Antibiotic pollution in surface fresh waters: Occurrence and effects

Effect of antibiotic cocktail exposure on functional disturbance of nitrifying microbiome

The present study quantitatively determined the degree and type of functional disturbance in the nitrifying microbiome caused by exposure to a single oxytetracycline (OTC) and a two-antibiotic mixture containing OTC and sulfamethoxazole (SMX). While the single antibiotic had a pulsed disturbance on nitritation that was recoverable within three weeks, the antibiotic mixture caused a more significant pulsed disturbance on nitritation and a potential press disturbance on nitratation that was not recoverable for over five months. Bioinformatic analysis revealed significant perturbations for both canonical nitrite-oxidizing (Nitrospira defluvii) and potential complete ammonium-oxidizing (Ca. Nitrospira nitrificans) populations that were strongly associated with the press perturbation on nitratation. In addition to this functional disturbance, the antibiotic mixture reduced the biosorption of OTC and altered its biotransformation pathways, resulting in different transformation products compared with those produced when OTC was treated as a single antibiotic. Collectively, this work elucidated how the antibiotic mixture can affect the degree, type, and duration of the functional disturbance on nitrifying microbiome and offer new insights into the environmental consequences of antibiotic residues (e.g., their fate, transformation, and ecotoxicity) when present as an antibiotic mixture rather than single antibiotics.

Behavior and mechanisms of ciprofloxacin adsorption on aged polylactic acid and polyethlene microplastics

Microplastics (MPs) and antibiotics are emerging pollutants in aquatic environments. MPs can absorb antibiotics, resulting in compound pollution. Batch adsorption experiments were used to investigate the adsorption behavior of CIP on polylactic (PLA) and polyethlene (PE) under various environmental conditions. After a lengthy aging process, both MPs underwent significant physicochemical changes. The equilibrium adsorption capacities of aged PLA and PE were 0.382 mg/g and 0.28 mg/g, respectively, which increased by 18.06% and 75% compared to pristine PLA and PE. The sorption capacity of MPs increased when the pH of the solution approached the dissociation constant (6.09, 8.74) of CIP. When the salinity of the solution was 3.5%, the adsorption capacity of MPs was reduced by more than 65%. The adsorption capacity of MPs rapidly decreased when 20 mg/L fulvic acid was added. Because norfloxacin (NOR) competes for adsorption sites on the microplastic, CIP adsorption is inhibited. Based on the adsorption models, FTIR, and XPS spectra, we demonstrated that the process was monolayer adsorption, with chemical and physical mechanisms including hydrogen bonding, π-π conjugation, ion exchange, and electrostatic interactions controlling it. Thus, PLA and PE microplastics may be a potential vector for CIP in water, and their interaction is mainly influenced by the physicochemical properties of the MPs and environmental factors.

Impact of antibiotics on microbial community in aquatic environment and biodegradation mechanism: a review and bibliometric analysis

Antibiotic residues in aquatic environments pose a potential hazard, and microbes, which play important roles in aquatic ecosystems, are vulnerable to the impacts of antibiotics. This study aimed to analyze the research progress, trends, and hot topics of the impact of antibiotics on microbial community and biodegradation mechanism using bibliometric analysis. An in-depth analysis of the publication characteristics of 6143 articles published between 1990 and 2021 revealed that the number of articles published increased exponentially. The research sites have been mainly concentrated in the Yamuna River, Pearl River, Lake Taihu, Lake Michigan, Danjiangkou Reservoir, etc., illustrating that research around the world is not even. Antibiotics could change the diversity, structure, and ecological functions of bacterial communities, stimulate a widespread abundance of antibiotic-resistant bacteria and antibiotic-resistant genes, and increase the diversity of eukaryotes, thus triggering the shift of food web structure to predatory and pathogenic. Latent Dirichlet allocation theme model analysis showed three clusters, and the research hotspots mainly included the effect of antibiotics on the denitrification process, microplastics combined with antibiotics, and methods for removing antibiotics. Furthermore, the mechanisms of microbe-mediated antibiotic degradation were unraveled, and importantly, we provided bottlenecks and future research perspectives on antibiotics and microbial diversity research.

Electrodegradation of cyclophosphamide in artificial urine by combined methods

The degradation of the chemotherapeutic drug cyclophosphamide in artificial urine was evaluated by Electrochemical Advanced Oxidation Processes (EAOP). The system consisted of an electrochemical flow reactor with a commercial DSA^® electrode (nominal composition Ti / Ru_0,3Ti_0,7O₂) and Ti-mesh cathode. In order to assess the best parameters, the effect of current density, time and flow rate were analyzed using an initial 2³ factorial design. The chosen response variable was the energy efficiency to produce free chlorine species (HClO/ClO^-). After obtaining the most significant factors, the Central Composite Design (CCD) was performed, where the optimum conditions were determined for the current density range (11.714 mA cm^-2 and 66.57 mA cm^-2), flow rate (31.33 mL min^-1) and time range (19 and 37 min). Under an optimized condition, the efficiency of other combined methods (photo-assisted electrochemical, photochemical, sonoelectrochemical and photo-assisted sonoelectrochemical) was evaluated. The efficiency of degradation processes was determined by removal of Chemical Oxygen Demand (COD), creatinine and urea. Analysis by HPLC demonstrates that the cyclophosphamide was substantially removed during the treatment process of ∼77%. Based on these results, it can be observed that the coupling between electrochemical and photochemical processes is a promising alternative for the treatment of this effluent, as a marked reduction of organic matter is observed (63, 94% of creatinine, 29.62% of urea, 39.1% of TOC) and a low treatment cost ratio.

Microwave-Assisted Synthesis of MoS2/BiVO4 Heterojunction for Photocatalytic Degradation of Tetracycline Hydrochloride

Compared with traditional hydrothermal synthesis, microwave-assisted synthesis has the advantages of being faster and more energy efficient. In this work, the MoS₂/BiVO₄ heterojunction photocatalyst was synthesized by the microwave-assisted hydrothermal method within 30 min. The morphology, structure and chemical composition were characterized by X-ray diffraction (XRD), Raman, X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), and high-resolution transmission electron microscopy (HRTEM). The results of characterizations demonstrated that the synthesized MoS₂/BiVO₄ heterojunction was a spherical structure with dimensions in the nanorange. In addition, the photocatalytic activity of the samples was investigated by degrading tetracycline hydrochloride (TC) under visible light irradiation. Results indicated that the MoS₂/BiVO₄ heterojunction significantly improved the photocatalytic performance compared with BiVO₄ and MoS₂, in which the degradation rate of TC (5 mg L^-1) by compound where the mass ratio of MoS₂/BiVO₄ was 5 wt% (MB5) was 93.7% in 90 min, which was 2.36 times of BiVO₄. The active species capture experiments indicated that •OH, •O₂^- and h⁺ active species play a major role in the degradation of TC. The degradation mechanism and pathway of the photocatalysts were proposed through the analysis of the band structure and element valence state. Therefore, microwave technology provided a quick and efficient way to prepare MoS₂/BiVO₄ heterojunction photocatalytic efficiently.

Determination of the microscopic acid dissociation constant of piperacillin and identification of dissociated molecular forms

For amphoteric ß-lactam antibiotics, the acid dissociation constant (pK a) is a fundamental parameter to characterize physicochemical and biochemical properties of antibiotics and to predict persistence and removal of drugs. pK a of piperacillin (PIP) is determined by potentiometric titration with a glass electrode. Electrospray ionization mass spectrometry (ESI-MS) is creatively applied to verify the reasonable pK a value at every dissociation step. Two microscopic pK a values (3.37 ± 0.06 and 8.96 ± 0.10) are identified and attributed to the direct dissociation of the carboxylic acid functional group and one secondary amide group, respectively. Different from other ß-lactam antibiotics, PIP presents a dissociation pattern where direct dissociation is involved instead of protonation dissociation. Moreover, the degradation tendency of PIP in an alkaline solution may alter the dissociation pattern or dismiss the corresponding pK a of the amphoteric ß-lactam antibiotics. This work offers a reliable determination of the acid dissociation constant of PIP and a clear interpretation of the effect of stability of antibiotics on the dissociation process.

