Occurrence of antibiotics in water, sediments, aquatic plants, and animals from Baiyangdian Lake in North China

Effect of antibiotics on diverse aquatic plants in aquatic ecosystems

The widespread presence of antibiotics in aquatic ecosystems, mainly due to their use in medicine and veterinary practices, poses a significant environmental challenge. Aquatic plants play a vital role in maintaining ecosystem stability, but their responses to antibiotics vary by species, influenced by differences in their traits and interactions with environmental factors. However, the specific ways antibiotics affect these plants remain poorly understood. In this study, we conducted a meta-analysis of 167 peer-reviewed studies to investigate the mechanisms of antibiotic uptake and their effects on different types of aquatic plants-submerged, emergent, and floating. Our analysis shows that antibiotics, particularly common ones like sulfonamides, tetracyclines, and quinolones, impact aquatic plants through multiple pathways. Submerged and floating plants often face widespread, direct exposure, resulting in "full-coverage" impacts, while emergent plants experience mixed exposure patterns, affecting both submerged and aerial parts and leading to "partial-coverage" impacts. These findings provide a foundation for phytoremediation strategies, enabling the rational selection and management of aquatic plant types to mitigate antibiotic pollution. Our study underscores the ecological risks posed by antibiotic contamination in aquatic ecosystems and offers a theoretical framework for developing effective restoration strategies.

Environmental gradient changes shape multi-scale food web structures: Impact on antibiotics trophic transfer in a lake ecosystem

Environmental change can alter the multi-scale foodweb structure, thereby impacting the pollutants trophic transfer in aquatic ecosystems. However, a quantitative understanding of how environmental gradient changes affect pollutant trophic transfer in natural lake ecosystems remains limited. This study investigated temporal variations in environment change index (ECi), multi-scale foodweb structure, and trophic transfer of quinolones antibiotics (QNs) in Baiyangdian Lake, Northern China, from 2018 to 2023. Our results demonstrated that the interaction strength (IS) in detritus (DIS) and macrophyte (MIS) in 2023 were significantly lower than those in 2018, and diversity indices exhibited significant temporal differences between 2018 and 2023. ECi was significantly correlated with DIS/MIS between species at the population scale and with diversity indices (DH and H') at the ecosystem scale. The trophic magnification factors (TMFs) of QNs have higher values in 2023 compared to 2018, showing significant temporal differences. Through structural equation model, the results showed ECi directly impacted DIS, which in turn affected SEAc and H', while indirectly influencing TMFs. The TMFs of QNs was mainly regulated by environmental factors. These findings highlighted the influencing mechanism through multi-scale foodweb structures regulate pollutant trophic transfer under environmental change in natural lake.

Exploring the mechanism of PPCPs on human metabolic diseases based on network toxicology and molecular docking

This research endeavor seeks to delve into the potential mechanisms by which pharmaceutical and personal care products (PPCPs), recognized as emerging pollutants, could contribute to the human metabolic disorders and then trigger metabolic diseases. Therefore, we have selected lipid and atherosclerosis, Alzheimer's disease, and type Ⅱ diabetes mellitus as representative metabolic diseases, aiming to systematically explore the critical molecular pathways that may be disrupted by PPCPs for the metabolic disease development. By employing advanced network toxicology and molecular docking techniques, we have successfully elucidated the molecular mechanisms that trigger the three diseases. We pinpointed the potential targets associated with the disease by leveraging databases including PubChem, ADEMTlab2.0, SwissADME, and GeneCards. We further employed STRING analysis and Cytoscape software to pinpoint the core targets that were most significantly associated with these metabolic diseases. In addition, enrichment analysis of these core targets was conducted using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways within the David database. To obtain the structural aspects of the target proteins, we also employed AlphaFold 3 for protein structure prediction. Finally, we validated the binding affinity of PPCPs to these target proteins using molecular docking with AutoDock Vina. Our findings suggested that PPCPs could potentially trigger metabolic diseases by modulating the expression of microRNAs, influencing cellular apoptosis and proliferation, and affecting signal transduction pathways. Interestingly, we also found the correlations among lipid and atherosclerosis, Alzheimer's disease, and type Ⅱ diabetes mellitus. Taken together, our study provides innovative insights into both the mechanisms of how environmental pollutants trigger human diseases and revealing the correlations among different diseases, thereby laying a theoretical foundation for disease prevention and treatment.

Aging-mediated selective adsorption of antibiotics by tire wear particles: Hydrophobic and electrostatic interactions effects

Tire wear particles (TWPs), as a prevalent form of microplastic pollution in aquatic environments, have been shown to adsorb antibiotics, potentially exacerbating their toxic effects. This study provides a comprehensive analysis of the adsorption of ofloxacin (OFL), ciprofloxacin (CIP), sulfadiazine (SDZ), and tetracycline (TC) on TWPs that have undergone various aging processes, including cyclic freeze-thaw and ozone aging. We observed a significant increase in the specific surface area (SBET) of TWPs after aging, from an initial 2.81 ± 0.29 to 6.63 ± 0.16 m2/g for ozone-aged TWPs. This enhancement in surface area and pore volume led to a respective 1.36-fold and 28-fold increase in adsorption capacity for OFL and CIP, highlighting the substantial impact of aging on TWPs' adsorptive properties. Conversely, the adsorption of SDZ and TC was reduced post-aging, suggesting a complex interaction between antibiotic physicochemical properties and TWPs' surface characteristics. The pseudo-second-order model, indicating chemisorption interactions, effectively described the adsorption kinetics, with the Freundlich isotherm model capturing the adsorption behavior more accurately than the Langmuir model. Our findings underscore the critical role of hydrophobic and electrostatic interactions in the adsorption process, particularly for SDZ and TC. This study's results offer crucial insights into the environmental implications of TWPs, emphasizing the need for further research on their role in the transport and fate of antibiotics in aquatic ecosystems.

Occurrence and ecological risks of antibiotics and antiparasitics in surface water in urban lakes in Hanoi city, Vietnam

The presence of antibiotics in the environment is of significant concern due to their adverse effects on aquatic ecosystems. This study provides an assessment of potential ecological risks (RQ) associated with the concentrations of eight antibiotics and antiparasitics (amoxicillin-AMO, azithromycin-AZI, ciprofloxacine-CIP, ofloxacine-OFL, oxfendazole-OXF, lincomycin-LIN, sulfacetamide-SCE and sulfamethoxazole-SME) in the surface water of 13 urban lakes in Hanoi city, Vietnam during the period 2021-2023. The findings revealed considerable variations in the total concentrations of these 8 substances (TAB), ranging from below the method detection limit (< MDL) to 2240 ng L-1 with an average of 330.4 ng L-1. Among the 8 antibiotics and antiparasitics examined, OXF, AMO, and SCE were undetectable, while the others were present at a range of concentrations (in ng L-1): OFL: 129 (< MDL-1530); CIP: 87.1 (< MDL-608); LIN: 72.7 (< MDL-676); SME: 41.5 (< MDL-504); AZI: 0.03 (< MDL-1). The calculated RQ values for these antibiotics in the Hanoi lakes indicated a high ecological risk for OFL and CIP to bacteria, a medium to high risk for SME for phytoplankton, a high risk for LIN to phytoplankton, while the risk for invertebrates was deemed negligible for all antibiotics across all lakes. The strong, positive correlation between TAB concentrations and different microbial and environmental variables (Escherichia coli, ammonium, phosphate, and chemical oxygen demand) suggests that untreated domestic wastewater is the primary pollution source in these Hanoi lakes. These results should be used to raise public awareness and to encourage the implementation of strategies targeted at managing antibiotic use. They also underscore the need to reduce inputs of untreated, antibiotic-containing wastewater into urban lakes, such as those in Hanoi and advocate for the establishment of national limits for antibiotic concentrations in surface water.

Microplastics enhance the adsorption capacity of zinc oxide nanoparticles: Interactive mechanisms and influence factors

Microplastics (MPs) are of particular concern due to their ubiquitous occurrence and propensity to interact and concentrate various waterborne contaminants from aqueous surroundings. Studies on the interaction and joint toxicity of MPs on engineered nanoparticles (ENPs) are exhaustive, but limited research on the effect of MPs on the properties of ENPs in multi-solute systems. Here, the effect of MPs on adsorption ability of ENPs to antibiotics was investigated for the first time. The results demonstrated that MPs enhanced the adsorption affinity of ENPs to antibiotics and MPs before and after aging showed different effects on ENPs. Aged polyamide prevented aggregation of ZnONPs by introducing negative charges, whereas virgin polyamide affected ZnONPs with the help of electrostatic attraction. FT-IR and XPS analyses were used to probe the physicochemical interactions between ENPs and MPs. The results showed no chemical interaction and electrostatic interaction was the dominant force between them. Furthermore, the adsorption rate of antibiotics positively correlated with pH and humic acid but exhibited a negative correlation with ionic strength. Our study highlights that ENPs are highly capable of accumulating and transporting antibiotics in the presence of MPs, which could result in a widespread distribution of antibiotics and an expansion of their environmental risks and toxic effects on biota. It also improves our understanding of the mutual interaction of various co-existing contaminants in aqueous environments.

