plants. [ABSTRACT FROM AUTHOR]

Abstract Bacterioplankton communities play a critical role in ecological processes in river systems, and shifts of their composition may impact microbial levels and raise public health concerns. The aim of this study was to comprehensively analyze the essential factors influencing bacterioplankton community, along with pathogen, and to estimate the health risk caused by the pathogens downstream of the Liushahe River, which is located in the famous touristic city Xishuangbanna. Results showed that wastewater treatment plants (WWTPs) and a subtropical recreational park impacted the bacterioplankton community and pathogen population, and potential pathogen identification demonstrated that 76 of 145 reference genera were present in the river. Moreover, the bacterioplankton community and pathogen were differently impacted by environmental gradients, and SRP, NO 2 and pH were main factors influencing bacterioplankton community while pathogen population was highly correlated with temperature and turbidity. In addition, it is noted that the pathogen population was dominated by bacterioplankton community and this might because the capacity of resistance invasion pathogen was determined by of bacterioplankton community diversity. Therefore, bacterioplankton community diversity can be used to control and predict the amount of pathogens. Quantitative microbial risk assessment (QMRA) also revealed that the infection risks of Escherichia coli (E. coli), Mycobacterium avium (M. avium), and Pseudomonas aeruginosa (P. aeruginosa) during five recreational activities, especially water-based activities in the touristic city, were greater than that in natural areas and mostly exceeded the U.S. EPA risk limit for recreational activities. Our study offered the first insight into the potential relationship between the bacterioplankton community and bacterial pathogens within a touristic river. Graphical abstract fx1 Highlights • Changes in river bacterioplankton communities may increase pathogen levels. • Bacterial community and pathogens shift differently under environmental stresses. • Temperature adjustment may control pathogen without alter bacterioplankton community. • The diversity of bacterioplankton community may dominate the pathogens populations. • This study may be used to warn visitors and improve river management in touristic area. [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]

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]

The behaviors of nanoparticles rely on the aqueous condition such as natural organic matter (NOM). Therefore the presence of NOM would influence the interaction of nanoparticles with other substances possibly. Here, microcystin-LR (MC-LR) adsorption on iron oxide nanoparticles (IONPs) was studied in an aqueous solution with different types of NOM, including extracellular polymeric substances (EPS) from cyanobacteria and alginic acid sodium salt (AASS) from brown algae. Results revealed that EPS played an important role in stabilizing IONPs and in the toxin adsorption efficiency. The stability of IONPs was heavily depended on the concentration and type of NOM, which can affect the surface charge of IONPs significantly in solution. The enhanced stability of IONPs was due to the electrostatic interactions. Adsorption kinetics and isotherm studies confirmed that NOM can affect the IONPs’ adsorption efficiency, and pseudo-second-order kinetics better explained this process. The removal efficiency for MC-LR decreased in the presence of NOM (Control > EPS-M1 > AASS > EPS-M9), indicating that NOM and MC-LR compete for limited adsorption sites. The presence of NOM in a eutrophic environment stabilized the IONPs while inhibiting the MC-LR removal efficiency. This investigation emphasized the negative effect of cyanobacterial EPS on the removal of microcystins when using magnetic separation technology. And this results could also be used to model the transportation of iron minerals carrying toxic substances in aqueous environment. [ABSTRACT FROM AUTHOR]

Harmful cyanobacterial blooms have been observed in various water bodies all over the world and their secondary metabolite, microcystins (MCs), have threatened aquatic organisms and human health. Meanwhile, iron is one of the key nutrients for algal growth due to its important role in many physiological functions. In our study, different iron regimes were set to investigate their effects on physiological indices and gene expressions of MC biosynthesis in toxic Microcystis aeruginosa . The results showed that iron addition promoted algal growth and chlorophyll- a (Chl- a ) production. Photosynthetic capacity was inhibited under iron limitation, which blocked the electron transport chain, intensified the production of reactive oxygen species (ROS) and further damaged algal antioxidant defensive system in cells. Moreover, unsynchronized changes of microcystin-leucine-arginine (MC-LR) level and mcy gene expressions were observed in all iron regimes. Interestingly, despite that the intracellular quantity of MC-LR under iron limitation was less than that under iron-replete condition, the potential toxicity was greater in the former. Iron variation had little influence on the excretion of the toxin, which can be further confirmed by scanning electron microscopic observations. In consequence, we propose an indirect influence of iron on MC biosynthesis that starts with the decreased photosynthetic capacity and energy production by iron limitation, followed by the damaged electron transport in cells, and eventually causes the variation of mcy gene expressions due to energy shortage. Therefore, our study has provided the evidences for the close relationship between iron variation and MC biosynthesis in M. aeruginosa , suggesting that iron should be taken into account during the monitoring of harmful algal blooms in the future. [ABSTRACT FROM AUTHOR]

Aquatic sediments are believed to be an important sink for carbon nanotubes (CNTs). With novel properties, CNTs can potentially disturb the fate and mobility of the co-existing contaminants in the sediments. Only toxic pollutants have been investigated previously, and to the best of our knowledge, no data has been published on how CNTs influence phosphorus (P) adsorption on aquatic sediments. In this study, multi-walled carbon nanotubes (MWCNTs) were selected as model CNTs. Experimental results indicated that compared to pseudo-first order and intraparticle diffusion models, the pseudo-second-order model is better for describing the adsorption kinetics of sediments and MWCNT-contaminated sediments. Adsorption isotherm studies suggested that the Langmuir model fits the isotherm data well. With the increase in the MWCNT-to-sediment ratio from 0.0% to 5.0%, the theoretical maximum monolayer adsorption capacity (Q max ) for P increased from 0.664 to 0.996 mg/g. However, the Langmuir isotherm coefficient (K L ) significantly decreased from 4.231 L/mg to 2.874 L/mg, indicating the decrease in the adsorption free energy of P adsorbed on the sediments after MWCNT contamination. It was suggested that P was released more easily to the overlying water after the re-suspension of sediments. Moreover, the adsorption of sediments and sediment-MWCNT mixture was endothermic and physical in nature. Results obtained herein suggested that the change in the specific surface area and zeta potential of sediments is related to MWCNT contamination, and the large adsorption capacity of MWCNTs is probably the main factor responsible for the variation in the adsorption of P on aquatic sediments. [ABSTRACT FROM AUTHOR]

