Search

Triphenyl phosphate (TPHP) and tris(1.3-dichloroisopropyl) phosphate (TDCIPP) are emerging contaminants that pervade diverse ecosystems and impair the thyroid and neural signaling pathways. The intricate interactions between thyroid and neurodevelopmental effects mediated by TPHP and TDCIPP remain elusive. This study integrates in vivo, in vitro, and in silico approaches to elucidate these mechanisms in Cyprinus carpio at varying temperatures. It showed that TPHP and TDCIPP hindered fish growth, particularly at low temperatures, by interfering with thyroid hormone synthesis and transport processes. Both compounds have been identified as environmental hormones that mimic thyroid hormone activity and potentially inhibit acetylcholinesterase, leading to neurodevelopmental disorders characterized by brain tissue damage and disrupted cholinergic synapses, such as axon guidance and regeneration. Notably, the bioaccumulation of TPHP was 881.54 % higher than that of TDCIPP, exhibiting temperature-dependent variations with higher levels of TDCIPP at low temperatures (20.50 % and 250.84 % above optimum and high temperatures, respectively), suggesting that temperature could exacerbate the toxicity effects of OPEs. This study sheds new light on the mechanisms underlying thyroid endocrine disruption and neurodevelopmental toxicity in C. carpio. More importantly, these findings indicate that temperature affects the environmental fate and effects of TPHP and TDCIPP, which could provide an important basis for ecological environmental zoning control of emerging contaminants in the future., Competing Interests: Declaration of Competing Interest The authors declare that there are no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

With increasing urbanization and rapid industrialization, more and more environmental problems have arisen. Phthalates (PAEs) are the foremost and most widespread plasticizers and are readily emitted from these manufactured products into the environment. PAEs act as endocrine-disrupting chemicals (EDCs) and can have serious impacts on aquatic organisms as well as human health. In this study, the water quality criteria (WQC) of five PAEs (dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), butyl benzyl phthalate (BBP) and di(2-ethylhexyl) phthalate (DEHP)) for freshwater aquatic organisms were developed using a species sensitivity distribution (SSD) and a toxicity percentage ranking (TPR) approach. The results showed that long-term water quality criteria (LWQC) of PAEs using the SSD method could be 13.7, 11.1, 2.8, 7.8, and 0.53 μg/L, respectively. Criteria continuous concentrations (CCC) of PAEs were derived using the TPR method and determined to be 28.4, 13.1, 1.3, 2.5, and 1.6 μg/L, respectively. The five PAEs are commonly measured in China surface waters at concentrations between ng/L and μg/L. DBP, DEHP, and di-n-octyl phthalate (DnOP) were the most frequently detected PAEs, with occurrence rates ranging from 67% to 100%. The ecological risk assessment results of PAEs showed a decreasing order of risk at the national level, DEHP, DBP, DMP, DEP, DnOP. The results of this study will be of great benefit to China and other countries in revising water quality standards for the conservation of aquatic species., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Organophosphate esters (OPEs) have been widely used as flame retardants and plasticizers in consumer and industrial products. They have been found to have numerous exposure hazards. Recently, several OPEs have been detected in surface waters around the world, which may pose potential ecological risks to freshwater organisms. In this study, the concentration, spatial variation, and ecological risk of 15 OPEs in the Beiyun and Yongding rivers were unprecedentedly investigated by the ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and risk quotient (RQ) method. The result showed that triethyl phosphate (TEP), tri (2-chloroisopropyl) phosphate (TCPP) were the most abundant OPEs with average concentrations of 55.53 ng/L and 42.29 ng/L, respectively. The concentrations of OPEs in the Beiyun River are higher than in the Yongding River, and their levels were higher in densely populated and industrial areas. The risk assessment showed that there was insignificant from OPEs to freshwater organisms in these rivers (RQs <0.1). The risk was higher downstream than upstream, which was related to human-intensive industrial activities downstream in the Yongding River. The ecological risk of OPEs in surface waters worldwide was estimated by joint probability curves (JPCs), and the result showed that there was a moderate risk for tri (2-chloroethyl) phosphate (TCEP), a low risk for trimethyl phosphate (TMP), and insignificant for other OPEs. In addition, the QSAR-ICE-SSD model was used to calculate the hazardous concentration for 5% (HC 5 ). This result validated the feasibility and accuracy of this model in predicting acute data of OPEs and reducing biological experiments on the toxicity of OPEs. These results revealed the ecological risk of OPEs and provided the scientific basis for environmental managers., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Due to their endocrine-disrupting effects and the risks posed in surface waters, in particular by chronic low-dose exposure to aquatic organisms, phthalate esters (PAEs) have received significant attention. However, most assessments of risks posed by PAEs were performed at a selection level, and thus limited by empirical data on toxic effects and potencies. A quantitative structure activity relationship (QSAR) and interspecies correlation estimation (ICE) model was constructed to estimate hazardous concentrations (HCs) of selected PAEs to aquatic organisms, then they were used to conduct a multiple-level environmental risk assessment for PAEs in surface waters of China. Values of hazardous concentration for 5% of species (HC 5 s), based on acute lethality, estimated by use of the QSAR-ICE model were within 1.25-fold of HC 5 values derived from empirical data on toxic potency, indicating that the QSAR-ICE model predicts the toxicity of these three PAEs with sufficient accuracy. The five selected PAEs may be commonly measured in China surface waters at concentrations between ng/L and μg/L. Risk quotients according to median concentrations of the five PAEs ranged from 3.24 for di(2-ethylhexhyl) phthalate (DEHP) to 4.10 × 10 -3 for dimethyl phthalate (DMP). DEHP and dibutyl phthalate (DBP) had risks to the most vulnerable aquatic biota, with the frequency of exceedances of the predicted no-effect concentration (PNECs) of 75.5% and 38.0%, respectively. DEHP and DBP were identified as having "high" or "moderate" risks. Results of the joint probability curves (JPC) method indicated DEHP posed "intermediate" risk to freshwater species with a maximum risk product of 5.98%. The multiple level system introduced in this study can be used to prioritize chemicals and other new pollutant in the aquatic ecological., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Copper (Cu) exists in a variety of forms in different aquatic environments, and affects their bioavailability. In this study we provide a systematic review on toxicity of Cu which focuses on identifying evidence in the mechanisms of Cu toxicity, and apply an adverse outcome pathway (AOP) analysis to identify multiple potential mechanisms and their interactions of Cu toxicity to fish. This analysis process included the mechanisms of behavior toxicant, oxidative toxicant, ion regulation disruption toxicity, as well as endocrine disruption toxicity. It was found that at low levels of Cu exposure, swimming, avoid predators, locating prey and other sensory functions will be impaired, and the organism will suffer from metabolic alkalosis and respiratory acidosis following the inhibition of the carbonic anhydrase active. The main pathway of acute toxicity of Cu to fish is the inhibition of the Na + /K + -ATPase enzyme, and lead to reduced intracellular sodium absorption, as well as Cu-induced increased cell permeability, in turn resulting in increased sodium ion loss, leading to cardiovascular collapse and respiratory insufficiency. The endocrine disruption toxicity of Cu to fish caused growth inhibition and reproductive reduction. In addition, there are several key pathways of Cu toxicity that are affected by hardness (e.g., Ca 2+ ) and intracellular DOC concentrations, including inhibiting Cu-induction, improving branchial gas exchange, altering membrane transport functions, decreasing Na + loss, and increasing Na + uptake. The results of the AOP analysis will provide a robust framework for future directed research on the mechanisms of Cu toxicity., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022. Published by Elsevier B.V.)

