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The widespread application of organophosphate flame retardants has led to pervasive exposure to organophosphate esters (OPEs), prompting considerable concerns regarding their potential health risk to humans. Despite hints from previous research about OPEs' association with breast cancer, their specific effects and underlying mechanisms of triple-negative breast cancer (TNBC) remain unclear. In this study, we investigated the effects of four representative OPEs on cell proliferation, cell cycle regulation, migration, and the expression of genes and proteins associated with the epidermal growth factor receptor (EGFR) and Hippo signaling pathways in TNBC (MDA-MB-231) cells. Our findings revealed that treatment with 1–25 μM triphenyl phosphate (TPHP) and tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) induced TNBC cell proliferation and accelerated cell cycle progression, with upregulation in MYC, CCND1, and BRCA1 mRNA. Moreover, exposure to 1–25 μM TPHP, 10–25 μM TDCIPP, and 1–10 μM tris (2-chloroethyl) phosphate (TCEP) induced MMP2/9 mRNA expression and enhanced migratory capacity, except for 2-ethylhexyl diphenyl phosphate (EHDPP). Mechanistically, four OPEs treatments activated the EGFR-ERK1/2 and EGFR-PI3K/AKT signaling pathways by increasing the transcript of EGFR, ERK1/2, PI3K, and AKT mRNA. OPEs treatment also suppressed the Hippo signaling pathway by inhibiting the expression of MST1 mRNA and phosphorylation of LATS1, leading to the overactivation of YAP1 protein, thereby promoting TNBC cell proliferation and migration. In summary, our study elucidated that activation of the EGFR signaling pathway and suppression of the Hippo signaling pathway contributed to the proliferation, cell cycle dysregulation, and migration of TNBC cells following exposure to OPEs. [ABSTRACT FROM AUTHOR]

Indoor dust is the main source of human exposure to brominated flame retardants (BFRs). In this study, in vitro colon-extended physiologically-based extraction test (CE-PBET) with Tenax as a sorptive sink was applied to evaluate the oral bioaccessibility of twenty-two polybrominated diphenyl ethers (PBDEs) and seven novel BFRs (NBFRs) via indoor dust ingestion. The mean bioaccessibilities of two NBFRs pentabromotoluene (PBT) and 1,2-Bis(2,4,6-tribromophenoxy) ethane (BTBPE) were first proposed, reaching 36.0% and 26.7%, respectively. In order to maintain homeostasis of the gastrointestinal tract, 0.4 g Tenax was added in CE-PEBT, which increased BFRs bioaccessibility by up to a factor of 1.4–1.9. The highest bioaccessibility of legacy PBDEs was tri-BDEs (73.3%), while 2-ethylhexyl-tetrabromo-benzoate (EHTBB), one of penta-BDE alternatives, showed the highest (62.2%) among NBFRs. The influence of food nutrients, liquid to solid (L/S) ratio, and octanol–water partition coefficient (Kow) on bioaccessibility was assessed. The oral bioaccessibility of BFRs increased with existence of protein or carbohydrate while lipid did the opposite. The bioaccessibilities of PBDEs and NBFRs were relatively higher with 200:1 L/S ratio. PBDEs bioaccessibility generally decreased with increasing LogKow. No significant correlation was observed between NBFRs bioaccessibility and LogKow. This study comprehensively evaluated the bioaccessibilities of legacy and emerging BFRs via dust ingestion using Tenax-assisted CE-PBET, and highlighted the significance to fully consider potential influencing factors on BFRs bioaccessibility in further human exposure estimation. [ABSTRACT FROM AUTHOR]

In this research, ethylene glycol-introduced solvothermal method was employed to fabricate a novel sphere-like CuBi2O4 material to improve the adsorptive and photocatalytic performance of conventional CuBi2O4. A series of characterization has been applied to investigate properties of the obtained CuBi2O4 (CBO-EG3). Compared with conventional rod-like CuBi2O4 (CBO), the synthesized sphere-like CBO-EG3 exhibited rough surface, larger specific surface area, and more effective separation of photo-generated carriers, which overcome main shortcomings of CuBi2O4. The removal efficiency of typical antibiotic sulfamethazine (SMZ) reached almost 100% under the optimal experimental conditions. About 70% of SMZ could be adsorbed in 180-min dark reaction, with residual being photodegraded in 30 min. CBO-EG3 showed much higher photocatalytic efficiency than pure CBO, attributing to its highly effective photo-induced electron and hole separation. Meanwhile, substantial adsorption of pollutant on CBO-EG3 contributed vastly to removal of SMZ, photo-generated electrons and holes inclined to react with adsorbed SMZ directly, and photocatalytic process was mainly led by non-radical reaction. Elimination of SMZ in actual water samples and recycling experiment were also performed to evaluate CBO-EG3's practical application potential. This study delivered a method to promote CuBi2O4's adsorptive and photocatalytic ability, which could expand the application of CuBi2O4 in wastewater treatment. [ABSTRACT FROM AUTHOR]

