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As a class of common emerging pollutants, per- and polyfluoroalkyl substances (PFASs) and their alternatives have been widely detected in various environmental matrices, exhibiting a great threat to the ecological environment and human health. Nevertheless, changes in biomolecular structure and function of duckweed caused by PFASs and their alternatives remain unknown thus far. Herein, the effects of four PFASs, including two common legacy PFASs (perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA)) and two PFASs alternatives (perfluorobutane sulfonic acid (PFBS) and 1H,1H,2H, 2H-perfluorooctane sulfonic acid (6:2 FTS)) on duckweed (Lemna minor) at biochemical level were investigated with Fourier transform infrared spectroscopy (FTIR). Although no obvious inhibitions were observed in the growth of L. minor with PFASs exposure at three levels of 1 μg L

Brain is a potential target for neuroprogestogens and/or peripheral progestogens. Previous studies reported that expression of genes about steroidogenesis, reproduction, cell cycle, and circadian rhythm in zebrafish brain could be affected by progestogens. However, there are limited information from metabolites or biomacromolecules aspects, leaving an enormous gap in understanding toxic effects of progestogens on fish brain. In this study, we exposed zebrafish embryos to 2.8, 27.6, and 289.8 ng/L dydrogesterone (DDG, a synthetic progestogen) until sexual maturity (140 days). LC-MS and GC-MS based untargeted metabolomics and Fourier-transform infrared (FTIR) spectroscopy were then performed to investigate the metabolic profiles and macromolecular changes of brain of these zebrafish. The results from multivariate statistical analysis of metabolite features showed a clear separation between different treatment groups of both female and male zebrafish brains. DDG exposure increased the levels of cholesterol, saturated fatty acids, and nucleoside monophosphates, but decreased the contents of polyunsaturated fatty acids (PUFAs), lysophosphatides, and nucleosides in dose-dependent manner. FTIR results indicated that DDG exposure led to accumulation of saturated lipids, reduction of nucleic acids and carbohydrates, and alteration of protein secondary structures. The findings from this study demonstrated that DDG could affect contents of metabolites and biomacromolecules of zebrafish brain, which may finally lead to brain dysfunctions.

The biotransformation of sulfamonomethoxine (SMM) was studied in an aerobic granular sludge (AGS) system to understand the role of sorption by microbial cells and extracellular polymeric substances (EPS) and the role of functional microbe/enzyme biodegradation. Biodegradation played a more important role than adsorption, while microbial cells covered with tightly bound EPS (TB-EPS) showed higher adsorption capacity than microbial cells themselves or microbial cells covered with both loosely bound EPS (LB-EPS) and TB-EPS. The binding tests between EPS and SMM and the spectroscopic analyses (3D-EEM, UV-Vis, and FTIR) were performed to obtain more information about the adsorption process. The data showed that SMM could interact with EPS by combining with aromatic protein compounds, fulvic acid-like substances, protein amide II, and nucleic acids. Batch tests with various substances showed that SMM removal rates were in an order of NH

The presence of benzothiazoles (BTHs) and organic ultraviolet filters (UV filters) in aquatic ecosystems has emerged as a significant environmental issue, requiring urgent and efficient determination methods. A new, rapid, and sensitive determination method using gas chromatography triple quadrupole mass spectrometer (GC-MS/MS) was developed for the simultaneous extraction and analysis of 10 commonly used BTHs and 10 organic UV filters in surface water, wastewater, sediment, and sludge. For aqueous samples, solid-phase extraction (SPE) method was employed with optimizing of SPE cartridge type, pH, and elution solvent. For solid samples, ultrasonic extraction-solid-phase extraction purification (UE-SPE) and pressurized liquid extraction (PLE) methods were compared. And extraction conditions for ultrasonic extraction method (extraction solvents and extraction times) and PLE method (extraction temperatures and extraction cycles) were optimized. The limits of quantification for the 20 target compounds in surface water and wastewater were 0.01-2.12 ng/L and 0.05-6.14 ng/L, while those for sediment and sludge with UE-SPE method were 0.04-5.88 ng/g and 0.22-6.61 ng/g, respectively. Among the 20 target compounds, the recoveries ranged from 70 to 130% were obtained for 16, 15, 15, and 15 analytes in the matrix-spiked samples of surface water, wastewater, sediment, and sludge with three levels, respectively. And the precision was also acceptable with relative standard deviation (RSD) below 20% for all analytes. The developed methods were applied for the determination and quantification of target compounds in surface water, sediment, wastewater, and sludge samples collected from two wastewater treatment plants (WWTPs) and the Pearl River in Guangzhou, China. BTHs were frequently detected in surface water and wastewater, while UV filters were mainly found in sediment and sludge. Benzotriazole (BT) and 2-hydroxybenzothiazole (2-OH-BTH) were the two major BTHs in influent wastewater and surface water, respectively, with concentrations up to 966 and 189 ng/L. As for sediment and sludge, 2-(2'-hydroxy-5'-octylphenyl)-benzotriazole (UV-329) was a predominant chemical, detected at concentrations of 111 and 151 ng/g, respectively.

Perfluoroalkyl substances (PFASs) are persistent chemicals in the environment. So far, little is known about their uptake potential in wetland plants. Here, we investigated the uptake and translocation of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) in eight common wetland plants, namely

Cyclophosphamide, one of the earliest prescribed alkylating anticancer drugs, has been frequently detected in aquatic environments. However, its effects on fish behavior and associated mechanisms remain largely unknown. In this study, the behaviors, neurochemicals, and gut microbiota of adult zebrafish were investigated after 2 months of exposure to CP at 0.05, 0.5, 5, and 50 µg/L. Behavioral assays revealed that CP increased locomotion and anxiety, and decreased the cognition of zebrafish. The alteration of neurotransmitters and related gene expressions in the dopamine and gamma-aminobutyric acid pathways induced by CP may be responsible for the observed changes in locomotion and cognition of adult zebrafish. Meanwhile, CP increased the anxiety of adult zebrafish through the serotonin, acetylcholine, and histamine pathways in the brain. In addition, increased abundances of Fusobacteriales, Reyanellales, Staphylococcales, Rhodobacterals, and Patescibateria in the intestine at the CP-50 treatment were observed. The study has demonstrated that CP affects the locomotion, anxiety, and cognition in zebrafish, which might be linked with the dysfunction of neurochemicals in the brain. This study further suggests that the gut-brain axis might interact to modulate fish behaviors upon exposure to CP (maybe other organic pollutants). Further research is warranted to test this hypothesis.