The chloride in water frequently exceeds the standard; directly quoting foreign water-quality criteria (WQC) or standards will inevitably reduce the scientific value of the water-quality standard (WQS) in China. Additionally, this may lead to the under- or overprotection of water bodies. This study summarized the sources, distribution, pollution status, and hazards of chloride in China's water bodies. Additionally, we compared and analyzed the basis for setting WQS limits for chloride in China; we systematically analyzed the basis for setting the WQC for chloride in foreign countries, especially the United States. Finally, we collected and screened data on the toxicity of chloride to aquatic organisms; we also used the species sensitivity distribution (SSD) method to derive the WQC value for chloride, which is 187.5 mg·L -1 . We put forward a recommended value for freshwater WQS for chloride in China: less than 200 mg·L -1 . The study of a freshwater WQC for chloride is not only a key point of environmental research, but also an urgent demand to ensure water ecological protection in China. The results of this study are of great significance for the environmental management of chloride, protection of aquatic organisms, and risk assessment, especially for the revision of WQSs.

Alkylphenols (APs) are ubiquitous and generally present in higher residue levels in the environment. The present work focuses on the development of a set of in silico models to predict the aquatic toxicity of APs with incomplete/unknown toxicity data in aquatic environments. To achieve this, a QSAR-ICE-SSD model was constructed for aquatic organisms by combining quantitative structure-activity relationship (QSAR), interspecies correlation estimation (ICE), and species sensitivity distribution (SSD) models in order to obtain the hazardous concentrations (HCs) of selected APs. The research indicated that the keywords "alkylphenol" and "nonylphenol" were most commonly studied. The selected ICE models were robust (R 2 : 0.70-0.99; p-value < 0.01). All models had a high reliability cross- validation success rates (>75%), and the HC 5 predicted with the QSAR-ICE-SSD model was 2-fold than that derived with measured experimental data. The HC 5 values demonstrated nearly linear decreasing trend from 2-MP to 4-HTP, while the decreasing trend from 4-HTP to 4-DP became shallower, indicates that the toxicity of APs to aquatic organisms increases with the addition of alkyl carbon chain lengths. The ecological risks assessment (ERA) of APs revealed that aquatic organisms were at risk from exposure to 4-NP at most river stations (the highest risk quotient (RQ) = 1.51), with the highest relative risk associated with 2.9% of 4-NP detected in 82.9% of the sampling sites. The targeted APs posed potential ecological risks in the Yongding and Beiyun River according to the mixture ERA. The potential application of QSAR-ICE-SSD models could satisfy the immediate needs for HC 5 derivations without the need for additional in vivo testing., (Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The increasing exploitation and application of rare earth elements (REEs) may induce hazardous risks to freshwater aquatic organisms. Due to the lack of water quality criteria (WQC) and sufficient reliable toxicity data, little information is available on the ecological risk of REEs in surface water. In this study, lanthanum (La) toxicity data were collected from published toxicological studies, and the data quality was assessed using a toxicological data reliability assessment tool. To obtain more toxicity data, Daphnia magna, Cyprinus carpio, and Dania rerio embryos were selected as surrogate species, and an interspecies correlation estimation (ICE) model was used to predict the toxicity of La for untested species. The species sensitivity distributions (SSDs) of La toxicity and WQC were investigated. Differences were observed in the hazardous concentrations for 5% of species (HC 5 ), but no statistically significant differences were noted in the SSD curves between the measured acute toxicity data and the predicted data. For the SSDs constructed from the measured toxicity data, the ICE-predicted toxicity data and all acute data supplemented with the ICE-predicted data, the acute WQC values of La were 88, 1022 and 256 μg/L, respectively. According to the SSD and corresponding HC 5 of chronic toxicity data, the chronic WQC was 14 μg/L. The results provide a scientific reference for establishing WQC for freshwater aquatic organisms and ecological risk assessments of REEs., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Water quality criteria (WQC) play an important role in the environmental management of pollutants in different countries or institutions. It has been found that endocrine disrupting chemicals (EDCs) can potentially alter functions of the endocrine system and consequently cause adverse effects in aquatic organisms. Therefore, the complicated modes of action and mechanisms of EDCs should be carefully considered in WQC studies. For example, the research regarding the WQC derivation of EDCs should prioritize sensitive aquatic species in consideration of the WQC derivation. Second, the chronic toxicity of EDCs should be of utmost concern. In addition, the appropriate effects and endpoints of EDCs should be carefully selected for the WQC derivation. Moreover, it was pointed out that some new methods should be taken into consideration in the WQC studies of EDCs in the near future., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Silver is toxic to freshwater aquatic organisms and aquatic ecosystems, and it is necessary to develop regional water quality criteria (WQC) for silver to protect the freshwater aquatic organisms in China. The toxicity database of silver for freshwater aquatic organisms involved 121 acute toxicity values for 35 species (6 phyla and 27 families) and 15 chronic toxicity values for 4 species (2 phyla and 4 families). Teleost fish showed the most sensitivity to silver after both short-term and long-term exposure. Significant correlations between the natural logarithms of hardness and the natural logarithms of acute silver toxicity were found for Daphnia magna , Oncorhynchus mykiss , and Pimephales promelas . The criterion maximum concentration (CMC) was calculated by the species sensitivity distribution method with sigmoid as the best fitting model (Adj R 2 0.9797), and the criterion continuous concentration (CCC) was obtained by the acute-to-chronic ratio method. The CMC and CCC of silver were e1.58ln(HCaCO3)-8.68, and e1.58ln(HCaCO3)-10.28 respectively, in China, with water hardness (HCaCO3, mg/L) as an independent variable. This research can provide a basis and reference for the management of silver to protect freshwater aquatic organisms in China.

