First insight into the occurrence, spatial distribution, sources, and risks assessment of antibiotics in groundwater from major urban-rural settings of Pakistan

Three-Dimensional Electrosorption for Pharmaceutical Wastewater Management and Sustainable Biochar Regeneration

The adsorption capacity of a biochar (BC) obtained from pine wood residues was evaluated for its ability to remove two pharmaceuticals: fluoxetine (FLX) and sulfamethizole (SMZ). The material showed promising results in FLX removal, but a limited capacity in the case of SMZ. In order to improve these results, BC surface modifications were made by doping with nitrogen, as well as using acid, basic and electrochemical treatments. A three-dimensional electrosorption treatment proved to be the most effective, increasing the adsorption rate from 0.45 to 13.46 mg/g after evaluating different operating conditions, such as the electrodes used or the BC dosage. Consecutive cycles of BC use were performed through desorption and electro-regeneration techniques to test its capacity for reuse, and it was observed that application in the 25 mA electric field increased the useful life of the material. Finally, the effect of ionic strength was studied, highlighting that the presence of ions did not significantly affect the efficiency of SMZ removal, although a slight increase was observed at a high ion concentration, probably due to a salinization effect.

Co-occurrence of microplastics, PFASs, antibiotics, and antibiotic resistance genes in groundwater and their composite impacts on indigenous microbial communities: A field study

There is a major gap in the occurrence of mixed emerging contaminants, which hinders our efforts in exploring their behaviors and transport in environmental media, as well as their toxicity to human and ecosystem. This study assessed the occurrence and their correlations of mixed contamination by microplastics (MPs), per- and polyfluoroalkyl substances (PFASs), antibiotics, and antibiotic resistance genes (ARGs) in groundwater collected from a pharmaceutical and chemical industrial park. MPs, PFASs, antibiotics and ARGs were detected at all monitoring wells. The total concentration range of MPs and 20 PFASs were 693-1032 pieces/L and 577.47-2982.45 ng/L, respectively, with perfluorooctanoic acid (PFOA) being the most prevalent compound among PFASs in groundwater. The abundance of detected target antibiotics and ARGs ranged from 1.97 to 30.65 ng/L and from 2.65 × 102 to 7.53 × 105 copies/mL, respectively. MPs and PFASs have a significant positive correlation, yet interestingly, no correlation was found between antibiotics and ARGs. In addition, the relatively high abundance of integron intI1 detected in the study area illustrated the potential horizontal transfer risk of ARGs in the subsurface. Furthermore, the effects of these mixed emerging contaminants on the indigenous microbial communities were elucidated. The coexistence of MPs, PFASs, antibiotics, and ARGs led to the enrichment of species that were tolerant to pollutants. Specifically, MPs, PFASs and ARGs were found to be positively correlated with Acinetobacter, unclassified_f__Comamonadaceae, Pseudomonas, Simplicispira and Proteiniphilum, while antibiotics were positively associated with Paenisporosarcina and Arthrobacter. Moreover, geochemical parameters such as oxidation-reduction potential and nitrate also played a key role in shaping the microbial community structure. The co-occurrence of mixed emerging contaminants highlighted in this study underscores the urgent need for comprehensive environmental monitoring, systematic toxicity assessments, and stricter regulatory frameworks. In addition, it offers insights in the development of effective bioremediation strategies to mitigate their impacts on both ecosystems and public health.

Regional distribution differences of antibiotics in tropical marine aquaculture area: Insights into antibiotic management and risk assessment

In recent years, global demand for marine aquaculture products has led to a significant rise in antibiotic use, particularly in tropical coastal aquaculture areas However, research on antibiotic residues in these environments remains limited, hindering a comprehensive understanding of their environmental presence and associated risks. This study investigates the regional distribution, ecological risks, and sources of 44 antibiotics in seawater across four coastal aquaculture areas in Hainan island (Wenchang, Sanya, Danzhou, and Wanning). Among the 44 antibiotics tested across 42 sampling sites, all were detected with a 100 % detection rate. Antibiotics such as Trimethoprim (TMP), Sulfanitran (APNPS), Sulfaquinoxaline (SQ), Sulfadimethoxine (SDT), Chloramphenicol (CHP), and Florfenicol (FLO) were consistently detected across all sampling sites. Total concentrations of detected antibiotics ranged from 0 to 818.79 ng.L-1, with sulfonamide antibiotics ranging from 0 to 629.49 ng.L-1, chloramphenicol antibiotics from 0 to 87.39 ng.L-1, tetracyclines from 0 to 221.39 ng.L-1, and fluoquinolones from 0 to 272.08 ng.L-1. The highest levels of antibiotic pollution were observed at the W5 sampling site in Wenchang, attributed to aquaculture wastewater discharge, while no antibiotics were found at D12 in Danzhou. In these regions, source analysis identified aquaculture and domestic sewage as the primary contributors to antibiotic pollution in these regions. Correlation analysis with environmental factors revealed significant influences of factors such as SAL, kPa, TN, SPC, and pH on sulfonamide and chloramphenicol antibiotics. Health risk assessment indicated moderate to high risks to aquatic organisms from antibiotics like NOR, CIP, ENR, OFL, TMP, and SMX in the study areas, underscoring the need for preventive measures, stricter regulation of antibiotic use, and enhanced ecological risk monitoring in aquaculture regions. This study provides critical insights into antibiotic contamination in Hainan's coastal aquaculture areas, highlighting the urgent need for further research into the occurrence and ecological impacts of these emerging pollutants in marine environments.

