Chemical Fate and Partitioning Behavior of Antibiotics in the Aquatic Environment-A Review

Pollution by antimicrobials and antibiotic resistance genes in East Africa: Occurrence, sources, and potential environmental implications

The escalating burden of antimicrobial pollution in East Africa poses severe threats to public health, environmental integrity, and economic stability. Environmental compartments such as soil and water serve as reservoirs for these pollutants such as antimicrobials and antibiotic resistance genes, creating selective pressure that accelerates the emergence of antimicrobial resistance (AMR). These dynamic fosters the proliferation of multidrug-resistant pathogens, or "superbugs," complicating infection management and amplifying health risks in a region already challenged by inadequate healthcare and sanitation infrastructure. Furthermore, pollution by antimicrobials and antibiotic resistance genes critically disrupts ecological processes, such as nutrient cycling and organic matter degradation, diminishing soil fertility, water quality, and agricultural productivity, thereby threatening food security and overall ecological health. Current surveillance efforts, including the Global Antimicrobial Resistance and Use Surveillance System (GLASS) and the East Africa Public Health Laboratory Networking Project (EAPHLNP), have made strides in tracking AMR trends and guiding policy decisions. However, these efforts remain insufficient to address the growing crisis. This study highlights the urgent need for integrated strategies, including stringent antibiotic usage regulations, advanced wastewater treatment technologies, and comprehensive environmental surveillance. Therefore, there is a need to address the intersections of health, agriculture, and environment, to mitigate AMR and its far-reaching consequences to ensure public health safety and sustainability.

Tracking antibiotics and antibiotic-resistant E. coli in the aquatic environment linked to agriculture

The application of manure to fertilize agricultural land is associated with the introduction of antibiotic residues and bacteria, including antibiotic-resistant bacteria, which can reach surface water through runoff and drainage and groundwater through leaching from the soil. This was investigated by sampling 50 surface water locations (before and after fertilization) and 50 groundwater wells for the presence of antibiotic residues and the presence of antibiotic-resistant bacteria. For the latter, Escherichia coli and extended-spectrum β-lactamase (ESBL) producing E. coli were used as indicators and profiled for antibiotic resistance. The presence of a wide range of antibiotic residues, though at low concentrations (0.01-10 μg/L), in freshwater ecosystems highlights the extensive spread of these substances. Only 16 % of the samples were consistently free of antibiotic residues throughout both sampling periods. Notably, the frequent occurrence of sulfonamides and lincomycin in surface waters raises concerns as their concentrations occasionally exceed the predicted no-effect levels for antimicrobial resistance selection. Maximum concentrations were reported at 8.83 μg/L and 1.60 μg/L for sulfamethoxazole and lincomycin, respectively. Additionally, resistance patterns in E. coli indicate increased resistance to sulfamethoxazole following the fertilization period, suggesting that the application of manure on fields contributes to a rise in antibiotic resistance from 20 % to 48 %. Although antibiotic contamination in groundwater is less prevalent, antibiotic resistance remains widespread. In particular, ESBL-producing E. coli exhibit heightened resistance levels, not limited to β-lactam antibiotics. The detection of resistance to critical last-resort antibiotics such as carbapenems and colistin further emphasizes the urgency of addressing antibiotic resistance in environmental contexts. This study highlights the need for continued monitoring and the implementation of legislation to reduce antibiotic pollution and tackle resistance in aquatic ecosystems.

Key role of hydrodynamic conditions in the adsorption and migration of sulfamethoxazole driven by suspended particulate matter

The widespread use of sulfamethoxazole (SMX) has led to pervasive antibiotic contamination in aquatic environments, where suspended particulate matter (SPM) serves as a critical mediator in the retention, transport, and fate of antibiotic pollutants within riverine ecosystems. However, existing research predominantly emphasizes adsorption mechanisms under static batch equilibrium conditions, overlooking the dynamic interplay between SPM and antibiotics across hydrodynamic conditions regimes.Thus, the dynamic adsorption process of SMX on SPM was investigated through a series of annular flume experiments, and the MIKE 21 model was employed to simulate the migration of SMX and SPM. Results showed that the SMX adsorption amounts decreased significantly with increasing flow velocity, and the SMX desorption would occur when hydrodynamic conditions changed suddenly, especially for the continuous enhancement in velocity. As hydrodynamics stabilized, the re-adsorption of SMX would occur. The adsorption process of SMX was related with the property changes of SPM, and the enhancement of hydrodynamic conditions can significantly weaken the surface complexation between SPM and SMX, further resulting in a decrease in the SMX adsorption amounts. Meanwhile, high flow velocity would cause more obvious pore filling of SMX on SPM and led the clearer SMX adsorption fluctuations under the varying the hydrodynamic conditions. The MIKE 21 simulations identified that the continuous enhanced hydrodynamics significantly prolonged the interaction time between SMX and SPM, while the weak hydrodynamics and high SPM concentrations could particularly slow the SMX diffusion downstream.

Antibiotic Abuse in Ornamental Fish: An Overlooked Reservoir for Antibiotic Resistance

Ornamental fish represent a significant aquaculture sector with notable economic value, yet their contribution to antibiotic residues and resistance remains underrecognized. This review synthesizes evidence on widespread and often unregulated antibiotic use-including tetracyclines and fluoroquinolones-in ornamental fish production, transportation, and retail, primarily targeting bacterial diseases such as aeromonosis and vibriosis. Pathogenic microorganisms including Edwardsiella, Flavobacterium, and Shewanella spp. cause diseases like hemorrhagic septicemia, fin rot, skin ulcers, and exophthalmia, impairing fish health and marketability. Prophylactic and therapeutic antibiotic applications elevate antibiotic residues in fish tissues and carriage water, thereby selecting for antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs). These resistant elements pose significant risks to fish health, human exposure via direct contact and bioaerosols, and environmental health through contamination pathways. We emphasize the urgent need for a holistic One Health approach, involving enhanced surveillance, stringent regulatory oversight, and adoption of alternative antimicrobial strategies, such as probiotics and advanced water treatments. Coordinated global actions are crucial to effectively mitigate antibiotic resistance within the ornamental fish industry, ensuring sustainable production, safeguarding public health, and protecting environmental integrity.

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

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

Effect of 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.

Man-made emerging contaminants in the High-Arctic fjord Kongsfjorden (Svalbard Archipelago, Norway): Occurrence, sources and risk assessment

This study provides the first quantitative data on the presence of 17 pharmaceuticals and personal care products (PPCPs) from various therapeutical classes in surface seawater from Kongsfjorden (KF, Svalbard Archipelago, Norway, 79°00'N, 11°40'E), collected over five summers (2018-2022). The PPCPs (ciprofloxacin-CIP, enrofloxacin-ENR, amoxicillin-AMX, erythromycin-ERY, sulfamethoxazole-SMX, N4-acetylsulfamethoxazole-N4-SMX, carbamazepine-CBZ, diclofenac-DCF, ibuprofen-IBU, acetylsalicylic acid-ASP, paracetamol-PAR, caffeine-CFF, triclosan-TCL, N,N-diethyl-meta-toluamide-DEET, estrone-E1, 17β-estradiol-E2 and 17α-ethinyl estradiol-EE2) were also analysed in sewage from the wastewater treatment plant, serving Ny-Ålesund, located on KF's southern shore. Samples were processed using solid phase extraction and liquid chromatography with high-resolution mass-spectrometry. An environmental risk assessment (ERA) was conducted to evaluate ecological and antimicrobial resistance (AMR) risks and the cumulative risk from the chemical mixture. PPCPs detected in sewage were also found in seawater, with the highest concentrations in sewage for CFF (151.9 ± 8.7 ng/L) and ASP (122.5 ± 9.4 ng/L). In seawater, the main contributors were ASP (39.2 ± 12.9 ng/L) and EE2 (32.5 ± 11.9 ng/L), suggesting influences from local emissions, fjord circulation, and broader oceanic and atmospheric transport. The ERA identified CIP, DCF, IBU, CFF, TCL, E1, E2 and EE2 as potentially harmful to the Arctic marine ecosystem. When evaluated as a mixture, all compounds contributed additively to the overall risk. The AMR risk from the antibiotic ciprofloxacin was found to be low. These findings emphasize the need for enhanced monitoring of PPCPs and comprehensive ERAs of chemical mixtures to guide management strategies and protect sensitive Arctic ecosystems.

