Occurrence, source apportionment and risk assessment of antibiotics in water and sediment from the subtropical Beibu Gulf, South China

Simultaneous analysis of multi-class antibiotics in bottled water using large-volume direct-injection LC-MS/MS

A large-volume direct-injection (LVDI) method was developed and validated for the simultaneous analysis of 69 antibiotics in bottled water using ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Target antibiotics included 23 sulfonamides, 19 quinolones, 12 macrolides, 11 β-lactams, and 4 tetracyclines. Optimization of ion source parameters led to enhanced signal intensities for 55 antibiotics. The 100 μL injection volume was both feasible and preferred, resulting in increased signal intensities while maintaining unchanged peak shapes for the antibiotics. Good absolute recoveries for the 69 antibiotics were obtained with the LVDI method, primarily ranging from 80% to 120%, whereas lower absolute recoveries of macrolides, quinolones, sulfonamides and β-lactams were observed with a solid-phase extraction (SPE) method. The limits of detection (LODs) for antibiotics were generally comparable between the LVDI and SPE methods, with values below 1 ng L-1 for most antibiotics (0.00271-26.6 ng L-1). Analysis of 25 brands of bottled water using the LVDI method revealed the presence of 54 antibiotics from 5 classes, with detection frequencies (DFs) ranging from 4% to 100% and detected concentrations between 0.0453 and 37.4 ng L-1. Multiple antibiotics were detected simultaneously in bottled water, with more than 10 antibiotics identified in each of 9 different brands. Quinolones and sulfonamides were the predominant antibiotics, accounting for over 80% of the total concentration. Only sulfaclozine showed significantly different concentrations between purified drinking water and natural mineral water (22.2 vs. 17.2 ng L-1, p < 0.05).

Multimedia contamination characteristics, risk assessment, and source quantification of phthalates in the Shaying River Basin, China

Phthalates (PAEs), a class of typical endocrine-disrupting chemicals, have been widely detected in the environment due to their prevalent use as plasticizers in plastic products. This study investigates the multimedia contamination characteristics and potential ecological risks of PAEs in water, soil, and sediments of the Shaying River (SYR) Basin. A Geodetector model (GDM) was employed to identify the key drivers influencing the spatial distribution of PAEs, while factor analysis and the Positive Matrix Factorization (PMF) model were utilized to quantitatively apportion the potential sources of PAEs. Results revealed that the concentrations and spatial variation of PAEs were significantly higher in soil and sediments than in water, with distinct compositional profiles. Water samples exhibited a higher proportion of low-molecular-weight PAEs compared to soil and sediment, where high-molecular-weight PAEs prevailed to a lesser extent. Notably, among the 6 target PAEs, di-n-butyl phthalate (DBP) and di-(2-ethylhexyl) phthalate (DEHP) were uniformly the primary PAEs in water, soil, and sediment of the SYR Basin, posing higher ecological risks to algae, crustaceans, amphibians, and fish compared to the other 4 PAEs. The spatial distribution of PAEs in the SYR Basin was comprehensively influenced by land use, precipitation, human activities, and soil types. Key factors vary across media, but the interaction between popdensity and other variables significantly enhanced the interpretation degree, jointly shaping the PAEs distribution patterns. Primary sources of PAEs in the basin were sewage and wastewater discharges (37.0%), nonpoint industrial sources (36.4%), and domestic sources (25.6%).

Trophic transfer of sulfonamide antibiotics in aquatic food chains: A comprehensive review with a focus on environmental health risks

Antibiotics, which have been identified as emerged pollutants, are creating an increase in environmental concerns, with sulfonamide antibiotics (SAs) being among the most commonly discovered antibiotics. Due to their widespread usage and inadequate sewage treatment, SAs are frequently released into the aquatic environment. The introduction of SAs into aquatic environments can kill or inhibit the growth or metabolic activity of microorganisms, thereby affecting biological communities and ecological functions and disrupting the equilibrium of aquatic ecosystems. The transmission of SAs to human beings can occur through trophic transfer of food chains, particularly when humans consume aquatic food. This study examines the trophic transfer of SAs along the aquatic food chain, provides a summarize of the spatial distribution of SAs in aquatic environments, and evaluates the environmental risks associated with it. The prevalence of SAs was predominantly noted in the aqueous phase, with relatively lower concentrations detected in sediments, solidifying their status as one of the most widespread antibiotics among aquatic organisms. SAs, characterized by their high biomagnification capacity and strong bioaccumulative properties in invertebrates, emerge as the antibiotic type with the greatest ecological risks. The ecological risk posed by sulfonamide antibiotics to aquatic organisms is more pronounced than the health risk to humans, suggesting that the adverse effects on aquatic life warrant greater attention. Additionally, this study offers practical recommendations to address the limitations of previous research, emphasizing the importance of regulating exposure and establishing a robust health risk prediction system as effective measures for antibiotic control.

Integrative oxidative stress biomarkers in gills and digestive gland of the combined exposure to citalopram and bezafibrate with polyethylene microplastics on mussels Mytilus galloprovincialis

Pharmaceutical active compounds (PhACs) and microplastics (MPs) have been detected in different marine compartments from coastal areas, raising concerns due to their simultaneous discharge through wastewater treatment plants (WWTPs) and the role of MPs as vectors of pollutants for marine organisms. This study investigates the biochemical effects of citalopram (CIT) and bezafibrate (BEZ) on the mussel Mytilus galloprovincialis, at environmentally relevant concentrations, and their co-exposure with high-density polyethylene (HDPE) MPs. MPs accumulated in gills and digestive glands during exposure, but they were rapidly eliminated after depuration, except for a small fraction of the smallest MPs in gills. This study evaluated the biological effects in gills and digestive gland, and confirmed CIT induced oxidative stress in both tissues, exacerbated by the presence of MPs. BEZ, despite not being detected at high concentrations in the mussel tissues, activated an antioxidant response in gills and increasing the transcription of the genes Se-gpx and gst-pi in digestive gland. Both PhACs impaired the cholinergic pathway long-term, even after the depuration period, as indicated by decreased AChE levels in the gills, suggesting potential neurotoxic effects after prolonged exposure. Consequently, adverse effects were provoked by both PhACs with (CIT) and without (BEZ) significant bioaccumulation capacity.

