Triclosan disturbs nitrogen removal in constructed wetlands: Responses of microbial structure and functions.

This study investigated the influence of wetland types (vertical and tidal flow constructed wetlands [CWs] [VFCW and TFCW, respectively]) and concentrations of triclosan (TCS) on the removal of pollutants (TCS and nitrogen) and microbial characteristics. The efficiency of TCS removal was significantly higher with 5 µg/L TCS (Phase B) than with 30 µg/L (Phase C) in the two CWs. The efficiencies of removal of NH4+-N and NO3--N were significantly inhibited in Phase C. Compared with the VFCW, the TFCW removed more NH4+-N at the same concentration of TCS, whereas less NO3--N was removed, and it even accumulated. Saccharimondales, an important functional genus with the highest abundance and more node connections with other genera, had a sharp decrease in relative abundance as the increasing concentrations of TCS of the two CWs conformed with its relative abundance and significantly negatively correlated with the concentration of TCS. Differentiated Roseobacter_Clade_CHAB-I-5_Lineage and Sphaerotilus were enriched in the VFCW and TFCW, respectively. The abundance of enzymes that catalyzed nitritation was significantly inhibited by TCS, whereas nitrate reductase (EC 1.7.99.4) catalyzed both denitrification and dissimilatory nitrate reduction to ammonium (DNRA), and nitrite reductase (NADH) (EC 1.7.1.15) that catalyzed DNRA comprised a larger proportion in the two CWs. Simultaneously, the abundances of two enzymes were higher in the TFCW than in the VFCW. The network analysis indicated that the main genera were promoted more by TCS in the VFCW, while inhibited in the TFCW. Moreover, the concentrations of nitrogen (NH4+-N, NO3--N, and TN) significantly positively correlated with TCS-resistant bacteria, and negatively correlated with most nitrogen-transforming bacteria with species that varied between the VFCW and TFCW. The results of this study provide a reference for the molecular biological mechanism of the simultaneous removal of nitrogen and TCS in the CWs.

The diversity and biogeography of bacterial communities in lake sediments across different climate zones.

Bacteria are diverse and play important roles in biogeochemical cycling of aquatic ecosystems, but the global distribution patterns of bacterial communities in lake sediments across different climate zones are still obscure. Here we integrated the high-throughput sequencing data of 750 sediment samples from published literature to investigate the distribution of bacterial communities in different climate zones and the potential driving mechanisms. The obtained results indicated that the diversity and richness of bacterial community were notably higher in temperate and cold zones than those in other climate zones. In addition, the bacterial community composition varied significantly in different climate zones, which further led to changes in bacterial functional groups. Specifically, the relative abundance of nitrogen cycling functional groups in polar zones was notably higher compared to other climate zones. Regression analysis revealed that climate (mean annual precipitation, MAP; and mean annual temperature, MAT), vegetation, and geography together determined the diversity pattern of sediment bacterial community on a global scale. The results of partial least squares path modeling further demonstrated that climate was the most significant factor affecting the composition and diversity of bacterial communities, and MAP was the most important climate factor affecting the composition of bacteria community (R2 = 0.443, P < 0.001). It is worth noting that a strong positive correlation was observed between the abundance of the dominant bacterial group uncultured_f_Anaerolineaceae and the normalized difference vegetation index (NDVI; P < 0.001), suggesting that vegetation could affect bacterial community diversity by influencing dominant bacterial taxa. This study enhances our understanding of the global diversity patterns and biogeography of sediment bacteria.

Terrestrial sources regulate the endogenous phosphorus load in Taihu Lake, China after exogenous controls: Evidence from a representative lake watershed.