In this work, flower-like Au/Bi 2 O 2 CO 3 /Bi 2 O 3 multi-heterojunction photocatalysts were prepared by a in-situ growth method. The as-prepared samples were characterized by different techniques including Transmission Electron Microscopy (TEM), X-ray diffraction (XRD), UV–vis diffuse reflectance spectrometry (DRS), X-ray photoelectron spectroscopy (XPS), Photoluminescence (PL) and photo-induced current. The photocatalytic performance of the as prepared samples was evaluated by degradation of rhodamine B (RhB) under visible light (λ > 400 nm). Au/Bi 2 O 2 CO 3 /Bi 2 O 3 exhibited much higher activity than pure Bi 2 O 2 CO 3 or Bi 2 O 2 CO 3 /Bi 2 O 3 . The rate constant of best one Au/Bi 2 O 2 CO 3 /Bi 2 O 3 sample is 100 and 14 times as that of pure Bi 2 O 2 CO 3 and β-Bi 2 O 3 /Bi 2 O 2 CO 3 , respectively. The enhanced photocatalytic activity of Au/Bi 2 O 2 CO 3 /Bi 2 O 3 can be ascribed to the surface plasmon resonance (SPR) effects of Au nanoparticles and the formed multi-heterojunctions, which enhanced the absorbance of visible light and facilitated the transferring and separation of photogenerated electron-hole pairs, respectively. [ABSTRACT FROM AUTHOR]

The co-presence of perfluorooctane sulfonate (PFOS) and phosphate in wastewater of various industries has been detected. Removing PFOS and phosphate simultaneously before discharging sewage into natural water can decrease effectively the environmental risk caused by the combined pollution of PFOS and phosphate. In this study, laboratory batch experiments were conducted for investigating the co-adsorption of PFOS and phosphate on boehmite and the influences of temperature, phosphate initial concentration and pH on the co-adsorption. The adsorption thermodynamics and kinetics of PFOS and phosphate on boehmite were also investigated completely and systematically. The results showed that lower temperature favored the co-adsorptions of PFOS and phosphate. The adsorption of PFOS and phosphate on boehmite agreed well with the Langmuir isotherm and the adsorption parameters of thermodynamics are ΔH=−16.9 and −20.0 kJ mol −1 (PFOS and phosphate), ΔS=−5.69 and −7.63 J mol −1 K −1 (PFOS and phosphate) and ΔG <0 (PFOS and phosphate). It demonstrated that the co-adsorption of PFOS and phosphate on boehmite is a spontaneously exothermic process. Moreover, the co-adsorption process can be described well by a pseudo-second-order kinetic model. With increasing phosphate initial concentration, more phosphate could be adsorbed on boehmite, while the adsorption of PFOS decreased at phosphate initial concentration of less than 30 mg L −1 and increased at that of larger than 30 mg L −1 . In the co-adsorption process, the adsorption amount of PFOS decreased with pH increasing, but that of phosphate changed little. [ABSTRACT FROM AUTHOR]

Metal resistance genes (MRGs) are potential bio-indicators to diagnose contamination stress on riverine ecosystems. Within reservoir systems, river damming weakens hydrodynamic condition and enriches metal contaminants. But, little is known about the synergic impacts of geographic variation and anthropogenic pollution on MRGs. In this study, the abundance, composition and microbes of MRGs in four cascade reservoirs along the Jinsha River, southwestern China were investigated via high-throughput metagenomics. The results showed significant enrichment of chromium, cadmium and lead in Ludila and Xiluodu reservoirs with moderate ecological risks based on the criteria of drinking water quality and aquatic life protection. Nevertheless, at watershed scale, these metals played little role in up-regulating MRGs abundance owing to the limited toxic stress on microbes. Accordingly, geographic variation showed stronger impacts on MRGs composition than metals as revealed by the distance-decay relationship (Pearson correlation, r geo = 0.24–0.57, r metal = 0.10–0.41) and co-occurrence network (Node degree to MRGs subtype, n geo = 180, n metal = 6). River damming, as an artificial isolation of geographic space, significantly affected MRGs composition. The longer operation history, smaller storage capacity and higher regulation frequency caused the higher dissimilarity of MRGs composition between the reservoir's upstream and downstream areas. In conclusion, the metal pollution level is a prerequisite regulating MRGs; while under the lowly-polluted conditions, geographic variation had stronger impacts on MRGs than metal pollution via altered assembly of microbial communities. This study provides an important guidance for the future environmental management and ecological protection of river-reservoir ecosystems. • Metal pollution level is a prerequisite regulating MRGs abundance in reservoir water. • Geographic variation had stronger impact on MRGs composition than metal pollution. • Reservoir operation time, storage size and regulation mode affected MRGs abundance. • Reservoir MRGs distribution was internally affected by relevant microbial community. [ABSTRACT FROM AUTHOR]

The presence of ZnO nanoparticles (ZnO NPs) in natural waters has raised concerns about their environmental impacts, but the potential influences of ZnO NPs on fluvial biofilm have not been reported. In this study, the utility of antioxidant enzyme activities (AEA) as biomarkers of fluvial biofilm to ZnO NPs toxicity and a method that combines AEA into an index of “Integrated Biomarker Responses (IBR)” were studied. Compared with the absence of ZnO NPs, scanning electron microscopy (SEM) images revealed that a large amount of ZnO NPs were adsorbed onto biofilm and these NPs exerted adverse effects on the viability of bacteria in biofilm. The production of reactive oxygen species (ROS) with high concentrations (30 and 100 mg/L) of ZnO NPs exposure reached to 184% and 244% of the control, while no cell leakage and membrane damage were observed. After exposure to ZnO NPs for 0.25 and 3 days, the activities of catalase (CAT), superoxide dismutase (SOD) and glutathione reductase (GR), glutathione peroxidase (GSH-Px) were significantly increased, respectively. At the end of exposure period (21 days), the AEA with the presence of 1 mg/L ZnO NPs exposure were comparable to the control, while most of those in high concentrations of ZnO NPs were decreased. The results of IBR showed that the biofilm can adapt to 1 mg/L ZnO NPs exposure, while be seriously damaged by 30 and 100 mg/L ZnO NPs after 3 and 0.25 days. IBR can be used as an appropriate evaluation system of the toxicity effects of ZnO NPs on fluvial biofim. [ABSTRACT FROM AUTHOR]

