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Shale gas has been extensively extracted in the Sichuan Basin in China in recent years. To gain insight into the potential impact of shale gas wastewater (SGW) discharge, sediment in a small river receiving treated SGW, as well as cultivated soil and paddy soil irrigated by the river water were collected. The occurrence and distribution of polycyclic aromatic compounds (PACs), including polycyclic aromatic hydrocarbons (PAHs) and their alkylated/oxygenated derivatives (APAHs/OPAHs), and thiophenes were investigated, the resultant potential ecological risks were assessed subsequently. The total concentration of PACs varied in the range of 1299.9-9286.4, 2069.4-11,512.3, and 475.7-2927.9 ng/g in sediment, cultivated soil and paddy soil, respectively, with thiophenes followed by APAHs being the abundant components in all the studied samples, demonstrating the potential impact of SGW discharge on sediment and surrounding soil environment. Based on the measured concentrations, potential ecological risks posed by PAHs and APAHs were calculated, and moderate to high ecological risks were observed in partial sampling sites, which mainly caused by 3-4 rings PAHs and APAHs.

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To understand the environmental impact of anthropogenic activities, the high-resolution temporal and compositional variations of polycyclic aromatic hydrocarbons (PAHs), oxygenated PAHs, and synthetic musks, related to human activities were investigated in a sediment core taken from the Pearl River Estuary, southern China. The temporal trend of the target compounds was evidence of the considerable impact of anthropogenic activities in the Pearl River Delta. Two significant increases of the target compounds levels in the sediment core were aligned with two nodes of key periods of economic development in China, namely, the foundation of People's Republic of China (1950s) and China's accession to the World Trade Organization (2000s). Subsequently, the significant decline of the target compounds in sediments from the 2010s indicated the successful regulation of pollutant discharges and pollution control measures. The increase in the contribution of higher molecular weight PAHs suggested a potential transition from agricultural activities to industrial activities.

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Bisphenols (BPs) and parabens (PBs) are of great concern for environmental pollution and human health because of their endocrine-disrupting effects and potential health hazards. Urinary biomonitoring of BPs and PBs can provide basic data for human internal exposure evaluation, which is a prerequisite for accurately assessing their health risks. In this study, we developed a new pretreatment procedure based on solid supported liquid-liquid extraction (SLE) for the simultaneous separation of ten BPs and five PBs in human urine, followed by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) analysis. In the instrumental analysis, the HPLC conditions and MS/MS parameters were comprehensively optimized. Accurate qualitative and quantitative determination of ten BPs and five PBs was achieved by introducing a ternary gradient elution system of water, methanol, and acetonitrile for LC separation. During sample pretreatment, the extraction solvent and elution volume were optimized. Specifically, urine samples were held at room temperature and centrifuged at 3000 r/min for 10 min. The supernatant (2 mL) was then transferred to a glass tube, and the pH was adjusted to 5.0 using HCl (0.5 mL; 0.1 mol/L) and NaAc-HAc buffer (1.5 mL). Thereafter, ß-glucuronidase-arylsulfatase (20 µL) and surrogate standard solutions (10 ng;13C12-BPS,13C12-BPAF,13C6-MeP, and 13C6-BuP) were added, and the mixture was incubated in a shaker bath in the dark at 37 ℃ for 16 h. After incubation, the hydrolyzed sample (4 mL) was loaded onto an SLE cartridge and equilibrated for a minimum of 5 min to ensure the solution was completely absorbed by the packing material. Subsequently, the target chemicals were eluted with a mixed ethyl acetate/n-hexane solution (3∶7, v/v; 15 mL). Separation of the targets was performed on a ZORBAX SB-C18 reversed-phase column (250 mm×4.6 mm, 5 µm) using an acetonitrile-methanol-water system as the mobile phase. The method was verified by spiking mixed urine samples at three levels (1, 5, and 50 µg/L), with the recoveries ranging from 84.3% to 119.8%. Except for bisphenols (BPS), whose matrix effect was calculated as -21.8%, the matrix effects of other analytes were lower than 20%, indicating low matrix interference. The linear ranges of the analytes varied from 0.1-500 µg/L to 1-500 µg/L, with correlation coefficients higher than 0.995. The method limits of quantification for target chemicals ranged from 0.03 to 0.30 µg/L, and the relative standard deviations of intra- and inter-day experiments were 1.4%-8.4% and 5.7%-14.6%, respectively, suggesting high stability and reproducibility. The method was successfully applied to the determination of ten BPs and five PBs in 10 urine samples from a general population. The concentrations of target chemicals in the human urine samples varied. Methylparaben (MeP), ethylparaben (EtP), propylparaben (PrP), and bisphenol A (BPA) were detected in all samples, with median mass concentrations of 1.10, 0.60, 0.21, and 0.55 µg/L, respectively. The detection rates of the other chemicals were less than 50%, which may be related to the production and use of specific chemicals, their bioavailability, and biological metabolism in humans.

