Occurrences, transport drivers, and risk assessments of antibiotics in typical oasis surface and groundwater

Exacerbated anthropogenic water pollution under climate change and urbanization

Anthropogenic water pollution severely threatens human society worldwide, yet the water pollution induced by combined sewer overflow (CSO) remains unclear within climate change and urbanization. Hence, this study integrated the general circulation model (GCM) and shared socioeconomic pathway (SSP) projections with water quality modeling, to analyze spatiotemporal patterns and future trends of CSO-induced water pollution under changing environments. Results demonstrated that the given area (Dresden, Germany) encountered significant CSO-induced pollution, with 14,860 kg (95 % confidence interval, CI: 9,040-15,630 kg) of particulate matter (SS), organic compounds (COD, TN, TP), and pharmaceuticals (Carbamazepine, Gabapentin, Ciprofloxacin, Sulfamethoxazole) being discharged annually. Climate change and urbanization exacerbated the severity of CSO-induced pollution, causing the discharged pollutants to reach a maximum annual load of 34,900 kg (CI: 21,400-44,100 kg), with up to 82.19 % of organic compounds and 75.28 % of pharmaceuticals being discharged by the top 25 % of extreme CSOs. GIS-based spatial analysis indicated the regional heterogeneities of CSO-induced pollution, the high-frequency CSOs were predominantly located in highly-impervious areas, while the high-load discharges mainly occurred in densely-populated areas. Scenario analysis revealed stronger temporal variabilities of CSO-induced pollution in the future, with the seasonal anomalies of discharged loads ranging from -86.18 % to 76.89 %. In addition, pharmaceutical pollution exhibited significant uncertainties under changing environments, and the CI of discharged load expanded by up to 131.71 %. The methods and findings herein yielded further insights into water quality management in response to changing environments.

Contrastive cognition into the occurrence, source identification and risk assessment of antibiotics in various drinking water sources

Antibiotics are prevalent in aquatic ecosystems, particularly in critical drinking water sources, posing serious threats to human health and ecosystems. Focusing on rivers, lakes, reservoirs and groundwaters in Anhui Province (China), this study systematically investigated the occurrence, influencing factors and source apportionment of antibiotics and assessed their ecological and health risks. The results indicated that the total antibiotic concentrations ranged from 0.04 to 215.13 ng/L, and lincosamides and sulfonamides were the primary antibiotic groups, with concentrations of nd-167.00 ng/L and nd-47.38 ng/L, respectively. Specifically, lincomycin (nd-159.38 ng/L) and clindamycin (nd-100.45 ng/L) were the concentration of the two highest antibiotics, while sulfamethoxazole had the highest detection frequency (86.16 %). The total concentration of antibiotics in rivers was significantly higher than in lakes, reservoirs, and groundwaters, and the structural composition of antibiotics in groundwaters differed distinctly from that in other water sources. Nitrogen levels showed significant spatial correlation with antibiotic distribution, and anthropogenic activities may exacerbate antibiotic contamination. The study identified farmland drainage and aquaculture as the main sources of antibiotics in rivers and reservoirs, respectively, while livestock was the main source in lakes and groundwaters. The maximum ecological and human health risk quotient (8.83 and 0.32) of rivers was higher than that of other water sources. Antibiotics posing ecological risks included sulfamethoxazole, lincomycin, clindamycin, and clarithromycin, while tylosin and lincomycin exhibited potential threats to human health. Although the risks posed by individual antibiotics and their combined effects were within acceptable limits, the long-term exposure to low-dose antibiotics in drinking-water sources warrants close attention and further investigation.

Integrating microbial community dynamics and emerging contaminants (ECs) for precisely quantifying the sources in groundwater affected by livestock farming

Livestock farming is a major emission source of emerging contaminants (ECs); improper management of ECs could lead to severe groundwater pollution. However, research on accurately controlling the impact of large-scale livestock pollution in groundwater and quantifying sources of ECs pollution from livestock farming to formulating effective control measures is scarce. For the first time, the groundwater near four livestock farms (broiler, dairy, aquaculture, and pig farms) was selected as the research object to characterize the ECs, analyze the impact of ECs on microbial communities, and identify the pollution sources of livestock groundwater by the fast expectation-maximization of microbial source tracking (FEAST). Significant differences in the levels of antibiotics and hormones from four livestock farms led to changes in the groundwater microbial communities. The ECs improved the uniqueness of source biomarkers, providing better help for FEAST distinguishing livestock pollution sources at various groundwater mixing ratios. This study improved the accuracy of FEAST in investigating the pollution sources in groundwater and provided experimental evidence for accurate source tracking of ECs in groundwater in large-scale areas heavily polluted by livestock farming.

Vertical migration of antibiotics during rainfall throughout a year in long-term manure-fertilized soils differing in pH

The vertical migration behavior of antibiotics in long-term manure-fertilized soils during rainfall remains unclear. Here, we examined antibiotics in soil profiles (0-60 cm) and leachates following each rainfall event throughout a year for three soils (acidic, neutral, and calcareous) with a 13-year history of manure application. The total concentrations of all the antibiotics in the soil profile (11.04-190.32 μg/kg) and the yearly cumulative load of these antibiotics in the leachate (4070-6900 ng/m2) were significantly higher in the acidic and neutral soils than in the calcareous soil. Rainfall caused the migration of antibiotics (especially tetracyclines, quinolones, and sulfonamides) from soil to leachate, while the migration dynamics of some antibiotics differed among the three soil profiles. Random forest analysis revealed that precipitation, soil organic carbon content, pH, sand content, and the partition coefficient (Kow) of antibiotics were the key factors influencing the migration of antibiotics. Environmental risk assessment suggested that antibiotics in leachates pose low toxicity risks to aquatic organisms. Nevertheless, the vertical migration of some antibiotics (e.g., sulfachaloropyridazine and sufamerazine) was positively correlated with the dissemination of high-risk antibiotic resistance genes in leachates. This study advances our understanding of the precipitation-caused vertical migration of antibiotics in soil exposed to manure application, considering future increases in severe rainfall events.

Dealkylation metabolites of Atrazine: A previously Neglected Contributor to soybean phytotoxicity within atrazine residue

The phytotoxicity risks of atrazine to crops have received widespread attention, but the toxic effects of its metabolites on plants have been largely overlooked. In this study, the contributions and mechanisms underlying phytotoxicity of the atrazine and its metabolites (DEA and DIA) were systematically investigated in soybean seedlings. Two dealkylation metabolites DEA and DIA caused growth suppression, inhibited photosynthesis, activated the antioxidant system, and induced changes in chloroplast ultrastructure in soybean seedlings. Integrated Biological Response (IBR) analysis indicated that at equivalent environmentally relevant concentrations, the toxicity indices of DEA and DIA were 73.60% and 34.00% of atrazine, respectively. Molecular docking analysis revealed that both DEA and DIA exhibited high binding energies with Photosystem II D1 protein, with their potential target protein in soybean plants being consistent with that of atrazine. Metabolomic analysis further confirmed that the metabolites DEA and DIA disrupt key metabolic pathways, including alpha-linolenic acid metabolism, consistent with the mode of action of atrazine. These effects are associated with the inhibition of the photosynthetic electron transport chain and ROS accumulation. By calculating the environmental risk quotient, the risk of metabolites DEA to succeeding crops is likely to exceed that posed by the parent atrazine. These findings suggested that dealkylation metabolites of atrazine are overlooked contributors to soybean phytotoxicity in atrazine residue, and the risks posed by herbicide metabolites to crops need to be addressed.