The occurrence and profiles of organophosphate flame retardants (OPFRs) were investigated in the Huangpu and Shiwuli Rivers, two urban rivers in the Yangtze River Delta, China. The total concentrations of OPEs were found at part-per-trillion ranges, with average concentrations that ranged from 424 to 1.84 × 103 ng L−1 for Huangpu River and 221 to 1.84 × 103 ng L−1 for Shiwuli River. Three chlorinated OPFRs including tris(chloroethyl) phosphate (TCEP), tris(2-chloroisopropyl) phosphate (TCIPP), and tris(1,3-dichloroisopropyl) phosphate (TDCIPP) were the most abundant compounds among the investigated OPFRs, accounting for 90.6–99.8% of total concentrations. In Huangpu River, the OPFR concentrations were significantly higher in the dry season than in the wet season which indicates obvious seasonal variation. Chlorinated OPFR concentrations differed significantly between upstream and downstream reaches of the Shiwuli River, as the result of geographic features and wastewater discharge. Estimated risk was calculated to compare predicted no-effect concentrations (PNEC) to observed concentrations of OPFRs. The results indicated no significant acute adverse effects of OPFRs in the two urban rivers for fish, daphnia, or algae. [ABSTRACT FROM AUTHOR]

Metal pollution in drinking water source has been under scrutiny as it seriously affects human health. This work examined 12 dissolved metals in the surface and overlying water of the Xiangjiang River, an important drinking water source in southern China, and characterized their distribution, identified their possible sources, assessed their toxicity load, and determined their potential ecological and health risk. No significant difference was found in the metal concentration between surface and overlying water. The average metal concentration fell in the order of Mg > Mn > Ba > Fe > Zn > As > Sb > Ni > Cd > V > Cr > Co, and all was lower than the safety threshold in the drinking water guideline of China. Anthropogenic activities were found to be the main source of metals from correlation analysis, principal component analysis (PCA), and cluster analysis (CA). According to the total heavy metal toxicity load (HMTL), 98.20%, 71.54%, 68.88%, and 7.97% of As, Cd, Sb, and Mn should be removed from the surface water to ensure safety. Most water samples from the surveyed area were found to have high ecological risk as was measured by the ecological risk index (RI). Health risk assessment showed that children are more susceptible than adults to the non-carcinogenic risk of dissolved metals, and the potential carcinogenic risk (CR) of As and Cd should be addressed. The results provide guidance for controlling the metal pollution of the Xiangjiang River and improving its quality as a drinking water source. [ABSTRACT FROM AUTHOR]

Predicting the aggregation tendency of nanoscale zero-valent iron (nZVI), oxidized nZVI, in particular, is crucial for the risk assessment of nZVI in aquatic environments. In this study, the comprehensive effects of the pH and ionic strength (IS) on the aggregation behaviors of two highly oxidized nZVIs (HO-nZVI) were examined. Compared with hematite nanoparticles, HO-nZVI presented a sudden acceleration in aggregation under critical conditions; moreover, the morphology of the HO-nZVI aggregates at pH and IS values higher or lower than the critical conditions was significantly different. Furthermore, owing to the differences in magnetization between the two prepared HO-nZVI samples, their critical coagulation conditions were significantly different. The significant changes in the aggregation behavior of the HO-nZVI samples were analyzed using colloidal theories, and the aggregation tendency of HO-nZVI under specific conditions could be simulated by calculating the theoretical critical conditions of aggregation via a method that takes into account the hydrochemical properties, magnetization, and surface charge of HO-nZVI. To examine the correctness of the method, we compared the experimentally determined colloidal stability of HO-nZVI in water samples collected from nearby rivers with the theoretically predicted value. The results indicated that the method was adequate for most situations, except for those in which the hydrochemical properties of the water samples were close to the critical coagulation conditions. Our study proposes a theoretical approach that is viable for simulating the colloidal stability of magnetic nanoparticles in aquatic environments; we anticipate that it will further facilitate the risk assessment of nanoparticles. [ABSTRACT FROM AUTHOR]

Background: Aquatic ecosystems are considered to be among the most important reservoirs of antibiotic resistance genes (ARGs). Drinking water sources could serve as critical points of ARGs transfer from environment to human. In this study, the distribution of antibiotics and ARGs across Qingcaosha Reservoir located in the Yangtze River Delta during three seasons was investigated to characterize the pollution patterns. Results: Sulfamethoxazole, sulfamonomethoxine and penicillin G potassium salt were the dominant antibiotics in this reservoir. Sulfonamide resistance genes (sul1 and sul2) were the most prevalent and predominant genes. Higher total relative abundance of the ARGs was detected in the site closest to the inflow than those in other sites. Overall, the concentrations of antibiotics in May were relatively lower than those in November and February. Correlation analysis indicated sul1, ermB and mphA had positive correlation with corresponding antibiotics in February and sul1, sul2, ermB and mphA was also positively correlated to intI1. Conclusion: In conclusion, antibiotics and ARGs were widespread in Qingcaosha Reservoir. Our results indicated that the drinking water reservoir might serve as gene reservoir for antibiotic resistance and mobile gene element intI1 can serve as a medium to contribute to the widespread of various ARGs. As the ARGs abundance was found to be higher in the inflow of the reservoir compared to the outflow, it is considered that reservoir could serve as a functional area contributing to the elimination or dilution of ARGs. [ABSTRACT FROM AUTHOR]