Identifying phosphorus (P) sources and contributions from terrestrial sources is important for clean water and eutrophication management in lake watersheds. However, this remains challenging owing to the high complexity of P transport processes. The concentrations of different P fractions in the soils and sediments from Taihu Lake, a representative freshwater lake watershed, were obtained using sequential extraction procedure. The dissolved phosphate (PO4-P) and alkaline phosphatase activity (APA) in the lake's water were also surveyed. The results showed that different P pools in the soil and sediments displayed different ranges. Higher concentrations of P fractions were measured in the solid soils and sediments from the northern and western regions of the lake watershed, indicating a larger input of P from exogenous sources, including agriculture runoff and industrial effluent from the river. Generally, higher Fe-P and Ca-P concentrations of up to 399.5 and 481.4 mg/kg were detected in soils and lake sediments, respectively. Similarly, the lake's water had higher concentrations of PO4-P and APA in the northern region. A significant positive correlation was found between Fe-P in the soil and PO4-P concentrations in the water. Statistical analysis indicated that appropriately 68.75% P was retained in the sediment from terrigenous sources, and 31.25% P experienced dissolution and shifted to the solution phase in the water-sediment ecosystems. The dissolution and release in Fe-P in the soils were responsible for the increase of Ca-P in the sediment after the afflux of soils into the lake. These findings suggest that soil runoff predominantly controls P occurrence in lake sediments as an exogenous source. Generally, the strategy of reducing terrestrial inputs from agricultural soil discharge is still an important step in P management at the catchment scale of lakes.

How do inundation provoke the release of phosphorus in soil-originated sediment due to nitrogen reduction after reclaiming lake from polder.

Different N and P fractions in microcosm incubation experiment was measured using high-resolution in-situ Peeper and DGT techniques combining with sequential extraction procedure. The results showed the synchronous desorption and release of PO43-, S2- and Fe2+ from the solid soil-originated sediment. This trend indicated that the significant reduction of Fe-P and SO42- occurred in the pore water during the inundation. The concentrations of PO43- in the overlying water and pore water increased to more than 0.1 and 0.2 mg/L at the beginning of the incubation experiment. Decreased NO3-concentrations from more than 1.5 mg/L to less than 0.5 mg/L combining with increasing NH4+ concentrations from less than 1 mg/L to more than 5 mg/L suggested the remarkable NO3- reduction via dissimilatory nitrate reduction to ammonia (DNRA) pathway over time. High NH4+ concentrations in the pore water aggravated the release of Fe2+ through reduction of Fe(III)-P as electric acceptors under anaerobic conditions. This process further stimulated the remarkable releasing of labile PO43- from the solid phase to the solution and potential diffusion into overlying water. Additionally, high S2- concentration at deeper layer indicated the reduction and releasing of S2- from oxidation states, which can stimulated the NO3- reduction and the accumulation of NH4+ in the pore water. This process can also provoke the reduction of Fe-P as electric acceptors following the release of labile PO43- into pore water. Generally, inundation potentially facilitate the desorption of labile P and attention should be paid during the reclaiming lake from polder.

Heavy Metals Present in the Soils from Extremely Large Opencast Iron Mine Pit.

The mining areas have faced severe pollution by caustic metals. In this study, heavy metals (Cu, Zn, Cr, Cd, Pb and Ni) in the soil of an extremely large iron mine pit from Ningwu-Luohe metallogenic belt, one of the seven iron ore areas in China was characterized. SiO2 was predominant soil mineral composition as 57.0 ± 1.3 %, followed by considerable Al2O3 (23.1 ± 2.5 %) and Fe2O3 (8.58 ± 1.2 %). Cu, Zn, Cr, Cd, Pb and Ni had the range of 7.62-237, 97.8-313, 1.73-43.8, 0.119-0.512, 5.13-44.7 and 7.87-23.9 mg/kg, respectively, wherein, Cu, Zn, Cr and Pb were likely to have relatively low concentration in the soil from the boom of mining pit. Comparatively, both Cu and Zn arose at the level of 1-fold higher than that of local background values, indicating that the soil from mining pit had been subjected to Cu and Zn accumulation. BCR (European Communities Bureau of Reference) sequential extraction analysis showed that these metals mainly existed in residual fraction, with averaged percentages of 42.0 ± 18 %, 70.3 ± 8.1 %, 76.6 ± 18 %, 30.2 ± 14 %, 52.5 ± 11 % and 61.0 ± 9.7 % for Cu, Zn, Cr, Cd, Pb and Ni, respectively. Geo-accumulation index indicates that the soil was moderately contaminated by Cu, practically uncontaminated or uncontaminated to moderately contaminated by Zn, while practically uncontaminated by Cr, Cd, Pb and Ni. There were just significant relationships between Zn and Cd and between Cd and Pb, indicating that Cd in the soil investigated possibly had at least two sources and for most of the elements the sources were different. The effects of pit depth and major soil composition on the distribution of trace metals varied depending on the element itself and its chemical forms.