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.

Does exposure timing of macrolide antibiotics affect the development of river periphyton? Insights into the structure and function

Discharged sewage is the dominant source of urban river pollution. Macrolide antibiotics have emerged as prominent contaminants, which are frequently detected in sewage and rivers and pose a threat to aquatic microbial community. As a typical primary producer, periphyton is crucial for maintaining the biodiversity and functions of aquatic ecosystem. However, effects of antibiotic exposure time as well as the recovery process of periphyton remain undetermined. In the present study, five exposure scenarios of two typical macrolides, erythromycin (ERY) and roxithromycin (ROX) were investigated at 50 µg/L, dose to evaluate their potential detrimental effects on the structure and function of periphyton and the subsequent recovery process in 14 days. Results revealed that the composition of periphytic community returned to normal over the recovery period, except for a few sensitive species. The antibiotics-caused significant photodamage to photosystem II, leading to continuous inhibition of the photosynthetic capacity of periphyton. Furthermore, no significant difference in carbon metabolism capacity was observed after direct antibiotic exposure, while the amine carbon utilization capacity of periphyton remarkably increased during the recovery process. These results indicated that periphyton community was capable of coping with the periodic exposure of antibiotic pollutants and recovering on its own. However, the ecological functions of periphyton can be permanently disturbed due to macrolide exposure. Overall, this study sheds light on the influence of macrolide exposure on the development, structure and function of the periphytic microbial community in rivers.

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.

Unveiling combined ecotoxicity: Interactions and impacts of engineered nanoparticles and PPCPs

Emerging contaminants such as engineered nanoparticles (ENPs), pharmaceuticals and personal care products (PPCPs) are of great concern because of their wide distribution and incomplete removal in conventional wastewater and soil treatment processes. The production and usage of ENPs and PPCPs inevitably result in their coexistence in different environmental media, thus posing various risks to organisms in aquatic and terrestrial ecosystems. However, the existing literature on the physicochemical interactions between ENPs and PPCPs and their effects on organisms is rather limited. Therefore, this paper summarized the ecotoxicity of combined ENPs and PPCPs by discussing: (1) the interactions between ENPs and PPCPs, including processes such as aggregation, adsorption, transformation, and desorption, considering the influence of environmental factors like pH, ionic strength, dissolved organic matter, and temperature; (2) the effects of these interactions on bioaccumulation, bioavailability and biotoxicity in organisms at different trophic levels; (3) the impacted of ENPs and PPCPs on cellular-level biological process. This review elucidated the potential ecological hazards associated with the interaction of ENPs and PPCPs, and serves as a foundation for future investigations into the ecotoxicity and mode of action of ENPs, PPCPs, and their co-occurring metabolites.

Protecting the Last Line of Defense: Analytical Approaches for Sample Preparation and Determination of the Reserve Group of Antibiotics in the Environment

Drug resistance in microorganisms is a serious threat to life and health due to the limited number of antibiotics that show efficacy in treating infections and the difficulty in discovering new compounds with antibacterial activity. To address this issue, the World Health Organization created the AWaRe classification, a tool to support global and national antimicrobial stewardship programs. The AWaRe list categorizes antimicrobials into three groups - Access, Watch, and Reserve - according to their intended use. The Reserve group comprises "last resort" medicines used solely for treating infections caused by bacterial strains that are resistant to other treatments. It is therefore necessary to protect them, not only by using them as prudently as possible in humans and animals, but also by monitoring their subsequent fate. Unmetabolized antibiotics enter the environment through hospital and municipal wastewater or from manure, subsequently contaminating bodies of water and soils, thus contributing to the emergence and spread of antibiotic resistance. This article presents a review of determination methods for the Reserve group of antimicrobials in water, wastewater, and manure. Procedures for extracting and determining these substances in environmental samples are described, showing the limited research available, which is typically on a local level.

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.

A comprehensive review on the fate and impact of antibiotic residues in the environment and public health: A special focus on the developing countries

The widespread application of antibiotics in human and veterinary medicine has led to the pervasive presence of antibiotic residues in the environment, posing a potential hazard to public health. This comprehensive review aims to scrutinize the fate and impact of antibiotic residues, with a particular focus on the context of developing nations. The investigation delves into the diverse pathways facilitating the entry of antibiotics into the environment and meticulously examines their effects on human health. The review delineates the current state of antibiotic residues, evaluates their exposure in developing nations, and elucidates existing removal methodologies. Additionally, it probes into the factors contributing to the endurance and ecotoxicity of antibiotic residues, correlating these aspects with usage rates and associated mortalities in these nations. The study also investigates removal techniques for antibiotic residues, assessing their efficiency in environmental compartments. The concurrent emergence of antibiotic-resistant bacteria, engendered by antibiotic residues, and their adverse ecological threats underscore the necessity for enhanced regulations, vigilant surveillance programs, and the adoption of sustainable alternatives. The review underlines the pivotal role of public education and awareness campaigns in promoting responsible antibiotic use. The synthesis concludes with strategic recommendations, strengthening the imperative for further research encompassing comprehensive monitoring, ecotoxicological effects, alternative strategies, socio-economic considerations, and international collaborations, all aimed at mitigating the detrimental effects of antibiotic residues on human health and the environment. PRACTITIONER POINTS: Antibiotic residues are widely distributed in different environmental compartments. Developing countries use more antibiotics than developed countries. Human and veterinary wastes are one of the most responsible sources of antibiotic pollution. Antibiotics interact with biological systems and trigger pharmacological reactions at low doses. Antibiotics can be removed using modern biological, chemical, and physical-chemical techniques.