Toxic cyanobacterial blooms have occurred in various water bodies during recent decades and made serious health hazards to plants, animals and humans. Iron is an important micronutrient for algal growth and recently, the concentration of which has increased remarkably in freshwaters. In this paper, the cyanobacterium Microcystis aeruginosa FACHB-905 was cultivated under non-iron (0 μM), iron-limited (10 μM) and iron-replete (100 μM) conditions to investigate the effects of iron on growth, antioxidant enzyme activity, EPS and microcystin production. The results showed that algal cell density and chlorophyll- a content were maximal at the highest iron concentration. Antioxidant enzymes activity increased notably under all three conditions in the early stage of experiment, of which the SOD activity recovered soon from oxidative stress in 10 μM group. The productions of some protein-like substances and humic acid-like substances of bound EPS were inhibited in iron-containing groups in the early stage of experiment while promoted after the adaptation period of Microcystis aeruginosa . Iron addition is a factor affecting the formation of cyanobacterial blooms through its impact on the content of LB-EPS and the composition of TB-EPS. The intracellular MC-LR concentration and the productivity potential of MC-LR were the lowest in 0 μM group and highest in 10 μM group. No obvious extracellular release of MC-LR was observed during the cultivation time. Therefore, iron addition can promote the physiological activities of M. aeruginosa , but a greater harm could be brought into environment under iron-limited (10 μM) condition than under iron-replete (100 μM) condition. [ABSTRACT FROM AUTHOR]

Perfluorinated compounds (PFCs) can pose adverse effect on aquatic species and community structure. However, little is known about how the characteristics of molecules of PFCs affect their chronic toxic potencies to aquatic species, and the species sensitivity distributions (SSDs) and ecological risk assessments of PFCs are hampered by limited available data of chronic toxicity. In the present study, a novel procedure is proposed to obtain the ecological risk of PFCs using existing exposure concentrations of PFCs and SSDs integrated with the chronic toxicity prediction through robust QSAR models. The results showed that the energy of the lowest unoccupied molecular orbital (E LUMO) exhibited the strongest correlation with the chronic toxicities of 15 PFCs (R 2 > 0.844, F > 16.206, p < 0.05). SSDs of 15 PFCs on eight species were first constructed, and the SSD fitting parameters were significantly correlated with E LUMO (R 2 > 0.610, F > 19.471, p < 0.05). The QSAR-SSDs support the evaluation of hazardous criteria of PFCs for which data are lacking. Given environmental exposure distributions (EEDs) of the national presence of PFCs in aquatic systems in China, the QSAR-SSDs models allow the development of the ecological risk assessment for PFCs. This way, it was concluded that negligible environmental risk (defined as 5% of the species being potentially exposed to concentrations able to cause effects in < 5% of the case) could be expected from exposure to PFCs in surface waters in China. This method may be helpful for providing an evidence-based approach to guide the risk management for PFCs in aquatic environment. • Molecular descriptor, E LUMO showed the strongest correlation with log-NOEC/LOEC. • HC 5 and its 95% confidence intervals of 15 PFCs were predicted by QSAR-SSD. • Molecular descriptors can be directly used to estimate SSD parameters for PFCs. • Acceptable environmental risk expected from exposure to PFCs. [ABSTRACT FROM AUTHOR]

In this study, magnetic graphene oxide-loaded Ce-doped titania (MGO–Ce–TiO 2 ) hybridized composite was prepared by a facile method. The as-prepared samples exhibited good adsorption capacity, high visible-light photoactive and magnetic separability as a novel photocatalyst in the degradation of tetracyclines (TC). The intermediate products and photocatalytic route of TC were proposed based on the analysis results of LC–MS. Moreover, the repeatability of the photoactivity with the use of MGO–Ce–TiO 2 was investigated in the multi-round experiments with the assistance of an applied magnetic field. Therefore, the prepared composite photocatalysts were considered as a kind of promising photocatalyst in a suspension reaction system, in which they can offer effectively recovery ability. The effect of MGO content on the photocatalytic performance was also studied, and an optimum content was obtained. [ABSTRACT FROM AUTHOR]

Dam construction causes phosphorus (P) accumulation in reservoir sediments and significantly affects the generation of available P. However, the effect of dam construction on the activity of sediment alkaline phosphatase (ALP), which is encoded by the bacterial phoD gene and participates in P mineralization, in river sediments remains unclear. Here, we investigated the ALP activities in 78 sediment samples collected from the cascade reservoir regions located in the Lancang River and the Jinsha River, two highly regulated rivers in southwestern China. The abundance and community composition of phoD -harboring bacteria were determined based on the phoD gene using quantitative real-time PCR and MiSeq sequencing, respectively. Comparison of control and affected sites indicated that dam construction significantly increased sediment ALP activity in both rivers. The abundances of phoD -harboring bacteria increased and their community compositions varied in response to dam construction; the relative abundances of the dominant genera Methylobacterium and Bradyrhizobium were particularly higher in affected site than control site. Co-occurrence network analyses revealed much higher network connectivity and relative abundances of keystone species in affected sites. Some microbial factors including phoD -harboring bacterial abundances, network clustering coefficients, and relative abundance of keystone species were positively correlated with ALP activity. The relative abundance of keystone species was identified as the most important microbial factor contributing to variation in ALP activity based on structural equation modeling analysis. These findings enhance our understanding of how dam construction affects the functions of phoD -harboring bacteria and their role in the P biogeochemical cycle in highly regulated rivers. • Sediment alkaline phosphatase activity was markedly enhanced by dam construction. • Damming altered the abundance and community composition of phoD -harboring bacteria. • Damming enhanced connectivity and cooperation in phoD -harboring bacterial network. • Keystone species of phoD -harboring bacteria were enriched in reservoir sediments. [ABSTRACT FROM AUTHOR]

The long-term effects of Ni(II) on substrate removal and microorganism activities were investigated by operating sequencing batch reactors (SBRs). Compared to the control system lacking Ni(II), the removal efficiencies of total organic carbon (TOC) and ammonium nitrogen (NH4 +-N) in SBR system loading with 10mgL−1 Ni(II) decreased drastically from 90.2±3.6 percent to 75.0±8.9 percent, and 99.2±0.6 percent to 50.8±11.5 percent, respectively. As compared to the control system, a inhibitory rate of more than 50 percent for the 2,3,5-triphenyltetrazolium chloride electron transport system (TTC-ETS) and the 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyltetrazolium chloride electron transport system (INT-ETS), and 43 percent for the specific oxygen uptake rate (sOUR) were detected in SBR system loading with 20mgL−1 Ni(II). TTC-ETS, INT-ETS, and sOUR were significantly correlated with substrate removal efficiencies, suggesting that they could all serve as effective indicators of the performance of activated sludge processes. Additionally, INT-ETS is superior to sOUR and TTC-ETS in detecting the toxic effects of Ni(II) on sludge microorganism activity. [ABSTRACT FROM AUTHOR]

The effects of Pb on photosynthetic pigments, oxidative stress and antioxidant response were assayed using biochemical and histochemical methods in leaves of Vallisneria natans (Lour.) Hara treated with 0–100μM Pb2+ for 0–6d. The Pb content increased with the increase of exposure duration and a highest Pb uptake value (about 9.4mg Pbg−1 dry weight) was obtained at 6d. Pb induced the accumulation of H2O2 and O2 −. The increase of malondialdehyde content and the decrease of total chlorophyll and carotenoids were detected in V. natans under Pb stress. Activities of NAD(P)H oxidase, guaiacol peroxidase, glutathione reductase and ascorbate peroxidase increased at 75μM Pb2+ for 2–6 days, while activities of superoxide dismutase and catalase and the content of ascorbic acid increased within two days in plants exposed to 75μM Pb2+ and decreased thereafter. The Pb uptake and accumulation mechanism were discussed. [Copyright &y& Elsevier]