Influence of soil type on bacterial growth and tolerance to experimentally added human antibiotics

The human antibiotics cefuroxime (CXM) and azithromycin (AZI) are among the most commonly prescribed. A significant portion of both are excreted and has been detected in sewage treatment plant effluents. The increasing use of such effluents in crops for irrigation and as fertilisers poses a threat to soil microbiota because of the presence of antibiotics. The lack of studies on CXM and AZI in soils hinders our understanding of their potential toxic effects on soil bacterial communities and ecosystem services. This study significantly contributes to the literature by quantifying the toxicity of CXM and AZI at varying concentrations in 12 different crop soils and tracking their evolution over time. The study also examined whether antibiotic pressure led to the development of more tolerant bacterial communities. The results of this study are the values of the logarithm of the antibiotic concentration at which 50 % of bacterial growth is inhibited (Log IC50) and indicate that both antibiotics are toxic to soil bacteria. The direct toxicity of CXM (1 day after contamination) was higher (Log IC50: 0.9 = 7.9 mg kg-1) than that of AZI (Log IC50: 3.4 = 2362 mg kg-1). However, bacterial growth was less affected by CXM over time, whereas AZI remained toxic in some soils until day 42 (Log IC50: 3.2 = 1533 mg kg-1 and 3.4 = 2291 mg kg-1, respectively). The overall results indicate that selective pressure exerted by antibiotics generates antibiotic tolerance in soils, even at the lowest antibiotic concentration studied (7.8 mg kg-1). The general trend was to increase tolerance to higher antibiotic concentrations up to the highest concentration studied (2000 mg kg-1). However, the degree of tolerance developed was highly dependent on soil type. More studies should be conducted to quantitatively assess the toxic and tolerance-developing effects of antibiotics in soils. Such information will be valuable for identifying which antibiotics pose a threat to the soil microbiota and consequently to human health.

Pollution of Soil by Pharmaceuticals: Implications for Metazoan and Environmental Health

The use of pharmaceuticals has grown substantially and their consequential release via wastewaters poses a potential threat to aquatic and terrestrial environments. While transportation prediction models for aquatic environments are well established, they cannot be universally extrapolated to terrestrial systems. Pharmaceuticals and their metabolites are, for example, readily detected in the excreta of terrestrial organisms (including humans). Furthermore, the trophic transfer of pharmaceuticals to and from food webs is often overlooked, which in turn highlights a public health concern and emphasizes the pressing need to elucidate how today's potpourri of pharmaceuticals affect the terrestrial system, their biophysical behaviors, and their interactions with soil metazoans. This review explores the existing knowledge base of pharmaceutical exposure sources, mobility, persistence, (bio)availability, (bio)accumulation, (bio)magnification, and trophic transfer of pharmaceuticals through the soil and terrestrial food chains.

Mapping the risk of ciprofloxacin in European water bodies: Incorporating the impact of bioavailability

Widespread use of ciprofloxacin (CIP) in surface waters has raised ecological and human health concerns. However, the measured environmental concentration (MEC) of CIP may not directly indicate its ecological impact because CIP bioavailability and thus toxicity are influenced by environmental factors, such as pH and dissolved organic carbon (DOC). The present study integrates CIP toxicity as a function of pH and DOC into an environmental risk assessment (ERA) of CIP in European surface waters. A bioavailability model and water quality databases were used to estimate the predicted no-effect concentration (PNECECO) of CIP to protect freshwater ecosystems under five ERA scenarios. PNECECO values were predicted following the European Medicines Agency guidelines using ecotoxicity data for the cyanobacterium Microcystis aeruginosa, identified as the freshwater species most sensitive to CIP. The PNECECO values predicted under Scenarios 1 (not considering bioavailability) and 2 (assuming the most bioavailable form of CIP, the zwitterion CIP+/- at maximum relative abundance) were 25 ng L-1 and 32 ng L-1, respectively. Including the bioavailability effect of pH in Scenario 3 resulted in a range of PNECECO values from 25.0 to 62.4 ng L-1 (across Europe) whereas further including weak (Scenario 4) and strong (Scenario 5) CIP-DOC binding led to larger regional variations in PNECECO (25.8-1207 ng L-1). The PNECECO values were combined in Monte Carlo simulations with MEC data for the CIP to assess the probabilities of unacceptable risk (PUR), uncertain risk (PUN), and acceptable risk (PAR) for Europe and for ten countries. The EU-wide PUR values (9.8 %-22.0 %) were unrepresentative of individual countries (0 %-99 %), while variations in PUR across scenarios (0 %-95 %) indicated different influences of pH and DOC by country. Overall, DOC has a stronger impact than pH on the predicted no-effect concentrations (PNECs) and on the ecological risk of CIP, and thus the consideration of bioavailability can greatly improve the environmental relevance of the ERA outcomes.

Effectiveness of Cooking Procedures in Reducing Antibiotic Residues in Bivalves

Background/Objectives: The widespread use of antibiotics, which wastewater treatment plants (WWTPs) cannot fully remove, in human and veterinary medicine leads to their release into wastewater, resulting in the contamination of aquatic environments. Bivalves can accumulate these antibiotics, posing a risk to shellfish consumers, including potential antimicrobial resistance. This study aimed to assess how three cooking methods-marinating, steaming, and grilling-affect the concentration of 33 different antibiotics in bivalves fortified at the level of maximum residue limit (MRL) and twice the MRL (2MRL). Results: The data show the percentage of antibiotic remaining after cooking: 100% indicates stability or no reduction; values above 100% show an increase in concentration, and values below 100% reflect a decrease in antibiotic concentration. In general, all culinary procedures removed part of the added antibiotics. However, the most effective method was marinating (47%), followed by steaming (60%) and finally grilling (92%). It was also found that, overall, the fortification level, MRL or 2MRL, did not impact antibiotic removal in each cooking method. Moreover, different antibiotics' classes presented diverse removals when cooked, ranging between 0% for penicillins and 73% for sulphonamides. Furthermore, the results showed a great diversity of responses to cooking within some antibiotic classes. Methods: After cooking, the analysis was based on solid-liquid extraction followed by liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-ToF-MS). Conclusions: The ongoing monitoring of antibiotic levels is essential, and further research is needed to understand how cooking affects these substances and their metabolites. This will help assess the real risk to consumers and guide risk-mitigation measures.

Metabolic variation and oxidative stress responses of clams (Ruditapes philippinarum) perturbed by ofloxacin exposure

Ofloxacin (OFL), one of the most widely used fluoroquinolone antibiotics, has been frequently detected in marine environments. Nonetheless, researchers are yet to focus on the effects of OFL on the benthos. In the present study, marine clams (Ruditapes philippinarum) were exposed to OFL (0.5, 50, and 500 μg/L) for 14 d, followed by a 7 d depuration period. The accumulation of OFL, antioxidative defense responses, neurotoxicity, burrowing behavior, and metabolomic changes in clams were evaluated. The results indicated that OFL could accumulate in clams, albeit with a low bioaccumulation capacity. The intermediate (50 μg/L) and high (500 μg/L) levels of OFL induced significant antioxidative responses in the gills and digestive glands of clams, mainly manifesting as the inhibition of catalase activities and the induction of superoxide dismutase and glutathione S-transferase activities, which ultimately elevated the content of malondialdehyde, causing oxidative damage. Furthermore, the significant induction of acetylcholinesterase activities was observed, coinciding with a significant increase in burrowing rates of clams. The high level of OFL affected glycerophospholipid, arachidonic acid, steroid hormone biosynthesis, unsaturated fatty acids biosynthesis, and glycolysis/glycogenesis metabolism. In conclusion, this study has contributed to the understanding of the physiological and biochemical effects and molecular toxicity mechanisms of OFL to marine bivalves.

Swine wastewater co-exposed with veterinary antibiotics enhanced the antibiotic resistance of endophytes in radish (Raphanus sativus L.)

The widespread utilization of antibiotics in livestock has promoted the accumulation and diffusion of antibiotics and antibiotic resistance in agricultural soils and crops. Here we investigated the mechanisms of antibiotic uptake and accumulation in swine wastewater (SW)-treated radish (Raphanus sativus L.) and subsequent impacts on endophyte antibiotic resistance. Under SW treatments, exposure to 500 μg/L sulfamethazine (SMZ) and enrofloxacin (EFX) significantly affected radish biomass, with SMZ causing 63.0% increases and EFX causing 36.3% decreases relative to the untreated control. EFX uptake by radish were from 5 to 100-folds over SMZ. Passive diffusion through anion channel proteins on cell membranes was an important route for SMZ uptake, while both passive diffusion and energy-dependent processes contributed to the uptake of EFX. Bacterial community was time-dependent as a function of both antibiotics and SW, the bacterial alpha diversity in liquid solution co-treated with antibiotics and SW increased over time. The abundance of antibiotic resistance genes (ARGs) in the roots was positively correlated with ARGs in the Hoagland's solution under antibiotic-alone treatments. EFX co-exposure with SW enhanced the dissemination of ARGs from swine wastewater into plant roots, and significant correlations existed between ARGs and integrons in both Hoagland's solution and roots. These findings increased our understanding of the fate of antibiotics in crops and their subsequent impacts on antibiotic resistance of endophytic bacteria.