Hydrogen Peroxide/Phosphoric Acid Modification of Hydrochars for Sulfamethoxazole and Carbamazepine Adsorption: The Role of Oxygen-Containing Functional Groups

Emerging pollutants, such as sulfonamide antibiotics and pharmaceuticals, have been widely detected in water and soils, posing serious environmental and human health concerns. Thus, it is urgent and necessary to develop a technology for removing them. In this work, a hydrothermal carbonization method was used to prepare the hydrochars (HCs) by pine sawdust with different temperatures. To improve the physicochemical properties of HCs, phosphoric acid (H₃PO₄) and hydrogen peroxide (H₂O₂) were used to modify these HCs, and they were referred to as PHCs and HHCs, respectively. The adsorption of sulfamethoxazole (SMX) and carbamazepine (CBZ) by pristine and modified HCs was investigated systematically. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) results indicated that the H₂O₂/H₃PO₄ modification led to the formation of a disordered carbon structure and abundant pores. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy results suggested that carboxyl (-COOH) and hydroxyl (-OH) functional groups of HCs increased after modification, which is the main reason for the higher sorption of SMX and CBZ on H₃PO₄/H₂O₂-modified HCs when compared with pristine HCs. In addition, the positive correlation between -COOH/C=O and logK_d of these two chemicals also suggested that oxygen-containing functional groups played a crucial role in the sorption of SMX and CBZ. The strong hydrophobic interaction and π-π interaction between CBZ and pristine/modified HCs resulted in its higher adsorption when compared with SMX. The results of this study provide a novel perspective on the investigation of adsorption mechanisms and environmental behaviors for organic contaminants by pristine and modified HCs.

Antibiotic susceptibility pattern of Portuguese environmental Legionella isolates

Introduction

Legionnaires' Disease is a pneumonia caused by Legionella spp., currently treated empirically with fluoroquinolones and macrolides. In this study, we aim to describe the antibiotic susceptibility pattern of environmental Legionella recovered in the south of Portugal.

Methods

Minimal inhibitory concentration (MIC) determination of 57 Legionella isolates (10 Lp sg 1, 32, Lp sg 2-14 15 L. spp) was achieved by broth microdilution, as described by EUCAST, for azithromycin, clarithromycin, ciprofloxacin, levofloxacin, and doxycycline.

Results

Fluoroquinolones were the most active antibiotic, displaying the lowest MIC values in contrast to doxycycline which had the highest. MIC90 and epidemiological cut-off (ECOFF) values were, respectively, 0.5/1 mg/L for azithromycin, 0.125/0.25 mg/L for clarithromycin, 0.064/0.125 mg/L for ciprofloxacin, 0.125/0.125 mg/L for levofloxacin and 16/32 mg/L for doxycycline.

Discussion

MIC distributions were higher than reported by EUCAST for all antibiotics. Interestingly, two phenotypically resistant isolates with high-level quinolone resistance were identified. This is the first time that MIC distributions, lpeAB and tet56 genes have been investigated in Portuguese environmental isolates of Legionella.

Evaluating the spatial and temporal distribution of emerging contaminants in the Pearl River Basin for regulating purposes

Little information is available on how the types, concentrations, and distribution of chemicals have evolved over the years. The objective of the present study is therefore to review the spatial and temporal distribution profile of emerging contaminants with limited toxicology data in the pearl river basin over the years to build up the emerging contaminants database in this region for risk assessment and regulatory purposes. The result revealed that seven groups of emerging contaminants were abundant in this region, and many emerging contaminants had been detected at much higher concentrations before 2011. Specifically, antibiotics, phenolic compounds, and acidic pharmaceuticals were the most abundant emerging contaminants detected in the aquatic compartment, while phenolic compounds were of the most profound concern in soil. Flame retardants and plastics were the most frequently studied chemicals in organisms. The abundance of the field concentrations and frequencies varied considerably over the years, and currently available data can hardly be used for regulation purposes. It is suggested that watershed management should establish a regular monitoring scheme and comprehensive database to monitor the distribution of emerging contaminants considering the highly condensed population in this region. The priority monitoring list should be formed in consideration of historical abundance, potential toxic effects of emerging contaminants as well as the distribution of heavily polluting industries in the region.

Activation of sulfite by micron-scale iron-carbon composite for metronidazole degradation: Theoretical and experimental studies

In recent years, sulfite (S(Ⅳ)), as an alternative to persulfates, has played a crucial role in eliminating antibiotics in wastewater, so there is an urgent need to develop a cheap, environmentally friendly, and effective catalyst. Zero-valent iron (ZVI) has great potential for activated S(Ⅳ) removal of organic pollutants, but its reactivity in water is reduced due to passivation. In this study, a micron-scale iron-carbon composite(mZVI@C-800) prepared via high-temperature calcination was coupled with S(Ⅳ) to degrade metronidazole (MNZ). Under the optimized reaction conditions of mZVI@C-800 dosage of 0.2 g/L and S(Ⅳ) concentration of 0.1 g/L, the MNZ removal rate was up to 81.5 % in acidic and neutral environments. The surface chemical properties of the catalysts were characterized by different analytical techniques, and the corresponding catalytic mechanism was analyzed based on these analytical results. As a result, Fe²⁺ is the main active site, and ^·OH and SO₄^·- were the dominant active species. The increase in efficiency was attributed to the introduction of carbon to enhance the corrosion of mZVI further releasing more Fe²⁺. Additionally proposed were the potential response mechanism, the degradation path, and the toxicity change rule. These results demonstrate that the catalytic breakdown of antibiotics in wastewater treatment can be accelerated by the use of the outstanding catalytic material mZVI@C-800.

Optimizing the multimedia fate model for characterizing environmental risks of florfenicol in seasonally ice-covered reservoirs

Seasonally ice-covered reservoirs have both freeze-thaw and artificial regulation characteristics which could cause the accumulation of antibiotics. Florfenicol, one of the most widely used veterinary antibiotics, with an environmental persistence due to its fluorinated substituents has been detected in the suburban drinking water source reservoirs. In this study, a four-level fugacity model that is appropriate for ice-water-sediment systems was developed to predict the fate of florfenicol and assess its ecological risk in seasonally ice-covered reservoirs. The effects of freeze-thaw and artificial regulation processes on the volume variation of ice and water were considered by the model. The simulation accuracies in ice and water in the model were improved by 3.9% and 17.7%, respectively, compared with the traditional model. The results of mass transfer analysis showed that the inflow of florfenicol in tributaries and the volume variation of ice and water were the major factors influencing the concentration variation of florfenicol in the seasonally ice-covered reservoir. Additionally, ecological risk analysis showed that the values of risk quotients ranged from 0.019 to 0.038 which was consistently at a low ecological risk level. Our findings provide a modeling tool for predicting the fate of antibiotics with persistence and assessing their ecological risks in seasonally freeze-thaw reservoirs in cold regions.

Riverine antibacterial resistance gradient determined by environmental factors

Polluted waterbodies such as rivers provide a pathway or reservoir for bacterial resistance. We studied water quality and bacterial antibacterial resistance along the subtropical Qishan River in Taiwan as a case study of environmental resistance spread in a pristine rural area. Human settlement densities increased generally from pristine mountain sites to the more polluted lowlands. Accordingly, as a working hypothesis, we expected the antibacterial resistance level to increase downstream. We collected sediment samples from 8 stations along the Qishan river and where the Qishan river reaches the Kaoping river. The samples were processed in the lab for bacteriological and physicochemical analysis. Antibacterial resistance was tested with common antibacterial. A comparison was made among the sites where isolates began to occur at the upstream (sites 1-6) with the downstream, including site 7 (Qishan town), site 8 (wastewater treatment plant), and site 9 (Kaoping river). The results of multivariate analysis for bacteriological and physicochemical parameters showed increasing water pollution levels downstream of the Qishan river. Bacterial isolates including Escherichia coli, Klebsiella pneumoniae, Serratia marcescens, Enterobacter sp., Acinetobacter sp., Staphylococcus spp., and Bacillus spp. were analyzed and tested in the study. Their percentage of occurrence varied at each site. The resistance level was determined from the growth inhibition zone diameter (disk diffusion) and the minimum inhibitory concentration (micro-dilution). The results indicated that antibacterial resistance was related to certain environmental factors. Besides, the usage pattern of different classes of antibacterial in different sections could alter trends of their resistance. Bacteria were found with increased resistance to antibacterial used in agriculture through the downstream sites. The WWTP discharging wastewater was demonstrated to be a hotspot of resistance in aquatic environments. In conclusion, bacterial resistance against antibacterial from the Qishan river has become a potential public health threat. This study could assist authorities by providing a reference for risk assessment and management of water quality in Kaohsiung city and southern Taiwan.

