The effects of 17α-methyltestosterone on gonadal histology and gene expression along hypothalamic-pituitary-gonadal axis, germ cells, sex determination, and hypothalamus-pituitary-thyroid axis in zebrafish (Danio rerio).

As a synthetic androgen, 17α-methyltestosterone (MT) is widely used in aquaculture to induce sex reversal and may pose a potential risk to aquatic organisms. This ecological risk has attracted the attention of many scholars, but it is not comprehensive enough. Thus, the adverse effects of MT on zebrafish (Danio rerio) were comprehensively evaluated from gonadal histology, as well as the mRNA expression levels of 47 genes related to hypothalamic-pituitary-gonadal (HPG) axis, germ cell differentiation, sex determination, and hypothalamus-pituitary-thyroid (HPT) axis. Adult zebrafish with a female/male ratio of 5:7 were exposed to a solvent control (0.001% dimethyl sulfoxide) and three measured concentrations of MT (5, 51 and 583 ng/L) for 50 days. The results showed that MT had no significant histological effects on the ovaries of females, but the frequency of late-mature oocytes (LMO) showed a downward trend, indicating that MT could induce ovarian suppression to a certain extent. The transcriptional expression of activating transcription factor 4b1 (atf4b1), activating transcription factor 4b2 (atf4b2), calcium/calmodulin-dependent protein kinase II delta 1 (camk2d1), calcium/calmodulin-dependent protein kinase II delta 2 (camk2d2) and calcium/calmodulin-dependent protein kinase II inhibitor 2 (camk2n2) genes in the brain of females increased significantly at all treatment groups of MT, and the mRNA expression of forkhead box L2a (foxl2) and ovarian cytochrome P450 aromatase (cyp19a1a) genes in the ovaries were down-regulated by 5 and 583 ng/L group, which would translate into inhibition of oocyte development. As compared to females, MT had relatively little effects on the reproductive system of males, and only the transcriptional alterations of synaptonemal complex protein 3 (sycp3) and 17-alpha-hydroxylase/17,20-lyase (cyp17) genes were observed in the testes, not enough to affect testicular histology. In addition, MT at all treatments strongly increased corticotropin-releasing hormone (crh) transcript in the brain of females, as well as deiodinase 2 (dio2) transcript in the brain of males. The paired box protein 8 (pax8) gene was significantly decreased at 51 or 583 ng/L of MT in both female and male brains. The above results suggest that MT can pose potential adverse effects on the reproductive and thyroid endocrine system of fish.

Toward systematic understanding of adsorptive removal of legacy and emerging per-and polyfluoroalkyl substances (PFASs) by various activated carbons (ACs).

Per-and polyfluoroalkyl substances (PFASs) have received great attention due to their persistence, bioaccumulation and toxicity. Various activated carbons (ACs) exhibit wide variability in adsorptive performance towards PFASs. In order to gain a systematic understanding of adsorptive removal of legacy and emerging PFASs by ACs, the adsorption of ten PFASs on various ACs was comprehensively investigated. Results showed that granular activated carbon-1 (GAC-1) and powdered activated carbon-1 (PAC-1) removed more than 90% of all target PFASs. Particle size, surface charge, and micropores quantity of ACs were closely related to their performance for PFASs removal. Electrostatic interaction, hydrophobic interaction, surface complexation and hydrogen bonding were the adsorption mechanisms, with hydrophobic interaction being the predominant adsorptive force. Physical and chemical adsorption were both involved in PFAS adsorption. The removal rates of PFASs by GAC-1 decreased from 93%-100% to 15%-66% in the presence of 5 mg/L fulvic acid (FA). GAC was able to remove more PFASs under acidic medium, whereas PAC removed hydrophobic PFASs better under the neutral medium. The removal rates of PFASs by GAC-3 increased significantly from 0%-21% to 52%-97% after being impregnated with benzalkonium chlorides (BACs), demonstrating the superiority of this modification method. Overall, this study provided theoretical support for removing PFASs from water phase with ACs.

Automated µFTIR Imaging Demonstrates Taxon-Specific and Selective Uptake of Microplastic by Freshwater Invertebrates.