Tris (1,3-dichloro-2-propyl) phosphate (TDCIPP), an alternative to brominated flame retardants, might pose an exposure risk to humans and wild animals during fetal development. Our recent study suggested that short-term TDCIPP exposure during early development caused sex-dependent behavioral alteration in adults. In the present study, multigenerational neurodevelopmental toxicity upon early-life exposure of parental zebrafish was evaluated, and the possible underlying mechanisms were further explored. Specifically, after embryonic exposure (0-10 days post-fertilization, dpf) to TDCIPP (0, 0.01, 0.10, and 1.00 μM), zebrafish larvae were cultured in clean water until the sexually matured to produce progeny (F1). The results confirmed neurodevelopmental toxicity in F1 larvae characterized by changes of developmental endpoints, reduced thigmotaxis, as well as altered transcription of genes including myelin basic protein a (mbpa), growth associated protein (gap43) and synapsin IIa (syn2a). Sex-specific changes in thyroid hormones (THs) indicated the relationship of abnormal THs levels with previously reported neurotoxicity in adult females after early-life exposure to TDCIPP. Similar changing profiles of TH levels (increased T3 and decreased T4) in adult females and F1 eggs, but not in F1 larvae, suggested that the TH disruptions were primarily inherited from the maternal fish. Further results demonstrated hypermethylation of global DNA and key genes related to TH transport including transthyretin (ttr) and solute carrier family 16 member 2 (slc16a2), which might affect the transport of THs to target tissues, thus at least partially contributing to the neurodevelopmental toxicity in F1 larvae. Overall, our results confirmed that early-life TDCIPP exposure of parental fish could affect the early neurodevelopment of F1 offspring. The underlying mechanism could involve altered TH levels inherited from maternal zebrafish and epigenetic modifications in F1 larvae., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Transition metals are widespread in aquatic environments and can be harmful when concentrations exceed thresholds. Especially for fish, an important component of the human diet, low concentrations of transition metals will directly affect their well-being. Different taxa are protected by unified water quality criteria (WQC) thresholds, which rarely consider the ecological status and economic value of different species. There is therefore an urgent need to study taxon-specific sensitivity. The present study established the species sensitivity distributions of nine typical transition metals (Cr, Mn, Fe, Ni, Cu, Zn, Ag, Cd and Hg) for protecting freshwater and seawater fish based on non-parametric kernel density estimation methods, and then derived their acute and chronic HC5-values. The results showed that Ag and Hg have the highest acute toxic potency to fish in freshwater as well as seawater. Compared with marine fish, freshwater fish were more tolerant to acute exposure to Cr, Fe, Ni and Zn, whilst being more sensitive to Ag and Cd. Moreover, edible fish are more sensitive than other fish to these metals in both freshwater and seawater, encouraging more protection of economically valuable fish that may potentially affect human health. The study provides a strong reference for future research on taxon-specific WQC for transition metals., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Heavy metals and antimicrobial resistant bacteria in livestock and poultry environments can cause declines in production and significant economic losses, leading to potential environmental and public health issues. In this study, the heavy metal pollution status of livestock breeding water bodies in the Dawen river basin of Shandong Province in China was evaluated, and a total of 10 heavy metals were measured. In addition, antimicrobial susceptibility tests were conducted for Escherichia coli strains isolated from the water samples. The results showed that among all the metals, copper, zinc, and iron were detected at each sampling point, followed by nickel (detection rate of 95.74%), arsenic (detection rate of 89.36%), selenium (detection rate of 68.09%), lead (detection rate of 27.66%), and mercury (detection rate of 12.77%). Cadmium and hexavalent chromium were not detected. The contents of nine heavy metals were below the existing water standard values in China, whereas the iron pollution index in the water body in the study area was large and may pose a potential risk. A total of 17 E. coli isolates showed different resistance to β-lactams, aminoglycosides, tetracyclines, quinolone antibiotics and chloramphenicol, but were mainly resistant to β-lactams and tetracyclines. The detection rate of the tetA resistance gene was relatively high, indicating the overuse of cephalosporins and tetracyclines. The results of the present study might provide evidence of metal pollution and theoretical basis on the treatment of colibacillosis in the livestock industries., Competing Interests: Declaration of competing interest The authors declare that there were no conflicts of interest in this research study., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Tris (2-ethylhexyl) phosphate (TEHP) is one of the most commonly used organophosphorus flame retardant (OPFR) analogues and is commonly detected in surface water and sediments. Limited information is available about the metabolic pathway or metabolite formation related to TEHP in fish. In this study, rare minnows (Gobiocyprisrarus) were exposed to TEHP in static water for 30 d to investigate the bioaccumulation and metabolite distribution in the fish muscle, liver, kidney, gill, GI-tract, ovary and testis. Based