Occurrences, source apportionment, and potential risks of 55 progestins in surface water of the Yellow River Delta, China

Progestins (PGs) are a group of emerging contaminants with endocrine disrupting effects. Despite their large amounts of use and excretion, investigations have been limited to several compounds in the aqueous phase, and the occurrences and distribution of numerous PGs in different matrices remain unclear. In this study, water, suspended particulate matter and sediment samples from rivers in the Yellow River Delta (YRD), China were investigated over two seasons to elucidate the occurrences, sources, and ecological risks of 55 natural and synthetic PGs. 40 PGs were detected with concentrations varied from not detected (ND) to 146 ng/L in water, ND to 251 ng/g dry weight (dw) in SPM, and ND-173 ng/g dw in sediment. The less-studied natural metabolites were the predominant PGs in all samples. 54-96 % of the PGs were concentrated in the aqueous phase, and SPM was also an important carrier, especially for hydrophobic compounds. Anthropogenic activities and environmental conditions together affected the spatiotemporal distribution of PGs. Animal sources, including aquaculture and animal husbandry, contributed most (42.3 %) to the total PGs, followed by treated sewage (32.9 %) and industrial sources (24.7 %). The risk assessment suggested that PGs posed moderate to high risks to aquatic organisms, especially the fish.

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.

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

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

Dissolved PAHs in the Beibu Gulf and adjacent waters of the South China Sea: Physical and biochemical processes-driven distributional variations

Polycyclic aromatic hydrocarbons (PAHs) in semi-enclosed gulfs are influenced by physical and biochemical processes, which haven't been well understood. This study aims to investigate the spatial distribution and vertical profiles of dissolved PAHs in the Beibu Gulf (BG) and adjacent waters of the South China Sea, along with hydrological, meteorological, and biochemical variables. Particularly relevant are the effects of atmospheric pressure, salinity, ammonium, chlorophyll-a, as well as riverine inputs (RI), sea currents, and upwelling. In surface seawater, the total concentrations of eight dissolved PAHs (∑8PAHs) were 7.76 ± 2.16 ng/L, with a distribution pattern of western Guangdong waters (WGWs) > BG > Qiongzhou Strait (QS). ∑8PAHs in the northern BG (9.10 ± 2.00 ng/L) was significantly higher than that in the southern BG (6.65 ± 1.54 ng/L) (p < 0.01), suggesting that local anthropogenic activities and unique environmental characteristics significantly influenced PAHs distribution. In water column, PAHs in BG displayed enrichment in surface and bottom but decreased in medium water, while those in WGWs and QS decreased with increasing depth. Source apportionment concluded that PAHs in QS and WGWs were primarily from petroleum sources, and PAHs in BG were mainly from coal combustion. RI, combined with circulation, coastal current, and intrusion of SCS water influenced the surface PAHs distribution in BG, with eddy impacts observed. Specifically, regarding the surface PAHs distribution, differences in atmospheric pressure may influence the air-sea exchange of PAHs, especially positively affecting 4-ring PAHs. Salinity factors further corroborated the contribution of RI to 3-ring PAHs, followed by the regulation of PAHs through biological pumps (ammonia and chlorophyll-a). Moreover, upwelling-induced biodegradation and resuspension affected the vertical distribution of PAHs. While most PAHs posed a negligible risk, coking-generated fluorene posed a moderate risk to ecosystems due to changes in the energy structure, warranting further investigation into its toxicological impacts.

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

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

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

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

Spatiotemporal distribution patterns and coupling effects of aquatic environmental factors in the dry-wet season over a decade from the Beibu Gulf, South China Sea

Since the 21st century, the Beibu Gulf area has been affected by increasing anthropogenic activities, which makes the coastal aquatic ecosystem extremely concerning. However, the comprehensive exploration and analysis of the long-term scale behavior change characteristics of various water quality environment factors is still limited. Through comprehensively detecting coastal surface water environmental behavior information from 33 locations in the Beibu Gulf from 2005 to 2015, we revealed and quantified mutual response characteristics and patterns of various environmental indicators. The main environmental pollution indicators (e.g., COD, NH4+, NO3-, and DIP) showed a gradual decrease in concentration from the coast to the offshore sea area, and significantly increases during the wet season. The semi-enclosed Maowei Sea exhibited the most prominent performance with significant differences compared to other regions in Beibu Gulf. The average Chlorophyll-a (Chla) content in the coastal area of the Beibu Gulf during the wet season was more than twice that of the dry season, yet the interaction pattern between Chla and environmental factors in the two seasons was opposite to its concentration behavior, accompanied by a closely significant relationship with thermohaline structure and the input of nitrogen and phosphorous nutrients. The multivariate statistical analysis results of total nutrient dynamics suggested that the Beibu Gulf was clearly divided into different regions in both dry and wet season clusters. The present study can provide a comprehensive perspective for the spatial and temporal migration patterns and transformation laws of coastal water environmental factor, which should contribute to improve the prevention countermeasure of nutrient pollution in coastal environment.