Antibiotic occurrence, environmental risks, and their removal from aquatic environments using microalgae: Advances and future perspectives

Antibiotic pollution has caused a continuous increase in the development of antibiotic-resistant bacteria and antibiotic-resistant genes (ARGs) in aquatic environments worldwide. Algae-based bioremediation technology is a promising eco-friendly means to remove antibiotics and highly resistant ARGs, and the generated biomass can be utilized to produce value-added products of industrial significance. This review discussed the prevalence of antibiotics and ARGs in aquatic environments and their environmental risks to non-target organisms. The potential of various microalgal species for antibiotic and ARG removal, their mechanisms, strategies for enhanced removal, and future directions were reviewed. Antibiotics can be degraded into non-toxic compounds in microalgal cells through the action of extracellular polymeric substances, glutathione-S-transferase, and cytochrome P450; however, antibiotic stress can alter microalgal gene expression and growth. This review also deciphered the effect of antibiotic stress on microalgal physiology, biomass production, and biochemical composition that can impact their commercial applications.

Toxicity of tigecycline on the freshwater microalga Scenedesmus obliquus: Photosynthetic and transcriptional responses

Tigecycline (TGC) is a new tetracycline antibiotic medication against multidrug-resistant bacteria. However, the toxicity of TGC to microalgae remains largely unknown. In this study, the toxicity of TGC on Scenedesmus obliquus was examined, focusing on changes in algal growth, photosynthetic activity, and transcriptome. According to an acute toxicity test, the IC10 and IC50 values were 0.72 mg/L and 4.15 mg/L, respectively. Analyses of photosynthetic efficiency and related parameters, such as light absorption, energy capture, and electron transport, identified a 35% perturbation in the IC50 group, while the IC10 group remained largely unaffected. Transcriptomic analysis showed that in the IC10 and IC50 treatment groups, there were 874 differentially expressed genes (DEGs) (220 upregulated and 654 downregulated) and 4289 DEGs (2660 upregulated and 1629 downregulated), respectively. Gene Ontology enrichment analysis showed that TGC treatment markedly affected photosynthesis, electron transport, and chloroplast functions. In the IC50 group, a clear upregulation of genes related to photosynthesis and chloroplast functions was observed, which could be an adaptive stress response. In the IC10 group, significant downregulation of DEGs involved in ribosomal pathways and peptide biosynthesis processes was observed. Kyoto Encyclopedia of Gene and Genomes enrichment analysis showed that treatment with TGC also disrupted energy production, protein synthesis, and metabolic processes in S. obliquus. Significant downregulation of key proteins related to Photosystem II was observed under the IC10 TGC treatment. Conversely, IC50 TGC treatment resulted in substantial upregulation across a broad array of photosystem-related proteins from both Photosystems II and I. IC10 and IC50 TGC treatments differentially influenced proteins involved in the photosynthetic electron transport process. This study emphasizes the potential risks of TGC pollution to microalgae, which contributes to a better understanding of the effects of antibiotic contamination in aquatic ecosystems.

Veterinary pharmaceutical as emerging contaminants in wastewater and surface water: An overview

Veterinary pharmaceuticals have become of interest due to their indiscriminate use. Thus, this paper compiles studies on detection in surface and wastewater, and the treatment applied for their removal. Additionally, a case study was performed to evaluate its commercialization, as the ecological risk assessment for the most relevant compounds. 241 compounds were detected. The highest concentrations were found for antibiotics such as oxytetracycline, amoxicillin, and monensin, with values up to 3732.4 µg/L. Biological treatments have been mainly reported, obtaining removal greater than 80% for sulfadiazine, sulfamethazine, sulfamethoxazole, enrofloxacin, and oxytetracycline. Considering the case study, enrofloxacin and oxytetracycline were widely commercialized. Finally, there was a low risk for the species exposed to enrofloxacin, in contrast, the species exposed to oxytetracycline presented a high risk of long-term mortality. Concluding that veterinary compounds have emerged as a significant concern regarding water source contamination, owing to their potential adverse effects on aquatic biota and even human. This is particularly relevant because many water bodies that receive wastewater are utilized for drinking water purposes. Consequently, the development of comprehensive, full-scale systems for efficient antibiotic removal before their introduction into water sources becomes imperative. Equally important is the need to reconsider their extensive use altogether.

Occurrence of antibiotics in wastewater: Potential ecological risk and removal through anaerobic-aerobic systems

Antibiotics are intensively used to improve public health, prevent diseases and enhance productivity in animal farms. Contrarily, when released, the antibiotics laden wastewater produced from pharmaceutical industries and their application sources poses a potential ecological risk to the environment. This study provides a discussion on the occurrence of various antibiotics in wastewater and their potential ecological risk in the environment. Further, a critical review of anaerobic-aerobic processes based on three major systems (such as constructed wetland, high-rate bioreactor, and integrated treatment technologies) applied for antibiotics removal from wastewater is performed. The review also explores microbial dynamics responsible for antibiotic biodegradation in anaerobic-aerobic systems and its economic feasibility at wider-scale applications. The operational problems and prospective modifications are discussed to define key future research directions. The appropriate selection of treatment processes, sources control, understanding of antibiotic fate, and adopting precise monitoring strategies could eliminate the potential ecological risks of antibiotics. Integrated bio-electrochemical systems exhibit antibiotics removal ≥95% by dominant Geobacter sp. at short HRT ∼4-10 h. Major process factors like organic loading rate, hydraulic loading rate (HRT), and solid retention time significantly affect the system performance. This review will be beneficial to the researchers by providing in-depth understanding of antibiotic pollution and its abatement via anaerobic-aerobic processes to develop sustainable wastewater treatment technology in the future.