on the estimated k up , parent and k d,parent values, the bioconcentration factors (BCF parent ) of TEHP in fish tissues were calculated in the order of kidney > ovary ≈ liver ≈ testis > gill ≈ GI-tract > muscle; this finding was consistent with the results of our previous study on other alkyl-substituted OPFRs. In addition, this study identified the metabolic profiles of TEHP in the liver. TEHP was oxidatively metabolized by the fish to a dealkylated metabolite (di 2-ethylhexyl phosphate; DEHP) and hydroxylated TEHP (OH-TEHP). OH-TEHP further underwent extensive phase II metabolism to yield glucuronic acid conjugates. DEHP was mainly distributed in rare minnow in the following order: liver > GI-tract > kidney ≫ other tissues. However, the metabolite showed lower accumulation potential in fish tissues than TEHP, with metabolite parent concentration factors (MPCFs) for DEHP of less than 0.1 in all the investigated tissues. The BCF parent values of TEHP in various fish tissues were only 9.0 × 10 -3 -7.2 × 10 -4 times its estimated tissue-water partition coefficient (K tissue-water ) values based on tissue lipid, protein and water contents, which indicated the significance of biotransformation in reducing the bioaccumulation potential of TEHP in fish. The toxicokinetic data in the present study help in understanding the tissue-specific bioaccumulation and metabolism pathways of TEHP in fish and highlight the importance of toxicology research on TEHP metabolites in aquatic organisms., Competing Interests: Declaration of competing interest The authors declared that they have no conflicts of interest to this work entitled “Tissue-specific bioaccumulation, metabolism and excretion of tris(2-ethylhexyl) phosphate (TEHP) in rare minnow (Gobiocypris rarus)” by Rui Hou, Yiping Xu, Kaifeng Rao, Chenglian Feng, and Zijian Wang for publication in the Environmental Pollution., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Interest in the risks posed by trace concentrations of pharmaceuticals and personal care products (PPCPs) in surface waters is increasing, particularly with regard to potential effects of long-term, low-dose exposures of aquatic organisms. In most cases, the actual studies on PPCPs were risk assessments at screening-level, and accurate estimates were scarce. In this study, exposure and ecotoxicity data of 50 PPCPs were collected based on our previous studies, and a multiple-level environmental risk assessment was performed. The 50 selected PPCPs are likely to be frequently detected in surface waters of China, with concentrations ranging from the ng L -1 to the low-g L -1 , and the risk quotients based on median concentrations ranged from 2046 for nonylphenol to 0 for phantolide. A semi-probabilistic approach screened 33 PPCPs that posed potential risks to aquatic organisms, among which 15 chemicals (nonylphenol, sulfamethoxazole, di (2-ethylhexyl) phthalate, 17β-ethynyl estradiol, caffeine, tetracycline, 17β-estradiol, estrone, dibutyl phthalate, ibuprofen, carbamazepine, tonalide, galaxolide, triclosan, and bisphenol A) were categorized as priority compounds according to an optimized risk assessment, and then the refined probabilistic risk assessment indicated 12 of them posed low to high risk to aquatic ecosystem, with the maximum risk products ranged from 1.54% to 17.38%. Based on these results, we propose that the optimized risk assessment was appropriate for screening priority contaminants at national scale, and when a more accurate estimation is required, the refined probability risk assessment is useful. The methodology and process might provide reference for other research of chemical evaluation and management for rivers, lakes, and sea waters., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2019 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Benzene homologues have significant toxic effects to aquatic organisms. In this study, the acute toxicity data of benzene, toluene, ethylbenzene and xylene (BTEX) were collected and screened, and the toxicity extrapolation model of paired BTEX was established. The results showed that except the correlation between benzene and xylene was not strong due to insufficient data, the linear correlation of the other five paired BTEX was good (p < 0.01), and R 2 fitted by the four out of five paired BTEX was greater than 0.85. The cross validation showed that ethylbenzene-xylene model was optimal, and for most species (81.8%), the established five BTEX models had a prediction error of less than 10%. Also, these extrapolation models were validated by experimental results of Pseudorasbora parva. The difference between the predicted and measured values of the acute toxicity of BTEX was less than 1 fold, which indicated that the extrapolation model had high accuracy., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Copper (Cu) bioavailability varies under water conditions. In the present study, the whole life of zebrafish was divided into three different life stages (larvae, juvenile and adult) based on the growth curve, then the influences of water hardness and dissolved organic carbon (DOC) concentration on the acute toxicity of zebrafish were respectively investigated. The results indicated that the life stages had significant effects on Cu toxicity. The larvae stage was less sensitive to Cu than both the juvenile and adult stages. With the increase of water hardness, the toxicity of Cu on zebrafish was decreased, a linear relationship was observed between water hardness and Cu toxicity, and the same was true for DOC concentration. The results showed that taking the 24 days juvenile zebrafish to study the water quality criteria of Cu was stable, sensitive and economical.