Microplastic particles can be deposited to sediments and subsequently ingested by benthic organisms. It is unknown to what extent ingestion of microplastic is taxon-specific or whether taxa can be selective toward certain types of microplastics. Here, we used state-of-the-art automated micro-Fourier-transform infrared (µFTIR) imaging and attenuated total reflectance FTIR spectroscopy to determine small-size (20-500 µm) and large-size (500-5000 µm) microplastic particles in sediments and a range of benthic invertebrate species sampled simultaneously from the Dommel River in the Netherlands. Microplastic number concentrations differed across taxa at the same locations, demonstrating taxon-specific uptake, whereas size distributions were the same across sediments and taxa. At the site with the highest concentration, microplastic occupied up to 4.0% of the gut volume of Asellidae. Particle shape distributions were often not statistically different between sediments and taxa, except for Astacidea at one of the locations where the proportion of particles with a length to width ratio >3 (i.e., fibers) was twice as high in sediments than in Astacidea. Acrylates/polyurethane/varnish was predominately found in sediments, while soft and rubbery polymers ethylene propylene diene monomer and polyethylene-chlorinated were the dominant polymers found in invertebrates. Microplastic polymer composition and thus polymer density differed significantly between invertebrates and their host sediment. Trophic transfer at the base of the food web appears to have a filter function with respect to microplastic particle types and shapes. Together with the very high ingestion rates, this has clear implications for ecological and human health risks, where uptake concerns edible species (e.g., Astacidea).

Distribution, partitioning behavior and potential source of legacy and alternative per- and polyfluoroalkyl substances (PFASs) in water and sediments from a subtropical Gulf, South China Sea.

Legacy per- and polyfluoroalkyl acids (PFASs) have received global concern over the scientific and public community since this century. However, the information on alternative PFASs pollution in the marine environment, especially in the subtropical marine environment is extremely limited. This study investigated the occurrence, partitioning, potential sources, and ecological risks of PFASs, including perfluoroalkane sulfonic acids (PFSAs), perfluoroalkyl carboxylic acids (PFCAs), and alternative PFASs, in surface water and sediments from the subtropical Beibu Gulf, South China. Concentrations of total PFASs (∑PFASs) were in the range of 0.98-2.64 ng/L in water and 0.19-0.66 ng/g (dry weight, dw) in sediment, respectively. Perfluorooctanoic acid (PFOA) was the most abundant PFAS in water, while PFASs in sediment were dominated by perfluorooctanesulfonic acid (PFOS) and PFOA. Among investigated environmental parameters (total organic carbon (TOC), grain size, water pH, sediment pH, and salinity), TOC and salinity were the dominant factors influencing the sediment-water distribution coefficient (Kd) of PFOA, perfluorodecanoic acid (PFDA), and perfluorononanoic acid (PFNA). Log Kd and log soil organic carbon-water distribution coefficient (Koc) both increase with increasing carbon chain length of PFASs. Significantly positive correlations between PFOS and perfluorohexanoic acid (PFHxA) (p < 0.05), PFOA and perfluoro-1-butane-sulfonamide (FBSA) were observed, suggesting that these PFASs might have similar sources and transport routes. Preliminary environmental risk assessment showed that PFOA and PFOS would not pose risks to the marine aquatic environment. This is the first comprehensive survey of legacy and alternative PFASs in a subtropical area of the Beibu Gulf, which provides significant data and scientific basis to better understand the fate of PFASs and pollution control management.

Histological and transcriptional effects of androstenedione in adult zebrafish (Danio rerio).

As a natural androgen, androstenedione (AED) may pose potential risks to aquatic organisms due to its ubiquitousness in aquatic environments. Here we assessed the adverse effects of AED on histology of gonads, as well as mRNA expression levels of 34 genes concerned with hypothalamic-pituitary-gonadal (HPG) axis, germ-cell differentiation and sex differentiation in zebrafish (Danio rerio). Adult zebrafish were exposed to solvent control and three measured concentrations of 0.2, 2.3 and 23.7 µg/L AED for 60 days. The results showed that AED did not induce any obvious histological effects in the ovaries and testes. Of the investigated genes, transcriptional expression levels of amh and cyp11c1 genes in the ovaries of females were significantly increased by AED at 2.3 or 23.7 µg/L. However, different exposure concentrations of AED significantly inhibited mRNA expression of gnrh3, atf4b1 and cyp19a1b in the brain of males. In the testes of males, AED at 2.3 µg/L led to a significant induction of sox9b gene, but it at 23.7 µg/L down-regulated nr5a1b gene. These observed transcriptional changes indicated that AED could pose potential androgenic effects in zebrafish.