Fine particulate matter as a key factor promoting the spread of antibiotics in river network

The extensive utilization of antibiotics has resulted in their frequent detection, contributing to an increased abundance of antibiotic resistance genes in rivers and posing a significant threat to environmental health. Particulate matter plays a crucial role as the primary carrier of various pollutants in river ecosystem. Its physicochemical properties and processes of sedimentation and re-suspension can influence the migration and transformation of antibiotics, yet the mechanisms of this impact remain unclear. In this study, we investigated the distribution characteristics at the micro-scale of particles in the upstream plain river network of the Taihu basin and the adsorption behaviors of antibiotics in particulate matter. The results revealed that particles were predominantly in the size range of 30 to 150 μm in the river network and highest total antibiotic concentrations in 0 to 10 μm particle size fractions. Adsorption experiments also confirmed that the smaller the suspended particle size, the stronger the adsorption capacity for antibiotics. Spatially, both the average particle size and total antibiotic concentrations were lower downstream than upstream. The distribution mechanism of antibiotic in river network sediments was significantly influenced by frequent resuspension and settling of fine particles with a stronger capacity to adsorb antibiotics under hydrodynamic conditions. This ultimately facilitated the release of antibiotics from sediment into the water, resulting in lower antibiotic concentrations in downstream sediments relative to upstream These findings suggest that fine particles serve as the primary carriers of antibiotics, and their sorting and transport processes can significantly influence the distribution of antibiotics in water-sediment systems. This study enhances our understanding of the migration mechanisms of antibiotics in river networks and will prove beneficial for the development of management strategies aimed at controlling antibiotic dissemination.

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.

Alien emergent aquatic plants develop better ciprofloxacin tolerance and metabolic capacity than one native submerged species

Antibiotic pollution and biological invasion pose significant risks to freshwater biodiversity and ecosystem health. However, few studies have compared the ecological adaptability and ciprofloxacin (CIPR) degradation potential between alien and native macrophytes. We examined growth, physiological response, and CIPR accumulation, translocation and metabolic abilities of two alien plants (Eichhornia crassipes and Myriophyllum aquaticum) and one native submerged species (Vallisneria natans) exposed to CIPR at 0, 1 and 10 mg/L. We found that E. crassipes and M. aquaticum's growth were unaffected by CIPR while V. natans was significantly hindered under the 10 mg/L treatment. CIPR significantly decreased the maximal quantum yield of PSII, actual quantum yield of PSII and relative electron transfer rate in E. crassipes and V. natans but didn't impact these photosynthetic characteristics in M. aquaticum. All the plants can accumulate, translocate and metabolize CIPR. M. aquaticum and E. crassipes in the 10 mg/L treatment group showed greater CIPR accumulation potential than V. natans indicated by higher CIPR contents in their roots. The oxidative cleavage of the piperazine ring acts as a key pathway for these aquatic plants to metabolize CIPR and the metabolites mainly distributed in plant roots. M. aquaticum and E. crassipes showed a higher production of CIPR metabolites compared to V. natans, with M. aquaticum exhibiting the strongest CIPR metabolic ability, as indicated by the most extensive structural breakdown of CIPR and the largest number of potential metabolic pathways. Taken together, alien species outperformed the native species in ecological adaptability, CIPR accumulation and metabolic capacity. These findings may shed light on the successful invasion mechanisms of alien aquatic species under antibiotic pressure and highlight the potential ecological impacts of alien species, particularly M. aquaticum. Additionally, the interaction of antibiotic contamination and invasion might further challenge the native submerged macrophytes and pose greater risks to freshwater ecosystems.

Antibiotics in the rice-crayfish rotation pattern: Occurrence, prioritization, and resistance risk

Antibiotics are extensively utilized in aquaculture to mitigate diseases and augment the productivity of aquatic commodities. However, to date, there have been no reports on the presence and associated risks of antibiotics in the emergent rice-crayfish rotation (RCR) system. This study investigated the occurrence, temporal dynamics, prioritization, sources, and potential for resistance development of 15 antibiotics within the RCR ecosystem. The findings revealed that during the crayfish breeding and rice planting periods, florfenicol (FFC) predominated in the RCR's surface water, with peak and average concentrations of 1219.70 ng/L and 57.43 ng/L, and 1280.70 ng/L and 52.60 ng/L, respectively. Meanwhile, enrofloxacin (ENX) was the primary antibiotic detected in RCR soil and its maximum and average concentrations were 624.73 ng/L and 69.02 ng/L in the crayfish breeding period, and 871.27 ng/L and 45.89 ng/L in the rice planting period. Throughout the adjustment period, antibiotic concentrations remained relatively stable in both phases. Notably, antibiotic levels in surface water and soil escalated during the crayfish breeding period and subsided during the rice planting period, with these fluctuations predominantly influenced by FFC and ENX. Source analysis indicated that the antibiotics in RCR predominantly originated from aquaculture activities, supplemented by water exchange processes. Utilizing the entropy utility function and a resistance development model, FFC, clarithromycin (CLR), and roxithromycin (ROX) in surface water, along with ENX, CLR, and ROX in soil, were identified as priority antibiotics. FFC, ENX, and ROX exhibited a medium risk for resistance development. Consequently, this study underscores the necessity to intensify antibiotic usage control during the crayfish breeding period in the RCR system to mitigate environmental risks.