The dynamics and transmission of antibiotic resistance associated with plant microbiomes

Antibiotic resistance genes (ARGs) have been widely found and studied in soil and water environments. However, the propagation of ARGs in plant microbiomes has attracted insufficient attention. Plant microbiomes, especially the rhizosphere microorganisms, are closely connected with water, soil, and air, which allows ARGs to spread widely in ecosystems and pose a threat to human health after entering the human body with bacteria. Therefore, it is necessary to deeply understand and explore the dynamics and the transmission of ARGs in rhizosphere microorganisms and endophytes of plants. In this review, the transmission and influencing factors of ARGs in the microorganisms associated with plants, especially the influence of root exudates on plant microbiomes, are analyzed. Notably, the role of intrinsic genes of plants in determining root exudates and their potential effects on ARGs are proposed and analyzed. The important role of phyllosphere microorganisms and endophytes in the transmission of ARGs and co-resistance of antibiotics and other substances are also emphasized. The proliferation and transmission of ARGs associated with plant microbiomes addressed in this review is conducive to revealing the fate of ARGs in plant microorganisms and alleviating ARG pollution.

Bacillus licheniformis reverses the environmental ceftriaxone sodium-induced gut microbial dysbiosis and intestinal inflammation in mice

Antibiotics used as a common clinical treatment have saved many lives. Widespread use of antibiotic therapy has been known to disrupt the balance of pathogenic bacteria, host-associated microorganisms and environment. However, our understanding of Bacillus licheniformis for health benefits and ability to restore the ceftriaxone sodium-induced gut microbial dysbiosis is severely limited. We used Caco-2 cell, H&E (hematoxylin-eosin staining), RT-PCR and 16S rRNA sequencing techniques to investigate the influence of Bacillus licheniformis on gut microbial dysbiosis and inflammation following ceftriaxone sodium treatment. The results showed that treatment of ceftriaxone sodium in 7 days suppressed the expression of Nf-κB pathway mRNA levels, which caused cytoplasmic vacuolization in intestinal tissues, afterward, the administration of Bacillus licheniformis could effectively restore intestinal morphology and inflammation levels. Moreover, the ceftriaxone sodium treatment entirely affected the intestinal microbial ecology, leading to a decrease in microbial abundance. Firmicutes, Proteobacteria, and Epsilonbacteraeota were the most predominant phyla in each of the four groups. Specifically, the MA group (ceftriaxone sodium treatment) resulted in a significant decrease in the relative abundance of 2 bacterial phyla and 20 bacterial genera compared to the administration of Bacillus licheniformis after ceftriaxone sodium treatment. The supplementation of Bacillus licheniformis could increase the growth of Firmicutes and Lactobacillus and encourage the construction of a more mature and stable microbiome. Furthermore, Bacillus licheniformis could restore the intestinal microbiome disorders and inflammation levels following ceftriaxone sodium treatment.

Removal of tetracycline from wastewater using g-C3N4 based photocatalysts: A review

Tetracycline is currently one of the most consumed antibiotics for human therapy, veterinary purpose, and agricultural activities. Tetracycline worldwide consumption is expected to rise by about more than 30% by 2030. The persistence of tetracycline has necessitated implementing and adopting strategies to protect aquatic systems and the environment from noxious pollutants. Here, graphitic carbon nitride-based photocatalytic technology is considered because of higher visible light photocatalytic activity, low cost, and non-toxicity. Thus, this review highlights the recent progress in the photocatalytic degradation of tetracycline using g-C₃N₄-based photocatalysts. Additionally, properties, worldwide consumption, occurrence, and environmental impacts of tetracycline are comprehensively addressed. Studies proved the occurrence of tetracycline in all water matrices across the world with a maximum concentration of 54 μg/L. Among different g-C₃N₄-based materials, heterojunctions exhibited the maximum photocatalytic degradation of 100% with the reusability of 5 cycles. The photocatalytic membranes are found to be feasible due to easiness in recovery and better reusability. Limitations of g-C₃N₄-based wastewater treatment technology and efficient solutions are also emphasized in detail.

Removal of Pharmaceuticals and Personal Care Products (PPCPs) by Free Radicals in Advanced Oxidation Processes

As emerging pollutants, pharmaceutical and personal care products (PPCPs) have received extensive attention due to their high detection frequency (with concentrations ranging from ng/L to μg/L) and potential risk to aqueous environments and human health. Advanced oxidation processes (AOPs) are effective techniques for the removal of PPCPs from water environments. In AOPs, different types of free radicals (HO·, SO₄·^-, O₂·^-, etc.) are generated to decompose PPCPs into non-toxic and small-molecule compounds, finally leading to the decomposition of PPCPs. This review systematically summarizes the features of various AOPs and the removal of PPCPs by different free radicals. The operation conditions and comprehensive performance of different types of free radicals are summarized, and the reaction mechanisms are further revealed. This review will provide a quick understanding of AOPs for later researchers.