Distribution and risk characteristics of antibiotics in China surface water from 2013 to 2024

The continuous release of large quantities of antibiotics into the aquatic environment has led to widespread water pollution in China. Therefore, this study investigated the antibiotic pollution levels and ecological risks of surface water in seven major Chinese watersheds based on research papers from 2013 to 2024. Measured concentrations and ecotoxicity data of sulfonamides (SAs), tetracyclines (TCs), fluoroquinolones (FQs), and macrolides (MLs) in the aquatic environments of China were collected and compiled. The environmental concentration and distribution characteristics of antibiotics in seven major watersheds were statistically analyzed to carry out the evaluation of multiple ecological risks of antibiotics in watersheds across the country, and at the same time, the traceability analysis of antibiotic pollution in different regions was carried out, which will provide a certain theoretical basis for the precise management of antibiotic pollution in the future. The results showed that the distribution and environmental risks of the four antibiotics in different watersheds varied greatly, with the Yangtze River Basin, the Huanghuai Basin, and the Pearl River Basin being affected by anthropogenic activities, economic development, and other factors, with a wider range of antibiotic sampling sites and higher detection concentrations, and with the Northwestern Basin, the Southwestern Basin, and the Songhua and Liaohe River Basins having an overall lower risk of antibiotics. FQs were detected at high concentrations in all the basins, mostly posing high risk to aquatic environments. SAs were the most frequently detected but had the lowest ecological risk. The results of the more refined risk assessment (joint probability curves, JPCs) were ranked in order of risk, with FQs ≥ TCs > MLs > SAs. These results can be used as a reference for integrated management and sustainability studies on basins across the country.

Effect of chlorination and ultraviolet on the adsorption of pefloxacin on polystyrene and polyvinyl chloride

During the water treatment process, chlorination and ultraviolet (UV) sterilization can modify microplastics (MPs) and alter their physicochemical properties, causing various changes between MPs and other pollutants. In this study, the impact of chlorination and UV modification on the physicochemical properties of polystyrene (PS) and polyvinyl chloride (PVC) were investigated, and the adsorption behavior of pefloxacin (PEF) before and after modification was examined. The effect of pH, ionic strength, dissolved organic matter, heavy metal ions and other water environmental conditions on adsorption behavior was revealed. The results showed that PS had a higher adsorption capacity of PEF than PVC, and the modification increased the presence of O-containing functional groups in the MPs, thereby enhancing the adsorption capacity of both materials. Chlorination had a more significant impact on the physicochemical properties of MPs compared to UV irradiation within the same time period, leading to better adsorption performance of chlorination. The optimal pH for adsorption was found to be 6, and NaCl, sodium alginate and Cu2+ would inhibit adsorption to varying degrees, among which the inhibition caused by pH was the strongest. Chlorination and UV modification would weaken the inhibitory effect of environmental factors on the adsorption of PEF by MPs. The main mechanisms of adsorption involved electrostatic interaction and hydrogen bonding. The study clarified the effects of modification on the physicochemical properties of MPs, providing reference for subsequent biotoxicity analysis and environmental protection studies.

A distributed and process-based model coupling water-sediment-antibiotic interactions to simulate dynamic source-transport-fate of antibiotics at catchment scale

A lack of hydro-biogeochemical models for catchment-scale antibiotic dynamics limits our mechanistic understanding of the transport and fate of antibiotics. This study addresses this gap by developing a distributed and process-based model that focuses on the complex water-sediment-antibiotic interactions. We applied the model to a typical agricultural catchment and selected tetracyclines (TCs) as the target antibiotics. Parameter sensitivity analysis demonstrated that source distribution, groundwater discharge, and water-soil/sediment partitioning were crucial processes. The multi-site performance evaluation generally proved the model's validity, though some overestimation of riverine concentration dynamics was observed. The grid-based distribution of the annual source inputs of the summation of the four TCs (∑4TCs) highly varied in space (μ = 3494.92 mg·ha-1·yr-1, σ = 4761.20 mg·ha-1·yr-1). About 99 % of the source inputs were retained in soil, with mixing layer as the largest reservoir and degradation as the primary loss pathway. Daily terrestrial discharged loading of ∑4TCs peaked with rainfall events. Surface runoff contributed more than 50 % of the terrestrial load of ∑4TCs in summer, while groundwater discharge dominated in other seasons. These results imply that the catchment-scale TCs dynamics are transport-limited rather than source-limited. Our model offers new insights into the high-resolution sources-transport-fate of antibiotics, aiding in developing strategies to mitigate antibiotic contamination.

Lanthanide-Porphyrin MOF as a Multifunctional Platform for Detection and Integrated Elimination of Cr(VI) and Ciprofloxacin

Environmental concerns are driving the development of eco-friendly and effective methods for contaminant monitoring and remediation. In this study, a lanthanide porphyrin-based MOF with dual fluorescence sensing and photocatalytic properties was synthesized and applied for the detection and combined removal of Cr(VI) and ciprofloxacin (CIP). Using different excitation wavelengths, the material exhibited selective detection of Cr(VI) via fluorescence quenching and CIP through fluorescence enhancement. The variation in color intensity of Tb-MOF on 3D EEM spectra enabled simultaneous detection of both contaminants. Additionally, Tb-MOF demonstrated a synergistic removal effect, achieving over 95% removal rates of Cr(VI) and CIP within 90 min, with consistent sensing and catalytic performance across four cycles. Mechanistic investigations revealed that (i) strong coordination between Tb3+ and CIP altered the surface potential of Tb-MOF, enhancing Cr(VI) adsorption; (ii) as an efficient electron acceptor, Cr(VI) promoted electron transfer and its reduction to Cr(III); and (iii) superoxide radicals generated via a type I mechanism played a key role in CIP degradation. This research underscores the potential of Tb-MOF as a multifunctional platform for simultaneous detection and synergistic remediation of mixed pollutants.

Occurrence, seasonal variation, and environmental risk of multiclass antibiotics in the urban surface water of the Buriganga River, Bangladesh

Owing to the extensive use of antibiotics in hospitals, animal husbandry, and various human activities, antibiotic contamination is becoming an increasing global concern, including in Bangladesh. In Bangladesh, the Buriganga River is heavily polluted with multiple antibiotics, which can lead to antibiotic resistance in bacteria. In this study, we performed the first investigation of seasonal variations in the occurrence and spatial distribution of 29 antibiotics in the Buriganga River, Bangladesh, from wet season (August 2019) and dry season (February 2020). We also evaluate the potential environmental and resistance risks related to antibiotic contamination. The concentrations of metronidazole (9.1-970 ng L-1), sulfadiazine (below the limit of detection ( Collapse

Key Words

• Antibiotics
• Bangladesh
• Occurrence
• Risk assessment
• River surface water

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MESH Headings

• Bangladesh
• Seasons
• Rivers/chemistry
• Anti-Bacterial Agents/analysis
• Water Pollutants, Chemical/analysis
• Environmental Monitoring
• Risk Assessment
• Cities

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Grants Collapse

Affiliation(s)

Umma Salma Graduate Division of Nutritional and Environmental Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan
Yuri Nishimura Graduate Division of Nutritional and Environmental Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan
Masahiro Tokumura Graduate Division of Nutritional and Environmental Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan.
Anwar Hossain Department of Fisheries, University of Dhaka, Dhaka, 1000, Bangladesh; Center for Marine Environmental Studies (CMES), Ehime University, Bunkyo-Cho 3, Matsuyama, Ehime, 790-8577, Japan
Kozo Watanabe Center for Marine Environmental Studies (CMES), Ehime University, Bunkyo-Cho 3, Matsuyama, Ehime, 790-8577, Japan
Kazushi Noro Graduate Division of Nutritional and Environmental Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan
Mohammad Raknuzzaman Department of Fisheries, University of Dhaka, Dhaka, 1000, Bangladesh
Takashi Amagai Graduate Division of Nutritional and Environmental Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan
Masakazu Makino Graduate Division of Nutritional and Environmental Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan.