Background: The successful application of Fish plasma model (FPM) will greatly simplify the risk assessment of drugs. At present, the FPM has been applied to the risk assessment of several human drugs with high hydrophobicity. However, its applicability to a wide variety of compounds needs to be tested. Field work about distribution characteristics of endocrine disrupting compounds (EDCs) in water and in fish plasma plays a key role in promoting the successful application of FPM. However, there are few reports on the distribution of EDCs in fish, especially in wild fish plasma. Results: The distribution of 31 EDCs, including seven estrogens, eight androgens, six progesterones, five glucocorticoids, and five industrial compounds, in water and plasma of five categories of wild fishes in Taihu Lake was studied and the typical FPM was tested by the field data. The detected concentration of most compounds is relatively low (< 10 ng/L), and the industrial compounds are the predominant pollutants with the highest concentration up to 291.7 ng/L (Bisphenol A) in water. In general, glucocorticoids were detected at the highest concentrations in plasma of all kinds of fishes, followed by industrial compounds and estrogens. Except for glucocorticoids (up to 43.61 for Cortisone), the average concentrations of the other four categories of EDCs in fish plasma were generally low (< 10 μg/L). The available measured bioaccumulation factors (BAFs) of 20 kinds of EDCs were in the range of 0 to 5626. The bioaccumulation of EDCs in fish plasma is not only hydrophobicity-dependent, but is also both fish species-specific and compound-dependent. The classical FPM was tested and the results indicated that the good coincides of measured log BAFs and the theoretical log BCFs were only observed for limited EDCs (7 out of 20). The present available FPM generally underestimated the Log BAFs of most hydrophilic EDCs (log Kow < 3.87, 11 out of 20) whereas overestimated the Log BAFs of several high hydrophobic EDCs (Log Kow > 3.87) in fish plasma. Conclusion: Although the present FPM is barely satisfactory, it is still promising for predicting the accumulation of EDCs in fish plasma and for further environmental risk assessment. [ABSTRACT FROM AUTHOR]

Background: The discard of used adsorbents may pose a great threat to human health and ecological environment. This work herein reported a facile and feasible method, with aims of (i) reusing the calcined layered double hydroxide (CLDH) adsorbent after azo dye adsorption, and (ii) being further used as a photocatalyst to enhance the degradation of typical pharmaceuticals. Calcination under inner gas flow has been utilized to carbonize adsorbed azo dye and a kind of novel carbonaceous CLDH composite material (CM-CLDH) was synthesized. This fabricated material was used as a catalyst for Ibuprofen removal in water samples under simulated sunlight irradiation. Results: According to our experimental results, combination of carbonaceous material with CLDH showed an enhanced photocatalytic performance compared to original CLDH materials. More than 90% of Ibuprofen could be removed in less than 180 min. Introduction of carbon material narrowed catalyst's band gap and turned its conduct band potential to a more negative state, which brought considerable light absorption and higher oxidation ability of photo-induced electrons. Furthermore, photoluminescent spectra and transient photocurrent examination confirmed that carbon material suppressed recombination of photo-induced electrons and holes through faster electron transportation. Under experimental conditions, the removal efficiency of Ibuprofen by CM-CLDH composite kept above 90% during five cycles. Conclusion: Calcination under inner gas flow can transform organic pollutant-adsorbed CLDH to CM-CLDH composite with higher photocatalytic performance. A feasible way to reuse spent LDH adsorbents was proposed, which is a benefit to reduce second pollution of spent adsorbents in environment. [ABSTRACT FROM AUTHOR]

Background: The vast occurrence of organic micropollutants in surface waters has raised concerns about drinking water safety and public health. The Tai Hu Basin region in China, a typical developing and populous area, is facing the challenge of water pollution. To ensure drinking water safety, the knowledge on how treatment techniques and raw water quality affect the quality of finished water must be improved. The aim of the current study was to evaluate drinking water quality with respect to organic micropollutants and how the purity of the finished water depends on source water contamination and drinking water treatment strategies. Five drinking water treatment plants (DWTPs), using three different source waters in the Tai Hu River Basin, (i) Yangtze River, (ii) Wetland River Network, and (iii) Lake Tai Hu, were studied by analyzing 291 micropollutants in raw and finished water. Results: Major differences in concentrations and composition profiles of organic micropollutants were observed between the source waters. Among the studied micropollutants, the dominating group was pesticides in the Wetland River Network and flame retardants in Yangtze. The total concentration of poly- and perfluoroalkyl substances (PFASs) in Tai Hu water was far higher than in the other samples. In total, 51 compounds were detected in the finished water, with an overall average total concentration of 730 ± 160 ng L−1. The removal efficiency of the detected compounds in the DWTPs averaged 24 ± 150%, which highlights the major challenge for the DWTPs in removing the emerging organic micropollutants through current treatment processes. Conclusions: Our study showed that if the source water contains high levels of PFASs and organophosphorus flame retardants, even advanced treatment procedures are inefficient in removing the micropollutants, and the finished drinking water may contain cumulative levels of organic micropollutants in the ​µg L−1 range. On the other hand, if pesticides and pharmaceuticals dominate, a high overall treatment efficiencies may be obtained if advanced treatment techniques are used. The DWTPs are advised to use advanced treatment techniques or alternative water sources to guarantee the safety of drinking water. As surface water systems are highly impacted by upstream activities, efforts should also be made in the water sector for improving the surface water quality. [ABSTRACT FROM AUTHOR]

