Search

Abstract Potential effects of horizontal drilling combined with high-volume hydraulic fracturing (HF) have drawn significant public concern, especially on the handling, treatment, and disposal of HF flowback and produced water (HF-FPW). Previous studies indicated HF-FPW could significantly disrupt biotransformation and expressions of genes related to the endocrine system. This study focused on effects of organic extracts of HF-FPW on receptor binding activity using several transactivation assays. Six HF-FPW samples were collected from 2 wells (Well A and Well B, 3 time points at each well). These were separated by filtration into aqueous (W) and particulate (S) phases, and organics were extracted from all 12 subsamples. Of all the tested fractions, sample B1-S had the greatest Σ 13 PAH (11,000 ng/L) and B3-S has the greatest Σ 4 alkyl-PAHs (16,000 ng/L). Nuclear receptor binding activity of all the extracts on aryl hydrocarbon receptor (AhR), estrogen receptor (ER), and androgen receptor (AR) were screened using H4IIE- luc , MVLN- luc , and MDA-kb2 cells, respectively. FPWs from various HF wells exhibited distinct nuclear receptor binding effects. The strongest AhR agonist activity was detected in B3-S, with 450 ± 20 μg BaP/L equivalency at 5 × exposure. The greatest ER agonist activity was detected in A1-W, with 5.3 ± 0.9 nM E2 equivalency at 10× exposures. There is a decreasing trend in ER agonist activity from A1 to A3 in both aqueous and particulate fractions from Well A, while there is an increasing trend in ER agonist activity from B1 to B3 in aqueous fractions from Well B. This study provides novel information on the sources of endocrine disruptive potentials in various HF-FPW considering both temporal and spatial variability. Results suggest that reclamation or remediation and risk assessment of HF-FPW spills likely requires multiple strategies including understanding the properties of each spill with respect to fractured geological formation and physiochemical properties of the injected fluid. Graphical abstract Unlabelled Image Highlights • HF-FPWs possess distinct PAH profiles and toxicities that differ by wellsite • HF-FPWs have distinct temporal trends in PAH profiles and toxicities • Organic extracts of HF-FPW have disrupting effects on nuclear receptors binding [ABSTRACT FROM AUTHOR]

Hydraulic fracturing to extract oil and natural gas reserves is an increasing practice in many international energy sectors. Hydraulic fracturing flowback and produced water (FPW) is a hyper saline wastewater returned to the surface from a fractured well containing chemical species present in the initial fracturing fluid, geogenic contaminants, and potentially newly synthesized chemicals formed in the fracturing well environment. However, information on FPW toxicological mechanisms of action remain largely unknown. Both cardiotoxic and respirometric responses were explored in zebrafish ( Danio rerio ) embryos after either an acute sediment-free (FPW-SF) or raw/sediment containing (FPW-S) fraction exposure of 24 and 48 h at 2.5% and 5% dilutions. A 48 h exposure to either FPW fraction in 24–72 h post fertilization zebrafish embryos significantly increased occurrences of pericardial edema, yolk-sac edema, and tail/spine curvature. In contrast, larval heart rates significantly decreased after FPW fraction exposures. FPW-S, but not FPW-SF, at 2.5% doses significantly reduced embryonic respiration/metabolic rates (MO 2 ), while for 5% FPW, both fractions reduced MO 2 . Expression of select cardiac genes were also significantly altered in each FPW exposure group, implicating a cardiovascular system compromise as the potential cause for reduced embryonic MO 2 . Collectively, these results support our hypothesis that organics are major contributors to cardiac and respiratory responses to FPW exposure in zebrafish embryos. Our study is the first to investigate cardiac and respiratory sub-lethal effects of FPW exposure, demonstrating that FPW effects extend beyond initial osmotic stressors and verifies the use of respirometry as a potential marker for FPW exposure. [ABSTRACT FROM AUTHOR]

Hydraulic fracturing (HF) has emerged as a major method of unconventional oil and gas recovery. The toxicity of hydraulic fracturing flowback and produced water (HF-FPW) has not been previously reported and is complicated by the combined complexity of organic and inorganic constituents in HF fluids and deep formation water. In this study, we characterized the solids, salts, and organic signatures in an HF-FPW sample from the Duvernay Formation, Alberta, Canada. Untargeted HPLC-Orbitrap revealed numerous unknown dissolved polar organics. Among the most prominent peaks, a substituted tri-phenyl phosphate was identified which is likely an oxidation product of a common polymer antioxidant. Acute toxicity of zebrafish embryo was attributable to high salinity and organic contaminants in HF-FPW with LC50 values ranging from 0.6% to 3.9%, depending on the HF-FPW fractions and embryo developmental stages. Induction of ethoxyresorufin-O-deethylase (EROD) activity was detected, due in part to polycyclic aromatic hydrocarbons (PAHs), and suspended solids might have a synergistic effect on EROD induction. This study demonstrates that toxicological profiling of real HF-FPW sample presents great challenges for assessing the potential risks and impacts posed by HF-FPW spills. [ABSTRACT FROM AUTHOR]