Effects of reductive inorganics and NOM on the formation of chlorite in the chlorine dioxide disinfection of drinking water.

Chlorine dioxide (ClO2) disinfection usually does not produce halogenated disinfection by-products, but the formation of the inorganic by-product chlorite (ClO2-) is a serious consideration. In this study, the ClO2- formation rule in the ClO2 disinfection of drinking water was investigated in the presence of three representative reductive inorganics and four natural organic matters (NOMs), respectively. Fe2+ and S2- mainly reduced ClO2 to ClO2- at low concentrations. When ClO2 was consumed, the ClO2- would be further reduced by Fe2+ and S2-, leading to the decrease of ClO2-. The reaction efficiency of Mn2+ with ClO2 was lower than that of Fe2+ and S2-. It might be the case that MnO2 generated by the reaction between Mn2+ and ClO2 had adsorption and catalytic oxidation on Mn2+. However, Mn2+ would not reduce ClO2-. Among the four NOMs, humic acid and fulvic acid reacted with ClO2 actively, followed by bovine serum albumin, while sodium alginate had almost no reaction with ClO2. The maximum ClO2- yields of reductive inorganics (70%) was higher than that of NOM (around 60%). The lower the concentration of reductive substances, the more ClO2- could be produced by per unit concentration of reductive substances. The results of the actual water samples showed that both reductive inorganics and NOM played an important role in the formation of ClO2- in disinfection.

Algal Accumulation Decreases Sediment Nitrogen Removal by Uncoupling Nitrification-Denitrification in Shallow Eutrophic Lakes.

In eutrophic lakes, the decay of settled algal biomass generates organic carbon and consumes oxygen, favoring sediment nitrogen loss via denitrification. However, persistent winds can cause algae to accumulate into dense mats, with uncertain impacts on sediment nitrogen removal. In this study, we investigated the effects of algal accumulation on sediment nitrogen removal in a shallow and eutrophic Chinese lake, Taihu. We found that experimental treatments of increased algal accumulation were associated with decreased sediment nitrogen losses, indicating the potential for a break in coupled nitrification-denitrification. Likewise, field measurements indicated similar decreases in sediment nitrogen losses when algal accumulation occurred. It is possibly caused by the decay of excess algal biomass, which likely depleted dissolved oxygen, and could have inhibited nitrification and thereby denitrification in sediments. We estimate that if such algal accumulations occurred over 20% or 10% of lake area in Taihu, sediment nitrogen removal rates decreased from 835.6 to 167.2 and 77.2 µmol N m-2h-1, respectively, during algal accumulation period. While nitrogen removal may recover later, the apparent nitrogen removal decrease may create a window for algal proliferation and intensification. This study advances our knowledge on the impacts of algal blooms on nitrogen removal in shallow eutrophic lakes.

Characteristics of particle size distribution and related contaminants of highway-deposited sediment, Maanshan City, China.

