Exploring the dynamics of antibiotic resistome on plastic debris traveling from the river to the sea along a representative estuary based on field sequential transfer incubations

The environmental risks arising from ubiquitous microplastics or plastic debris (PD) acting as carriers of antibiotic resistance genes (ARGs) have attracted widespread attention. Enormous amounts of plastic waste are transported by rivers and traverse estuaries into the sea every year. However, changes in the antibiotic resistome within the plastisphere (the biofilms formed on PD) as PD travels through estuaries are largely unknown. In this study, we performed sequential migration incubations for PD along Haihe Estuary to simulate the natural process of PD floating from rivers to the ocean. Metagenomic sequencing and analysis techniques were used to track microbial communities and antibiotic resistome on migrating PD and in seawater representing the marine environment. The total relative gene copies of ARGs on traveling PD remained stable. As migration between greatly varied waters, additional ARG subtypes were recruited to the plastisphere. Above 80 % ARG subtypes identified in the plastisphere were persistent throughout the migration, and over 30 % of these persistent ARGs were undetected in seawater. The bacterial hosts composition of ARGs on PD progressively altered as transported downstream. Human pathogenic bacteria carrying ARGs (HPBs-ARG) exhibited decreasing trends in abundance and species number during transfer. Individual HPBs-ARG persisted on transferred PD and were absent in seawater samples, comprising Enterobacter cloacae, Klebsiella pneumoniae, Mycobacterium tuberculosis, and Vibrio parahaemolyticus. Based on all detected ARGs and HPBs-ARG, the Projection Pursuit model was applied to synthetically evaluate the potential risks of antibiotic resistance on migrating PD. Diminished risks on PD were observed upon the river-to-sea journey but consistently remained significantly higher than in seawater. The potential risks posed to marine environments by drifting PD as dispersal vectors for antibiotic resistance deserve greater attention. Our results provide initial insights into the dynamics or stability of antibiotic resistome on PD crossing distinct aquatic systems in field estuaries.

Fish skin mucosal surface becomes a barrier of antibiotic resistance genes under apramycin exposure

Antibiotic resistance genes (ARGs) are a kind of emerging environmental contamination, and are commonly found in antibiotic application situations, attracting wide attention. Fish skin mucosal surface (SMS), as the contact interface between fish and water, is the first line of defense against external pollutant invasion. Antibiotics are widely used in aquaculture, and SMS may be exposed to antibiotics. However, what happens to SMS when antibiotics are applied, and whether ARGs are enriched in SMS are not clear. In this study, Zebrafish (Danio rerio) were exposed to antibiotic and antibiotic resistant bacteria in the laboratory to simulate the aquaculture situation, and the effects of SMS on the spread of ARGs were explored. The results showed that SMS maintained the stability of the bacterial abundance and diversity under apramycin (APR) and bacterial exposure effectively. Until 11 days after stopping APR exposure, the abundance of ARGs in SMS (mean value was 3.32 × 10-3 copies/16S rRNA copies) still did not recover to the initial stage before exposure, which means that enriched ARGs in SMS were persistently remained. Moreover, non-specific immunity played an important role in resisting infection of external contamination. Besides, among antioxidant proteins, superoxide dismutase showed the highest activity. Consequently, it showed that SMS became a barrier of antibiotic resistance genes under APR exposure, and ARGs in SMS were difficult to remove once colonized. This study provided a reference for understanding the transmission, enrichment process, and ecological impact of antibiotics and ARGs in aquatic environments.

Correction: Cyanobacterial extracellular antibacterial substances could promote the spread of antibiotic resistance: impacts and reasons

Correction for 'Cyanobacterial extracellular antibacterial substances could promote the spread of antibiotic resistance: impacts and reasons' by Rui Xin et al., Environ. Sci.: Processes Impacts, 2023, 25, 2139-2147, https://doi.org/10.1039/D3EM00306J.

Pollution characteristics and health risk of sixty-five organics in one drinking water system: PAEs should be prioritized for control

Currently, a large number of emerging organic contaminants have been detected in domestic and international drinking water systems. However, there are differences among the research methods, which lead to system errors in directly comparing the hazards of different contaminants, so it is difficult to analyze the priority control pollutants and the risk control target in drinking water from previous studies. Therefore, we selected a drinking water treatment plant (DWTP) in the east of China, and detected trihalomethanes (THMs), antibiotics, phthalate esters (PAEs), organophosphate esters (OPEs), per and polyfluoroalkyl substances (PFASs), a total of sixty-five organic contaminants in one batch water sample of four seasons, and carried out the whole process monitoring of "Source water-DWTP-Network-Users", and calculated the health risks of contaminants in tap water. The results showed that DWTP could effectively remove antibiotics and PAEs; the removal rate of coagulation for antibiotics can be up to 47%; the release of PAEs in the plastic water supply pipe leads to a significant increase of the concentrations in the water transportation system, which can reach 2.92 times of that in finished water; compared with other contaminants, THMs and PAEs in tap water have higher health risks. This study reveals that THMs and PAEs are priority control organic pollutants, and the water supply network is the key risk control target in the drinking water system, providing a theoretical basis for how to ensure the safety of drinking water.

Exploring the potential of a new marine bacterium associated with plastisphere to metabolize dibutyl phthalate and bis(2-ethylhexyl) phthalate by enrichment cultures combined with multi-omics analysis

Phthalic acid esters (PAEs) plasticizers are virulent endocrine disruptors that are mixed into plastics while fabricating and can filter out once they release into the surrounding environments. Plastic surfaces serve as new habitats for microorganisms, referred to as 'plastisphere'. Previous metagenomic investigations of the 'plastisphere' indicated that marine plastic surfaces may harbor microbes that degrade PAEs plasticizers. To our knowledge, the potential of microorganisms in the marine 'plastisphere' to metabolize PAEs is poorly understood. In this study, by screening the natural microbial community on plastic debris that had been deployed in situ for up to 20 months, a novel marine bacterium, Microbacterium esteraromaticum DEHP-1, was successfully isolated, which could degrade and mineralize 10-200 mg/L dibutyl phthalate (DBP) and bis(2-ethylhexyl) phthalate (DEHP). According to the results of gas chromatography-mass spectrometry (GC-MS) and whole genome mining of strain DEHP-1, we found that strain DEHP-1 may metabolize DBP by successive removal of the ester side chain by esterase 2518 to produce mono-butyl phthalate (MBP) and phthalic acid (PA), whereas the degradation of DEHP may take place by the direct action of monooxygenase 0132 on the fatty acid side chain of the DEHP molecule to produce di-n-hexyl phthalate (DnHP) and DBP, and then the subsequent hydrolysis of DBP by de-esterification to PA and finally into the tricarboxylic acid (TCA) cycle. Non-targeted metabolomics results showed that intracellular degradation of PAEs did not happen. However, exposure to PAEs was found to significantly affect pathways such as arginine and proline, riboflavin, glutathione and lysine degradation. Therefore, the intracellular metabolic behavior of strain DEHP-1 exposed to PAEs was proposed for the first time. This study sheds light on the metabolic capacity and strategies of bacteria in the marine 'plastisphere' to effectively degrade PAEs and highlights the importance of marine microbes in mitigating plastic poisonousness.