A meta-analysis of antibiotic residues in the Beibu Gulf

Antibiotic residue stands as a significant ongoing environmental issue, with aquaculture being a major source of annual antibiotic discharge into the ocean. Nevertheless, there is still an incomplete evaluation of antibiotic residues in the Beibu Gulf, an area encompassed by two prominent aquaculture nations, China and Vietnam. The present systematic review and meta-analysis was conducted to examine the presence antibiotic residues in the Beibu Gulf based on published studies. Data were obtained through eight databases up to December 19th, 2023, and were updated on April 15th, 2024. The pooled concentration of antibiotic residues in seawater was 5.90 (ng/L), ranging from 5.73 to 6.06 (ng/L), and was 8.03 (ng/g), ranging from 7.77 to 8.28 (ng/g) in sediments. Fluoroquinolones, tetracyclines, and macrolides were identified as the main antibiotics found in both seawater and sediment samples. The Beibu Gulf showed higher antibiotic levels in its western and northeastern areas. Additionally, the nearshore mangrove areas displayed the highest prevalence of antibiotic residues. It is strongly advised to conduct regular long-term monitoring of antibiotic residues in the Beibu Gulf. Collaborative surveys covering the entire Beibu Gulf involving China and Vietnam are recommended.

Effects of antibiotics on microbial nitrogen cycling and N2O emissions: A review

Sulfonamides, quinolones, tetracyclines, and macrolides are the most prevalent classes of antibiotics used in both medical treatment and agriculture. The misuse of antibiotics leads to their extensive dissemination in the environment. These antibiotics can modify the structure and functionality of microbial communities, consequently impacting microbial-mediated nitrogen cycling processes including nitrification, denitrification, and anammox. They can change the relative abundance of nirK/norB contributing to the emission of nitrous oxide, a potent greenhouse gas. This review provides a comprehensive examination of the presence of these four antibiotic classes across different environmental matrices and synthesizes current knowledge of their effects on the nitrogen cycle, including the underlying mechanisms. Such an overview is crucial for understanding the ecological impacts of antibiotics and for guiding future research directions. The presence of antibiotics in the environment varies widely, with significant differences in concentration and type across various settings. We conducted a comprehensive review of over 70 research articles that compare various aspects including processes, antibiotics, concentration ranges, microbial sources, experimental methods, and mechanisms of influence. Antibiotics can either inhibit, have no effect, or even stimulate nitrification, denitrification, and anammox, depending on the experimental conditions. The influence of antibiotics on the nitrogen cycle is characterized by dose-dependent responses, primarily inhibiting nitrification, denitrification, and anammox. This is achieved through alterations in microbial community composition and diversity, carbon source utilization, enzyme activities, electron transfer chain function, and the abundance of specific functional enzymes and antibiotic resistance genes. These alterations can lead to diminished removal of reactive nitrogen and heightened nitrous oxide emissions, potentially exacerbating the greenhouse effect and related environmental issues. Future research should consider diverse reaction mechanisms and expand the scope to investigate the combined effects of multiple antibiotics, as well as their interactions with heavy metals and other chemicals or organisms.

Occurrence and distribution of antibiotics and antibiotic resistance genes from the land to ocean in Daliao River-Liaodong Bay, China

In this study, the pollution status of antibiotics and ARGs in sediments from the land-sea intersection of Liaodong Bay was analyzed. The results showed that the level of antibiotic pollution ranged from ND to 433.27 ng/kg, with quinolones and tetracycline as the dominant antibiotics. The relative abundance of ARGs ranged from 3.62 × 10-3 to 1.32 × 10-1 copies/16SrRNA copies, with aminoglycoside and MLSB resistance genes being dominant. Regarding spatial distribution, the land and estuary areas showed higher antibiotic pollution levels than the offshore areas. Similarly, the land and estuary areas exhibited higher antibiotic diversity than the offshore areas. The ARGs were widely distributed on land, and their abundance gradually decreased to the downstream estuary area. Land and coastal areas exhibited higher ARG diversity than estuary areas. Analysis of environmental factors revealed a significant correlation between ARGs and non-corresponding antibiotics, and some ARGs were affected by heavy metals Cu and Pb.

Spatial distribution, mass flux, and ecological risk of antibiotics in Taiwan and Luzon Straits: A case in the West Pacific Region

Emerging pollutants are hazardous to the ecological environment and human health, and these issues have attracted increasing attention from scholars. In the current study, the Taiwan Strait is long and narrow, highly influenced by terrestrial domains, and frequently disturbed by human activities. Conversely, the Luzon Strait is an open sea far from the shore, and the impact of human activities on it is minimal. The description of antibiotics in two different types of seas revealed that contaminants were most commonly detected in both straits. In particular, the coasts of the Minjiang River, Jinjiang River, and Jiulong River were found to be pollution hotspots in the Taiwan Strait. The calculation of risk quotients revealed that antibiotics were more sensitive to algae. Furthermore, estimation of the risk quotients of the mixtures found that antibiotics in the environment do not pose a high risk to aquatic organisms at different trophic levels.

Source apportionment and predictable driving factors contribute to antibiotics profiles in Changshou Lake of the Three Gorges Reservoir area, China

Lakes, crucial antibiotic reservoirs, lack thorough exploration of quantitative relationships between antibiotics and influencing factors. Here, we conducted a comprehensive year-long investigation in Changshou Lake within the Three Gorges Reservoir area, China. The concentrations of 21 antibiotics spanned 35.6-200 ng/L, 50.3-348 ng/L and 0.57-57.9 ng/g in surface water, overlying water and sediment, respectively. Compared with abundant water period, surface water and overlying water displayed significantly high antibiotic concentrations in flat and low water periods, while sediment remained unchanged. Moreover, tetracyclines, fluoroquinolones and erythromycin posed notable risks to algae. Six primary sources were identified using positive matrix factorization model, with aquaculture contributing 21.2%, 22.7% and 25.4% in surface water, overlying water and sediment, respectively. The crucial predictors were screened through machine learning, redundancy analysis and Mantel test. Our findings emphasized the pivotal roles of water quality parameters, including water temperature (WT), pH, dissolved oxygen, electrical conductivity, inorganic anions (NO3⁻, Cl⁻ and F⁻) and metal cations (Ca, Mg, Fe, K and Cr), with WT influencing greatest. Total nitrogen (TN), cation exchange capacity, K, Al and Cd significantly impacted sediment antibiotics, with TN having the most pronounced effect. This study can promise valuable insights for environmental planning and policies addressing antibiotic pollution.