A novel enrofloxacin-degrading fungus, Humicola sp. KC0924g, isolated from the rhizosphere sediment of the submerged macrophyte Vallisneria spiralis L

A novel enrofloxacin-degrading fungus was isolated from a rhizosphere sediment of the submerged macrophyte Vallisneria spiralis L.. The isolate, designated KC0924g, was identified as a member of the genus Humicola based on morphological characteristics and tandem conserved sequence analysis. The optimal temperature and pH for enrofloxacin degradation by strain KC0924g were 28 °C and 9.0, respectively. Under such condition, 98.2% of enrofloxacin with an initial concentration of 1 mg L-1 was degraded after 72 h of incubation, with nine possible degradation products identified. Four different metabolic pathways were proposed, which were initiated by cleavage of the piperazine moiety, hydroxylation of the aromatic ring, oxidative decarboxylation, or defluorination. In addition to enrofloxacin, strain KC0924g also degraded other fluoroquinolone antibiotics (ciprofloxacin, norfloxacin, and ofloxacin), malachite green (an illegal additive in aquaculture), and leucomalachite green. Pretreatment of cells of strain KC0924g with Cu2+ accelerated ENR degradation. Furthermore, it was speculated that a flavin-dependent monooxygenase was involved in ENR degradation, based on the increased transcriptional levels of these two genes after Cu2+ induction. This work enriches strain resources for enrofloxacin remediation and, more importantly, would facilitate studies on the molecular mechanism of ENR degradation with degradation-related transcriptome available.

Occurrence and risk assessment of quinolones and sulfonamides in freshwater aquaculture ponds in Northeast Zhejiang, China

Antibiotics play an essential role in the aquaculture industry, but their overuse and weak degradability inevitably lead to light to severe residues in natural and aquaculture environments. Most studies were interested in the occurrence, distribution, and ecological risks of a limited number of antibiotics in natural environments (rivers, lakes, and coastal regions) with a minor focus on antibiotic presence in either water, sediments, or organisms in aquaculture environments located in specific regions. In this study, we conducted a comprehensive investigation into the occurrence and distribution of up to 32 antibiotics [including 15 quinolones (QNs) and 17 sulfonamides (SAs)] in organisms and their corresponding environmental matrices from 26 freshwater aquaculture ponds in Northeast Zhejiang, China. A total of 13, 9, 7, and 7 antibiotics were detected in pond water, sediments, feeds, and aquaculture organisms, respectively, with concentration ranges of 0.6-92.2 ng/L, 0.4-1169.3 ng/g dw, Collapse

Key Words

• Antibiotics
• Contamination
• Cultured ponds
• Ecological risk
• Farming
• Health risk

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MESH Headings

• Water Pollutants, Chemical/analysis
• Aquaculture
• Sulfonamides/analysis
• China
• Quinolones/analysis
• Risk Assessment
• Environmental Monitoring
• Ponds/chemistry
• Anti-Bacterial Agents/analysis
• Animals
• Fresh Water/chemistry

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Affiliation(s)

Hongmei Hu Key Laboratory of Sustainable Utilization of Technology Research for Fisheries Resources of Zhejiang Province, Zhejiang Marine Fisheries Research Institute, Zhoushan 316021, PR China
Mengyu Qi Key Laboratory of Sustainable Utilization of Technology Research for Fisheries Resources of Zhejiang Province, Zhejiang Marine Fisheries Research Institute, Zhoushan 316021, PR China
Pengfei He Key Laboratory of Sustainable Utilization of Technology Research for Fisheries Resources of Zhejiang Province, Zhejiang Marine Fisheries Research Institute, Zhoushan 316021, PR China
Xuechang Chen Key Laboratory of Sustainable Utilization of Technology Research for Fisheries Resources of Zhejiang Province, Zhejiang Marine Fisheries Research Institute, Zhoushan 316021, PR China
Zhenhua Li Key Laboratory of Sustainable Utilization of Technology Research for Fisheries Resources of Zhejiang Province, Zhejiang Marine Fisheries Research Institute, Zhoushan 316021, PR China.
Heyong Cheng College of Material Chemistry and Chemical Engineering, Key Laboratory of Organosilicon Chemistry and Material Technology, Ministry of Education, Hangzhou Normal University, Hangzhou 311121, PR China.

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Spatial and temporal distribution and ecological risk assessment of typical antibiotics in natural and wastewater of Jinjiang River Basin

Antibiotics are widely used in human medical, livestock, and aquaculture fields. Most antibiotics are water-soluble and cannot be fully absorbed by humans or animals. If feces or wastewater containing antibiotics are improperly treated or discharged directly into surface water or groundwater, it will undoubtedly have an impact on aquatic organisms. The Ganjiang River is the largest river in Jiangxi Province and the largest tributary of Poyang Lake Basin. Jinjiang River, a tributary of Ganjiang River, is a typical livestock and poultry breeding area in the Poyang Lake Basin, along which many townships and counties are distributed. Gao'an and Shanggao counties are important agricultural and animal husbandry production areas in Jiangxi Province. In this paper, automatic solid phase extraction-ultra high performance liquid chromatography-mass spectrometry (SPE-UPLC-MS/MS) technology was used to simultaneously detect 27 antibiotics in 5 categories of macrolides, tetracyclines, quinolones, nitroimidazoles and sulfonamides in water. Based on this method, the concentrations and distributions of these antibiotics were analyzed. Ecological risk assessment of the Jinjiang River Basin was conducted using the ecological risk quotient method, aiming to supplement antibiotic data in the Jinjiang River Basin and provide scientific basis for local ecological environment management. The research results indicate that from 2019 to 2021, two years later, there was an increase in the use of Sulfadiazine and Roxithromycin in the Jinjiang River Basin, while the usage of Ciprofloxacin and Oxytetracycline was relatively low. In 2021, out of the 27 antibiotics, 24 were detected in surface water, 20 in groundwater, and all in wastewater. Among them, Sulfamethoxazole was the most widely used antibiotic, primarily in livestock and poultry farming. Gao'an City, a key breeding area in the Jinjiang River Basin, exhibited the highest concentration of Sulfamethoxazole at 409.96 ng·L-1, which far exceeds other antibiotics and warrants significant attention. A comparison of surface water concentrations between the Jinjiang River and 12 other regions revealed higher overall pollution levels of Roxithromycin and Sulfamethoxazole. Furthermore, according to the ecological risk assessment results, only Sulfamethoxazole poses a moderate risk to aquatic organisms.

Occurrence, distribution, and correlation of antibiotics in the aquatic ecosystem of Poyang Lake Basin, China

The widespread existence and persistence of antibiotics in the aquatic environment, and their extensive ecological risks, have attracted considerable attention. The objective of this study was to evaluate the occurrence and distribution of 25 antibiotics in environmental and biological samples from Poyang Lake Basin in China. SPE-HPLC-MS/MS was used to quantify the concentrations in different matrices. The total concentrations ranged from 144 to 933 ng/L in the water and 346 to 1154 ng/g in the sediment. In the spatial distribution analysis of this basin, the concentrations in the Ganjiang River were generally higher than those in Poyang Lake. The seasonal distribution in the wet and dry seasons showed comparatively higher concentrations during the dry season than the wet season. Additionally, antibiotics were found in various hydrophytes and animals, and the bioconcentration factor values followed the order: emergent plants > floating plants > submerged plants and benthic organisms > ducks > fish. Moreover, correlations among different matrices showed that antibiotics in viviparid snails were significantly positively correlated with those in ducks, and negatively correlated with those in carps, indicating the transmission relationship through the food chain. The results showed the trophic transfer of antibiotics in the food web and their potential environmental impacts on Poyang Lake Basin need constant attention.

Simultaneous electrochemical removal of three microcystin congeners and sulfamethoxazole in natural water

Microcystins (MCs), frequently detected in freshwater ecosystems, have raised significant human health and ecological concerns. New approaches are being developed to control and remove MCs. In this study, we examined factors influencing the efficacy of electrochemical oxidation as a means of control. Anode material (Pt/Ti, Ta2O5-IrO2/Ti, SnO2-SbO2/Ti, boron-doped diamond (BDD/Si), anode surface area ratios and solution volumes, initial pollutant concentrations, and the co-existing antibiotic sulfamethoxazole (SMX) were investigated. MCs and SMX were dissolved in filtered Taihu Lake water to simulate the natural aquatic environment. The results showed that non-active anodes, lower initial concentration of MC, larger surface area ratio of cathode to anode, and smaller ratio of reaction solution volume to anode surface area could promote the degradation target pollutants. Under optimal conditions in this study, the degradation rates of MC-LR, MC-YR, MC-RR, and SMX each reached more than 90% within 6 h, and the removal efficiency of MC-YR was the highest among three congeners. The effect of SMX on the degradation of MC congeners depended mainly on their concentration differences, such that when the initial concentration of SMX was one to two orders of magnitude lower than microcystin, the presence of SMX would promote the degradation of MCs. In contrast, when the initial concentration of SMX was higher than that of microcystin by approximately an order of magnitude, sulfamethoxazole would inhibit the degradation of MCs by between 4.6% and 24.5%. Ultra-high-performance liquid chromatography tandem mass spectrometry analysis revealed that the three MC congeners were electrochemically degraded through aromatic ring oxidation, alkene oxidation, and bond cleavage on the ADDA (3-amino-9-methoxy-2,6,8-trimethyl-10-phenyldeca-4,6-dienoic acid) side chain. Notably, the removal of MCs was accompanied by a decline in the hardness of the reaction water. This study provided insights into electrochemical degradation of microcystins and antibiotics in natural water, offering suggestions for its practical application.