For better understanding the metabolic adaptations to Pb stress in submerged plants, the alterations in mineral elements uptake and in secondary metabolism were studied in leaves of Vallisneria natans (Lour.) Hara exposed to 0–100μM Pb for 0–7d. Pb content increased in leaves in a dose-dependent way. The increase of calcium, magnesium and iron content and the decrease of phosphorus, potassium and manganese content were detected in leaves of V. natans under Pb stress, while no significant changes were detected in copper and zinc concentration. Meanwhile, there was an increase in the concentrations of total phenolic and flavonoids. Pb treatment caused an increase in the catalytic activities of shikimate dehydrogenase, phenylalanine ammonialyase and polyphenol oxidase. The results suggest that nutrient uptake and secondary metabolism were actively regulated by V. natans plants in response to Pb stress. [Copyright &y& Elsevier]

Riverine bacterioplankton are highly responsive to river alterations and their abundant and rare sub-communities may have different roles in biogeochemical cycling. However, with the rapid development of dam constructions, our knowledge on adaptation mechanism of these sub-communities in regulated river ecosystem was still limited, especially with regard to their functional traits. Here, our study was conducted in the 2800 km Yarlung Tsangpo River on the Tibetan Plateau to address the question of how abundant and rare bacterioplankton would respond taxonomically and functionally to river damming using 16S rRNA gene sequencing combined with Geochip microarray technique. Our results showed that abundant sub-community dominated taxonomic composition while rare sub-community largely determined functional composition. It is also observed that taxonomic diversity of abundant sub-community was significantly stimulated in the reservoir while that of rare sub-community was markedly inhibited. Moreover, abundant sub-community exhibited functional redundancy under damming disturbances since altered taxonomic composition and unaltered functional composition co-occurred simultaneously. Meanwhile, due to portfolio effect, rare sub-community maintained a greater stability under damming disturbances with little variation in taxonomic and functional compositions. In addition, the Stegen null model analysis revealed that stochastic process governed community assembly in both abundant and rare sub-communities. However, according to source tracking analysis, the taxonomic dispersion of abundant sub-community was less significantly impeded by the dam while the functional dispersion of rare sub-community was less strongly interrupted, indicating that the dispersal process in the dominated sub-community was less susceptible to damming. Therefore, by considering bacterioplankton functional traits, our study provided comprehensive evidences for the distinct strategies of abundant and rare sub-communities in response to damming. • 16S rRNA gene sequencing and Geochip microarray data sets were matched. • Total taxonomy and functional traits were determined by different sub-communities. • Abundant sub-community exhibited functional redundancy in response to damming. • Rare sub-community maintained a greater stability due to portfolio effect. • Dispersal process of the dominated sub-community was less susceptible to damming. [ABSTRACT FROM AUTHOR]

River damming has raised controversial concerns as it simultaneously contributes to socioeconomic development but may jeopardize aquatic ecology. Since bacterioplankton catalyze vital biogeochemical reactions and play important roles in aquatic ecosystems, more attention has been paid to their responses in dammed rivers. Here, a comparative study was conducted between single-dammed (the Yarlung Tsangpo River) and cascade-dammed (the Lancang River) rivers in Southwest China to investigate whether bacterioplankton respond equally to different river regulations. Our results showed that the decreased bacterioplankton abundance and the increased α-diversity always co-occurred in reservoirs of the Yarlung Tsangpo River and the Lancang River. However, the impact of damming on bacterioplankton abundance and α-diversity were resilient in the Lancang River, which can be attributed to the repeated alterations of environmental heterogeneity in cascade damming reaches. Meanwhile, a generalized additive model (GAM) was applied to identify the important drivers affecting bacterioplankton variation. The abundance was influenced by trophic conditions, such as dissolved silicon, while α-diversity was closely related to the microbial dispersal process, such as elevation and distance-from source. And it is also noted that the bacterioplankton dispersal process was interrupted in cascade damming reaches. In addition, based on their important drivers, variations in abundance and α-diversity were also predicted by GAM. As revealed by the quantitative mutual validation between the two rivers, abundance and α-diversity in the cascade-dammed river can be predicted by their response to single-dammed river, suggesting that the impact of cascade damming on bacterioplankton can be pre-assessed by referring to the single stage damming effect. Therefore, our study provides the first trial of quantitative evidence that bacterioplankton do not respond equally to different river regulations, and the impact of cascade damming on bacterioplankton can be predicted based on single stage damming effect, which can contribute to the protection of aquatic ecology in the cascade hydropower development. • Damming led to decreased abundance and increased α-diversity in reservoirs. • Impact of dam on abundance and α-diversity was resilient in cascade-dammed river. • Bacterioplankton dispersal process was interrupted in cascade damming reaches. • Bacterioplankton in cascade-dammed river can be pre-assessed by single-dammed GAM. [ABSTRACT FROM AUTHOR]

Graphical abstract Novel Z-scheme AgI/Ag/Bi 3 TaO 7 photocatalysts with excellent visible light responsive performance were prepared for the first time. The as-obtained photocatalysts showed significantly enhanced activity for different organic pollutants degradation (antibiotics and dyes) under visible light irradiation. The optimum apparent rate constant reached up to 212 times as high as that of pure Bi 3 TaO 7 for the degradation of sulfamethoxazole. Abstract In this work, novel Z-scheme AgI/Ag/Bi 3 TaO 7 photocatalysts with excellent visible light responsive performance were prepared by a facile hydrothermal reaction combined with ultrasonic assisted precipitation-photoreduction process. The samples were characterized by X-ray power diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-absorption spectra, electrochemical impedance spectroscopy (EIS) and photoluminescence (PL). The photocatalytic performance of AgI/Ag/Bi 3 TaO 7 composites was assessed by the decomposition of sulfamethoxazole (SMZ) under visible light irradiation. The experimental results revealed that AgI/Ag/BTO-2 showed the best photocatalytic activity for degradation of SMZ (the apparent rate constant was 212 times as high as that of pure Bi 3 TaO 7). The results also showed that the as-prepared AgI/Ag/Bi 3 TaO 7 sample exhibited high activity for the degradation of other organic pollutants (oxcarbazepine, RhB and X-3B). A probable mechanism on the enhanced photocatalytic performance was put forward based on the results of band structure, radicals trapping tests and ESR. In addition, the implanted metallic Ag acted as charge transfer bridge played an important role in the formation of a stable Z-scheme AgI/Ag/Bi 3 TaO 7 system with powerful redox ability. This study offers a good example for the design and development of new efficient visible light responsive photocatalysts for organic pollutants degradation. [ABSTRACT FROM AUTHOR]