Road-deposited sediment (RDS) has been identified as both the source and sink of various pollutants. In this study, the highway-deposited sediment (HDS) in Spring, Summer, Autumn and Winter was characterized. On average, the mass proportions of particles with the size of 830-4750 µm, 500-830 µm, 250-500 µm, 150-250 µm, 63-150 µm and < 63 µm were 23.6 ± 8.6%, 16.9 ± 3.4%, 28.4 ± 3.5%, 10.0 ± 4.3%, 15.7 ± 5.8% and 5.3 ± 2.0%, respectively, wherein the HDS of 63-830 µm accounted for 71% of the total mass load. It was observed that the particle size distribution of HDS could be described using the gamma distribution function based on gravimetric and cumulative basis (R2 (determination coefficient) = 0.9960-0.9995). The bulk pollutant contents of HDS showed seasonal variation with the mean of COD (chemical oxygen demand), nitrogen, phosphorus, Zn (zinc), Pb (lead) and Cd (cadmium) as 57 g/kg, 839 mg/kg, 97 mg/kg, 627 mg/kg, 110 mg/kg and 1.00 mg/kg and the highest COD of 83 g/kg in Autumn, nitrogen 1164 mg/kg Autumn, phosphorus 133 mg/kg Winter, Zn 801 mg/kg Summer, Pb 133 mg/kg Spring and the highest Cd of 1.36 mg/kg in Summer, respectively. The contents of Zn, Pb and Cd in HDS were significantly above their local soil background values. Moreover, the size fractional pollutant contents overall increased as particles' size increased. Averagely, 40-52% pollutant loads were associated with the particles < 250 µm, which can be moved easily by runoff. This study suggests that the behaviors of HDS different from city RDS should be considered as nonpoint source pollution control is performed.

Anchored Cobalt Nanoparticles on Layered Perovskites for Rapid Peroxymonosulfate Activation in Antibiotic Degradation.

In the Fenton-like reaction, revealing the dynamic evolution of the active sites is crucial to achieve the activity improvement and stability of the catalyst. This study reports a perovskite oxide in which atomic (Co0) in situ embedded exsolution occurs during the high-temperature phase transition. This unique anchoring strategy significantly improves the Co3+/Co2+ cycling efficiency at the interface and inhibits metal leaching during peroxymonosulfate (PMS) activation. The Co@L-PBMC catalyst exhibits superior PMS activation ability and could achieve 99% degradation of tetracycline within 5 min. The combination of experimental characterization and density functional theory (DFT) calculations elucidates that the electron-deficient oxygen vacancy accepts an electron from the Co 3d-orbital, resulting in a significant electron delocalization of the Co site, thereby facilitating the adsorption of the *HSO5/*OH intermediate onto the "metal-VO bridge" structure. This work provides insights into the PMS activation mechanism at the atomic level, which will guide the rational design of next-generation catalysts for environmental remediation.

Refractory degradable dissolved organic matter (R-DOM) driving nitrogen removal by the electric field coupled iron­carbon biofilter (E-ICBF): Performance and microbial mechanisms.

Researches on the advanced nitrogen (N) removal of municipal tailwater always overlooked the value of refractory degradable dissolved organic matter (R-DOM). In this study, a novel electric field coupled iron­carbon biofilter (E-ICBF) was utilized to explore the performance and microbial changes with polyethylene glycol (PEG) as the representative R-DOM. Results demonstrated that the removal efficiencies of E-ICBF for nitrate nitrogen (NO3--N), ammonia nitrogen (NH4+-N), and total nitrogen (TN) improved by 28.76 %, 12.96 %, and 28.45 %, compared to quartz sand biofilter (SBF). Moreover, removal efficiencies of NO3--N and TN in E-ICBF with R-DOM went up by 12.11 % and 14.02 % compared to methanol. Additionally, both PEG and the electric field reduced the microbial richness and diversity. However, PEG promoted the increase of denitrifying bacteria abundance including unclassified_f_Comamonadaceae, Thauera, and unclassified_f_Gallionellaceae. The electric field improved the abundances of genes related to N removal (hao, nasC, nasA, nifH, nifD, nifK) and PEG further enhanced the effect. The abundances of key enzymes [EC:1.7.5.1], [EC:1.7.2.1], [EC:1.7.2.4], and [EC:1.7.2.5] decreased due to the addition of PEG and the electric field mitigated the negative influence. Additionally, the electric field changed relationships between microorganisms and pollutant removal, and improved interspecific relationships between denitrifying bacterial genera and other genera in E-ICBF.