Investigation of the antimicrobial susceptibility patterns of marine cyanobacteria in Bohai Bay: Cyanobacteria may be important hosts of antibiotic resistance genes in marine environment

Marine cyanobacteria, as widely distributed and photosynthetically autotrophic bacteria in the ocean, may contribute to the global dissemination of antibiotic resistance genes (ARGs) and develop a different antimicrobial susceptibility pattern from heterotrophic bacteria and cyanobacteria from freshwater environments. However, studies on antimicrobial susceptibility and the carriage of ARGs in marine cyanobacteria are still very limited. In this study, the antibiotic resistance characteristics of cyanobacteria in nearshore waters were examined through field monitoring and laboratory investigations, which included PCR detection and ARG transformation. The results showed a positive correlation between marine cyanobacteria and some ARGs in the nearshore waters of Bohai Bay. Moreover, most screened cyanobacteria showed high minimum inhibitory concentration (MIC) values for polymyxins, tetracyclines, kanamycin, and sulfonamides, moderate MIC values for streptomycin, chloramphenicol, rifampicin, and norfloxacin, and low MIC values for roxithromycin and cephalosporins. The blaTEM, blaKPC, sul1, sul2, strA, tetA, tetB, tetC, tetM, mdfA, and intI1 genes were detected in the screened marine cyanobacteria. The highest detection rates were observed for blaTEM (93.3 %), sul1 (56.6 %), sul2 (90 %), and strA (73.3 %). The detection rate of tetA (33.3 %) was the highest among the tetracycline resistance genes, and mdfA, a multidrug-resistant pump gene with resistance to tetracycline, also showed a high detection level (23.3 %). Overall, most of the screened marine cyanobacteria were found to tolerate multiple antibiotics in seawater, and the condition of the ARGs carriage was serious. Furthermore, the screened marine Synechocystis sp. C12-2 demonstrated the ability to accept ARGs on the RP4 plasmid through natural transformation and showed reduced sensitivity to ampicillin, suggesting the possibility that some marine cyanobacteria could acquire ARGs from the environment through horizontal gene transfer. Thus, marine cyanobacteria may play an important role in the propagation of marine ARGs.

An inversion model of microplastics abundance based on satellite remote sensing: a case study in the Bohai Sea

Nowadays, microplastics (MPs) as emerging contaminants have posed great risks to marine ecosystems and human health. However, non-continuous field sampling data makes it difficult to meet the needs of scientific research and pollution control of marine MPs. Consequently, the development of rapid monitoring techniques for marine MPs to achieve efficient acquisition of data is increasingly essential. Remote sensing technology provides a convenient and effective tool for monitoring and mapping marine MPs pollution. Therefore, we established an inversion model based on multiple regression by combining the remote sensing data and the measured data to predict the MPs pollution status in the Bohai Sea. The feature variables of a model are crucial to the prediction, and we proposed three methods of variable selection, namely successive projections algorithm (SPA), band combination method, and remote sensing index method. By comparing accuracy evaluation metrics, an approach based on SPA was selected to analyze the abundance and spatio-temporal distribution of MPs in the Bohai Sea in 2022. The determination coefficient of the SPA model is 0.75, and the root mean square error is 0.38 items/m3. The error of the model is within an acceptable range. It was found that the MPs abundance on the sea surface of the Bohai Sea varied significantly in different seasons and regions. This study indicates that satellite remote sensing technology has great potential in monitoring marine MPs.

Comparison of chlorination resistance of biodegradable microplastics and conventional microplastics during the disinfection process in water treatments

Nowadays, microplastics (MPs) widely exist in the environment, and water treatment plants are important sources of MPs. Chlorine is widely used in the disinfection process in water treatment plants and has strong oxidation, however, the chemical and physical properties changes of MPs during chlorination were unclear. Thus, in this study, based on the actual used chlorine concentrations, different chlorination conditions were simulated to study the variation of MPs after chlorination. Meanwhile, the produced disinfection by-products were monitored. The results showed that under high chlorination concentration conditions, functional groups of polyethylene (PE), polystyrene (PS), and polylactic acid (PLA) changed, while no peak shift or change of poly (butyleneadipate-co-terephthalate) (PBAT) could be detected. Moreover, after chlorination, partial yellowing and cracks appeared on PS, PLA, and PBAT, while PE remained white and showed little morphological changes. Besides, chlorination led to the narrowing of the cold crystallization peak and melting peak of PLA, while chlorination had little influence on the crystal structure of PE and PBAT. Furthermore, the reaction between PLA and chlorine mostly produced more trichloromethane than other types of MPs. Consequently, when chlorine concentrations were in the range of 2.5 to 5000 mg/L, the chlorination resistance was PBAT/PE > PLA > PS. Specifically, PBAT had the strongest chlorination resistance in terms of chemical properties, while PE had the strongest chlorination resistance in terms of physical properties. Therefore, the degradability of biodegradable MPs is not higher than that of conventional MPs in all cases. Moreover, it should be noted that most changes occurred only in high chlorine concentrations. Thus, neither conventional MPs nor biodegradable MPs can be completely degraded during the chlorination process in water treatments.

Modelling based study on the occurrence characteristics and influencing factors of the typical antibiotics in Bohai Bay

Previous studies have demonstrated that antibiotics have the potential impacts to ecosystems and human health. However, due to their various classes and distinct characteristics, creating comprehensive, integrated and dynamic simulations has proven to be a challenging task. In this study, a 3D hydrodynamic-contaminant model was developed to gain a better understanding of the transportation and prevalence of antibiotics in the Bohai Bay. Specifically, we focused on four types of antibiotics as examples. To accurately capture the dynamic distribution of antibiotics, both transport and biochemical processes were taken into account. Based on this model, the antibiotics' spatial and temporal distribution was examined, the potential impact of the future antibiotics consumption and climate change was also analyzed. The study found that human activity has a greater impact on the presence of antibiotics in Bohai Bay than temperature rise. Based on the current consumption rate, the total amount of antibiotics in Bohai Bay may increase by 10 ng/L and affect nearly one third of the study area within the next 20-30 years. The significant impact of human activity on water contamination in coastal areas may also have implications for other coastal regions. This finding can provide a valuable framework for pollution prevention and control.

Cyanobacterial extracellular antibacterial substances could promote the spread of antibiotic resistance: impacts and reasons

Many studies have shown that antibiotic resistance genes (ARGs) can be facilitated by a variety of antibacterial substances. Cyanobacteria are photosynthetic bacteria that are widely distributed in the ocean. Some extracellular substances produced by marine cyanobacteria have been found to possess antibacterial activity. However, the impact of these extracellular substances on ARGs is unclear. Therefore, we established groups of seawater microcosms that contained different concentrations (1000, 100, 10, 1, 0.1, 0.01, and 0 μg mL-1) of cyanobacterial extracellular substances (CES), and tracked the changes of 17 types of ARGs, the integron gene (intI1), as well as the bacterial community at different time points. The results showed that CES could enrich most ARGs (15/17) in the initial stage, particularly at low concentrations (10 and 100 μg mL-1). The correlation analysis showed a positive correlation between several ARGs and intI1. It is suggested that the abundance of intI1 increased with CES may contribute to the changes of these ARGs, and co-resistance of CES may be the underlying reason for the similar variation pattern of some ARGs. Moreover, the results of qPCR and high-throughput sequencing of 16S rRNA showed that CES had an inhibitory impact on the growth of bacterial communities. High concentrations of CES were found to alter the structure of bacterial communities. Co-occurrence networks showed that bacteria elevated in the high concentration group of CES and might serve as the potential hosts for a variety of ARGs. In general, marine cyanobacteria could play an important role in the global dissemination of ARGs and antibiotic-resistant bacteria (ARBs).

Using CT imaging features to predict visceral pleural invasion of non-small-cell lung cancer

AIM

To examine the diagnostic performance of different models based on computed tomography (CT) imaging features in differentiating the invasiveness of non-small-cell lung cancer (NSCLC) with multiple pleural contact types.

MATERIALS AND METHODS

A total of 1,573 patients with NSCLC (tumour size ≤3 cm) were included retrospectively. The clinical and pathological data and preoperative imaging features of these patients were investigated and their relationships with visceral pleural invasion (VPI) were compared statistically. Multivariate logistic regression was used to eliminate confounding factors and establish different predictive models.

RESULTS

By univariate analysis and multivariable adjustment, surgical history, tumour marker (TM), number of pleural tags, length of solid contact and obstructive inflammation were identified as independent risk predictors of pleural invasiveness (p=0.014, 0.003, <0.001, <0.001, and 0.017, respectively). In the training group, comparison of the diagnostic efficacy between the combined model including these five independent predictors and the image feature model involving the latter three imaging predictors were as follows: sensitivity of 88.9% versus 77% and specificity of 73.5% versus 84.1%, with AUC of 0.868 (95% CI: 0.848-0.886) versus 0.862 (95% CI: 0.842-0.880; p=0.377). In the validation group, the sensitivity and specificity of these two models were as follow: the combined model, 93.5% and 74.3%, the imaging feature model, 77.4% and 81.3%, and their areas under the curve (AUCs) were both 0.884 (95% CI: 0.842-0.919). The best cut-off value of length of solid contact was 7.5 mm (sensitivity 68.9%, specificity 75.5%).