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Collaborators Collapse

Development of pilot-scale plasma bubble reactors for efficient antibiotics removal in wastewater

Plasma bubble (PB) is a promising technology to control antibiotic wastewater pollution. However, the practical implementation of PB technology at the industrial-scale is still underdeveloped. In addition, the influence of different discharge modes for PB on wastewater treatment is largely unknown. This study designed pilot-scale PB reactors with different discharge modes to investigate the degradation effect of norfloxacin (NOR) and tetracycline (TC) in bulk tap water. Results indicate that the dielectric barrier discharge (DBD) mode with low average discharge power demonstrates superior degradation ability and higher production of O3(g) and .O2-(aq) compared to the spark mode which exhibits the high-intensity spark discharge in the tip area of the tube. After 40 min of treatment in a Double DBD reactor, 97.4% and 100% of NOR and TC are removed from 2 L tap water, attributed to the accumulation of antibiotic molecules by PBs and the in-situ generation of O3(g) and .O2-(aq) produced by plasma. Furthermore, a larger-scale PB reactor is developed by creating an array of four DBD reactors, effectively degrading 8 L mixed antibiotics solution. This study provides valuable insights for PB reactor design and the degradation performance of antibiotic wastewater, which will contribute to the further development of synergistic systems for plasma degradation.

More inputs of antibiotics into groundwater but less into rivers as a result of manure management in China

Antibiotics are extensively used in livestock production to prevent and treat diseases, but their environmental impact through contamination of rivers and groundwater is a growing concern. The specific antibiotics involved, their sources, and their geographic distribution remain inadequately documented, hindering effective mitigation strategies for river and groundwater pollution control caused by livestock production. Here we develope the spatially explicit MARINA-Antibiotics (China-1.0) model to estimate the flows of 24 antibiotics from seven livestock species into rivers and leaching into groundwater across 395 sub-basins in China, and examine changes between 2010 and 2020. We find that 8364 tonnes and 3436 tonnes of antibiotics entered rivers and groundwater nationwide in 2010 and 2020, respectively. Approximately 50-90% of these amounts originated from about 40% of the basin areas. Antibiotic inputs to rivers decreased by 59% from 2010 to 2020, largely due to reduced manure point sources. Conversely, antibiotic leaching into groundwater increased by 15%, primarily because of enhanced manure recycling practices. Pollution varied by antibiotic groups and livestock species: fluoroquinolones contributed approximately 55% to river pollution, mainly from pig, cattle, and chicken manure; sulfonamides accounted for over 90% of antibiotics in groundwater, predominantly from pig and sheep manure. While our findings support existing policies promoting manure recycling to mitigate river pollution in China, they highlight the need for greater attention to groundwater pollution. This aspect is essential to consider in developing and designing future reduction strategies for antibiotic pollution from livestock production.

Simulation and prediction of sulfamethazine migration, transformation and risk diffusion during cross-media infiltration from surface water to groundwater driven by dynamic water level: Machine learning coupled HYDRUS-GMS model

Seasonal water level fluctuations in rivers significantly influenced the cross-media migration, transformation, and risk diffusion of antibiotics from the vadose zone into groundwater. This study developed a coupled model integrating machine learning (ML) with HYDRUS-3D and GMS to accurately predict sulfamethazine migration under dynamic water levels. The predictive accuracy (E≥0.98) of this ML-HYDRUS-GMS model was enhanced by accounting for seasonal water level fluctuations and biogeochemical variability. Significant seasonal differences presented with sulfamethazine diffusion in the vadose zone with the migration rate decreased from 0.06 m/d to 0.02 m/d with the transition from wet to dry seasons. After 6 years of infiltration, it reached groundwater, where lateral migration rates, influenced by seasonal flow variations, were 0.12 m/d in the wet season and decreased to 0.07 m/d in the dry season, with a diffusion range extending to 217 m over 100 years. This discrepant continuous filtration of sulfamethazine and the succession of metabolic pathways induced toxicity range to expand by 65.6 m and the risk to increase to warning level. Sulfamethazine underwent oxidative breakdown in aerobic vadose zone conditions, while anaerobic groundwater conditions led to hydrogenation and reduction, increasing its migration distance.

Unraveling drivers of per- and polyfluoroalkyl substances (PFASs) occurrence and removal in leachate: Insights from disposal methods, geo-climate, and biodegradation

Leachate is a substantial reservoir of per- and polyfluoroalkyl substances (PFASs) within the environment. However, comprehensive information on the occurrence and fate of PFASs in leachate, particularly in semi-arid and moderate-elevation regions where PFASs may aggregate, is lacking. Here, 13 legacy PFASs were investigated in leachate from landfills and an incineration plant in such area. PFASs concentrations ranged from 6063 to 43,161 ng·L-1 in raw leachate, influenced by leachate origin, climate, wastewater disposal, and especially bacterial communities. Bacteroidetes and Firmicutes were enriched in raw leachate, while Proteobacteria dominated during leachate treatment processes, possibly due to PFASs selection pressure. In addition, top 20 biomarkers indicated the potential of these bacterial indicators for PFASs detection. Tracing analysis also suggested that PFASs in groundwater may have originated from leachate and effluent from wastewater treatment plants. PFASs levels in groundwater showed a significant correlation with the presence of Brevundimonas, Leptothrix, Malikia, and Sphaerotilus. The pathogenic bacterium Brevundimonas suggested potential human health risks, while Leptothrix, Malikia, and Sphaerotilus may serve as indicators of groundwater contamination. This study is believed to provide insights into how to prevent and control PFASs-related environmental pollution.

Transport, sources, and risks of particulate antibiotics in coastal environments: The crucial role of particles in mud coasts

Excessive antibiotic use has created environmental burdens. Coastal waters are often turbid, with suspended sediments (SPS) serving as carriers of antibiotics and intrinsically linked to particles in tidal flats. Although the distribution of antibiotics in water and sediments is well documented, environmental behaviors of particulate antibiotics remain limited. This study investigated 15 antibiotics in tidal sediments and coastal SPS, finding concentrations of 3.45-18.7 ng/g and 89.1-1.26 × 103 ng/g respectively, dominated by doxycycline (DXC) and oxytetracycline (OTC). Higher antibiotic proportion of SPS to water necessitated further research. Antibiotics were more evenly distributed in sediments. The primary source of antibiotics was rainfall runoff. Risk assessments highlighted antibiotics' risks to human health and ecosystems, especially fluoroquinolones. CODMn level in coastal water could predict antibiotic contamination in solids. This study distinguishes between dissolved and particulate antibiotics, elucidating their source, risk, and transport in turbid coastal environments, aiding in developing new seawater quality standards.