Synthetic progestins levonorgestrel (LNG) and dydrogesterone (DDG) are frequency detected in surface water. Combined effects of LNG and DDG on gonad differentiation are similar to LNG single exposure in juvenile zebrafish. However, LNG and DDG mixtures have stronger effects on spermatogenesis in testes of adult zebrafish, which show variable at different life stage. Effects of LNG and DDG mixtures on eyes and brain remain unknown. Here we investigated effects of LNG, DDG and their mixtures on eyes and brain. Zebrafish were exposed to LNG, DDG and their mixtures from 2 hpf to 144 dpf. Rhythm and vision related biological processes were enriched in eyes and brain in LNG and DDG treatments, which indicated rhythmic oscillation in eyes and brain. The qPCR data revealed that both LNG and DDG decreased transcription of arntl2 and clocka, while increased transcription of per1a, per1b, rpe65a and tefa in eyes and brain. However, DDG and LNG mixtures had slight effect on transcription of genes related to rhythm and vision. In addition, LNG and DDG reduced the thickness of inner nuclear layer in the eyes. Bliss independent model revealed that LNG and DDG had antagonist effects on transcription and histology in eyes and brain. Moreover, LNG and DDG formed the same hydrogen bonds with green-sensitive opsin-4 and rhodopsin kinase GRK7a. Taken together, LNG and DDG competed with each other for the same binding residues resulting in antagonist effect in their mixtures treatments, and have significant ecological implications to assess combined effects of progestins mixtures on fish in different organs.

Landfill sites have been regarded as a significant source of chemicals of emerging concern (CECs) in groundwater. However, our understanding about the compositions of CECs in landfill leachate and adjacent groundwater is still very limited. Here we investigated the CECs in landfill leachates and groundwater of Guangzhou in South China by target, suspect and non-target analysis using high-resolution mass spectrometry (HRMS). A variety of CECs (n = 242), including pharmaceuticals (n = 64), pharmaceutical intermediates (n = 18), personal care products (n = 9), food additives (n = 18), industrial chemicals (n = 82, e.g., flame retardants, plasticizers, antioxidants and catalysts), pesticides (n = 26), transformation products (n = 8) and other organic compounds (n = 17) were (tentatively) identified by non-target and suspect screening. 142 CECs were quantitated with target analysis, and among them 37, 24 and 27 CECs were detected respectively in the raw leachate (272-1780 μg/L), treated leachate (0.25-0.81 μg/L) and groundwater (0.10-53.7 μg/L). The CECs in the raw leachates were efficiently removed with the removal efficiencies greater than 88.7%. Acesulfame, bisphenol F and ketoprofen were the most abundant compounds in both treated leachate and groundwater. The CECs in groundwater was found most likely to be originated from the landfill sites. Our results highlight the importance of non-target screening in identifying CECs, and reveal the contamination risk of groundwater by landfill leachate.

Microplastics (MPs) are ubiquitous in aquatic environments, which are important carriers of emerging contaminants (ECs). Biofilms can be attached to the surface of MPs in a natural aquatic environment, which may influence chemical adsorption; however, knowledge of its impact is still limited. This study investigated the effect of biofilms on MPs on the adsorption of ECs through field-laboratory exposure experiments. Three types of MPs were naturally colonized with biofilms in lake. Then, biofilm-absent/biofilm-attached MPs were exposed to nine EC solutions at a concentration of 8 μg/L of each compound in laboratory. Most compounds exhibited 3.8 times lower concentrations on biofilm-attached MPs than on biofilm-absent MPs; only a few compounds showed enhanced adsorption. Pseudo-equilibrium was achieved within 72 h based on adsorption kinetics, implying fast adsorption of ECs on biofilm-attached MPs. The partition coefficients (K

Neonicotinoids (NEOs), as the most-consumed pesticides on a global scale, have posed a serious threat to human health and ecological environment. Information regarding the emission history of NEOs is of great importance to improve the prediction of their environmental loading and biological risk potential. In the present study, contamination levels and compositions of 12 NEOs were identified in 8 sediment cores from the Lingdingyang Estuary, which was impacted by agricultural emissions in riverine runoff of the Pearl River Basin for centuries. The total concentration of 12 target NEOs (∑

Increased disinfection efforts in various parts of China, including Hong Kong, to prevent the spread of the novel coronavirus may lead to elevated concentrations of disinfectants in domestic sewage and surface runoff in Hong Kong, generating large quantities of toxic disinfection byproducts. Our study investigated the presence and distribution of four trihalomethanes (THMs), six haloacetic acids (HAAs), and eight nitrosamines (NAMs) in rivers and seawater in Hong Kong. The concentrations of THMs (mean concentration: 1.6 µg/L [seawater], 3.0 µg/L [river water]), HAAs (mean concentration: 1.4 µg/L [seawater], 1.9 µg/L [river water]), and NAMs (mean concentration: 4.4 ng/L [seawater], 5.6 ng/L [river water]) did not significantly differ between river water and seawater. The total disinfection byproduct content in river water in Hong Kong was similar to that in Wuhan and Beijing (People's Republic of China), and the total THM concentration in seawater was significantly higher than that before the COVID-19 pandemic. Among the regulated disinfection byproducts, none of the surface water samples exceeded the maximum index values for THM4 (80 μg/L), HAA5 (60 μg/L), and nitrosodimethylamine (100 ng/L) in drinking water. Among the disinfection byproducts detected, bromoform in rivers and seawater poses the highest risk to aquatic organisms, which warrants attention and mitigation efforts. Environ Toxicol Chem 2022;41:2613-2621. © 2022 SETAC., The present study was financially supported by the General Research Fund of Hong Kong (grant. 18300919), FLASS Dean's Research Fund (grant 04615), and Internal Research Fund (grant R4175) of The Education University of Hong Kong.