The "Microplastome" - A Holistic Perspective to Capture the Real-World Ecology of Microplastics

Microplastic pollution, an emerging pollution issue, has become a significant environmental concern globally due to its ubiquitous, persistent, complex, toxic, and ever-increasing nature. As a multifaceted and diverse suite of small plastic particles with different physicochemical properties and associated matters such as absorbed chemicals and microbes, future research on microplastics will need to comprehensively consider their multidimensional attributes. Here, we introduce a novel, conceptual framework of the "microplastome", defined as the entirety of various plastic particles (<5 mm), and their associated matters such as chemicals and microbes, found within a sample and its overall environmental and toxicological impacts. As a novel concept, this paper aims to emphasize and call for a collective quantification and characterization of microplastics and for a more holistic understanding regarding the differences, connections, and effects of microplastics in different biotic and abiotic ecosystem compartments. Deriving from this lens, we present our insights and prospective trajectories for characterization, risk assessment, and source apportionment of microplastics. We hope this new paradigm can guide and propel microplastic research toward a more holistic era and contribute to an informed strategy for combating this globally important environmental pollution issue.

Optimization and verification of selective removal of organophosphate esters from wastewater by molecularly imprinted adsorbent

Tributyl phosphate (TNBP), a new type of flame retardant, is an emerging pollutant and has been frequently detected in various matrices such as wastewater. Efficient removal of TNBP is critical for wastewater treatment. In this study, molecularly imprinted polymer (MIP) was prepared using precipitation polymerization for selective adsorption of TNBP. The results showed that MIP had a porous structure and formed effective imprinting cavities, which was primarily responsible for its superior adsorption ability. The adsorption of TNBP by MIP was carried out following both the pseudo-secondary kinetic model and the Langmuir isothermal adsorption model. MIP adsorbed TNBP rapidly and reached adsorption equilibrium within 30 min with 923 μmol g-1 at 298 K. The adsorption capacity and adsorption rate of MIP were respectively 2 and 5.49 times those of non-molecularly imprinted polymers. In addition, MIP could effectively counter disturbances from external parameters like temperature and pH, exhibiting strong environmental flexibility. MIP can specifically adsorb organophosphate esters, and can selectively adsorb TNBP under the interference of coexisting contaminants such as1,3-diphenylguanidine and isazofos. In actual bodies of water, MIP's highly selective adsorption of TNBP retains its advantage. The selective adsorption of MIP was mainly due to the common phosphate skeleton, and the specific substituent of organophosphate esters played an important role in the imprinting process. Hydrogen bonding might be involved in the polymerization process of TNBP with acrylamide and the adsorption process of TNBP by MIP.MIP exhibited good reuse efficiency, the total adsorption capacity decreased by no more than 25% after 7 reuse cycles. This study provides a simple and efficient method for selective removal of organophosphate from wastewater.

Adsorption Performance and Mechanisms of Tetracycline on Clay Minerals in Estuaries and Nearby Coastal Areas

Clay minerals in sediments have strong adsorption capacities for pollutants, but their role in the distribution of antibiotics in estuaries and nearby coastal areas is unclear. We evaluated the clay mineral montmorillonite (SWy-2) adsorption capacity for tetracycline (TC). We assessed the adsorption capacity of SWy-2 for TC by measuring the removal percentage of 30 mg/L TC over time. The effects of pH and ionic strength on the TC adsorption onto SWy-2 were investigated. We analyzed the kinetics of TC adsorption using a pseudo-second-order model and determined the adsorption isotherm using the Langmuir equation. SWy-2 particles were characterized using zeta potential, Fourier transform infrared (FTIR), and X-ray diffraction (XRD) analyses before and after TC adsorption. The removal percentage of 30 mg/L TC by SWy-2 reached 70.76% within 0.25 h and gradually increased to 78.64% at 6 h. TC adsorption was influenced by pH and ionic strength, where low pH enhanced and high ionic strength reduced the adsorption. The kinetics of TC adsorption followed a pseudo-second-order model, and the adsorption isotherm adhered to the Langmuir equation. The saturated adsorption capacity (qmax) of SWy-2 for TC was 227.27 mg/g. Zeta potential, FTIR, and XRD analyses confirmed that electrostatic interactions and chemical bonds played a significant role in the TC adsorption by SWy-2. SWy-2 clay mineral exhibits a substantial adsorption capacity for TC, indicating its potential as an effective sorbent to mitigate antibiotic contamination in estuaries and nearby coastal areas. The observed effects of pH and ionic strength on TC adsorption have implications for the environmental fate and transport of antibiotics. The pseudo-second-order kinetic model and Langmuir isotherm equation provide valuable insights into the adsorption behavior and capacity of TC on SWy-2. Characterization analyses support the involvement of electrostatic interactions and chemical bonds in the SWy-2-TC adsorption mechanism.

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

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

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.