Can pharmaceutical pollution alter the spread of infectious disease? A case study using fluoxetine

Human activity is changing global environments at an unprecedented rate, imposing new ecological and evolutionary ramifications on wildlife dynamics, including host-parasite interactions. Here we investigate how an emerging concern of modern human activity, pharmaceutical pollution, influences the spread of disease in a population, using the water flea Daphnia magna and the bacterial pathogen Pasteuria ramosa as a model system. We found that exposure to different concentrations of fluoxetine-a widely prescribed psychoactive drug and widespread contaminant of aquatic ecosystems-affected the severity of disease experienced by an individual in a non-monotonic manner. The direction and magnitude of any effect, however, varied with both the infection outcome measured and the genotype of the pathogen. By contrast, the characteristics of unexposed animals, and thus the growth and density of susceptible hosts, were robust to fluoxetine. Using our data to parameterize an epidemiological model, we show that fluoxetine is unlikely to lead to a net increase or decrease in the likelihood of an infectious disease outbreak, as measured by a pathogen's transmission rate or basic reproductive number. Instead, any given pathogen genotype may experience a twofold change in likely fitness, but often in opposing directions. Our study demonstrates that changes in pharmaceutical pollution give rise to complex genotype-by-environment interactions in its influence of disease dynamics, with repercussions on pathogen genetic diversity and evolution. This article is part of the theme issue 'Infectious disease ecology and evolution in a changing world'.

The Effect of Quinolones on Common Duckweed Lemna minor L., a Hydrophyte Bioindicator of Environmental Pollution

Plant growth and the development of morphological traits in plants are inhibited under exposure to pharmaceuticals that are present in soil and water. The present study revealed that moxifloxacin (MOXI), nalidixic acid (NAL), levofloxacin (LVF) and pefloxacin (PEF) at concentrations of >0.29, >0.48, >0.62 and >1.45 mg × L^-1, respectively, inhibited the growth (Ir) of duckweed plants and decreased their yield (Iy). In the current study, none of the tested quinolones (QNs) at any of the examined concentrations were lethal for common duckweed plants. However, at the highest concentration (12.8 mg × L^-1), LVF increased Ir and Iy values by 82% on average and increased the values of NAL, PEF and MOXI by 62% on average. All tested QNs led to the loss of assimilation pigments. In consequence, all QNs, except for LVF, induced changes in chlorophyll fluorescence (Fv/Fm), without any effect on phaeophytinization quotient (PQ) values. The uptake of NAL, MOXI, LVF by Lemna minor during the 7-day chronic toxicity test was directly proportional to drug concentrations in the growth medium. Nalidixic acid was absorbed in the largest quantities, whereas in the group of fluoroquinolones (FQNs), MOXI, LVF and PEF were less effectively absorbed by common duckweed. This study demonstrated that biosorption by L. minor occurs regardless of the plants' condition. These findings indicate that L. minor can be used as an effective biological method to remove QNs from wastewater and water and that biosorption should be a mandatory process in conventional water and wastewater treatment.

Design Considerations of an ITO-Coated U-Shaped Fiber Optic LMR Biosensor for the Detection of Antibiotic Ciprofloxacin

The extensive use of antibiotics has become a serious concern due to certain deficiencies in wastewater facilities, their resistance to removal, and their toxic effects on the natural environment. Therefore, substantial attention has been given to the detection of antibiotics because of their potential detriment to the ecosystem and human health. In the present study, a novel design of indium tin oxide (ITO) coated U-shaped fiber optic lossy mode resonance (LMR) biosensor is presented for the sensitive detection of the antibiotic ciprofloxacin (CIP). The performance of the designed U-shaped LMR sensor is characterized in terms of its sensitivity, full width at half maximum (FWHM), the figure of merit (FOM), and the limit of detection (LOD). For the proposed U-shaped LMR sensing probe, the various crucial factors such as the thickness (d) of the ITO layer, sensing region length (L), and bending radius (R) are optimized. The thickness of the ITO layer is optimized in such a way that two LMR curves are observed in the transmission spectrum and, thereafter, the performance parameters are evaluated for each LMR. It is observed that the designed U-shaped LMR sensor with optimized parameters shows an approximately seven-fold enhancement in sensitivity compared to the straight-core fiber optic LMR sensor. The numerical results revealed that the designed U-shaped fiber optic LMR biosensor can provide a maximum sensitivity of 17,209.9 nm/RIU with the highest FOM of 91.42 RIU^-1, and LOD of 6.3 × 10^-5 RIU for the detection of CIP hydrochloride in the concentration range of 0.001 to 0.029 mol∙dm^-3. Thus, it is believed that the designed LMR biosensor can practically explore its potential use in environmental monitoring and biomedical applications and hence, opens a new window of opportunity for the researchers working in the field of U-shaped fiber optic LMR biosensing.

Bismuth-based nanostructured photocatalysts for the remediation of antibiotics and organic dyes

A serious threat to human health and the environment worldwide, in addition to the global energy crisis, is the increasing water pollution caused by micropollutants such as antibiotics and persistent organic dyes. Nanostructured semiconductors in advanced oxidation processes using photocatalysis have recently attracted a lot of interest as a promising green and sustainable wastewater treatment method for a cleaner environment. Due to their narrow bandgaps, distinctive layered structures, plasmonic, piezoelectric and ferroelectric properties, and desirable physicochemical features, bismuth-based nanostructure photocatalysts have emerged as one of the most prominent study topics compared to the commonly used semiconductors (TiO₂ and ZnO). In this review, the most recent developments in the use of photocatalysts based on bismuth (e.g., BiFeO₃, Bi₂MoO₆, BiVO₄, Bi₂WO₆, Bi₂S₃) to remove dyes and antibiotics from wastewater are thoroughly covered. The creation of Z-schemes, Schottky junctions, and heterojunctions, as well as morphological modifications, doping, and other processes are highlighted regarding the fabrication of bismuth-based photocatalysts with improved photocatalytic capabilities. A discussion of general photocatalytic mechanisms is included, along with potential antibiotic and dye degradation pathways in wastewater. Finally, areas that require additional study and attention regarding the usage of photocatalysts based on bismuth for removing pharmaceuticals and textile dyes from wastewater, particularly for real-world applications, are addressed.

Sulfur: a neglected driver of the increased abundance of antibiotic resistance genes in agricultural reclaimed subsidence land located in coal mines with high phreatic water levels

Due to the shallow burial of groundwater in coal mines with a high phreatic water level, a large area of subsidence lakes is formed after the mine collapses. Agricultural and fishery reclamation activities have been carried out, which introduced antibiotics and exacerbated the contamination of antibiotic resistance genes (ARGs), but this has received limited attention. This study analyzed ARG occurrence in reclaimed mining areas, the key impact factors, and the underlying mechanism. The results show that sulfur is the most critical factor impacting the abundance of ARGs in reclaimed soil, which is due to changes in the microbial community. The species and abundance of ARGs in the reclaimed soil were higher than those in the controlled soil. The relative abundances of most ARGs increased with the depth of reclaimed soil (from 0 to 80 cm). In addition, the microbial structures of the reclaimed and controlled soils were significantly different. Proteobacteria, was the most dominant microbial phylum in the reclaimed soil. This difference is likely related to the high abundance of sulfur metabolism functional genes in the reclaimed soil. Correlation analysis showed that the differences in ARGs and microorganisms in the two soil types were highly correlated with the sulfur content. High levels of sulfur promoted the proliferation of sulfur-metabolizing microbial populations such as Proteobacteria and Gemmatimonadetes in the reclaimed soils. Remarkably, these microbial phyla were the main antibiotic-resistant bacteria in this study, and their proliferation created conditions for the enrichment of ARGs. Overall, this study underscores the risk of the abundance and spread of ARGs driven by high-level sulfur in reclaimed soils and reveals the mechanisms.