Bisphenol A (BPA), 4-nonylphenol (4-NP), and triclosan (TCS) are phenolic endocrine disrupting chemicals (EDCs), which are widely detected in aquatic environments and further bioaccumulated and metabolized in fish. Physiologically based toxicokinetic (PBTK) models have been used to describe the absorption, distribution, metabolism, and excretion (ADME) of parent compounds in fish, whereas the metabolites are less explored. In this study, a PBTK incorporating metabolism (PBTK-MT) model for BPA, 4-NP, and TCS was established to enhance the performance of the traditional PBTK model. The PBTK-MT model comprised 16 compartments, showing great accuracy in predicting the internal concentrations of three compounds and their glucuronidated and sulfated conjugates in fish. The impact of typical hepatic metabolism on the PBTK-MT model was successfully resolved by optimizing the mechanism for deriving the partition coefficients between the blood and liver. The PBTK-MT model exhibited a potential data gap-filling capacity for unknown parameters through a backward extrapolation approach of parameters. Model sensitivity analysis suggested that only five parameters were sensitive in at least two PBTK-MT models, while most parameters were insensitive. The PBTK-MT model will contribute to a well understanding of the environmental behavior and risks of pollutants in aquatic biota.

Long-term and extensive usage of thiamethoxam, the second-generation neonicotinoid insecticide, has caused a serious threat to non-target organisms and ecological security. Efficient immobilized microorganism techniques are a sustainable solution for bioremediation of thiamethoxam contamination. A Gram-negative aerobic bacterium Chryseobacterium sp H5 with high thiamethoxam-degrading efficiencies was isolated from activated sludge. Then we developed a novel polyvinyl alcohol (PVA)/sodium alginate (SA)/biochar bead with this functional microbe immobilization to enhance the biodegradation and removal of thiamethoxam. Results indicated that the total removal and biodegradation rate of thiamethoxam with PVA/SA/biochar (0.7 %) beads with Chryseobacterium sp H5 immobilization at 30 °C and pH of 7.0 within 7 d reached about 90.47 % and 68.03 %, respectively, much higher than that using PVA/SA immobilized microbes (75.06 %, 56.05 %) and free microbes (61.72 %). Moreover, the PVA/SA/biochar (0.7 %) immobilized microbes showed increased tolerance to extreme conditions. Biodegradation metabolites of thiamethoxam were identified and two intermediates were first reported. Based on the identified biodegradation intermediates, cleavage of C-N between the 2-chlorothiazole ring and oxadiazine, dichlorination, nitrate reduction and condensation reaction would be the major biodegradation routes of thiamethoxam. Results of this work suggested the novel PVA/SA/biochar beads with Chryseobacterium sp H5 immobilization would be helpful for the effective bioremediation of thiamethoxam contamination.

Hydrophilic organic pollutants (HLOPs) in effluents of wastewater treatment plants are more prevalent than hydrophobic counterparts, therefore development of upstream processes that can effectively enhance the removal of HLOPs can substantially enhance overall treatment performance. To bridge this gap, 3D electrodes made of biochar-supported Al-ZnO nanoparticles (NAZO@BC) applied in heterogeneous electro-Fenton (EF) system, abbreviated as NBE-EF system, is rationally designed for enhanced elimination of HLOPs in wastewater. Our analysis indicates the NBE-EF system results in an efficient THM elimination, 42.4 times greater than that of conventional EF system. MoS

Imidacloprid (IMI) and thiamethoxam (THM) are two commonly applied neonicotinoid insecticides. IMI and THM could cause negative impacts on non-target organisms like bees. However, the information about neurotoxicity of IMI and THM in fish is still scarce. Here we investigated the effects of IMI and THM on locomotor behavior, AChE activity, and transcription of genes related to synaptic transmission in zebrafish exposed to IMI and THM with concentrations of 50 ng L−1 to 50,000 ng L−1 at 14 day post fertilization (dpf), 21 dpf, 28 dpf and 35 dpf. Our results showed that IMI and THM significantly influenced the locomotor activity in larvae at 28 dpf and 35 dpf. THM elevated AChE activity at 28 dpf. The qPCR data revealed that IMI and THM affected the transcription of marker genes belonging to the synapse from 14 dpf to 35 dpf. Furthermore, IMI and THM mainly affected transcription of key genes in γ-aminobutyric acid, dopamine and serotonin pathways in larvae at 28 dpf and 35 dpf. These results demonstrated the neurotoxicity of IMI and THM in zebrafish. The findings from this study suggested that IMI and THM in the aquatic environment may pose potential risks to fish fitness and survival.