The extended DLVO (XDLVO) theory was applied to elucidate the potential effects of CeO 2 nanoparticles (CeO 2 NPs) on sludge aggregation and the role of extracellular polymeric substances (EPS). In this study, seven different concentrations of CeO 2 NPs were added to activated sludge cultured in sequencing batch reactors (SBRs) and compared with a control test that received no CeO 2 NPs. After exposure to 50 mg/L CeO 2 NPs, a negligible change ( p >0.1) occurred in the sludge volume index (SVI), whereas the flocculability and aggregation of the sludge decreased by 18.8% and 11.2%, respectively, resulting in a high effluent turbidity. The XDLVO theory demonstrated that the adverse effects of the CeO 2 NPs on sludge aggregation were due to an enhanced barrier energy. Compared to the van der Waals energies (W A ) and the electric double layer (W R ), the acid-base interaction (W AB ) markedly changed for the various concentrations of CeO 2 NPs. The EPS played a decisive role in the sludge surface characteristics, as the removal of EPS equals to the negative effects induced by 5–10 mg/L CeO 2 NPs on the sludge flocculability and aggregation. The presence of CeO 2 NPs induced negative contributions to the tight boundary EPS (TB-EPS) and core bacteria while positive contributions to the total interaction energy of the loose boundary EPS (LB-EPS). [ABSTRACT FROM AUTHOR]

In this work, BiOCl modified titanium phosphate nanoplates (BiOCl/TP) composite photocatalysts with p-n heterojunctions were prepared by a in-situ growth method. The morphology, crystal structure and optical properties of the prepared samples were characterized by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray diffraction (XRD), UV–vis diffuse reflectance spectrometry (DRS). Rhodamine B (RhB), reactive brilliant Red X-3B (X-3B), methylene blue (MB), ciprofloxacin (CIP) and phenol were used to investigate the photocatalytic performance of the prepared samples under ultraviolet light irradiation. Results showed that the BiOCl/TP exhibited much higher activity for the degradation of all these model organic pollutants than pure TP. The mechanism for the enhancement of the photocatalytic performance was established with the help of the results of photocurrent measurements and Photoluminescence spectra. The results illustrated that the enhanced activity could be attributed to the formation of p-n heterojunctions between p-type BiOCl and n-type titanium phosphate, which effectively suppressed the recombination of photo-induced electron-hole pairs. Furthermore, the possible photocatalytic mechanisms on the degradation of the organic pollutants were also proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel metallic and non-metallic co-doped polymeric g-C 3 N 5 was fabricated. • K and I co-doping g-C 3 N 5 improved the photocatalytic H 2 O 2 production activity. • DFT calculations indicated that O 2 molecules serve as the electron trap sites. • K and I co-doping g-C 3 N 5 enhanced the adsorption and activation capacity of O 2. Graphite carbon nitride (g-C 3 N 5) has been widely used in various photocatalytic reactions due to its higher thermodynamic stability and better electronic properties compared to g-C 3 N 4. However, it is still challenging to endow g-C 3 N 5 with high performance on photocatalytic hydrogen peroxide (H 2 O 2) production. Herein, potassium and iodine are co-doped into g-C 3 N 5 (g-C 3 N 5 -K, I) for photocatalytic production of H 2 O 2 with high efficiency. As expected, the photocatalytic H 2 O 2 production rate over the g-C 3 N 5 -K, I (2933.4 μM h−1) reaches to 84.22 times as that of g-C 3 N 5. The excellent photocatalytic H 2 O 2 production activity is mainly ascribed to the co-doping of K and I, which significantly improves the capacity of oxygen (O 2) adsorption, selectivity of two-electrons oxygen reduction reaction (2e− ORR) and separation efficiency of charge carriers. The density functional theory (DFT) calculations reveal that O 2 molecules are more conducive to being adsorbed on g-C 3 N 5 -K, I. Besides, the result of excited states further indicates that photo-generated electrons can be directionally driven to the adsorbed O 2 molecules, which are effectively activated to form H 2 O 2. The findings will contribute to new insights in designing and synthesizing g-C 3 N 5 based photocatalysts for the H 2 O 2 production. [ABSTRACT FROM AUTHOR]

Photocatalytic technology is an attractive and promising approach for nitenpyram degradation; however, how to ensure the carrier separation efficiency and catalytic sites exposure is still great challenges. In this study, we construct CdS@MoS 2 (CM) nanohybrids with a 3D hierarchical configuration to enhance the separation and transfer efficiency of the photo-induced electron by a covalent-anion-driven self-assembly method. The vertical orientation of MoS 2 ultrathin nanosheets not only provides a large specific surface area for the oxidation and reduction reactions but also enables the active edge sites of MoS 2 to be maximally exposed. As a result, this structure drastically facilitates the exposure of the catalytic active region and the performance of the carrier transfer and injection into photocatalytic degradation for nitenpyram (NTP). The optimal CdS–MoS 2 has an impressive and stable NTP removal efficiency with a high reaction rate constant up to 0.078 min−1, which is 3.25 times higher than that of pure cadmium sulfide. The photocatalytic degradation mechanism and degradation pathway of NTP were presented by synthesizing the results of experimental analysis and density flooding theory (DFT) calculations. In further, for the first time, the cytotoxicity and genotoxicity of NTP on moving bed biofilm reactors (MBBRs) was disclosed and a continuous photocatalytic wastewater pretreatment device based on the CM is proposed for the stable biological nitrogen removal activity of MBBRs, which can degrade more than 80% NTP per hour. • The composite photocatalyst was constructed by covalent-anion-driven self-assembly method. • Compared with pure CdS, the photogenerated carrier separation efficiency of CdS@MoS 2 (CM) was enhanced by 4.8 times. • The composite exhibited significantly activity for NTP degradation. • The degradation pathways were precisely predicted based on experimental analysis and DFT calculations. [ABSTRACT FROM AUTHOR]