Multimedia fate of sulfamethoxazole (SMX) in a water-scarce city by coupling fugacity model and HYDRUS-1D model

Increased concentrations of pharmaceutical and personal care products (PPCPs) have raised concerns about their impact on the ecological system and human health. To understand the environmental impact of PPCPs, we evaluated the fate of a typical PPCP of sulfamethoxazole (SMX) in a water-scarce city of Tianjin during 2013-2020 using a coupled model based on the dynamic fugacity model and HYDRUS-1D model. The results showed that the coupled model successfully simulated the reported SMX concentrations in the main fate media of water and soils, which accounted for 46.4 % and 53.0 % with equilibrium concentrations of 135-165 ng/L and 0.4-0.5 ng/g, respectively. The cross-media transfer flux results showed that advection was the prime input path for SMX in water, while degradation was the dominant output path. Wastewater irrigation and degradation were the main transfer processes of SMX in the soil. Moreover, human activities (i.e., emission loads) and climate (i.e., temperature and precipitation) change can significantly affect the concentrations and transfer rate of SMX in the media. These findings provide basic data and methods for the risk assessment of SMX in water-scarce regions.

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.

Occurrence, source apportionment and ecological risk assessment of thirty antibiotics in farmland system

Antibiotics are widely used in medical care, livestock production, and aquaculture. However, antibiotic pollution has attracted increasing global concerns due to their ecological risks after entering into environmental ecosystem via animal excretion, effulent from industrial and domestic sewage treatment facilities. In this study, 30 antibiotics were investigated in soils and irrigation rivers using ultra-performance liquid chromatography-triple quadrupole tandem mass spectrometer. This study evaluated the occurrence, source apportionment, and ecological risks of these target compounds in soils and irrigation rivers (i.e., sediments and water) of farmland system by using principal component analysis-multivariate linear regression (PCA-MLR) and risk quotients (RQ). The concentration range of antibiotics in soils, sediments, and water was 0.38-689.58 ng/g, 81.99-658.00 ng/g, and 134.45-1547.06 ng/L, respectively. In soils, the most abundant antibiotics were quinolones and antifungals with an average concentration of 30.00 ng/g and 7.69 ng/g, respectively, contributing to 40% of total antibiotics. Macrolides were the most frequently detected antibiotics in soils with an average concentration of 4.94 ng/g. In irrigation rivers, quinolones and tetracyclines, the most abundant antibiotics, accounted for 78% and 65% of antibiotics in water and sediments, respectively. Higher antibiotic contamination of irrigation water was primarily distributed in highly populated urban areas, while increasing antibiotic contamination of sediments and soils was particularly observed in rural areas. PCA-MLR analysis indicated that antibiotic contamination in soils was mainly ascribed to the irrigation of sewage-receiving water body and manure application of livestock and poultry farming, which cumulatively contributed to 76% of antibiotics. According to RQ assessment, quinolones in irrigation rivers posed high risk to algae and daphnia, contributing 85% and 72% to the mixture risk, respectively. In soils, macrolides, quinolones and sulfonamides were responsible for more than 90% to the mixture risk of antibiotics. Ultimately, these findings can improve our fundamental knowledge on contamination characteristics and source pathways towards risk management of antibiotics in farmland system.

Occurrence and Distribution of Antibiotics in a Tropical Mariculture Area of Hainan, China: Implications for Risk Assessment and Management

With the rapid global demand for mariculture products in recent years, the use of antibiotics has increased intensively in the mariculture area. Current research on antibiotic residues in mariculture environments is limited, and less information is available on the presence of antibiotics in tropical waters, limiting a comprehensive understanding of their environmental presence and risk. Therefore, this study investigated the environmental occurrence and distribution of 50 antibiotics in the near-shore aquaculture waters of Fengjia Bay. A total of 21 antibiotics were detected in 12 sampling sites, including 11 quinolones, 5 sulfonamides, 4 tetracyclines, and 1 chloramphenicol; the quinolones pyrimethamine (PIP), delafloxacin (DAN), flurofloxacin (FLE), ciprofloxacin (CIP), norfloxacin (NOR), pefloxacin (PEF), enrofloxacin (ENO), and minocycline (MNO) of the tetracycline class were detected in all sampling points. The total antibiotic residue concentrations in the study area ranged from 153.6 to 1550.8 ng/L, the tetracycline antibiotics were detected in the range of 10 to 1344.7 ng/L, and the chloramphenicol antibiotics were detected in the range of 0 to 106.9 ng/L. The detected concentrations of quinolones ranged from 81.3 to 136.1 ng/L, and the residual concentrations of sulfonamide antibiotics ranged from 0 to 313.7 ng/L. The correlation analysis with environmental factors revealed that pH, temperature, conductivity, salinity, NH^3--N, and total phosphorus had a strong correlation with antibiotics. Based on PCA analysis, the main sources of antibiotic pollution in the area were determined to be the discharge of farming wastewater and domestic sewage. The ecological risk assessment indicated that the residual antibiotics in the water environment of the near-shore waters of Fengjiawan had certain risks to the ecosystem. Among them, CIP, NOR, sulfamethoxazole (TMP), ofloxacin (OFL), enrofloxacin (ENO), sulfamethoxazole (SMX), and FLE showed medium to high risk. Therefore, it is recommended to regulate the use of these antibiotics and the discharge and treatment of culturing wastewater, and measures should be taken to reduce the environmental pollution caused by antibiotics and to monitor the long-term ecological risk of antibiotics in the region. Overall, our results provide an important reference for understanding the distribution and ecological risk of antibiotics in Fengjiawan.