Assessment of dietary yeast-based additives for cultured catfish and tilapia health

Channel catfish (Ictalurus punctatus) and Nile tilapia (Oreochromis niloticus) are two aquaculture species of great importance. Intensive production is often hindered by poor growth performance and disease mortality. The aim of this study was to evaluate the potential of a commercial fermented yeast product, DVAQUA, on channel catfish and Nile tilapia growth performance metrics and disease resistance. Channel catfish and Nile tilapia were fed practical diets supplemented with 0%, 0.1% or 0.4% of DVAQUA over approximately 2-month feeding periods in recirculation aquaculture systems. To assess the potential of the postbiotic against common aquaculture pathogens, juvenile catfish were subsequently challenged by immersion with Edwardsiella ictaluri S97-773 or virulent Aeromonas hydrophila ML09-119. Nile tilapia juveniles were challenged by injection with Streptococcus iniae ARS-98-60. Serum lysozyme activity, blood chemistry and growth metrics were measured at the end of the feeding period, but no differences were observed across the different metrics, except for survival. For the pathogen challenges, there were no differences in endpoint mortality for channel catfish with either pathogen (p > .05). In contrast, Nile tilapia survivability to S. iniae infection increased proportionally to the inclusion of DVAQUA (p = .005). Changes to sera lysozyme activity were also noted in the tilapia trial, with a reduction of activity in the fish fed the 0.4% DVAQUA diet compared to the control diet (p = .031). Expression profiles of proinflammatory genes and antibodies were also found to be modulated in channel catfish fed the postbiotic, indicating some degree of protective response. These results suggest that this postbiotic may be beneficial in protecting Nile tilapia against S. iniae infection by influencing immune parameters and additional research is needed to evaluate the potential of this DVAQUA for improving catfish health and disease control.

Pharmaceuticals and personal care products contamination in the rivers of Chennai city during the COVID-19 pandemic

Pharmaceuticals and personal care products (PPCPs) monitoring in surface water is crucial to address the escalating threat of antimicrobial resistance and safeguard public health. This study aimed to investigate the occurrence of 21 different PPCPs, including wastewater chemical markers, antibiotics, and parabens in the surface water of Chennai city using Ultra Performance Liquid Chromatography-Triple Quadrupole Mass Spectrometry (UPLC-MS/MS) analysis. It is noteworthy that chemical markers viz., carbamazepine (CBZ) and caffeine (CAF) were detected in all the sites and contributed to more than 95% of the total PPCPs load indicating a significant intrusion of wastewater. Among the antibiotics, fluoroquinolones were dominant in this study. Interestingly, a significant and strong correlation was seen between fluoroquinolones, CBZ and CAF (R2 = 0.880-0.928, p < 0.05), suggesting similarities in their sources. More than 50% of the sites exhibited a risk for antimicrobial resistance (RQAMR) with RQAMR > 1 for ciprofloxacin, indicating a significant public health concern. The ecotoxicological risk assessment of PPCPs showed no risk to any organisms, except for triclosan, which posed a risk to fish and daphnids at one site near an open drain in Buckingham canal.

In vitro impacts of polystyrene microplastics and environmental pollutants on ethoxyresorufin-O-deethylase and glutathione S-transferase activity in Mossambica tilapia

Microplastic (MP) pollution is a potential threat to marine organisms. In vitro toxicity of MPs and other pollutants, such as pharmaceutically active compounds (PhACs) and brominated flame retardants (BFRs), has been understudied. This study aimed to investigate the effects of polystyrene microplastics (PS-MPs) with different particle sizes on two biomarkers: ethoxyresorufin-O-deethylase (EROD) and glutathione S-transferase (GST) in tilapia liver homogenates. The study also examined the combined effects of PS-MPs with various environmental contaminants, including three metal ions (Cu2+, Zn2+, Pb2+), three BFRs, and six PhACs. PS-MPs alone had no remarkable effects on the two biomarkers at the selected concentrations. However, PS-MPs combined with other pollutants significantly affected the two biomarkers in most situations. For EROD activity, PS + metal ions (except Zn2+ at 1000 μg/L), PS + BFRs (except decabromodiphenyl oxide (BDE-209)) or PS+ trimethoprim (TMP) significantly inhibited activity values, whereas PS+ 4-acetaminophen (AMP) induced EROD activity. For GST, PS together with most tested pollutants (except PS+ ibuprofen (IBF)) greatly decreased the activities. Accordingly, future research should focus on combined toxicity of mixtures to set more reasonable environmental safety evaluation standards.

Antibiotics and polycyclic aromatic hydrocarbons in marine food webs of the Yellow River Estuary: Occurrence, trophic transfer, and human health risks

Antibiotics and polycyclic aromatic hydrocarbons (PAHs) are common environmental contaminants in the aquatic region encompassing the estuary of the Yellow River and Laizhou Bay. But little information is available about the trophic transfer of antibiotics and PAHs in the marine food web of this area. This study investigated the occurrence and trophic transfer of 19 antibiotics and 16 PAHs in marine organisms from a food web of Laizhou Bay of the Yellow River estuary. Sulfonamides, fluoroquinolones, and 2 to 4-ring PAHs were the dominant contaminants in organisms. There was a significant positive correlation between the log total concentration of sulfonamides and trophic level (TL). Sulfadiazine, sulfamethazine, and erythromycin had biomagnification effects, while ciprofloxacin and ofloxacin had biological dilution effects. The log total concentration of PAHs had a significant negative correlation with TL. Naphthalene, fluorene, anthracene, pyrene, and benzo[g,h,i]perylene had biological dilution effects. The distinct correlations of trophic magnification factors Dow of antibiotics and Kow of 2 to 5-ring PAHs, indicating that the potential of these two coefficients for predicting their transfer. Risk assessment indicated that the consumption of seafood containing antibiotics and PAHs in Laizhou Bay of the Yellow River estuary posed health and carcinogenic risks to human, respectively.

Profiles, drivers, and prioritization of antibiotics in China's major rivers

Through a systematic review of literature references from 2007 to 2022, we compiled a comprehensive national dataset comprising over 67,000 records and covering information on 129 antibiotics detected in the surface water and sediments of China's major rivers. Our analysis revealed notably high antibiotic concentrations in the Liaohe and Yellow Rivers. Among the antibiotics examined, sulfonamides, quinolones, and tetracyclines exhibited relatively high median concentrations in river water. Regional distribution analysis highlighted increased antibiotic levels in Shandong and Tianjin compared to other areas. Partial least squares path modeling revealed that animal production and pollution discharge positively influenced antibiotic levels in river water, whereas natural and socioeconomic factors had negative impacts. Based on the ecological risk assessment, we formulated a prioritized national list of antibiotics, with sulfonamides having the largest number of entries, followed by quinolones. Importantly, our analysis revealed a declining trend in antibiotic concentrations and the associated risk levels across China during the study period. This study not only enhances our understanding of antibiotic distribution in China's water systems, but also contributes to the development of a scientifically sound approach for prioritizing antibiotics. Ultimately, these findings will inform targeted antibiotic management and control strategies. ENVIRONMENTAL IMPLICATION: Antibiotics, posing threats to ecosystems and human health, exhibit pseudo-persistence in the environment. we compiled a national dataset of over 67,000 records on antibiotics, our study scrutinized antibiotic distribution in China's major river water and sediment. Through this analysis, we identified key factors influencing distribution patterns and crafted a national priority ranking for antibiotics. These findings deepen our understanding of antibiotic presence and contribute to the development of targeted management strategies aimed at minimizing environmental impact.

Occurrence, Source Apportionment, and Risk Assessment of Antibiotics in Mangrove Sediments from the Lianzhou Bay, China

In recent years, the widespread application of antibiotics has raised global concerns, posing a severe threat to ecological health. In this study, the occurrence, source, and ecological risks of 39 antibiotics belonging to 5 classes in mangrove sediments from Lianzhou Bay, China, were assessed. The total concentrations of the antibiotics (∑39 antibiotics) ranged from 65.45 to 202.24 ng/g dry weight (dw), with an average of 142.73 ± 36.76 ng/g dw. The concentrations of these five classes of antibiotics were as follows: Sulfonamides (SAs) > Tetracyclines (TCs) > Fluoroquinolones (QUs) > Penicillin (PCs) > Macrolides (MLs). The spatial distribution of antibiotics varied as high tidal zone > middle tidal zone > low tidal zone. The total organic carbon (TOC), pH, nitrate (NO3--N), and nitrite (NO2--N) of the sediment significantly influenced the distribution of antibiotics (p < 0.05). A source analysis identified untreated sewage from aquaculture as the primary source of antibiotics in the local mangrove. A risk assessment revealed that ciprofloxacin, norfloxacin, ofloxacin of QUs, and tetracycline of TCs exhibited medium risks to algae in certain sampling sites, while other antibiotics exhibited low or no risks to all organisms. Nevertheless, the total risk of all the detected antibiotics to algae was medium in 95% of the sites. The overall ecological risk level of antibiotics in the middle tidal zone was slightly lower than in the high tidal zone and the lowest in the low tidal zone. In summary, the experimental results provided insights into the fate and transport behaviors of antibiotics in mangrove sediments from Lianzhou Bay.

Antibiotic residue contamination in the aquatic environment, sources and associated potential health risks

Antibiotic residues are widely recognized as major pollutants in the aquatic environment on a global scale. As a significant class of pharmaceutically active compounds (PhACs), antibiotics are extensively consumed worldwide. The primary sources of these residues include hospitals, municipal sewage, household disposal, and manures from animal husbandry. These residues are frequently detected in surface and drinking waters, sewage effluents, soils, sediments, and various plant species in countries such as China, Japan, South Korea, Europe, the USA, Canada, and India. Antibiotics are used medicinally in both humans and animals, with a substantial portion excreted into the environment as metabolites in feces and urine. With the advancement of sensitive and quantitative analytical techniques, antibiotics are consistently reported in environmental matrices at concentrations ranging from nanograms per liter (ng/L) to milligrams per liter (mg/L). Agricultural soils, in particular, serve as a significant reservoir for antibiotic residues due to their strong particle adsorption capacities. Plants grown in soils irrigated with PhAC-contaminated water can uptake and accumulate these pharmaceuticals in various tissues, such as roots, leaves, and fruits, raising serious concerns regarding their consumption by humans and animals. There is an increasing need for research to understand the potential human health risks associated with the accumulation of antibiotics in the food chain. The present reviews aims to shed light on the rising environmental pharmaceutical contamination concerns, their sources in the environment, and the potential health risks as well as remediation effort. To discuss the main knowledge gaps and the future research that should be prioritized to achieve the risk assessment. We examined and summarized the available data and information on the antibiotic resistance associated with antibiotic residues in the environment. As studies have indicated that vegetables can absorb, transport, and accumulate antibiotics in edible parts when irrigated with wastewater that is either inadequately treated or untreated. These residues and their metabolites can enter the food chain, with their persistence, bioaccumulation, and toxicity contributing to drug resistance and adverse health effects in living organisms.