Driving mechanism of groundwater quality and probabilistic health risk quantification in the central Yinchuan Plain

The environmental changes from climatic, terrestrial and anthropogenic drivers can significantly influence the groundwater quality that may pose a threat to human health. However, the driving mechanism of groundwater quality and potential health risk still remains to be studied. In this paper, 165 groundwater samples were analyzed to evaluate the groundwater quality, driving mechanism, and probabilistic health risk in the central Yinchuan Plain by applying fuzzy comprehensive evaluation method (FCEM), redundance analysis (RDA) and Monte Carlo simulation. The results showed that hydrochemical evolution of groundwater were strongly influenced by water-rock interaction, evaporation and human activities. While 55.2% of groundwater samples reached the drinking water quality standard (Class I, II and III), 44.8% of samples exceeded the standard limits of Class III water quality (Class IV and V), indicating a high pollution level of groundwater. Mn, TDS, NH4+, NO3-, Fe, F-, NO2-, As were among major indicators that influence the groundwater quality due to the natural and anthropogenic processes. The RDA analysis revealed that climatic factors (PE: 10.9%, PRE: 1.1%), GE chemical properties (ORP: 20.7%, DO: 2.4%), hydrogeological factors (BD: 16.5%, K: 4.1%), and terrestrial factors (elevation: 1.2%; distanced: 5.6%, distancerl: 1.5%, NDVI: 1.2%) were identified as major driving factors influencing the groundwater quality in the study area. The HHRA suggested that TCR values of arsenic in infants, children and teens greatly exceeded the acceptable risk threshold of 1E-4, indicating a high cancer risk with a basic trend: infants > children > teens, while TCR values of adults were within the acceptable risk level. THI values of four age groups in the RME scenario were nearly ten times higher than those in the CTE scenario, displaying a great health effect on all age groups (HQ > 1). The present study provides novel insights into the driving mechanism of groundwater quality and potential health hazard in arid and semi-arid regions.

Source apportionment and specific-source-site risk of quinolone antibiotics for effluent-receiving urban rivers and groundwater in a city, China

There is a large surface-groundwater exchange downstream of wastewater treatment plants (WWTPs), and antibiotics upstream may influence sites downstream of rivers. Thus, samples from 9 effluent-receiving urban rivers (ERURs) and 12 groundwater sites were collected in Shijiazhuang City in December 2020 and April 2021. For ERURs, 8 out of 13 target quinolone antibiotics (QNs) were detected, and the total concentration of QNs in December and April were 100.6-4,398 ng/L and 8.02-2,476 ng/L, respectively. For groundwater, all target QNs were detected, and the total QNs concentration was 1.09-23.03 ng/L for December and 4.54-170.3 ng/L for April. The distribution of QNs was dissimilar between ERURs and groundwater. Most QN concentrations were weakly correlated with land use types in the system. The results of a positive matrix factorization model (PMF) indicated four potential sources of QNs in both ERURs and groundwater, and WWTP effluents were the main source of QNs. From December to April, the contribution of WWTP effluents and agricultural emissions increased, while livestock activities decreased. Singular value decomposition (SVD) results showed that the spatial variation of most QNs was mainly contributed by sites downstream (7.09%-88.86%) of ERURs. Then, a new method that combined the results of SVD and PMF was developed for a specific-source-site risk quotient (SRQ), and the SRQ for QNs was at high level, especially for the sites downstream of WWTPs. Regarding temporal variation, the SRQ for WWTP effluents, aquaculture, and agricultural emissions increased. Therefore, in order to control the antibiotic pollution, more attention should be paid to WWTP effluents, aquaculture, and agricultural emission sources for the benefit of sites downstream of WWTPs.

Environmental microbes alleviate antibiotic disturbance on plant endophytes in aquatic microcosms: Prospects for conferring fitness benefits

Antibiotic pollution in water environment is an emerging threat to plant health. Developing efficient strategies to reassemble the antibiotic-tolerating endophytes will confer fitness benefits on host plants to alleviate antibiotic stress. Here, introducing environmental microbes was proved as a promising approach to reshape the antibiotic-tolerating plant endophytes under antibiotic stress in aquatic microcosms. The introduction of environmental microbes effectively relieved antibiotic-driven perturbation on plant endophytes, with reduced changes in bacterial diversity and differential bacterial taxa and functional genes. Moreover, introducing environmental microbes facilitated the enrichment of endophytic bacterial genera and functional genes related to drug metabolism, which possessed the potentials to degrade antibiotics. In addition, environmental microbes boosted antibiotic-reshaped endophytes to form more stable bacterial networks for stronger antibiotic tolerance. In consequence, the decreased growth inhibition of antibiotics on host plants and enhanced antibiotic removal from microcosms were achieved by introducing environmental microbes. These findings pursue environmental microbes as practical resources to assist plants in reshaping the stress-alleviating endophytes, potentially improving plant tolerance to water pollution.

Complex impact of metals on the fate of disinfection by-products in drinking water pipelines: A systematic review

Metals in the drinking water distribution system (DWDS) play an important role on the fate of disinfection by-products (DBPs). They can increase the formation of DBPs through several mechanisms, such as enhancing the proportion of reactive halogen species (RHS), catalysing the reaction between natural organic matter (NOM) and RHS through complexation, or by increasing the conversion of NOM into DBP precursors. This review comprehensively summarizes these complex processes, focusing on the most important metals (copper, iron, manganese) in DWDS and their impact on various DBPs. It organizes the dispersed 'metals-DBPs' experimental results into an easily accessible content structure and presents their underlying common or unique mechanisms. Furthermore, the practically valuable application directions of these research findings were analysed, including the toxicity changes of DBPs in DWDS under the influence of metals and the potential enhancement of generalization in DBP model research by the introduction of metals. Overall, this review revealed that the metal environment within DWDS is a crucial factor influencing DBP levels in tap water.

Detection of Pharmaceutical Contamination in Amphipods of Lake Baikal by the HPLC-MS Method

Pollution by active ingredients is one of the most significant and widespread forms of pollution on Earth. Medicines can have a negative impact on ecosystems, and contamination can have unpredictable consequences. An urgent and unexplored task is to study the Lake Baikal ecosystem and its organisms for the presence of trace concentrations of active pharmaceutical ingredients. Our study aimed to conduct a qualitative analysis of active pharmaceutical ingredients, and quantitative analysis of ibuprofen in endemic amphipods of Lake Baikal, using methods of high-performance liquid chromatography and mass spectrometry (HPLC-MS). Acetylsalicylic acid (aspirin), ibuprofen, acetaminophen, azithromycin, dimetridazole, metronidazole, amikacin, spiramycin, and some tetracycline antibiotics were detected in the studied littoral amphipods. We also detected different annual loads of active pharmaceutical ingredients on amphipods. Using the multiple reaction monitoring (MRM) mode mentioned in GOST International Technical Standards, we detected molecules, fragmented as amikacin, chlortetracycline, doxycycline, oxytetracycline, dimetridazole, metronidazole and spiramycin. Thus, we first revealed that invertebrates of Lake Baikal can uptake pharmaceutical contaminants in the environment.