Modified UiO-66-Br Microphotocatalyst with High Electron Mobility Enhances Tetracycline Degradation

In this work, the Br functional group on the ligand UiO-66-Br was modified with a Bi-O bond through the secondary solvothermal method, and the synthesis method of visible light catalyst UB (UiO-66-BiOBr) with high electron mobility was explored. The findings indicate that the effective charge transfer of the functional group-modified material UB is 2.98 times and 1.22 times that of BiOBr and traditional UiO-66/BiOBr heterojunctions, respectively. Under simulated sunlight irradiation, the removal rate of tetracycline can reach 88.71%, and the photocatalytic performance is 22.73 times higher than that of UiO-66-Br. Moreover, it maintains good adsorption and photocatalytic performance under different laboratory and actual engineering water environment conditions. In the complex water environment of municipal wastewater, the degradation effect reaches more than 80%. Finally, the decomposition pathways of TC and ecotoxicities of the intermediates were analyzed via combining theoretical calculation, LC-MS/MS, and T.E.S.T.

Estimating Sources, Fluxes, and Ecological Risks of Antibiotics in the Wuhan Section of the Yangtze River, China: A Year-Long Investigation

To our knowledge, ours is the first study to investigate the annual fluxes, environmental fate, and ecological risks of five categories of antibiotics from the Wuhan section of the Yangtze River (China). All the 24 antibiotics we tested for were detected in water, with total concentrations of 17.11-867.2 ng/L (mean: 63.69 ng/L), and 19 antibiotics were detected in sediment, at 0.02-287.7 ng/g (mean: 16.54 ng/g). Sulfonamides, amphenicols, and macrolides were the three most prominent antibiotic classes in water, and fluoroquinolones were the most prominent in sediment. Farming activities (animal husbandry and aquaculture) are proposed as the largest contributors to antibiotic pollution in the Wuhan section of the Yangtze River according to the Unmix model, followed by municipal wastewater and mixed sources. Higher pollution levels were observed downstream (combined discharge of these sources). Monthly monitoring data (12 months) were used to estimate antibiotic annual fluxes, with 101.5 t (uncertainty: 5.6%) in the Wuhan section of the Yangtze River. Risk assessments showed that erythromycin, clarithromycin, and azithromycin posed medium and high ecological risks and were found in 9%-35% and 1.8%-3.7% of all water samples, respectively; enrofloxacin, clarithromycin, azithromycin, florfenicol, and thiamphenicol posed medium resistance risks in 1.9%-16.7% of waters in the Wuhan section of the Yangtze River. Our results have filled data gaps on antibiotic sources, annual fluxes, and resistance risk in the Wuhan section of the Yangtze River and demonstrated the importance of further management of antibiotic use in the studied areas. Environ Toxicol Chem 2023;42:605-619. © 2022 SETAC.

Seasonal variation and ecological risk assessment of Pharmaceuticals and Personal Care Products (PPCPs) in a typical semi-enclosed bay - The Bohai Bay in northern China

The Bohai Bay as a typical semi-enclosed bay in northern China with poor water exchange capacity and significant coastal urbanization, is greatly influenced by land-based inputs and human activities. As a class of pseudo-persistent organic pollutants, the spatial and temporal distribution of Pharmaceuticals and Personal Care Products (PPCPs) is particularly important to the ecological environment, and it will be imperfect to assess the ecological risk of PPCPs for the lack of systematic investigation of their distribution in different season. 14 typical PPCPs were selected to analyze the spatial and temporal distribution in the Bohai Bay by combining online solid-phase extraction (SPE) and HPLC-MS/MS techniques in this study, and their ecological risks to aquatic organisms were assessed by risk quotients (RQs) and concentration addition (CA) model. It was found that PPCPs widely presented in the Bohai Bay with significant differences of spatial and seasonal distribution. The concentrations of ∑PPCPs were higher in autumn than in summer. The distribution of individual pollutants also showed significant seasonal differences. The high values were mainly distributed in estuaries and near-shore outfalls. Mariculture activities in the northern part of the Bohai Bay made a greater contribution to the input of PPCPs. Caffeine, florfenicol, enrofloxacin and norfloxacin were the main pollutants in the Bohai Bay, with detection frequencies exceeding 80 %. The ecological risk of PPCPs to algae was significantly higher than that to invertebrates and fish. CA model indicated that the potential mixture risk of total PPCPs was not negligible, with 34 % and 88 % of stations having mixture risk in summer and autumn, respectively. The temporary stagnation of productive life caused by Covid-19 weakened the input of PPCPs to the Bohai Bay, reducing the cumulative effects of the pollutants. This study was the first full-coverage investigation of PPCPs in the Bohai Bay for different seasons, providing an important basis for the ecological risk assessment and pollution prevention of PPCPs in the bay.

Bisphenol analogues in water and sediment from the Beibu Gulf, South China Sea: Occurrence, partitioning and risk assessment

Bisphenol analogues (BPs) have gained increasing attention in recent years due to their ubiquitousness in the environment, potential endocrine disrupting properties and ecological impacts. However, very little information is available on the occurrence, partitioning and ecological risks of BPs in marine environments. In the present study, six BPs were investigated in surface water and sediment samples from the Beibu Gulf, South China Sea. Results showed that bisphenol A (BPA) was the predominant BP in both water and sediment samples with levels ranging from 5.26 to 12.04 ng/L in water and 0.56 to 5.22 ng/g dw in sediment samples, followed by bisphenol AF (BPAF: 0.44-0.60 ng/L in water and 0.08-0.66 ng/g dw in sediment samples, respectively) and bisphenol S (BPS: 0.07-0.63 ng/L in water and not detected (ND) to 0.19 ng/g dw in sediment samples, respectively). There is no significant spatial difference of BPs levels between riverine sediment samples and coastal sediment samples. Compared with other studies, the concentrations of BPs from the Beibu Gulf were relatively low. The mean log-transformed sediment-seawater partitioning coefficients (log K_oc) ranged from 4.4 (DHBP) to 5.2 (BPAF) and the log K_oc values for all the target BPs were generally higher than those reported in freshwater environments. The present study firstly reported the field-based log K_oc values for BPB (mean: 4.5) and DHBP (mean: 4.4). The estimated risk quotient (RQ) and 17β-estradiol (E2) equivalent quotient (EEQ) values indicated that the ecological and human health impacts were negligible associated with target BPs. The present study provided reliable and detailed data for completely evaluating contamination level and environmental behaviors of BPs in the Beibu Gulf.