Biochars have increasingly been used as adsorbents for organic and inorganic contaminants in soils. However, during the carbonization process of pyrolysis, contaminants, including polycyclic aromatic hydrocarbons (PAHs) and polychlorinated dioxins and furans (PCDD/DF) can be generated. In this study, biochars made from sawdust, were prepared at various temperatures ranging from 250 to 700 °C. The Microtox ® and rat hepatoma cell line H4IIE- luc assays were used to characterize the general toxic and effects, mediated through the aryl hydrocarbon receptor (AhR), or dioxin-like potencies of organic extracts of biochars. The greatest total concentrations of PAHs (8.6 × 10 2 μg kg −1 ) and PCDD/DF (6.1 × 10 2 pg g −1 ) were found in biochar generated at 400 °C and 300 °C, respectively. Results of the H4IIE- luc assay, which gives total concentrations of 2,3,7,8-TCDD equivalents (TEQ H4IIE- luc ), indicated that total potencies of aryl hydrocarbon receptor (AhR) agonists were in decreasing order: 300 °C > 250 °C > 400 °C > 500 °C > 700 °C. The 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQ chem ) calculated as the sum of products of 16 PAHs and 17 PCDD/DF congers multiplied by their respective relative potencies (RePs) was less than that of TEQ H4IIE- luc determined by use of the bioanalytical method, with the H4IIE- luc assay, which measures the total dioxin-like potency of a mixtures. The ratio of TEQ chem /TEQ H4IIE- luc was in the range of 0.7%–3.8%. Thus, a rather small proportion of the AhR-mediated potencies extracted from biochars were identified by instrumental analyses. Results of the Microtox test showed similar tendencies as those of the H4IIE- luc test, and a linear correlation between EC50 of Microtox test and EC20 of H4IIE- luc test was found. The results demonstrated that biochars produced at higher pyrolysis temperatures (>400 °C) were less toxic and had lower potencies of AhR-mediated effects, which may be more suitable for soil application. [ABSTRACT FROM AUTHOR]

The beta-blocker atenolol (ATE), and the selective serotonin and norepinephrine reuptake inhibitor, venlafaxine (VEN) are frequently detected in municipal wastewater effluents, but little is known about their ecotoxicological effect on aquatic animals. Herein, ATE and VEN were selected to explore their accumulation and global DNA methylation (GDM) in zebrafish tissues after a 30-day exposure. Molecular dynamics (MD) stimulation was used to investigate the toxic mechanism of ATE and VEN exposure. The results demonstrated that ATE and VEN could reduce the condition factor of zebrafish. The bioaccumulation capacity for ATE and VEN was in the order of liver > gut > gill > brain and liver > gut > brain > gill, respectively. After a 30-day recovery, ATE and VEN could still be detected in zebrafish tissues when exposure concentrations were ≥10 μg/L. Moreover, ATE and VEN induced global DNA hypomethylation in different tissues with a dose-dependent manner and their main target tissues were liver and brain. When the exposure concentrations of ATE and VEN were increased to 100 μg/L, the global DNA hypomethylation of liver and brain were reduced to 27% and 18%, respectively. In the same tissue exposed to the same concentration, DNA hypomethylation induced by VEN was more serious than that of ATE. After a 30-day recovery, the global DNA hypomethylations caused by the two drugs were still persistent, and the recovery of VEN was slower than that of ATE. The MD simulation results showed that both ATE and VEN could reduce the catalytic activity of DNA Methyltransferase 1 (DNMT1), while the effect of VEN on the 3D conformational changes of the DNMT1 domain was more significant, resulting in a lower DNA methylation rate. The current study shed new light on the toxic mechanism and potential adverse impacts of ATE and VEN on zebrafish, providing essential information to the further ecotoxicological risk assessment of these drugs in the aquatic environment. [Display omitted] • ATE and VEN exposure decreased body weight and condition factor of zebrafish. • Liver has the highest bioaccumulation capacities of the two drugs. • Drug residues could be detected after 30- days' recovery from exposure. • ATE- and VEN-induced DNA hypomethylation were dose-dependent and tissue-specific. • Induced conformation changes by drugs reduced the catalytic ability of DNMT1. [ABSTRACT FROM AUTHOR]