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E-waste recycling activities are a crucial emission source of organic pollutants, posing potential risks to the surrounding environment and human health. To understand the potential impact related to diverse e-waste dismantling activities, we investigated two categories of popular flame retardants (i.e., organophosphate esters (OPEs) and chlorinated paraffins (CPs) and their resultant possible ecological risk in 53 surface soil samples from Qingyuan, a well-known e-waste recycling region in South China. Varied concentrations of ΣOPEs (20.5-8720 ng/g) and ΣCPs (920-16800 ng/g) were observed at diverse dismantling sites, while relatively low levels of ΣOPEs (6.13-1240 ng/g) and ΣCPs (14.8-2870 ng/g) were found in surrounding soils. These results indicated that primitive e-waste dismantling processes were the primary emission source of OPEs and CPs in the studied area, with e-waste dumping and manual dismantling being the most important emission sources for OPEs and CPs. More importantly, CPs could be degraded/transformed into more toxic intermediates via dechlorination and decarbonization during the burning of e-waste. Furthermore, our results indicated the potential ecological risks posed by OPEs and CPs related to e-waste recycling.

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Tris(2-chloroethyl) phosphate (TCEP) is of growing public concern worldwide because of its ubiquitous contamination, toxicity, and persistence. In this study, we investigated bacterial communities in aerobic enrichment cultures with TCEP and its two major transformation products bis(2-chloroethyl) phosphate (BCEP) and 2-chloroethanol (2-CE) as the sole carbon source. Burkholderiales and Rhizobiales were likely two main bacterial guilds involved in the hydrolysis of TCEP, while Rhizobiales and Sphingomonadales may play an important role in the hydrolysis of BCEP, given the increase of Rhizobiales and Sphingomonadales-related phosphoesterase genes when the carbon source was switched from TCEP to BCEP. All Burkholderiales, Rhizobiales, Sphingomonadales were probably efficient in 2-CE metabolism, because their dehydrogenase genes and dehalogenase genes increased after 2-CE enrichment. The different substrate preference of different bacterial guilds highlighted the importance to understand the diversity and collaboration among functional bacteria. Meanwhile, two TCEP-degrading strains affiliated with Xanthobacter and Ancylobacter were isolated. Xanthobacter sp. strain T2-1 was able to degrade both TCEP and BCEP following the pseudo-first-order kinetics with reaction rates of 1.66 h-1 for TCEP and 1.02 h-1 for BCEP, respectively. Ancylobacter sp. strain T3-4 could degrade TCEP following the pseudo-first-order kinetics with a reaction rate of 2.54 h-1, but is unable to degrade BCEP. Additionally, strains that were phylogenetically closely related were found to have different degradation capabilities toward TCEP and/or BCEP, indicating the importance to investigate functional genes such as phosphoesterase genes.

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Polyhalogenated carbazoles (PHCZs) are a group of emerging organic pollutants attracting increasing concern. In this study, 32 sediment samples were collected from the Pearl River Estuary (PRE) and adjacent Daya Bay (DYB) in China and were investigated for the occurrence and distribution of PHCZs. Total concentration of sedimentary PHCZs (∑PHCZs) ranged from 0.79 to 3.08 ng/g in PRE and 0.89 to 1.95 ng/g in DYB, both containing 3,6-dichlorocarbazole as the main component. Higher concentrations of ∑PHCZs were found in the rivers-mouth and inner part of the PRE indicating their main origins from anthropogenic activities. Notably, concentrations of brominated carbazoles (BCZs) gradually increased offshore, which suggests the potential bio-transformation of BCZs under a saline environment. The toxic equivalent of PHCZs was estimated at 0.13-0.34 pg TEQ/g suggesting limited dioxin-like effects on local organisms.