CONCLUSIONS

The image feature model showed great potential in predicting pleural invasiveness, and had comparable diagnostic efficacy compared with the combined model containing clinical data.

Role of traveling microplastics as bacterial carriers based on spatial and temporal dynamics of bacterial communities

Microplastics (MPs) are considered as distinct substrates for bacterial colonization, they can carry bacterial communities to travel around environments. The bacterial communities on traveling MPs prefer to be gradually consistent with those on local MPs that were always in the same environment, and this process of change in the bacterial communities on traveling MPs was called 'localization'. However, the dynamics of localization process and their influencing factors are still unclear. Therefore, we simulated the MPs migration process along the water flow direction in the estuary. We used quantitative analysis to study the dynamics of bacterial communities on the migrated MPs. We found the localization characteristics depended on the differences between the former and latter environments, as well as the preexisting bacteria. The localization degree was higher when the former and latter environments were similar. In most cases, compared with the first cultivation of pristine MPs, the time for localization was shorter. Moreover, although the entire bacterial communities tended to be localized, the preexisting bacteria on the migrated MPs had selective effects on subsequent bacterial colonization. Furthermore, the preexisting bacteria on MPs could set up the connections with the bacteria that existed at the latter site, and the stability of the entire bacterial communities on the migrated MPs increased with time. Overall, our findings indicated that the localization characteristics of bacterial communities on traveling MPs were related to the precultured time and environmental differences, which were helpful to understand the colonized bacteria transportation and MPs ecological effects.

A novel marine bacterium Exiguobacterium marinum a-1 isolated from in situ plastisphere for degradation of additive-free polypropylene

As the ecological niche most closely associated with polymers, microorganisms in the 'plastisphere' have great potential for plastics degradation. Microorganisms isolated from the 'plastisphere' could colonize and degrade commercial plastics containing different additives, but the observed weight loss and surface changes were most likely caused by releasing the additives rather than actual degradation of the plastics itself. Unlike commercial plastics that contain additives, whether marine microorganisms in the 'plastisphere' have adapted to additive-free plastics as a surface to colonize and potentially degrade is not yet known. Herein, a novel marine bacterium, Exiguobacterium marinum a-1, was successfully isolated from mature 'plastisphere' that had been deployed in situ for up to 20 months. Strain a-1 could use additive-free polypropylene (PP) films as its primary energy and carbon source. After strain a-1 was incubated with additive-free PP films for 80 days, the weight of films decreased by 9.2%. The ability of strain a-1 to rapidly form biofilms and effectively colonize the surface of additive-free PP films was confirmed by Scanning Electron Microscopy (SEM), as reflected by the increase in roughness and visible craters on the surface of additive-free PP films. Additionally, the functional groups of -CO, -C-H, and -OH were identified on the treated additive-free PP films according to Fourier Transform Infrared (FTIR). Genomic data from strain a-1 revealed a suite of key genes involved in biosurfactant synthesis, flagellar assembly, and cellular chemotaxis, contributing to its rapid biofilm formation on hydrophobic polymer surfaces. In particular, key enzymes that may be responsible for the degradation of additive-free PP films, such as glutathione peroxidase, cytochrome p450 and esterase were also recognized. This study highlights the potential of microorganisms present in the 'plastisphere' to metabolize plastic polymers and points to the intrinsic importance of the new strain a-1 in the mitigation of plastic pollution.

Biofilms retard the desorption of benzo(a)pyrene from polyethylene pellets in the marine environment

Microplastics are emerging as vectors for the transport hydrophobic organic compounds (HOCs) in aquatic environments, however, their impact is poorly understood due to the lack of field studies. In this study, the pristine and benzo(a)pyrene (B[a]P) adsorbed polyethylene (PE) pellets were placed at Haihe Estuary (Tianjin, China) for 80 days to investigate desorption behavior. Combining laboratory and in situ experiments, this study firstly verified that the intra-particle diffusion was the rate-limiting step for the desorption process of B[a]P from PE microplastics under different environmental conditions. By hindering the desorption and modifying MPs surface, biofilm might play a key role in desorption process, leading to the apparent hysteresis of the field desorption process at our time scale. Potential degradation of the polymer and B[a]P by biofilms, however, would support continuing desorption. The study explored the interaction of biofilm and MPs-contaminants mixture and its implications for the environmental fate of HOCs.

Pollution characteristics, distribution, and source analysis of carbazole and polyhalogenated carbazoles in coastal areas of Bohai Bay, China

Polyhalogenated carbazoles (PHCZs) are a class of emerging environmental contaminants formed by the substitution of hydrogen on carbazole (CZ) benzene rings with halogens (Cl, Br, I) with potential dioxin-like toxicity, and they have been frequently detected in various environmental media and organisms recently. Nevertheless, co-research of CZ/PHCZs with PAHs is very limited. In addition, I-PHCZs, which are believed to be much more toxic than CZ, Cl-PHCZs and Br-PHCZs, have a few data in sediments previously. The concentration and distribution of CZ/PHCZs and PAHs were analyzed in 18 surface sediments of Bohai Bay, China. There is a significant correlation (R = 0.64, P＜0.05) between PHCZs and PAHs, and principal component analysis (PCA) also indicating that they may have a certain similarity in origin. Additionally, total CZ and PHCZs was up to 230.57 ng/g dw in the studied samples, which was approximately 1-2 orders of magnitude lower than PAHs and other common persistent organic pollutants (POPs). The compositions of the CZ/PHCZs in our study were dominated by CZ (2.74-18.28, median 2.92 ng/g dw), 3,6-dichlorocarbazole (n.d-6.78, median 0.97 ng/g dw) and 3,6-iodocarbazole (n.d-12.68, median 1.65 ng/g dw). Results of this study discovered the varying origins of CZ and PHCZs and/or a complexity of anthropogenic influences and natural sources processes, and revealed a wide distribution of CZ/PHCZs across the studied. Moreover, more attention should be paid by comparing CZ/PHCZs with other widely distributed POPs.

Study on the distribution characteristics and metabolic mechanism of chlorine-resistant bacteria in indoor water supply networks

The presence and attachment of chlorine-resistant bacteria on the surface of water distribution network will deteriorate water quality and threaten human health. Chlorination is critical in drinking water treatment to ensure the biosafety of drinking water. However, how disinfectants affect the structures of dominant flora during biofilm development and whether the changes are consistent with the free flora remain unclear. Therefore, we investigated changes in species diversity and relative abundance of different bacterial communities in planktonic and biofilm samples at different chlorine residual concentrations (blank, 0.3 mg/L, 0.8 mg/L, 2.0 mg/L and 4.0 mg/L), and the main reasons for the development of chlorine resistance in bacteria was also discussed. The results showed that the richness of microbial species in the biofilm was higher than that in planktonic microbial samples. In the planktonic samples, Proteobacteria and Actinobacteria were the dominant groups regardless of the chlorine residual concentration. For biofilm samples, the dominant position of Proteobacteria bacteria was gradually replaced by actinobacteria bacteria with the increase of chlorine residual concentration. In addition, at higher chlorine residual concentration, Gram-positive bacteria were more concentrated to form biofilms. There are three main reasons for the generation of chlorine resistance of bacteria: enhanced function of efflux system, activated bacterial self-repair system, and enhanced nutrient uptake capacity.