Background: Taste and odor problem in drinking water is one major concern for consumers and water supply. Exploring the odor characteristics and the major odor causing compounds in the source water is the base for odor control in drinking water treatment plant (WTP). In this study, focusing on a newly constructed reservoir with Huangpu River as the source water, the occurrence of typical odorants and their variations were first identified. Correspondingly, the removal behavior in an ozone/GAC advanced treatment process was investigated. Results: The results indicated that 2-methylisoborneol (2-MIB), geosmin (GSM), and bis (2-chloroisopropyl) ether (BCIE) have major contribution to the musty/earthy and chemical/septic odors in the source water, respectively. Pre-ozonation alone (1 mg L−1) showed limited removal for 2-MIB and BCIE, at less than 30% and 20%, respectively, while combining with coagulation, sedimentation, and sand filtration, the removals were improved to higher than 50%. After post-ozonation, the desired removal was achieved at a 1.5 mg L−1 dosage with all the odorants decreased below the corresponding odor threshold concentrations (OTCs) in the effluents. Furthermore, at a 1 mg L−1 post-ozone addition, by combining with subsequent GAC process, the odor problem was solved as well. Conclusion: To resolve the odor problem in the drinking water, the concentrations of the odorants at less than their OTCs need to be achieved. As 2-MIB and BCIE have low reactivity towards direct ozonation, a subsequent GAC is needed with a moderate dosage of post-ozonation (1 mg L−1). Thus, for the odor problem in the source water, the suggested operation is: 1 mg L−1 of pre-ozonation in combination with coagulation, sedimentation, and sand filtration, followed by a 1 mg L−1 dosage of post-ozonation and finished by a GAC process. [ABSTRACT FROM AUTHOR]

Background: Although listed in the Stockholm Convention, commercial Decabromodiphenyl ether (c-DecaBDE) is still being produced in many factories and used as a kind of flame retardants primarily in plastic polymers and textiles. Widespread use offered many exposure ways of its major ingredient, BDE-209, to humans and the environment. Most current studies of BDE-209 focused on the health effects and toxicity of thyroid disruption, oxidative stress, neurotoxicity, and reproductive function, but seldom spread light on the relationship between neurobehavioral toxicity and visual dysfunction. Using zebrafish larvae model, we hope to uncover the potential relationship between the neurobehavioral and visual effects after exposure to BDE-209. Results: BDE-209 exposure could not induce the changes of locomotion and path angle in 5 days post fertilization (dpf) larvae; however, 5 μg/L BDE-209 exposure caused locomotor hyperactivity and more responsive turns at 7 dpf. The social activity of 50 μg/L exposure group was significantly higher than the control group at 6 dpf. Besides, 5 and 50 μg/L exposure caused the upregulation and downregulation of four cone opsin genes, respectively. The expression of rhodopsin gene was not influenced by both concentration exposures. Conclusion: The neurobehavioral effects induced by 5 μg/L BDE-209 exposure were consistent with the upregulation of four cone opsins in 7 dpf larvae. The low concentration of BDE-209 exposure caused the hyperactivity and more responsive turns of larvae possibly contributing to the disruption on the cone opsin expressions of larvae. Our results would provide the mechanism cue of neurobehavioral toxicity after BDE-209 exposure and call for more attention on the ecotoxicology studies of BDE-209. [ABSTRACT FROM AUTHOR]

The pollution of toxic and persistent heavy metals commonly exist in water environment; such multi-component pollutants pose a serious threat to human beings and other organisms. Herein, to make full use of the advantages of both layered double hydroxide (LDH) and rice husk ash (RHA), a novel Mg-Fe-LDH-RHA functional material was synthesized by assembling LDH on the biochar derived from RHA and used as an adsorbent for removal of heavy metal ions including Pb2+, Cu2+, Co2+, Ni2+, Zn2+, and Cd2+. The adsorption kinetics and isotherms of heavy metal ions in a mono-component system, the adsorption capacities in mixed multi-metal ion system, and the regeneration of the adsorbent were studied in detail. The results showed that the synthesized Mg-Fe-LDH-RHA might efficiently remove the above six heavy metals in water under optimized experimental conditions. Interestingly, the removal performance toward Pb(II) showed high static distribution coefficients (Kd) of ~ 107 mL/g and maximum capacity of ~ 682 mg/g. Besides, further characterizations of the adsorbent have been conducted, and the result suggested the formation of abundant functional groups including hydroxyl, carbonyl, and carboxyl groups. The removal mechanism of the metal ions might be related to ion-exchange, surface precipitation, complexation, and hydrogen binding during the interactions between the LDH-RHA material and pollutants. Such a facile and environmentally friendly approach, efficient removal performance suggests that the LDH-RHA material thus has potential for efficient removal of heavy metals in practical application. [ABSTRACT FROM AUTHOR]

Polybrominated diphenyl ethers (PBDEs), a group of potential endocrine-disrupting chemicals (EDCs) have been shown to disrupt retinoid homeostasis in different species in both laboratory and field studies. However, the molecular mechanisms of interactions with the retinoic acid receptor (RAR) are not fully understood. Zebrafish have proven useful for investigating mechanisms of chemical toxicity. In the present study, a reporter gene assay was used to investigate the activities of 11 PBDEs and six OH-PBDEs with different degrees of bromination on zebrafish RAR. All tested OH-PBDEs induced RAR transcriptional activity; however, of the 11 PBDEs examined, only BDE28 and BDE154 affected the RAR transcriptional activity. Homology modeling and molecular docking were employed to simulate the interactions of PBDEs/OH-PBDEs with zebrafish RARs and to identify binding affinities to analyze the specialization of the interaction between RARs and PBDEs/OH-PBDEs. The results showed that although these compounds could bind with RARs, the effects of PBDEs/OH-PBDEs on RAR transcriptional activity did not depend on their RAR-binding abilities. The present study is the first attempt to demonstrate that OH-PBDEs could induce RAR transcriptional activity by binding directly with RAR; these effects are possibly related to the structure of the compounds, especially their hydroxylation and bromination. Most of the PBDEs could not directly interact with the RAR. [ABSTRACT FROM AUTHOR]