Perfluoroalkyl substances (PFASs) have been widely studied by researchers due to their environmental persistence, chemical stability and potential toxicity. Some researchers have reported the physiological and biochemical toxicity of PFASs on plants through traditional and innovative methods; however, the changes in biological macromolecules caused by PFASs are rarely studied. Here, Fourier transform infrared spectroscopy (FTIR) was used to study how exposure to perfluorooctanoic acid (PFOA) alters the structure and function of biomolecules of the wetland plant Alisma orientale. Biomass results showed that PFOA had negative effects on plant growth. FTIR results showed that PFOA could result in changes in the structures, compositions, and functions of lipids, proteins and DNA in plant cells. In the treatment groups, the ratios of CH

The content of active components in magnetic biochar, especially Fe(II), is closely related to its activation performance. Therefore, improving Fe(II) content in magnetic biochar is an ideal strategy to enhance the activation performance of magnetic biochar. In this study, the potassium-doped magnetic biochar was prepared and employed to activate persulfate for degradation of metronidazole. The degradation efficiency of metronidazole in potassium-doped magnetic biochar/persulfate system was 98.4%, which was 13.1 times higher than that in magnetic biochar/persulfate system. Free radicals quenching experiments and electron spin resonance analyses confirmed that surface-bound free radicals were responsible for metronidazole degradation followed the order of 1O2 > OH > SO4− > O2−. The doping of magnetic biochar with potassium increased its Fe(II) content, approximately 3.1 times higher than that of pristine magnetic biochar. The differences in Fe(II) content between potassium-doped magnetic biochar and magnetic biochar were the key reasons for the activation performance differences. Based on the ultra-high pressure liquid chromatography-quadrupole tandem time-of-flight mass spectrometer, the primary degradation intermediates of metronidazole were identified, and possible degrading pathways were proposed. Overall, this work provides an effective strategy to improve the activation performance of magnetic biochar.

Antibiotic residues and antibiotic resistance have been widely reported in aquatic environments. Hydrolysis of antibiotics is one of the important environmental processes. Here we investigated the hydrolytic transformation of four tetracycline antibiotics i.e. tetracycline (TC), chlortetracycline (CTC), oxytetracycline (OTC) and doxycycline (DC) under different environmental conditions, and determined their parents and transformation products in the wastewater treatment plants (WWTPs). The results showed that the hydrolysis of the four tetracyclines followed first-order reaction kinetics, and the acid-catalyzed hydrolysis rates were significantly lower than the base-catalyzed and neutral pH hydrolysis rates. The effect of temperature on tetracycline hydrolysis was quantified by Arrhenius equation, with Ea values ranged from 42.0 kJ mol−1 to 77.0 kJ mol−1 at pH 7.0. In total, nine, six, eight and nine transformation products at three different pH conditions were identified for TC, CTC, OTC and DC, respectively. The main hydrolysis pathways involved the epimerization/isomerization, and dehydration. According to the mass balance analysis, 4-epi-tetracycline and iso-chlortetracycline were the main hydrolytic products for TC and CTC, respectively. The 2 tetracyclines and 4 hydrolysis products were found in the sludge samples in two WWTPs, with concentrations from 15.8 ng/g to 1418 ng/g. Preliminary toxicity evaluation for the tetracyclines and their hydrolysis products showed that some hydrolysis products had higher predicted toxicity than their parent compounds. These results suggest that the hydrolysis products of tetracycline antibiotics should also be included in environmental monitoring and risk assessment.

In this study, chalcopyrite (CuFeS2), a natural mineral with a bimetallic structure, was used as the activator to generate radicals for removing organic pollutants from aqueous solutions via the activation of peroxymonosulfate (PMS). Sulfisoxazole (SIX), a sulfonamide antibiotic, was selected as the model pollutant. The results showed that chalcopyrite was highly reactive toward the activation of PMS; under the conditions of 50 µM PMS and 1 g/L chalcopyrite, approximately 95.7% of the SIX was degraded after reaction for only 5 min. An increase in the loading of chalcopyrite (0.25–2 g/L) promoted the degradation of SIX, while elevated levels of PMS (0.05–0.5 mM) slightly retarded the degradation kinetics. Although the best performance was observed under acidic conditions (pHs 3 and 4), near complete degradation of SIX was also achieved at pH 5.5. Identification of reactive species revealed that both a hydroxyl radical and a sulfate radical were formed in chalcopyrite–PMS oxidation, and they were responsible for the degradation of SIX. Trace amounts of copper and iron were leached out from chalcopyrite during the activation, and both the heterogeneous and homogeneous activation of PMS contributed to the generation of oxidizing radicals. Common water constituents including Cl−, HCO3−, and natural organic matter at their environmentally relevant levels showed a limited effect on the degradation of SIX, which suggests that chalcopyrite–PMS oxidation has high reactivity and stability in the degradation of organic pollutants and shows great practical application potential.

The high use of antibiotics worldwide has poses a serious threat to both human and environmental health. Lakes are served as reservoirs for antibiotics, however, there is a lack of information available on antibiotics emissions and the subsequent pollution. Here, the emission and fate of 34 frequently detected antibiotics were studied in 226 Chinese lakes, via the built emission estimation method and a temperature-dependent multimedia lake model. It has been estimated that totally 5711 tons antibiotic were discharged into the lakes of China in 2019. Antibiotics emissions are due to human activities, with 3800-fold higher emissions in the Eastern China than that in Western China. The antibiotic fate in lakes has been successfully modelled by simulating the lake stratification, freeze-melt cycles and the stable condition throughout the year. Both stratification and freeze-melt cycles can lead to increased antibiotic concentrations in lake water. Deep-water lakes were shown to serve as a highly effective natural storage medium for antibiotics. The reliability of the model was confirmed by published measured concentrations and Monte Carlo method. This is the first study to comprehensively investigate the antibiotic fate in lakes of China, providing valuable guidance for the remediation of contaminated lakes.

Landfills are the main destination of many urban wastes containing per- and polyfluoroalkyl substances (PFAS), and PFAS may leach out from the waste and contaminate the surrounding groundwater. Here we investigated the occurrence of PFAS in leachate and surrounding groundwater from three landfills in Guangzhou, China by using a combined target and non-target approach. Non-target screening showed that a total of 651 PFAS with 96 classes were identified, including 17 legacy PFAS and 637 emerging PFAS. The quantitative target analysis of some PFAS revealed that the average removal rate of PFAS from the raw leachates were ranged between 62 % and 99 %. Statistical analysis and source analysis suggested that landfill leachate was a major source of PFAS in the groundwater within the landfills and downstream sites. The results from the combined target and non-target analyses demonstrated that PFAS in landfills could leach into the surrounding groundwater, and may affect the sustainable use of groundwater as a source of drinking water and pose a potential risk to human health.