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Eight paired organophosphate diesters (Di-OPs) and organophosphate triesters (Tri-OPs) were investigated in wipes from analytical instruments and 47 material samples related to household products, including textiles, electrical/electronic devices, building/ decoration materials and children's products. The total concentrations of Di-OPs ranged in 3577-95551 ng/m2 in the wipes and limit of detection-23002 ng/g in the materials. The Tri-OPs concentrations varied significantly in the ranges of 107218-1756892 ng/m2 and 2.13-503149 ng/g, respectively. Four industrial Di-OPs were detected in > 65% of the studied samples suggesting their direct application in the studied materials. Furthermore, we demonstrated for the first time that four non-industrial Di-OPs, e.g., bis(2-chloroethyl) phosphate, bis(1-chloro-2-propyl) phosphate, bis(1,3-dichloro-2-propyl) phosphate, and bis(butoxyethyl) phosphate, identified as degradation products of their respective Tri-OPs were also detected in these studied samples, which might act as important emission sources of Di-OPs in indoor environments. We estimated the burden of Di-OPs and Tri-OPs in a typical residential house and instrumental room, which both exhibited important contributions from furniture, building and decoration materials, and electrical/electronic devices. Limit health risk was posed to local people via air inhalation.

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Recent screening surveys have shown the presence of unknown source halogenated organic compounds (HOCs) in shale gas wastewater. However, their occurrence, profile, transport in surrounding surface water and environmental risk potentials remain unclear. Here, a method for the extraction and quantitative determination of 13 HOCs in water by solid phase extraction combined with gas chromatography-mass spectrometry (GC-MS) was established. All of the targeted HOCs were detected and peaked at the outfall, while these contaminants were generally not detected in samples upstream of the outfall, suggesting that these contaminants originated from the discharge of shale gas wastewater; this was further supported by the fact that these pollutants were generally detected in downstream samples, with a tendency for pollutant concentrations to decrease progressively with increasing distance from the outfall. However，different HOCs had different transport potential in water. In addition, the toxicological effects of typical HOCs were evaluated using HepG2 as a model cell. The results indicated that diiodoalkanes suppressed HepG2 cell proliferation and induced ROS generation in a concentration-dependent manner. Mechanistic studies showed that diiodoalkanes induced apoptosis in HepG2 cells via the ROS-mediated mitochondrial pathway, decreasing mitochondrial membrane potential and increasing intercellular ATP and Ca2+ levels. On the other hand, RT-qPCR and Western blot assays revealed that the SLC7A11/GPX4 signaling pathway and HO-1 regulation of ferritin autophagy-dependent degradation (HO-1/FTL) pathway were involved in the ferroptosis pathway induced by diiodoalkane in HepG2 cells. Our study not only elucidates the contamination profiles and transport of HOCs in surface water of typical shale gas extraction areas in China, but also reveals the toxicity mechanism of typical diiodoalkane.

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Flowback and produced water (FPW) generated from shale gas extraction is a complex mixture consisting of injected drilling fluid, deep formation water, and byproducts of downhole reactions. Limited knowledge is available regarding the impact of discharged FPW on surface water in China. With the development of shale gas exploitation, this emphasizes an urgent need for comprehensive assessments and stringent regulations to ensure the safe disposal of shale gas extraction-related wastewater. Herein, we explored potential impacts of treated shale gas wastewater discharged into a local river in southwest China through toxicity identification evaluation (TIE). Results revealed that organics and particulates significantly contributed to the overall toxicity of the treated FPW wastewater. Through target and suspect chemical analyses, various categories of organic contaminants were detected, including alkanes, aromatic hydrocarbons, biocides, phenols, and phthalates. Furthermore, non-target analysis uncovered the presence of surfactant-related contaminants in tissues of exposed organisms, but their contribution to the observed toxicity was unclear due to the lack of effect data for these compounds. Higher toxicity was found at the discharge point compared with upstream sites; however, the toxicity was rapidly mitigated due to dilution in the receiving river, posing little impact on downstream areas. Our study highlighted the importance of monitoring toxicity and water quality of FPW effluent even though dilution could be a viable approach when the water volume in the discharge was small.