Selenium (Se) has been recognized as one key to understanding mercury (Hg) exposure risks. To explore the effects of Se on Hg-induced immunotoxicity, female Balb/c mice were exposed to HgCl- or MeHgCl-contaminated drinking water (0.001, 0.01, and 0.1 mM as Hg) with coexisting NaSeO at different Se/Hg molar ratios (0:1, 1/3:1, 1:1 and 3:1). The potential immunotoxicity induced by NaSeO exposure alone (by way of drinking water) was also determined within a wide range of concentrations. After 14 days' exposure, the effects of Hg or Se on the immune system of Balb/c mice were investigated by determining the proliferation of T and B lymphocytes and the activity of natural killer cells. Hg exposure alone induced a dose-dependent suppression effect, whereas Se provided promotion effects at low exposure level (<0.01 mM) and inhibition effects at high exposure level (>0.03 mM). Under Hg and Se coexposure condition, the effects on immunotoxicity depended on the Hg species, Se/Hg ratio, and exposure concentration. At low Hg concentration (0.001 mM), greater Se ingestion exhibited stronger protective effects on Hg-induced suppression effect mainly by way of decreasing Hg concentrations in target organs. At greater Hg concentration (0.01 and 0.1 mM), immunotoxicity induced by Se (>0.03 mM) became evident, and the protective effects appeared more significant at an Se/Hg molar ratio of 1:1. The complex antagonistic effects between Se and Hg suggested that both Se/Hg molar ratio and concentration should be considered when evaluating the potential health risk of Hg-contaminated biota. [ABSTRACT FROM AUTHOR]

In the past three decades, the fast development of economy and urbanization has caused increasingly severe pollutions of urban water bodies in China. Consequently, eutrophication and deterioration of aquatic ecosystem, which is especially significant for aquatic vegetation, inevitably became a pervasive problem across the Yangtze River Basin. To rehabilitate the degraded urban water bodies, vegetation replanting is an important issue to improve water quality and to rehabilitate ecosystem. As a case study, a representative polluted urban river, Nanfeihe River, in Hefei City, Anhui Province, was chosen to be a rehabilitation target. In October 2009 and May 2010, 13 species of indigenous and prevalent macrophytes, including seven species emergent, one species floating leaved, and five species submersed macrophytes, were planted along the bank slopes and in the river. Through 1.5 years' replanting practice, the water quality and biodiversity of the river had been improved. The concentrations of total nitrogen (TN), total phosphorus (TP), and ammonia nitrogen (NH-N) declined by 46.0, 39.5, and 60.4 %, respectively. The species of macrophytes increased from 14 to 60, and the biodiversity of phytoplankton rose significantly in the river ( p < 0.05). The biomasses of zooplankton and benthos were also improved after the vegetation replanting. The study confirmed that vegetation replanting could alleviate the increasing water pollution and rehabilitate the degraded aquatic ecosystem. The case study would be an example for polluted urban waters restoration in the middle-downstream area of Yangtze River Base. [ABSTRACT FROM AUTHOR]

The Yangtze River has been a source of life and prosperity for the Chinese people for centuries and is a habitat for a remarkable variety of aquatic species. But the river suffers from huge amounts of urban sewage, agricultural effluents, and industrial wastewater as well as ship navigation wastes along its course. With respect to the vast amounts of water and sediments discharged by the Yangtze River, it is reasonable to ask whether the pollution problem may be solved by simple dilution. This article reviews the past two decades of published research on organic pollutants in the Yangtze River and several adjacent water bodies connected to the main stream, according to a holistic approach. Organic pollutant levels and potential effects of water and sediments on wildlife and humans, measured in vitro, in vivo, and in situ, were critically reviewed. The contamination with organic pollutants, including polycyclic aromatic hydrocarbons, polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polychlorinated dibenzo- p-dioxins/polychlorinated dibenzofurans, polybrominated diphenyl ethers (PBDEs), perfluorinated compounds (PFCs), and others, of water and sediment along the river was described. Especially Wuhan section and the Yangtze Estuary exhibited stronger pollution than other sections. Bioassays, displaying predominantly the endpoints mutagenicity and endocrine disruption, applied at sediments, drinking water, and surface water indicated a potential health risk in several areas. Aquatic organisms exhibited detectable concentrations of toxic compounds like PCBs, OCPs, PBDEs, and PFCs. Genotoxic effects could also be assessed in situ in fish. To summarize, it can be stated that dilution reduces the ecotoxicological risk in the Yangtze River, but does not eliminate it. Keeping in mind an approximately 14 times greater water discharge compared to the major European river Rhine, the absolute pollution mass transfer of the Yangtze River is of severe concern for the environmental quality of its estuary and the East China Sea. Based on the review, further research needs have been identified. [ABSTRACT FROM AUTHOR]