Polybrominated dibenzo-p-dioxins/furans (PBDD/Fs) and polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) share similar toxicities and thermal origins, e.g., municipal solid waste incinerator (MSWI). Recently, PBDD/Fs from MSWI attracted rising concern because their important precursors, i.e., brominated flame retardants (BFRs), were frequently found in various wastes for landfill or MSWI feedstock. So far, however, little is known about PBDD/Fs and their associated risks in the vicinal environments of MSWI. Here we analyzed PBDD/Fs and PCDD/Fs in 29 soil samples collected around a multiyear large-scale MSWI, and compared their spatial distributions, sources and risks. PBDD/Fs demonstrated comparable concentrations and toxic equivalent quantities (TEQs) to PCDD/Fs in these samples. Spatially, both the concentrations of PBDD/Fs and PCDD/Fs decreased outwards from the MSWI, and exhibited significant linear correlations with the distances from the MSWI in the southeast downwind soil, suggesting the influence of the MSWI on its vicinal soil environment. However, the existence of other dioxin sources concealed its influence beyond 6 km. PBDD/Fs in the soils were characterized by highly-brominated PBDFs, especially Octa-BDF, and their sources were diagnosed as the MSWI and diesel exhaust; PCDD/Fs, however, were dominated by highly-chlorinated PCDDs, particularly Octa-CDD, and were contributed individually or jointly by the MSWI, automobile exhaust and pentachlorophenol (PCP)/Na-PCP. The non-carcinogenic risks of dioxins in all the soil samples were acceptable, but their carcinogenic risks in 17% of the samples were unacceptable. These samples were all located close to the MSWI and highways, therefore, the land use of these two high-risk zones should be cautiously planed.

Increasing use of feed and medicine in mariculture could cause negative environmental impacts such as habitat modification, microbial disease development and antibiotic resistance. Here we investigated contamination of antibiotics and antibiotic resistance genes (ARGs), and composition of microbial community in grouper mariculture systems in Hainan province, China. Results showed detection of various antibiotic residues with the dominance of fluoroquinolones and tetracyclines in the six grouper cultivation systems. The concentrations of the detected antibiotics in the grouper mariculture water were significantly higher than those in the original seawater. Some of the detected antibiotics such as enrofloxacin, ciprofloxacin, ofloxacin, oxytetracycline and erythromycin in the mariculture water and/or sediment would pose high resistance selection risks. Sulfonamides resistance genes sul1 and sul2 were found to be predominant in water and sediment, while tetracycline resistance genes were prevalent in fish gill and gut. The dominant bacterial phyla in water and sediments were Bacteroides, Actinomycetes, and Proteobacteria, while the dominant ones in fish gill and gut were the Proteobacteria. Genera of Vibrio and Mycobacterium in the core microbiota were important zoonotic pathogens, and there was a significant positive correlation between Vibrio and ARGs. Phyla of Proteobacteria, Actinomyces, and Cyanobacteria were positively correlated to ARGs, indicating that these microorganisms are potential hosts of ARGs. The putative functions of microbiome related to antibiotic resistance and human diseases were significantly higher in fish than in the mariculture environment. This study suggests that mariculture system is a reservoir of ARGs, and the use of antibiotics in mariculture could induce the increase of antibiotic resistance and the prevalence of opportunistic pathogens.

Agricultural plastic films have been proven highly advantageous, but they also cause pollution of plastic debris and associated chemicals. Phthalates (phthalic acid esters, PAEs), an important additive of agricultural films, can be released and contaminate the environment. Here, we analyzed the agricultural plastic usage and assessed plastic debris in China and developed a method to estimate PAE emissions from agricultural films. Additionally, the environmental fate of PAEs was evaluated using a fugacity-based multimedia model. The agricultural plastic film usage in China in 2017 was 2,528,600 tons. After agricultural film recycling and water erosion, the plastic debris amount was estimated as 465,016 tons. The water erosion process carried 4329 tons of plastic debris into the aquatic environment. During its lifetime, the agricultural film released a total of 91.5 tons of two typical types of PAEs. PAEs from the mulching film would mostly be removed through degradation, while those from the greenhouse film accumulate in vegetables. Populated regions exhibited more serious PAE pollution in vegetables but with no immediate health risks. The model was well evaluated using comparable measured concentrations and uncertainty analysis based on the Monte Carlo method. The findings from this study demonstrate the serious agricultural plastic pollution problem and associated PAE contamination in China.

Animal farms have been considered as the critical reservoir of antibiotic resistance genes (ARGs) and antibiotic resistant bacteria (ARB). Spread of antibiotic resistance from animal farms to the surrounding environments via aerosols has become a growing concern. Here we investigated the dispersal pattern and exposure risk of airborne ARGs (especially in zoonotic pathogens) in the environment of chicken and dairy farms. Aerosol, dust and animal feces samples were collected from the livestock houses and surrounding environments (upwind and downwind areas) for assessing ARG profiles. Antibiotic resistance phenotype and genotype of airborne Staphylococcus spp. was especially analyzed to reveal the exposure risk of airborne ARGs. Results showed that airborne ARGs were detected from upwind (50 m/100 m) and downwind (50 m/100 m/150 m) air environment, wherein at least 30% of bacterial taxa dispersed from the animal houses. Moreover, atmospheric dispersion modeling showed that airborne ARGs can disperse from the animal houses to a distance of 10 km along the wind direction. Clinically important pathogens were identified in airborne culturable bacteria. Genus of Staphylococcus, Sphingomonas and Acinetobacter were potential bacterial host of airborne ARGs. Airborne Staphylococcus spp. were isolated from the environment of chicken farm (n = 148) and dairy farm (n = 87). It is notable that all isolates from chicken-related environment were multidrug-resistance (>3 clinical-relevant antibiotics), with more than 80% of them carrying methicillin resistance gene (mecA) and associated ARGs and MGEs. Presence of numerous ARGs and diverse pathogens in dust from animal houses and the downwind residential areas indicated the accumulation of animal feces origin ARGs in bioaerosols. Employees and local residents in the chick farming environment are exposed to chicken originated ARGs and multidrug resistant Staphylococcus spp. via inhalation. This study highlights the potential exposure risks of airborne ARGs and antibiotic resistant pathogens to human health.