Antibiotic residues in the cirata reservoir, Indonesia and their effect on ecology and the selection for antibiotic-resistant bacteria

Antibiotic residues, their mixture toxicity, and the potential selection for antibiotic-resistant bacteria could pose a problem for water use and the ecosystem of reservoirs. This study aims to provide a comprehensive understanding of the occurrence, concentration, distribution, and ecological risks associated with various antibiotics in the Cirata reservoir, Indonesia. In our water and sediment samples, we detected 24 out of the 65 antibiotic residues analyzed, revealing a diverse range of antibiotic classes present. Notably, sulphonamides, diaminopyrimidine, and lincosamides were frequently found in the water, while the sediment predominantly contained tetracyclines and fluoroquinolones. Most antibiotic classes reached their highest concentrations in the water during the dry season. However, fluoroquinolones and tetracyclines showed their highest concentrations in the water during the wet season. Ecotoxicological risk assessments indicated that the impact of most antibiotic residues on aquatic organisms was negligible, except for fluoroquinolones. Looking at the impact on cyanobacteria, however, varying risks were indicated, ranging from medium to critical, with antibiotics like sulfamethoxazole, ciprofloxacin, norfloxacin, and lincomycin posing substantial threats. Among these, ciprofloxacin emerged as the antibiotic with the strongest risk. Furthermore, fluoroquinolones may have the potential to contribute to the selection of antibiotic-resistant bacteria. The presence of mixtures of antibiotic residues during the wet season significantly impacted species loss, with Potentially Affected Fraction of Species (msPAF) values exceeding 0.75 in almost 90% of locations. However, the impact of mixtures of antibiotic residues in sediment remained consistently low across all locations and seasons. Based on their occurrences and associated risks, 12 priority antibiotic residues were identified for monitoring in the reservoir and its tributaries. Moreover, the study suggests that river inflow serves as the most significant source of antibiotic residues in the reservoir. Further investigations into the relative share attribution of antibiotic sources in the reservoir is recommended to help identify effective interventions.

Analysis of interactions between pharmaceuticals and humic acid: Characterization using entrapment and high-performance affinity microcolumns

The presence of pharmaceuticals as microcontaminants in the environment has become of particular concern given the growing increase in water reuse and recycling to promote global sustainability of this resource. Pharmaceuticals can often undergo reversible interactions with soluble dissolved organic material such as humic acid, which may be an important factor in determining the bioavailability and effects of these compounds in the environment. In this study, high-performance affinity microcolumns containing non-covalently entrapped and immobilized humic acid are used to examine the binding strength and interactions of this agent for tetracycline, carbamazepine, ciprofloxacin, and norfloxacin, all common pharmaceutical microcontaminants known to bind humic acid. The binding constants, as measured with Aldrich humic acid, have good agreement with values reported in the literature. In addition, the effects of temperature, ionic strength, and pH on these interactions are examined with the humic acid microcolumns. This technique makes it possible to determine the relative importance of electrostatic interactions vs non-polar interactions or hydrogen bonding on these binding processes. This study illustrates how affinity microcolumns can be used to screen and uniformly quantify binding by pharmaceuticals with humic acid, as well as to study the mechanisms of these interactions, with this information often being acquired in minutes and with small amounts of binding agent (∼10 mg per microcolumn, which could be used over 200-300 experiments). Use of entrapment and affinity microcolumns can support similar research for a wide range of other microcontaminants with humic acid or alternative binding agents found in water and the environment.

Occurrence, dissipation kinetics and environmental risk assessment of antibiotics and their metabolites in agricultural soils

Antibiotics are among the emerging contaminants of greatest concern to the scientific community. However, the occurrence and behaviour of their metabolites in soils have been scarcely studied. To address this research gap, this study investigates the occurrence, sorption, dissipation kinetics, and environmental risk of highly important antibiotics (sulfamethazine, sulfadiazine, sulfamethoxazole, trimethoprim) and their main metabolites in Mediterranean agricultural soils. Batch experiments were conducted under natural conditions for 120 days. Five different dissipation kinetics models were applied to elucidate antibiotics degradation. The sorption isotherms were evaluated by three different models. Most of the antibiotics and metabolites tested showed a good fit with the Linear Isotherm model (R2 >0.96) and biphasic dissipation kinetic models (R2 >0.90). The dissipation and the endpoints values (DT50 and DT90) depended on the soil type properties. A Lixisol soil demonstrated reduced degradation of the investigated compounds. Trimethoprim showed the highest persistence, followed by sulfamethazine, sulfamethoxazole, and sulfadiazine. Parent compounds exhibited lower degradation rates than their metabolites. Remaining antibiotic concentrations were found to be below the predicted no-effect concentration in soil, suggesting that they may not pose a risk to terrestrial biota. This study provides valuable insights into the behaviour of these antibiotics and their metabolites in soil.

Thermodynamic Assessment of the Pyrazinamide Dissolution Process in Some Organic Solvents

Pyrazinamide is a first line drug used for the treatment of tuberculosis, a pathology that caused the death of more than 1.3 million people in the world during 2022, according to WHO, being a drug of current interest due to its relevance in pharmaceutical and medical sciences. In this context, solubility is one of the most important physicochemical parameters in the development and/or optimization of new pharmaceutical forms, so the present work aims to present a thermodynamic study of the solubility of pyrazinamide in nine organic solvents of pharmaceutical interest. Using the shake-flask method and UV/Vis spectrophotometry, the solubility of this drug was determined at 9 temperatures; the maximum solubility was obtained in dimethyl sulfoxide at 318.15 K (x2=0.0816±0.004) and the minimum in cyclohexane at 283.15 K (1.73±0.05×10-5). From the apparent solubility data, the thermodynamic functions of solution and mixing were calculated, indicating an endothermic process. In addition, the solubility parameter of pyrazinamide was calculated using the Hoftyzer-van Krevelen (32.90 MPa1/2) and Bustamante (28.14 MPa1/2) methods. The maximum solubility was reached in dimethyl sulfoxide and the minimum in cyclohexane. As for the thermodynamic functions, the entropy drives the solution process in all cases. In relation to the solubility parameter, it can be analyzed that the mathematical models offer approximations; however, the experimental data are still primordial at the time of inferring any process.

Electrospun Nanofiber Dopped with TiO2 and Carbon Quantum Dots for the Photocatalytic Degradation of Antibiotics

Novel photocatalysts were synthesized through the association of carbon quantum dots (CQDs) with commercial (P25) titanium dioxide (TiO2) by sonication. The resulting TiO2/CQDs composite was then incorporated into the polyamide 66 (PA66) biopolymer nanofibers using the electrospinning technique, considering a composite nanoparticles-to-polymer ratio of 1:2 in the electrospinning precursor solution. The produced nanofibers presented suitable morphology and were tested for the photocatalytic degradation under simulated solar radiation of 10 mg L-1 of amoxicillin (AMX) and sulfadiazine (SDZ), in phosphate buffer solution (pH 8.06) and river water, using 1.5 g L-1 of photocatalyst. The presence of the photocatalyst increased the removal of AMX in phosphate buffer solution by 30 times, reducing the AMX degradation half-life time from 62 ± 1 h (without catalyst) to 1.98 ± 0.06 h. Moreover, SDZ degradation half-life time in phosphate buffer solution was reduced from 5.4 ± 0.1 h (without catalyst) to 1.87 ± 0.05 h in the presence of the photocatalyst. Furthermore, the PA66/TiO2/CQDs were also efficient in river water samples and maintained their performance in at least three cycles of SDZ photodegradation in river water. The presented results evidence that the produced photocatalyst can be a promising and sustainable solution for antibiotics' efficient removal from water.

The behavior of pharmaceutically active compounds and contrast agents during wastewater treatment - Combining sampling strategies and analytical techniques: A critical review

Increasing consumption of pharmaceuticals and the respective consequences for the aquatic environment have been the focus of many studies over the last thirty years. Various aspects in this field were investigated, considering diverse pharmaceutical groups and employing a wide range of research methodologies. Various questions from the perspectives of different research areas were devised and answered, resulting in a large mix of individual findings and conclusions. Collectively, the results of the studies offer a comprehensive overview. The large variety of methods and strategies, however, demands close attention when comparing and combining information from heterogeneous projects. This review critically examines the application of diverse sampling techniques as well as analytical methods in investigations concerning the behavior of pharmaceutically active compounds (PhACs) and contrast agents (CAs) in wastewater treatment plants (WWTPs). The combination of sampling and analysis is discussed with regard to its suitability for specific scientific problems. Different research focuses need different methods and answer different questions. An overview of studies dealing with the fate and degradation of PhACs and CAs in WWTPs is presented, discussing their strategic approaches and findings. This review includes surveys of anticancer drugs, antibiotics, analgesics and anti-inflammatory drugs, antidiabetics, beta blockers, hormonal contraceptives, lipid lowering agents, antidepressants as well as contrast agents for X-ray and magnetic resonance imaging.