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The potential contamination of shale gas wastewater generated from hydraulic fracturing to water resources is of growing concern, yet minimum attention has been paid to the impact of shale gas wastewater on the trace elements of the receiving waters. In this study, we analyzed the levels of 50 trace elements of a river that receives effluent from a shale gas wastewater treatment facility in the Sichuan Basin, China. Sixteen trace elements were detected in the surface water sample from the effluent discharge site, all of which were of higher concentrations than the upstream background level. Among the 16 shale gas wastewater-related elements, Sr, Ba, and Li were of elevated levels in the downstream water samples (24.9-44.2%, 5.0-8.0 times, and 17.8-22.8 times higher than the upstream background level, respectively). Shale gas wastewater effluent may be related to the accumulation of Sr, Ba, Li, and Cs in riverbed sediments near and/or downstream of the effluent discharge site and may lead to elevated pollution level of Sr and Li in downstream sediments. The ecological risk of the riverbed sediments was of medium to high level, with Cd contributing to the most risk, while shale gas wastewater-related elements are of low potential risk throughout the river. Our results suggested that shale gas wastewater effluent discharge had limited impacts on the trace elements of the receiving river within two years.

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Hydraulic fracturing flowback and produced water (HF-FPW) from shale gas extraction processes is a highly complex medium with potential threats to the environment. Current research on ecological risks of FPW in China is limited, and the link between major components of FPW and their toxicological effects on freshwater organisms is largely unknown. By integrating chemical and biological analyses, toxicity identification evaluation (TIE) was used to reveal causality between toxicity and contaminants, potentially disentangling the complex toxicological nature of FPW. Here, FPW from different shale gas wells, treated FPW effluent, and a leachate from HF sludge were collected from southwest China, and TIE was applied to obtain a comprehensive toxicity evaluation in freshwater organisms. Our results showed that FPW from the same geographic zone could cause significantly different toxicity. Salinity, solid phase particulates, and organic contaminants were identified as the main contributors to the toxicity of FPW. In addition to water chemistry, internal alkanes, PAHs, and HF additives (e.g., biocides and surfactants) were quantified in exposed embryonic fish by target and non-target tissue analyses. The treated FPW failed to mitigate the toxicity associated with organic contaminants. Transcriptomic results illustrated that organic compounds induced toxicity pathways in FPW-exposed embryonic zebrafish. Similar zebrafish gene ontologies were affected between treated and untreated FPW, again confirming that sewage treatment did not effectively remove organic chemicals from FPW. Thus, zebrafish transcriptome analyses revealed organic toxicant-induced adverse outcome pathways and served as evidence for TIE confirmation in complex mixtures under data-poor scenarios.

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Chlorinated paraffins (CPs), a group of mixtures with different carbon chain lengths and chlorine contents, are widely used as plasticizers and flame retardants in various indoor materials. CPs could be released from CP-containing materials into the ambient environment and then enter the human body via inhalation, dust ingestion and dermal absorption, resulting in potential effects on human health. In this study, we collected residential indoor dust in Wuhan, the largest city in central China, and focused on the co-occurrence and composition profiles of CPs as well as the resultant human risk via dust ingestion and dermal absorption. The results indicated that CPs with C9-40 were ubiquity in indoor dust with medium-chain CPs (MCCPs, C14-17) as the main components (6.70-495 µg g-1), followed by short-chain CPs (SCCPs, C10-13) (4.23-304 µg g-1) and long-chain (LCCPs, C≥18) CPs (3.68-331 µg g-1). Low levels (not detected-0.469 µg g-1) of very short-chain CPs (vSCCPs, C9) were also found in partial indoor dust. The dominant homolog groups were C9 and Cl6-7 groups for vSCCPs, C13 and Cl6-8 groups for SCCPs, C14 and Cl6-8 groups for MCCPs, and C18 and Cl8-9 groups for LCCPs. Based on the measured concentrations, vSCCPs, SCCPs, MCCPs, and LCCPs posed limited human health risks to local residents via dust ingestion and dermal absorption.