Bicarbonate plays a crucial role in limiting the growth of submersed aquatic macrophytes in eutrophic lakes, and high ammonia is often toxic to macrophytes. In order to evaluate the combined effect of HCO and total ammonia (i.e., the total of NH and NH) on submersed macrophytes Vallisneria natans, the growth and physiological response of V. natans in the presence of HCO and ammonia were studied. The results showed that with the increase of ammonia, morphological parameters of V. natans declined. In contrast, increased HCO concentration stimulated the growth of V. natans, especially when the NH-N/NO-N ratio was 1:7. High ammonia concentration induced excess free amino acids (FAA) accumulation and soluble carbohydrates (SC) depletion in plant tissues. However, the elevated HCO promoted the synthesis of SC and rendered the decrease of FAA/SC ratio. The results also suggested that HCO could partially alleviate the stress of ammonia, as evidenced by the decrease of FAA/SC ratio and the growth enhancement of V. natans when the ammonia concentration was 0.58 mg L. Given the fact that HCO is probably the dominant available carbon source in most eutrophic lakes, the ability of V. natans to use HCO for SC synthesis may explain the alleviating effect of HCO on V. natans under ammonia stress. [ABSTRACT FROM AUTHOR]

As organisms are typically exposed to chemical mixtures over long periods of time, chronic mixture toxicity is the best way to perform an environmental risk assessment (ERA). However, it is difficult to obtain the chronic mixture toxicity data due to the high expense and the complexity of the data acquisition method. Therefore, an approach was proposed in this study to predict chronic mixture toxicity. The acute (15 min exposure) and chronic (24 h exposure) toxicity of eight antibiotics and trimethoprim to Vibrio fischeri were determined in both single and binary mixtures. The results indicated that the risk quotients (RQs) of antibiotics should be based on the chronic mixture toxicity. To predict the chronic mixture toxicity, a docking-based receptor library of antibiotics and the receptor-library-based quantitative structure-activity relationship (QSAR) model were developed. Application of the developed QSAR model to the ERA of antibiotic mixtures demonstrated that there was a close affinity between RQs based on the observed chronic toxicity and the corresponding RQs based on the predicted data. The average coefficients of variations were 46.26 and 34.93 % and the determination coefficients ( R) were 0.999 and 0.998 for the low concentration group and the high concentration group, respectively. This result convinced us that the receptor library would be a promising tool for predicting the chronic mixture toxicity of antibiotics and that it can be further applied in ERA. [ABSTRACT FROM AUTHOR]

The reduction of hexavalent chromium by scrap iron was investigated in continuous long-term fixed bed system. The effects of pH, empty bed contact time (EBCT), and initial Cr(VI) concentration on Cr(VI) reduction were studied. The results showed that the pH, EBCT, and initial Cr(VI) concentration significantly affected the reduction capacity of scrap iron. The reduction capacity of scrap iron were 4.56, 1.51, and 0.57 mg Cr(VI)·g Fe at pH 3, 5, and 7 (initial Cr(VI) concentration 4 mg·L, EBCT 2 min, and temperature 25°C), 0.51, 1.51, and 2.85 mg Cr(VI)·g Fe at EBCTs of 0.5, 2.0, and 6.0 min (initial Cr(VI) concentration 4mg·L, pH 5, and temperature 25°C), and 2.99, 1.51, and 1.01 mg Cr(VI)·g Fe at influent concentrations of 1, 4, and 8 mg·L (EBCT 2 min, pH 5, and temperature 25°C), respectively. Fe(total) concentration in the column effluent continuously decreased in time, due to a decrease in time of the iron corrosion rate. The fixed bed reactor can be readily used for the treatment of drinking water containing low amounts of Cr(VI) ions, although the hardness and humic acid in water may shorten the lifetime of the reactor, the reduction capacity of scrap iron still achieved 1.98 mg Cr·g Fe. Scanning electron microscope equipped with energy dispersion spectrometer and X-ray diffraction were conducted to examine the surface species of the scrap iron before and after its use. In addition to iron oxides and hydroxide species, iron-chromium complex was also observed on the reacted scrap iron. [ABSTRACT FROM AUTHOR]

Although environmental contaminants are usually encountered as nonequitoxic mixtures, most studies have investigated the toxicity of equitoxic mixtures. In the present study, a method for prediction of the toxicity of nonequitoxic mixtures was developed using the similarity parameter (λ). The joint effect of multiple contaminants at the median inhibition concentration in equitoxic ( $$ {\text{TU}}_{\text{sum-50}}^{\text{equitoxic}} $$) and nonequitoxic ( $$ {\text{TU}}_{\text{sum-50}}^{\text{nonequitoxic}} $$) binary, ternary, and quaternary mixtures was investigated using Vibrio fischeri. The observed results indicate that the concentration ratios of individual chemicals in the mixtures influenced the joint effects, and that λ could be employed to evaluate the relation between $$ {\text{TU}}_{\text{sum-50}}^{\text{equitoxic}} $$ and $$ {\text{TU}}_{\text{sum-50}}^{\text{nonequitoxic}} $$. Prediction models for the joint effects of nonequitoxic ( $$ {\text{TU}}_{\text{sum-50}}^{\text{nonequitoxic}} $$) mixtures were derived from a combination of $$ {\text{TU}}_{\text{sum-50}}^{\text{equitoxic}} $$ and λ. The predictive capabilities of these models were validated by comparing the predicted data with the observed data for binary, ternary, and quaternary mixtures. The prediction models have promising applications in controlling environmental pollution, evaluating drug interactions, and optimizing combinations of pesticides used in agriculture. [ABSTRACT FROM AUTHOR]