An exhaustive investigation on antibiotics contamination from livestock farms within sensitive reservoir water area: Spatial density, source apportionment and risk assessment

Although the studies on antibiotic contamination are common at present, large-scale sampling studies drawing highly representative conclusions are still scarce. This study conducted a comprehensive investigation on a total of 1183 samples from 70 livestock farms within a sensitive area around reservoir waters. 45 types of antibiotics belonging to 5 different classes were monitored. This is the first analysis to comprehensively investigate the density distribution, source apportionment, ecological and health risk of antibiotics in an entire area of sensitive waters. The results showed that the layer manure samples had highest detection rate of antibiotics (0.0 %-96.1 %, average value = 30.7 %) followed by pig manure samples. Oxytetracycline had the highest concentration of 712.16 mg/kg in a pig manure sample. Different from using antibiotic concentration as a proxy for pollution level, the spatial density was calculated by averaging antibiotic concentration to area and converting different livestock to pig equivalent. The spatial density of pig equivalent can more realistically reflect the pollution caused by different breeds of livestocks. It was shown that the pig farms contributed higher to total antibiotic density than the layer and cattle farms did. After assessed, a few antibiotics (oxytetracycline, chlorotetracycline and tetracycline) have posed high ecological risks to soil around the farms. However, none of them caused hazard quotient (HQ) risk and carcinogenic risk (CR) to human health in the water of reservoir. Children were more likely to be at hazard risk than adults. Antibiotic mass fluctuation rules were analyzed along the chain (feed → livestock waste → soil → surface water). Feed, livestock waste and soil had similar diversity, but the antibiotic concentrations continued to decline, implying the possible sources of antibiotic residues were similar. Thus, it is important to reduce unnecessary antibiotic use to prevent the potential long-term risk of antibiotics.

Antibiotic resistance in the aquatic environment: Analytical techniques and interactive impact of emerging contaminants

Antibiotic pollution is becoming an increasingly severe threat globally. Antibiotics have emerged as a new class of environmental pollutants due to their expanding usage and indiscriminate application in animal husbandry as growth boosters. Contamination of aquatic ecosystems by antibiotics can have a variety of negative impacts on the microbial flora of these water bodies, as well as lead to the development and spread of antibiotic-resistant genes. Various strategies for removing antibiotics from aqueous systems and environments have been developed. Many of these approaches, however, are constrained by their high operating costs and the generation of secondary pollutants. This review aims to summarize research on the distribution and effects of antibiotics in aquatic environments, their interaction with other emerging contaminants, and their remediation strategy. The ecological risks associated with antibiotics in aquatic ecosystems and the need for more effective monitoring and detection system are also highlighted.

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

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

Determination of antimicrobial agents and their transformation products in an agricultural water-soil system modified with manure

Manure fertilization is the primary source of veterinary antimicrobials in the water-soil system. The research gap is the fate of antimicrobials after their release into the environment. This study aimed to provide a detailed and multi-faceted examination of fertilized cultivated fields using two types of manure (poultry and bovine) enriched with selected antimicrobials. The research focused on assessing the mobility and stability of antimicrobials in the water-soil system. Additionally, transformation products of antimicrobials in the environment were identified. The extraction (solid-phase extraction and/or solid-liquid extraction) and LC-MS/MS analysis procedures were developed to determine 14 antimicrobials in the soil and pore water samples. Ten out of fourteen antimicrobials were detected in manure-amended soil and pore water samples. The highest concentration in the soil was 109.1 ng g^-1 (doxycycline), while in pore water, it was 186.6 ng L^-1 (ciprofloxacin). Sixteen transformation products of antimicrobials were identified in the soil and soil-related pore water. The same transformation products were detected in both soil and soil pore water extracts, with significantly higher signal intensities observed in soil extracts than in water. Transformation products were formed in oxidation, carbonylation, and ring-opening reactions.

Global groundwater vulnerability for Pharmaceutical and Personal care products (PPCPs): The scenario of second decade of 21st century

The global production of PPCPs have increased by multiple folds promoting excessive exposure of its metabolites to humans via different aquatic systems. The higher residence time of toxic precursors of these metabolites pose direct human health risk. Among the different aquatic systems, the contamination of groundwater by PPCPs is the most concerning threat. This threat is especially critical considering the lesser oxidizing potential of the groundwater as compared to freshwater/river water. A major challenge also arises due to excessive dependency of the world's population on groundwater, which is exponentially increasing with time. This makes the identification and characterization of spatial contamination hotspots highly probabilistic as compared to other freshwater systems. The situation is more vulnerable in developing countries where there is a reported inadequacy of wastewater treatment facilities, thereby forcing the groundwater to behave as the only available sequestrating sink for all these contaminants. With increased consumption of antibiotics and other pharmaceuticals compounds, these wastes have proven capability in terms of enhancing the resistance among the biotic community of the soil systems, which ultimately can become catastrophic and carcinogenic in near future. Recent studies are supporting the aforementioned concern where compounds like diclofenac (analgesic) have attained a concentration of 1.3 mgL^-1 in the aquifer systems of Delhi, India. The situation is far worse for developed nations where prolonged and indiscriminate usage of antidepressants and antibiotics have life threating consequences. It has been confirmed that certain compounds like ofloxacin (antibiotics) and bis-(2-ethylhexyl)phthalate are present in some of the most sensitive wells/springs of the United States and Mexico. The current trend of the situation has been demonstrated by integrating a comparative approach of the published literatures in last three years. This review provides first-hand information report for formulating a directive policy framework for tackling PPCPs issues in the groundwater system.