Deciphering the anammox microbial community succession with humic acid exposure to optimize large anammox granules for robust nitrogen removal.

The robustness of the anaerobic ammonia oxidation (anammox) process in treating wastewater with high concentrations of humic acids (HAs), including landfill leachate and sludge anaerobic digestion liquid, has been paid great attention. This study revealed that the anammox sludge granule size of 1.0-2.0 mm could be robust under the HA exposure with high concentrations. The total nitrogen removal efficiency (NRE) was 96.2% at the HA concentration of 20-100 mg/L, while the NRE was 88.5% at the HA concentration of 500 mg/L, with reduced by 7.7%. The increased extracellular polymeric substances (EPS) content which was stimulated by the HA exposure favored the formation of large granules (1.0-2.0 mm) by enveloping medium and micro granules (0.2-1.0 mm). The abundance of anammox bacteria Candidatus Brocadia was found to be higher (14.2%) in large anammox granules sized 1.0-2.0 mm, suggesting a potentially high anammox activity. However, the abundance of denitrifiers Denitratisoma increased by 4.3% in ultra-large anammox granules sized >2.0 mm, which could be attributed to the high EPS content for heterotrophic denitrifiers metabolism as organic matter. The feedback mechanism of the anammox community for maintaining the ecological function under the HA exposure resulted in a closely related microbial community, with positive and negative correlations in the ecological network increased by 64.3%. This study revealed that the HA exposure of the anammox system resulted in the anammox granules of 1.0-2.0 mm size being the dominant granules with robust nitrogen removal, providing significant guidance for the optimization of anammox granules for an efficient treatment of HA-containing wastewater in anammox applications.

Regime difference between macrophyte and Cyanophyta dominance regulate microbial carbon sequestration mode in lake sediments.

Different nutrient load in the lake ecosystems trigger the regime difference and change of predominant biotype. The regulation of carbon (C) sequestration mode in the lacustrine sediments in response to this process need prudent clarification. Fluorescence measurements and high-throughput sequencing for functional genes cbbL and cbbM encoding C-fixing bacteria genus were executed for sediments from two representative regimes dominated by macrophyte and Cyanophyta, respectively. The results showed that humic-like and fulvic-acid like materials dominated the dissolved organic matter (DOM) from the algae and macrophyte-dominated lake regions, respectively. Microbial assimilation played critical influence on C fixation into the sediments in both of the two regimes. However, higher diversity was detected in macrophyte-dominated regime compared to that in Cyanophyta-dominated regime, suggesting that moderate nutrient levels facilitated the species richness of bacteria encoding functional genes concerning C fixation. Bacterial species and diversities varied between two regimes including predominant and rare taxa, suggesting that community structure alteration due to regime difference triggered the regulation the C sequestration mode and stability. Predominant genera manipulated the abundance of C-fixing bacteria genes in response to the regulation of nutrient levels. Noted that rare genera also responded to the regime difference and played key role in C sequestration into lacustrine sediments. Our results suggest that more abundant macrophyte-dominated regime facilitated the C sequestration in the lake ecosystems for atmospheric C reduction.

Metabolism and distribution of two major constituents of 'Xing-Nao-Jing Injection'-germacrone and curdione in rats.