In this study, a total of 40 tests of the toxicity of 8 halogenated benzenes to five algal species were performed. The result demonstrated that the toxicity of halogenated benzenes to five algal species was directly related to the hydrophobicity of the chemicals and the lipid content of the algae. Based on the results, we developed a K-based quantitative structure-activity relationship (QSAR) model: log(1/EC) = 1.050log K + 1.429log(1/ lipid)−3.224 with n = 40, r = 0.946, S.E. = 0.211, F = 323.933 at p < 0.001. This model provides evidence that the toxicity of halogenated benzenes to these five algae tested is related to the slower transference into lipid. This model can potentially be generalized to other algal species and toxicants. [ABSTRACT FROM AUTHOR]

ute toxicity (EC) and chronic toxicity (EC) of 21 antibiotics on Photobacterium phosphoreum was observed and Quantitative structure-activity relationship (QSAR) models were developed, respectively. By comparing these two QSAR models, the following model was established, log(1/EC) = 1.8283 + 1.1503log(1/EC) + 0.2872Elomo − 0.0901DM + 0.0003PMIZ + 0.0088PSA − 0.0382SD, r = 0.8513, where Elomo is lowest occupied molecular energy, DM is dipole moment, PMIZ is principal moment of inertia Z, PSA is polar surface area, and SD is sum of degrees. It provides a good way for us to obtain EC from EC, because the later is far easier to observe than the former. [ABSTRACT FROM AUTHOR]

Particular non-monotonic dose-response curves of many endocrine disrupting chemicals (EDCs) suggest the existence of diverse toxicity mechanisms at different dose levels. As a result, the biological activities of EDCs cannot be simply exhibited by unique EC50/LD50 values, and the quantitative structure-activity relationship (OSAR) analysis for non-monotonic dose-response relationship becomes an unknown field in the environmental science. In this paper, nine phenols with inverted U-shaped dose-response curves in lymphocyte proliferation test of Carassius auratus were selected. The binding interactions between the phenols and several typical EDCs-related receptors were then explored in a molecular simulation study. The estrogen receptor (ER), androgen receptor (AR), thyroid hormone receptor (TR), bacterial O2 sensing FixL protein (FixL), aryl hydrocarbon receptor (AhR), and the peroxisome proliferator-activated receptor (PPAR) were the target receptors in the study. Linear regression QSAR models for the low and high exposure levels of the compounds were developed separately. The results indicated that the lymphocyte proliferation in the low-dose range might involve ER-mediated process, while the proliferation inhibition in the high dose range was dominated by the acute toxicity of phenols due to receptor occupancy and cell damage. [ABSTRACT FROM AUTHOR]

In this study, the toxicity of 49 mixed halogenated benzenes to Dicrateria zhanjiangensis was determined and the partition coefficient of these mixtures was described by using the C18-EmporeTM disks/water partition coefficient ( K mix). According to these data, a simple K mix-based QSAR model was successfully used to correlate the toxicity of the mixed halogenated benzenes to D. zhanjiangensis. [ABSTRACT FROM AUTHOR]

In this study, PCR-denaturing gradient gel electrophoresis (DGGE) was applied to analyze the microbial communities in lake sediments from Lake Xuanwu, Lake Mochou in Nanjing and Lake Taihu in Wuxi. Sediment samples from seven locations in three lakes were collected and their genomic DNAs were extracted. The DNA yields of the sediments of Lake Xuanwu and Lake Mochou were high (10 μg/g), while that of sediments in Lake Taihu was relatively low. After DNA purification, the 16S rDNA genes (V3 to V5 region) were amplified and the amplified DNA fragments were separated by parallel DGGE. The DGGE profiles showed that there were five common bands in all the lake sediment samples indicating that there were similarities among the populations of microorganisms in all the lake sediments. The DGGE profiles of Lake Xuanwu and Lake Mochou were similar and about 20 types of microorganisms were identified in the sediment samples of both lakes. These results suggest that the sediment samples of these two city lakes (Xuanwu, Mochou) have similar microbial communities. However, the DGGE profiles of sediment samples in Lake Taihu were significantly different from these two lakes. Furthermore, the DGGE profiles of sediment samples in different locations in Lake Taihu were also different, suggesting that the microbial communities in Lake Taihu are more diversified than those in Lake Xuanwu and Lake Mochou. The differences in microbial diversity may be caused by the different environmental conditions, such as redox potential, pH, and the concentrations of organic matters. Seven major bands of 16S rDNA genes fragments from the DGGE profiles of sediment samples were further re-amplified and sequenced. The results of sequencing analysis indicate that five sequences shared 99%–100% homology with known sequences ( Bacillus and Brevibacillus, uncultured bacteria), while the other two sequences shared 93%–96% homology with known sequences ( Acinetobacter, and Bacillus). The study shows that the PCR-DGGE technique combined with sequence analysis is a feasible and efficient method for the determination of microbial communities in sediment samples. [ABSTRACT FROM AUTHOR]

Nitroaromatics are typical toxic organic pollutants and are ubiquitous in environment with diverse structures. They are widely used in many industries and formed during many natural and anthropogenic processes. Most of these pollutants are potentially carcinogenic and the assessment and prediction of the mutagenicity of nitroaromatics are of great interest. In this paper the structure-mutagenicity relationships of 219 nitroaromatics are investigated by molecular orbital theory based classic structure-activity relationships and comparative molecular field analysis (CoMFA). A comparison is undertaken in respect of the interpretation of mechanism and predictive ability for these two categories of QSAR approaches and highly predictive QSAR models have been developed. [ABSTRACT FROM AUTHOR]