Antiviral drugs are among the most common and important classes of pharmaceuticals to treat viral infections, however their continuous emission and persistence in the receiving environment has attracted increasing attention about their potential ecological risks. Here we investigated the occurrence, fate and mass load of 9 antiviral drugs for acquired immunodeficiency syndrome and hepatitis B, in 7 wastewater treatment plants (WWTPs) with different treatment processes in Guangdong, China. Totally, 8 target antiviral drugs were detected in the WWTPs influent wastewater, effluent wastewater and sludge, with maximal concentrations up to 7624 ng/L (telbivudine), 568 ng/L (telbivudine), and 2013 ng/g wet weight (telbivudine), respectively. The removal efficiency varied widely between different antiviral drugs, with the mean aqueous removal efficiency and total removal efficiency ranging from -6.2% (nevirapine) to 100% (lamivudine) and -1.2% (nevirapine) to 100% (lamivudine), respectively. Mass balance analysis showed that their elimination was mostly attributed to the biodegradation/biotransformation. The total back-estimated usage and emission of 9 target antiviral drugs were 77.8 t/y and 13.2 t/y in Guangdong province, China, respectively. Based on the sewage epidemiology approach, the consumption and emission of antiviral drugs in seven studied WWTPs were ranged at 2.31 mg/d/1000 people (nevirapine) to 4970 mg/d/1000 people (telbivudine), and 0 (lamivudine) to 900 mg/d/1000 people (telbivudine), respectively. Preliminary risk assessment showed that the antiviral drugs of zidovudine, ritonavir, lopinavir, and telbivudine in the receiving rivers could pose high ecological risks for aquatic environment. The findings from the present study illustrate the persistence of nevirapine in WWTPs, and provide essential evidence for further study into the development of wastewater treatment technologies.

Antibiotic resistance genes (ARGs) pose a serious threat to environmental biology and public health, along with the discharge and spread of wastewater. The advanced treatment of ARGs in wastewater therefore deserves special attention. In our previous study, we found that tidal flow constructed wetlands can effectively remove multiple ammonia from wastewater. In this study, we further optimized tidal flow constructed wetland systems by adding baffles and cultivating plants; we investigated the influence of process optimization on the removal of ARGs and the influence of functional microorganism distribution on nitrogen removal. The results show that the addition of baffles and plants can effectively improve the removal efficiency of ARGs, with the maximum removal rate of 21 resistance genes, in 7 categories, reaching 83.82%-100.0% with the simultaneous addition of baffles and plants. These removal rates were significantly higher than the increase resulting from a single baffle or plant group. From the comparison of the absolute abundance of ARGs in the substrate and plants, it is clear that the baffles can promote the enrichment of ARGs in the wetland substrate, while uptake by plants is also a way of removing ARGs. Combined with the results of nitrogen-cycle functional gene sequencing, system optimization can increase the diversity and richness of nitrification and denitrification functional microorganisms in the substrate, which is consistent with the higher removal rate of nitrification and total nitrogen in wastewater.

Cyclophosphamide (CP) is a chemotherapy drug which is widely used in the treatment of neoplastic diseases and have often been detected in urban and hospital wastewater, and surface waters. However, at present the effects of CP on aquatic organisms and ecosystems are poorly understood. The main objective of the present study was to assess the effect of CP on the structure and functioning of a sub-tropical freshwater ecosystem (macroinvertebrates, zooplankton and phytoplankton) at environmental relevant concentrations. CP (0, 0.5, 5 and 50 μg/L) was applied weekly to 13,600 L mesocosms over a period of four weeks followed by a one month post exposure period. CP was found to dissipate much faster than previous reported in literature and the half-dissipation times were treatment dependent, being 2.2, 21.3 and 23.6 days in the lowest, middle and highest treatments respectively. Only treatment related effects were observed on the community structure at individual samplings with zooplankton (NOECcommunity = 0.5 μg/L) responding at lower concentrations than phytoplankton (NOECcommunity = 5 μg/L) and macroinvertebrates (NOECcommunity ≥ 50 μg/L). The dissolved organic carbon concentration was consistently higher in the 2 highest treatments, indicating a potential effect on food web interactions and/or the microbial loop. At the population level, consistent adverse effects were observed for the plankton taxa Pleuroxus laevis, Dissotrocha sp. and Oscillatoria sp. at all CP concentrations (NOEC

Biocides are widely added to personal care products and enter the environment through sewage treatment plant (STP) discharge, which affects ecological health. This paper evaluated the pollution characteristics of triclosan and triclocarban in a river network during the COVID-19 epidemic. Moreover, a continuous dynamic river network model coupling a one-dimensional hydrodynamic model and four-level fugacity model was established to address the temporal and spatial heterogeneity of pollutants in the river network migration process; then, this model was applied to evaluate two biocides in the Shima River Basin. The model passed calibration and in-field concentration verification tests and yielded satisfactory simulation results. The results of the study showed that the concentration of biocides in the river network during the new crown epidemic was twice that of the non-epidemic period. The concentration of triclosan and triclocarban in the river channel first increased and then decreased with the increase of the river migration distance after STP discharge. The time variation characteristics of the concentrations were affected by the river flow. The biocide concentration in the river network of the low flow upstream area first increased and then decreased, gradually stabilizing in about 20 h. The pollution concentration in the high flow downstream area was increased, and the concentration did not stabilize at 24 h. These results indicate the necessity of evaluating the temporal and spatial characteristics of migration of typical biocides in the river network by stages and time on the premise of distinguishing the flow.