Germacrone and curdione are germacrane-type sesquiterpenoids that are widely distributed and have extensive pharmacological activities; they are the main constituents of 'Xing-Nao-Jing Injection' (XNJ). Studies on the metabolic features of germacrane-type sesquiterpenoids are limited. In this study, the metabolites of germacrone and curdione were characterized by UHPLC-Q-Exactive Oribitrap mass spectrometry after they were orally administered to rats. In total, 60 and 76 metabolites were found and preliminarily identified in rats administered germacrone and curdione, respectively, among which at least 123 potential new compounds were included. New metabolic reactions of germacrane-type sesquiterpenoids were identified, which included oxidation (+4 O and +5 O), ethylation, methyl-sulfinylation, vitamin C conjugation, and cysteine conjugation reactions. Among the 136 metabolites (including 113 oxidation metabolites, two glucuronidation, two methylation, nine methyl-sulfinylation, three ethylation, six cysteine conjugation, and one Vitamin C conjugation metabolites), 32 metabolites were detected in nine organs, and the stomach, intestine, liver, kidneys, and small intestine were the main organs for the distribution of these metabolites. All 136 metabolites were detected in urine and 64 of them were found in feces. The results of this study not only contribute to research on in vivo processes related to germacrane-type sesquiterpenoids but also provide a strong foundation for a better understanding of in vivo processes and the effective forms of germacrone, curdione, and XNJ.

Performance evaluation and modeling of synthetic-fiber barrier in the treatment of turbid water.

A synthetic-fiber barrier for the removal of turbidity in water was developed and tested using a laboratory scale channel. The effects of hydraulics (flow rate and exchange rate); density current caused by temperature and turbidity difference; barrier conditions (thickness, number and shape); and particle size were analyzed. The experimental results indicated that removal efficiency was positively related to barrier thickness and number, was inversely related to the strength of the density current, and was also negatively affected by the flow rate and exchange rate. A wedged barrier was found to work better than a rectangular one when the same amount of fiber was used. Based on the experimental work, empirical models for the removal efficiency and barrier design were established using dimensionless groups. The modeling results indicated that the predicted values were consistent with the experimental work and the increases and decreases in the performance were suitably simulated.

Model development and application design of fiber mat used for turbid runoff treatment.

Performance of a synthetic-fibre mat was investigated for the treatment of high-turbidity runoff. The impact of different operating parameters, such as hydraulics (flow rate and exchange rate), density current due to temperature and turbidity differences, mat conditions (thickness and number) and particle size were studied. The experimental results showed that increasing the mat thickness and number enhanced turbidity removal. The density current showed significant inverse effect on mat performance. Turbidity removal decreased with the increasing flow rate and exchange rate. Particle size also indicated an influence on removal efficiency. Predictive correlations for turbidity removal efficiency and mat design were established using dimensionless groups based on the experiment. The simulation results indicated that the predicted values correlated with the experimental ones significantly. Finally, the application design process was demonstrated.

Microplastics as vectors of organic pollutants in aquatic environment: A review on mechanisms, numerical models, and influencing factors.

Microplastics (MPs), a new class of emerging pollutants, have attracted exponentially increased attention due to the adverse ecological impacts on biota, not only by themselves but also by the combined corrosive substances. However, the occurrence mechanisms, numerical models and influencing factors of MPs adsorbing organic pollutants (OPs) show a significant variation with literatures. Therefore, this review is focused on the adsorption of OPs on MPs, including mechanisms, numerical models, and influencing factors, to obtain a comprehensive understanding. Research shows that MPs with strong hydrophobicity have high adsorption capacity for hydrophobic OPs. Hydrophobic distribution and surface adsorption are considered to be the main mechanisms by which MPs adsorb OPs. The available literature suggests that the pseudo-second-order model describes the adsorption kinetics of OPs on MPs better than the pseudo-first-order model, while the choice of Freundlich or Langmuir isotherm model depends mainly on the specific environmental conditions. Moreover, the characteristics of MPs (composition, particle size, aging, etc.), the nature of OPs (concentration, polarity, hydrophilicity, etc.), the environmental conditions (temperature, salinity, pH, ionic strength, etc.), and the substances co-existing in the environment (e.g., DOM and surfactants) are all important factors affecting the adsorption behavior of MPs for OPs. Environmental conditions can also indirectly affect the adsorption of hydrophilic OPs adsorbed on MPs by causing changes in the surface properties of MPs. Based on the current knowledge, the perspective shortening the knowledge gap is also suggested.