A novel BC/g-C3N4 porous hydrogel carrier used in intimately coupled photocatalysis and biodegradation system for efficient removal of tetracycline hydrochloride in water

Intimately coupled photocatalysis and biodegradation (ICPB) is a promising technology to remove refractory contaminants from water. The key to successful ICPB is a carrier capable of accumulating biofilm and adhering photocatalyst firmly. Herein, BC/g-C₃N₄ was prepared into a three dimensional porous hydrogel and used as a carrier in ICPB system for the first time. Degradation experiments revealed that the removal rate of tetracycline hydrochloride (TCH) in water by the ICPB system was 96.0% after 10 h, which was significantly higher than that by the photocatalysis (PC, 76.3%), biodegradation (B, 32.5%), adsorption (AD, 17.2%), and photolysis (P, 5.0%) systems. Photo-electrochemical tests confirmed that ICPB system had superior electron transfer ability between photocatalysts and microorganisms. The removal efficiency of COD proved that microorganisms played an important role in the mineralization process of TCH by the ICPB system. After the ICPB degradation experiment, microorganisms maintained high activity and Pseudomonas, Burkholderiaceae and Flavobacterium which had TCH degradation or electron transport ability, were enriched. In conclusion, the novel ICPB carrier overcame shortcomings of the traditional ICPB carrier and the novel ICPB system had superior degradation performance for TCH. This study provided a possible method to promote the practical application of ICPB technology.

Occurrence, spatial distribution and ecological risks of antibiotics in soil in urban agglomeration

Antibiotics in soil environment are regarded as emerging pollutants and have introduced increasing risks to soil ecosystem and human health in rapid urbanization areas. Identifying the occurrence and spatial variability of antibiotics in soils is an urgent issue in sustaining soil security. In this study, antibiotics in soils were investigated and analyzed in Beijing-Tianjin-Hebei urban agglomeration. The occurrence, spatial distribution, and related affecting factors of antibiotics in soils were identified and ecological risks of antibiotics in soil environment were assessed. Results showed that (1) The mean concentration of soil antibiotics in Beijing-Tianjin-Hebei urban agglomeration was 21.79 µg/kg. Land use substantially affected the occurrence and concentration of antibiotics in soils. Concentrations of antibiotics in cropland and orchard soils were 2-3 times higher than the other land use types. (2) The concentrations of antibiotics in soils in Beijing-Tianjin-Hebei urban agglomeration presented a spatial pattern of high values in southeast, and low values in northwest. Spatial variability of antibiotics in soils was closely related to the application of organic fertilizer and wastewater irrigation as well as topographical features. Furthermore, soil properties and land management policy had substantial influences on soil antibiotics, and soil heavy metals may aggravate the accumulation of antibiotics in soils. (3) Ecological risks assessment of antibiotics in soils demonstrated that erythromycin (ERY), sulfamethoxazole (SMX), and doxycycline (DOX) may introduce high risks to soil ecosystem health, and more attention should be paid to the areas with intensive human activities that had potential high risk to soil ecosystem health. This study suggests that scientific land and soil management should be considered to prevent soil antibiotic pollution and sustain soil security in urban agglomeration.

Environmental risk caused by drug waste in the city of Rio de Janeiro, Brazil, during the SARS-Cov19 pandemic

Abstract The relationship between the distribution of medicines used in the Pandemic by SARS-COV-19 in the municipality of Rio de Janeiro and the estimated level of environmental risk caused by their residues was evaluated. The amount of medicines distributed by primary health care (PHC) units between 2019 and 2021 were collected. The risk quotient (RQ) corresponded to the ratio between the estimated predictive environmental concentration (PECest) obtained by the consumption and excretion of each drug and its non-effective predictive concentration (PNEC). Between 2019 and 2020, the PECest of azithromycin (AZI) and ivermectin (IVE) increased between 2019 and 2020, with a decrease in 2021 probably due to shortages. Dexchlorpheniramine (DEX) and fluoxetine (FLU) fell, returning to growth in 2021. While the PECest of diazepam (DIA) increased over these 3 years, ethinylestradiol (EE2) decreased possibly due to the prioritization of PHC in the treatment of COVID-19. The largest QR were from FLU, EE2 and AZI. The consumption pattern of these drugs did not reflect their environmental risk because the most consumed ones have low toxicity. It is worth noting that some data may be underestimated due to the incentive given during the pandemic to the consumption of certain groups of drugs.

Environmental risk caused by drug waste in the city of Rio de Janeiro, Brazil, during the SARS-Cov19 pandemic

The relationship between the distribution of medicines used in the Pandemic by SARS-COV-19 in the municipality of Rio de Janeiro and the estimated level of environmental risk caused by their residues was evaluated. The amount of medicines distributed by primary health care (PHC) units between 2019 and 2021 were collected. The risk quotient (RQ) corresponded to the ratio between the estimated predictive environmental concentration (PECest) obtained by the consumption and excretion of each drug and its non-effective predictive concentration (PNEC). Between 2019 and 2020, the PECest of azithromycin (AZI) and ivermectin (IVE) increased between 2019 and 2020, with a decrease in 2021 probably due to shortages. Dexchlorpheniramine (DEX) and fluoxetine (FLU) fell, returning to growth in 2021. While the PECest of diazepam (DIA) increased over these 3 years, ethinylestradiol (EE2) decreased possibly due to the prioritization of PHC in the treatment of COVID-19. The largest QR were from FLU, EE2 and AZI. The consumption pattern of these drugs did not reflect their environmental risk because the most consumed ones have low toxicity. It is worth noting that some data may be underestimated due to the incentive given during the pandemic to the consumption of certain groups of drugs.

Seasonal distribution and dynamic evolution of antibiotics and evaluation of their resistance selection potential and ecotoxicological risk at a wastewater treatment plant in Jinan, China

The seasonal distribution and dynamic evolution of antibiotics in wastewater from main treatment areas and in sludge and their resistance selection potential and ecotoxicological risk were studied at a municipal wastewater treatment plant in Jinan, East China. Ten antibiotics were selected, and all were detected in wastewater and sludge samples, with fluoroquinolones showing the highest detection concentrations and frequencies. Seasonal fluctuations in the antibiotic concentrations in the influent, effluent, and sludge were observed, with the highest values in winter in most cases. The dynamic evolution of antibiotics during the treatment process differed among the seasons. The antibiotic removal efficiencies were incomplete, ranging from - 40.47 to 100%. Mass balance analysis showed that sulfonamides, roxithromycin, and metronidazole were mainly removed through biological processing, whereas fluoroquinolones, doxycycline, and chloramphenicol were removed through sludge adsorption. Levofloxacin, as well as a mixture of the 10 antibiotics from the effluent, could pose a low ecotoxicological risk to Daphnia in the receiving waters. Additionally, levofloxacin and ciprofloxacin in the effluent and ciprofloxacin and metronidazole in the sludge may facilitate the selection of antibiotic-resistant bacteria in the environment.

How do freshwater microalgae and cyanobacteria respond to antibiotics?

Antibiotic pollution is an emerging environmental challenge. Residual antibiotics from various sources, including municipal and industrial wastewater, sewage discharges, and agricultural runoff, are continuously released into freshwater environments, turning them into reservoirs that contribute to the development and spread of antibiotic resistance. Thus, it is essential to understand the impacts of antibiotic residues on aquatic organisms, especially microalgae and cyanobacteria, due to their crucial roles as primary producers in the ecosystem. This review summarizes the effects of antibiotics on major biological processes in freshwater microalgae and cyanobacteria, including photosynthesis, oxidative stress, and the metabolism of macromolecules. Their adaptive mechanisms to antibiotics exposure, such as biodegradation, bioadsorption, and bioaccumulation, are also discussed. Moreover, this review highlights the important factors affecting the antibiotic removal pathways by these organisms, which will promote the use of microalgae-based technology for the removal of antibiotics. Finally, we offer some perspectives on the opportunities for further studies and applications.

Synthetic biology-based bioreactor and its application in biochemical analysis

In the past few years, synthetic biologists have established some biological elements and bioreactors composed of nucleotides under the guidance of engineering methods. Following the concept of engineering, the common bioreactor components in recent years are introduced and compared. At present, biosensors based on synthetic biology have been applied to water pollution monitoring, disease diagnosis, epidemiological monitoring, biochemical analysis and other detection fields. In this paper, the biosensor components based on synthetic bioreactors and reporters are reviewed. In addition, the applications of biosensors based on cell system and cell-free system in the detection of heavy metal ions, nucleic acid, antibiotics and other substances are presented. Finally, the bottlenecks faced by biosensors and the direction of optimization are also discussed.