Experimentally derived partitioning coefficients of carbamazepine and sulfadiazine in landfill refuse-leachate phase: Effects of refuse and leachate properties

Pharmaceuticals have been detected at high concentrations in landfill leachate and refuse, which may pose potential long-term environmental impacts. The interaction of pharmaceuticals between leachate and refuse contributes to their retention through in situ sorption, thereby mitigating this impact. However, limited efforts have been made to describe the distribution characteristics of pharmaceuticals in the refuse-leachate phase. In this study, two refuse and three leachate samples were used to obtain partitioning coefficients (Kd) for two typical pharmaceuticals, carbamazepine (CBZ) and sulfadiazine (SD), with campus soil as a comparison. Landfill refuse exhibited higher Kd values (12.36 ± 0.90 and 19.76 ± 1.96 mL/g for CBZ and 1.90 ± 0.34 and 6.27 ± 0.58 mL/g for SD in two samples, respectively) than campus soil (3.73 ± 1.31 mL/g for CBZ and 0.81 ± 0.26 mL/g for SD), influenced by refuse properties such as higher organic matter (OM) content and specific surface area (SSA). The influence of leachate pH on Kd values depended on the electrostatic interaction between the species of target pollutants and negatively charged refuse. The effect of humic acid (HA) was related to its binding with target pollutants in solution and its competition with them for sorption sites. Electrostatic repulsion, hydrogen bonding and π-π interaction were the proposed mechanisms in SD sorption on refuse, while hydrogen bonding participated in the sorption of CBZ. The results will help aid the understanding of the distribution of pharmaceuticals in the refuse-leachate system and improve corresponding management strategies.

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.

Antibiotic Residues and Resistance in Three Wastewater Treatment Plants in Romania

This study evaluates antibiotic residues and bacterial loads in influent and effluent samples from three wastewater treatment plants (WWTPs) in Romania, across four seasons from 2021 to 2022. Analytical methods included solid-phase extraction and high-performance liquid chromatography (HPLC) to quantify antibiotic concentrations, while microbiological assays estimated bacterial loads and assessed antibiotic resistance patterns. Statistical analyses explored the impact of environmental factors such as temperature and rainfall on antibiotic levels. The results showed significant seasonal variations, with higher antibiotic concentrations in warmer seasons. Antibiotic removal efficiency varied among WWTPs, with some antibiotics being effectively removed and others persisting in the effluent, posing high environmental risks and potential for antibiotic resistance development. Bacterial loads were higher in spring and summer, correlating with increased temperatures. Eight bacterial strains were isolated, with higher resistance during warmer seasons, particularly to amoxicillin and clarithromycin.

A waste-to-wealth conversion of plastic bottles into effective carbon-based adsorbents for removal of tetracycline antibiotic from water

Currently, plastic waste and antibiotic wastewater are two of the most critical environmental problems, calling for urgent measures to take. A waste-to-wealth strategy for the conversion of polyethylene terephthalate (PET) plastic bottles into value-added materials such as carbon composite is highly recommended to clean wastewater contaminated by antibiotics. Inspired by this idea, we develop a novel PET-AC-ZFO composite by incorporating PET plastic-derived KOH-activated carbon (AC) with ZnFe2O4 (ZFO) particles for adsorptive removal of tetracycline (TTC). PET-derived carbon (PET-C), KOH-activated PET-derived carbon (PET-AC), and PET-AC-ZFO were characterized using physicochemical analyses. Central composite design (CCD) was used to obtain a quadratic model by TTC concentration (K), adsorbent dosage (L), and pH (M). PET-AC-ZFO possessed micropores (d ≈ 2 nm) and exceptionally high surface area of 1110 m2 g-1. Nearly 90% TTC could be removed by PET-AC-ZFO composite. Bangham kinetic and Langmuir isotherm were two most fitted models. Theoretical maximum TTC adsorption capacity was 45.1 mg g-1. This study suggested the role of hydrogen bonds, pore-filling interactions, and π-π interactions as the main interactions of the adsorption process. Thus, a strategy for conversion of PET bottles into PET-AC-ZFO can contribute to both plastic recycling and antibiotic wastewater mitigation.

Sorption of ciprofloxacin and enrofloxacin on alkaline cropland soil in semiarid regions: Roles of pH, ionic strength, and ion type

Animals manure and chemical fertilizers are widely applied to agricultural soils to mitigate soil fertility decline resulting from intensive farming practices. However, the use of antibiotics such as ciprofloxacin (CIP) and enrofloxacin (ENR) in these manures introduces certain environmental risks. The sorption of CIP and ENR in soil is influenced by various factors. Soil cations (i.e., Na+, K+, Mg2+, and Ca2+) and artificially introduced ions (NH4+) can affect the sorption behavior of CIP and ENR in alkaline agricultural soils through mechanisms such as ion exchange and competitive sorption. To investigate the effects of ionic strength and ion type on the sorption of antibiotics in alkaline agricultural soil, batch equilibrium experiments were conducted in this study. The results showed that the affinity of alkaline farmland soil to CIP and ENR was poor, and Kd was only 159 L/kg and 89 L/kg, respectively. Increases in temperature and pH inhibited CIP and ENR sorption on soil. Mineral elements in the soil strongly inhibited CIP and ENR sorption. Conversely, NH4+ promoted the Kd values of CIP and ENR by 46% and 221%, respectively. Additionally, under different influencing factors, both the sorption affinity (Kd) and sorption amount of ENR were lower than those of CIP. These findings indicate that ENR has a greater migration potential and poses a greater environmental risk in agricultural soils. Alkaline soil and mineral elements increase the migration potential of CIP, ENR, but the introduction of NH4+ in agricultural production can weaken the migration potential of them.

Review on antibiotic pollution dynamics: insights to occurrence, environmental behaviour, ecotoxicity, and management strategies

Antibiotic contamination poses a significant global concern due to its far-reaching impact on public health and the environment. This comprehensive review delves into the prevalence of various antibiotic classes in environmental pollution and their interactions with natural ecosystems. Fluoroquinolones, macrolides, tetracyclines, and sulphonamides have emerged as prevalent contaminants in environmental matrices worldwide. The concentrations of these antibiotics vary across diverse environments, influenced by production practices, consumer behaviours, and socio-economic factors. Low- and low-middle-income countries face unique challenges in managing antibiotic contamination, with dominant mechanisms like hydrolysis, sorption, and biodegradation leading to the formation of toxic byproducts. Ecotoxicity reports reveal the detrimental effects of these byproducts on aquatic and terrestrial ecosystems, further emphasizing the gravity of the issue. Notably, monitoring the antibiotic parent compound alone may be inadequate for framing effective control and management strategies for antibiotic pollution. This review underscores the imperative of a comprehensive, multi-sectoral approach to address environmental antibiotic contamination and combat antimicrobial resistance. It also advocates for the development and implementation of tailored national action plans that consider specific environmental conditions and factors. Thus, an approach is crucial for safeguarding both public health and the delicate balance of our natural ecosystems.

The Role of Wastewater Treatment Plants in Dissemination of Antibiotic Resistance: Source, Measurement, Removal and Risk Assessment

Antibiotic Resistance Genes (ARGs) are contaminants of emerging concern with marked potential to impact public and environmental health. This review focusses on factors that influence the presence, abundance, and dissemination of ARGs within Wastewater Treatment Plants (WWTPs) and associated effluents. Antibiotic-Resistant Bacteria (ARB) and ARGs have been detected in the influent and the effluent of WWTPs worldwide. Different levels of wastewater treatment (primary, secondary, and tertiary) show different degrees of removal efficiency of ARGs, with further differences being observed when ARGs are captured as intracellular or extracellular forms. Furthermore, routinely used molecular methodologies such as quantitative polymerase chain reaction or whole genome sequencing may also vary in resistome identification and in quantifying ARG removal efficiencies from WWTP effluents. Additionally, we provide an overview of the One Health risk assessment framework, as well as future strategies on how WWTPs can be assessed for environmental and public health impact.

From wastewater to clean water: Recent advances on the removal of metronidazole, ciprofloxacin, and sulfamethoxazole antibiotics from water through adsorption and advanced oxidation processes (AOPs)

Antibiotics released into water sources pose significant risks to both human health and the environment. This comprehensive review meticulously examines the ecotoxicological impacts of three prevalent antibiotics-ciprofloxacin, metronidazole, and sulfamethoxazole-on the ecosystems. Within this framework, our primary focus revolves around the key remediation technologies: adsorption and advanced oxidation processes (AOPs). In this context, an array of adsorbents is explored, spanning diverse classes such as biomass-derived biosorbents, graphene-based adsorbents, MXene-based adsorbents, silica gels, carbon nanotubes, carbon-based adsorbents, metal-organic frameworks (MOFs), carbon nanofibers, biochar, metal oxides, and nanocomposites. On the flip side, the review meticulously examines the main AOPs widely employed in water treatment. This includes a thorough analysis of ozonation (O3), the photo-Fenton process, UV/hydrogen peroxide (UV/H2O2), TiO2 photocatalysis, ozone/UV (O3/UV), radiation-induced AOPs, and sonolysis. Furthermore, the review provides in-depth insights into equilibrium isotherm and kinetic models as well as prospects and challenges inherent in these cutting-edge processes. By doing so, this review aims to empower readers with a profound understanding, enabling them to determine research gaps and pioneer innovative treatment methodologies for water contaminated with antibiotics.