Occurrence and dissemination of antibiotics and antibiotic resistance in aquatic environment and its ecological implications: a review

The occurrence of antibiotics and antibiotic-resistant bacteria (ARBs), genes (ARGs), and mobile genetic elements (MGEs) in aquatic systems is growing global public health concern. These emerging micropollutants, stemming from improper wastewater treatment and disposal, highlight the complex and evolving nature of environmental pollution. Current literature reveals potential biases, such as a geographical focus on specific regions, leading to an insufficient understanding of the global distribution and dynamics of antibiotic resistance in aquatic systems. There is methodological inconsistency across studies, making it challenging to compare findings. Potential biases include sample collection inconsistencies, detection sensitivity variances, and data interpretation variability. Gaps in understanding include the need for comprehensive, standardized long-term monitoring programs, elucidating the environmental fate and transformation of antibiotics and resistance genes. This review summarizes current knowledge on the occurrence and dissemination of emerging micropollutants, their ecological impacts, and the global health implications of antimicrobial resistance. It highlights the need for interdisciplinary collaborations among researchers, policymakers, and stakeholders to address the challenges posed by antibiotic resistance in aquatic resistance in aquatic systems effectively. This review highlights widespread antibiotic and antibiotic resistance in aquatic environment, driven by human and agricultural activities. It underscores the ecological consequences, including disrupted microbial communities and altered ecosystem functions. The findings call for urgent measures to mitigate antibiotics pollution and manage antibiotic resistance spread in water bodies.

Research progress on the generation of NDMA by typical PPCPs in disinfection treatment of water environment in China: A review

The drugs and personal care products in water sources are potential threats to the ecological environment and drinking water quality. In recent years, the presence of PPCPs has been detected in multiple drinking water sources in China. PPCPs are usually stable and resistant to degradation in aquatic environments. During chlorination, chloramination, and ozonation disinfection processes, PPCPs can act as precursor substances to generate N-nitrosodimethylamine (NDMA) which is the most widely detected nitrosamine byproduct in drinking water. This review provides a comprehensive overview of the impact of PPCPs in China's water environment on the generation of NDMA during disinfection processes to better understand the correlation between PPCPs and NDMA generation. Chloramine is the most likely to form NDMA with different disinfection methods, so chloramine disinfection may be the main pathway for NDMA generation. Activated carbon adsorption and UV photolysis are widely used in the removal of NDMA and its precursor PPCPs, and biological treatment is found to be a low-cost and high removal rate method for controlling the generation of NDMA. However, there are still certain regional limitations in the investigation and research on PPCPs, and other nitrosamine by-products such as NMEA, NDEA and NDBA should also be studied to investigate the formation mechanism and removal methods.

Multi-medium residues and ecological risk of herbicides in a typical agricultural watershed of the Mollisols region, Northeast China

The widespread use of herbicides impacts non-target organisms, promotes weed resistance, posing a serious threat to the global goal of green production in agriculture. Although the herbicide residues have been widely reported in individual environmental medium, their presence across different media has received scant attention, particularly in Mollisols regions with intensive agricultural application of herbicides. A systematic investigation was conducted in this study to clarify the occurrence of herbicide residues in soil, surface water, sediments, and grains from a typical agricultural watershed in the Mollisols region of Northeast China. Concentrations of studied herbicides ranged from 0.30 to 463.49 μg/kg in soil, 0.31-29.73 μg/kg in sediments, 0.006-1.157 μg/L in water, and 0.32-2.83 μg/kg in grains. Among these, Clomazone was the most priority herbicide detected in soil, sediments, and water, and Pendimethalin in grains. Crop types significantly affected the residue levels of herbicides in grains. Clomazone posed high ecological risks in soil and water, with 86.4 % of water samples showing high risks from herbicide mixtures (RQ > 1). These findings aid in enhancing our comprehension of the pervasive occurrence and potential ecological risks of herbicides in different media within typical agricultural watersheds, providing detailed data to inform the development of targeted mitigation strategies.

Exploring the environmental pathways and challenges of fluoroquinolone antibiotics: A state-of-the-art review

Fluoroquinolone (FQ) antibiotics have become a subject of growing concern due to their increasing presence in the environment, particularly in the soil and groundwater. This review provides a comprehensive examination of the attributes, prevalence, ecotoxicity, and remediation approaches associated with FQs in environmental matrices. The paper discusses the physicochemical properties that influence the fate and transport of FQs in soil and groundwater, exploring the factors contributing to their prevalence in these environments. Furthermore, the ecotoxicological implications of FQ contamination in soil and aquatic ecosystems are reviewed, shedding light on the potential risks to environmental and human health. The latter part of the review is dedicated to an extensive analysis of remediation approaches, encompassing both in-situ and ex-situ methods employed to mitigate FQ contamination. The critical evaluation of these remediation strategies provides insights into their efficacy, limitations, and environmental implications. In this investigation, a correlation between FQ antibiotics and climate change is established, underlining its significance in addressing the Sustainable Development Goals (SDGs). The study further identifies and delineates multiple research gaps, proposing them as key areas for future investigational directions. Overall, this review aims to consolidate current knowledge on FQs in soil and groundwater, offering a valuable resource for researchers, policymakers, and practitioners engaged in environmental management and public health.

Occurrence of organophosphorus flame retardants in Xiangjiang River: Spatiotemporal variations, potential affecting factors, and source apportionment

The environmental occurrence of organophosphorus flame retardants (OPFRs) is receiving increasing attention. However, their distribution in the Xiangjiang River, an important tributary in the middle reaches of the Yangtze River, is still uncharacterized, and the potential factors influencing their distribution have not been adequately surveyed. In this study, the occurrence of OPFRs in the Xiangjiang River was comprehensively investigated from upstream to downstream seasonally. Fourteen OPFRs were detected in the sampling area, with a total concentration (∑OPFRs) ranging from 3.16 to 462 ng/L, among which tris(1-chloro-2-propyl) phosphate was identified as the primary pollutant (ND - 379 ng/L). Specifically, ∑OPFRs were significantly lower in the wet season than in the dry season, which may be due to the dilution effect of river flow and enhanced volatilization caused by higher water temperatures. Additionally, Changsha (during the dry season) and Zhuzhou (during the wet season) exhibited higher pollution levels than other cities. According to the Redundancy analysis, water quality parameters accounted for 35.7% of the variation in the occurrence of OPFRs, in which temperature, ammonia nitrogen content, dissolved oxygen, and chemical oxygen demand were identified as the potential influencing factors, accounting for 28.1%, 27.2%, 24.1%, and 11.5% of the total variation, respectively. The results of the Positive Matrix Factorization analysis revealed that transport and industrial emissions were the major sources of OPFRs in Xiangjiang River. In addition, there were no high-ecological risk cases for any individual OPFRs, although tris(2-ethylhexyl) phosphate and tributoxyethyl phosphate presented a low-to-medium risk level. And the results of mixture risk quotients indicated that medium-risk sites were concentrated in the Chang-Zhu-Tan region. This study enriches the global data of OPFRs pollution and contributes to the scientific management and control of pollution.