Partitioning behavior and mechanism of polyhalogenated carbazoles in water and suspended particulate matter

Polyhalogenated carbazoles (PHCZs), known as new dioxin-like compounds, are a new class of emerging environmental contaminants that have received increasing attention in recent years due to their wide distribution and dioxin-like toxicity. This study investigated the partition characteristics and adsorption mechanisms of eight PHCZs in the aqueous phase and suspended particulate matter (SPM). The competitive impact of humic acid (HA) on the adsorption of PHCZs was revealed when the effects of various environmental conditions (HA, temperature, perturbation disturbance, and pH) behavior were explored. The key finding of this study is that SPM, which is its effective vector, could adsorb 70.7 % of ΣPHCZs. The equilibrium adsorption amount is ranked as 3,6-ICZ > 3,6-BCZ > 2,7-BCZ > 3,6-CCZ > 1,3,6,8-BCZ > 3-BCZ > 2-BCZ > CZ. The halogen species, the degree of halogenation, and the substitution position of the PHCZs influence the amount of adsorption, where the log K_ow values, the steric effect (E_s), and the density contribute the most to the amount of adsorption, and the specific adsorption mechanisms are van der Waals force, π-π, hydrogen bonding, and nonspecific hydrophobic interactions. The adsorption reaction of PHCZs by SPM is endothermic, and the amount of adsorption increases with increasing temperature, oscillation velocity, and decrease in pH. HA may reduce the adsorption sites of hydroxyl, carbonyl, amide groups, and π-π bonds on SPM for PHCZs, while the SPM@HA conjugates can provide new sites for the adsorption of PHCZs. According to the experimental findings of this study, SPM plays a significant role in contaminant transport. As a result, when conducting environmental investigations of PHCZs and even other hydrophobic contaminants, we must fully consider the level of contaminants present in SPM to reveal the ecological risks accurately.

Metagenomic insights into the potential risks of representative bio/non-degradable plastic and non-plastic debris in the upper and lower reaches of Haihe Estuary, China

As vectors for microorganisms and genetic elements, vast amounts of solid wastes, including plastics and non-plastics, enter oceans through estuaries globally. The heterogeneity of microbiomes developed on different types of plastic and non-plastic matrices and their potential environmental risks in field estuarine regions have not been fully explored. Here, microbial communities, antibiotic resistance genes (ARGs), virulence factors (VFs), and mobile genetic elements (MGEs) on substrate debris (SD) covering non-biodegradable plastics, biodegradable plastics, and non-plastics were first comprehensively characterized based on metagenomic analyzes (substrate identity). These selected substrates were field-exposed at both ends of the Haihe Estuary, China (geographic location). For substrate identity: conspicuously diverse functional gene profiles on different substrates were obtained; the relative gene copies of ARGs, VFs, and MGEs on non-biodegradable plastics were highest at both locations; non-biodegradable plastic matrices recruited the most abundant unique ARGs from ambient waters; the relative abundance of potential bacterial hosts carrying multiple ARGs and VFs (BH-AV) was much higher on non-biodegradable plastic surfaces than on the other two substrates, especially in the coastal water environment. For geographic locations: more abundant specific ARGs, VFs, and MGEs were significantly enriched on SD from the upper estuary; the average relative abundance of identified BH-AV on SD from the upper estuary was 1.99-7.14 folds from the lower estuary. Finally, the results of the Projection Pursuit Regression model verified the higher comprehensive potential risks arising from non-biodegradable plastics (substrate identity) and SD from the upstream of the estuary (geographic location). Based on comparative analysis, our results alert us to pay particular attention to ecological risks triggered by conventional non-biodegradable plastics in rivers and coastal environments and highlight the microbiological risk from terrestrial solid waste to the downstream marine environment.

Field based studies on aging characteristics of pristine and aged plastic debris in a coastal environment, Bohai Bay, China

The coastal environment has become a sink of plastic due to the strong impact of plastic waste input from land. Plastics entering a coastal environment usually experience aging on land. However, few previous studies used aged plastics to study plastic aging in seawater, and the aging characteristics of aged plastics in a coastal environment are unclear. In our study, a ten-week investigation of the aging characteristics of pristine and pre-aged polypropylene plastic debris was conducted in Bohai Bay, China. During ten-week field exposure, more biofilms formed on the surfaces of pre-aged plastic debris than pristine plastic debris. However, no significant differences were found in the physicochemical properties (surface chemistry, hydrophobicity, and crystallinity) between pristine and pre-aged plastic debris. In addition, the results of redundancy analysis (RDA) illustrated that temperature was a key factor influencing the aging characteristics of plastic debris. Our research suggests that the aging history can affect the density of plastic debris by affecting the adhesion of the biofilm, which may influence the fate of plastic debris. In a coastal environment, plastic debris at different aging stages with the same initial chemical composition had basically similar changes in physicochemical properties in the short term.

The convergence of 2,6-dichloro-1,4-benzoquinone in the whole process of lignin phenol precursor chlorination

The formation and decomposition of 2,6-dichloro-1,4-benzoquinone, an emerging disinfection byproduct (DBP), was studied in the chlorination of lignin phenol precursors. The results show that DCBQ and the related hydroxyl DCBQ (DCBQ-OH) acts as the intermediate products of the chlorination process of the three typical lignin phenol precursors (p-hydroxybenzoic acid, protocatechuic acid, and gallic acid). The contributions of lignin phenol precursors to the overall formation of the targeted DBPs were determined based on the observed abundances of individual lignin phenols and their DBP yields. DCBQ and DCBQ-OH were generated within 2-6 h, the relative abundance of the yields of mol carbon atoms in DCBQ corresponding to the mol carbon atoms in the three model precursors (DCBQ-C) was about 0.01%-14.37% under different pH conditions. With the chlorination reaction time increased (after two or four h), the concentrations of DCBQ and DCBQ-OH entirely decreased, and the decomposition of DCBQ do not follow a pseudo-first-order kinetics during chlorination. Conversely, the decomposition of DCBQ generated from p-hydroxybenzoic acid followed a pseudo-second-order kinetics. Moreover, the formation of trichloromethane (TCM), dichloroacetic acid (DCAA), and trichloroacetic acid (TCAA) was also detected during the chlorination. The contribution of the decomposed DCBQ was mainly to TCAA and the unknown DBPs within 2-12 h, and DCBQ decomposition pathway was affected by pH. Moreover, except for DCBQ/DCBQ-OH and TCM/HAAs, there were still 73.6%-92.41% unknown products (including non-halogenated aromatic DBPs and chlorine-substituted DBPs) needing to identify during the chlorination process for lignin phenols. Overall, revealing the formation and decomposition of DCBQ during the chlorination of lignin phenol precursors would contribute to the effective development of drinking water treatment processes for the removal of highly toxic intermediates generated during disinfection.

[Analysis of the application of radiotherapy facility construction project evaluation standard in health management institutions]

Objective: To investigate the application of GBZ/T 220.2-2009 "The Specification of Radiological Protection Assessment for Occupational Hazard in Construction Project-Part 2: Radiotherapy Facility" in health management institutions, and to understand the scientificity, practicability and problems existing in the implementation of the standard. Methods: The method of multistage stratified sampling and questionnaire survey were used to collect the standard application status among 96 radiological health managers who had participated in the evaluation of radiotherapy facility construction projects in 6 provinces and cities from November 2020 to April 2021. A descriptive statistical analysis method was used to analyze the basic information of the survey object, the knowledge of the standard, the publicity and implementation of the standard. Results: The radiological health management personnel mainly came from health supervision agencies (62.5%, 60/96) , and 86.5% (83/96) were engaged in the pre-evaluation of radiotherapy device construction project and the approval and supervision of control effect evaluation. The awareness rate and training rate of radiological health managers on GBZ/T 220.2-2009 were 88.5% (85/96) and 31.3% (30/96) , respectively. 89.6% (86/96) managers thought it could meet the needs of radiotherapy facility construction project approval or supervision. 49.0% (47/96) of managers believed that the standard needed to be revised. Conclusion: The content of GBZ/T 220.2-2009 is basically scientific and reasonable, but the publicity, implementation and training of radiological health administrator still need to be strengthened. It is suggested to revise some clauses in the standard that do not meet the requirements.