This study investigated the occurrence and fate of 19 biocides in 8 wastewater treatment plants and receiving aquatic environments (both freshwater and estuarine systems) in Thailand. The predominant compound in wastewater and surface water was methylparaben with the maximum concentration of 15.2 μg/L detected in the receiving river, while in sludge and sediment was triclocarban with the maximum concentration of 8.47 μg/g in sludge. Triclosan was the main contaminants in the fish samples with the maximum concentration of 1.20 μg/g. Similar results of biocides were found in the estuarine system in Pattaya city, with the maximum concentration of 185 ng/L in sea water for methylparaben, and 242 ng/g in estuarine sediment for triclocarban. The aqueous removal rates for the biocides ranged from 15% to 95% in average. The back estimated-usage and total estimated emission of Ʃ19 biocides in Thailand was 279 and 202 tons/year, respectively. Preliminary ecological risk assessment showed that clotrimazole and triclosan could pose high risks to aquatic organisms in the receiving aquatic environments.

Dydrogesterone (DDG) is a synthetic progestin widely used in numerous gynecological diseases. DDG has been shown to disturb fish reproduction, however, the mechanism is still unclear. Here we studied the histological changes and differences of metabolome between exposed and control fish gonads after exposure of zebrafish (Danio rerio) embryos to 2.8, 27.6, and 289.8 ng/L DDG until sexual maturity for a total of 140 days. Dydrogesterone exposure led to male-biased zebrafish sex ratios. Histological examination revealed that DDG induced postovulatory follicles and atretic follicles in the ovary of the female fish. Postovulatory follicles indicated the occurrence of ovulation. DDG also increased spermatids and spermatozoa in the male fish testis, suggesting promotion of spermatogenesis. Ovarian metabolome showed that DDG increased the concentrations of free amino acids, urea, putrescine, free fatty acids, acylcarnitines, lysophospholipids, and other metabolites catabolized from phospholipids. Most of these metabolites are biodegradation products of proteins and lipids, suggesting the existence of ovulated oocytes over-ripening. Further, DDG upregulated arachidonic acid (AA) and its 5‑lipoxygenase (5-LOX) metabolites 5‑oxo‑6,8,11,14‑eicosatetraenoic acid (5-oxo-ETE) in the ovary, which could lead to suppression of AA cyclooxygenase (COX) metabolite prostaglandin F2α (PGF2α). It is believed that AA induced oocyte maturation, while 5-oxo-ETE and related metabolites in purinergic signaling promoted ovulation. Whereas, the suppression of PGF2α production might block spawning and damaged follicular tissue digestion, which explained the oocytes over-ripening and atretic follicles in the treated ovary. Overall, our results suggested that DDG exposure induced zebrafish oocyte maturation and ovulation but led to oocytes over-ripening via the AA metabolic pathway and purinergic signaling. Keywords: Dydrogesterone, Oocyte maturation, Ovulation, Over-ripening, 5-Oxo-ETE, Purinergic signaling

The abundant use of antibiotics leads to antibiotic residues in frequently consumed foods. Residual antibiotics in food may have adverse effects on humans by directly causing disease via low-dose exposure and indirect harm via antibiotic resistance. However, the current methods for antibiotic extraction and analysis in food have not yet formed a uniform standard, and only a few data exist regarding the residual antibiotic condition in various types of foods. Hence, we review the literature since 2008 to summarize analytical methods and residue status of antibiotics in food. Then, we discuss the causes of antibiotic residues in food and the possible hazards to human health. We hope that the joint efforts of the scientific community and political circles will lead to the formation of a unified standard for the extraction and analysis of antibiotics in food, to allow for comprehensive monitoring of residual antibiotics and ensure human health.

Natural and synthetic estrogens and progestins are present in the various aquatic environments, leading to potential exposure of aquatic organisms to their mixtures. However, very little is known about their combined effects in aquatic organisms. The aim of this study was to analyze the effects of binary mixtures of estradiol (E2) and progesterone (P4) by measuring transcriptional changes of up to 42 selected target genes related to hypothalamic-pituitary-gonadal axis and circadian rhythm signaling in zebrafish (Danio rerio) eleuthero-embryos. Zebrafish embryos were exposed to E2 and P4 alone or in combination at concentrations between 45 and 5217 ng L−1 for 96 h post fertilization (hpf). The results showed that P4 led to slight up-regulation of the cyp11a1, hsd17b3 and fshb transcripts, while a strong induction of cyp19a1b and lhb mRNA by E2 was observed. Also, cyp19a1b and lhb mRNAs expression were strongly up-regulated in the mixtures, which were the same to E2 alone. This finding suggests the mixture activity of E2 and P4 followed the independent action in zebrafish eleuthero-embryos. These transcriptional alterations may translate to adverse effects on sex differentiation and reproduction in fish.