Insights into the sediment toxicity of personal care products to freshwater oligochaete worms using Fourier transform infrared spectroscopy.

Personal care products (PCPs) are ubiquitous in the environment due to their wide use in daily life. However, there are insufficient sediment toxicity data of PCPs under ecologically relevant conditions. Here we used Fourier transform infrared spectroscopy (FTIR) to investigate the sediment toxicity of triclosan (TCS) and galaxolide (HHCB) to two freshwater benthic macroinvertebrates, Limnodrilus hoffmeisteri and Branchiura sowerbyi, in microcosms containing a diverse biological community. Exposure to 8 µg TCS/g and 100 µg HHCB/g dry weight (dw) sediment induced significant biochemical alterations in the L. hoffmeisteri tissue. 8 µg TCS/g primarily affected proteins and nucleic acid while 100 µg HHCB/g mainly affected proteins and lipids of L. hoffmeisteri. However, 0.8 µg TCS/g and 30 µg HHCB/g did not cause significant subcellular toxicity to L. hoffmeisteri. In contrast, exposure of B. sowerbyi to 30 µg HHCB/g led to significant biochemical changes, including proteins, polysaccharides and lipids. Therefore, B. sowerbyi was more sensitive to sediment-associated HHCB than L. hoffmeisteri. Such effects were significantly enhanced when the HHCB concentration increased to 100 µg/g dw where death of B. sowerbyi occurred. These results demonstrate the application of FTIR spectroscopy to sediment toxicity testing of chemicals to benthic invertebrates with biochemical alterations as endpoints that are more sensitive than standard toxic endpoints (e.g., survival and growth).

Fate and effects of sediment-associated polycyclic musk HHCB in subtropical freshwater microcosms.

Galaxolide (HHCB) is used as a fragrance ingredient in household and personal care products, and has been ubiquitously detected in the environment. Here we investigated the fate of HHCB in subtropical freshwater microcosms, and evaluated effects of sediment-associated HHCB on a biological community consisting of algae, Daphnia, benthic macroinvertebrates and bacteria. The concentrations of sediment-associated HHCB did not change significantly during a 28 days exposure period, but HHCB accumulated in worms with biota-sediment accumulation-factor (BSAF) values in the range of 0.29-0.66 for Branchiura sowerbyi and 0.94-2.11 for Limnodrilus hoffmeisteri. There was no significant effects of HHCB (30 µg/g dry weight (dw) sediment) on chlorophyll-a content, sediment bacterial community composition, and survival and growth of benthic macroinvertebrates. However, the presence of benthic macroinvertebrates altered the sediment bacterial community structure relative to microcosms without introduced organisms. The findings of this study suggest that a single high-dose of HHCB, over 28 days, at environmentally relevant concentrations would not impose direct toxicological risks to aquatic organisms such as benthic macroinvertebrates.

Bioaccumulation and Biotransformation of Triclosan and Galaxolide in the Freshwater Oligochaete Limnodrilus hoffmeisteri in a Water/Sediment Microcosm.