In the present study, biochar particles (BPs) produced by the co-pyrolysis of sewage sludge and corncobs at temperatures of 300, 500, and 700°C were characterized. The Pb 2+ adsorption properties and the heavy metal leaching toxicity rates of the BPs were investigated. It was found that the adsorption kinetics of the Pb 2+ can be accurately described by a pseudo-second-order model, and the equilibrium adsorption data were well represented by both the Langmuir and the Freundilich Equations. The toxicity characteristic leaching procedure (TCLP) results indicated that the leaching concentrations of all the heavy metals were below the set limit of China's national standard (Identification Standard for Hazardous Waste Extraction Toxicity Identification, China National Standard, GB 5085.3-2007). The results of this study can successfully provide scientific support for future corncob treatment and sludge pollution control.

Water quality criteria are the basis for formulating environmental water quality standards, and are also an important part of environmental water protection and environmental management programs. The current study focused on a systematic discussion of the current research progress of water quality criteria theories and methodology for aquatic organisms both in China and internationally. This study also successfully pointed out key scientific issues which should be considered in the determination of water quality criteria guidelines from the following perspectives for a national strategy: the selection of pollutants; data collection and screening; species selection; water quality criteria derivation methods, and so on. For the first time, this study systematically introduced technology for the determination of water quality criteria guidelines for protecting aquatic organisms which was suitable for China's regional characteristics and national conditions. Furthermore, this study pointed out the key research directions which should be considered in the future construction of China's environmental criteria and management systems, in order to provide technical support for environmental protection and management projects., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Alkylated organophosphate esters (alkyl-OPEs) are widely used and extensively detected in aquatic organisms. This work investigated the tissue-specific toxicokinetics of two common alkyl-OPEs, tri(2‑butoxyethyl) phosphate (TBOEP) and tri‑n‑butyl phosphate (TNBP) in Chinese rare minnow (Gobiocypris rarus) through a 50 day uptake and depuration experiment. The tissue-specific bioconcentration factor (BCF) values for the two alkyl-OPEs ranged from 1 to 30 L/kg wet weight (ww), with the kidney and ovary as the tissues with the highest accumulation. The tissue BCFs only exhibited a significant correlation with lipid contents only in storage tissues (i.e., muscle, brain, ovary and testis), indicating that lipids might not be the major contributor to tissue distribution of TBOEP and TNBP. However, the contribution of blood perfusion and active transport to tissue-specific OPE accumulation needs to be further investigated. Lower accumulation of metabolites than parent chemicals was observed, with metabolite parent concentration factors (MPCFs) <1. Di-alkyl phosphate (DAP), bis(2‑butoxyethyl) phosphate (BBOEP) and di(n-butyl) phosphate (DNBP) were the most abundantly formed metabolites of TBOEP and TNBP in various tissues, followed by the monohydroxylated OPEs (OH-OPEs). However, bis(2‑butoxyethyl) hydroxyethyl phosphate (BBOEHEP), was detected at much lower levels in the tissues. All the investigated metabolites showed high production rates (k prod,metabolites ) in the fish liver, followed by the GI tract and the kidney, indicating the importance of the hepatobiliary and urinary systems in eliminating the metabolites. Our study suggested that metabolism plays an important role in eliminating these two alkyl-OPEs in rare minnow and results in different tissue distribution mechanisms for metabolites and their compounds., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Metals can pose hazards to marine species and can adversely affect structures and functions of communities of marine species. However, little is known about how structural properties of metal atoms combined with current geographical and climatic conditions affect their toxic potencies. A mathematical model, based on quantitative structure-activity relationships and species sensitivity distributions (QSAR-SSD) was developed by use of acute toxicities of six metals (Cd, Cr, Cu, Hg, Ni, and Zn) to eight marine species and accessory environmental conditions. The model was then used to predict toxicities of 31 metals and metalloids and then to investigate relationships between acute water quality criteria (WQC) and environmental conditions in coastal marine environments. The model was also used to predict WQC in the coastal areas of different countries. Given global climate change, the QSAR-SSD model allows development of WQC for metals that will be protective of marine ecosystems under various conditions related to changes in global climate. This approach could be of enormous benefit in delivering an evidence-based approach to support regulatory decision making in management of metal and metalloids in marine waters.

Transition metals in the fourth period of the periodic table of the elements are widely widespread in aquatic environments. They could often occur at certain concentrations to cause adverse effects on aquatic life and human health. Generally, parametric models are mostly used to construct species sensitivity distributions (SSDs), which result in comparison for water quality criteria (WQC) of elements in the same period or group of the periodic table might be inaccurate and the results could be biased. To address this inadequacy, the non-parametric kernel density estimation (NPKDE) with its optimal bandwidths and testing methods were developed for establishing SSDs. The NPKDE was better fit, more robustness and better predicted than conventional normal and logistic parametric density estimations for constructing SSDs and deriving acute HC5 and WQC for transition metals in the fourth period of the periodic table. The decreasing sequence of HC5 values for the transition metals in the fourth period was Ti > Mn > V > Ni > Zn > Cu > Fe > Co > Cr(VI), which were not proportional to atomic number in the periodic table, and for different metals the relatively sensitive species were also different. The results indicated that except for physical and chemical properties there are other factors affecting toxicity mechanisms of transition metals. The proposed method enriched the methodological foundation for WQC. Meanwhile, it also provided a relatively innovative, accurate approach for the WQC derivation and risk assessment of the same group and period metals in aquatic environments to support protection of aquatic organisms., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