Phthalic acid esters: Are they a big concern for rivers flowing into reservoir with ecological facilities?

The city-river-reservoir system is an important system for safeguarding drinking water. Phthalic acid esters (PAEs) are emerging contaminants in drinking water sources that are gaining attention, and they could pose risks to human health and aquatic organisms. In this study, field studies that lasted four years were conducted to analyze the concentrations, spatial-temporal distribution, and removal effects of six PAEs. The total concentrations of the Σ6PAEs in the water and sediment samples were 0.2-7.4 μg L-1 (mean: 1.3 μg L-1) and 9.2-9594.1 ng g-1 (mean: 847.5 ng g-1), respectively. Di-n-butyl phthalate (DBP) and, bis(2-ethylhexyl) phthalate (DEHP) were the predominant congeners, accounting for 57.2 % in the water samples and 94.1 % in the sediment samples. The urban area contributed 72 % of the PAEs in the system. A significant removal effect of PAEs was observed in the wetland, with a removal rate of 40.2 %. The partitioning of PAEs between the water and sediment was attributed to the removal of dimethyl phthalate and diethyl phthalate that occurred during the water phase, while the removal of DBP and DEHP primarily occurred during the sediment phase. The ecological risk calculation based on the sensitivity distribution model indicated that DBP (HQwater = 0.19, HQsediment = 0.46) and DEHP (HQwater = 0.20, HQsediment = 0.13) possessed moderate risks according to some water and sediment samples. The ecological projects were verified to be effective engineering strategies to reduce ecological risk in the drinking water source.

Submerged plant-biochar composite system exhibits effective control over residual organic pollutants in the benthic organisms of aquaculture ponds

As of now, submerged plants and biochar have demonstrated significant benefits in aquaculture pond sediment remediation. However, there is limited research on the synergistic effects of biochar and submerged plants in mitigating hydrophobic organic contaminant (HOC) accumulation in aquaculture benthic organisms and in controlling the nutrient (nitrogen and phosphorus) levels in aquaculture water. This study assesses a submerged plant-biochar system's efficacy in removing HOCs from simulated freshwater aquaculture ponds. Vallisneria natans was planted in sediment with varying levels of wheat straw biochar, while Corbicula fluminea served as the targeted benthic organism. The bioaccumulation experiment identified the optimal biochar ratio for the Vallisneria natans-biochar system in controlling HOCs in aquaculture products. Analyses included final accumulation concentrations in benthic organisms, changes in freely-dissolved concentrations in aquaculture sediment, and a mass balance calculation to explore key factors in their removal from the system. Results indicated that the Vallisneria natans-1.5% biochar composite system achieved optimal control of HOCs in sediment and aquaculture products. Biochar addition to the sediment in the composite system demonstrated a "promotion with low addition, inhibition with high addition" effect on Vallisneria natans growth. Notably, the addition of 1.5% biochar (VN1.5 group) significantly promoted the growth of Vallisneria natans leaves and roots. Comparing the final pollutant proportions in different environmental media, concentrations in water (0.20%-1.8%), clam accumulation (0.032%-0.11%), and plant absorption (0.10%-0.44%) constituted a minimal portion of the overall pollutant load in the system. The majority of pollutants (24%-65%) were degraded in the aquaculture environment, with microbial degradation likely playing a predominant role. Bacterial phyla, particularly Proteobacteria and Firmicutes, were identified as potential direct contributors to pollutant degradation in the Vallisneria natans-biochar system.

When antibiotics encounter microplastics in aquatic environments: Interaction, combined toxicity, and risk assessments

Antibiotics and microplastics (MPs), known as emerging pollutants, are bound to coexist in aquatic environments due to their widespread distribution and prolonged persistence. To date, few systematic summaries are available for the interaction between MPs and antibiotics in aquatic ecosystems, and a comprehensive reanalysis of their combined toxicity is also needed. Based on the collected published data, we have analyzed the source and distribution of MPs and antibiotics in global aquatic environments, finding their coexistence occurs in a lot of study sites. Accordingly, the presence of MPs can directly alter the environmental behavior of antibiotics. The main influencing factors of interaction between antibiotics and MPs have been summarized in terms of the characteristics of MPs and antibiotics, as well as the environmental factors. Then, we have conducted a meta-analysis to evaluate the combined toxicity of antibiotics and MPs on aquatic organisms and the related toxicity indicators, suggesting a significant adverse effect on algae, and inapparent on fish and daphnia. Finally, the environmental risk assessments for antibiotics and MPs were discussed, but unfortunately the standardized methodology for the risk assessment of MPs is still challenging, let alone assessment for their combined toxicity. This review provides insights into the interactions and environment risks of antibiotics and MPs in the aquatic environment, and suggests perspectives for future research.

Occurrence, bioaccumulation, fate, and risk assessment of emerging pollutants in aquatic environments: A review

Significant concerns on a global scale have been raised in response to the potential adverse impacts of emerging pollutants (EPs) on aquatic creatures. We have carefully reviewed relevant research over the past 10 years. The study focuses on five typical EPs: pharmaceuticals and personal care products (PPCPs), per- and polyfluoroalkyl substances (PFASs), drinking water disinfection byproducts (DBPs), brominated flame retardants (BFRs), and microplastics (MPs). The presence of EPs in the global aquatic environment is source-dependent, with wastewater treatment plants being the main source of EPs. Multiple studies have consistently shown that the final destination of most EPs in the water environment is sludge and sediment. Simultaneously, a number of EPs, such as PFASs, MPs, and BFRs, have long-term environmental transport potential. Some EPs exhibit notable tendencies towards bioaccumulation and biomagnification, while others pose challenges in terms of their degradation within both biological and abiotic treatment processes. The results showed that, in most cases, the ecological risk of EPs in aquatic environments was low, possibly due to potential dilution and degradation. Future research topics should include adding EPs detection items for the aquatic environment, combining pollution, and updating prediction models.

Adsorption, natural attenuation, and microbial community response of ofloxacin and oxolinic acid in marine sediments

The pollution of quinolone antibiotics in the marine environment has attracted widespread attention, especially for ofloxacin (OFL) and oxolinic acid (OXO) due to their frequent detection. However, few studies have been conducted to assess the behaviors and microbial community response to these antibiotics in marine sediments, particularly for potential antibiotic-resistant bacteria. In this work, the adsorption characteristics, natural attenuation characteristics, and variation of microbial communities of OFL and OXO in marine sediments were investigated. The adsorption process of antibiotics in sediments occurred on the surface and internal pores of organic matter, where OFL was more likely to be transferred from seawater to sediment compared with OXO. Besides, the adsorption of two antibiotics on sediment surfaces was attributed to physisorption (pore filling, electrostatic interaction) and chemisorption (hydrogen bonding). The natural attenuation of OFL and OXO in marine sediment followed second-order reaction kinetics with half-lives of 6.02 and 26.71 days, respectively, wherein biodegradation contributed the most to attenuation, followed by photolysis. Microbial community structure in marine sediments exposure to antibiotics varied by reducing abundance and diversity of microbial communities, as a whole displaying as an increase in the relative abundance of Firmicutes whereas a decrease of Proteobacteria. In detail, Escherichia-Shigella sp., Blautia sp., Bifidobacterium sp., and Bacillus sp. were those antibiotic-resistant bacteria with potential ability to degrade OFL, while Bacillus sp. may be resistant to OXO. Furthermore, functional predictions indicated that the microbial communities in sediment may resist the stress caused by OFL and OXO through cyano-amino acid metabolism, and ascorbate and aldarate metabolism, respectively. The research is key to understanding fate and bacterial resistance of antibiotics in marine sediments.

Efficient removal of tetracycline hydrochloride through novel Fe/BiOBr/Bi2WO6 photocatalyst prepared by dual-strategy under visible-light irradiation

It is important to investigate whether combining two modification strategies has a synergistic effect on the activity of photocatalysts. In this manuscript, Fe-doped BiOBr/Bi2WO6 heterojunctions were synthesized by a one-pot solvothermal method, and excellent photocatalytic performance was obtained for the degradation of tetracycline hydrochloride (TCH) in water without the addition of surfactant. Combining experiments and characterization, the synergistic effect between Fe ion doping and the BiOBr/Bi2WO6 heterojunction was elucidated. The Fe/BiOBr/Bi2WO6 composite photocatalyst had a beneficial void structure, enhanced visible light response, and could inhibit the recombination of photogenerated support well, which improved the photocatalytic activity. The presented experiments demonstrate that Fe/BiOBr/Bi2WO6 removes 97% of TCH from aqueous solution, while pure BiOBr and Bi2WO6 only remove 56% and 65% of TCH, respectively. Finally, the separation and transfer mechanisms of photoexcited carriers were determined in conjunction with the experimental results. This study provides a new direction for the design of efficient photocatalysts through the use of a dual co-modification strategy.