Personal care products are widely used in our daily life in considerable quantities and discharged via the down-the-drain route to aquatic environments, resulting in potential risks to aquatic organisms. We investigated bioaccumulation and biotransformation of two widely used personal care products, triclosan (TCS) and galaxolide (HHCB) spiked to sediment, in the oligochaete worm Limnodrilus hoffmeisteri in water/sediment microcosms. After 7 days of sediment exposure to 3.1 µg of TCS or HHCB/g of dry weight sediment, the accumulation of TCS and HHCB in L. hoffmeisteri reached equilibrium, at which point the biota-sediment accumulation factors (BSAFs) were 2.07 and 2.50 for TCS and HHCB, respectively. The presence of L. hoffmeisteri significantly accelerated the dissipation of the levels of TCS and HHCB in the microcosms, with approximately 9.03 and 2.90% of TCS and HHCB, respectively, eliminated from the water/sediment systems after exposure for 14 days in the presence of worms. Two biotransformation products, methyl triclosan and triclosan O-sulfate, were identified for TCS in worm tissue, whereas only methyl triclosan was identified in the sediment. Unlike TCS, no evidence of biotransformation products was found for HHCB in either worm tissue or sediment. These experiments demonstrate that L. hoffmeisteri biotransformed TCS through methylation and sulfation, whereas HHCB biotransformation was undetectable.

Triclosan-induced transcriptional and biochemical alterations in the freshwater green algae Chlamydomonas reinhardtii.

Triclosan (TCS) is an antibacterial and antifungal agent widely used in personal care products (PCPs). We investigated the effects of TCS (20µg/L, 100µg/L and 500µg/L) on Chlamydomonas reinhardtii by measuring the algal growth, chlorophyll content, lipid peroxidation, and transcription of the antioxidant-related genes (superoxide dismutase (SOD), glutathione peroxidase (GPX), catalase (CAT), glutathione S-transferase (GST), plastid terminal oxidase 2 (PTOX) and thioredoxin (TRX)) as well as biochemical alterations. The results showed significant dose-related effects of TCS on the algal species in terms of growth and chlorophyll content. Malondialdehyde (MDA) increased with increasing TCS concentrations and showed significant difference between the treatment of 405.3µg/L TCS and control group. Transcription analysis revealed that the expression of SOD mRNA was most sensitive to TCS among the selected genes. In addition, Fourier-transform infrared spectroscopy showed time- and concentration-specific biochemical responses in C. reinhardtii when exposed to TCS. The biochemical alterations associated with different doses of TCS were mainly attributed to structural changes associated with lipid, protein, nucleic acid and carbohydrate. The findings from this study reveal that TCS in the aquatic environment may affect algal growth, chlorophyll synthesis, oxidative stress responses and cause biochemical alterations. This study provided important information to achieve a better understanding of the toxic mechanism of triclosan on algae Chlamydomonas reinhardtii.

Comprehensive evaluation of antibiotics emission and fate in the river basins of China: source analysis, multimedia modeling, and linkage to bacterial resistance.

Antibiotics are widely used in humans and animals, but there is a big concern about their negative impacts on ecosystem and human health after use. So far there is a lack of information on emission inventory and environmental fate of antibiotics in China. We studied national consumption, emissions, and multimedia fate of 36 frequently detected antibiotics in China by market survey, data analysis, and level III fugacity modeling tools. Based on our survey, the total usage for the 36 chemicals was 92700 tons in 2013, an estimated 54000 tons of the antibiotics was excreted by human and animals, and eventually 53800 tons of them entered into the receiving environment following various wastewater treatments. The fugacity model successfully predicted environmental concentrations (PECs) in all 58 river basins of China, which are comparable to the reported measured environmental concentrations (MECs) available in some basins. The bacterial resistance rates in the hospitals and aquatic environments were found to be related to the PECs and antibiotic usages, especially for those antibiotics used in the most recent period. This is the first comprehensive study which demonstrates an alarming usage and emission of various antibiotics in China.

Spatial distribution of perfluoroalkyl substances in surface sediments of five major rivers in China.

Perfluoroalkyl substances (PFASs) have received great attention from the public and scientific community due to their potential adverse impacts on the ecosystem and human health. We investigated the occurrence and distribution of 16 PFASs from 2 classes of PFASs-perfluoroalkyl carboxylic acids and perfluoroalkane sulfonic acids-in the archived surface sediments of five major rivers (Yellow River, Hai River, Liao River, Zhujiang River, and Dongjiang River) in northern and southern China. The study was also performed during the wet and dry seasons. Perfluorooctanoic acid and perfluorooctane sulfonic acid were the most frequently detected (detection frequency = 100 and 63 %, respectively) in the sediments of the five rivers; the concentrations ranged from 0.08 to 0.99 ng/g dry weight (dw) and were lower than the limit of detection (

Emission estimation and multimedia fate modeling of seven steroids at the river basin scale in China.