Physiological responses and removal mechanisms of ciprofloxacin in freshwater microalgae

Antibiotics, such as ciprofloxacin (CIP), are frequently detected in various environmental compartments, posing significant risks to ecosystems and human health. In this study, the physiological responses and elimination mechanisms of CIP in Chlorella sorokiniana and Scenedesmus dimorphus were determined. The exposure CIP had a minimal impact on the growth of microalgae, with maximum inhibit efficiency (IR) of 5.14% and 22.74 for C. sorokiniana and S. dimorphus, respectively. Notably, the photorespiration in S. dimorphus were enhanced. Both microalgae exhibited efficient CIP removal, predominantly through bioaccumulation and biodegradation processes. Intermediates involved in photolysis and biodegradation were analyzed through Liquid Chromatography High Resolution Mass Spectrometer (HPLC-MS/MS), providing insights into degradation pathways of CIP. Upregulation of key enzymes, such as dioxygenase, oxygenase and cytochrome P450, indicated their involvement in the biodegradation of CIP. These findings enhance our understanding of the physiological responses, removal mechanisms, and pathways of CIP in microalgae, facilitating the advancement of microalgae-based wastewater treatment approaches, particularly in antibiotic-contaminated environments.

Development of efficient and economic Bi2O3/BN/Co3O4 composite photocatalyst: Degradation mechanism, pathway and toxicity study of norfloxacin

The production of cheap, efficient, and stable photocatalysts for degrading antibiotic contaminants remains challenging. Herein, Bi2O3/boron nitride (BN)/Co3O4 ternary composites were synthesized using the impregnation method. The morphological characteristics, structural features, and photochemical properties of the prepared photocatalysts were investigated via X-ray diffraction, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, high-resolution transmission electron microscopy, and ultraviolet-visible (Vis) diffuse reflectance spectrum techniques. BN was used as a charge transfer bridge in the ternary composites, which afforded a heterojunction between the two semiconductors. The formation of the heterojunction substantially enhanced the charge separation and improved the photocatalyst performance. The degradation activity of the Bi2O3/BN/Co3O4 ternary composites against norfloxacin (NOR) under Vis light irradiation was investigated. The degradation rate of NOR using 5-wt% Bi2O3/BN/Co3O4 reached 98% in 180 min, indicating excellent photocatalytic performance. The ternary composites also exhibited high photostability with a degradation efficiency of 88.4% after five cycles. Hydroxyl radicals (•OH), superoxide radicals (•O2-), and holes (h+) played a synergistic role in the photocatalytic reaction, where h+ and •O2- were more important than •OH. Consequently, seven intermediates and major photocatalytic degradation pathways were identified. Toxicity experiments showed that the toxicity of the degradation solution to Chlorella pyrenoidosa decreased. Finally, the ecotoxicity of NOR and its intermediates were analyzed using the Toxicity Estimation Software Tool, with most intermediates exhibiting low toxicity.

One-step synthesis of iron and nitrogen co-doped porous biochar for efficient removal of tetracycline from water: Adsorption performance and fixed-bed column

Here, Fe/N co-doped porous biochars (FeNKBCs) were obtained by grinding corncob, CH3COOK, FeCl3·6H2O, and C3H6N6 via one-step synthesis and were applied to remove antibiotics from wastewater. Notably, CH3COOK had an excellent porous activation ability. The developed nanotubular structure of Fe1N2KBC had a high pore volume (Vtotal) (1.2131 cm3/g) and specific surface areas (SSA) (2083.54 m2/g), which showed outstanding sorption abilities for TC (764.35 mg/g), OTC (560.82 mg/g), SMX (291.45 mg/g), and SMT (354.65 mg/g). The adsorption process of TC was controlled by chemisorption. Moreover, Fe1N2KBC has an excellent dynamic adsorption performance (620.14 mg/g) in a fixed-bed column. The properties of SSA, Vtotal, and the content of graphite N and Fe-N were positively correlated with TC adsorption capacity. The high performance of TC removal was related to π-π stacking, pore-filling, hydrogen bond, and electrostatic interaction. Fe1N2KBC possessed stable sorption amounts in pH 2-12 and actual water, and well reuse performance. The results of this work present an effective preparation method of Fe/N porous biochar for TC-contaminated water remediation.

Maternal or Paternal Antibiotics? Intergenerational Transmission and Reproductive Toxicity in Zebrafish

Despite the known direct toxicity of various antibiotics to aquatic organisms, the potential chronic impact through intergenerational transmission on reproduction remains elusive. Here, we exposed zebrafish to a mixture of 15 commonly consumed antibiotics at environmentally relevant concentrations (1 and 100 μg L-1) with a cross-mating design. A high accumulation of antibiotics was detected in the ovary (up to 904.58 ng g-1) and testis (up to 1704.49 ng g-1) of F0 fish. The transmission of antibiotics from the F0 generation to the subsequent generation (F1 offspring) was confirmed with a transmission rate (ki) ranging from 0.11 to 2.32. The maternal transfer of antibiotics was significantly higher, relative to paternal transfer, due to a greater role of transmission through ovarian enrichment and oviposition compared to testis enrichment. There were similar impairments in reproductive and developmental indexes on F1 eggs found following both female and male parental exposure. Almost all antibiotics were eliminated in F2 eggs in comparison to F1 eggs. However, there were still reproductive and developmental toxic responses observed in F2 fish, suggesting that antibiotic concentration levels were not the only criterion for evaluating the toxic effects for each generation. These findings unveil the intergenerational transmission mechanism of antibiotics in fish models and underscore their potential and lasting impact in aquatic environments.

Synergistic effects of trace sulfadiazine and corrosion scales on disinfection by-product formation in bulk water of cast iron pipe

The effects of trace sulfadiazine (SDZ) and cast-iron corrosion scales on the disinfection by-product (DBP) formation in drinking water distribution systems (DWDSs) were investigated. The results show that under the synergistic effect of trace SDZ (10 μg/L) and magnetite (Fe3O4), higher DBP concentration occurred in the bulk water with the transmission and distribution of the drinking water. Microbial metabolism-related substances, one of the important DBP precursors, increased under the SDZ/Fe3O4 condition. It was found that Fe3O4 induced a faster microbial extracellular electron transport (EET) pathway, resulting in a higher microbial regrowth activity. On the other hand, the rate of chlorine consumption was quite high, and the enhanced microbial EET based on Fe3O4 eliminated the need for microorganisms to secrete excessive extracellular polymeric substances (EPS). More importantly, EPS could be continuously secreted due to the higher microbial activity. Finally, high reactivity between EPS and chlorine disinfectant resulted in the continuous formation of DBPs, higher chlorine consumption, and lower EPS content. Therefore, more attention should be paid to the trace antibiotics polluted water sources and cast-iron corrosion scale composition in the future. This study reveals the synergistic effects of trace antibiotics and corrosion scales on the DBP formation in DWDSs, which has important theoretical significance for the DBP control of tap water.