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

Intensive use of antibiotics affects biogeochemical cycles and stimulates the evolution of antibiotic resistance, thus threatening global health and social development. The spatiotemporal distributions of antibiotics in single aqueous matrices have been widely documented; however, their occurrence in surface-groundwater systems has received less attention, especially in arid regions that usually have fragile ecosystems. Therefore, we investigated the occurrence of thirty-one antibiotics in the surface water and adjacent groundwater in the Xinjiang Uygur Autonomous Region, China. The results showed that the total concentrations of detected antibiotics varied from 17.37 to 84.09 ng L^-1 and from 16.38 to 277.41 ng L^-1 in surface and groundwater, respectively. The median concentration of antibiotics showed the pattern of norfloxacin (4.86 ng L^-1) > ciprofloxacin (3.93 ng L^-1) > pefloxacin (3.39 ng L^-1) in surface water; whereas in groundwater, this was in the order of pefloxacin (6.30 ng L^-1) > norfloxacin (4.33 ng L^-1) > ciprofloxacin (2.68 ng L^-1). Heatmap analysis indicated that vertical infiltration had limited effects on antibiotic exchange in surface-ground water systems because of the high potential evaporation and low water storage. Redundancy analysis suggested that the oxidation-reduction potential (p < 0.01) and dissolved oxygen (p < 0.05) jointly affected the distribution of antibiotics in surface water. Ecological risk assessment showed that antibiotics in 98.9% of surface water and 99.1% of groundwater did not pose significant risks to aquatic species. The findings of this study will help develop effective mitigation strategies for antibiotics in aquatic environments.

Global review of macrolide antibiotics in the aquatic environment: Sources, occurrence, fate, ecotoxicity, and risk assessment

The extensive use of macrolide antibiotics (MCLs) has led to their frequent detection in aquatic environments, affecting water quality and ecological health. In this study, the sources, global distribution, environmental fate, ecotoxicity and global risk assessment of MCLs were analyzed based on recently published literature. The results revealed that there are eight main sources of MCLs in the water environment. These pollution sources resulted in MCL detection at average or median concentrations of up to 3847 ng/L, and the most polluted water bodies were the receiving waters of wastewater treatment plants (WWTPs) and densely inhabited areas. Considering the environmental fate, adsorption, indirect photodegradation, and bioremoval may be the main attenuation mechanisms in natural water environments. N-demethylation, O-demethylation, sugar and side chain loss from MCL molecules were the main pathways of MCLs photodegradation. Demethylation, phosphorylation, N-oxidation, lactone ring hydrolysis, and sugar loss were the main biodegradation pathways. The median effective concentration values of MCLs for microalgae, crustaceans, fish, and invertebrates were 0.21, 39.30, 106.42, and 28.00 mg/L, respectively. MCLs induced the generation of reactive oxygen species, that caused oxidative stress to biomolecules, and affected gene expression related to photosynthesis, energy metabolism, DNA replication, and repair. Moreover, over 50% of the reported water bodies represented a medium to high risk to microalgae. Further studies on the development of tertiary treatment technologies for antibiotic removal in WWTPs, the combined ecotoxicity of antibiotic mixtures at environmental concentration levels, and the development of accurate ecological risk assessment models should be encouraged.

Insights into the occurrence, elimination efficiency and ecological risk of antibiotics in rural domestic wastewater treatment facilities along the Yangtze River Basin, China

China is embarking on the treatment of rural domestic wastewater, but little information on the characteristics of antibiotics in the rural domestic wastewater is available. As one of the most important new-emerging pollutants, antibiotic has been explicitly proposed to be controlled and treated since the fifth plenary session of the 19th Central Committee of the Communist Party of China. Thus, the occurrence, elimination efficiency and ecological risk of antibiotics, as well as conventional wastewater quality parameters were investigated in influents and effluents from 41 rural domestic wastewater treatment facilities (RD-WWTFs) along the Yangtze River Basin. Results showed that elimination efficiencies of routinely monitored conventional pollutants in 33 RD-WWTFs (accounting for 80.5%) were effective based on conventional wastewater quality parameters. Of 39 target antibiotics selected, 26 ones were detected in the influents and effluents with a detection frequency (DF) between 2.4% and 100%. No significant decrease of antibiotics was observed in the effluents compared with that in the influents except chlortetracyclin (CTE) and tetracycline (TCs). The composition characteristics of antibiotics showed regional differences. Among the investigated antibiotics, ofloxacin (OFX), doxycycline (DOX), roxithromycin (ROX) and lincomycin (LIN) were the predominant, totally accounted for a median percentage of more than 60% of ΣAB concentrations in both influents and effluents. Ecological risk values of ΣABs showed that 11 effluents presented high risks (26.8%), 18 ones had moderate risks (43.9%), and the rest 12 ones showed low risks (29.3%). Moreover, oxytetracycline (OXY), norfloxacin (NOR), LIN and ROX was the dominant contributors to the ecological risk values. Overall, the elimination effect of antibiotics was limited in RD-WWTFs along the Yangtze River Basin, which was likely to pose potential adverse impacts on aquatic ecosystems.