Steroids are excreted from humans and animals and discharged with wastewaters into the environment, resulting in potential adverse effects on organisms. Based on the excretion rates from different groups of humans and animals, the emissions of seven steroids (estrone (E1), 17ß-estradiol (E2), estriol (E3), testosterone (T), androsterone (A), progesterone (P), and cortisol (C)) were comprehensively estimated in 58 river basins of whole China, and their multimedia fate was simulated by using a level III fugacity multimedia model. The results showed that higher emission densities for the steroids were found in the river basins of east China than in west China. This distribution was found to be generally similar to the distribution of Gross Domestic Product (GDP) across China. E3, A, and P displayed higher emission densities than the other steroids in most of the river basins. The total excretion of steroids by humans and animals in China was estimated to be 3069 t/yr. The excretion of steroids from animals was two times larger than that from humans. After various treatments, the total emission of steroids was reduced to 2486 t/yr, of which more than 80% was discharged into the water compartment. The predicted concentrations in water were within an order of magnitude of the measured concentrations available in the literature. Owing to wastewater irrigation, more steroid mass loadings in agricultural soil were found in the basins of Haihe River and Huaihe River in comparison with the other river basins. To the best of our knowledge, this is the first report on the emissions and multimedia fate of seven steroids in the river basins of China.

Analysis of 21 progestagens in various matrices by ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) with diverse sample pretreatment.

In this study, a highly sensitive and robust method using an ultra-high-performance liquid chromatography-tandem mass spectrometry combined with solid-phase extraction and ultrasonic extraction for pretreatment and silica gel purification steps has been developed for determination of 21 natural and synthetic progestagens in river surface water and sediments, and influents, effluents, and sludge from municipal wastewater treatment plants, and flush water and feces from swine farms. For the various matrices considered, the optimized method showed satisfactory performance with recoveries of 70-129 % (except AD, 5α-DHP, DPT, HPC), the limits of quantification below 2.30 ng/L for liquid samples and 2.59 ng/g for solid samples (except AD), and good linearity and reproducibility. This developed method was successfully applied in the analysis of progestagens in environmental samples from Liuxi Reservoir, Xintang municipal wastewater treatment plant, and Shunfeng swine farm in South China. Six analytes were detected at trace levels in surface water, effluent, and sediment samples. Seven analytes (0.7 (HPA)-35.1 ng/L (DGT)) were found in the influent samples and three analytes (5.6 (DGT)-11.8 ng/g (5α-DHP)) in the dewatered sludge samples. Moreover, 13 analytes were detected in swine farm, with high concentrations ranging from 23.8 ng/L (ET) to 5,024 ng/L (P) in flush water, and from 20.0 ng/g (MPA) to 1952 ng/g (P) in feces.

Bioaccumulation and risk assessment of per- and polyfluoroalkyl substances in wild freshwater fish from rivers in the Pearl River Delta region, South China.

Per- and polyfluoroalkyl substances (PFASs) are used in various industries, which results in their ubiquitous occurrence in the environment. This study determined the concentrations of eighteen PFASs in muscle and liver of nine wild freshwater fish species collected from rivers in the Pearl River Delta (PRD) region, South China, and assessed their bioaccumulation and potential health risks to local people. The results showed that eight and twelve PFASs were detected in the fish muscle and liver samples, respectively. Perfluorooctane sulfonate (PFOS) was found to be the predominant PFAS both in muscle and liver with its highest concentrations of 79ng/g wet weight (ww) in muscle and 1500ng/g ww in liver, followed by Perfluoroundecanoic acid (PFUnDA) and Perfluorotridecanoic acid (PFTrDA) with trace concentrations. The mean PFOS concentrations in fish muscle and liver tissues of the nine collected species ranged from 0.40ng/g in mud carp to 25ng/g in snakehead, and from 5.6ng/g in mud carp to 1100ng/g in snakehead, respectively. Significant positive correlations were found among PFASs both in water and fish, indicating a similar pollution source for these PFASs. In tilapia samples, PFOS concentrations showed an increasing trend with increasing length and weight, but no significant difference between genders. Bioaccumulation factors (logBAF) in fish for the PFASs were in the range from 2.1 to 5.0. The calculated hazard ratios (HR) of PFOS for all fishes were in the range of 0.05-2.8, with four out of nine species (tilapia, chub, leather catfish and snakehead) having their HR values more than 1.0. The results suggest that frequent consumption of these four fish species may pose health risks to local population.