Non-metal activated peroxydisulfate by straw biochar for tetracycline hydrochloride oxidative degradation: catalytic activity and mechanism

In this study, stalk biochar (BC) was prepared by a high-temperature pyrolysis process and used as a non-metallic catalyst to activate peroxydisulfate (PDS) to degrade tetracycline hydrochloride (TCH). Various characterization results showed that BC had a hollow tubular structure, irregular folds, and important active sites such as oxygen-containing functional groups. Under the optimal reaction conditions, the degradation rate of TCH reached 98.1% within 120 min. In addition, the degradation performance was satisfactory and similar under acidic and near neutral pH, and higher temperature promoted the degradation of TCH. The SO₄·^-, ·OH, and ¹O₂ generated by PDS activation were reactive oxygen species (ROS), which degraded TCH through free radical/non-radical synergistic pathways. Quenching experiments proved that the generated SO₄·^- and ·OH might be the dominant reactive oxygen species (ROS) during the oxidative reaction. The research results will provide a theoretical basis for the application of PDS activated by non-metallic catalysts in the remediation of tetracycline antibiotics pollution.

Antimicrobial and the Resistances in the Environment: Ecological and Health Risks, Influencing Factors, and Mitigation Strategies

Antimicrobial contamination and antimicrobial resistance have become global environmental and health problems. A large number of antimicrobials are used in medical and animal husbandry, leading to the continuous release of residual antimicrobials into the environment. It not only causes ecological harm, but also promotes the occurrence and spread of antimicrobial resistance. The role of environmental factors in antimicrobial contamination and the spread of antimicrobial resistance is often overlooked. There are a large number of antimicrobial-resistant bacteria and antimicrobial resistance genes in human beings, which increases the likelihood that pathogenic bacteria acquire resistance, and also adds opportunities for human contact with antimicrobial-resistant pathogens. In this paper, we review the fate of antimicrobials and antimicrobial resistance in the environment, including the occurrence, spread, and impact on ecological and human health. More importantly, this review emphasizes a number of environmental factors that can exacerbate antimicrobial contamination and the spread of antimicrobial resistance. In the future, the timely removal of antimicrobials and antimicrobial resistance genes in the environment will be more effective in alleviating antimicrobial contamination and antimicrobial resistance.

Ecology, more than antibiotics consumption, is the major predictor for the global distribution of aminoglycoside-modifying enzymes

Antibiotic consumption and its abuses have been historically and repeatedly pointed out as the major driver of antibiotic resistance emergence and propagation. However, several examples show that resistance may persist despite substantial reductions in antibiotic use, and that other factors are at stake. Here, we study the temporal, spatial, and ecological distribution patterns of aminoglycoside resistance, by screening more than 160,000 publicly available genomes for 27 clusters of genes encoding aminoglycoside-modifying enzymes (AME genes). We find that AME genes display a very ubiquitous pattern: about 25% of sequenced bacteria carry AME genes. These bacteria were sequenced from all the continents (except Antarctica) and terrestrial biomes, and belong to a wide number of phyla. By focusing on European countries between 1997 and 2018, we show that aminoglycoside consumption has little impact on the prevalence of AME-gene-carrying bacteria, whereas most variation in prevalence is observed among biomes. We further analyze the resemblance of resistome compositions across biomes: soil, wildlife, and human samples appear to be central to understand the exchanges of AME genes between different ecological contexts. Together, these results support the idea that interventional strategies based on reducing antibiotic use should be complemented by a stronger control of exchanges, especially between ecosystems.

Risk ranking of macrolide antibiotics - Release levels, resistance formation potential and ecological risk

Antibiotic resistance (AR) development in natural water bodies is a significant source of concern. Macrolide antibiotics in particular have been identified as pollutants of concern for AR development throughout the literature, as well as by state and international authorities. This study utilises a probabilistic model to examine the risk of AR development arising from human-use macrolide residues, utilising administration rates from Ireland as a case study. Stages modelled included level of administration, excretion, degradation in wastewater, removal in wastewater treatment, assuming conventional activated sludge (CAS) treatment, and dilution. Release estimates per day, as well as risk quotient values for antibiotic resistance development and ecological impact, are generated for erythromycin, clarithromycin, and azithromycin. In the modelled scenario in which conventional activated sludge treatment is utilised in wastewater treatment, this model ranks risk of resistance development for each antibiotic in the order clarithromycin > azithromycin > erythromycin, with mean risk quotient values of 0.50, 0.34 and 0.12, respectively. A membrane bioreactor scenario was also modelled, which reduced risk quotient values for all three macrolides by at least 50 %. Risk of ecological impact for each antibiotic was also examined, by comparing environmental concentrations predicted to safety limits based on toxicity data for cyanobacteria and other organisms from the literature, with azithromycin being identified as the macrolide of highest risk. This study compares and quantifies the risk of resistance development and ecological impact for a high-risk antibiotic group in the Irish context, and demonstrates the potential for risk reduction achieved by adoption of alternative (e.g. membrane bioreactor) technology.

Ex-situ magnetic activated carbon for the adsorption of three pharmaceuticals with distinct physicochemical properties from real wastewater

Pharmaceuticals are able to evade conventional wastewater treatments and therefore, are recurrently found in the environment with proven potential to cause harm to human and wildlife. Adsorption onto activated carbon (AC) is a promising complement. However, AC production from non-renewable resources and its difficult after-use recuperation are prohibitive. Hence, a waste-based magnetic activated carbon (MAC) was produced from paper mill sludge, via an ex-situ synthesis, for the adsorptive removal of carbamazepine (CBZ), sulfamethoxazole (SMX) and ibuprofen (IBU) from ultrapure water and wastewater. The MAC was obtained through the promotion of electrostatic interactions between magnetic and activated carbon particles in a water suspension at controlled pH between the points of zero charge of both surfaces. The optimized condition (MACX3) presented remarkable properties regarding specific surface area (S_BET=795 m² g^-1) and saturation magnetization (M_S=19 emu g^-1). Kinetic and equilibrium adsorption studies were performed under batch conditions. Adsorption equilibrium was reached in up to 30 min for all pharmaceuticals in both matrices, proving the low dependence on the adsorbate and the broad applicability of MACX3 in pharmaceutical adsorption. Regarding equilibrium experiments, high Langmuir maximum adsorption capacities (q_m) were achieved in ultrapure water (up to 711 ± 40 µmol g^-1). Equilibrium studies in wastewater revealed a decay in q_m when compared to ultrapure water: 28% for CBZ (468 ± 20 µmol g^-1 (111 ± 5 mg g^-1)), 78% for SMX (145 ± 10 µmol g^-1 (37 ± 3 mg g^-1)) and 62% for IBU (273 ± 8 µmol g^-1 (56 ± 2 mg g^-1)), attributed to the wastewater pH, which dictates the speciation of the pharmaceuticals and controls electrostatic interactions between pharmaceuticals and MAC, and to competition effects by organic matter. It was demonstrated the promising applicability of a waste-based ex-situ MAC, rapidly retrievable from water, as an alternative tertiary wastewater treatment for pharmaceuticals removal.

Antibiotics disrupt lipid metabolism in zebrafish (Danio rerio) larvae and 3T3-L1 preadipocytes

Antibiotics are emerging environmental contaminants with wide attention due to their high consumption and pseudo-persistence in the environment. They have been shown to induce obesity or obesity-related metabolic diseases in experimental animals, but the underlying toxicological mechanisms remain unclear. Here, the disruptive effects of four commonly used antibiotics, namely doxycycline (DC), enrofloxacin (ENR), florfenicol (FF) and sulfamethazine (SMT) on lipid metabolism were investigated in zebrafish (Danio rerio) larvae and murine preadipocyte cell line. Triglyceride (TG) content was reduced after 1 ng/L DC or ENR exposure but was increased at higher concentrations up to 100 mg/L. FF increased and SMT reduced TG content but did not show any concentration dependence. None of the antibiotics had any significant effect on total cholesterol (TC) content in zebrafish except 100 μg/L SMT. Expression levels of 8 lipid metabolism-related genes were also quantified. SMT was most disruptive by up-regulating six genes, followed by FF which up-regulated four genes and down-regulated one gene, whereas DC and ENR both up-regulated one gene. In 3T3-L1 preadipocytes, ENR, FF, and SMT in general increased TG content, while 100 mg/L FF reduced TG substantially. DC did not show any effect up to 10 mg/L, at which TG increased significantly. FF and SMT increased TC slightly at low concentrations but reduced it at high concentrations, whereas TC, DC and ENR had no effect at any tested concentrations. Gene expression measurement also indicated that SMT was most disruptive, followed by FF, DC, and ENR. Reporter gene assays showed that only SMT inhibited the transcriptional activity of peroxisome proliferator-activated receptor γ (PPARγ). The above experimental results and clustering analysis demonstrate that the four antibiotics exerted disruption on lipid metabolism through different mechanisms, and one of the mechanisms for SMT may be inhibition of PPARγ transcriptional activity.