Ecological and human health risks of antibiotics in marine species through mass transfer from sea to land in a coastal area: A case study in Qinzhou Bay, the South China sea

Antibiotics have been detected in aquatic environment around the world. Understanding internal concentrations of antibiotics in organisms could further improve risk governance. In this study, we investigated the occurrence of seven sulfonamides, four tetracyclines, five fluoroquinolones, and five macrolides antibiotics in six fish, four crustaceans, and five mollusks species collected from Qinzhou Bay, an important part of the Beibu Gulf in the South China Sea in 2018. 19 of all the 21 target antibiotics were detectable in biota. The total concentrations of the antibiotics ranged from 15.2 to 182 ng/g dry weight in all marine organisms, with sulfonamides and macrolides being the most abundant antibiotics. Mollusks accumulated more antibiotics than fish and crustaceans, implying the species-specific bioaccumulation of antibiotics. The pH dependent partition coefficients of antibiotics exhibited significantly positive correlation with their concentrations in organisms. The ecological risk assessment suggested that marine species in Qinzhou Bay were threatened by azithromycin and norfloxacin. The annual mass loading of antibiotics from Qinzhou Bay to the coastal land area for human ingestion via marine fishery catches was 4.02 kg, with mollusks being the predominant migration contributor. The estimated daily intakes of erythromycin indicated that consumption of seafood from Qinzhou Bay posed considerable risks to children (2-5 years old). The results in this study provide important insights for antibiotics pollution assessment and risk management.

Seasonal occurrence of multiple classes of antibiotics in East China rivers and their association with suspended particulate matter

Understanding the occurrence and fate of antibiotics from different categories is vital to predict their environmental exposure and risks. This study presents the spatiotemporal occurrence of 45 multi-class antibiotics and their associations with suspended particulate matter (SPM) in Xiaoqing River (XRB) and Yellow River (YRB) via 10-month monitoring in East China. Thirty-five and 31 antibiotics were detected in XRB and YRB, respectively. Among them, fluoroquinolones (FQs) had the highest total mean concentration (up to 24.8 μg/L in XRB and 15.4 μg/L in YRB), followed by sulfonamides (SAs) (14.0 μg/L and 15.4 μg/L) and macrolides (MLs) (1.1 μg/L and 1.6 μg/L). Significant spatial-temporal variations were found in both rivers where higher concentrations of antibiotics were observed in urban and densely populated areas during winter and spring. Hydrological factors such as river flow and water volume, instream attenuation and antibiotic usage may cause the observed variabilities in the seasonal patterns of antibiotic pollution. Using linear regression analysis, for the first time, this study confirmed that the total concentrations of MLs (p < 0.05), FQs (p < 0.001) and SAs (p < 0.001) were strongly correlated with the turbidity/total suspended solids in the studied rivers (except MLs in YRB). It is thus suggested that partitioning processes onto SPM might affect the distribution of detected antibiotics in rivers, which are largely dependent on SPM composition and characteristics. The risk quotient (RQ) determined for up to 87 % of individual compound was below 0.1 in both rivers; however, the high joint toxicity reflected by the mixed RQs of detected antibiotics may rise risk alarm for aquatic species. Further aspects regarding active mechanisms of SPM-antibiotic interactions and ecological risks of coexistence of multiple antibiotics need to be investigated.

Antibiotics in the Basque coast (N Spain): Occurrence in waste and receiving waters, and risk assessment (2017-2020)

The study of the presence of antibiotics in the aquatic environment is a preliminary step to analyse their possible harmful effects on aquatic ecosystems. In order to monitor their occurrence in the aquatic environment, the European Commission established in 2015, 2018, and 2020 three Watch Lists of substances for Union-wide monitoring (Decisions (EU) 2015/495, 2018/840, and 2020/1161), where some antibiotics within the classes of macrolides, fluoroquinolones and penicillins were included. In the Basque coast, northern Spain, three macrolide antibiotics (erythromycin, clarithromycin, azithromycin) and ciprofloxacin were monitored quarterly from 2017 to 2020 (covering a period before and after the COVID19 outbreak), in water samples collected from two Waste Water Treatment Plants (WWTPs), and three control points associated with receiving waters (transitional and coastal water bodies). This work was undertaken for the Basque Water Agency (URA). The three macrolide antibiotics in water showed a frequency of quantification >65 % in the Basque coast, with higher concentrations in the WWTP emission stations than in receiving waters. Their frequency of quantification decreased from 2017 to 2020, as did the consumption of antibiotics in Spanish primary care since 2015. Ciprofloxacin showed higher frequencies of quantification in receiving waters than in wastewaters, but the highest concentrations were observed in the WWTP emission stations. Although consumption of fluoroquinolones (among which is ciprofloxacin) in primary care in the Basque Country has decreased in recent years, this trend was not observed in the waters sampled in the present study. On the other hand, concentrations of clarithromycin, azithromycin, and ciprofloxacin in receiving waters exceeded their respective Predicted No-Effect Concentrations, so they could pose an environmental risk. These substances are widely used in human and animal medicine, so, although only ciprofloxacin is included in the third Watch List, it would be advisable to continue monitoring macrolides in the Basque coast as well.

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.