Ecological risk assessment of commonly used antibiotics in aquatic ecosystems along the coast of China

The consistent input of antibiotics into aquatic environments may pose risks to various creatures and ecosystems. However, risk assessment of pharmaceuticals and personal care products (PPCPs) in aquatic environments is frequently limited by the lack of toxicity data. To investigate the risk of commonly used antibiotics to various aquatic creatures, we focused on the distribution patterns and temporal dynamics of antibiotics in the coastal estuary area of China and performed a comprehensive ecological risk assessment for four antibiotics: erythromycin (ERY), tetracycline (TCN), norfloxacin (NOR) and sulfamethoxazole (SMX). An interspecies correlation estimation (ICE)-species sensitivity distribution (SSD) combined model was applied to predict the toxicity data of untested aquatic species, and an accurate ecological risk assessment procedure was developed to evaluate the risk level of PPCPs. The results of risk quotient assessments and probabilistic risk assessments (PRAs) suggested that four objective antibiotics in the Chinese coastal estuary area were at a low risk level. These antibiotics posed a high risk in antibiotic-related global hot spots, with probabilistic risk values for ERY, NOR, SMX, and TCN of 81.33 %, 27.08 %, 21.13 %, and 15.44 %, respectively. We applied an extrapolation method to overcome the lack of toxicity data in ecological risk assessment, enhanced the ecological reality of water quality criteria derivation and reduced the uncertainty of risk assessment for antibiotics.

Toxicity of the sunscreen UV filter benzophenone-3 (OBZ) to the microalga Selenastrum capricornutum: An insight into OBZ's damage to photosynthesis and respiration

Oxybenzone (OBZ; benzophenone-3, CAS# 131-57-7), as a new pollutant and ultraviolet absorbent, shows a significant threat to the survival of phytoplankton. This study aims to explore the acute toxic effects of OBZ on the growth of the microalga Selenastrum capricornutum, as well as the mechanisms for its damage to the primary metabolic pathways of photosynthesis and respiration. The results demonstrated that the concentrations for 50 % of maximal effect (EC50) of OBZ for S. capricornutum were 9.07 mg L-1 and 8.54 mg L-1 at 72 h and 96 h, respectively. A dosage of 4.56 mg L-1 OBZ significantly lowered the photosynthetic oxygen evolution rate of S. capricornutum in both light and dark conditions for a duration of 2 h, while it had no effect on the respiratory oxygen consumption rate under darkness. OBZ caused a significant decline in the efficiency of photosynthetic electron transport due to its damage to photosystem II (PSII), thereby decreasing the photosynthetic oxygen evolution rate. Over-accumulated H2O2 was produced under light due to the damage caused by OBZ to the donor and acceptor sides of PSII, resulting in increased peroxidation of cytomembranes and inhibition of algal respiration. OBZ's damage to photosynthesis and respiration will hinder the conversion and reuse of energy in algal cells, which is an important reason that OBZ has toxic effects on S. capricornutum. The present study indicated that OBZ has an acute toxic effect on the microalga S. capricornutum. In the two most important primary metabolic pathways in algae, photosynthesis is more sensitive to the toxicity of OBZ than respiration, especially in the dark.

Migration and transformation behaviors of antibiotics in water-sediment system under simulated light and wind waves

Antibiotics can generally be detected in the water-sediment systems of lakes. However, research on the migration and transformation of antibiotics in water-sediment systems based on the influences of light and wind waves is minimal. To address this research gap, we investigated the specific impacts of light and wind waves on the migration and transformation of three antibiotics, norfloxacin (NOR), trimethoprim (TMP), and sulfamethoxazole (SMX), under simulated light and wind waves disturbance conditions in a water-sediment system from Taihu Lake, China. In the overlying water, NOR was removed the fastest, followed by TMP and SMX. Compared to the no wind waves groups, the disturbance of big wind waves reduced the proportion of antibiotics in the overlying water. The contributions of light and wind waves to TMP and SMX degradation were greater than those of microbial degradation. However, the non-biological and biological contributions of NOR to degradation were almost equal. Wind waves had a significant impact on the microbial community changes in the sediment, especially in Methylophylaceae. These results verified the influence of light and wind waves on the migration and transformation of antibiotics, and provide assistance for the risk of antibiotic occurrence in water and sediments.

Antibiotics in Surface Sediments from the Anning River in Sichuan Province, China: Occurrence, Distribution, and Risk Assessment

The occurrence, distribution, and ecological risk assessment of 36 antibiotics from five groups, including macrolides (MLs), fluoroquinolones (FQs), tetracyclines (TCs), amphenicols (APs), and sulfonamides (SAs), were investigated for the first time in the Anning River, Sichuan Province, China. The results show that antibiotics were widely present in the sediments of the Anning River, with a total of 22 antibiotics detected. FQs were among the most abundant antibiotics, followed by TCs, MLs, APs, and SAs. The total concentrations of antibiotics in surface sediments varied from 0.05 to 53.35 ng/g, with an average of 8.09 ng/g. Among these groups, MLs, FQs, and TCs emerged as the predominant classes of antibiotics. The midstream sediments showed the highest residual levels of antibiotics, with lower levels observed in the downstream and upstream sediments. Anthropogenic activities, such as human clinical practices and animal breeding, might be sources of antibiotics released into the river. An ecological risk assessment revealed that trimethoprim from the SA group exhibited high risks, and MLs showed medium risks in the Anning River, whereas most antibiotics presented minimal to low risks. This study provides valuable information on antibiotic pollution in the upstream region of the Yangtze River, and future management measures are needed for the Anning River.

A Review on Fluoroquinolones' Toxicity to Freshwater Organisms and a Risk Assessment

Fluoroquinolones (FQs) have achieved significant success in both human and veterinary medicine. However, regulatory authorities have recommended limiting their use, firstly because they can have disabling side effects; secondly, because of the need to limit the spread of antibiotic resistance. This review addresses another concerning consequence of the excessive use of FQs: the freshwater environments contamination and the impact on non-target organisms. Here, an overview of the highest concentrations found in Europe, Asia, and the USA is provided, the sensitivity of various taxa is presented through a comparison of the lowest EC50s from about a hundred acute toxicity tests, and primary mechanisms of FQ toxicity are described. A risk assessment is conducted based on the estimation of the Predicted No Effect Concentration (PNEC). This is calculated traditionally and, in a more contemporary manner, by constructing a normalized Species Sensitivity Distribution curve. The lowest individual HC5 (6.52 µg L-1) was obtained for levofloxacin, followed by ciprofloxacin (7.51 µg L-1), sarafloxacin and clinafloxacin (12.23 µg L-1), and ofloxacin (17.12 µg L-1). By comparing the calculated PNEC with detected concentrations, it is evident that the risk cannot be denied: the potential impact of FQs on freshwater ecosystems is a further reason to minimize their use.

Trophic transfer of antibiotics in the benthic-pelagic coupling foodweb in a macrophyte-dominated shallow lake: The importance of pelagic-benthic coupling strength and baseline organism

In lake ecosystems, pelagic-benthic coupling strength (PBCS) is closely related to foodweb structure and pollutant transport. However, the trophic transfer of antibiotics in a benthic-pelagic coupling foodweb (BPCFW) and the manner in which PBCS influences the trophic magnification factor (TMFs) of antibiotics is still not well understood in the whole lake. Herein, the trophic transfer behavior of 12 quinolone antibiotics (QNs) in the BPCFW of Baiyangdian Lake were studied during the period of 2018-2019. It was revealed that 24 dominant species were contained in the BPCFW, and the trophic level was 0.42-2.94. Seven QNs were detected in organisms, the detection frequencies of ofloxacin (OFL), flumequine (FLU), norfloxacin (NOR), and enrofloxacin (ENR) were higher than other QNs. The ∑QN concentration in all species was 11.3-321 ng/g dw. The TMFs for ENR and NOR were trophic magnification, while for FLU/OFL it was trophic dilution. The PBCS showed spatial-temporal variation, with a range of 0.6977-0.7910. The TMFs of ENR, FLU, and OFL were significantly positively correlated with PBCS. Phytoplankton and macrophyte biomasses showed indirect impact on the TMFs of QNs by directly influencing the PBCS. Therefore, the PBCS was the direct influencing factor for the TMFs of chemicals.

Occurrence, distribution, and risk assessment of antibiotics in a typical aquaculture area around the Dongzhai Harbor mangrove forest on Hainan Island

The trees of the Dongzhai Harbor mangrove forest suffer from antibiotic contamination from surrounding aquaculture areas. Despite this being one of the largest mangrove forests in China, few studies have focused on the antibiotic pollution status in these aquaculture areas. In the present study, the occurrence, distribution, and risk assessment of 37 antibiotics in surface water and sediment samples from aquaculture areas around Dongzhai Harbor mangrove forests were analyzed. The concentration of total antibiotics (∑antibiotics) ranged from 78.4 ng/L to 225.6 ng/L in surface water (except S14-A2) and from 19.5 ng/g dry weight (dw) to 229 ng/g dw in sediment. In the sediment, the concentrations of ∑antibiotics were relatively low (19.5-52.3 ng/g dw) at 75 % of the sampling sites, while they were high (95.7-229.0 ng/g dw) at a few sampling sites (S13-A1, S13D, S8D). The correlation analysis results showed that the Kd values of the 9 antibiotics were significantly positively correlated with molecular weight (MW), Kow, and LogKow. Risk assessment revealed that sulfamethoxazole (SMX) in surface water and SMX, enoxacin (ENX), ciprofloxacin (CFX), enrofloxacin (EFX), ofloxacin (OFX), and norfloxacin (NFX) in sediment had medium/high risk quotients (RQs) at 62.5 % and 25-100 %, respectively, of the sampling sites. The antibiotic mixture in surface water (0.06-3.36) and sediment (0.43-309) posed a high risk at 37.5 % and 66.7 %, respectively, of the sampling sites. SMX was selected as an indicator of antibiotic pollution in surface water to assist regulatory authorities in monitoring and managing antibiotic pollution in the aquaculture zone of Dongzhai Harbor. Overall, the results of the present study provide a comprehensive and detailed analysis of the characteristics of antibiotics in the aquaculture environment around the Dongzhai Harbor mangrove system and provide a theoretical basis for the source control of antibiotics in mangrove systems.