Abstract: Oil sands process-affected water (OSPW) is produced by the oil sands industry in Alberta, Canada. OSPW has acute and chronic effects on aquatic organisms, but the suite of effects of OSPW, and mechanisms of effects, are not understood. The goal of this study was to use RNA sequencing (RNAseq) to quantify abundances of transcripts in livers of male fathead minnows exposed to untreated OSPW and ozone-treated OSPW to investigate sublethal effects of untreated OSPW and to determine whether ozonation imparts toxicity upon OSPW. A reference transcriptome of 25,342 contigs was constructed from RNA from livers of fathead minnows exposed to various experimental conditions. Exposure to untreated OSPW resulted in greater abundances of 104 transcripts and lesser abundances of 91 transcripts. Oxidative metabolism, oxidative stress, apoptosis, and immune function were identified as processes affected by OSPW. Exposure to ozone-treated OSPW resulted in greater abundances of 57 transcripts and lesser abundances of 75 transcripts. However, in general, putative pathways for effects of OSPW in fathead minnows exposed to untreated OSPW were not identified in minnows exposed to ozone-treated OSPW, and pathways by which ozone-treated OSPW might have effects were not identified. [Copyright &y& Elsevier]

Abstract: Due to a policy of no release, oil sands process-affected water (OSPW), produced by the surface-mining oil sands industry in North Eastern Alberta, Canada, is stored on-site in tailings ponds. Currently, ozonation is considered one possible method for remediation of OSPW by reducing the concentrations of dissolved organic compounds, including naphthenic acids (NAs), which are considered the primary toxic constituents. However, further work was needed to evaluate the effectiveness of ozonation in reducing the toxicity of OSPW and to ensure that ozonation does not increase the toxicity of OSPW. This study examined effects of untreated, ozone-treated, and activated charcoal-treated OSPW (OSPW, O3-OSPW, and AC-OSPW) on the early life stage (ELS) of fathead minnow (Pimephales promelas). Success of hatching of eggs, spontaneous movement, and incidences of hemorrhage, pericardial edema, and malformation of the spine of embryos were examined. To elucidate the mechanism of toxicity, concentrations of reactive oxygen species (ROS) were measured, and the abundances of transcripts of genes involved in biotransformation of xenobiotics, response to oxidative stress, and apoptosis were quantified by real-time PCR. Compared to the control group, which had an embryo survival rate of 97.9 ± 2.08%, survival was significantly less when exposed to OSPW (43.8 ± 7.12%). Eggs exposed to untreated OSPW exhibited a significantly greater rate of premature hatching, and embryos exhibited greater spontaneous movement. Incidences of hemorrhage (50.0 ± 3.40%), pericardial edema (56.3 ± 7.12%), and malformation of the spine (37.5 ± 5.38%) were significantly greater in embryos exposed to OSPW compared to controls. These effects are typical of exposure to dioxin-like compounds, however, abundance of transcripts of cyp1a was not significantly greater in embryos exposed to OSPW. Significantly greater concentrations of ROS, and greater abundances of transcripts cyp3a, gst, sod, casp9, and apopen compared to controls, indicated that exposure to OSPW caused oxidative stress, which can result in damage to mitochondria and promote activation of caspase enzymes and apoptotic cell death. Removal of dissolved organic constituents by ozone treatment, or by activated charcoal, significantly attenuated all of the adverse effects associated with untreated OSPW. The results suggest that the organic fraction of OSPW can negatively impact the development of fathead minnow embryos through oxidative stress and apoptosis, and that ozonation attenuates this developmental toxicity. [Copyright &y& Elsevier]

Abstract: There is concern regarding oil sands process water (OSPW) produced by the oil sands industry in Alberta, Canada. Little is known about the potential for OSPW, and naphthenic acids (NAs), which are the primary persistent and toxic constituents of OSPW, to affect endocrine systems. Although ozonation significantly reduces concentrations of NAs and OSPW toxicity, it was hypothesized that oxidation of OSPW might produce hydroxylated products with steroidogenic activity. Therefore, untreated and ozone treated OSPW were examined for effects on sex steroid production using the H295R Steroidogenesis Assay. Untreated OSPW significantly decreased testosterone (T) and increased 17β-estradiol (E2) concentrations at OSPW dilutions greater or equal to 10-fold. This effect was mainly due to decreased E2 metabolism. Analysis of CYP19A (aromatase) mRNA abundance and enzyme activity suggested that induction of this enzyme activity may have also contributed to these effects. Reduction of parent NA concentrations by 24% or 85% decreased the effect of OSPW on E2 production. Although T production remained significantly reduced in cells exposed to ozone treated OSPW, the effect was diminished. Aromatase mRNA abundance and enzyme activity were significantly greater in cells exposed to ozone treated OSPW, however the magnitude was less than in cells exposed to untreated OSPW. No change of E2 metabolism was observed in cells exposed to ozone treated OSPW, which may account for recovery of E2 levels. The results indicate that OSPW exposure can decrease E2 and T production, but ozonation is an effective treatment to reduce NA concentrations in OSPW without increasing affects on steroidogenesis. [Copyright &y& Elsevier]