The occurrence and distribution of target estrogenic compounds in a highly urbanized industry-impacted coastal bay were investigated, and contamination profiles were evaluated by estimating total estradiol equivalents (∑EEQs) and risk quotients (RQs). Phenolic compounds were the most abundant xenoestrogens, but seldom showed contribution to the ∑EEQs. The diethylstilbestrol (DES) and 17α-ethinylestradiol (EE2) were the major contributors followed by 17β-estradiol (E2) in comparison with a slight contribution from estrone (E1) and estriol (E3). Both ∑EEQs and RQs indicated likely adverse effects posed on resident organisms. Further, multivariate statistical method comprehensively revealed pollution status by visualized factor scores and identified multiple "hotspots" of estrogenic sources, demonstrating the presence of complex pollution risk gradients inside and particularly outside of bay area. Overall, this study favors the integrative utilization of pollution indices and factor analysis as powerful tool to scientifically diagnose the pollution characterization of human-derived chemicals for better management decisions in aquatic environments., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Over the past 20 years, global production of copper (Cu) and zinc (Zn) rank in the top three compared to other metals such as Pb, Cd, Cr, Ni, As and Hg. However, due to the potential for exposure and toxicity to humans, more attention of environmental pollution was paid to other metals such as Cd and Hg. Aquatic organisms are sensitive to Cu and Zn. Even though internal concentrations of these required elements are homeostatically controlled, toxic effects can occur at the fish gill surface. In this work, concentrations in surface waters and toxic effects of Cu, Zn, Ni, Cr, Pb, Cd, As, Hg were determined and risk of various metals in Tai Lake, China were evaluated using both risk quotients and joint probability distributions. Two transition metals, Cu and Zn posed the greatest risks to aquatic organisms while measured concentrations of other metals were less than thresholds for adverse effects. Approximately 99.9% and 50.7% of the aquatic organisms were predicted to be affected by Cu and Zn in surface water of Tai Lake respectively. Our results highlight ecological risks of Cu and Zn in water of a typical, large, urban lake in Eastern China, which was ignored in the past., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Sediments are the ultimate sink for many toxic organic contaminants released into aquatic environment. The present study evaluated the toxicity effect of 13 surface sediment samples from Huangpu River and Suzhou River, East China using two-hybrid yeast bioassays for estrogenic and thyroidal effects and H4IIE rat hepatoma cell bioassay for ethoxyresorufin O-deethylase (EROD) activity. Toxicity was expressed as 17β-estradiol equivalent (E2-EQ), 3,3',5-triiodothyronine equivalent (T3-EQ), and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalent (TEQ). At the same time, the causality between the observed EROD activity and concentrations of polycyclic aromatic hydrocarbons (PAHs) was examined. The results showed that the total estrogenic effects in sediments ranged from 0.06 to 1.21 μg E2-EQ kg(-1) dry weight (dw), the thyroidal effects ranged from 4.68 to 69.9 μg T3-EQ kg(-1) dw, and significantly positive correlations were found between lgT3-EQs and lgE2-EQs. The AhR agonist effects varied from 26.5 to 148.3 ng TEQ kg(-1) dw. Chemical analysis-derived TEQs contributed by PAHs ranged from 13.8 to 66.0 ng kg(-1) dw accounting for 27.2-109.9 % with mean of 48.9 % of TEQbio, indicating that PAHs made important contributions to the EROD effects of sediment extracts from the two rivers. The present study would provide meaningful information for further analysis and risk evaluation for organic pollutants in Huangpu River and Suzhou River.

In this study, the effect of environmental metal exposure on the accumulation and subcellular distribution of metals in the digestive gland of clams with special emphasis on metallothioneins (MTs) was investigated. Specimens of indigenous Moerella iridescens were collected from different natural habitats in Maluan Bay (China), characterized by varying levels of metal contamination. The digestive glands were excised, homogenized and six subcellular fractions were separated by differential centrifugation procedures and analyzed for their Cu, Zn, Cd and Pb contents. MTs were quantified independently by spectrophotometric measurements of thiols. Site-specific differences were observed in total metal concentrations in the tissues, correlating well with variable environmental metal concentrations and reflecting the gradient trends in metal contamination. Concentrations of the non-essential Cd and Pb were more responsive to environmental exposure gradients than were tissue concentrations of the essential metals, Cu and Zn. Subcellular partitioning profiles for Cu, Zn and Cd were relatively similar, with the heat-stable protein (HSP) fraction as the dominant metal-binding compartment, whereas for Pb this fraction was much less important. The variations in proportions and concentrations of metals in this fraction along with the metal bioaccumulation gradients suggested that the induced MTs play an important role in metal homeostasis and detoxification for M. iridescens in the metal-contaminated bay. Nevertheless, progressive accumulation of non-essential metals (Cd, and especially Pb) resulting from "spillover" was observed in putative metal- sensitive (e.g., mitochondria and heat-denaturable protein (HDP)) or lysosome/microsome fractions, demonstrating that metal detoxification was incomplete and increased the toxicological risk to M. iridescens inhabiting the metal-impacted environments. Through multiple stepwise regression analysis, the induction of MTs was statistically correlated with the HSP concentrations of Cu, and to a lesser extent with Zn, and ultimately to the Cd concentrations, exhibiting significant dose-dependent relationships. Overall, these findings not only revealed the fates of accumulated metals, but scientifically favored an improved understanding of the detoxification at the subcellular level in response to metal accumulation, supporting the focus of metabolic availability assessment on the intracellular processes or events occurring within organisms., (Copyright © 2016 Elsevier B.V. All rights reserved.)

An alternative method for species sensitivity distribution (SSD) that considers the interaction between species and the community importance is illustrated in this article. First, a food web based on the relationship between predator and prey was constructed, and the keystone indices of species were obtained based on the food web. Then, the probability density distribution of the sensitivity for each species was derived from all of the available endpoints of each species. Finally, the species sensitivity distribution for ecosystem was constructed by sampling a specific number of values from the probability density distribution of the sensitivity for each species. Data of copper toxicity to the aquatic organisms in Tai Lake were selected to derived site-specific water quality criteria (WQC). Ninety-seven endpoints of acute toxicity for 47 species and 188 endpoints of chronic toxicity for 29 species were included, and the acute and chronic WQC developed by keystone indices probabilistic species sensitivity distribution (K-PSSD) were 4.982 μg/L and 0.965 μg/L, respectively. Results showed that the aquatic organisms of Tai Lake might be underprotected. Compared with the SSD, the K-PSSD coped with the interactions between species, the community importance, and the intraspecies and interspecies variation more effectively and was better at depicting the tendency and information of raw data. The K-PSSD was especially applicable to site-specific WQC and provided an alternative or supplement to the SSD.

Due to use of different parametric models for establishing species sensitivity distributions (SSDs), comparison of water quality criteria (WQC) for metals of the same group or period in the periodic table is uncertain and results can be biased. To address this inadequacy, a new probabilistic model, based on non-parametric kernel density estimation was developed and optimal bandwidths and testing methods are proposed. Zinc (Zn), cadmium (Cd), and mercury (Hg) of group IIB of the periodic table are widespread in aquatic environments, mostly at small concentrations, but can exert detrimental effects on aquatic life and human health. With these metals as target compounds, the non-parametric kernel density estimation method and several conventional parametric density estimation methods were used to derive acute WQC of metals for protection of aquatic species in China that were compared and contrasted with WQC for other jurisdictions. HC5 values for protection of different types of species were derived for three metals by use of non-parametric kernel density estimation. The newly developed probabilistic model was superior to conventional parametric density estimations for constructing SSDs and for deriving WQC for these metals. HC5 values for the three metals were inversely proportional to atomic number, which means that the heavier atoms were more potent toxicants. The proposed method provides a novel alternative approach for developing SSDs that could have wide application prospects in deriving WQC and use in assessment of risks to ecosystems.