Antibiotics and resistant genes in the gut of Chinese nine kinds of freshwater or marine fish

Antibiotic resistance genes (ARGs) may lead to bacterial resistance and using antibiotics will promote ARGs spread. Large amounts of antibiotics were used in aquaculture, but little attention was paid to the antibiotic resistant in fish gut. In this study, nine kinds of Chinese freshwater and marine fish were acquired in a city of northern China to test the amount of antibiotics and ARGs residues in their intestinal contents. The results showed that 4 kinds of antibiotics were detected from the intestinal contents, including Doxycycline (DOX), Tetracycline (TC), Sulfamethoxazole (SMX) and Roxithromycin (ROX), and the antibiotics with the largest detected amount was ROX in Sardinops sagax (2.83 μg kg^-1). Ten kinds of ARGs were detected from the intestinal contents, including strA, strB, ermB, bla_TEM, oxa-30, qnrB, qnrD, sul1, sul2 and tetB, as well as one type of integron intI1. The most abundant ARGs were bla_TEM. Correlation analysis showed huge difference between freshwater fish and marine fish. The results can improve our understanding of the antibiotics and ARGs residues in edible fish.

A Methodology for Reconstructing Source Properties of a Conical Piezoelectric Actuator Using Array-Based Methods

We investigated the force produced by a conical piezoelectric (PZT, lead zirconate titanate) transducer actuated by high voltage pulses (HVP) in contact with a steel transfer plate. Using elastic wave propagation theory in a semi-infinite plate, we aimed to quantify the magnitude and estimate the shape of the force-time function via the body waves produced in the transfer plate using the displacement field recorded on an array of 20 absolutely calibrated PZT receivers. We first calibrated the receiver array using glass capillary fracture. We proceeded to use a conical PZT transducer to actively produce a source at the origin, allowing us to study the displacement field produced on the now calibrated PZT receiver array. We studied two types of HVP: An impulsive and step source. The calibrated receiver array was used to estimate the general shape of the force-time functions for each type of HVP. From our hypothesized force-time functions we were able to estimate the peak force produced by the PZT actuator: The impulsive source generated a force of f peak = 2.90 ± 0.42 N and the step source generated f peak = 1.79 ± 0.30 N, respectively, for a peak applied voltage of 273 V. This translates to an applied force of ∼ 0.011 N/V and 0.007 N/V for the impulse and step force-time functions, respectively, which is similar to estimates found in the literature for other conical transducers in contact with metallic transfer media. This measurement was verified directly by independent measurements of the peak force f peak using a dynamic force transducer. We found that our methodology correctly estimated the magnitude of the force but is limited to transducers with incident angles θ < 53 ∘ . Beyond this angle, overestimates of the force were observed due to the lack of body wave energy produced by the source. These results allow us to quantitatively determine the forces produced by active PZT techniques using only the measurement of the displacement field captured on a calibrated conical PZT array. Quantitative understanding of active PZT sources additionally constrains the transfer functions approach, which is commonly used in the non-destructive testing of materials and in other fields, such as rock physics and laboratory seismology.

Occurrence of legacy and emerging poly- and perfluoroalkyl substances in water: A case study in Tianjin (China)

Due to the water solubility and environmentally persistent properties of poly- and perfluoroalkyl substances (PFAS), the contamination of PFAS in drinking water is raising widespread concerns for their potential adverse health risks. In the present study, the behavior of PFAS from source waters to effluent water was analyzed by taking samples from three drinking water sources (Yuqiao Reservoir, Beidagang Reservoir, and Yangtze River) and effluent of several treatment processes used in one drinking water treatment plant (DWTP) of Tianjin (China), including pre-chlorination, coagulation, sand filtration, and chlorination. The range of total concentration of PFAS (∑₂₁PFAS) in three source water was 6.64-19.80 ng/L (Yuqiao Reservoir), 80.00-119.86 ng/L (Beidagang Reservoir), and 15.87 ng/L (Yangtze River), respectively. As for individual PFAS, PFBA (perfluorobutanoic acid) was the most abundant PFAS, followed by PFOA (perfluorooctanoic acid), PFBS (perfluorobutane sulfonate), and PFOS (perfluorooctane sulfonate), especially, 6:2 Cl-PFESA (6:2 Cl-polyflurinated ether sulfonate) was detected in all samples. During treatment, the removal rate of ∑₂₁PFAS was 11%, and the removal rate of long-chain PFAS such as PFNA (perfluorononanoic acid), PFOS, and PFDS (perfluorodecane sulfonate) were relatively higher than short-chain PFAS due to their hydrophobic characteristic. Besides, the influence of seasonal factor (precipitation) on the occurrence and composition characteristics of PFAS in the aquatic environment was also investigated, and the results demonstrated that precipitation affected the total concentrations of PFAS in the aquatic environment, but barely on the composition characteristics of PFAS. Furthermore, the ecological risks could be negligible based on the concentration of PFAS measured in surface water. In the meanwhile, the health risks were also assessed based on the concentration of PFAS detected in drinking water, the result indicated that the concentrations of PFAS were less than the suggested drinking water advisories. In addition, more attention should be paid to the risk caused by the frequently detected emerging PFAS such as 6:2 Cl-PFESA and HFPO-DA (hexafluoropropylene oxide-dimer acid).

A single-arm pilot of a web-based intervention to improve itch-related quality of life

BACKGROUND

Many patients with chronic itch and atopic dermatitis (AD) or psoriasis do not receive/use available medical and psychosocial treatments properly due to system, provider and/or patient factors.

OBJECTIVE

An educational website (ITCH-RELIEF) to improve itch-related quality of life (QoL) for adults with AD or psoriasis and chronic itch was developed and assessed. ITCH RELIEF stands for Interactive Toolbox of Comprehensive Health Resources to Enhance Living with Itch - Educational Facilitation (for Adults).

METHODS

Single-arm pre- and post-test design with 1-month follow-up (N = 137 at baseline).

RESULTS

There was statistically and clinically significant improvement in the primary outcome of itch-related QoL impairment as assessed by the ItchyQoL from baseline [M = 78.9, 95% confidence interval (CI) = 75.9, 81.9] to follow up (M = 75.4, CI = 72.4, 78.5), P = 0.007, as well as statistically significant improvement in several itch-related secondary outcomes (all Ps < 0.05).

CONCLUSIONS

This study demonstrated initial effectiveness of an online intervention to improve itch-related QoL among individuals with AD or psoriasis and chronic itch. Future studies should address limitations by randomizing more heterogeneous participants, utilizing a longer follow-up and assessing medication use.

Psychosocial adjustment mediates impacts of playmate positive support on body mass index and overweight risk in adolescents

OBJECTIVES

We examined the mediation effects of psychosocial adjustment on the impact of playmate positive support throughout childhood and early adolescence (from age 54 months to 11 years) on later body mass index (BMI) and overweight risk in middle adolescence (age 15 years).

STUDY DESIGN

This was a prospective cohort study.

METHODS

Among 844 children and their families, positive support between child-playmate dyads was repeatedly assessed from child's age 54 months to Grade 5. Long-term positive support between child-playmate dyads throughout childhood and early adolescence was prospectively linked to child's BMI and overweight/obesity status at age 15 years. The average scores of repeated assessments of internalizing and externalizing behavior problems from Grades 3 to 6 were used as mediators.

RESULTS

Significant mediations of internalizing and externalizing behavior problems were observed on pathways from positive support between child-playmate dyads to later BMI and overweight/obesity status at age 15 years. The observed mediations were mainly sustained with pronounced magnitudes in girls, but not in boys.

CONCLUSIONS

Our findings demonstrated a significant mediating role of psychosocial adjustment. Future research efforts are highly encouraged to replicate our findings and further explore this underlying mediation mechanism.