Animal manure contains various organic contaminants such as steroids. The fate of these steroids during composting is still unknown. Here we investigated the fate of androgens, progestogens, and glucocorticoids during animal manure composting and evaluated their residues in compost-applied soils. The results showed the presence of 16 steroid hormones in the initial compost with concentrations ranging from 3.26 ng/g dw (Cortisol) to 2520 ng/g dw (5α-dihydroprogesterone). The concentrations of almost all detected hormones increased on the 2nd day of composting, and some of them increased several or even dozens of times. Steroids such as hydroxyprogesterone caproate, melengestrol acetate, and methyltestosterone were not found in the initial compost but later detected during the composting process. After 171 days of composting, only 40.4% of detected steroid hormones was removed, and the total concentration of detected steroids was still as high as 3210 ng/g dw. The removal rates of some target compounds were negative, especially for the natural androgens androsta-1,4-diene-3,17-dione and the synthetic androgen 17β-boldenone whose concentrations significantly increased by the end of composting, indicating conversion from their conjugates or transformation from other steroids. The steroid hormones were mainly eliminated in the first three weeks; prolonged composting time did not obviously promote further removal. The variations in steroid concentration were related to the changes in compost properties such as pH and temperature during the composting process. The dissipation of steroid hormones was also linked to the changes of microbial communities in the compost to some extent. Twelve steroids were detected in the compost-treated soils of a kailyard, while 26 steroid hormones were detected in the roots of Chinese cabbages grown on the soil. The results suggest that the application of manure compost product can lead to soil contamination and plant uptake.

Benzotriazoles (BTs) are a group of heterocyclic compounds which have been widely applied in industrial activities and domestic life mainly as corrosive inhibitors. BTs have been ubiquitously detected in receiving environments and cause potential toxicity to non-target organisms. This paper reviews the occurrence and fate of six selected benzotriazole compounds in different environmental and biological matrices, as well as the transformation and toxicity. Due to their high hydrophilicity and insufficient removal in wastewater treatment plants (WWTPs), these compounds were widely detected in aquatic environments with concentrations mainly from tens ng/L to tens μg/L. Considerable residual levels of BTs in plant, fish, air, tap water and human urine have implied the potential risks to various organsims. The reported acute toxicity of BTs are generally low (EC50 in mg/L level). Some observed sublethal effects including endocrine disrupting effects, hepatotoxicity and neurotoxicity, as well as the ability to promote the development of endometrial carcinoma still raise a concern. BTs are found often more recalcitrant to biodegradation compared to photolysis and ozonation. Environmental factors including pH, temperature, irradiation wavelength, redox condition as well as components of matrix are proved crucial to the removal of BTs. Further studies are needed to explore the precise environment fate and toxicity mechanism of BTs, and develop advanced treatment technologies to reduce the potential ecological risks of BTs.

Occurrence and distribution of five neonicotinoids (NEOs) in surface water and sediment were studied in the Pearl Rivers, including three trunk streams, Dongjiang, Beijiang, Xijiang River (DR, BR and XR), South China. At least one neonicotinoid was detected in surface water and sediment of the Pearl Rivers, with imidacloprid (IMI) and thiamethoxam (THM) being the frequently detected NEOs. Total amount of NEOs (∑5neonics) in surface water and sediment ranged from 24.0 to 322 ng/L, and from 0.11 to 11.6 ng/g dw, respectively. Moreover, the order of contamination level of NEOs in the Pearl Rivers was as follows: XR > DR > BR for surface water, and BR > DR > XR for sediment. Local agricultural activities and effluents of wastewater treatment plants (WWTPs) could be major sources of NEOs in the Pearl Rivers. Solubilization and dilution of NEOs between surface water and sediment during different seasons (spring and summer) could be attributed to rainfall intensities or climate of the Pearl River Delta. An ecological risk assessment of the exposure to current environmental concentration of imidacloprid and ∑5NEOs suggests a threat to sensitive non-target invertebrates, including aquatic invertebrates. Results would provide a better understanding of NEOs contamination in the Pearl Rivers, as well as being a reliable dataset for decision-making in contamination control and environmental protection.

Natural and synthetic steroid hormones have been detected in swine farm wastewaters (SFWs) and receiving waters. However, little is known on their potential endocrine disrupting effects on fish population in receiving rivers. Here we investigated the concentrations of androgens and estrogens in the SFWs and the receiving waters. In addition, the endocrine disrupting effects of SFWs on wild western mosquitofish (Gambusia affinis) were also analyzed by assessing the sex ratio, secondary sex characteristics and transcriptional expression of genes related to the endocrine system. Chemical analysis showed the maximum concentration of total androgens reached 1375.7 ng L−1 in the SFWs and 1020.8 ng L−1 in receiving river waters. A total of 3552 adult G. affinis were collected from the Lianhe River (Guangdong, China), which was heavily impacted by SFWs, before and after the Ban of Swine Farming (BSF) in the river basin. The results showed the presence of male-biased G. affinis populations and masculinized anal fins and hemal spines of females at all contaminated sites prior to BSF. In addition, the transcription of vitellogenin (vtg) was inhibited by SFWs by 99.9% in the females from one sampling site. In contrast, the adverse effects on the females were significantly decreased after BSF. Redundant and path analyses showed that skewed sex ratios of fish populations, masculinized secondary sex characteristics of females and the decrease of vtg transcripts of females were well correlated with the concentrations of androgens in the receiving waters. The findings from this study suggest that SFW can cause masculinization effects of wild G. affinis populations. Keywords: Swine farm wastewater, Hormones, Androgens, Gambusia affinis, Masculinization

An effective analytical method for target and non-target screening of multi-class emerging organic chemicals in aquaculture fish muscle samples using liquid chromatography coupled with high resolution time-of-flight mass spectrometry (LC-QTOF-MS/MS) was reported. Two sample pretreatment methods (QuEChERS and Captiva EMR-Lipid cartridge) were compared and assessed for 151 organic compounds covering a wide range of log Kow (-1.37-11.51) in freeze-dried fish samples. Captiva EMR-Lipid cartridge outperformed QuEChERS by high detection frequency (87.5%) and effective matrix removal with satisfactory standard deviation of the compounds (20%), and meanwhile provided acceptable recoveries for most organic chemicals at three spiking concentration levels (10, 50, and 100 ng g