Aqueous fate of furaltadone: Kinetics, high-resolution mass spectrometry - based elucidation and toxicity assessment of photoproducts

Furaltadone (FTD) is an antibiotic belonging to the nitrofurans group. It has been broadly used in livestock and aquaculture for therapeutic purposes, as well as for stimulating promotion. Although the European Union has imposed restrictions on the use of FTD since 1995 due to concerns regarding its toxicity, in many cases FTD has been excessively and/or illegally applied in productive animals in developing countries, because of its high efficacy and low-cost. Unlike other nitrofuran compounds, the hydrolytic and photolytic behavior of FTD in natural aquatic systems has not been thoroughly investigated. To this end, hydrolysis in different pH values and photolysis in aquatic environment, including lake, river and sea water have been both examined. Hydrolysis was found to have an insignificant impact on degradation of FTD in the aquatic environment relevant pH values, whereas indirect photolysis proved to be the main route of its elimination. The identification of tentative photoproducts (PPs) was performed using ultra high performance liquid chromatography coupled to hybrid LTQ/Orbitrap high resolution mass spectrometry. A possible pathway for photolytic transformation of FTD was proposed. Additionally, in silico simulations were used to evaluate the toxicity such as the mutagenicity of FTD and PPs. Complementary to the low-cost and time-limited simulations, an in vitro method (Vibrio Fischeri bioluminescence) was also used to assess ecotoxicity.

Tetracyclines contamination in European aquatic environments: A comprehensive review of occurrence, fate, and removal techniques

Tetracyclines are among the most commonly used antibiotics for the treatment of bacterial infections and the improvement of agricultural growth and feed efficiency. All compounds in the group of tetracyclines (tetracycline, chlorotetracycline, doxycycline, and oxytetracycline) are excreted in an unchanged form in urine at a rate of more than 70%. They enter the aquatic environment in altered and unaltered forms which affect aquatic micro- and macroorganisms. This study reviews the occurrence, fate, and removal techniques of tetracycline contamination in Europe. The average level of tetracycline contamination in water ranged from 0 to 20 ng/L. However, data regarding environmental contamination by tetracyclines are still insufficient. Despite the constant presence and impact of tetracyclines in the environment, there are no legal restrictions regarding the discharge of tetracyclines into the aquatic environment. To address these challenges, various removal techniques, including advanced oxidation, adsorption, and UV treatment, are being critically evaluated and compared. The summarized data contributes to a better understanding of the current state of Europe's waters and provides insight into potential strategies for future environmental management and policy development. Further research on the pollution and effects of tetracyclines in aquatic environments is therefore required.

Urban agglomerations as an environmental dimension of antibiotics transmission through the "One Health" lens

The spatiotemporal distributions of antibiotics in different media have been widely reported; however, their occurrence in the environmental dimension of the Chinese urban agglomerations has received less attention, especially in bioaccumulation and health risks of antibiotics through the "One Health" lens. The review presents the current knowledge on the environmental occurrence, bioaccumulation, as well as health exposure risks in urban agglomerations through the "One Health" lens, and identifies current information gaps. The reviewed studies suggested antibiotic concentrations in water and soil were more sensitive to social indicators of urban agglomerations than those in sediment. The ecological risk and resistance risk of antibiotics in water were much higher than those of sediments, and the high-risk phenomenon occurred at a higher frequency in urban agglomerations. Erythromycin-H2O (ETM-H2O), amoxicillin (AMOX) and norfloxacin (NFC) were priority-controlled antibiotics in urban waters. Tetracyclines (TCs) posed medium to high risks to soil organisms in the soil of urban agglomerations. Health risk evaluation based on dietary intake showed that children had the highest dietary intake of antibiotics in urban agglomerations. The health risk of antibiotics was higher in children than in other age groups. Our results also demonstrated that dietary structure might impact health risks associated with target antibiotics in urban agglomerations to some extent.

Low uptake of pharmaceuticals in edible mushrooms grown in polluted biogas digestate

The uptake dynamics of two sulfonamide antibiotics, two fluoroquinolone antibiotics, and the anticonvulsant carbamazepine during the cultivation of two species of edible mushrooms (Agaricus subrufescens and A. bisporus) was investigated. None of the antibiotics were accumulated by the mushrooms, while carbamazepine and its transformation product carbamazepine-10,11-epoxide were taken up by A. bisporus fruiting body but only in small amounts (up to 0.76 and 1.85 μg kg-1 dry weight, respectively). The sulfonamides were quickly removed from the mushroom growth substrate, while the recalcitrant fluoroquinolones and carbamazepine were only partially removed. Dissipation half-lives were generally lower for A. subrufescens than A. bisporus, but A. subrufescens was also grown at a slightly higher culture temperature. A. subrufescens also showed a lower uptake of contaminants. Comparison of maximum dietary intake with other common exposure sources showed that these mushrooms can safely be eaten although produced on a polluted substrate, with respect to the investigated compounds.

Synthesis and characterization of polysiphonia/cerium oxide/nickel oxide nanocomposites for the removal of toxins from contaminated water and antibacterial potential

Due to massive industrial development, organic and inorganic wastes are very common in most industrial effluents from the pharmaceutical industry. Even in low concentrations, they are very dangerous and harmful to humans and other living organisms. Antibiotics are frequently detected in surface waters, in soil, in wastewater from sewage treatment plants, and even in drinking water. The major environmental threat they pose has prompted to search for effective and environmentally friendly means of eliminating these toxins. The biogenic synthesis of nanomaterials using natural herbal extracts has attracted considerable attention due to their low-cost, environmentally friendly and non-toxic nature, and as a reversal of various physical and chemical processes. The ceria nanoparticles (CeO2 NPs), nickel oxide nanoparticles (NiO NPs), and CeO2/NiO nanocomposites (CeO2/NiO NCS) were successfully prepared by simple biosynthetic routes using Polysiphonia urceolata algae extract as green surfactants and tested for toxic ofloxacin removal efficiency. The formed nanostructures were identified and characterized by various microscopic (FESEM-EDX, TEM, XRD, BET, and XPS) and spectroscopic (UV-Vis, FTIR, and TGA) methods. The adsorption/desorption of ofloxacin (OFX) on the surface of the nanomaterials was investigated under optimized conditions (initial dose 20 mg/L, agitation speed 250 rpm, pH 12, adsorbent dose 0.5 mg/L, and contact time 120 min). The removal efficiencies were 78%, 86%, and 94% for CeO2 NPs, NiO NPs and CeO2/NiO NCS, respectively, where OFX removal was found to be spontaneous, followed by Freundlich isotherm and pseudo-second order kinetic reaction model. The OFX adsorption mechanism on the nanomaterials involved the surface complexation via specific electrostatic attraction and H-bonding. The biogenic nanomaterials were also tested for their antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus epidermidis and Staphylococcus aureus. The CeO2/NiO NCS exhibited the highest antibacterial activity with zone of inhibition (31.12 ± 0.59 mm) against S. epidermidis, followed by CeO2NPs and NiONPs with zones of inhibition (25.53 ± 1.2 mm) and (21.42 ± 0.6 mm) against P. aeruginosa and S. epidermidis, respectively. This study demonstrated the efficiency of the synthesized nanomaterials in removing toxins such as OFX from contaminated water and can serve as potential antibacterial and antioxidant agents. Notably, the heterogeneous nanomaterials demonstrated remarkable stability across a broad pH range, promising reusability and indicated tremendous potential of waste biomass reduction and OFX effluent treatment.

Occurrence and partitioning of p-phenylenediamine antioxidants and their quinone derivatives in water and sediment

p-Phenylenediamine antioxidants (PPDs) and PPDs-derived quinones (PPDQs) may pose a threat to the river ecosystem. However, the knowledge on the occurrence and environmental behaviors of PPDs and PPDQs in the natural river environment remains unknown. In this study, we collected paired water (n = 30) and sediment samples (n = 30) from Jiaojiang River, China and analyzed them for nine PPDs and seven PPDQs. Our results showed that target PPDs and PPDQs are frequently detected in water samples, with the dominance of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD; mean 12 ng/L, range 4.0-72 ng/L) and 6PPD-derived quinone (6PPDQ; 7.0 ng/L, Collapse

Key Words

• PPDQs
• PPDs
• Partitioning
• Sediment
• Water

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MESH Headings Collapse

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Affiliation(s)

Jianqiang Zhu Department of Environmental Engineering, Taizhou University, Taizhou, Zhejiang 318000, PR China
Ruyue Guo Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou, Zhejiang 310032, PR China
Fangfang Ren Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou, Zhejiang 310032, PR China
Shengtao Jiang Department of Environmental Engineering, Taizhou University, Taizhou, Zhejiang 318000, PR China
Hangbiao Jin Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou, Zhejiang 310032, PR China; Innovation Research Center of Advanced Environmental Technology, Eco-Industrial Innovation Institute ZJUT, Quzhou, Zhejiang 324400, PR China.