Environmental health hazards of untreated livestock wastewater: potential risks and future perspectives

Due to technological and economic limitations, waste products such as sewage and manure generated in livestock farming lack comprehensive scientific and centralized treatment. This leads to the exposure of various contaminants in livestock wastewater, posing potential risks to both the ecological environment and human health. This review evaluates the environmental and physical health risks posed by common pollutants in livestock wastewater and outlines future treatment methods to mitigate these risks. Residual wastes in livestock wastewater, including pathogenic bacteria and parasites surviving after epidemics or diseases on various farms, along with antibiotics, organic wastes, and heavy metals from farming activities, contribute to environmental damage and pose risks to human health. As the livestock industry's development increasingly impacts society's future negatively, addressing the issue of residual wastes in livestock wastewater discharge becomes imperative. Ongoing advancements in wastewater treatment systems are consistently updating and refining practices to effectively minimize waste exposure at the discharge source, mitigating risks to environmental ecology and human health. This review not only summarizes the "potential risks of livestock wastewater" but also explores "the prospects for the development of wastewater treatment technologies" based on current reports. It offers valuable insights to support the long-term and healthy development of the livestock industry and contribute to the sustainable development of the ecological environment.

Critical role of multiple antibiotics on the denitrification rate in groundwater: Field investigative proof

The impact of antibiotics on denitrification has emerged as a significant topic; however, there is a dearth of mechanistic understanding regarding the effects of multiple antibiotics at the ng/L level on denitrification in groundwater. This study conducted five field samplings between March 2019 and July 2021 at two representative monitoring wells. The investigation utilized metagenomic sequencing to unveil the antibiotic mechanisms influencing denitrification. Results revealed the detection of 16 out of 64 antibiotics, with a maximum detection frequency and total concentration of 100 % and 187 ng/L, respectively. Additionally, both nitrate and total antibiotic concentrations exhibited a gradual decrease along the groundwater flow direction. Metagenomic evidence indicated that denitrification served as the dominant biogeochemical process controlling nitrate attenuation in groundwater. However, the denitrification capacity experienced significant inhibition in the presence of multiple antibiotics at the ng/L level. This inhibition was attributed to decreases in the relative abundance of dominant denitrifying bacteria (Candidatus_Scalindua, Herminiimonas and unclassified_p_Planctomycetes) and denitrifying functional genes (narGH, nirKS and norB), signifying the pressure exerted by antibiotics on denitrifying bacteria. The variation in antibiotic concentration (∆Cantibiotics) indicated a change in antibiotic pressure on denitrifying bacteria. A larger ∆Cantibiotics corresponded to a greater rebound in the relative abundance of denitrifying functional genes, resulting in a faster denitrification rate (Kdenitrification). Field observations further demonstrated a positive correlation between Kdenitrification and ∆Cantibiotics. Comparatively, a higher Kdenitrification observed at higher ∆Cantibiotics was primarily due to the enrichment of more nondominant denitrifying bacteria carrying key denitrifying functional genes. In conclusion, this study underscores that multiple antibiotics at the ng/L level in groundwater inhibited denitrification, and the degree of inhibition was closely related to ∆Cantibiotics.

Cross-contamination and ecological risk assessment of antibiotics between rivers and surrounding open aquaculture ponds

Antibiotics are causing widespread concern as one of the emerging contaminants. There is the abuse of antibiotics in high-density open aquaculture, and the tailwater is often discharged into surrounding rivers. At the same time, the water replenishment of open aquaculture ponds from nearby rivers containing antibiotic contamination from different sources may result in cross-contamination. However, it is still unclear which pollution intensity is greater in rivers or in open aquaculture. So in this paper, the levels of 20 antibiotics (i.e., Fluoroquinolones (FQs), Sulfonamides (SAs), Tetracyclines (TCs), Macrolides (MLs) and Lincosamides (LCs)) in rivers and high-density open aquaculture ponds were investigated in the Baini River basin in the suburbs of Guangzhou, China. The results showed that norfloxacin (NFX) was the predominant antibiotic in river and aquaculture water, with concentrations ranging from 6.12 to 156.04 ng/L and from 7.47 to 82.62 ng/L in both aquatic systems, respectively. As for the pollution intensity of antibiotics, the annual pollution contribution (28.64 kg/a) of the river water supply to open aquaculture is higher than that (10.81 kg/a) of open aquaculture to the river, which means river pollution has a greater impact on aquaculture ponds. The risk quotient (RQ) showed that the ecological risk of lincomycin (LIN), erythromycin (ERY), sulfamethoxazole (SMX), norfloxacin (NFX), ciprofloxacin (CFX) and chlortetracycline (CTC) in rivers and aquaculture environments had high ecological risks from 1.21 to 1.81. Water interactions with contaminated rivers will result in a corresponding increase in the ecological risk of antibiotics in the aquaculture environment. Overall, according to the results, the risk of polluted rivers to open aquaculture cannot be ignored, and it is recommended that open aquaculture should use these water sources with caution, and that the water quality evaluation of aquaculture water should be increased with monitoring indicators for emerging contaminants such as antibiotics.

Antibiotics soil-solution chemistry: A review of environmental behavior and uptake and transformation by plants

The increased use of antibiotics by humans for various purposes has left the environment polluted. Antibiotic pollution remediation is challenging because antibiotics exist in trace amounts and only highly sensitive detection techniques could be used to quantify them. Nevertheless, their trace quantity is not a hindrance to their transfer along the food chain, causing sensitization and the development of antibiotic resistance. Despite an increase in the literature on antibiotic pollution and the development and transfer of antibiotic-resistant genes (ARGs), little attention has been given to the behavior of antibiotics at the soil-solution interface and how this affects antibiotic adsorption-desorption interactions and subsequent uptake and transformation by plants. Thus, this review critically examines the interactions and possible degradation mechanisms of antibiotics in soil and the link between antibiotic soil-solution chemistry and uptake by plants. Also, different factors influencing antibiotic mobility in soil and the transfer of ARGs from one organism to another were considered. The mechanistic and critical analyses revealed that: (a) the charge characteristics of antibiotics at the soil-root interface determine whether they are adsorbed to soil or taken up by plants; (b) antibiotics that avoid soil colloids and reach soil pore water can be absorbed by plant roots, but their translocation to the stem and leaves depends on the ionic state of the molecule; (c) few studies have explored how plants adapt to antibiotic pollution and the transformation of antibiotics in plants; and (d) the persistence of antibiotics in cropland soils can be influenced by the content of soil organic matter, coexisting ions, and fertilization practices. Future research should focus on the soil/solution-antibiotic-plant interactions to reveal detailed mechanisms of antibiotic transformation by plants and whether plant-transformed antibiotics could be of environmental risk.

Effects of the aquatic pollutant sulfamethoxazole on the innate immunity and antioxidant capacity of the mud crab Scylla paramamosain

Sulfamethoxazole (SMZ) is commonly used in aquaculture to treat bacterial infections, but its long-term residual properties in natural water can pose a direct threat to aquatic animals. This study is to investigate the effects of continuous exposure to SMZ on mud crabs (Scylla paramamosain) at four different concentrations (0, 10, 100, and 1000 ng/L) that reflect the range found in natural aquatic environments. The results confirmed that SMZ exposure reduced the expression levels of genes related to the innate immunity in mud crabs, including JAK, Astakine, TLR, and Crustin. It also stimulated oxidative stress, caused the production of reactive oxygen species and lower activities of antioxidant enzymes such as peroxidase, superoxide dismutase, catalase, and glutathione. SMZ exposure damaged the DNA of crab hemocytes and hepatopancreas tissue, and reduced the phagocytosis, ultimately leading to a decreased survival rates of mud crabs infected with Vibrio alginolyticus. These findings demonstrate that SMZ exposure has immunotoxic effects on mud crabs' innate immunity and reduces the ability to resist pathogen infections.

Environmental remediation of the norfloxacin in water by adsorption: Advances, current status and prospects

Antibiotics are considered as the new generation water pollutants as these disturb endocrine systems if water contaminated with antibiotics is consumed. Among many antibiotics norfloxacin is present in various natural water bodies globally. This antibiotic is considered an emerging pollutant due to its low degradation in aquatic animals. Besides, it has many side effects on human vital organs. Therefore, the present article discusses the recent advances in the removal of norfloxacin by adsorption. This article describes the presence of norfloxacin in natural water, consumption, toxicity, various adsorbents for norfloxacin removal, optimization factors for norfloxacin removal, kinetics, thermodynamics, modeling, adsorption mechanism and regeneration of the adsorbents. Adsorption takes place in a monolayer following the Langmuir model. The Pseudo-second order model represents the kinetic data. The adsorption capacity ranged from 0.924 to 1282 mg g-1. In this sense, the parameters such as the NFX concentration added to the adsorbent textural properties exerted a great influence. Besides, the fixed bed-based removal at a large scale is also included. In addition to this, the simulation studies were also discussed to describe the adsorption mechanism. Finally, the research challenges and future perspectives have also been highlighted. This article will be highly useful for academicians, researchers, industry persons, and government authorities for designing future advanced experiments.