Antibiotic contamination and excessive nitrate loads are generally concurrent in aquatic ecosystems. However, little is known about the effects of nitrate input on the biodegradation of antibiotics. In this study, the effects of nitrate input on microbial degradation of erythromycin, a typical macrolide antibiotic widely detected in lake sediments, were investigated. The results showed that the nitrate input significantly inhibited the erythromycin removal and such an inhibitory effect was strengthened with the increased input dosages. Nitrate input significantly increased sediment nitrite concentration, indicating enhanced denitrification under high nitrate pressure. Bacterial network module and keystone species analysis showed that nitrate input enriched the keystone species involved in denitrification (e.g., Simplicispira and Denitratisoma). In contrast, some potential erythromycin-degrading bacteria (e.g., Desulfatiglandales, Pseudomonadales, Nitrospira) were inhibited by nitrate input. The variations in dominant bacterial groups implied competition between denitrification and erythromycin degradation in response to nitrate input. Based on the partial least squares path modeling analysis, keystone species (total effect: 0.419) and bacterial module (total effect: 0.403) showed strong association with erythromycin removal percentage. This indicated that the inhibitory effect of nitrate input on erythromycin degradation was mainly explained by bacterial network modules and keystone species. These findings will help us to assess the bioremediation potential of antibiotic-contaminated sediments suffering from excessive nitrogen discharge concurrently. [Display omitted] • Nitrate input inhibited erythromycin biodegradation by enhancing denitrification. • Denitrification may compete for electrons with erythromycin reduction. • Nitrate inhibited potential erythromycin-degrading bacteria (e.g., Nitrospira). • Denitrifying bacteria (e.g., Denitratisoma) were enriched by nitrate input. • Nitrate inhibitory effect was mainly explained by keystone species and modules. [ABSTRACT FROM AUTHOR]

Pharmaceuticals and personal care products (PPCPs) are recognized as a group of emerging contaminants closely related to anthropogenic activities, which capture increasing attention worldwide. To evaluate the anthropogenic disturbances on PPCP distribution and sources, this study investigated the distribution and sources of 50 PPCPs along the 2300 km long Jinsha River and revealed different anthropogenic disturbances on PPCPs. Results showed that 40 out of the 50 PPCPs were ubiquitously detected among these river water samples, with the concentrations varied from less than 1 ng/L to more than 500 ng/L. Although most PPCPs concentrations were much lower in the Jinsha River than in highly developed rivers, the prevalence of PPCPs suggested the widespread use and improper disposal of PPCPs in the Jinsha River. The risk assessment also revealed that some PPCPs posed risks to aquatic organisms in the Jinsha River. Anthropogenic activities including human habitation and dam construction had different influence on PPCPs. PPCP distribution varied significantly across the "Hu Huanyong line", indicating human habitation significantly influenced PPCP distribution. Dam construction was insignificant in altering PPCP distribution throughout the Jinsha River. Moreover, the land use index indicated degradation level of multiple lands related to anthropogenic activities and represented the major sources of PPCPs in the Jinsha River. Most PPCPs were correlated with anthropogenic lands, for example, antibiotics, analgesics, and endocrine disrupting chemicals mainly originated from artificial surfaces, whereas other PPCPs mainly originated from cultivated lands. Together, this study indicates the disturbances of multiple anthropogenic activities on PPCP distribution and sources along the Jinsha River, which contributes to PPCP management in rural areas. • Complex sources and distribution of PPCPs were studied along large-scale rural river. • PPCPs were ubiquitous but present at relative low levels in the Jinsha River. • Due to human habitation, PPCP distribution varied across the "Hu Huanyong" line. • Land use index reflected major PPCP sources in less urbanized area. • This study has implications for the PPCP management in rural areas worldwide. [ABSTRACT FROM AUTHOR]

• Covalent functionalization of 2D 2H-MoS 2 leads to the slight decrease in bandgap. • Solvent intercalation can cause obvious decrease in bandgap of 2D 2H-MoS 2. • Intercalation effect is an important factor affecting electrocatalytic activity. Liquid phase exfoliation (LPE) is a promising method for synthesizing two-dimensional (2D) 2H-MoS 2 due to the balance obtained in the resulting yield and quality. Improvements in the electrocatalytic activity of 2D 2H-MoS 2 are typically attributed to an increased number of active sites at the plane edges. However, the conclusion need be carefully redefined in the case of LPE, because the covalent surface modification and solvent intercalation between layers can affect the electrocatalytic activity as well. In this study, bulk 2H-MoS 2 was exfoliated in three typical solvents, including N, N-dimethyl formamide (DMF), formamide, and 1-methyl-2-pyrrolidinone (NMP), to synthesize 2H-MoS 2 nanosheets. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectrum were used to confirm the possibility of surface and interface functionalization of the 2H-MoS 2 nanosheets. Further, the effects on the electrocatalytic activity of 2H-MoS 2 nanosheets were investigated mainly by density functional theory periodic calculations based on the analysis of electronic energy band structures. The results have demonstrated that 2H-MoS 2 nanosheets prepared in formamide exhibit smaller average size and thickness, and higher electrocatalytic activity. The surface functionalization of the 2H-MoS 2 nanosheets is indeed generated by Mo-N covalent bonds due to the presence of S vacancies. Such covalent functionalization leads to a slight decrease of energy band gap with 0.03 eV in a (3 × 3 × 1) 2H-MoS 2 supercell. In contrast, the interface functionalization formed by the intercalation of solvent molecules (e.g., formamide) between layers can cause a remarkable decrease in the band gap of (1 × 1 × 2) 2H-MoS 2 , the phase transition from semiconductor to semimetal, higher carrier mobility, and smaller effective mass (m e = 0.052 m 0). [ABSTRACT FROM AUTHOR]

Abstract Continuous exposure to pharmaceuticals and personal care products (PPCPs) is a critical concern given potential toxicity impacts on aquatic environments and human health, although concentrations of PPCPs in the environment are low. While several studies have focused on the fate and toxicity of organic micropollutants in wastewater, the environmental impacts of life cycle assessment induced by these organic micropollutants in advanced wastewater treatment processes are still unknown. To address this need, an environmental evaluation of three representative advanced wastewater treatment processes (ozonation, granular activated carbon adsorption and reverse osmosis) involving PPCPs removal was conducted using life cycle assessment and USEtox model in this study. Although a large amount of PPCPs can be eliminated during conventional waste highest characterization factors for freshwater toxicity, while 17α-ethinylestradiol, sertraline, and 17β-estradiol had the highest human toxicity characterization factors. From the perspective of LCA, reverse osmosis appeared to have the greatest environmental burden due to the high energy and material consumption during the treatment process. After involving 126 PPCPs in life cycle inventory, the ecotoxicity impact results were increased significantly in three advanced wastewater treatment processes. The contribution of effluent was improved in toxicity impact category, accounting more than 25% for the three processes. The effluent (including PPCPs) as the key factor was next only to electricity and chemicals in eutrophication, ecotoxicity and human toxicity impacts category particularly. Therefore, PPCPs should not be ignored in life cycle assessment of advanced wastewater treatment processes, although they are not typically monitored in wastewater. These results are valuable for conducting a comprehensive environmental evaluation of advanced wastewater treatment processes considering micro-pollutants removal. The identified PPCPs with high freshwater and human toxicity can be considered as the priority control index of organic micropollutants for wastewater treatment plants. Graphical abstract Image 1 Highlights • New characterization factors of 60 PPCPs were estimated. • The impact scores of 126 PPCPs were incorporated into the life cycle assessment. • 126 PPCPs were involved in life cycle inventory. • PPCPs contribute higher freshwater toxicity impacts than human toxicity impacts. • The 126 PPCPs account for 2.6% of total ecotoxicological results. [ABSTRACT FROM AUTHOR]