Abstract: Polybrominated diphenyl ethers (PBDEs) and tetrabromobisphenol A (TBBPA) are brominated flame retardants that are produced in large quantities and are commonly used in construction materials, textiles, and as polymers in electronic equipment. Environmental and human levels of PBDEs have been increasing in the past 30 years, but the toxicity of PBDEs is not fully understood. Studies on their effects are relatively limited, and show that PBDEs are neurotoxins and potential endocrine disrupters. Hydroxylated (OHhoxylated (MeOave also been reported in the adipose tissue, blood and milk of wild animals and humans. In the present study, 15 PBDE metabolites, two BDE mixtures (DE71 and DE79), and TBBPA were studied individually to determine their effects on ten steroidogenic genes, aromatase activity, and concentrations of two steroid hormones (testosterone and 17β-estradiol) in the H295R human adrenocortical carcinoma cell line. Exposure to 0.05μM 2′-OH-BDE-68 significantly induced the expression of CYP11A, CYP11B2, CYP17, CYP21, 3βHSD2, 17βHSD1, and 17βHSD4, and the expression of StAR was induced by 6-OH-BDE-90 at the three exposure concentrations. Exposure to DE71 and DE79 resulted in dose-dependent trend towards induction, but these effects were not significant. Exposure to 0.5μM 2-OH-BDE-123 and 2-MeO-BDE-123 resulted in significantly greater aromatase activity. However, none of the compounds affected sex hormone production at the concentrations tested. Generally, OH-BDEs had a much stronger ability to affect steroidogenic gene expression than MeO-BDEs. [Copyright &y& Elsevier]

Abstract: Polybrominated diphenyl ethers (PBDEs) are additive flame retardants that have been found in the environment as well as human tissues. Environmental concentrations of these compounds have been increasing in many parts of the world in recent years. Due to their structural similarity, PBDEs are believed to have similar toxicity to PCBs, but their toxicological properties are still being determined. In this study, the steroidogenic effects of hydroxylated, methoxylated and/or chlorinated derivatives of PBDEs were assessed at both the gene and enzyme/hormone levels in the H295R human adrenocortical carcinoma cell line. The expression levels of 10 steroidogenic genes were measured using quantitative real-time PCR (Q-RT-PCR). Aromatase activity in the cells and sex steroid (testosterone (T) and 17β-estradiol (E2)) concentrations in the culture medium were also measured. CYP11B2, which regulates the synthesis of aldosterone, was the most sensitive gene and was induced by most of the compounds tested in this study. CYP19 gene expression, aromatase activity, and E2 production were also affected by several metabolites, but no consistent relationship was observed between these endpoints. Several PBDE metabolites showed some potential ability to interfere with steroidogenesis, including 5-Cl-6-OH-BDE-47, a biologically relevant BDE-47 metabolite, which significantly decreased aromatase activity and E2 production at a concentration of 10μM. The results of this study indicate that PBDE metabolites affect steroidogenesis in vitro and that they may have the potential to affect steroidogenesis and reproduction in whole organisms. [Copyright &y& Elsevier]

Hydraulic fracturing flowback and produced water (HF-FPW), which contains polyaromatic hydrocarbons (PAHs) and numerous other potential contaminants, is a complex wastewater produced during the recovery of tight hydrocarbon resources. Previous studies on HF-FPW have demonstrated various toxicological responses of aquatic organisms as consequences of combined exposure to high salinity, dissolved organic compounds and particle/suspended solids-bound pollutants. Noteworthy is the lack of studies illustrating the potentially toxic effects of the FPW suspended solids (FPW-SS). In this study, we investigated the acute and sublethal toxicity of suspended solids filtered from six authentic FPW sample collected from two fracturing wells, using a sediment contact assay based on early-life stages of zebrafish (Danio rerio). PAHs profiles and acute toxicity tests provided initial information on the toxic potency of the six samples. Upon exposure to sediment mixture at two selected doses (1.6 and 3.1 mg/mL), results showed adverse effects in larval zebrafish, as revealed by increased Ethoxyresorufin-O-deethylase (EROD) activity. Transcriptional alterations were also observed in xenobiotic biotransformation (ahr , pxr , cyp1a , cyp1b1 , cyp1c1 , cyp1c2 , cyp3a65 , udpgt1a1 , udpgt5g1), antioxidant response (sod1 , sod2 , gpx1a , gpx1b) and hormone receptor signaling (esr1 , esr2a , cyp19a1a , vtg1) genes. The results demonstrated that even separated from the complex aqueous FPW mixture, FPW-SS can induce toxicological responses in aquatic organisms' early life stages. Since FPW-SS could sediment to the bottom of natural wetland acting as a continuous source of contaminants, the current findings imply the likelihood of long-term environmental risks of polluted sediments on aquatic ecosystems due to FPW spills. [Display omitted] • Flowback and produced water (FPW) suspended solids (SS) displayed toxicity on zebrafish embryo. • Low molecular weight polyaromatic hydrocarbons (PAHs) dominated the PAHs contents in FPW-SS. • EROD activities caused by FPW-SS were consistent with the trend of PAHs contents. • FPW-SS impaired biotransformation and antioxidant gene expression in zebrafish embryo. • FPW-SS disrupted gene expression on hormone receptor signaling in zebrafish embryo. [ABSTRACT FROM AUTHOR]