Simultaneous determination of trace marine lipophilic and hydrophilic phycotoxins in various environmental and biota matrices.

An efficient and sensitivity approach, which combines solid-phase extraction or ultrasonic extraction for pretreatment, followed by ultra-performance liquid chromatography-tandem mass spectrometry, has been established to simultaneously determine eight lipophilic phycotoxins and one hydrophilic phycotoxin in seawater, sediment and biota samples. The recoveries and matrix effects of target analytes were in the range of 61.6-117.3 %, 55.7-121.3 %, 57.5-139.9 % and 82.6 %-95.0 %, 85.8-106.8 %, 80.7 %-103.3 % in seawater, sediment, and biota samples, respectively. This established method revealed that seven, six and six phycotoxins were respectively detected in the Beibu Gulf, with concentrations ranging from 0.14 ng/L (okadaic acid, OA) to 26.83 ng/L (domoic acid, DA) in seawater, 0.04 ng/g (gymnodimine-A, GYM-A) to 2.75 ng/g (DA) in sediment and 0.01 ng/g (GYM-A) to 2.64 ng/g (domoic acid) in biota samples. These results suggest that the presented method is applicable for the simultaneous determination of trace marine lipophilic and hydrophilic phycotoxins in real samples.

Rapid adsorptive removal of emerging and legacy per- and polyfluoroalkyl substances (PFASs) from water using zinc chloride-modified litchi seed-derived biochar.

The present study successfully synthesized a novel biochar adsorbent (M-L-BC) using litchi seed modified with zinc chloride for PFASs removal in water. M-L-BC greatly enhanced removal of all examined PFASs (>95 %) as compared to the pristine biochar (<40 %). The maximum adsorption capacity was observed for PFOS, reaching 29.6 mg/g. Adsorption kinetics of PFASs followed the pseudo-second-order model (PSO), suggesting the predominance of chemical adsorption. Moreover, characterization and density functional theory (DFT) calculations jointly revealed involvement of surface complexation, electrostatic interactions, hydrogen bonding, and hydrophobic interactions in PFAS adsorption. Robust PFAS removal was demonstrated for M-L-BC across a wide range of pH (3-9), and coexisting ions had limited impact on adsorption of PFASs except PFBA. Furthermore, M-L-BC showed excellent performance in real water samples and retained reusability after five cycles of regeneration. Overall, M-L-BC represents a promising and high-quality adsorbent for efficient and sustainable removal of PFASs from water.

The impact of co-exposure to polystyrene microplastics and norethindrone on gill histology, antioxidant capacity, reproductive system, and gut microbiota in zebrafish (Danio rerio).