In the present study, yeast bioassays were used to evaluate and characterize the thyroid receptor (TR) disrupting activities of the organic extracts and elutriates of the sediments from the Guanting Reservoir, Beijing, China. An accelerated solvent extraction was used to separate the organic extracts, which were subjected to a yeast bioassay. The organic extracts could affect thyroid hormone signaling by decreasing the binding of the thyroid hormone. The TR antagonistic activity equivalents (TEQbio) referring to amiodarone hydrochloride were calculated and the observed TEQbio-organic extracts ranged from 25.4 ± 3.7 to 176.9 ± 18.0 μg/g. Elutriate toxicity tests using the modified yeast bioassay revealed that the elutriates also significantly antagonized the TR, with the TEQbio-elutriates ranging from N.D. to 7.8 ± 0.8 μg/L. To characterize the toxic compounds, elutriates were extracted by using a C18 cartridge or treated with ethylenediaminetetraacetic acid (EDTA, 30 mg/L). The results suggested that the addition of EDTA eliminated over 74.3% of the total effects, and the chemical analysis revealed that heavy metals, some of which exhibited TR disrupting potency, for example Zn and Cd, were detectable with higher concentrations in the elutriates. Thus, the cause(s) of toxicity in the elutriate appear to be partly related to the heavy metals., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Both nonparametric and parametric approaches were used to construct SSDs for use in ecological risk assessments. Based on toxicity to representative aquatic species and typical water contaminants of metals and metalloids in China, nonparametric methods based on the bootstrap were statistically superior to the parametric curve-fitting approaches. Knowing what the SSDs for each targeted species are might help in selecting efficient indicator species to use for water quality monitoring. The species evaluated herein showed sensitivity variations to different chemical treatments that were used in constructing the SSDs. For example, D. magna was more sensitive than most species to most chemical treatments, whereas D. rerio was sensitive to Hg and Pb but was tolerant to Zn. HC5 values, derived for the pollutants in this study for protecting Chinese species, differed from those published by the USEPA. Such differences may result from differences in geographical conditions and biota between China and the United States. Thus, the degree of protection desired for aquatic organisms should be formulated to fit local conditions. For approach selection, we recommend all approaches be considered and the most suitable approaches chosen. The selection should be based on the practical information needs of the researcher (viz., species composition, species sensitivity, and geological characteristics of aquatic habitats), since risk assessments usually are focused on certain substances, species, or monitoring sites. We used Tai Lake as a typical freshwater lake in China to assess the risk of metals and metalloids to the aquatic species. We calculated hazard quotients for the metals and metalloids that were found in the water of this lake. Results indicated the decreasing ecological risk of these contaminants in the following order: Hg

PCBs are typical of persistent, bioaccumulative and toxic compounds (PBTs) that are widely distributed in the environment and can biomagnify through aquatic food webs, because of their stability and lipophilic properties. Fish-eating birds are top predators in the aquatic food chain and may suffer adverse effects from exposure to PCB concentrations. In this review, we address the toxicity of PCBs to birds and have derived tissue residue guidelines (TRGs) and toxic reference values (TRVs) for PCBs for protecting birds in China. In deriving these protective indices, we utilized available data and three approaches, to wit: species sensitivity distribution (SSD), critical study approach (CSA) and toxicity percentile rank method (TPRM). The TRGs and TRVs arrived at by using these methods were 42.3, I 0. 7, 4.3 pg TEQs/g diet wm and 16.7, 15.5, and 5.5 pg TEQs/g tissue wm for the CSA SSD and TPRM approaches, respectively. These criteria values were analyzed and compared with those derived by others. The following TRG and TRY, derived by SSD, were recommended as avian criteria for protecting avian species in China: 10.7 pg TEQs/g diet wm and 15.5 pg TEQs/g tissue wm, respectively. The hazard of PCBs to birds was assessed by comparing the TRVs and TRGs derived in this study with actual PCB concentrations detected in birds or fish. The criteria values derived in this study can be used to evaluate the risk of PCBs to birds in China, and to provide indices that are more reasonable for protecting Chinese avian species. However, several sources of uncertainty exists when deriving TRGs and TRVs for the PCBs in birds, such as lack of adequate toxicity data for birds and need to use uncertainty factors. Clearly, relevant work on PCBs and birds in China are needed in the future. For example, PCB toxicity data for resident avian species in China are needed. In addition, studies are needed on the actual PCB levels in birds and fish in China. Such information is needed to serve as a more firm foundation for future risk assessments.

PBDEs are persistent organic pollutants, and have the capability to produce adverse effects on organisms. Aquatic piscivorous species at higher trophic levels have the greatest exposure risk. Information on the toxic potency of a commercial PBDE mixture, DE-71, to mink and American kestrel was reviewed, and dietary- and tissue-based TRVs were derived and evaluated for ecological risk assessment of aquatic piscivorous species inhabiting wetland areas in China. The effect on mink thyroid function was identified as the most appropriate and protective endpoint for deriving the TRV s for mammals. The TRV was based on dietary exposure, and wa s0.1 mg DE-71/kg (wm) or 0.01 mg DE-71/kg (bm)/day (ADI); for liver of mammals,the TRV was 1.2 mg LPBDEslkg (lm). For birds, reproductive effects on American kestrels were used to derive the TRVs, in which an overall UF of 3.0 was used. The TRV was based on dietary exposure, and was 0.1 mg DE-71/kg (wm) or 0.018 mg DE-71/kg (bm)/day (ADI); for eggs of birds, the TRV was 2.35 jlgLPBDEs/g (lm). Reported concentrations of PBDEs in livers of aquatic mammals found dead, and in fish and bird eggs from Chinese wetland areas were compiled and compared to the corresponding criteria values. Results indicated that TRV values reported in this study can be used as indicators for screening-level risk assessment of piscivorous species in Chinese aquatic systems. Furthermore, based on monitoring concentrations of PBDEs in fishes from two lakes (DCL and TL) in China and the dietary-based TRV of 0.1 mg DE-71/kg (wm), a screening-level risk assessment of PBDEs was performed for predatory birds and mammals. The results suggest that concentrations of PBDEs in these two areas would not be expected to cause any adverse effects on the local fish-eating wild birds and mammals.