Iodide promotes bisphenol A (BPA) halogenation during chlorination: Evidence from 30 X-BPAs (X = Cl, Br, and I)

As a well known endocrine-disrupting and model chemical, bisphenol A (BPA) may pose a serious threat to human health, since it and its disinfection by-products (DBPs) have been detected in drinking water, urine, human colostrum, adipose tissue, and placenta samples. Although chlorinated BPAs (Cl-BPAs) and iodinated BPAs (I-BPAs) have been well studied, brominated BPAs (Br-BPAs), and mixed halogenated DBPs like bromo-iodo-BPAs (Br-I-BPAs), and bromo-chloro-iodo-BPAs (Cl-Br-I-BPAs) are less well understood. Notably, the role of iodide (I^-) during chlorination is not well understood, since the studies of the I-DBPs mainly focus on their genotoxicity and cytotoxicity. To understand the formation mechanisms of halogenated bisphenol A (HBPs) during chlorination with bromide (Br^-) and/or I^-, and the role of I^- during chlorination, three set of reactions were performed in the laboratory ("BPA + chlorine + Br^-", "BPA + chlorine + I^-" and "BPA + chlorine + Br^- +I^-" assigned as group A, B and C respectively). Thirty HBPs were identified and 18 of them were never reported before. I^- increases the transformation rate of BPA into HBPs as I-BPAs act as intermediate HBPs during chlorination that easily react with HClO/ClO^- and HBrO/BrO^- to form Cl-BPAs and Br-BPAs. HIO/IO^- showed higher reactivity towards BPA and HBPs than that of HBrO/BrO^- and HClO/ClO^-. The recycling of I^- was observed in the reactions of "BPA + chlorine + I^-" and "BPA + chlorine + Br^- +I^-", which may explain why I^- can induce BPA to transform into HBPs and suggests that I^- may act as a catalyst during the BPA chlorination reactions. The reaction pathways are proposed which present the reactions of BPA and HBPs with HClO/ClO^-, HBrO/BrO^-, and HIO/IO^-, as well as the recycling of I^-. This study describes the potential DBP formation and transformation mechanisms of BPA and its 16 alternatives, as well as the role of I^- on the transformation of phenol compounds during chlorination.

Hydrolysis characteristics and risk assessment of a widely detected emerging drinking water disinfection-by-product-2,6-dichloro-1,4-benzoquinone-in the water environment of Tianjin (China)

Halobenzoquinones (HBQs) are an emerging class of drinking water disinfection byproducts (DBPs) that have been frequently detected in drinking water and are highly relevant to bladder cancer. Among the studied HBQs, 2,6-dichloro-1,4-benzoquinone (DCBQ) had the highest detection frequency and concentrations in drinking water. However, compared to other countries, the studies on HBQs that are being conducted in China, especially those on HBQs in drinking water, are not sufficient. Therefore, the concentrations of DCBQ in the Tianjin drinking water supply system were investigated in two seasons (winter and summer), and the risk that is posed by DCBQ in drinking water was evaluated for the first time. In addition, since HBQs are prone to hydrolysis in neutral and alkaline environments, identification of the hydrolytic characteristics of DCBQ at various pH values and in the real water environment is essential for better describing the environmental behavior of DCBQ; hence, the hydrolysis characteristics of DCBQ in phosphate buffers with various pH values and in four water samples were also examined in our study. The results demonstrated that DCBQ was widely detected in the drinking water treatment process and distribution systems, and the average concentration in our study (12.0 ng/L) was at a moderately high level compared with the reported concentration of DCBQ in the drinking water distribution networks. The risk quotient (RQ) of DCBQ is equivalent to that of trihalomethanes (THMs); thus, the relatively low concentrations of DCBQ should also be considered. Furthermore, the results demonstrated that the hydrolysis of DCBQ follows first-order reaction kinetics, the reaction rate accelerates as the pH of the phosphate buffer system increases, and the rate of hydrolysis of DCBQ in drinking water is affected not only by the pH but also by other environmental factors, such as the organic matter concentration. Therefore, further investigation is necessary to identify the main factor of DCBQ hydrolysis in real water environments.

Colonization characteristics of bacterial communities on plastic debris: The localization of immigrant bacterial communities

The unique characteristics of bacterial communities on plastic debris and microplastics in the environment have been widely studied in recent years. However, due to the randomness of sampling, it is hard to identify whether the unique characteristics of bacterial communities on plastic debris is due to the plastics as substrate itself, or the accumulation and transportation by plastics. Therefore, the ecological effects of bacterial communities on plastic debris, including the species invasion, are still not clear. To investigate such issue, we took the Haihe Estuary (Tianjin, China) as an example, and designed a strategy to sample and redeploy randomly collected environmental plastic debris for 6 weeks, thus the variation of bacterial communities on plastic debris could be assessed. At the same time, commercial experimental plastic debris was used as the control group to monitor the growth of local bacterial communities on plastics in the cultivation environment. Our study discussed the bacterial communities on the environmental plastic debris from three aspects, including colonization characteristics, taxonomic analysis and molecular metabolism estimation. We found that the bacterial communities on environmental plastic debris tended to show local characteristics, which were less affected by their original characteristics. Therefore, the results reminded us that the ecological risks of bacterial communities on plastics, which were brought by the transportation of plastic debris in the environment, may not be as serious as it was expected previously.

Mobile genetic elements are the Major driver of High antibiotic resistance genes abundance in the Upper reaches of huaihe River Basin

Rivers are considered a vital reservoir of antibiotic resistance genes (ARGs) and are critical to disseminate ARGs. The present study delved into the ARGs pollution of the sediments in the upper reaches of Huaihe river, one of the seven longest rivers in China, by high-throughput quantitative PCR. Subsequently, the relationship between ARGs and the bacterial community/mobile genetic elements (MGEs) was determined. As revealed from the results, the overall ARGs ranged from 2.65×10^-3 to 6.14×10^-2/16S copies, and the abundance of ARGs in the tributaries was significantly higher than that in the mainstreams (p<0.05). Moreover, the ARGs introduced by tributaries were capable of affecting the whole mainstream of Huaihe river. As suggested from the results of co-occurrence analysis and pRDA analysis, MGEs were reported as the major driver to disseminate ARGs in the upper reaches of Huaihe river basin. The larger the MGEs proportion, the higher the likelihood of ARGs transferring from antibiotic resistance bacteria to human pathogens in Huaihe river.

Diagnostic efficacy of contrast-enhanced ultrasound versus MRI Liver Imaging Reporting and Data System (LI-RADS) for categorising hepatic observations in patients at risk of hepatocellular carcinoma

AIM

To investigate the diagnostic efficacy of the contrast-enhanced ultrasound Liver Imaging Reporting and Data System (CEUS LI-RADS) for categorising hepatic observations in patients at risk of hepatocellular carcinoma (HCC) compared with magnetic resonance imaging (MRI) LI-RADS.

MATERIALS AND METHODS

CEUS and MRI data were analysed retrospectively according to the LI-RADS scheme. Follow-up results and pathological findings served as the reference standard. Receiver operating characteristic (ROC) curve analysis was used to reveal the area under the curve (AUC). The sensitivity, specificity, accuracy, and positive (PPV) and negative predictive values (NPV) of LR-5 for determining HCC were calculated. The intra-observer agreement of CEUS LI-RADS was also evaluated.

RESULTS

Eighty-four patients with 86 liver observations were enrolled. Forty-two observations were classified as LR-5 by CEUS and MRI, respectively. Based on the reference standard, 53 nodules were HCC. The AUCs were 0.876 for CEUS and 0.873 for MRI, without a significant difference (Z=0.050, p=0.960). The sensitivity, specificity, PPV, NPV, and accuracy of LR-5 was 75.47%, 93.94%, 95.24%, 70.45%, 82.56% with CEUS and 73.58%, 90.9%, 92.86%, 68.18%, 80.23% with MRI, respectively. There was a significant difference in specificity between CEUS and MRI (p=0.006). There was almost perfect agreement for arterial phase hyperenhancement (k=0.870), substantial agreement for washout (k=0.765) and CEUS LI-RADS category (k=0.787).

CONCLUSION

The CEUS LI-RADS scheme is an effective diagnostic tool for HCC with substantial intra-observer reliability. The diagnostic performance of CEUS LI-RADS for determining HCC was comparable to MRI LI-RADS, and the specificity of CEUS LR-5 was significantly higher.