Comprehensive insights into profiles and bacterial sources of intracellular and extracellular antibiotic resistance genes in groundwater

Antibiotic resistance genes (ARGs), especially last-resort ARGs (LARGs), are receiving extensive attention as emerging environmental contaminants in groundwater. However, their prevalent intracellular and extracellular patterns and bacterial sources in groundwater remain unclear. Herein, groundwater samples were collected in Tianjin, and characterized based on the profiles of intracellular ARGs (iARGs) and extracellular ARGs (eARGs), as well as the resident bacterial communities and extracellular DNA (eDNA)-releasing bacterial communities. The quantitative real-time PCR assays showed that eARGs presented fewer subtypes than iARGs and generally displayed lower detection frequencies than the corresponding iARGs. Similarly, LARGs exhibited lower detection frequencies than common ARGs, but the total abundance showed no significant differences between them. Genes vanA and bla_VIM were the observed dominant LARGs, and aadA was the observed common ARG independent of location inside or outside the bacteria. Furthermore, the top 10 phyla showed much difference between the main eDNA-releasing bacteria and the dominant resident bacteria. Proteobacteria was the predominant resident bacterial phyla while dominating the source of eDNA in groundwater. Despite representing a minor portion of the abundance in the resident bacteria, Actinobacteriota, Acidobacteriota, and Chloroflex surprisingly accounted for a large majority of eDNA release. Co-occurrence patterns among persistent ARGs, the resident bacteria, and eDNA-releasing bacteria revealed that the dominant common iARG aadA and intracellular LARGs bla_VIM and vanA had significant positive correlations with Methylobacterium_Methylorubrum and Shewanella. Meanwhile, the dominant extracellular LARG bla_VIM may be released by bacteria belonging to at least five genera, including Ellin6067, Bifidobacterium, Blautia, Veillonella, and Dechloromonas. Collectively, the findings of this study extend our understanding regarding the distribution of ARGs and their bacterial sources in groundwater, and indicate the serious pollution of LARGs in groundwater, which poses potential risks to public health.

Uptake and accumulation of erythromycin in leafy vegetables and induced phytotoxicity and dietary risks

Erythromycin (ERY), a widely used macrolide antibiotic, is omnipresent in soil and aquatic environments, which may potentially contaminate food crops but remains to be explored. Two leafy vegetables, pakchoi (Brassica rapa subsp. chinensis) and water spinach (Ipomoea aquatica Forsk.), were grown in laboratory-constructed soil or hydroponic systems to investigate the dynamic accumulation of ERY in edible plants. Results indicate ¹⁴C-ERY could be absorbed by water spinach and pakchoi in both systems. Autoradiographic imaging and concentration data of plant tissues suggested that ERY had limited translocation from roots to shoots in these two vegetables. The accumulation level of ERY was similar between the two vegetables in the soil system; but in the hydroponic system, pakchoi had a higher ERY accumulation than water spinach, with the bioconcentration factor of 2.74-25.98 and 3.65-11.67 L kg^-1, respectively. The ERY intake via vegetable consumption was 0.01-2.17 ng kg^-1 day^-1, which was much lower than the maximum acceptable daily intake (700 ng kg^-1 day^-1), indicating negligible risks of consuming vegetables with roots exposed to ERY at environmentally relevant levels. In addition, ERY was found to cause growth inhibition and oxidative stress to pakchoi, even at low concentrations (7 and 22 μg L^-1). This work contributes to a better understanding of plant uptake and translocation of ERY in soils and water, and has important implications for the reasonable evaluation of the implied risks of ERY to vegetables and human health.

Fluidized ZnO@BCFPs Particle Electrodes for Efficient Degradation and Detoxification of Metronidazole in 3D Electro-Peroxone Process

A novel material of self-shaped ZnO-embedded biomass carbon foam pellets (ZnO@BCFPs) was successfully synthesized and used as fluidized particle electrodes in three-dimensional (3D) electro-peroxone systems for metronidazole degradation. Compared with 3D and 2D + O₃ systems, the energy consumption was greatly reduced and the removal efficiencies of metronidazole were improved in the 3D + O₃ system. The degradation rate constants increased from 0.0369 min^-1 and 0.0337 min^-1 to 0.0553 min^-1, respectively. The removal efficiencies of metronidazole and total organic carbon reached 100% and 50.5% within 60 min under optimal conditions. It indicated that adding ZnO@BCFPs particle electrodes was beneficial to simultaneous adsorption and degradation of metronidazole due to improving mass transfer of metronidazole and forming numerous tiny electrolytic cells. In addition, the process of metronidazole degradation in 3D electro-peroxone systems involved hydroxyethyl cleavage, hydroxylation, nitro-reduction, N-denitrification and ring-opening. The active species of ·OH and ·O₂^- played an important role. Furthermore, the acute toxicity LD₅₀ and the bioconcentration factor of intermediate products decreased with the increasing reaction time.

Spatiotemporal variations and ecological risks of typical antibiotics in rivers inflowing into Taihu Lake, China

Antibiotics have become a global public concern due to the widespread presence of antibiotic-resistant bacteria and genes. This study investigated the spatial and seasonal variation of conventional water quality parameters and 10 selected antibiotics in rivers inflowing into Taihu Lake. The results showed that total nitrogen, as a pollution driver factor, varied with the seasons, and higher concentrations of pollutants were generally found in the dry season compared with the wet season. For antibiotics, seven of them were detected in surface waters (n = 66) with detection frequencies (DFs) of 1.52-100% and eight antibiotics with DFs of 2.56-100% in sediments (n = 39). Sulfamethoxazole (SMZ, median: 1.47 ng/L), trimethoprim (TMP, median: 0.35 ng/L), and roxithromycin (ROX, median: 0.47 ng/L) with 100% DFs followed by erythromycin (ERY, median: 0.56 ng/L) with a DF of 90.91% accounted for a median percentage of 44.54%, 9.08%, 20.42%, and 13.16% of the ΣABs concentrations in surface waters. In contrast, enrofloxacin (ENR, median: 0.54 ng/g) and ROX (median: 0.29 ng/g) with 100% DFs accounted for a median percentage of 58.21% and 31.71% of the ΣABs concentrations in sediments. Antibiotics in surface waters were mainly related to T, DO, TN and NH₃-N, but were mainly related to T, pH and TN for antibiotics in sediments. Furthermore, most of the detected antibiotics showed higher concentrations and more species of antibiotics in winter than in summer or autumn. Similarly, the ecological risk values of antibiotics showed higher in winter than in the other two seasons, whereas the overall risk levels were considered acceptable.