Hydraulic fracturing flowback and produced water (FPW) is a wastewater produced during fracturing activities in an operating well which is hyper saline and chemically heterogeneous in nature, containing both anthropogenic and petrogenic chemicals. Determination of FPW associated toxicity to embryonic fish is limited, while investigation into how embryonic exposures may affect later life stages is not yet studied. Zebrafish embryos (24 hrs post fertilization) were acutely exposed to 2.5% and 5% FPW fractions for either 24 or 48 hrs and returned to freshwater. After either 24 or 48 h exposures, embryos were examined for expression of 3 hypoxia related genes. Erythropoietin ( epoa ) but not hypoxia inducible factor ( hif1aa ) nor hemoglobin −ß chain ( hbbe1.1 ) was up-regulated after either 24 or 48 h FPW exposure. Surviving embryos were placed in freshwater and grown to a juvenile stage (60 days post fertilization). Previously exposed zebrafish were analyzed for both swim performance ( U crit and U max ) and aerobic capacity. Fish exposed to both sediment containing (FPW-S) or sediment free (FPW-SF) FPW displayed significantly reduced aerobic scope and U crit / U max values compared to control conditions. Our results collectively suggest that organics present in our FPW sample may be responsible for sub-lethal fitness and metabolic responses. We provide evidence supporting the theory that the cardio-respiratory system is impacted by FPW exposure. This is the first known research associating embryonic FPW exposures to sub-lethal performance related responses in later life fish stages. [ABSTRACT FROM AUTHOR]

[Display omitted] • Bifunctional NiReO x /Beta efficiently catalyzes the synthesis of etheric ester, with 99% conversion of ethyl levulinate and ethyl-4-ethoxy pentanoate yield about 83% at 160 °C. • ReO x enhances the hydrogenation activity of Ni nanoparticles. • Attained Bronsted acid sites on Beta contribute to the etherification. Biomass derived etheric ester compounds show promising applications as renewable fuel additives and solvents. In this study, we reported the preparation of bifunctional transition metal/zeolite catalysts comprising Ni-Re bimetal nanoparticles and Beta zeolites prepared via conventional wet-impregnation method. The bifunctional nature makes it possible for the synthesis of ethyl-4-ethoxy pentanoate (EEP) as etheric ester starting from ethyl levulinate (EL) in presence of H 2 with good performance. The textural properties and acidity of the catalysts were characterized by several techniques: XRD, TEM, STEM-Mapping, H 2 -TPR and XPS. The addition of ReO x increased the dispersion and reducibility of NiO·NH 3 -TPD and in-situ FT-IR of pyridine adsorption confirmed that the NiReO x /Beta catalyst affords large amount of Lewis acid sites and certain amount of Bronsted acid sites. The attained Bronsted acid sites in BEA topology may be the key sites contributing to the etherification. Under optimized reaction conditions, namely 160 °C, 1 MPa H 2 and reaction time of 2 h, almost full conversion of EL with 83% yield of EEP could be achieved in ethanol. [ABSTRACT FROM AUTHOR]

[Display omitted] • Conductive materials enhance electron transfer for methane production. • Properties of conductive materials promoting methane production are summarized. • Carbon, iron, and polymer-based materials can be applied in anaerobic bioreactors. • DIET theory employed for different types of substrates are discussed. Organic compounds in wastewater have a high potential to be converted to (bio)methane (CH 4) via anaerobic processes for energy recovery. Facilitating direct interspecies electron transfer (DIET) between microorganisms with the addition of conductive materials, as opposed to the conventional anaerobic biological process, has been viewed as an efficient strategy for boosting the efficiency of CH 4 production. In recent years, extensive research has been conducted on the performance, mechanisms, and technical uses of conductive materials, such as carbon, iron and polymer-based materials in anaerobic wastewater treatment systems. In this review, the properties of conductive materials have been comprehensively reviewed and summarized, along with their application strategies to enhance CH 4 production. In addition, the paper focuses on the methane production mechanism in anaerobic bioreactors, in the presence of carbon, iron, and polymer-based materials. The DIET theory employed for methane synthesis and the involvement of various organic wastes including ethanol, butyrate, propionate, and complex organic compounds are also elaborated upon. The prospective future research directions were also identified and stated in this review. [ABSTRACT FROM AUTHOR]