Abstract Blackening and odorization of heavily polluted rivers has become a vital aquatic environmental problem in developing countries and has threatened river ecosystems. Monitoring the contamination and functional degradation conditions is important for bioremediation of river ecosystems. In this study, the diversity, composition, co-occurrence pattern, and function of bacterial communities collected from a heavily polluted urban river sediment were investigated using 16S rRNA amplicon sequencing analysis. The degree of pollution in the river was divided into three levels, and the clustering result based on the relative abundance of bacterial communities was consistent with the pollution levels in the river. The community assembly analysis further demonstrated that bacterial community assembly was mainly driven by environmental selection (95.84%) in Jinchuan River. Composition of bacterial communities were clearly different at different pollution level sites, although no apparent changes in alpha diversity were observed. The complexity of the bacterial co-occurrence network decreased with aggravation of the pollution level, as indicated by topological features, suggesting that the interactions among bacterial communities were weakened. A phylogenetic Investigation of Communities by Reconstruction of Unobserved States analysis predicted that the relative abundance of functional genes was negatively correlated with pollution levels, and those related to energy metabolism as well as xenobiotic biodegradation and metabolism decreased significantly. These results provide an ecological reference for monitoring and bioremediation of aquatic ecosystems. Graphical abstract Image 1 Highlights • Bacterial community assembly was mainly driven by environmental selection in Jinchuan River. •Bacterial communities at different pollution levels showed different compositions clearly. •The complexity of bacterial co-occurrence network reduced with the aggravation of pollution levels. •Relative abundances of functional profiles were negatively correlated with the pollution levels. [ABSTRACT FROM AUTHOR]

Abstract Black-odor phenomenon in highly urbanized river is increasingly recognized as a global ecological risk. Biotransformation associated with sulfur cycle is a major contributor to the blank-odor phenomenon. The vertical geochemical gradient in black-odor rivers is likely to alter microbial community assemblages and functions in the sulfur cycle. However, the interactions between geochemical gradients and microbial communities, as well as the changes in the process of sulfur biotransformation under different environmental conditions remain largely unknown. The vertical community assembly patterns and the impacts of microbial communities and genes on the biotransformation in the sulfur cycle were revealed in our study for the first time in a typical urban black-odor river, Jinchuan River, in China. Vertical beta-diversity patterns of microbial communities mainly resulted from species replacement that was largely driven by spatial turnover (β SIM = 0.43) but also influenced by nestedness (β NES = 0.08). MiSeq sequencing and GeoChip 5.0 microarray chip approaches were applied and identify 41 bacterial genera, 8 archaeal genera, and 26 genes involved in the sulfur cycle in Jinchuan River. The vertical beta-diversity patterns of microbial profile mainly resulted from species replacement. Those sulfur-related bacterial and archaeal genera, accounting for 23.15% and 42.65% of the total bacteria and archaea respectively in analysed samples, were mainly responsible for sulfur reduction. According to redundancy analysis, oxidation-reduction potential (r = −0.8662, P < 0.05), S2− concentration (r = −0.6288, P < 0.05), and total nitrogen concentration (r = −0.6782, P < 0.05) were identified as factors that significantly affect sulfur-related microbial communities. The highest reaction potential was detected in the dissimilated sulfate reduction action and experienced an increase with depth increasing in the river system. The results indicated that the sulfur biotransformation in a deeper layer in river sediment could make more contribution to the black-odor phenomenon in urban rivers. Graphical abstract Image 1 Highlights • Vertical structured microbial communities in an urban river were detected. • Functions of microbial community on sulfur biotransformation were detected. • Remarkable micro-scale differentiations were found in different depths of rivers. • Vertical microbial beta-diversity patterns were largely driven by spatial turnover. • Sulfur biotransformation in deeper sediment contributes more to river pollution. [ABSTRACT FROM AUTHOR]

With the increasing human disturbance to urban rivers, the extinction and biodiversity losses of some macroorganism species decreased the accuracy of bioassessment. In this study, a novel index of biotic integrity based on bacteria (Ba-IBI) was first developed for Qinhuai River in Nanjing city, China. Thirty-two biofilm samples were collected along the river bank and the bacterial communities were identified by high-throughput sequencing. By the range, responsive, and redundancy tests, four core metrics were selected from the dataset of 78 candidate metrics, including Pielou's evenness index, proportion of Paenibacillus , proportion of OTUs tolerant to organic pollution and proportion of Nitrosomonas. The results showed that the Ba-IBI was able to effectively discriminate different impaired site groups, and had a good correlation with the index of water quality (r = 0.79, p < 0.01) and the qualitative habitat evaluation index (r = 0.51, p < 0.01). Moreover, the Ba-IBI was negatively correlated with the number of population within a 1 km buffer (r = −0.71, p < 0.01). Application of the index showed that most of the sites were in the poor or bad class in the river. Our study revealed that the Ba-IBI is an effective and reliable approach for assessing the ecological status of Qinhuai River basin, which can complement the existing ecological assessment approaches for urban rivers. Meanwhile, repeted surveys and field validations are still needed to further improve the applicability of the index in future studies. [ABSTRACT FROM AUTHOR]

The effects of CeO 2 nanoparticles (CeO 2 NPs) on a sequencing batch biofilm reactor (SBBR) with established biological phosphorus (P) removal were investigated from the processes of anaerobic P release and aerobic P uptake. At low concentration (0.1 mg/L), no significant impact was observed on total phosphorus (TP) removal after operating for 8 h. However, at a concentration of 20 mg/L, TP removal efficiency decreased from 83.68% to 55.88% and 16.76% when the CeO 2 NPs were added at the beginning of the anaerobic and aerobic periods, respectively. Further studies illustrated that the inhibition of the specific P release rate was caused by the reversible states of Ce 3+ and Ce 4+ , which inhibited the activity of exo polyphosphatase (PPX) and transformation of poly-β-hydoxyalkanoates (PHA) and glycogen, as well as the uptake of volatile fatty acids (VFAs). The decrease in the specific P uptake rate was mainly attributed to the significantly suppressed energy generation and decreased abundance of Burkholderia caused by excess reactive oxygen species. The removal of chemical oxygen demand (COD) was not influenced by CeO 2 NPs under aerobic conditions, due to the increased abundance of Acetobacter and Acidocella after exposure. The inhibitory effects of CeO 2 NPs with molecular oxygen were reduced after anaerobic exposure due to the enhanced particle size and the presence of Ce 3+ . [ABSTRACT FROM AUTHOR]