Occurrence, source apportionment and potential risks of selected PPCPs in groundwater used as a source of drinking water from key urban-rural settings of Pakistan

BACKGROUND

Pharmaceuticals and personal care products (PPCPs) are emerging contaminants that have been extensively used in present time to improve the living standards. Their persistence in water resources due to various anthropogenic sources such as wastewater treatment plants, pharmaceutical industries, and runoff from agricultural and livestock farms has not only threaten aquatic life but their occurrence in groundwater has also raised concerns related to humans' wellbeing.

METHODS

Considering this as a neglected area of research in Pakistan, a systematic monitoring study was designed to investigate their occurrence, sources, and potential environmental and human health risks in groundwater from urban-rural areas of six cities. Ultra-High-Performance Liquid Chromatography-Tandem Mass Spectrometry (UHPLC-MS/MS) was used to analyze the collected samples preceded by solid-phase extraction.

RESULTS

Overall, 8 out of 11 selected PPCPs were detected in groundwater samples with detection frequency ranging from 5.5-65%. Their concentrations ranged from below limit of detection (<LOD) to 1961 ng/L. The overall mean concentrations of detected PPCPs were found below 100 ng/L. The highest mean concentration was reported for Ibuprofen (154 ng/L) in Rawalpindi/Islamabad. Results of PCA-MLR revealed that domestic wastewater discharge (76.4%) was the dominant source contributing to PPCPs contamination in groundwater. Followed by mixed source (pharmaceutical & hospital waste) 17.8%, and rural discharge/animal husbandry 5.8%. No appreciable risk to human health upon exposure to detected PPCPs via drinking water was anticipated. However, environmental risk assessment indicated moderate risk posed to P. subcapitata (RQ = 0.98) and D. magna (RQ = 0.2) by ibuprofen.

CONCLUSION

The current study reports the first evidence of PPCPs occurrence in groundwater in Pakistan. Reporting their occurrence in groundwater is a fundamental initial step to inform public-health decisions concerning sewage systems and drinking water quality. Hence, comprehensive monitoring programs are required to further investigate contamination of emerging contaminants in groundwater and their associated risks.

Occurrence and risk assessment of antibiotics in the surface water of Chaohu Lake and its tributaries in China

The extensive use of antibiotics for treating humans, animals, and plants has resulted in the contamination of aquatic environments, posing a potential threat to public health and aquatic life; hence, this topic is of great concern worldwide. Lakes are considered to be antibiotic-rich reservoirs because many of the antibiotics discharged from rivers enter lakes. Chaohu Lake is one of the top five freshwater lakes in China. This study aims to provide a current evaluation of the antibiotics present in the surface water of the Chaohu Lake basin. To this end, the occurrences of 18 antibiotics categorized into 5 different groups were investigated in the study area, and the impact of inflowing rivers on their distribution was assessed. The results showed that the concentrations of 14 antibiotics in water samples ranged from 0 to 892 ng/L, and that antibiotics were detected at most sampling sites. Among them, the Nanfeihe and Shiwulihe rivers, which are close to the city, contributed the most to antibiotic pollution, indicating the widespread occurrence of antibiotics in the study area. A risk assessment based on the risk quotient method indicated that ofloxacin, ciprofloxacin, sulfamethoxazole, erythromycin, and norfloxacin in the lake water posed a high ecological risk to algae, while sulfamethazine posed a high risk to plants (RQ >1).

Biochar-Supported TiO2-Based Nanocomposites for the Photocatalytic Degradation of Sulfamethoxazole in Water-A Review

Sulfamethoxazole (SMX) is a frequently used antibiotic for the treatment of urinary tract, respiratory, and intestinal infections and as a supplement in livestock or fishery farming to boost production. The release of SMX into the environment can lead to the development of antibiotic resistance among the microbial community, which can lead to frequent clinical infections. SMX removal from water is usually done through advanced treatment processes, such as adsorption, photocatalytic oxidation, and biodegradation. Among them, the advanced oxidation process using TiO2 and its composites is being widely used. TiO2 is a widely used photocatalyst; however, it has certain limitations, such as low visible light response and quick recombination of e-/h+ pairs. Integrating the biochar with TiO2 nanoparticles can overcome such limitations. The biochar-supported TiO2 composites showed a significant increase in the photocatalytic activities in the UV-visible range, which resulted in a substantial increase in the degradation of SMX in water. The present review has critically reviewed the methods of biochar TiO2 composite synthesis, the effect of biochar integration with the TiO2 on its physicochemical properties, and the chemical pathways through which the biochar/TiO2 composite degrades the SMX in water or aqueous solution. The degradation of SMX using photocatalysis can be considered a useful model, and the research studies presented in this review will allow extending this area of research on other types of similar pharmaceuticals or pollutants in general in the future.