Micro/nanoplastics can act as vectors for organic pollutants and enhance their toxicity, which has been attributed to the ingestion by organisms and the "Trojan horse effect". In this study, we disclosed a non-ingestion pathway for the toxicity enhancement effect of nanoplastics. Initially, the combined toxicity of polystyrene microplastics (40 μm) or nanoplastics (50 nm) with three disinfection byproducts (DBPs) to a marine polychaete, Platynereis dumerilii , was investigated. No toxic effect was observed for the micro/nanoplastics alone. The microplastics showed no effect on the toxicity of the three DBPs, whereas the nanoplastics significantly enhanced the toxicity of two aromatic DBPs when the polychaete was in its non-feeding early life stage throughout the exposure period. The microplastics showed no interaction with the P. dumerilii embryos, whereas the nanoplastics agglomerated strongly on the embryonic chorion and fully encapsulated the embryos. This could contribute to higher actual exposure concentrations in the microenvironment around the embryos, as the concentrations of the two aromatic DBPs on the nanoplastics were 1200 and 120 times higher than those in bulk solution. Our findings highlight an important and previously overlooked mechanism by which nanoplastics and organic pollutants, such as DBPs, pose a higher risk to marine species at their vulnerable early life stages. This study may contribute to a broader understanding of the environmental impacts of plastic pollution and underscore the necessity to mitigate their risks associated with DBPs. [Display omitted] • Micro/nanoplastics showed no developmental toxicity on the marine polychaete. • Nanoplastics enhanced the toxicity of DBPs on organisms at the non-feeding stage. • The bioaccumulation of DBPs was enhanced by nanoplastics. • A non-ingestion exposure pathway of DBPs by nanoplastics was proposed. [ABSTRACT FROM AUTHOR]

• A significant correlation between δ15N and δ13C of SPE-DOM was observed in the YRE. • CHON with more N atoms was more aromatic and less saturated in the YRE. • CHON with fewer N atoms was more bioavailable than those with more N atoms. • CHON with fewer N atoms was transferred into those with more N atoms in the YRE. Estuaries are hotspots where terrestrially originated dissolved organic matter (DOM) is modified in molecular composition before entering marine environments. However, very few research has considered nitrogen (N) modifications of DOM molecules in estuaries, limiting our understanding of dissolved organic nitrogen (DON) cycling and the associated carbon cycling in estuaries. This study integrated optical, stable isotopes (δ15N and δ13C) and molecular composition (FT-ICR MS) to characterize the transformation of DOM in the Yangtze River Estuary. Both concentration of dissolved organic carbon (DOC) and DON decreased with increasing salinity, while their δ13C and δ15N increased with the increasing salinity. A significant positive correlation was found between δ15N and δ13C during the transportation of DOM to marginal seas, indicating that the behavior of both DOC and DON are primarily controlled by the mixing of freshwater and the seawater in the YRE. During the mixing process, the DON addition was observed using the conservative mixing curves. In the view of molecular composition, DOM molecules became more aromatic as the number of N atoms increased. Spearman correlations reveal that DOM molecules with fewer N atoms exhibited a higher enrichment in protein-like components, while those with more N atoms were more enriched in humic-like components. In addition, the δ15N and δ13C tended to increase as the N content of DOM decreased. Therefore, DON molecules with fewer N atoms were likely to be transformed into those with more N atoms based on the isotopic fractionation theory. This study establishes a linkage between the molecular composition and the δ15N of DOM, and discovers the N transformation pattern within DOM molecules during the transportation to marginal seas. [Display omitted] [ABSTRACT FROM AUTHOR]