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For decades, the presence and potential health risk of polycyclic aromatic hydrocarbons (PAHs) in indoor dust have been extensively investigated while with limited attention to oxygenated PAHs (OPAHs). In this study, we collected 45 indoor dust from four microenvironments in Guangzhou City, China, and then focused on the co-occurrence of 16 PAHs and 8 OPAHs and their potential carcinogenic risk to humans. The ΣPAHs concentrations, dominated by 4-6 ring PAHs, ranged from 1761 to 14,290 ng/g (mean of 6058 ng/g) without significant difference in the different microenvironments (Tukey, p > 0.05). The OPAHs were observed with concentrations from 250 to 5160 ng/g (mean of 1646 ng/g), and anthraquinone (AQ) was identified as the main OPAHs with significantly high levels in the residential environment than in instrumental rooms. Notably, AQ dominated over the other target analytes in dust in this study. Our results indicated that PAHs and OPAHs in indoor dust were from outdoor environments, which mainly originated from vehicular exhaust and biomass/coal combustion. A potential cancer risk of PAHs and OPAHs to local adults and children was observed via inhalation, ingestion, and dermal absorption, with the main contribution from benzo[a]pyrene and dibenz[a,h]anthracene.

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The regional characteristics of atmospheric organophosphate triesters (OPEs) and organophosphate diesters (Di-OPs) in the Pearl River Delta (PRD) were investigated by passive air samplers mounting quartz fiber filters. The analytes were found on a regional scale. Atmospheric OPEs, semi-quantified using sampling rates of particulate-bonded PAHs, were in the range of 537-2852 pg/m3 in spring and in the range of 106-2055 pg/m3 in summer, with tris(2-chloroethyl)phosphate (TCEP) and tris(2-chloroisopropyl)phosphate as the main components. While atmospheric Di-OPs were semi-quantified using sampling rates of SO42-, in the range of 22.5-5576 pg/m3 in spring and in the range of 66.9-1019 pg/m3 in summer, with di-n-butyl phosphate and diphenyl phosphate (DPHP) being the main Di-OPs. Our results indicated that OPEs were mainly distributed in the central part of the region, which might be ascribed to the distribution of industry related to OPE-containing products. In contrast, Di-OPs were scattered in the PRD, suggesting local emission from their direct industrial application. Significantly lower levels of TCEP, triphenyl phosphate (TPHP), and DPHP were detected in summer than in spring, implying that these compounds might be partitioned off particles as the temperature increased and due to possible photo-transformation of TPHP and DPHP. The results also suggested the long-distance atmospheric transportation potential of Di-OPs.

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The accuracy of compound-specific isotope analysis (CSIA) of trace-level pollutants in complex environmental samples has always been limited by two main challenges: poor chromatographic separation and insufficient amounts of analytes. In this study, a two-dimensional gas chromatography-isotope ratio mass spectrometry (2DGC-IRMS) system was constructed for compound-specific δ13C analysis of high molecular weight polycyclic aromatic hydrocarbons (HMW-PAHs) in estuarine/marine sediments. This construction occurred through hyphenating an extra gas chromatography system (GC) to a conventional GC-IRMS using a commercially available multi-column switching-cryogenic trapping system (MCS-CTS). Compared with the previous 2DGC-IRMS strategy, which utilizes a Deans Switch device, the newly implemented 2DGC-IRMS scheme resulted in online purification of target analytes as well as enriched them online via duplicate injection and cryogenic trapping in CTS; this resultingly lowered the limits of detection (LOD) of CSIA. To improve the sample transfer efficiency to the IRMS, a broader-bore and longer fused-silica capillary was utilized to replace the original sample capillary running from the sample open split to the IRMS. A ẟ13C analysis of PAH standards showed accurate ẟ13C values, and high precisions (standard deviations 0.13-0.37%) were achieved, with the LOD of HMW-PAHs reduced to at least 1.0 mg/L (i.e., 0.07 to 0.09 nmol carbon per compound on-column). The successful application of this newly developed 2DGC-IRMS scheme provides a practical solution for the reliable CSIA of trace-level pollutants in complex environmental samples that cannot be measured using the conventional GC-IRMS system.