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The occurrence of heavy metals and antimicrobials in sewage sludge and their predicted risk to soil - Is there anything to fear?

The study assessed the occurrence of legally-monitored heavy metals and unmonitored antimicrobials in sludge from small, medium, large and very large municipal wastewater treatment plants (WWTPs), and the predicted environmental risk and risk of resistance selection associated with sludge administration to soil. The temporal variations of the studied compounds in sludge and associated risks to soil were determined by sampling over a year. Although the highest concentrations of heavy metals were noted in sludge from the largest WWTP, i.e. from 1.50 mg/kg (mean 1.61 mg/kg) for Cd to 2188 mg/kg (mean 1332 mg/kg) for Zn, the obtained values only reached a few percent of the legal limits. The same WWTP also demonstrated lower concentrations of antimicrobials compared to the smaller ones. The highest concentrations of antimicrobials, ranging from 24.04 μg/kg for trimethoprim to 900.24 μg/kg for tetracycline, were found in the small and medium WWTPs. However, due to lack of regulations at the national and EU levels, the results cannot be compared with legal limits. Principal Component Analysis (PCA), cluster and heatmap analysis separated samples according to WWTP size. Small WWTP demonstrated correlation with antimicrobials (tetracycline, trimethoprim, clindamycin, ciprofloxacin and ofloxacin), while the large and very large WWTP revealed correlations with heavy metals (Cu and Cr). The obtained environmental risk quotients confirmed that the heavy metals did not present a threat, measured either as individual risk quotients (RQenv), cumulative risk (RQcumulative) or risk of mixture of heavy metals (RQmix-metals). In the case of antimicrobials, only tetracycline demonstrated moderate RQenv, RQcumulative and RQmix-antimicrobials in the small WWTP sludge, with values of 0.1 to 1. Our findings highlight the importance of monitoring sewage sludge before soil application, especially from small WWTPs, to reduce the potential environmental impact of antimicrobials. They also confirm our previous data regarding the environmental risk associated with various toxic compounds, including emerging contaminants, in the sludge from small WWTPs.

Competitive adsorption and bioaccumulation of sulfamethoxazole and roxithromycin by sediment and zebrafish (Danio rerio) during individual and combined exposure in water

Antibiotics are extensively used for health protection and food production, causing antibiotic pollution in the aquatic environment. This study aims to determine the bioavailability and bioaccumulation of typical antibiotics sulfamethoxazole (SMX) and roxithromycin (RTM) in zebrafish under environmentally realistic conditions. Four different microcosms, i.e. water, water-sediment, water-zebrafish, and water-sediment-zebrafish were constructed, with three replicates in parallel. The concentrations of SMX and RTM in water, sediment and zebrafish were extracted and analyzed by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) to assess their kinetic behavior and bioavailability. In the water-sediment system, the dissolved concentration of both SMX and RTM decreased with time following the first-order kinetic while their adsorption by sediment increased with time. In the water-zebrafish system, SMX and RTM bioaccumulation was increasing with time following the pseudo second-order kinetics. RTM bioaccumulation in zebrafish (up to 16.4 ng/g) was an order of magnitude higher than SMX (up to 5.2 ng/g), likely due to RTM being more hydrophobic than SMX. In addition, the bioaccumulation factor (BAF) value of SMX in zebrafish was greater than its sediment partition coefficient, while the opposite trend was observed for RTM, demonstrating the importance of antibiotics properties in affecting their bioavailability. Furthermore, increasing dissolved organic carbon concentration in water reduced SMX bioaccumulation, but increased RTM bioaccumulation at the same time. The findings are important in future studies of environmental fate and bioavailability of toxic chemicals with different pollution sources and physicochemical properties.

Mapping the scarcity of data on antibiotics in natural and engineered water environments across India

Antimicrobial resistance is a growing public health concern, increasingly recognized as a silent pandemic across the globe. Therefore, it is important to monitor all factors that could contribute to the emergence, maintenance and spread of antimicrobial resistance. Environmental antibiotic pollution is thought to be one of the contributing factors. India is one of the world's largest consumers and producers of antibiotics. Hence, antibiotics have been detected in different environments across India, sometimes at very high concentrations due to their extensive use in humans and agriculture or due to manufacturing. We summarize the current state of knowledge on the occurrence and transport pathways of antibiotics in Indian water environments, including sewage or wastewater and treatment plants, surface waters such as rivers, lakes, and reservoirs as well as groundwater and drinking water. The factors influencing the distribution of antibiotics in the water environment, such as rainfall, population density and variations in sewage treatment are discussed, followed by existing regulations and policies aimed at the mitigation of environmental antimicrobial resistance in India, which will have global benefits. Then, we recommend directions for future research, development of standardized methods for monitoring antibiotics in water, ecological risk assessment, and exploration of strategies to prevent antibiotics from entering the environment. Finally, we provide an evaluation of how scarce the data is, and how a systematic understanding of the occurrence and concentrations of antibiotics in the water environment in India could be achieved. Overall, we highlight the urgent need for sustainable solutions to monitor and mitigate the impact of antibiotics on environmental, animal, and public health.

Toxic effects of lead (Pb), cadmium (Cd) and tetracycline (TC) on the growth and development of Triticum aestivum: A meta-analysis

The environmental issue of lead (Pb), cadmium (Cd), and tetracycline (TC) contamination in cereal crops has become a growing concern worldwide. An in-depth understanding of this issue would be of importance to promote effective management strategies for heavy metals and antibiotics worldwide. The present study was conducted to assess the toxic effects of heavy metals (Cd, Pb) and antibiotics (TC) on Triticum aestivum (T. aestivum, common wheat) based on studies conducted in the past 22 years. Data pertaining to the growth and development of T. aestivum were extracted and analyzed from 89 publications spanning from 2000 to 2022. Our results showed that Pb, Cd and TC significantly reduced growth and development by 11 %, 9 %, and 5 %, respectively. Additionally, significant accumulation of Cd (42 %) and Pb (17 %) was observed in T. aestivum samples, although there was little change in TC accumulation, which showed limited absorption, accumulation, and translocation of TC in wheat plants. Pb had the greatest impact on the yield of T. aestivum, followed by Cd, while TC had no apparent effect. Furthermore, exposure to Cd, Pb and TC reduced the photosynthetic rate due to chlorophyll reduction, with Cd having the most pronounced effect (58 %), followed by Pb (37 %) and TC (8 %). Cd exposure also significantly enhanced gaseous exchange (37 %) compared to TC and Pb, which reduced gaseous exchange by 4 % and 10 %, respectively. However, the treatments with TC (>50-100 mgL-1), Pb (>1000-2000 mg L-1) and Cd (>500-1000 mg L-1) increased the defense system of T. aestivum samples by 38 %, 15 %, and 11 %, respectively. The obtained findings have significant implications for risk assessment, pollution prevention, and remediation strategies to address soil contamination from Pb, Cd and TC in farmland.

Prioritization of organic contaminants in a reclaimed water irrigation system using wide-scope LC-HRMS screening

A prioritization procedure was developed and implemented at the local level to identify the most relevant organic contaminants of emerging concern (CECs) in an agricultural area irrigated with reclaimed water. A wide-scope screening methodology based on UPLC-HRMS analysis was applied to holistically characterize the CEC footprint in water and its spatial and temporal variations. One hundred and fifty-eight CECs, including pharmaceuticals, industrial chemicals, and pesticides, among others, were identified with a confidence level of 2 in the water samples investigated. After water treatment in the reclamation plant and transport within the irrigation channel network, more than a hundred compounds were still detected at the location where water is abstracted for crop irrigation. Compound ecotoxicity and occurrence (semi-quantified concentrations or peak intensity) were the parameters used to prioritize CECs in the water used for irrigation. Results pointed at venlafaxine, O-desmethyl-venlafaxine, galaxolidone, theophylline/paraxanthine, oxybenzone, and N-phenyl-1-naphtylamine, among others, as CECs of concern in the investigated area. This study provides a simple and cost-effective approach to detecting site-specific priority pollutants that could otherwise be overlooked by national or European regulations. The prioritization tool provided contributes to rationally designing monitoring and attenuation programs and efficiently managing water resources, by ensuring the safety of reclaimed water applications.