• In total 14 LCMs were found in municipal wastewater and sludges. • 3OCB and EPhEMOB were the predominant LCMs in sewage and sludge samples. • LCMs with higher log K ow tended to show higher K d solid-water coefficients. • LCMs in wastewater were mainly removed by sorption (58.4 %) and degradation (25.4 %). • Total LCMs emission from Hong Kong population was estimated to be 3.04 kg/year. Liquid crystal monomers (LCMs), the essential substances used in the display screen of electronic devices, have been proposed as a class of emerging chemicals of concern. Despite their detection in various environmental matrices, little is known about the presence of LCMs in municipal sewage systems. This study aimed to investigate the occurrence, distribution, and fate of 64 LCMs released into the aqueous environment from a municipal wastewater treatment plant (WWTP) in Hong Kong, China. In total 14 LCMs were detected in WWTP samples. Specifically, the Σ 14 LCMs concentrations in crude influent, final effluent, and final sludge were found to be 16.8 ± 0.3 ng/L, 2.71 ± 0.05 ng/L, and 19.2 ± 1.0 ng/g dry weight, respectively. Among them, 10 fluorinated LCMs (F-LCMs) were determined to be present at concentrations of 8.90 ± 0.10 ng/L, 1.69 ± 0.05 ng/L, and 9.94 ± 1.00 ng/g dry weight, respectively. The predominant non-fluorinated LCMs (NF-LCMs) detected in all samples were 3OCB and EPhEMOB, while 2OdF3B was the dominant F-LCM. The overall removal rate of total LCMs was 83.8 ± 0.3 %, with 25.4 ± 4.8 % being removed by biodegradation and UV treatment. Compared to NF-LCMs, F-LCMs were more resistant to biodegradation. Despite the significant removal of LCMs through WWTP, the remaining LCMs in final effluent could result in an annual emission of 3.04 kg of total LCMs from the population of Hong Kong. This study provides the first evidence of LCMs contamination in municipal wastewater, possibly arising from routine electronic devices usage. Further investigation is needed to elucidate the potential impact of LCMs emission via WWTP effluent on the aquatic receiving ecosystem. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Eight LCMs were detected in the indoor dust environment for the first time. • LCMs levels were higher in the VACF dust than in homogenized indoor dust. • LCMs pollution in VACF dust was associated with various indoor characteristics. • Exposure to single and LCMs mixture induced oxidative stress in human lung cells. • NF-LCMs in indoor environments should be given more attention in the future. Indoor dust contaminated with liquid crystal monomers (LCMs) released from various commercial liquid crystal display (LCD) screens may pose environmental health risks to humans. This study aimed to investigate the occurrence of 64 LCMs in ventilation and air conditioning filters (VACF) dust, characterize their composition profiles, potential sources, and associations with indoor characteristics, and assess their in vitro toxicity using the human lung bronchial epithelial cells (BEAS-2B). A total of 31 LCMs with concentrations (ΣLCMs) ranging from 43.7 ng/g to 448 ng/g were detected in the collected VACF dust. Additional analysis revealed the potential interactions between indoor environmental conditions and human exposure risks associated with the detected LCMs in VACF dust. The service area and working time of the ventilation and air conditioning system, and the number of indoor LCD screens were positively correlated with the fluorinated ΣLCMs in VACF dust (r = 0.355 ∼ 0.511, p < 0.05), while the associations with the non-fluorinated ΣLCMs were not found (p > 0.05), suggesting different environmental behavior and fates of fluorinated and non-fluorinated LCMs in the indoor environment. Four main indoor sources of LCMs (i.e., computer (37.1%), television (28.3%), Brand A smartphone (21.2%) and Brand S smartphone (13.4%)) were identified by positive matrix factorization-multiple linear regression (PMF-MLR). Exposure to 14 relatively frequently detected LCMs, individually and in the mixture, induced significant oxidative stress in BEAS-2B cells. Among them, non-fluorinated LCMs, specifically 3cH2B and MeP3bcH, caused dominant decreased cell viability. This study provides new insights into the indoor LCMs pollution and the associated potential health risks due to the daily use of electronic devices. [ABSTRACT FROM AUTHOR]

Improving the sustainability of the hydraulic fracturing water cycle of unconventional oil and gas development needs an advanced water treatment that can efferently treat flowback and produced water (FPW). In this study, we developed a robust two-stage process that combines flocculation, and iron-carbon micro-electrolysis plus sodium persulfate (ICEPS) advanced oxidation to treat field-based FPW from the Sulige tight gas field, China. Influencing factors and optimal conditions of the flocculation-ICEPS process were investigated. The flocculation-ICEPS system at optimal conditions sufficiently removed the total organic contents (95.71%), suspended solids (92.4%), and chroma (97.5%), but the reaction stoichiometric efficiency (RSE) value was generally less than 5%. The particles and chroma were effectively removed by flocculation, and the organic contents was mainly removed by the ICEPS system. Fourier-transform infrared spectroscopy (FTIR) analysis was performed to track the changes in FPW chemical compositions through the oxidation of the ICEPS process. Multiple analyses demonstrated that PS was involved in the activation of Fe oxides and hydroxides accreted on the surface of the ICE system for FPW treatment, which led to increasing organics removal rate of the ICEPS system compared to the conventional ICE system. Our study suggests that the flocculation-ICEPS system is a promising FPW treatment process, which provides technical and mechanistic foundations for further field application. [Display omitted] • The flowback and produced water is treated by Iron carbon micro electrolysis process and persulfate for the first time. • PS can promote the corrosion of iron anode and release more Fe2+. • The treated FPW meets the requirements of class I standard of integrated wastewater discharge standard. [ABSTRACT FROM AUTHOR]