Since in situ formation of Mg(OH)2 can efficiently sorb phosphate (PO4) from low concentrations in the environment, a novel dispersed magnesium oxide nanoflake-modified diatomite adsorbent (MOD) was developed for use in restoration of eutrophic lakes by removal of excess PO4. Various adsorption conditions, such as pH, temperature and contact time were investigated. Overall, sorption capacities increased with increasing temperature and contact time, and decreased with increasing pH. Adsorption of PO4 was well described by both the Langmuir isotherm and pseudo second-order models. Theoretical maximum sorption capacity of MOD for PO4 was 44.44-52.08 mg/g at experimental conditions. Characterization of PO4 adsorbed to MOD by use of X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and solid state (31)P nuclear magnetic resonance revealed that electrostatic attraction, surface complexation and chemical conversion in situ were the major forces in adsorption of PO4. Mg(OH)2 formed in situ had a net positive charge on the surface of the MOD that could adsorb PO4(3-) and HPO4(2-) anion to form surface complex and gradually convert to Mg3(PO4)2 and MgHPO4. Efficiency of removal of PO4 was 90% when 300 mg MOD/L was added to eutrophic lake water. Results presented here demonstrated the potential use of the MOD for restoration of eutrophic lakes by removal of excess PO4.

Lake Taihu provides vital ecological services for humans in China; it receives a great deal of attention regarding its ecological and environmental conditions. In this study, the ecological risks of eight individual polycyclic aromatic hydrocarbons (PAHs) in water were assessed using probabilistic distributions of the hazard quotient based on Monte Carlo simulation. The results show that the 95th percentile of the hazard quotients ranged from 0.00074 to 2.831, and the ecological risk of Flua was highest, followed by, in descending order of risk, B[a]P > Pyr > Ant > Phe > Flu > Ace > Chr. The probabilities of hazard quotients exceeding a decision criteria of 0.3 were 18.09%, 6.51%, 3.76%, and 2.85% for Flua, B[a]P, Pyr, and Ant, respectively, indicating their potential ecological risks to aquatic organisms. The spatial distribution of hazard quotients for these four individual PAHs with potential ecological risk were obtained using Geographic Information System (GIS), and similar spatial distribution patterns were also observed in the lake. The highest ecological risks of these four individual PAHs to aquatic organisms were found in Meiliang Bay, followed by Gonghu Bay and Xukou Bay. The uncertainty within the ecological risk assessment was also discussed.

Decabromodiphenyl ether (BDE 209), the primary component in a commonly used flame retardants, has recently been shown to be metabolized by organisms. In the present study, juvenile rainbow trout (Oncorhynchus mykiss) were exposed to BDE 209 at five nominal gradient concentrations from 50 to 1000 ng/g wet weight for 21 days via a single intraperitoneal injection. Then the liver, kidney and blood samples were collected to analyze for its debrominated, hydroxylated and methoxylated metabolites. The relationships between levels of BDE 209 metabolites in different tissues and thyroid hormone (TH) levels in plasma were evaluated. The results showed that BDE 209 could be metabolized into debrominated BDEs, methoxylated BDEs (MeO-BDEs) and hydroxylated BDEs (OH-BDEs). Levels of these three metabolites were tissue-dependent. The TH levels, including total thyroxine (TT(4)), free thyroxine (FT(4)), total triiodothyronine (TT(3)) and free triiodothyronine (FT(3)) in plasma, were significantly affected by BDE 209 metabolism. However, only FT(4) levels showed a negative correlation with MeO-BDE and OH-BDE metabolites, among which the correlation between FT(4) and OH-BDEs was the most significant., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Hydroxylated polybrominated diphenyl ethers (OH-PBDEs) have obtained increasing attention; however, few analytical methods are available for sensitive identification of these compounds in water. In this paper, we developed a highly sensitive method for simultaneous determination of nine OH-PBDEs in water by using hydrophilic-lipophilic balanced cartridge extraction, silica cartridge purification, and the combination of derivatization with liquid chromatography-electrospray tandem mass spectrometry. The effective sample pretreatment process and greatly increased instrumental sensitivity by derivatization allow for the quantification of nine OH-PBDEs at a method detection limit of 0.04-3.5 pg/L with 1-L wastewater treatment plant effluent or river water. This method was applied to wastewater effluent and river water samples collected in Beijing, China, where two OH-tetraPBDEs were detected at concentrations ranging from 0.63 to 1.0 pg/L (5-OH-BDE-47) and from 0.92 to 1.3 pg/L (6-OH-BDE-47)., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Polycyclic aromatic hydrocarbons (PAHs) are important organic contaminants with great significance for China, where coal burning is the main source of energy. In this study, concentrations, distribution between different phases, possible sources and eco-toxicological effect of PAHs of the Yangtze River were assessed. PAHs in water, suspended particulate matters (SPM) and sediment samples at seven main river sites, 23 tributary and lake sites of the Yangtze River at the Wuhan section were analyzed. The total concentrations of PAHs in the studied area ranged from 0.242 to 6.235 microg/l in waters and from 31 to 4,812 microg/kg in sediment. The average concentration of PAHs in SPM was 4,677 microg/kg, higher than that in sediment. Benzo(a)pyrene was detected only at two stations, but the concentrations were above drinking water standard. The PAHs level of the Yangtze River was similar to that of some other rivers in China but higher than some rivers in foreign countries. There existed a positive relationship between PAHs concentrations and the TOC contents in sediment. The ratio of specific PAHs indicated that PAHs mainly came from combustion process, such as coal and wood burning. PAHs may cause potential toxic effect but will not cause acute biological effects in sedimentary environment of the Wuhan section of the Yangtze River.