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Organophosphate esters (OPEs) are emerging contaminants of growing concern, and there is limited information about the bacterial transformation of OPEs. In this study, we investigated the biotransformation of tris(2-butoxyethyl) phosphate (TBOEP), a frequently detected alkyl-OPE by a bacterial enrichment culture under aerobic conditions. The enrichment culture degraded 5 mg/L TBOEP following the first-order kinetics with a reaction rate constant of 0.314 h-1. TBOEP was mainly degraded via ether bond cleavage, evidenced by the production of bis(2-butoxyethyl) hydroxyethyl phosphate, 2-butoxyethyl bis(2-hydroxyethyl) phosphate, and 2-butoxyethyl (2-hydroxyethyl) hydrogen phosphate. Other transformation pathways include terminal oxidation of the butoxyethyl group and phosphoester bond hydrolysis. Metagenomic sequencing generated 14 metagenome-assembled genomes (MAGs), showing that the enrichment culture primarily consisted of Gammaproteobacteria, Bacteroidota, Myxococcota, and Actinobacteriota. One MAG assigned to Rhodocuccus ruber strain C1 was the most active in the community, showing upregulation of various monooxygenase, dehydrogenase, and phosphoesterase genes throughout the degradation process, and thus was identified as the key degrader of TBOEP and the metabolites. Another MAG affiliated with Ottowia mainly contributed to TBOEP hydroxylation. Our results provided a comprehensive understanding of the bacterial TBOEP degradation at community level.

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The evaluation of the sorption affinity of fluoroquinolone antibiotics (FQs) in soils, by means of the derivation of solid-liquid distribution coefficients (Kd), is a valuable information for assessing their environmental mobility. Aiming to develop Kd (FQ) prediction tools in soils, in the first stage of this study we constructed a Kd (FQ) sorption dataset using current literature data. Furthermore, additional sorption and desorption data for norfloxacin were obtained in seven different soils of contrasting properties. Sorption isotherms of norfloxacin were linear under the experimental conditions tested and desorption percentages increased for scenarios in which low sorption was noted. Sorption tests in the same soils were then extended to ciprofloxacin, enrofloxacin and ofloxacin and pooled in the dataset, revealing comparable Kd (FQ) values among the FQ tested after analyzing the overall dataset consisting in 312 entries of Kd (FQ). A partial least square (PLS) regression model was then developed to predict values of Kd (FQ) based on specific relevant soil properties (i.e., pH, cation exchange capacity and organic carbon and texture information), and, for the first time, FQ properties (fraction of cationic FQ species) affecting sorption. Additionally, probabilistic, Kd (FQ) best estimates in soils were derived through cumulative distribution functions (CDFs) for the overall and for partial datasets created by grouping Kd (FQ) values according to key soil properties affecting FQ sorption (i.e., pH, organic carbon content and texture information). This latter approach permitted to derive more representative Kd (FQ) best estimates for the soils to be assessed, and with a lower related variability than that derived from the overall dataset. Best estimates Kd (FQ) values were > 1000 L kg-1 for most acidic to neutral soils, suggesting strong sorption, although lower sorption and thus higher environmental mobility may be expected in scenarios with soils with alkaline pH, low OC and high sand contents. SYNOPSIS: This study aims to derive parametric and probabilistic Kd values for fluoroquinolone antibiotics in soils on the basis of a few relevant soil physicochemical properties.