Experimental and epidemiological studies suggest that some man-made and naturally occurring chemicals related to the environment have the potential to interrupt normal functioning of the endocrine systems of humans and wildlife. These chemicals, termed EDCs (Endocrine disrupting Chemicals), pose serious threats to the reproductive capability of humans and wildlife. Because of the structural diversity and various types, development of structure-based rapid screening methodologies is important and necessary for the assessment of the environmental pollutants. In this paper molecular hologram based QSAR models were developed with the combinatory application of partial least square (PLS) regression for a large diverse set of 105 environmental estrogens. Quantitatively predictive models were developed based on only molecular structures, which can be used for the accurate prediction of estrogenicity to rapidly screen potential environmental endocrine disrupting chemicals. [ABSTRACT FROM AUTHOR]

Background: Atmosphere is one of the sources and sinks to gas- and particle-bound brominated flame retardants (BFRs). Therefore, BFRs can enter human body via inhalation. In the present study, 79 of gas- and particle-phase samples (TSP, PM10 and PM2.5) were collected during 2015–2016 in urban area of Shanghai, China to investigate the occurrence of 25 polybrominated diphenyl ether (PBDEs) congeners, hexabromobenzene (HBB) and 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE). Results: The total concentrations of BFRs ranged from 0.66 to 13.7 pg/m3, 25.82 to 376.27 pg/m3, 14.58 to 365.49 pg/m3 and 15.17 to 304.89 pg/m3 in gas, TSP, PM10 and PM2.5, respectively. HBB was the main compound in gas phase; while BDE-209 was the dominant congener in particle phase. Atmospheric BFRs in winter was much lower than in summer, while particle phase showed opposite seasonal tendency. Conclusions: Clausius–Clapeyron equation suggested that BTBPE, BDE-28, -66, -99, -100, and -154 were more driven by temperature and evaporated from local contamination. Higher-brominated congeners tended to be absorbed in particle phase, while low-brominated compounds partitioned in both gas and particle phases. Gas/particle partitioning results showed that absorption into the aerosol organic matter was the dominant process for BFRs. The inhalation health risk assessment demonstrated that the hazard quotient (HQs) for most PBDEs in winter was higher than in summer. [ABSTRACT FROM AUTHOR]

Background: Novel brominated flame retardants (NBFRs) have been increasingly used as alternatives to legacy BFRs (e.g., PBDEs and HBCDs) in consumer products, but are liable to emigrate and contaminate indoor dust. In this study, a total of 154 house dust samples including floor dust (FD) and elevated surface dust (ESD) were collected in the biggest metropolitan area (Shanghai) of East China in 2016. Limited information about temporal variation of NBFRs indoors is available, while the period of sampling is influential in human exposure estimates. Levels, temporal variation, and human exposure of seven target NBFRs such as decabromodiphenylethane (DBDPE), 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), 2-ethylhexyl 2,3,4,5-tetrabromobenzoate (EHTBB), and bis(2-ethylhexyl) tetrabromophthalate (BEHTEBP) were investigated in indoor house dust.Results: Concentrations of ∑7NBFRs ranged from 19.11 to 3099 ng/g with a geomean of 295.1 ng/g in FD, and from 34.74 to 404.6 ng/g with a geomean of 117.9 ng/g in ESD. The geomeans of DBDPE were 219.6 ng/g in FD and 76.89 ng/g in ESD, accounting for 90.5% and 80.5% of ∑7NBFRs. Levels of EHTBB, BTBPE, and DBDPE in FD exceeded significantly those in ESD. The temporal variation in ∑7NBFRs in FD was ranked as summer > winter > autumn > spring. The daily exposure doses (DEDs) of ∑7NBFRs via dust ingestion decreased as: infants > toddlers > children > teenagers > adults. Infants showed the highest DED in FD, 9.1 ng/kg bw/day.Conclusions: DBDPE clearly dominated the NBFRs in both FD and ESD, but the concentrations of DBDPE in this study were generally moderate compared with the other international studies. Dust ingestion was the major pathway of human exposure to NBFRs indoors. About eightfold difference in exposure estimates between infants and adults showed that infants faced elevated exposure risks in FD. This study highlighted the necessity to estimate human exposure of NBFRs for different age groups using FD and ESD, respectively. [ABSTRACT FROM AUTHOR]

Haloacetamides (HAcAms), an emerging class of nitrogenous disinfection by-products (N-DBPs) of health concern, have been frequently identified in drinking waters. It has long been appreciated that free amino acids (AAs), accounting for a small fraction of the dissolved organic nitrogen (DON) pool, can form dichloroacetamide (DCAcAm) during chlorination. However, the information regarding the impacts of combined AAs, which contribute to the greatest identifiable DON portion in natural waters, is limited. In this study, we compared the formation of HAcAms from free AAs (tyrosine [Tyr] and alanine [Ala]) and combined AAs (Tyr-Ala, Ala-Tyr, Tyr-Tyr-Tyr, Ala-Ala-Ala), and found that HAcAm formation from the chlorination of AAs in combined forms (oligopeptides) significantly exhibited a different pattern with HAcAm formation from free AAs. Due to the presence of peptide bonds in tripeptides, Tyr-Tyr-Tyr and Ala-Ala-Ala produced trichloroacetamide (TCAcAm) in which free AAs was unable to form TCAcAm during chlorination. Moreover, peptide bond in tripeptides formed more tri-HAcAms than di-HAcAms in the presence of bromide. Therefore, the peptide bond may be an important indicator to predict the formation of specific N-DBPs in chlorination. The increased use of algal- and wastewater-impacted water as drinking water sources will increase health concerns over exposure to HAcAms in drinking water. [ABSTRACT FROM AUTHOR]