Field migration of veterinary antibiotics via surface runoff from chicken-raising orchard in responding to natural rainfalls

Knowledge on runoff transport of manure-sourced antibiotics from farmland soil to aquatic environment is limited due to complexity of hydrological regime and pathways. This study monitored natural rainfalls in sloping orchard plots with free-range chickens, with an attempt to investigate the migration characteristics of typical antibiotics via surface runoff as well as the impact of manure presence. Results showed that rainstorms continuously carried away antibiotics in surface runoff and all target antibiotics including those with high affinities to soil were detected at the beginning of runoff production. Concentration of antibiotics was found to respond strongly to the instantaneous rainfall intensity, showing consistent fluctuations during rainfalls. Concentrations of sulfonamides and florfenicol were two orders of magnitude higher than that of tetracyclines and fluoroquinolones. Compared to the control without raising chickens, antibiotics migration was considerably increased with the increased runoff production due to soil surface changes caused by chicken activities. Additionally, dynamics of antibiotic concentration significantly correlated with variations of fluorescent DOM components. Chicken manure-derived DOM mainly contained tryptophan moiety, and laboratory fluorescence quenching test with 2D-COS analysis indicated that all antibiotics interacted more strongly and preferentially with tryptophan than humic-like species. Antibiotics bonded to manure DOM with an affinity corresponding to the significance level of their correlations. In this light, potential use of fluorescence indices based on the established correlations may provide a convenient tool for tracing runoff migration of antibiotics during rainfalls.

Effects of Antibiotic Residues on Fish Gut Microbiome Dysbiosis and Mucosal Barrier-Related Pathogen Susceptibility in Zebrafish Experimental Model

The symbiotic community of microorganisms in the gut plays an important role in the health of the host. While many previous studies have been performed on the interactions between the gut microbiome and the host in mammals, studies in fish are still lacking. In this study, we investigated changes in the intestinal microbiome and pathogen susceptibility of zebrafish (Danio rerio) following chronic antibiotics exposure. The chronic antibiotics exposure assay was performed on zebrafish for 30 days using oxytetracycline (Otc), sulfamethoxazole/trimethoprim (Smx/Tmp), or erythromycin (Ery), which are antibiotics widely used in the aquaculture industry. The microbiome analysis indicated that Fusobacteria, Proteobacteria, Firmicutes, and Bacteroidetes were the dominant phyla in the gut microbiome of the zebrafish used in this study. However, in Smx/Tmp-treated zebrafish, the compositions of Fusobacteria and Proteobacteria were changed significantly, and in Ery-treated zebrafish, the compositions of Proteobacteria and Firmicutes were altered significantly. Although alpha diversity analysis showed that there was no significant difference in the richness, beta diversity analysis revealed a community imbalance in the gut microbiome of all chronically antibiotics-exposed zebrafish. Intriguingly, in zebrafish with dysbiosis in the gut microbiome, the pathogen susceptibility to Edwardsiella piscicida, a representative Gram-negative fish pathogen, was reduced. Gut microbiome imbalance resulted in a higher count of goblet cells in intestinal tissue and an upregulation of genes related to the intestinal mucosal barrier. In addition, as innate immunity was enhanced by the increased mucosal barrier, immune and stress-related gene expression in the intestinal tissue was downregulated. In this study, we provide new insight into the effect of gut microbiome dysbiosis on pathogen susceptibility.

An update on the prevalence of colistin and carbapenem-resistant Gram-negative bacteria in aquaculture: an emerging threat to public health

Aquaculture has been recognized as a hotspot for the emergence and spread of antimicrobial resistance genes conferring resistance to clinically important antibiotics. This review gives insights into studies investigating the prevalence of colistin and carbapenem resistance (CCR) among Gram-negative bacilli in aquaculture. Overall, a high incidence of CCR has been reported in aquatic farms in several countries, with CCR being more prevalent among opportunistic human pathogens such as Acinetobacter nosocomialis, Shewanella algae, Photobacterium damselae, Vibrio spp., Aeromonas spp., as well as members of Enterobacteriaceae family. A high proportion of isolates in these studies exhibited wide-spectrum profiles of antimicrobial resistance, highlighting their multidrug-resistance properties (MDR). Several mobile colistin resistance genes (including, mcr-1, mcr-1.1, mcr-2, mcr-2.1, mcr-3, mcr-3.1, mcr-4.1, mcr-4.3, mcr-5.1, mcr-6.1, mcr-7.1, mcr-8.1, and mcr-10.1) and carbapenemase encoding genes (including, blaOXA-48, blaOXA-55, blaNDM, blaKPC, blaIMI, blaAIM, blaVIM, and blaIMP) have been detected in aquatic farms in different countries. The majority of these were carried on MDR Incompatibility (Inc) plasmids including IncA/C, and IncX4, which have been associated with a wide host range of different sources. Thus, there is a risk for the possible spread of resistance genes between fish, their environments, and humans. These findings highlight the need to monitor and regulate the usage of antimicrobials in aquaculture. A multisectoral and transdisciplinary (One Health) approach is urgently needed to reduce the spread of resistant bacteria and/or resistance genes originating in aquaculture and avoid their global reach.

Spatial trends and ecotoxic risk assessment of selected pharmaceuticals in sediments from Lake Victoria, Uganda, East Africa

Pharmaceutical residues in the aquatic environment are an emerging issue of global concern because of their effects on ecosystems including; antibacterial resistance development and endocrine disruption. Lake Victoria is the largest freshwater lake in Africa, and the second largest lake in the world. It is also the main source of the White Nile River, arguably the longest river in the world, flowing through South Sudan, Sudan, Ethiopia and Egypt, discharging into the Mediterranean Sea. However, its ecology is threatened by rapid industrialisation, urbanization, and increased agricultural activities, which have led to increased pollution via polluted runoffs. In this study, the occurrence of twenty-five pharmaceutical compounds (14 antibiotics, four anti-epileptic and antidepressant drugs, three analgesic and anti-inflammatory drugs, three beta-blockers, and one lipid regulator) was studied in 55 sediment samples obtained from the Ugandan sector of Lake Victoria, and their ecotoxic risk assessed. All the target compounds were quantifiable with levofloxacin (2-120 ng g-1 dm; dry mass), ciprofloxacin (3-130 ng g-1 dm) enoxacin (9-75 ng g-1 dm), ibuprofen (6-50 ng g-1 dm), metoprolol (1-92 ng g-1 dm) and propranolol (1-52 ng g-1 dm) being predominant. Murchison Bay, being the chief recipient of sewage effluents, municipal and industrial waste from Kampala city and its suburbs, had the highest levels. Ecotoxic risk assessment revealed that ciprofloxacin, levofloxacin, sulfamethoxazole, sulfamethazine, oxytetracycline, tetracycline, erythromycin, norfloxacin, ibuprofen, diclofenac, carbamazepine, atenolol, and metoprolol posed high toxic risks to sediment-dwelling organisms (risk quotients, RQ >1). This is the first study reporting concentrations and ecotoxic risks of pharmaceuticals in sediments of Lake Victoria, Uganda, and the whole of East Africa. Detection, identification and quantification of pharmaceuticals in Lake Victoria sediments is essential for gaining knowledge on their occurrence and fate which can ultimately be used to assist in constructing relevant policy and management recommendations.

Insight into typical photo-assisted AOPs for the degradation of antibiotic micropollutants: Mechanisms and research gaps

Due to the incomplete elimination by traditional wastewater treatment, antibiotics are becoming emerging contaminants, which are proved to be ubiquitous and promote bacterial resistance in the aquatic systems. Antibiotic pollution has raised particular concerns, calling for improved methods to clean wastewater and water. Photo-assisted advanced oxidation processes (AOPs) have attracted increasing attention because of the fast reaction rate, high oxidation capacity and low selectivity to remove antibiotics from wastewater. On the basis of latest literature, we found some new breakthroughs in the degradation mechanisms of antibiotic micropollutants with respect to the AOPs. Therefore, this paper summarizes and highlights the degradation kinetics, pathways and mechanisms of antibiotics degraded by the photo-assisted AOPs, including the UV/O3 process, photo-Fenton technology, and photocatalysis. In the processes, functional groups are attacked by hydroxyl radicals, and major structures are destroyed subsequently, which depends on the classes of antibiotics. Meanwhile, their basic principles, current applications and influencing factors are briefly discussed. The main challenges, prospects, and recommendations for the improvement of photo-assisted AOPs are proposed to better remove antibiotics from wastewater.

An integrated multimedia fate modeling framework for identifying mitigation strategy of antibiotic ecological risks: A case study in a peri-urban river

Antibiotics have been heavily used over the past decades, resulting in their frequent detections in rivers and increasing ecological risks. Recognizing characteristics of antibiotic ecological risks (AERs) and making effective strategies to mitigate the AERs are essential to ensure the safety of aquatic ecosystem and public health. In this study, an integrated technological framework has been proposed toward identifying management options for reducing AERs by jointly utilizing multimedia fugacity modelling and ecotoxicological risk assessment, and applied to characterize the AERs in a peri-urban river in Beijing. Specifically, a level III fugacity model has been successfully established to simulate the fate of antibiotics in the environment, and the manageable parameters have been screened out via sensitivity analysis of the model. Then the validated fugacity model has been used for scenario modellings to optimize mitigation strategies of AERs. Results show most of the antibiotics considered are frequently detected in the river, and pose medium or high risks to aquatic organisms. Relatively, the macrolides and fluoroquinolones present higher ecotoxicological risks than sulfonamides and tetracyclines. Furthermore, the mixture risk quotient and predictive equation of concentration addition suggest joint and synergistic/antagonistic effects of AERs for multiple or binary antibiotics in the environment. Largely, the concentrations of antibiotics in the river are determined by the source emissions into water and soil. Scenario modellings show the improvement of antibiotic removal rates would be considered preferentially to mitigate the AERs. Also, controlling human consumption is conducive to reducing the risks posed by tetracyclines, macrolides and trimethoprim, while controlling animal consumption would benefit the reduction for sulfonamides. Overall, the joint strategy presents the greatest reduction of AERs by reducing antibiotic consumption and together improving sewage treatment rate and antibiotic removal rate. The study provides us a useful guideline to make ecological risk-based mitigation strategy for reducing AERs in environment.