Antibiotics and their associations with antibiotic resistance genes and microbial communities in estuarine and coastal sediment of Quanzhou Bay, Southeast China

The antibiotic concentrations spanned from 11.2 to 173.8 ng/g, with quinolones and tetracyclines being observed to be prevalent. The amount of microbial biomass as determined by Phospholipid fatty acid (PLFA) ranged from 2.92 to 10.99 mg kg-1, with G- bacteria dominating. A total of 254 distinct ARGs and 10 MEGs were identified, with multidrug ARGs having the highest relative abundance (1.18 × 10-2 to 3.00 × 10-1 copies/16S rRNA gene copies), while vancomycin and sulfonamide resistance genes were the least abundant. Results from canonical-correlation analyses combined with redundancy analysis indicated that macrolides were significantly related to the shifts of microbial community structure in sediments, particularly in G+ bacteria that were more sensitive to antibiotic residues. It was observed that sulfonamide ARGs had a greater correlation with residual antibiotics than other ARGs. This study provided a field evidence that multiple residual antibiotics from coastal sites could cause fundamental shifts in microbial community and their associated ARGs.

Advancements in electrochemical technologies for the removal of fluoroquinolone antibiotics in wastewater: A review

In recent times, the need to make water safer and cleaner through the elimination of recalcitrant pharmaceutical residues has been the aim of many studies. Fluoroquinolone antibiotics such as ciprofloxacin, norfloxacin, enrofloxacin, and levofloxacin are among the commonly detected pharmaceuticals in wastewater. Since the presence of these pharmaceuticals in water bodies poses serious risks to living organisms, it is vital to adopt effective wastewater treatment techniques for their complete removal. Electrochemical technologies such as photoelectrocatalysis, electro-Fenton, electrocoagulation, and electrochemical oxidation have been established as techniques capable of the complete removal of organics including pharmaceuticals from wastewater. Hence, this review presents discussions on the recent progress (literature within 2018-2022) in the applications of common electrochemical processes for the degradation of fluoroquinolone antibiotics from wastewater. The fundamentals of these processes are highlighted while the results obtained using the processes are critically discussed. Furthermore, the inherent advantages and limitations of these processes in the mineralization of fluoroquinolone antibiotics are clearly emphasized. Additionally, appropriate recommendations are made toward improving electrochemical technologies for the complete removal of these pharmaceuticals with minimal energy consumption. Therefore, this review will serve as a bedrock for future researchers concerned with wastewater treatments to make informed decisions in the selection of suitable electrochemical techniques for the removal of pharmaceuticals from wastewater.

Riverine antibiotic occurrence and potential ecological risks in a low-urbanized and rural basin of the middle Yangtze River: Socioeconomic, land use, and seasonal effects

This study firstly investigated the effects of season, land use, and socioeconomic on the spatiotemporal changes of riverine antibiotic concentrations in a low urbanized and rural watershed. In the dry and wet seasons, water samples were collected and analyzed for 15 antibiotics. The results indicated that 14 antibiotics, excluding leucomycin, were detected. Monsoon led to significantly lower total antibiotic concentrations in the wet season (22.0ngL^-1) than in the dry season (51.2ngL^-1). Total antibiotic concentrations were dominated by amoxicillin (below limit of detection (<LOD)-34.7ngL^-1)), erythromycin-H₂O (<LOD-14.7ngL^-1), roxithromycin (<LOD-27.9ngL^-1), and trimethoprim (<LOD-6.34ngL^-1). The total antibiotic concentrations were usually higher in the downstream areas of urban land than in the river reaches of forest land and agricultural land. At county or city scales, total antibiotic concentrations in the dry season were significantly correlated with the rural population, public budget, husbandry product and output, effluent volume, fishery product and output, and hospital number, which generally depend on land use in the basin. Amoxicillin poses a high ecological risk to aquatic algae, whereas erythromycin-H₂O, ofloxacin, and norfloxacin pose medium ecological risks. However, trimethoprim poses a medium ecological risk to mollusks. These results provide improved insights into the characteristics of antibiotic occurrence and ecological risks in the waters of low-urbanized and rural areas in China and can be extrapolated worldwide.

A mega study of antibiotics contamination in Eastern aquatic ecosystems of China: occurrence, interphase transfer processes, ecotoxicological risks, and source modeling

Understanding the occurrence, sources, transfer mechanisms, fugacity, and ecotoxicological risks of antibiotics play a pivotal role in improving the sustainability and ecological health of freshwater ecosystems. Therefore, in order to determine the levels of antibiotics, water and sediment samples were collected from multiple Eastern freshwater ecosystems (EFEs) of China, including Luoma Lake (LML), Yuqiao Reservoir (YQR), Songhua Lake (SHL), Dahuofang Reservoir (DHR), and Xiaoxingkai Lake (XKL), and were analyzed using Ultra Performance Liquid Chromatography/Tandem Mass Spectrometry (UPLC-MS/MS). EFEs regions are particularly interesting due to higher urban density, industrialization, and diverse land use in China. The findings revealed that a collective total of 15 antibiotics categorized into four families, which included sulfonamides (SAs), fluoroquinolones (FQs), tetracyclines (TCs), and macrolides (MLs), exhibited high detection frequencies, indicating widespread antibiotic contamination. The pollution levels in the water phase were in the order of LML > DHR > XKL > SHL > YQR. The sum concentration of individual antibiotics for each water body ranged from not detected (ND) to 57.48 ng/L (LML), ND to 12.25 ng/L (YQR), ND to 57.7 ng/L (SHL), ND to 40.50 ng/L (DHR), and ND to 26.30 ng/L (XKL) in the water phase. Similarly, in the sediment phase, the sum concentration of individual antibiotics ranged from ND to 15.35 ng/g, ND to 198.75 ng/g, ND to 1233.34 ng/g, ND to 388.44 ng/g, and ND to 862.19 ng/g, for LML, YQR, SHL, DHR, and XKL, respectively. Interphase fugacity (ff_sw) and partition coefficient (K_d) indicated dominant resuspension of antibiotics from sediment to water, causing secondary pollution in EFEs. Two groups of antibiotics, namely MLs (erythromycin, azithromycin, and roxithromycin) and FQs (ofloxacin and enrofloxacin), showed a medium-high level of adsorption tendency on sediment. Source modeling (PMF5.0) identified wastewater treatment plants, sewage, hospitals, aquaculture, and agriculture as the major antibiotic pollution sources in EFEs, contributing between 6% and 80% to different aquatic bodies. Finally, the ecological risk posed by antibiotics ranged from medium to high in EFEs. This study offers valuable insights into the levels, transfer mechanisms, and risks associated with antibiotics in EFEs, enabling the formulation of large-scale policies for pollution control.

Partitioning and migration of antibiotic resistance genes at soil-water-air interface mediated by plasmids

The partitioning and migration of antibiotic resistance genes (ARGs) at the interfaces of soil, water, and air play a critical role in the environmental transmission of antibiotic resistance. This study investigated the partitioning and migration of resistant plasmids as representatives of extracellular-ARGs (eARGs) in artificially constructed soil-water-air systems. Additionally, it quantitatively studied the influence of soil pH, clay mineral content, organic matter content, and simulated rainfall on the migration of eARGs via orthogonal experiments. The findings revealed that the sorption equilibrium between eARGs and soil can be attained within 3 h, following the two-compartment first-order kinetic model. The average partition ratio of eARGs in soil, water, and air is 7:2:1, and soil pH and clay mineral content are identified as the main influencing factors. The proportion of eARGs migrating from soil to water and air is 8.05% and 0.52%, respectively. Correlation and significance analyses showed that soil pH has a significant impact on the soil-water and soil-air mobility of eARGs, while clay content affects the percentage of peaks during migration. Moreover, rainfall exerts a noticeable impact on the timing of peaks during migration. This study provided quantitative insights into the proportion of eARGs in soil, water, and air and elucidated the key factors influencing the partitioning and migration of eARGs from the perspectives of the sorption mechanism.

Transfer route and driving forces of antibiotic resistance genes from reclaimed water to groundwater

The infiltration of reclaimed water has created a significant environmental risk due to the spread of antibiotic resistance genes (ARGs) in riparian groundwater. Reclaimed water from wastewater treatment plants (WWTPs) had been identified as a source of both antibiotics and ARGs in groundwater, based on their spatial and temporal distribution. The assembly process of microbial communities in the groundwater of the infiltration zone was more influenced by deterministic processes. Co-occurrence network analysis revealed that Thermotoga, Desulfotomaculum, Methanobacterium, and other such genera were dominant shared genera. These were considered core genera and hosts of ARGs for transport from reclaimed water to groundwater. The most abundant ARG in these shared genera was MacB, enriched in groundwater point G3 and potentially transferred from reclaimed water to groundwater by Acidovorax, Hydrogenophaga, Methylotenera, Dechloromonas, and Nitrospira. During the infiltration process, environmental factors and the tradeoff between energy metabolism and antibiotic defense strategy may have affected ARG transfer. Understanding the transfer route and driving forces of ARGs from reclaimed water to groundwater provided a new perspective for evaluating the spread risk of ARGs in reclaimed water infiltration.