Co-effects of biofouling and inorganic matters increased the density of environmental microplastics in the sediments of Bohai Bay coast

Size, shape and color are the basic parameters of environmental microplastic (MPs). However, the density of microplastics which is an important parameter to influence the fate of MPs in the environment has not been measured. Meanwhile, the MPs characteristics from coastal sediments of Bohai Bay remain unclear. In this study, the concentrations, distribution and composition (shapes and sizes) of MPs were investigated. The average concentration of MPs in the coastal sediments of Bohai Bay was 192.3 ± 138.9 items/kg dw, which was at a moderate pollution level. The MPs with fiber shape (54.5%), small size (52.0%) and low density (PE and PP) were dominant. In addition, flotation experiment showed that most of PE and PP had the higher density compared with seawater. Digestion experiments suggested that the density change of MPs was caused by the co-contribution of biofouling and inorganic minerals. The density increasing rates of PE and PP were 7.4%-12.6% and 12.1%-17.5%, respectively. Finally, we also estimated that the total number of MPs in the sediments of Bohai Sea was 534 trillion, which were significantly higher than that in global ocean surface, suggesting that the coastal sediments could be the sink of MPs.

Colonization characteristics of bacterial communities on microplastics compared with ambient environments (water and sediment) in Haihe Estuary

The bacterial communities on microplastics in marine and freshwater environments have been described by many studies. However, the migration and transportation processes of bacterial communities on microplastics in estuarine areas remain unclear. In this study, the bacterial communities on three substrates (microplastics, surface water and sediment) in estuarine areas (the Haihe Estuary (HHE) in Bohai Bay, China) were investigated based on 16S rRNA sequencing. The mean OTUs of the three substrates - water, microplastics and sediments - were 1091, 2213 and 3419, respectively. The partitioning of the OTUs among the three substrates indicated that the microplastics could be messengers facilitating the bacterial transportation between water and sediment. According to nMDS and relative abundance analyses, it was found that the microplastics enriched the particular bacteria (e.g., Halobacteriaceae and Pseudoalteromonadaceae) and weakened the influence of environmental variation. In addition, taxonomic and metabolic-pathway analyses indicated that the abundance of potentially pathogenic bacteria (e.g., Pseudomonas and Bacillus) on microplastics was significantly higher than that in the ambient environment. Meanwhile, the microplastic polymer types had little effect on the abundance and structure of the bacterial communities. Compared with surface water and sediments, microplastics could be a good habitat for bacterial communities and could lead to potential ecological risks because of the high stability, pathogenicity and stress tolerance of the bacterial communities on microplastics.

Legacy per- and polyfluoroalkyl substances (PFASs) and alternatives (short-chain analogues, F-53B, GenX and FC-98) in residential soils of China: Present implications of replacing legacy PFASs

With the worldwide regulation of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), the alternatives (short chain analogues and emerging per- and polyfluoroalkyl substances, PFASs) have gradually attracted global attention. This study analysed the replacing of legacy PFASs in China using PFASs data from residential soils, which might be good environmental indicators of their present usage. The total concentrations of 21 PFASs ranged from 244 to 13564 pg/g, and PFOA was the dominant compound among the studied PFASs, with a concentration of 354 ± 439 pg/g. Serious PFASs pollution in residential soils mainly occurred in Eastern Coastal China as a result of locally developed industry and economies. Weak but significant correlations were found between PFASs and environmental and socioeconomic factors, suggesting that various factors determine PFASs contamination in residential soils. The concentration and detection frequency (DF) of short-chain analogues (C < 8) (375 ± 509 pg/g and 100%), and F-53B (216 ± 306 pg/g and 98.9%) were higher than those for PFOS (193 ± 502 pg/g and 85.4%), indicating that these compounds have been widely used as PFOS alternatives and their consumption has already exceeded that of PFOS in China. In addition, GenX (the PFOA alternative) had a concentration and DF of 19.1 ± 104 pg/g and 40.5%, respectively. These values were much lower than those for PFOA (354 ± 439 pg/g and 96.6%), indicating GenX consumption is still limited at the national scale of China, despite its use as a PFOA replacement. Moreover, the low concentration and DF of FC-98 (2.31 ± 11.1 pg/g and 27.0%) indicate that its consumption might be negligible. Our study demonstrated that short chain analogues and emerging alternatives have become the dominant PFAS pollutants in Chinese residential soils, and further studies need to be conducted to understand their toxicity and environmental risks.

Estuarine sediments are key hotspots of intracellular and extracellular antibiotic resistance genes: A high-throughput analysis in Haihe Estuary in China

Estuaries lie between terrestrial/freshwater and marine ecosystems, receive considerable pollutant input from land-based sources, and are considerably influenced by human activities. However, little attention has been paid to combined research on extracellular antibiotic resistance genes (eARGs) and intracellular ARGs (iARGs) in the estuarine environment. In this study, we profiled eARGs and iARGs in sediments from Haihe Estuary, China by adopting high-throughput quantitative PCR and investigated their relationship with mobile genetic elements (MGEs), the bacterial community and environmental factors. The results showed that the abundance of eARGs ranged from 9.06 × 10⁶ to 1.32 × 10⁸ copies/g and that of iARGs ranged from 3.31 × 10⁷ to 2.93 × 10⁸ copies/g, indicating that estuarine sediments were key hotspots of eARGs and iARGs. Additionally, multidrug resistance genes were both highly diverse and abundant in Haihe Estuary, especially in coastal samples. The high abundance of vancomycin and carbapenemase resistance genes may pose a potential health risk to human. Salinity altered the composition and structure of the bacterial community. Partial redundancy analysis showed that the bacterial community and MGEs appeared to be the major drivers of ARG variance in estuarine sediment. This study provides an overview of the distribution of eARG and iARG along the Haihe Estuary and draws attention to the need to control pollutants in estuary ecosystems.

Antibiotic Resistance Genes in drinking water of China: Occurrence, distribution and influencing factors

Drinking water samples were collected from 71 cities, including 28 provincial capital cities or municipalities, 20 prefecture cities and 23 counties, of 31 provincial-level administrative regions in China from July to August in 2017. Futhermore, 24 Antibiotic Resistance Genes (ARGs), 16S rRNA and 2 integrase genes were quantified by qPCR to investigate the pollution degree of ARGs. The results revealed that the 16S ranged from 10⁵ - 10⁸ copies/100 mL in the drinking water, and its treatment process could effectively remove bacteria. Moreover, sulfonamides-ARGs were the most prevalent ARGs in the drinking water of China, and the abundance of bla_TEM ranked top five in all cities among the selected ARGs, indicating that the pollution condition of the genes should be aroused more attention. The data of qPCR and correlation analyses indicated that intI1 played a more crucial role than intI2 in the propagation of ARGs in the drinking water. Additionally, the pollution degree of ARGs among different city types showed no significant difference.

Large-scale distribution of organophosphate esters (flame retardants and plasticizers) in soil from residential area across China: Implications for current level

To recognize the occurrence and health risk of organophosphate esters (OPEs) in soil of residential areas, a nationwide survey was conducted covering 32 provincial-level administrative regions of China in 2018. Except for triamyl phosphate (TAP), twelve OPEs were detected in residential soil from 89 cities with a total concentration of 1.70-179 ng/g dw, indicating a relatively low contamination level of OPEs in residential soil of China (compared with point source soils and urban soils). Tris(1-chloro-2-propyl) phosphate (TCIPP) was the most abundant OPEs, followed by tris(2-butoxyethyl) phosphate (TBOEP), tris(2-chloroethyl) phosphate (TCEP) and triphenyl phosphate (TPHP), which suggested that TCIPP has been a replacement of TCEP in recent years. An apparent geographical distribution of higher OPEs levels in the Bohai Rim, the Yangtze Delta and Shanxi province than other regions was found. According to the division of administrative levels, the most serious OPEs pollution occurred in prefecture-level city (20.2 ng/g dw), followed by provincial capital (17.9 ng/g dw) and county town (14.1 ng/g dw), which was affected by the usage of OPEs products and behaviors of local residents. The correlation analysis results showed that environmental parameters (total organic carbon (TOC), precipitation and temperature) were not the major factors determining OPEs contamination, while socioeconomic parameters were significantly correlated with OPEs concentration in undeveloped regions/cities with rare industrial source. Although the health risk assessment suggested a negligible risk to local residents (5.92 × 10^-7-1.75 × 10^-6 for non-carcinogenic risk and 4.82 × 10^-12-2.10 × 10^-11 for carcinogenic risk), the production and usage of TCIPP and TCEP should be paid more attention due to their relatively high risks. Our study was attempted to provide a nationwide baseline concentration of OPEs in soil of residential areas, which could be used to support further studies.