Synthesis of Metal-Organic Framework-Based ZIF-8@ZIF-67 Nanocomposites for Antibiotic Decomposition and Antibacterial Activities

Toxic antibiotic effluents and antibiotic-resistant bacteria constitute a threat to global health. So, scientists are investigating high-performance materials for antibiotic decomposition and antibacterial activities. In this novel research work, we have successfully designed ZIF-8@ZIF-67 nanocomposites via sol-gel and solvothermal approaches. The ZIF-8@ZIF-67 nanocomposite is characterized by various techniques that exhibit superior surface area enhancement, charge separation, and high light absorption performance. Yet, ZIF-8 has high adsorption rates and active sites, while ZIF-67 has larger pore volume and efficient adsorption and reaction capabilities, demonstrating that the ZIF-8@ZIF-67 nanocomposite outperforms pristine ZIF-8 and ZIF-67. Compared with pristine ZIF-8 and ZIF-67, the most active 6ZIF-67@ZIF-8 nanocomposite showed higher decomposition efficacy for ciprofloxacin (65%), levofloxacin (54%), and ofloxacin (48%). Scavenger experiments confirmed that •OH, •O2-, and h+ are the most active species for the decomposition of ciprofloxacin (CIP), levofloxacin (LF), and ofloxacin (OFX), respectively. In addition, the 6ZIF-67/ZIF-8 nanocomposite suggested its potential applications in Escherichia coli for growth inhibition zone, antibacterial activity, and decreased viability. Moreover, the stability test and decomposition pathway of CIP, LF, and OFX were also proposed. Finally, our study aims to enhance the efficiency and stability of ZIF-8@ZIF-67 nanocomposite and potentially enable its applications in antibiotic decomposition, antibacterial activities, and environmental remediation.

Occurrence, Distribution, and Trophic Transfer of Pharmaceuticals and Personal Care Products in the Bohai Sea

The ubiquitous presence of pharmaceuticals and personal care products (PPCPs) in environments has aroused global concerns; however, minimal information is available regarding their multimedia distribution, bioaccumulation, and trophic transfer in marine environments. Herein, we analyzed 77 representative PPCPs in samples of surface and bottom seawater, surface sediments, and benthic biota from the Bohai Sea. PPCPs were pervasively detected in seawater, sediments, and benthic biota, with antioxidants being the most abundant PPCPs. PPCP concentrations positively correlated between the surface and bottom water with a decreasing trend from the coast to the central oceans. Higher PPCP concentrations in sediment were found in the Yellow River estuary, and the variations in the physicochemical properties of PPCPs and sediment produced a different distribution pattern of PPCPs in sediment from seawater. The log Dow, but not log Kow, showed a linear and positive relationship with bioaccumulation and trophic magnification factors and a parabolic relationship with biota-sediment accumulation factors. The trophodynamics of miconazole and acetophenone are reported for the first time. This study provides novel insights into the multimedia distribution and biomagnification potential of PPCPs and suggests that log Dow is a better indicator of their bioaccumulation and trophic magnification.

Degradation of the antibiotic ciprofloxacin in urine by electrochemical oxidation with a DSA anode

Ciprofloxacin (CIP) is a commonly prescribed fluoroquinolone antibiotic that, even after uptake, remains unmetabolized to a significant extent-over 70%. Unmetabolized CIP is excreted through both urine and feces. This persistent compound manages to evade removal in municipal wastewater facilities, leading to its substantial accumulation in aquatic environments. This accumulation raises concerns about potential risks to the health of various living organisms. Herein, we present a study on the remediation of CIP in synthetic urine by electrochemical oxidation in an undivided cell with a DSA (Ti/IrO2) anode and a stainless-steel cathode. Physisorbed hydroxyl radical formed at the anode surface from water discharge and free chlorine generated from Cl- oxidation were the main oxidizing agents. The effect of pH and current density (j) on CIP degradation was examined, and its total removal was easily achieved at pH ≥ 7.0 and j ≥ 60 mA cm-2 due to the action of free chlorine. The CIP decay always followed a pseudo-first-order kinetics. The components of the synthetic urine were also oxidized. The main nitrogenated species released was NH3. A very small concentration of free chlorine was quantified at the end of the treatment, thus demonstrating the good performance of electrochemical oxidation and its effectiveness to destroy all the organic pollutants. The present study demonstrates the simultaneous oxidation of the organic components of urine during CIP degradation, thus showing a unique perspective for its electrochemical oxidation that enhances the environmental remediation strategies.

Occurrence, Bioaccumulation, Metabolism and Ecotoxicity of Fluoroquinolones in the Aquatic Environment: A Review

In recent years, there has been growing concern about antibiotic contamination in water bodies, particularly the widespread presence of fluoroquinolones (FQs), which pose a serious threat to ecosystems due to their extensive use and the phenomenon of "pseudo-persistence". This article provides a comprehensive review of the literature on FQs in water bodies, summarizing and analyzing contamination levels of FQs in global surface water over the past three years, as well as the bioaccumulation and metabolism patterns of FQs in aquatic organisms, their ecological toxicity, and the influencing factors. The results show that FQs contamination is widespread in surface water across the surveyed 32 countries, with ciprofloxacin and norfloxacin being the most heavy contaminants. Furthermore, contamination levels are generally higher in developing and developed countries. It has been observed that compound types, species, and environmental factors influence the bioaccumulation, metabolism, and toxicity of FQs in aquatic organisms. FQs tend to accumulate more in organisms with higher lipid content, and toxicity experiments have shown that FQs exhibit the highest toxicity to bacteria and the weakest toxicity to mollusk. This article summarizes and analyzes the current research status and shortcomings of FQs, providing guidance and theoretical support for future research directions.

Groundwater antibiotics contamination in an alluvial-pluvial fan, North China Plain: Occurrence, sources, and risk assessment

Antibiotics in groundwater have received widespread concern because high levels of them harm aquatic ecosystems and human health. This study aims to investigate the concentration, distribution, ecological and human health risks as well as potential sources of antibiotics in groundwater in the Hutuo River alluvial-pluvial fan, North China Plain. A total of 84 groundwater samples and nine surface water samples were collected, and 35 antibiotics were analyzed using ultra-performance liquid chromatography-tandem mass spectrometry. The results indicated that 12 antibiotics were detected in surface water with the total concentrations ranging from 5.33 ng/L to 64.73 ng/L. Macrolides were the primary category of antibiotics with a detection frequency of 77.8% (mean concentration: 9.14 ng/L). By contrast, in shallow granular aquifers (<150 m), 23 antibiotics were detected and the total concentrations of them ranged from below the method detection limit to 465.26 ng/L (detection frequency: 39.7%). Quinolones were the largest contributor of antibiotics with detection frequency and mean concentration of 32.1% and 12.66 ng/L, respectively. And ciprofloxacin and ofloxacin were the two preponderant individual antibiotics. The mean concentration of groundwater antibiotics in peri-urban areas was approximately 1.7-4.9 times that in other land use types. Livestock manure was the predominant source of antibiotics in groundwater. Erythromycin, sulfametoxydiazine, ofloxacin, and cinoxacin exhibited medium ecological risks to aquatic organisms. All antibiotics posed no risks to human health. The findings of this study provide valuable insights into the occurrence and management of antibiotic contamination in the groundwater in the Hutuo River alluvial-pluvial fan.