Water management strategies play an important role in water shortage alleviation. This study evaluates the cost and water ecosystem benefit of 14 water management strategies in Beijing in the future scenarios for 2020 and 2035. In addition, optimal implements of abatement strategies are obtained within the context of legislated targets, with the consideration of interaction among strategies. The result shows that Beijing can meet its commitments for total water use and pollution control by the water management strategies implementation in both 2020 and 2035. For 14 water management strategies analyzed in this study, 5 options with negative abatement cost value achieve 12.2–24.1% of the total water ecosystem benefit in 2020 and 2035. Wastewater reclamation is the most efficient strategy in water ecosystem impact (WEI) reduction, which contributes 38.4% of the total WEI reduction with an abatement cost of 1.6 Yuan/m3 H 2 O -eq. However, the sequence of optimal strategy implementation rate is not in accordance with the abatement cost of the strategies. The most cost-effective option is the water-efficient shower head, while the highest implementation rate is found for promotion of production technologies. A comparison between water management optimization with and without the consideration of interactions among strategies shows that taking the interaction among strategies into account imposes almost no influence on the total WEI reduction. But it has impacts on optimal implementation rate of each water management option and the cost estimation (+10.8%) of water management implementation. Such a systematic analysis of water management strategies provides general recommendations on sustainable water resource management in water scarce regions. Image 1 • Cost and water ecosystem benefit of 14 water strategies were evaluated. • Water management options were optimized within the legislated targets. • Beijing can meet its commitments for total water use and pollutants discharge. • Sequence of strategy implement rate is not in accordance with its abatement cost. • Interaction among strategies has almost no impact on optimal WEI reduction. [ABSTRACT FROM AUTHOR]

The confluence area of river networks is a hot spot for pollutant removal. As an essential part of the river ecosystem, sediment bacterial communities played a crucial role in the removal of pollutants. However, how the potential of sediment bacterial communities can be enhanced toward the removal of pollutants remains unclear. Therefore, this study provides a new approach for the identification of key environmental factors that enhance the pollutant removal potential at a river confluence, integrating the bacteria-based index of biotic integrity (Ba-IBI), path model, support vector regression (SVR) model, and sensitivity analysis. The developed Ba-IBI could quantitatively evaluate the differences of both structure and function of bacterial communities before and after the confluence, with a range from 1.52 to 2.78. The flow regime, which was represented by the Froude number, exerted an indirect effect on Ba-IBI mediated through water nutrients and sediment nutrients according to path model results. Sediment nutrients and water nutrients were considered as the main environmental factors that directly affected sediment bacterial communities. A function that could predict the response of sediment bacterial communities to environmental factors in the best possible way was found through SVR modeling, with R2 = 0.8357. The results of the sensitivity analysis indicated that the total phosphorus in water and ammonia nitrogen in sediments were key environmental factors for enhancing the pollutant removal potential at the river confluence. The established approach aids the improvement of the bioremediation potential of river confluence area, and might provide a theoretical basis for watershed restoration. Image 1 • A new approach for enhancing pollutant removal potential was established. • Bacteria-based index of biotic integrity (Ba-IBI) could distinguish communities. • Flow regime affected Ba-IBI mediated through water and sediment nutrients. • The TP in water and NH 4 +-N in sediments were key environmental factors. [ABSTRACT FROM AUTHOR]

Excessive nitrogen (N) input is one of the most important causative factors of lake eutrophication, which has aroused increasing public attention in past decades. Estrogen contamination is also an increasing environmental problem in aquatic systems around the world. Although both substances usually co-exist in aquatic ecosystems, many researches have only investigated the influences of either N or estrogen individually on sediment bacterial community and nitrous oxide (N 2 O) emission. Knowledge regarding the combined effects of N and estrogen is still very limited. In this study, a 30-day laboratory incubation experiment was performed to examine the impacts of different N sources (ammonium and nitrate) combined with 17β-estradiol (E2) on sediment bacterial community. High-throughput 16S rRNA gene sequencing technique was used and N 2 O emission was measured. The results revealed that the relative abundances of Proteobacteria and Bacteroidetes were higher in nitrate treatment than ammonium treatment. Compared to N treatments, N and E2 combined treatments showed higher relative abundances of Proteobacteria, Bacteroidetes, and Firmicutes, but lower relative abundances of Chloroflexi, Acidobacteria, and Actinobacteria over entire incubation period. At the genus level, the relative abundances of genera Flavobacterium , Pseudomonas , Arenimonas , Novosphingobium , Massilia , Aquabacterium , and Bacillus were enhanced by N treatments and especially N and E2 combined treatments, compared to sediment without addition of N and E2. However, the relative abundances of Sporacetigenium , Gaiella , Desulfatiglans , Nitrospira , and Haliangium were decreased in N treatments. Apart from the changes in bacterial community structure, N 2 O emission was also influenced by different treatments. Nitrate exerted a more significant positive effect on N 2 O emission than ammonium, and the cumulative emission of N 2 O was highest in nitrate and E2 combined treatment. Very low abundances of ammonia monooxygenase (amoA) gene and hydroxylamine oxidase (hao) gene were observed in sediments compared to other genes involved in N cycles (such as nitrate reductase (narG and napA) genes, nitrite reductase (nirB , nirK , and nrfA) genes, and nitric oxide reductase (norB) gene), implying that denitrification rather than nitrification played an important role in sediments. The abundances of napA , nirK , and norB were higher in N and E2 combined treatments, indicating that E2 might provide a carbon source for denitrifiers. Moreover, decrease in the abundance of nitrous oxide reductase (nosZ) gene during the denitrifying process in N and E2 combined treatment might be an important reason for increases of N 2 O emission. These results indicated that alterations of the bacterial community structure due to the co-existence of N and E2 could also change the abundances of genes involved in N cycle. Image 1 • Bacteria varied greatly in their responses to N and E2 addition in sediments. • Several genera related to N cycle showed higher relative abundances in N and E2 combined treatments. • N 2 O flux was highest in nitrate and E2 combined treatment, while lowest in ammonium treatment. • E2 addition increased the abundances of denitrifying genes in sediments. • Decline of nosZ abundance in N and E2 combined treatments might lead to higher N 2 O emission. [ABSTRACT FROM AUTHOR]