Differential cytotoxicity to human cells in vitro of tire wear particles emitted from typical road friction patterns: The dominant role of environmental persistent free radicals.

Tire wear particles (TWPs) have been recognized as one of the major sources of microplastics (MPs), however, effects of initial properties and photochemical behavior of TWPs on cytotoxicity to human cells in vitro have not been reported. Therefore, here, three TWPs generated from typical wear of tires and pavements (i.e., rolling friction (R-TWPs) and sliding friction (S-TWPs)) and cryogenically milled tire tread (C-TWPs), respectively, and their photoaging counterparts were used to study the reasons for their differential cytotoxicity to 16HBE cells in vitro. Results showed in addition to changes of surface structure and morphology, different preparation methods could also induce formation of different concentration levels of environmental persistent free radicals (EPFRs) (from 1.24 to 3.06 × 1017 spins/g with g-factors ranging 2.00307-2.00310) on surfaces of TWPs, which contained 7.3%-65.8% of reactive EPFRs (r-EPFRs). Meanwhile, photoaging for 90 d could strengthen formation of EPFRs (from 4.03 to 4.61 × 1017 spins/g) with containing 74.7%-78.1% r-EPFRs on surfaces of TWPs and improve their g-factor indexes (ranging 2.00309-2.00313). At 100 µg mL-1 level, compared to C-TWPs, both R-TWPs and S-TWPs (whether photoaging or not) carried higher intensity EPFRs could significantly inhibit 16HBE cells proliferation activity, cause more cells oxidative stress and induce more cell apoptosis/necrosis and secretion of inflammatory factor (P < 0.05). However, regardless of how TWPs were prepared, photoaged or not, exposure at a concentration of 1 µg mL-1 appeared to be non-acute cytotoxic. Correlation analysis suggested dominant toxicity of TWPs was attributed to the formation of r-EPFRs on their surfaces, which could promote accumulation of excess reactive oxygen species in cells and the massive deposition of intracellular particles. This study provides direct evidence of TWPs cytotoxicity, and underlining the need for a better understanding of the influences of initial properties and photochemical characteristics on risk assessment of TWPs released into the environment.

Microplastics and microorganisms in sediments from stormwater drain system.

Research has already confirmed the occurrence of microplastics (MPs) in sediments of stormwater drain system (SDS). However, the microplastic pollution remains to be elucidated well in sediments, especially the spatio-temporal distribution and the impacts of MPs on microorganisms. In this study, the averaged abundance of MPs in SDS sediments was 479 ± 688 items·kg-1 for spring, 257 ± 93 items·kg-1 for summer, 306 ± 227 items·kg-1 for autumn and 652 ± 413 items·kg-1 for winter. As expected, the abundance of MPs was the lowest in summer due to runoff scouring, while the highest in winter attributed to infrequent low-intensity rainfall. The major polymers of MPs were polyethylene terephthalate and polypropylene plastics, occupying 76 % to 98 % of the total number. Fiber MPs were the most regardless of season (41 % to 58 %). MPs with size of 250-1000 µm accounted for over 50 %, which is in accordance with the previous study that MPs of <1000 µm were the major. High-throughput sequencing of analysis shows that MPs provided an ecological niche for bacterial communities different from that of SDS sediments. Actinomycetes and bacteria with chemoheterotrophic genes tended to be enriched on the surfaces of MPs. In addition, Acidobacteria and bacteria with nitrification genes would not like to present in microplastisphere. A strong positive correlation (R from 0.74 to 0.83, P < 0.01) was found between the abundance of MPs in sediments and the abundance of functional genes for denitrification and nitrogen respiration of microorganisms on the surfaces of MPs. It indicates that MPs may influence the nitrogen transformation processes in SDS sediments via the occurrence of denitrification processes on the surfaces of MPs. The abundance of MPs had no significant relationship with the various functional genes of microorganisms in the sediments (P > 0.05), which means that MPs could not profoundly influence the expression of microbial functional genes in SDS sediments.