How long-term exposure of environmentally relevant antibiotics may stimulate the growth of Prorocentrum lima: A probable positive factor for red tides

Antibiotics have been widely detected in the ocean and have various impacts on the environment, while knowledge of their chronic influence on phytoplankton, especially red tide algae, is still limited. Dinoflagellates and green algae are common phytoplankton in marine ecosystems. The former is the main red tide algae, and the latter is an important primary producer. We investigated the long-term responses of two representative algae, Prorocentrum lima and Chlorella sp., to two common antibiotics (sulfamethoxazole (SMX) and norfloxacin (NFX)) at environmentally relevant levels (10 and 100 ng/L) during simulated natural conditions. The cell density and activities of three antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD)) were analyzed. The results showed that the influence of each antibiotic on Chlorella sp. was not significant (p > 0.05) during the first 10 days, but the influence of the antibiotics later began to show significant inhibition (p < 0.05) compared with the control group, especially during mixed exposure. P. lima was not inhibited, but its cell density increased. SMX had a superior stimulation effect on P. lima. The three enzymes activities of P. lima increased, and the antioxidant mechanism was not seriously impacted. However, for Chlorella sp., the activity of SOD increased while the activities of CAT and POD decreased, suggesting that this algae's antioxidant system was unbalanced due to oxidative stress. Based on our results, the growth of P. lima was different from green algae Chlorella sp. as well as other inhibited marine algae (such as diatom, golden algae) studied in previous studies. Therefore, as a typical pollutant in the ocean, antibiotics may play a positive role in the bloom of dinoflagellate red tides.

Colonization Characteristics of Bacterial Communities on Plastic Debris Influenced by Environmental Factors and Polymer Types in the Haihe Estuary of Bohai Bay, China

The colonization characteristics of bacterial communities on microplastics or plastic debris (PD) have generated great concern in recent years. However, the influence of environmental factors and polymer types on the formation of bacterial communities on PD in estuarine areas is less studied. To gain additional insights, five types of PD (polyvinyl chloride, polypropylene, polyethylene, polystyrene, and polyurethane) were exposed for three-time periods (two weeks, four weeks, and six weeks) in the Haihe Estuary. 16S rRNA gene sequencing was used to identify the bacterial communities on PD, in seawater, and in sediment samples. The results indicate that the average growth rate of a biofilm is affected by nutrients (total nitrogen and total phosphorus) and salinity. Furthermore, salinity is the primary factor affecting bacterial diversity of the colonies on PD. In addition, genera of bacteria show selectivity toward the PD polymer type and tend to colonize their preferred substrate. Compared with seawater and sediment, PD could be carriers for enrichment of Vibrio in the estuarine environment with salinity ≥26 (± 2‰), which might increase the ecological risk of PD in marine environments.

The effect of environmentally relevant emerging per- and polyfluoroalkyl substances on the growth and antioxidant response in marine Chlorella sp

The 6:2 chlorinated polyfluoroalkyl ether sulfonic acids (6:2 Cl-PFAES), 2,3,3,3-tetrafluoro-2-(1,1,2,2,3,3,3-heptafluoropropoxy)-propanoic acid (HFPO-DA) and perfluoroethylcyclohexane sulfonate (PFECHS) are emerging per- and polyfluoroalkyl substances (PFASs) that are being applied to replace phased-out PFASs, which have high persistency, high bioaccumulation potential and high toxicity. Recently, these emerging PFASs were observed in estuary and marine areas with a pollution level of ng/L. In this study, three levels (10 ng L^-1, 100 ng L^-1 and 1000 ng L^-1) for these PFASs were selected to investigate the response of marine Chlorella sp. to 14 days of exposure. The growth of Chlorella sp. was significantly inhibited by each PFAS over time. Treatments with 1000 ng/L exposure caused the most severe reduction in growth for each PFAS treatment. For the first half of the experimental period (from Day 0 to Day 6), the influence of each PFAS was not significant (p > 0.05). However, treatments with all concentrations of 6:2 Cl-PFAES, HFPO-DA and 1000 ng L^-1 PFECHS significantly reduced the growth of Chlorella sp. from Day 8. The superoxide dismutase (SOD) activities in Chlorella sp. were significantly increased (p < 0.05) when exposed to 6:2 Cl-PFAES, HFPO-DA and PFECHS. The catalase (CAT) and peroxidase (POD) activities in Chlorella sp. were significantly inhibited (p < 0.05) by each PFAS. The glutathione (GSH) contents in Chlorella sp. were significantly increased by each PFAS. However, the increases in GSH concentration in Chlorella sp. were low. The inhibition of algal growth was primarily due to the reduction of the activities of CAT and POD. PFECHS had the lowest toxicity among the three PFASs, and it induced less oxidized damage to Chlorella sp. In conclusion, as alternatives to phased-out PFASs, the emerging PFASs are not safe in aquatic environment, and attention should be paid to the management and restriction of these emerging PFASs.

Pollution of polycyclic aromatic hydrocarbons (PAHs) in drinking water of China: Composition, distribution and influencing factors

Polycyclic aromatic hydrocarbons (PAHs) are a kind of persistent toxic substances, which have been frequently detected in environmental media. However, studies on their occurrences and distributions in drinking water are insufficient and their composition profiles in drinking water are still not clear. In this study, we investigated 16 priority polycyclic aromatic hydrocarbons (PAHs) in drinking water from different administrative level cities throughout mainland China, analyzed the influences of anthropogenic activities on PAHs, and assessed the health risk of the PAHs in drinking water. On the national scale, the sum concentration of the 16 priority-controlled PAHs (∑₁₆PAHs) designated by the U.S. Environmental Protection Agency (USEPA) was in a range of 3.89-231.39 (mean 56.25) ng L^-1. With the decline of ∑₁₆PAHs, the concentration of 3-ring PAHs decreased, while its proportion increased, indicating 3-ring PAHs might be more difficult to remove than other PAHs in drinking water. The geographical distribution of PAHs in drinking water of China was in a descending order of West (69.81 ng L^-1) > South (61.95 ng L^-1) > North (58.63 ng L^-1) > East (39.21 ng L^-1) > Northeast China (37.93 ng L^-1). ∑₁₆PAHs in drinking water of Prefecture-level City was the greatest (71.49 ng L^-1) followed by Provincial Capital (52.12 ng L^-1), County-level City (50.98 ng L^-1) and Municipality (33.92 ng L^-1). ∑₁₆PAHs was significantly negatively correlated with the per capita GDP of sampling city (P < 0.01, n = 78), implying that waterworks is an effective way to control and reduce PAH pollution in drinking water. The carcinogenic risk of the 16 PAHs in drinking water of China was much greater than the non-carcinogenic risk.

Occurrence and distribution of microplastics in the surface water and sediment of two typical estuaries in Bohai Bay, China

Estuaries are considered to be seriously polluted by microplastics. As the most important water body in North China, the pollution level of microplastics in two typical estuaries (Haihe Estuary (HHE) and Yondingxinhe Estuary (YDXE)) of Bohai Bay is not well understood. The occurrence and distribution of microplastics in the surface water and sediment of HHE and YDXE were investigated. The mean concentration of microplastics in surface-water samples was 1485.7 ± 819.9 items per m3 for HHE and 788.0 ± 464.2 items per m3 for YDXE, respectively, whereas the concentration of microplastics in sediment was 216.1 ± 92.1 items per kg dw for HHE and 85.0 ± 40.1 items per kg dw for YDXE, respectively. The concentration of microplastics in surface-water and sediment-samples of HHE was higher than that of YDXE, though YDXE is a typical sewage-received river. Anthropogenic activities and the river input were the main sources of microplastic pollution in estuarine areas. Sewage rivers could be point sources of microplastic pollution on a small scale. The small size (particle diameter < 1 mm) of microplastics was a dominant feature, the most abundant shape was fiber and colored microplastics were found widely in YDXE and HHE. We provided detailed information on microplastic pollution to support their control and management in HHE and YDXE.