Effects of Antibiotic Resistance Genes and Antibiotics on the Transport and Deposition Behaviors of Bacteria in Porous Media

Antibiotics present in the natural environment would induce the generation of antibiotic-resistant bacteria (ARB), causing great environmental risks. The effects of antibiotic resistance genes (ARGs) and antibiotics on bacterial transport/deposition in porous media yet are unclear. By using E. coli without ARGs as antibiotic-susceptible bacteria (ASB) and their corresponding isogenic mutants with ARGs in plasmids as ARB, the effects of ARGs and antibiotics on bacterial transport in porous media were examined under different conditions (1-4 m/d flow rates and 5-100 mM NaCl solutions). The transport behaviors of ARB were comparable with those of ASB under antibiotic-free conditions, indicating that ARGs present within cells had negligible influence on bacterial transport in antibiotic-free solutions. Interestingly, antibiotics (5-1000 μg/L gentamicin) present in solutions increased the transport of both ARB and ASB with more significant enhancement for ASB. This changed bacterial transport induced by antibiotics held true in solution with humic acid, in river water and groundwater samples. Antibiotics enhanced the transport of ARB and ASB in porous media via different mechanisms (ARB: competition of deposition sites; ASB: enhanced motility and chemotaxis effects). Clearly, since ASB are likely to escape sites containing antibiotics, these locations are more likely to accumulate ARB and their environmental risks would increase.

Occurrence and risk levels of antibiotic pollution in the coastal waters of eastern China

In order to preliminarily explore the distribution of antibiotic pollution in the coastal waters of eastern China, the concentrations of 13 antibiotics in 5 representative coastal rivers in Jiangsu and 21 sampling sites in the coastal waters of Jiangsu were analyzed. The total antibiotic concentrations in the 5 rivers ranged from 33.14 to 417.78 ng L^-1, and the total antibiotic concentrations in the 21 sampling sites ranged from 0.90 to 86.33 ng L^-1. Macrolides exhibited the highest total concentration and the maximum detection frequency in both coastal rivers and the coastal waters. The concentrations of antibiotics in a sampling site decreased as the distance of the sampling site from the coastline increased, indicating that river inputs are important sources of antibiotic pollution in the coastal waters of Jiangsu. The detection frequencies of roxithromycin, lincomycin, azithromycin, and sulfamethoxazole in the rivers and sampling sites were above 70%. Correlation analysis showed that the concentrations of antibiotics were positively correlated with the levels of chemical oxygen demand, total phosphorus, and total nitrogen. Risk assessments revealed that roxithromycin and ofloxacin posed medium ecological and resistance risks, respectively, to the most sensitive aquatic organisms in the coastal waters of Jiangsu. The results of this study highlight the significance of monitoring and controlling the concentrations of antibiotic contaminants in the coastal waters of Jiangsu.

Microscopic insights into the variations of antibiotics sorption to clay minerals

Understanding the adsorption behavior of antibiotic molecules on minerals is crucial for determining the environmental fate and transport of antibiotics in soils and waters. However, the microscopic mechanisms that govern the adsorption of common antibiotics, such as the molecular orientation during the adsorption process and the conformation of sorbate species, are not well understood. To address this gap, we conducted a series of molecular dynamics (MD) simulations and thermodynamics analyses to investigate the adsorption of two typical antibiotics, tetracycline (TET) and sulfathiazole (ST), on the surface of montmorillonite. The simulation results indicated that the adsorption free energy ranged from - 23 to - 32 kJ·mol^-1, and - 9 to - 18 kJ·mol^-1 for TET and ST, respectively, which was consistent with the measured difference of sorption coefficient (K_d) for TET-montmorillonite of 11.7 L·g^-1 and ST-montmorillonite of 0.014 L·g^-1. The simulations also found that TET was adsorbed through dimethylamino groups (85% in probability) with a molecular conformation vertical to the montmorillonite's surface, while ST was adsorbed through sulfonyl amide group (95% in probability) with vertical, tilted and parallel conformations on the surface. The results confirmed that molecular spatial orientations could affect the adsorption capacity between antibiotics and minerals. Overall, the microscopic adsorption mechanisms revealed in this study provide critical insights into the complexities of antibiotics adsorption to soil and facilitate the prediction of adsorption capacity of antibiotics on minerals and their environmental transport and fate. This study contributes to our understanding of the environmental impacts of antibiotic usage and highlights the importance of considering molecular-level processes when assessing the fate and transport of antibiotics in the environment.

A novel heterogeneous catalytic system (AC/ZVI/CaO2) promotes simultaneous removal of phosphate and sulfamethazine: Performance, mechanism and application feasibility verification

The eutrophication and pharmaceutical residue are the key issues to the treatment of rural non-point source pollution, concerning risks to aquatic ecosystems and human health. In this study, a novel activated carbon/zero-valent iron/calcium peroxide (AC/ZVI/CaO₂) catalytic system was constructed to remove simultaneously typical rural non-point source pollutants: phosphate and sulfamethazine (SMZ). The optimal mass ratio of the system was determined as 20% AC, 48% ZVI and 32% CaO₂. It was shown that the removal efficiency of phosphorus (P) and SMZ exceeded 65% and 40% in pH 2-11, respectively. It worked well in the presence of typical anions and humic acid. The mechanistic analyses for P removal indicated that AC/ZVI/CaO₂ system can effectively load P by the formation of crystalline state Ca-P species and Fe-P/Ca-P amorphous state coprecipitates under neutral and acidic conditions, respectively. The presence of AC in AC/ZVI/CaO₂ system could form iron-carbon micro-electrolysis process for accelerating Fenton reaction in acidic environment. And AC also can produce reactive oxygen species for the SMZ degradation by relying on persistent free radicals/graphitic carbon catalysis under environmental condition. In addition, we developed a low-impact development stormwater filter for application feasibility verification of the system. Feasibility analysis showed that the system could save up to ∼50% cost in contrast with the price of Phoslock (a commercial P load product) and presented advantages of non-toxicity, long-acting, stability and the potential to promote biodegradation by provision of aerobic environment.

Occurrence and Distribution of Antibiotics in the Water, Sediment, and Biota of Freshwater and Marine Environments: A Review

Antibiotics, as pollutants of emerging concern, can enter marine environments, rivers, and lakes and endanger ecology and human health. The purpose of this study was to review the studies conducted on the presence of antibiotics in water, sediments, and organisms in aquatic environments (i.e., seas, rivers, and lakes). Most of the reviewed studies were conducted in 2018 (15%) and 2014 (11%). Antibiotics were reported in aqueous media at a concentration of <1 ng/L−100 μg/L. The results showed that the highest number of works were conducted in the Asian continent (seas: 74%, rivers: 78%, lakes: 87%, living organisms: 100%). The highest concentration of antibiotics in water and sea sediments, with a frequency of 49%, was related to fluoroquinolones. According to the results, the highest amounts of antibiotics in water and sediment were reported as 460 ng/L and 406 ng/g, respectively. In rivers, sulfonamides had the highest abundance (30%). Fluoroquinolones (with an abundance of 34%) had the highest concentration in lakes. Moreover, the highest concentration of fluoroquinolones in living organisms was reported at 68,000 ng/g, with a frequency of 39%. According to the obtained results, it can be concluded that sulfonamides and fluoroquinolones are among the most dangerous antibiotics due to their high concentrations in the environment. This review provides timely information regarding the presence of antibiotics in different aquatic environments, which can be helpful for estimating ecological risks, contamination levels, and their management.