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.

Biofilm on the pipeline wall is an important transmission route of resistome in drinking water distribution system

Due to the intensive use of antibiotics, the drinking water distribution system (DWDS) has become one of the hotspots of antibiotic resistance. However, little is known about the role of biofilm in the aspect of spreading resistance in DWDS. In present study, four lab-scale biological annular reactors (BAR) were constructed to investigate the transmission of ARGs exposed to a certain amount of antibiotic (sulfamethoxazole) synergistic disinfectants. It was emphasized that pipe wall biofilm was an important way for ARGs to propagate in the pipeline, and the results were quantified by constructing an operational taxonomic unit (OTU) network map. The network analysis results showed the biofilm contribution to waterborne bacteria was finally estimated to be 51.45% and 34.27% in polyethylen (PE) pipe and ductile iron (DI) pipe, respectively. The proportion of vertical gene transfer (VGT) in biofilm was higher than that in water, and the occurrence of this situation had little relationship with the selection of pipe type. Overall, this study revealed how biofilm promoted the transmission of resistome in bulk water, which can provide insights into assessing biofilm-associated risks and optimizing pipe material selection for biofilm control in DWDS.

Photocatalytic degradation of a typical macrolide antibiotic roxithromycin using polypropylene fibre sheet supported N-TiO2/graphene oxide composite materials

The post-treatment of recycling the fine photocatalyst nanoparticles restricts their application. In this study, a new photocatalytic material was synthesized by immobilizing the N-doped TiO2 and graphene oxide (GO) composite on polypropylene (PP) (N-TiO2/GO/PP) fibre sheet, and characterized based on X-ray diffraction spectroscopy (XRD), Raman spectroscopy and Scanning Electron Microscope (SEM). The photocatalytic activity was evaluated using roxithromycin (ROX) as a typical antibiotic pollutant. XRD, Raman spectra and SEM images proved that N-TiO2/GO/PP fibre sheet was successfully synthesized. The photocatalytic degradation of 10 mg L-1 ROX can reach up to 90% and the degradation rate constant was 0.2299 h-1 in surface water with the application amount of TiO2/GO/PP fibre sheet of 24.6 cm × 2.7 cm and reaction time of 9 h under the irradiation of simulated sunlight. The application amount of TiO2/GO/PP fibre sheet, initial concentration of ROX and water matrix significantly affect the degradation of ROX. A low concentration of natural organic matter (NOM) slightly promoted the degradation of ROX, while a high concentration of NOM significantly inhibited the degradation of ROX. Alkaline condition (pH 8-9) is favourable for the photocatalytic degradation of ROX by TiO2/GO/PP fibre sheet. The photocatalytic reactivity of the TiO2/GO/PP fibre sheet showed no significant decrease after three runs. Two primary degradation products of ROX were identified and they showed lower ecotoxicity than ROX. The results demonstrate that the new synthesized TiO2/GO/PP fibre sheet shows promising application prospects in the treatment of antibiotics in wastewater and surface waters.

An overview on the prevalence and potential impact of antimicrobials and antimicrobial resistance in the aquatic environment of India

India at present is one of the leading countries in antimicrobial drug production and use, leading to increasing antimicrobial resistance (AMR) and public health problems. Attention has mainly been focused on the human and food animals' contribution to AMR neglecting the potential contribution of the perceptibly degraded aquatic environment in India. The paper reviews the available published literature in India on the prevalence of antimicrobial residues and their dissemination pathways in wastewater of pharmaceutical industries, sewage treatment plants, hospitals, riverine, community pond water, and groundwater. The prevalence of antimicrobial residue concentration, pathogenic and non-pathogenic bacteria antimicrobial resistant bacteria (ARB), their drug resistance levels, and their specific antimicrobial resistant genes (ARGs) occurring in various water matrices of India have been comprehensively depicted from existing literature. The concentration of some widely used antimicrobials recorded from the sewage treatment plants and hospital wastewater and rivers in India has been compared with other countries. The ecotoxicological risk posed by these antimicrobials in the various water matrices in India indicated high hazard quotient (HQ) values for pharmaceutical effluents, hospital effluents, and river water. The degraded aquatic environment exhibited the selection of a wide array of co-existent resistant genes for antibiotics and metals. The review revealed improper use of antibiotics and inadequate wastewater treatment as major drivers of AMR contaminating water bodies in India and suggestion for containing the challenges posed by AMR in India has been proposed.

Nanoscale designing of metal organic framework moieties as efficient tools for environmental decontamination

Environmental pollutants, being a major and detrimental component of the ecological imbalance, need to be controlled. Serious health issues can get intensified due to contaminants present in the air, water, and soil. Accurate and rapid monitoring of environmental pollutants is imperative for the detoxification of the environment and hence living beings. Metal-organic frameworks (MOFs) are a class of porous and highly diverse adsorbent materials with tunable surface area and diverse functionality. Similarly, the conversion of MOFs into nanoscale regime leads to the formation of nanometal-organic frameworks (NMOFs) with increased selectivity, sensitivity, detection ability, and portability. The present review majorly focuses on a variety of synthetic methods including the ex situ and in situ synthesis of MOF nanocomposites and direct synthesis of NMOFs. Furthermore, a variety of applications such as nanoabsorbent, nanocatalysts, and nanosensors for different dyes, antibiotics, toxic ions, gases, pesticides, etc., are described along with illustrations. An initiative is depicted hereby using nanostructures of MOFs to decontaminate hazardous environmental toxicants.

Deciphering the distribution and microbial secretors of extracellular polymeric substances associated antibiotic resistance genes in tube wall biofilm

Antibiotics and disinfectants have both been proposed to exert selective pressures on the biofilm as well as affecting the emergence and spread of antibiotic resistance genes (ARGs). However, the transfer mechanism of ARGs in drinking water distribution system (DWDS) under the coupling effect of antibiotics and disinfectants has not been completely understood. In the current study, four lab-scale biological annular reactors (BARs) were constructed to evaluate the effects of sulfamethoxazole (SMX) and NaClO coupling in DWDS and reveal the related mechanisms of ARGs proliferation. TetM was abundant in both the liquid phase and the biofilm, and redundancy analysis showed that the total organic carbon (TOC) and temperature were significantly correlated with ARGs in the water phase. There was a significant correlation between the relative abundance of ARGs in the biofilm phase and extracellular polymeric substances (EPS). Additionally, the proliferation and spread of ARGs in water phase were related to microbial community structure. Partial least-squares path modeling showed that antibiotic concentration may influence ARGs by affecting MGEs. These findings help us to better understand the diffusion process of ARGs in drinking water and provide a theoretical support for technologies to control ARGs at the front of pipeline.

Characteristics of antibiotic resistance genes and microbial community distribution in Wanfeng Lake, upper Pearl River, China

Wanfeng Lake, a highland lake in the upper part of the Pearl River Basin, China, has long been disturbed by aquaculture and human activities, resulting in the accumulation of antibiotics and antibiotic resistance genes (ARGs), which pose a major threat to humans and animals. In this study, 20 antibiotics, 9 ARGs, 2 mobile genetic elements (intl1 and intl2), and microbial community structure were investigated in Wanfeng Lake. The results of the study showed that the total concentration of antibiotics in surface water was 372.72 ng/L, with ofloxacin (OFX) having the highest concentration (169.48 ng/L), posing a high ecological risk to aquatic organisms. The total concentration of antibiotics in sediments was 235.86 ng/g, with flumequine (FLU) having the highest concentration (122.54 ng/g). This indicates that the main type of antibiotics in Wanfeng Lake are quinolones. QPCR analysis results of the relative abundance of ARGs in both surface water and sediments showed that sulfonamide resistance genes > macrolide resistance genes > tetracycline resistance genes > quinolone resistance genes, indicating that sulfonamide resistance genes were the dominant type. The metagenomic results showed that the predominant microorganisms in the sediment under the phylum level were Planctomycetes, Proteobacteria, Euryarchaeota, and Chloroflexi. Pearson's correlation analysis showed a significantly positive correlation between antibiotics and environmental factors with ARGs in Wanfeng Lake and a significant positive correlation between antibiotics and ARGs with microorganisms in sediments. This suggests that there is a potential pressure of antibiotics on ARGs, while microorganisms provide the driving force for the evolution and spread of ARGs. This study provides a basis for further research on the occurrence and spread of antibiotics and ARGs in Wanfeng Lake. A total of 14 antibiotics were detected in surface water and sediments. OFX poses a high ecological risk in all points of surface water. Antibiotics and ARGs were significantly positively correlated in Wanfeng Lake. Antibiotics and ARGs in sediments were positively correlated with microorganisms.