[Display omitted] • Atmospheric release of PFAS intermediates was evidenced during waste treatment. • Landfills could be a point source of airborne PFAS into the atmosphere. • PFOS exhibited a consistent and distinct peak in the coarse particulate fraction. • Deposition of particulate PFAS in human lung was predicted to be size-dependent. Per- and polyfluoroalkyl substances (PFAS) have been applied in numerous industrial and consumer products, the majority of which flow into waste management infrastructures (WMIs) at the end of their life cycles, but little is known about atmospheric releases of PFAS from these facilities. In this study, we addressed this key issue by investigating 49 PFAS, including 23 ionic and 26 neutral and precursor PFAS, in the potential sources (n = 4; within or adjacent to WMIs) and reference sites (n = 2; coastal and natural reserve sites) in urban and rural areas of Hong Kong, China. Duplicate samples of air and size-segregated particulate matter were collected for 48 h continuously using a 11-stage Micro-Orifice Uniform Deposit Impactor (MOUDI). In general, fluorotelomer alcohols (FTOHs) and perfluoroalkane sulfonamides were the predominant PFAS classes found across sampling sites. We also demonstrated the release of several less frequently observed semivolatile intermediate products (e.g., secondary FTOHs) during waste treatment. Except for perfluorooctane sulfonate, the size-segregated distributions of particulate PFAS exhibited heterogeneity across sampling sites, particularly in the WMIs, implying combined effects of sorption affinity and emission sources. A preliminary daily air emission estimation revealed that landfill was a relatively important source of PFAS relative to the wastewater treatment plant. A simplified International Commission on Radiological Protection model was used to estimate lung depositional fluxes, and the results showed that inhaled particulate PFAS were mainly deposited in the head airway while fine and ultrafine particles carried PFAS deeper into the lung alveoli. The cumulative daily inhalation dose of gaseous and particulate PFAS ranged from 81.9 to 265 pg/kg/d. In-depth research is required to understand the health effect of airborne PFAS on workers at WMIs. [ABSTRACT FROM AUTHOR]

[Display omitted] • An auxin-like supermolucule was synthesised in laboratory. • Cell numbers of Phaeodactylum tricornutum were significantly improved. • Biomass of P. tricornutum cells was remarkably enhanced. • Eicosapentaenoic acid content of P. tricornutum was higher than similar reports. Phaeodactylum tricornutum , a model alga, is well known for its ability to accumulate intracellular omega-3 eicosapentaenoic acid (EPA). However, P. tricornutum cells need to have a higher EPA content if they are to be used for industrial applications. In this study, an auxin-like supermolecule (SM) was synthesised and used for the cultivation of P. tricornutum. Results show that the addition of 1 ppm of SM significantly increased the P. tricornutum cell density and boosted the P. tricornutum biomass. The experimental group treated with 5 ppm of SM, had an EPA content of 31.7%, which was a 2.09-fold increase over the EPA content in the untreated group. Overall, our results demonstrated that SM can significantly improve the microalgal growth and EPA accumulation in P. tricornutum , providing a feasible strategy to achieve efficient and cost-effective EPA production. [ABSTRACT FROM AUTHOR]

The stagnant supply of wild stocks of deep-sea fish and the potential bioaccumulation of toxic pollutants have promoted the research on more sustainable alternatives for the production of valuable polyunsaturated fatty acids (PUFAs) for human supplements. The diatom Phaeodactylum tricornutum has emerged as a promising alternative to oils from deep-sea fish for PUFA production. However, the level of PUFA production by native microalgal strains is not high enough for commercial applications. Improved phenotypes of native microalgal species are urgently required to fulfil commercial demands and achieve economic and environmental sustainability. In this study, we subjected wild-type P. tricornutum to a two-factor adaptive evolution process to successfully generate an evolved strain, ALE-Pt1, with enhanced biomass and PUFA production capabilities under high-glucose conditions. We used food waste hydrolysate as a primary negligible-value carbon source and a substitute for purified glucose for ALE-Pt1 cultivation under mixotrophic conditions, to improve biomass yield and PUFA production. The semi-continuous fermentation of ALE-Pt1 using food waste resulted in the production of 7.8 g of biomass and 0.87 g of eicosapentaenoic acid from a 2.8-L culture volume in a 2-L bioreactor. This microalgae-based food waste upcycling loop, combined with an adaptive evolution process, is a promising PUFA production strategy. Our results provide novel insights into PUFA production via sustainable microalgal-based waste valorisation. [Display omitted] • Two-factor adaptive evolution of P. tricornutum (ALE-Pt1) was successfully achieved. •The evolved strain ALE-Pt1 yielded higher biomass and PUFA accumulation. •Glucose-rich food waste hydrolysate contributed microalgal PUFA biosynthesis. •A food waste upcycling loop was established by semi-continuous fermentation. [ABSTRACT FROM AUTHOR]