In recent years, studies have focused on the combined ecological risks posed by microplastics and other organic pollutants. Although both microplastics and progestin residues are frequently detected in the aquatic environments, their ecological implications remain unknown. Adult zebrafish were exposed to polystyrene microplastics (PS, 200 nm, 200 µg/L), norethindrone (NET, 69.6 ng/L), and their mixture (200 µg/L PS + 63.1 ng/L NET) for 30 days. The results demonstrated that exposure to PS and NET resulted in gill damage. Notably, the PS and PS+NET exhibited a significant decrease in glutathione (GSH) and oxidized glutathione (GSSG) content, as well as reduced antioxidase activity in the gills. The oxidative stress in PS+NET primarily originated from PS. The PS, NET, or their mixture resulted in a decrease in testosterone (T) and estradiol (E2) levels in female. Furthermore, compared to NET, the PS+NET showed a significant reduction in E2 levels, thereby augmenting the inhibitory effect on reproductive ability mediated by NET. However, males showed an increase in 11-ketodihydrotestosterone (11-KT) content, accompanied by a significant decrease in spermatogonia (Sg) and increase in spermatocytes (Sc). Consequently, it can be inferred that PS enhances the androgenic effect of NET. In female fish brain, NET alone resulted in transcriptional down-regulation of partial hormone receptors; however, co-administration of PS effectively mitigated the interference effects. Furthermore, transcriptional downregulation of 17-alpha-hydroxylase (cyp17), hydroxysteroid 3-beta dehydrogenase (hsd3b), estrogen receptor 1 (esr1), and estrogen receptor 2a (esr2b) genes in the ovary was found to be associated with the androgenic activity induced by NET. Moreover, in comparison to PS or NET alone, PS+NET resulted in a notable decrease in Cetobacterium abundance and an increase in Aeromonas population, suggesting that the co-exposure of PS+NET may exacerbate intestinal burden. The findings highlight the importance of studying the combined toxicity of PS and NET.

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

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

Insights into the Understanding of Adsorption Behaviors of Legacy and Emerging Per- and Polyfluoroalkyl Substances (PFASs) on Various Anion-Exchange Resins.

Per- and polyfluoroalkyl substances (PFASs) have received extensive attention due to their various harmful effects. In this study, the adsorptive removal of 10 legacy and emerging PFASs by four anion-exchange resins (including gel and macroreticular resins) were systematically investigated. Our results showed that the capacities of resins absorbing PFASs were ranked in the following order: gel strong base HPR4700 (297~300 µg/g) ≈ macroreticular strong base S6368 (294~300 µg/g) ≈ macroreticular weak base A111S (289~300 µg/g) > gel weak base WA10 (233~297 µg/g). Adsorption kinetic results indicated that the adsorption process might involve chemical and Henry regime adsorption or reaction control. Intraparticle diffusion was probably the major removal step. Co-existing fulvic acid (0.5, 1, 5 mg/L) and inorganic anions (5 mg/L of sulfate, carbonate, bicarbonate) would hinder the PFAS removal by resins with WA10 showing the highest inhibition rate of 17% and 71%, respectively. The adsorption capacities of PFBA decreased from 233 µg/g to 194 µg/g, and from 233 µg/g to 67 µg/g in the presence of fulvic acid and inorganic anions, respectively. PFASs were more easily removed by HPR4700, S6368, and A111S under neutral and alkaline environment. Moreover, WA10 was not able to remove PFASs under an alkaline medium. This study offered theoretical support for removing PFASs from aqueous phases with various resins.

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

The widespread use of antibiotics has raised global concerns, but scarce information on antibiotics in the subtropical marine environment is available. In the present study, seawater and sediment samples were collected to investigate the occurrence, spatial distribution, source, and ecological risks of 22 antibiotics in the Beibu Gulf. The total concentrations of target antibiotics (∑antibiotics) were in the range of 1.74 ng/L to 23.83 ng/L for seawater and 1.33 ng/g to 8.55 ng/g dry weight (dw) for sediment. Spatially, a decreasing trend of antibiotic levels from coast to offshore area was observed, with relatively high levels at the sites close to the Qinzhou Bay and Qiongzhou Strait. Sulfamethoxazole (SMX), trimethoprim (TMP), and norfloxacin (NOX) were predominant in seawater, while NOX, enoxacin (ENX), and enrofloxacin (ENR) were the most abundant antibiotics in sediment. In general, the sediment-water partitioning coefficients (Kd) were positively correlated with log molecular weight (MW). Salinity, particle size, and pH of water were predicted to be vital factors influencing the partition of sulfadiazine (SDZ), CIX, and ENR (p < 0.05). Livestock and aquaculture were identified as dominant sources of antibiotics in the Beibu Gulf based on PCA-MLR and Unmix model. Risk assessment revealed that SMX, CIX could pose medium risks to algae in the Beibu Gulf. Overall, our results provided paramount insights into understanding the fate and transport behaviors of antibiotics in the subtropical marine environment.