Mitigation of ultrafiltration membrane fouling by a simulated sunlight-peroxymonosulfate system with the assistance of irradiated NOM.

Oxidation pretreatments prior to ultrafiltration are hindered by the need for energy input and sludge disposal. Herein, a simulated sunlight-induced natural organic matter (NOM) for peroxymonosulfate (PMS) activation was used as pretreatment to alleviate ultrafiltration membrane fouling caused by NOM itself in the Songhua River water. When light intensity was over 100 mW/cm2, the pretreatment removed NOM effectively, characterized with UV254, dissolved organic carbon (DOC) and maximum fluorescent intensity (Fmax), and improved filtration flux. At 200 mW/cm2 light intensity and 0.5 mM PMS, 57.5% of UV254 and 18.5% of DOC were removed, and humic-like fluorescent component was degraded by 84%-94% while ∼60% for protein-like substance. Membrane flux was increased by 94%, and reversible and irreversible fouling resistances were reduced by 62.4% and 51.9%, respectively. Both total fouling index (TFI) and hydraulic irreversible fouling index (HIFI) were moderately correlated with the DOC, whereas they prominently correlated with the UV254 and the Fmaxs of all fluorescence components, which could be served as key indicators to predict and control membrane fouling. Mathematical modeling showed that the pretreatment alleviated the fouling in the membrane pores and cake layer. The simulated sunlight-induced NOM (3NOM* and eaq¯) could activate PMS to form active species, which enabled to oxidize high molecular weight (MW) substances and mineralize low MW compounds in NOM as well as hinder their linking with inorganic cations, thereby reducing organic and inorganic membrane fouling simultaneously. This study may provide a new strategy for decentralized potable water treatment, especially in a single household or community.

Cerebral collateral circulation as an independent predictor for in-stent restenosis after carotid artery stenting.

Background: In-stent restenosis is a crucial problem after carotid artery stenting, but the exact predictors of in-stent restenosis remain unclear. We aimed to evaluate the effect of cerebral collateral circulation on in-stent restenosis after carotid artery stenting and to establish a clinical prediction model for in-stent restenosis. Methods: This retrospective case-control study enrolled 296 patients with severe carotid artery stenosis of C1 segment (≥70%) who underwent stent therapy from June 2015 to December 2018. Based on follow-up data, the patients were divided into the in-stent restenosis and no in-stent restenosis groups. The collateral circulation of the brain was graded according to the criteria of the American Society for Interventional and Therapy Neuroradiology/Society for Interventional Radiology (ASITN/SIR). Clinical data were collected, such as age, sex, traditional vascular risk factors, blood cell count, high-sensitivity C-reactive protein, uric acid, stenosis degree before stenting and residual stenosis rate, and medication after stenting. Binary logistic regression analysis was performed to identify potential predictors of in-stent restenosis, and a clinical prediction model for in-stent restenosis after carotid artery stenting was established. Results: Binary logistic regression analysis showed that poor collateral circulation was an independent predictor of in-stent restenosis (P=0.003). We also found that a 1% increase in residual stenosis rate was associated with a 9% increase in the risk of in-stent restenosis (P=0.02). Ischemic stroke history (P=0.03), family history of ischemic stroke (P<0.001), in-stent restenosis history (P<0.001), and nonstandard medication after stenting (P=0.04) were predictors of in-stent restenosis. The risk of in-stent restenosis was lowest when the residual stenosis rate was 12.5% after carotid artery stenting. Furthermore, we used some significant parameters to construct a binary logistic regression prediction model for in-stent restenosis after carotid artery stenting in the form of a nomogram. Conclusions: Collateral circulation is an independent predictor of in-stent restenosis after successful carotid artery stenting, and the residual stenosis rate tends to be below 12.5% to reduce restenosis risk. The standard medication should be strictly carried out for patients after stenting to prevent in-stent restenosis.