Enrofloxacin exposure induces anxiety-like behavioral responses in zebrafish by affecting the microbiota-gut-brain axis

The ubiquitous presence of antibiotic residues in aqueous environments poses a great potential threat to aquatic organisms. Nevertheless, the behavioral effects of environmentally realistic levels of antibiotics remain poorly understood in fish species. In this study, the behavioral impacts of enrofloxacin, one of typical fluoroquinolone antibiotics that is frequently detected in aquatic environments, were evaluated by the classic light-dark test (LDT) and novel tank task (NTT) in zebrafish. Furthermore, the effects of enrofloxacin exposure on the microbiota-gut-brain axis were also assessed to reveal potential affecting mechanisms underlying the behavioral abnormality observed. Our results demonstrated that zebrafish exposed to 60 μg/L enrofloxacin for 28 days took significantly longer to enter the stressful area of the testing tank and spent significantly less time there in both the LDT and NTT, indicating abnormal anxiety-like behaviors induced by the exposure. In addition, exposure to enrofloxacin at 6 and 60 μg/L resulted in a significant elevation in Bacteroidetes and a marked decline in the Firmicutes/Bacteroidetes ratio of the gut microbiota. Moreover, the intestinal contents of interleukin 6 (IL-6), tumor necrosis factor-alpha (TNF-α), glucagon-like peptide 1 (GLP-1), and 5-hydroxytryptamine (5-HT) in zebrafish were significantly upregulated, whereas those of plasma adrenocorticotropic hormone (ACTH) and cortisol (COR) were markedly downregulated upon enrofloxacin exposure. Incubation of zebrafish with a high dose of enrofloxacin (60 μg/L) also resulted in evident increases in the contents of corticotropin-releasing hormone (CRH), brain-derived neurotrophic factor (BDNF), and neuropeptide Y (NPY) in the brain. Fortunately, no significant alteration in the expression of glial fibrillary acidic protein (GFAP) was detected in the brain after enrofloxacin exposure. Our findings suggest that the disruption of the microbiota-gut-brain axis may account for enrofloxacin-induced anxiety-like behaviors in zebrafish. Since the disruption of microbiota-gut-brain axis may give rise to various clinical symptoms, the health risk of antibiotic exposure deserves more attention.

Novel preparation of red fluorescent carbon dots for tetracycline sensing and its application in trace determination

The controllable design of red-emitting carbon dots and further exploration of their application in the trace determination of environmental pollutants remains a tremendous challenge. Herein, the novel strategy for red fluorescent carbon dots (R-CDs) with a higher quantum yield of 58.9% was proposed by doping small-molecule urea into the bio-dye of resazurin for the first time, which can retain the luminophore of precursors and exhibit exceptional optical, advantageous reversibility and outstanding photostability. Importantly, the R-CDs exhibit a remarkable fluorescence reduction towards tetracyclines (TCs) accompanied by a noticeable color change of R-CDs solution from red to yellow, which can realize the trace detection of TCs at strelatively low levels, including tetracycline (TC), oxytetracycline (OTC), and chlortetracycline (CTC). The linear range of TC, CTC, and OTC are 3-40 μM, 4-50 μM, and 2-50 μM, and the corresponding detection limits are 38.5 nM, 64.6 nM, and 45.4 nM, respectively (S/N = 3). Furthermore, the R-CDs demonstrate sensitivity to the physiological pH in the linear range of 4.0-5.0 and 5.0-6.2 with a pKa of 5.61. As a multifunctional fluorescent sensor, R-CDs can provide a new perspective for the preparation of long-wavelength CDs, and further realize the trace determination of environmental pollutants.

Silver nanoparticles modified ZnO nanocatalysts for effective degradation of ceftiofur sodium under UV-vis light illumination

Light-induced photocatalytic degradation of ceftiofur sodium (CFS) has been assessed in the presence of plasmonic zinc oxide nanostructures (ZnONSTs), like, ZnO nanoparticles, ZnO nanorods (ZnONRs) and ZnO nanoflowers (ZnONFs). Silver nanoparticles (Ag NPs) loaded ZnO nanostructures (Ag-ZnONSTs) are obtained through seed-assisted chemical reaction followed by chemical reduction of silver. The surface modification of ZnO nanostructures by Ag NPs effectually altered their optical properties. Further, the surface plasmonic effect of Ag NPs facilitates visible light absorption by ZnONSTs and improved the photogenerated electron and hole separation, which makes the ZnONSTs a more active photocatalyst than TiO₂ (P25) nanoparticles. Especially, Ag-ZnONRs showed higher CFS oxidation rate constant (k' = 4.6 × 10^-4 s^-1) when compared to Ag-ZnONFs (k' = 2.8 × 10^-4 s^-1) and Ag-ZnONPs (k' = 2.5 × 10^-4 s^-1), owing to their high aspect ratio (60:1). The unidirectional transport of photogenerated charge carriers on the Ag-ZnONRs may be accountable for the observed high photocatalytic oxidation of CFS. The photocatalytic oxidation of CFS mainly proceeds through ^•OH radicals generated on the Ag-ZnONRs surface under light illumination. In addition, heterogeneous activation of peroxymonosulfate by Ag-ZnONRs accelerates the rate of photocatalytic mineralization of CFS. The quantification of oxidative radicals supports the proposed CFS oxidation mechanism. Stability studies of plasmonic Ag-ZnONSTs strongly suggests that it could be useful to clean large volume of pharmaceutical wastewater under direct solar light irradiation.

Adsorption of Fluoroquinolone Antibiotics from Water and Wastewater by Colemanite

Pharmaceutical residues in water and wastewater have become a worldwide problem with environmental and public health consequences. Antibiotics are of special importance because of the emergence of antibiotic-resistant genes. This study evaluates the adsorptive removal of four common fluoroquinolone antibiotics by using natural colemanite as an alternative adsorbent for the first time. Batch adsorption experiments were conducted for the mixture of fluoroquinolones as well as for individual compounds during the isotherm studies. Adsorption kinetic results indicated that the process followed the pseudo-second-order (PSO) model, while the Langmuir model described the sorption isotherms. The effects of pH and temperature on adsorption performance were determined, and the results indicated that the adsorption was endothermic and spontaneous, with increasing randomness at the solid-liquid interface. The effects of real water and wastewater matrices were tested by using tap water, surface water, and wastewater samples. Reusability experiments based on five adsorption-desorption cycles indicated that the adsorption performance was mostly retained after five cycles. The adsorption mechanism was elucidated based the material characterization before and after adsorption. The results indicate that colemanite can be used as an effective and reusable adsorbent for fluoroquinolone antibiotics as well as for other pollutants with similar physicochemical properties.

Heterogeneous activation of peroxymonosulfate by magnetic hybrid CuFe2O4@N-rGO for excellent sulfamethoxazole degradation: Interaction of CuFe2O4 with N-rGO and synergistic catalytic mechanism

In order to address the low catalytic performance of magnetic CuFe₂O₄ caused by the agglomeration, low conductivity and potential metal ion leaching risk, N-doped reduced graphene oxide (N-rGO) with high charge density and rich active sites was employed as support to synthesize CuFe₂O₄@N-rGO (CuFe@NG), which was used for peroxymonosulfate (PMS) activation to degrade sulfamethoxazole (SMX). Results showed that the CuFe@NG/PMS system exhibited excellent degradation rate and mineralization efficiency on SMX in 60 min, which exceeded 93.15% and 31.96%, respectively. Besides, its degradation rate constants was 1.68 times higher than that of the CuFe₂O₄/PMS system. The enhanced performance could be mainly ascribed to the efficient synergistic activation of PMS by two components: I. the successful dispersion of CuFe₂O₄ on N-rGO and the interaction between them exposed more Fe³⁺-O^2- and Cu²⁺-O^2- active sites via decreasing size and aggregation of CuFe₂O₄ particles; II. the supported N-rGO supplied extra CO, C-OH and C-NC active groups, resulting in a large number of π electrons; III. the pyrrole N formed by further doping of N could activate the π electrons and reduce the energy barrier of electron transfer. The abundant active groups and sites and excellent electron transfer ability co-accelerate the production of active species. Specifically, surface-bound radical (•OH, SO₄^•-) and singlet oxygen ¹O₂ played a dominant role according to ESR and quenching tests. Furthermore, M-O-C binding site between two components enhanced catalyst stability and reduced metal leaching, leading to its availability on reusability in the 5 cyclic experiments. Lastly, CuFe@NG/PMS system also possessed a strong application ability in actual aquatic environment for SMX treatment.