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As new pollutants, microplastics (MPs) can adsorb antibiotics in the water environment and migrate together as carriers. However, microplastics will age continuously in the environment, and their adsorption capacity and adsorption mechanism will change accordingly. With polyethylene (PE) and polystyrene (PS) as the target MPs, which were irradiated by ultraviolet (UV-254), the changes in the physical and chemical properties of MPs before and after aging, such as the color, surface morphology, and functional groups, were compared, and their effects on the adsorption of tetracycline (TC) as well as the related mechanism were explored. The results showed that the pseudo-second-order model could better fit the adsorption process, the adsorption equilibrium was reached within 24 hours, the adsorption capacity of aged MPs for TC was significantly higher than that of original MPs, and the adsorption capacity of PS was higher than that of PE. Langmuir and Freundlich isothermal adsorption equations could both describe the adsorption isothermal test data, and the adsorption of TC on MPs was a spontaneous and endothermic physical adsorption process, whereas aging had no obvious effect on the adsorption thermodynamic characteristics of MPs. With the increase in pH value, the adsorption capacity first increased and then decreased. The maximum adsorption capacity of MPs before and after aging was reached at pH=5. UV aging increased the specific surface area of MPs, generating oxygen-containing functional groups such as -C＝O, -OH, and O＝C＝O, changing the physical and chemical properties of MPs, and thus changing the adsorption mechanism of MPs for TC. Compared with the original PE MPs, in addition to hydrophobic distribution, van der Waals forces, and electrostatic interactions, pore filling was also an important adsorption mechanism of aged PE. The main adsorption mechanisms of original PS microplastics were hydrophobic distribution, van der Waals forces, electrostatic interaction, and π-π interaction, whereas there was hydrogen bonding for aged PS.

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In this study, a method was established for the analysis of long-chain chlorinated paraffins (LCCPs) in sediment based on quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction and two-dimensional liquid chromatography-Orbitrap high resolution mass spectrometry (2DLCOrbitrap HRMS). Compared with other reported methods, this method greatly reduces sample preparation time (2 h) and solvent consumption. The QuEChERS extraction method presented satisfactory recoveries, 90.5-95.2, 84.7-86.6, and 81.4-83.4% of 5, 50, and 200 ng/g LCCPs with 49% Cl spiked into sediments. Meanwhile, no matrix effects were found in the LCCPs analysis after online purification by the 2DLC system. With the current commercial LCCP standards and a mixture of three chlorinated paraffins (CPs) industrial products, a suspect screening strategy was established and accurate identification of LCCPs (including vLCCPs, which carbon chain length greater than 20) under the plight that the reference standards for vLCCPs are currently unavailable. A total of 21 C18-20-LCCP and 22 vLCCP congeners were identified in sediment samples collected from Dongting Lake, China. The total concentrations of LCCPs in six sediment samples ranged from 1.69 to 18.0 ng/g (median 6.66 ng/g) and was dominated by C18 groups (mean, 28.8%), C19 groups (mean, 19.1%) and C21 groups (mean, 16.9%). Taken together, the successful application of this method to analyze sediment samples shows great potential for the analysis of LCCPs in environmental samples in future studies.

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The transformation products of triclosan (5-chloro-2-(2,4-dichlorophenoxy)phenol) may be more persistent and toxic than their parent compound, yet their occurrence in aquatic environments is poorly understood. In this study, we identified three transformation products in sediment samples from Taihu Lake and compared their concentrations with the parent compound triclosan. Triclosan in Taihu Lake was at low level, ranging from 0.086 to 1.1 ng/L in surface water and 0.0058-8.3 ng/g in sediments. The three detected transformation products included methyl triclosan, chlorinated triclosan derivatives, and methyl chlorinated triclosan derivatives. Those transformation products constituted 0.73-87.5% of the total triclosan (total triclosan is the sum of triclosan, methyl triclosan, chlorinated triclosan derivatives, and methyl chlorinated triclosan derivatives on a molar basis), indicating that the ecological risk of transformation products should be considered in addition to the parent compound. Different transformation products had distinct spatial distributions. Chlorinated triclosan derivatives had the highest concentration in samples from the northwest region (0.016-0.21 ng/g) of the lake and were positively correlated with triclosan, which may indicate the possible transformation from triclosan to chlorinated triclosan derivatives. Methyl triclosan and methyl chlorinated triclosan derivatives were generally higher in samples from the center of the lake (0.22-0.28 ng/g for methyl triclosan and 0.017-0.021 ng/g for methyl chlorinated triclosan derivatives, respectively), indicating the possible occurrence of in situ microbial methylation of triclosan and chlorinated triclosan derivatives and the accumulation of those methylated analogues in Taihu Lake.

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