Sulfonamides (SAs) exposure causes neurobehavioral toxicity at environmentally relevant concentrations (ERCs) in early development of zebrafish

Antibiotics, due to their stability and persistence in the environment, can have chronic impacts on various ecosystems and organisms. However, the molecular mechanisms underlying antibiotic toxicity at environmental concentrations, particularly the neurotoxic effects of sulfonamides (SAs), remain poorly understood. In this study, we assessed the neurotoxicity of six SAs including the sulfadiazine (SD), sulfathiazole (ST), sulfamethoxazole (SMX), sulfisoxazole (SIZ), sulfapyridine (SPD), and sulfadimethoxine (SDM) by exposing zebrafish to environmentally relevant concentrations (ERCs). The SAs exhibited concentration-dependent effects on zebrafish behavior, including spontaneous movement, heartbeat, survival rate, and body metrics, ultimately leading to depressive-like symptoms and sublethal toxicity during early life stages. Notably, even the lowest SA concentration (0.05 μg/L) induced neurotoxicity and behavioral impairment in zebrafish. We observed a dose-dependent increase in melancholy behavior as indicated by increased resting time and decreased motor activity in zebrafish larvae. Following exposure to SAs from 4 to 120 h post-fertilization (hpf), key genes involved in folate synthesis [sepiapterin reductase a (spra), phenylalanine hydroxylase (pah), tyrosine hydroxylase (th), and tryptophan hydroxylase 1 (tryptophan 5-monooxygenase) a tryptophan hydroxylase (tph1a)] and carbonic anhydrase (CA) metabolism [carbonic anhydrase II (ca2), carbonic anhydrase IV a (ca4a), carbonic anhydrase VII (ca7), and carbonic anhydrase XIV (ca14)] were significantly downregulated or inhibited at different concentrations. Our findings demonstrate that acute exposure to six SAs at environmentally relevant concentrations induces developmental and neurotoxic effects in zebrafish, impacting folate synthesis pathways and CA metabolism. These results provide valuable insights into the potential role of antibiotics in depressive disorders and neuroregulatory pathways.

Metagenomic analysis to determine the characteristics of antibiotic resistance genes in typical antibiotic-contaminated sediments

Comprehensive studies of the effects of various physical and chemical variables (including heavy metals), antibiotics, and microorganisms in the environment on antibiotic resistance genes are rare. We collected sediment samples from the Shatian Lake aquaculture area and surrounding lakes and rivers located in Shanghai, China. The spatial distribution of sediment ARGs was assessed by metagenomic analysis that revealed 26 ARG types (510 subtypes), dominated by Multidrug, β-lactam, Aminoglycoside, Glycopeptides, Fluoroquinolone, and Tetracyline. Redundancy discriminant analysis indicated that antibiotics (SAs and MLs) in the aqueous environment and sediment along with water TN and TP were the key variables affecting the abundance distribution of total ARGs. However, the main environmental drivers and key influences differed among the different ARGs. For total ARGs, the environmental subtypes affecting their structural composition and distribution characteristics were mainly antibiotic residues. Procrustes analysis showed a significant correlation between ARGs and microbial communities in the sediment in the survey area. Network analysis revealed that most of the target ARGs were significantly and positively correlated with microorganisms, and a small number of ARGs (e.g., rpoB, mdtC, and efpA) were highly significantly and positively correlated with microorganisms (e.g., Knoellia, Tetrasphaera, and Gemmatirosa). Potential hosts for the major ARGs included Actinobacteria, Proteobacteria, and Gemmatimonadetes. Our study provides new insight and a comprehensive assessment of the distribution and abundance of ARGs and the drivers of ARG occurrence and transmission.

Spatial variability, source identification and risks assessment of antibiotics in multimedia of North China's largest freshwater lake using positive matrix factorization and Monte Carlo simulation

Antibiotics are widely found in aquatic ecosystems and pose a serious threat to human and the ecological system. Samples of surface water (SW), overlying water (OW), pore water (PW) and sediments (Sedi) were collected to investigate the spatial variability, potential sources, ecological risk (RQs) and health risks (HQs) of nine common antibiotics in Baiyangdian Lake using positive matrix factorization (PMF), and Monte Carlo simulation. Significant spatial autocorrelation of most antibiotics were observed in PW and Sedi samples rather than in SW and OW samples, and higher antibiotic levels were found in the northwest of waters and the southwest of sediments. Livestock (26.74-35.57%) and aquaculture (21.62-37.70%) were identified as primary sources of antibiotics in the water and sediments. Norfloxacin and roxithromycin showed high levels of RQ and HQ in more than 50% of samples, respectively. The combined RQ (ΣRQ) in the PW can be used as a sign of across multimedia risk. Notably, appreciable health risks were observed for the combined HQ (ΣHQ) in about 80% of samples, indicating the importance of taking health risk of antibiotics into consideration. The findings of this work provides a reference for antibiotics pollution control and risk management in shallow lake.

Antibiotic pollution of the Yellow River in China and its relationship with dissolved organic matter: Distribution and Source identification

Understanding the sources of antibiotics is important for managing antibiotic contamination and preventing environmental risks in the aquatic environment. In this study, the distribution of dissolved organic matter (DOM) and 24 antibiotics from four typical classes (quinolones, macrolides, sulfonamides and tetracyclines) in the Yellow River basin containing distinct sources of pollution was investigated. In particular, relationships between the antibiotic concentrations and fluorescent properties of DOM were to be established to identify antibiotic sources. A total of 22 antibiotics were detected, with maximum concentrations ranging from 0.27 to 30.14 ng/L in the mainstream of the Yellow River. Of these antibiotics, only erythromycin (ERY) and sulfamethoxazole (SMX) posed potential risks to aquatic organisms. Spatially, tetracyclines were mainly distributed in the upstream reaches of the river, and quinolones were largely distributed in the midstream. High levels of sulfonamides were present downstream of the investigated river. Only EYR belonging to the macrolide group was detected and had a high downstream concentration. EEM-PARAFAC analysis showed that DOM was composed of visible fulvic acid-like fluorescence fraction (C1), ultraviolet fulvic acid-like fluorescence fraction (C2) and protein-like fraction (C3). Using Pearson correlation analysis, this study demonstrated a close relationship between DOM spectral parameters and antibiotic concentrations in the Yellow River basin. Specifically, r (C3, C2) was significantly and positively correlated with the concentrations of SMX, sulfadoxine (SDX), and ERY, while humification index (HIX) had an opposite relationship with these antibiotics. These results suggested that SMX, SDX and ERY were mainly discharged from wastewater treatment plants into the mainstream of the Yellow River. This work provides a powerful demonstration that DOM plays an important role in indicating the occurrence and sources of antibiotics in the aquatic environment.

Potential output and risk of commonly administered veterinary antibiotics from small-scale livestock farms to surrounding areas in Northwest China

The concern over antibiotic pollution from animal husbandry has significantly increased over recent years. However, few studies on output and environmental risk of veterinary antibiotics (VAs) throughout different exposure matrices from small-scale livestock farms (SSLFs) have been explored. This study explored the output and environmental risk of three classes of VAs (sulfonamides (SAs), tetracyclines (TCs), fluoroquinolones (FQs)) in three different types of environmental media (manure, soil, and plants/vegetables) derived from four livestock feedlots in the Hexi Corridor of Northwest China. Following, a risk assessment was conducted to identify the hazardous potential of these VAs on the ecological health of the surrounding environment. A total of 108 soil, 36 manure, 12 plants/vegetables, and 15 animal product samples were collected from the animal feedlots for analysis. The results showed that each of the three groups of VAs were detected in the soil, manure and plant samples derived from all four feedlots in varying levels. In the soil samples, the detection rate of SAs (68%) was higher than the TCs (57%) and the FQs (27%). The total concentration of VAs ranged from not detected (n.d.) to 275 ng/g, while chlortetracycline (CTC) was the most abundant (275 ng/g) of the VAs in soil samples. The SAs had the highest detection rate (100%), followed by TCs (89%), and FQs (78%) in manure samples. The total concentration of VAs residues ranged from n. d. to 105 ng/g, of which CTC was as high as 91 ng/g in manures. In the plant/vegetable samples, the TCs had the highest detection rate (58%), while sulfamethazine (SDM) was the most abundant (32 ng/g). The total concentration of the VAs ranged from n. d. to 65 ng/g in the plant/vegetable samples. The target VAs were not detected in animal products. Measurements of the composition of VAs in soil samples at different vertical depths as well as horizontal distances from the manure accumulation sites showed that VAs were partially retained in the soil of the feedlots and were distributed into the surrounding environment both horizontally and vertically. It is suspected that the detected VAs could be accumulated in agricultural soils since they could be found in most of the sampled manures and soils in SSLFs. These results highlighted the necessity of considering SSLF practices to mange the accumulation and disposal of manure mitigating and controlling VA pollution.

Occurrence and influencing factors of antibiotics and antibiotic resistance genes in sediments of the largest multi-habitat lakes in Northern China

Baiyangdian Lake is a typical and largest multi-habitat lake in the North plain of China. To understand the generation and transmission of antibiotics resistance genes (ARGs) in multi-habitat lakes, the contents of nutrients (TC, TOC, TN, TP and TS), heavy metals (Zn, Cr, Ni, Cu, Pb, As, Cd and Hg), 22 antibiotics, 16S-rRNA(16S), Class I integron (intI1) and 20 ARGs were determined. Samples were taken from the Fuhe river, river estuaries, reed marshes, living area, fish ponds and open water of Baiyangdian Lake. The results showed that quinolones were the main pollutants in six habitats, and the content range was ND-104.94 ng/g. Thereinto, aac (6') -IB, blaTEM-1, ermF, qnrA, qnrD, tetG, sul1, sul2 and tetM were detected in all the analyzed samples. The absolute abundance of sul1 was the highest (5.25 × 10⁵ copies/g-6.21 × 10⁷ copies/g) in most of the samples. In these different habitats, the abundance of antibiotics and ARGs in river estuary was the highest, and that in reed marshes was the lowest. There was a significant positive correlation between the abundance of heavy metals (Cu, Pb, Zn, Ni, Cd, Hg) and the absolute abundance of 11 ARGs (P < 0.01). Redundancy analysis showed that Cu, Zn, intI1, TP and macrolides were the important factors affecting the distribution of ARGs. Our finding provides a more likely driving and influencing factor for the transmission of ARGs in lakes with complex and diverse habitats.