UV and chemical aging alter the adsorption behavior of microplastics for tetracycline

This study evaluates the "vector" effects of different microplastics (MPs) on coexisting pollutants. The adsorption of tetracycline was studied on biodegradable plastics poly(butylene adipate-co-terephthalate) (PBAT) and non-biodegradable plastics polystyrene (PS), polypropylene (PP), and polyethylene (PE) after UV aging and chemical aging. The physicochemical properties of PBAT changed more obviously after UV radiation and chemical aging comparing to PS, PP and PE. Pores and cracks appear on the surface of aged PBAT. The crystallinity increased from 29.2% to 52.62%. In adsorption experiments, pristine and aged PBAT had strong vector effects on the adsorption of tetracycline than PS, PP and PE. The adsorption capacity of tetracycline on PBAT was increased from 0.7980 mg g^-1 to 1.2669 mg g^-1 after chemical aging. The adsorption mechanism indicated that electrostatic interactions and hydrogen bonds contribute to the adsorption process. In addition, for the adsorption of tetracycline on PS, π-π interaction was the main cause, and the adsorption mechanism was not considerably changed by aging. In conclusion, this study demonstrates that biodegradable plastics have substantial vector effect on coexisting pollutants at the end of their life cycle, this contributes to assessment of the risk from microplastic pollution.

Antibiotics in a seasonal ice-sealed reservoir: Occurrence, temporal variation, prioritization, and source apportionment

Antibiotics are prevalent in the aquatic environment as emerging contaminants. Their knowledge of seasonal ice-sealed reservoirs, however, is limited. The occurrence, temporal variation, and prioritization of twenty-three antibiotics in Shitoukoumen Reservoir during its ice-free and ice-sealed periods, as well as the source apportionment of the high-priority antibiotics, were investigated in this study. The results showed that florfenicol was the dominant antibiotic in Shitoukoumen Reservoir, with different median concentrations of 75.0 ± 6.5 ng L^-1 and 7.0 ± 1.7 ng kg^-1 in the water and ice, respectively. The concentrations of florfenicol, sulfaguanidine, and sulfamonomethoxine in the water of the reservoir water varied over time, but their monthly mass loads from inflow rivers were similar during ice-free and ice-sealed periods. This indicated that other factors, such as aquacultural practice, non-point source rain runoff, and the blocking effect of ice, determined the temporal variations of the three antibiotics and resulted in their relatively high concentrations during the ice-free period. High-priority antibiotics included erythromycin, florfenicol, ofloxacin, sarafloxacin, sulfaquinoxaline, thiamphenicol, and tylosin. Aquaculture was the primary source of high-priority antibiotics, accounting for 67.3 % and 59.4 % of the total high-priority antibiotic concentrations during ice-free and ice-sealed periods, respectively. The findings suggest that aquaculture, rain runoff, and ice blocking should all be considered as factors influencing antibiotic variations in a seasonal ice-sealed reservoir.

Sediment metagenomics reveals the impacts of poultry industry wastewater on antibiotic resistance and nitrogen cycling genes in tidal creek ecosystems

The intensification of the poultry industry may lead to the increased spread of antibiotic resistance genes (ARGs) in the environment. However, the impacts of wastewater discharge from poultry processing plants on the sediment resistome are relatively unexplored. Furthermore, its relationships with important biogeochemical pathways, such as the N cycle, are virtually unknown. The overall objective of this study was to examine the abundance and diversity of antibiotic resistance and N cycling genes in sediment microbial communities impacted by poultry industry wastewater. We performed a metagenomic investigation of sediments in an impacted and a reference tidal creek. We also quantified the abundance of the clinical class 1 integron-integrase gene (intI1) through qPCR as a secondary marker of anthropogenic contamination. Abundance and diversity of ARGs were substantially higher in the impacted tidal creek, especially near the wastewater discharge. Abundances of ARGs conferring resistance to macrolides, tetracyclines, and streptogramins were also higher in the impacted creek than the reference creek. From the N cycling genes detected in the metagenomes, nrfA, the genetic marker for dissimilatory nitrate reduction to ammonia (DNRA), had the strongest positive relationship with the total abundance of ARGs, which may indicate an increased potential of eutrophication in ARG-impacted ecosystems due to nitrogen retention. This study demonstrates that wastewater discharge from a poultry processing plant can increase the spread of ARGs, which may result in negative impacts on ecosystem health.

New europium-doped carbon nanoparticles showing long-lifetime photoluminescence: Synthesis, characterization and application to the determination of tetracycline in waters

The growing appearance of antibiotic-resistant strains of microorganisms originated from the widespread use and ubiquitous presence of such drugs is a major concern in the world. The development of methodologies able to detect such substances at low concentration in real water samples is mandatory to overcome this problem. Europium(III) is known to form complexes with tetracycline (TC) with photoluminescent characteristics useful for TC determination. In the present work, we synthesized for the first time carbon nanoparticles (CN) showing delayed photoluminescence using a Europium(III) doping synthesis. The new material (PCNEu) was characterized both morphologically and spectroscopically, showing an analytical photoluminescent signal in presence of TC, arising from the ⁵D₀→⁷F₂ transition of europium, one hundred times higher than that of the europium salt alone in presence of the antibiotic. This enhancement is a consequence of the amplifying effect exerted by nanoparticle structure itself, leading to an efficient synergistic "antenna effect" in the system PCNEu - TC. The analytical signal is affected both by pH and the nature of the buffer used, and it allows the detection of tetracycline in waters with a limit of detection of 2.18 nM and recoveries between 90 and 110%. The analytical performance of the developed methodology enables having lower limits of detection than other luminescent and chemiluminescent reported methodologies.

Fish and macroinvertebrate assemblages reveal extensive degradation of the world's rivers

Rivers suffer from multiple stressors acting simultaneously on their biota, but the consequences are poorly quantified at the global scale. We evaluated the biological condition of rivers globally, including the largest proportion of countries from the Global South published to date. We gathered macroinvertebrate- and fish-based assessments from 72,275 and 37,676 sites, respectively, from 64 study regions across six continents and 45 nations. Because assessments were based on differing methods, different systems were consolidated into a 3-class system: Good, Impaired, or Severely Impaired, following common guidelines. The proportion of sites in each class by study area was calculated and each region was assigned a Köppen-Geiger climate type, Human Footprint score (addressing landscape alterations), Human Development Index (HDI) score (addressing social welfare), % rivers with good ambient water quality, % protected freshwater key biodiversity areas; and % of forest area net change rate. We found that 50% of macroinvertebrate sites and 42% of fish sites were in Good condition, whereas 21% and 29% were Severely Impaired, respectively. The poorest biological conditions occurred in Arid and Equatorial climates and the best conditions occurred in Snow climates. Severely Impaired conditions were associated (Pearson correlation coefficient) with higher HDI scores, poorer physico-chemical water quality, and lower proportions of protected freshwater areas. Good biological conditions were associated with good water quality and increased forested areas. It is essential to implement statutory bioassessment programs in Asian, African, and South American countries, and continue them in Oceania, Europe, and North America. There is a need to invest in assessments based on fish, as there is less information globally and fish were strong indicators of degradation. Our study highlights a need to increase the extent and number of protected river catchments, preserve and restore natural forested areas in the catchments, treat wastewater discharges, and improve river connectivity.

Assessment of sulfamethoxazole toxicity to marine mussels (Mytilus galloprovincialis): Combine p38-MAPK signaling pathway modulation with histopathological alterations

Sulfamethoxazole (SMX), is a ubiquitous antibiotic in the aquatic environment and received concerns on its health hazards, especially its sub-lethal effects on non-target organisms which were remained largely unknown. In the present study, in order to investigate SMX induced tissue damages and reveal underlying mechanisms, marine mussels, Mytilus galloprovincialis were challenged to SMX series (0.5, 50 and 500 μg/L) for six-days followed by six-day-recovery. Comprehensive histopathological alteration (including qualitative, semi-quantitative and quantitative indices), together with transcriptional and (post-) translational responses of key factors (p38, NFκB and p53) in the p38-MAPK signaling pathway were analyzed in gills and digestive glands. Tissue-specific responses were clearly investigated with gills showing more prompt responses and digestive glands showing higher tolerance to SMX. The histopathology showed that SMX triggered inflammatory damages in both tissues and quantitative analysis revealed more significant responses, suggesting its potential as a valuable health indicator. SMX activated expressions of p38, NFκB and p53 at transcriptional and (post-) translational levels, especially after exposed to low level SMX, evidenced by p38 coupled with NFκB/p53 regulation on immunity defense in mussels. Less induction of targeted molecules under severe SMX exposure indicated such signaling transduction may not be efficient enough and can result in inflammatory damages. Taken together, this study expanded the understanding of aquatic SMX induced health risk in marine mussels and the underlying regulation mechanism through p38 signaling transduction.

Veterinary antimicrobials in cattle feedlot environs and irrigation conveyances in a high-intensity agroecosystem in southern Alberta, Canada

The South Saskatchewan River Basin (SSRB) is considered one of the most intensively farmed regions in Canada, with high densities of livestock and expansive areas of irrigated cropland. We measured concentrations of seven veterinary antimicrobials (VAs) in 114 surface water samples from feedlot environs and 219 samples from irrigation conveyances in the SSRB. Overall, detection frequencies in feedlot environs were 100% for chlortetracycline (CTC) and tetracycline (TC), 94% for monensin (MON), 84% for tylosin (TYL), 72% for lincomycin (LIN), 66% for erythromycin (ERY), and 23% for sulfamethazine (SMZ). For irrigation conveyances, detection frequencies for CTC and TC remained high (94-100%), but dropped to 18% for ERY, 15% for TYL, 10% for MON, and 4% for SMZ. Lincomycin was not detected in irrigation conveyance water. Maximum concentrations of VAs ranged from 1384 µg L^-1 (TC) to 17 ng L^-1 (SMZ) in feedlot environs while those in irrigation conveyances were 155 ng L^-1 (TC) to 29 ng L^-1 (ERY). High detection frequencies and median concentrations of VAs in both feedlot environs and irrigation conveyances were associated with high amounts of precipitation. However, an irrigation district (ID) with high livestock density (Lethbridge Northern) did not exhibit higher concentrations of VAs compared to IDs with less livestock, while levels of VAs in irrigation conveyances were less influenced by the degree of surface runoff. The ubiquity of CTC and TC in our study is likely a reflection of its widespread use in intensive livestock operations. Additional investigation is required to link environmental concentrations of VAs with livestock densities and increase our understanding of potential antimicrobial resistance in high-intensity agroecosystems.

Antibiotic sulfadiazine degradation by persulfate oxidation: Intermediates dependence of ecotoxicity and the induction of antibiotic resistance genes

To preserve the water resources, this study has analyzed the ecotoxicity and antibiotic resistance genes (ARGs) induction capacity of sulfadiazine degradation intermediates resulting from persulfate activation oxidation enhanced by ultraviolet, ultrasound and microwave. The five degradation pathways caused by the contribution discrepancy of electron transfer and singlet oxygen (¹O₂) and variations in the ecotoxicity of different degradation products were analyzed. Microcosm experiment exhibited that the microbial community in actual water changed significantly with SDZ and degradation intermediates, in which the dominant genera were Aeromonas, Cupriavidus, Elizabethkingia and Achromobacter. Except for the selective pressure on bacteria, the degradation intermediates also exert a certain degree or even stronger induction on sulfonamide ARGs (sul4, sul1 and sul2) than SDZ. Furthermore, the potential hosts for sulfonamide ARGs were revealed by network analysis. These results provide a better understanding of antibiotics degradation mechanism and ARGs occurrence, which is useful for controlling the spread of ARGs.

Synergistic role of in-situ Zr-doping and cobalt oxide cocatalysts on photocatalytic bacterial inactivation and organic pollutants removal over template-free Fe2O3 nanorods

Herein, we synthesized in-situ Zr-doped Fe₂O₃ NRs photocatalyst by successive simple hydrothermal and air quenching methods. The synergistic roles of CoO_x (1 wt%) and Zr-doping on bacteria inactivation and model organic pollutants over Fe₂O₃ NRs photocatalyst were studied in detail. Initially, rod-like Zr ((0-8) %)-doped Fe₂O₃ NRs were produced via a hydrothermal method. CoO_x was loaded onto the Zr ((0-8) %)-doped Fe₂O₃ NRs) surface by a wet impregnation approach. The Zr-doping conditions and CoO_x loadings were judiciously optimized, and a highly photoactive CoO_x(1 wt%)/Zr(6%)-doped Fe₂O₃ NRs photocatalyst was developed. The CoO_x(1 wt%) loaded Zr(6%)-doped Fe₂O₃ NRs photocatalyst revealed 99.4% inactivation efficiency compared with (0, 4 and 8)% Zr-doped Fe₂O₃ NRs, respectively. After CoO_x(1 wt%)/Zr(6%)-doped Fe₂O₃ NRs photocatalyst treatment, Bio-TEM images of bacterial cells showed extensive morphological deviations in cell membranes, compared with the non-treated ones. Additionally, the optimum CoO_x(1 wt%)/Zr(6%)-doped Fe₂O₃ NRs photocatalyst exhibited 99.2% BPA and 98.3% orange II dye degradation after light radiation for 3 h. This work will provide a rapid method for the development of photostable catalyst materials for bacterial disinfection and organic degradation.

The potential ecological risk of veterinary pharmaceuticals from swine wastewater on freshwater aquatic environment

The impact of pharmaceutical residue transport in the aquatic ecosystem has become an increasing subject of environmental interest due to the inherent bioactivity of trace levels of antibiotics and the negative environmental and public health impact. In this study, three veterinary pharmaceuticals including tetracycline, ivermectin, and salicylic acid were investigated in a piggery effluent from Western Cape, South Africa. Three freshwater organisms' taxonomic groups (Pseudokirchneriella subcapitata, Daphnia magna, and Tetrahymena thermophila) were used to determine the ecological risk of different treated piggery effluent concentration range of 1%, 10%, and 20% and a cocktail mixture of veterinary pharmaceuticals of environmental concerns. The average concentration of veterinary pharmaceuticals was in the range of 47.35, 7.19, and 1.46 μg L^-1 for salicylic acid, chloro-tetracycline, and ivermectin, respectively. P. subcapitata exposed to 20% piggery wastewater effluent at 24- and 48-h EC₅₀ showed a toxicity value of 14.2% and 13.6% (v/v), respectively. The study established the ecological risk of the test compounds as low to medium risk for low-level dose and low concentrations of piggery effluent. The relative sensitivity ranking of the taxa drawn is microalgae > protozoa > Cladocera. The study results demonstrated that a high dose of piggery effluent and mixtures of veterinary pharmaceutical can pose a high risk in freshwater ecosystems. PRACTITIONER POINTS: Transport processes of veterinary antibiotics into the environment were investigated. Dilution effect of the veterinary pharmaceutical on the antibiotic levels exists. High dose of piggery effluent presented an ecological risk.

Effect of Different Lead and Cadmium Salts on the Photolytic Degradation of Two Typical Fluoroquinolones under Natural Sunlight Irradiation

This study investigated the effects of different lead and cadmium salts (Pb(NO₃)₂, Cd(NO₃)₂, PbCl₂, and CdCl₂) on the photolytic degradation of two typical fluoroquinolones (levofloxacin (LVF) and norfloxacin (NOR)) under natural sunlight irradiation. Their half-life time and photolytic kinetic constants (k) were calculated at different molar ratios. The results indicated that the photolytic degradation curves of LVF and NOR followed apparent first-order kinetics. After 42 days of sunlight irradiation, approximately 48.3-69.4% of NOR was decomposed when the initial concentration increased from 0.006 to 0.06 mmol/L. In comparison, only 9.8-43.4% of LVF was decomposed. The k of NOR ranged from 0.79 × 10^-3 to 1.30 × 10^-3 h^-1, and the k of LVF increased from 6.82 × 10^-4 to 1.61 × 10^-4 h^-1. Compared with the control, the Pb²⁺ and Cd²⁺ participation tended to enhance the LVF and NOR photodegradation. The effects of Cd²⁺ on the photodegradation efficiency were more significant than those of Pb²⁺. It was inferred that the presence of aqueous NO₃^- obviously suppressed the NOR degradation, but Cl^- had slight effects on these two fluoroquinolones' photodegradation. These results are of importance toward the understanding of the persistence of FQs under natural sunlight irradiation in surface waters.