Ecological risk assessment of nonylphenol in coastal waters of China based on species sensitivity distribution model

Establishment of an immunoassay for detection of nonylphenols in surfactant oilfield chemicals based on computer-aided design

Nonylphenols (NPs) are confirmed endocrine disruptors that are banned in many countries due to correlations with human cancers. NPs pollution in surfactant oilfield chemicals (OFCs) has become an important environmental safety issue. It is significant to establish a simple, accurate and low-cost method for detection of NPs in OFCs. In this research, computer-aided molecular design technology was utilized to design NPs haptens. High affinity monoclonal antibodies against NPs were obtained using a matrix effect-enhanced screening method, with an IC50 value of 183.01 ng/mL. A colloidal gold immunochromatography assay (ICA) for detection of NPs enabled rapid on-site detection of large volumes of OFCs. Under optimal conditions, the limit of detection was 0.72-1.82 mg/kg, with a detection range of 4.49-191.28 mg/kg. The recovery was 84 %-104 %, with coefficients of variation < 13 %. As confirmed by high-performance liquid chromatography of natural positive OFCs samples, the proposed colloidal gold ICA demonstrated accuracy and reliability, with potential for fast and economical on field test.

A rapid and multi-endpoint ecotoxicological test using Mychonastes afer for efficient screening of metals and herbicides

Microalgal growth-based tests are international standards for ecotoxicity assessment; however, their long exposure times, large sample volumes, and reliance on a single growth-endpoint make them inadequate for rapid toxicity screening. Here, we aimed to develop a rapid and simple ecotoxicological test using the fast-growing green alga Mychonastes afer, with multiple endpoints-growth, lipid content, and photosynthesis. We exposed M. afer to two metals-silver and copper-and two herbicides-atrazine and diuron-for 24 h and identified the most sensitive and reliable endpoints for each toxicant: the maximum electron transport rate (ETRmax) for Ag, Cu and atrazine, and the lipid content for diuron. Lipid content was found to be both a sensitive and reliable biomarker, meeting the effluent limit guidelines in both the Republic of Korea and the USA. The sensitivity of M. afer to Ag and atrazine also closely matched the HC5 values derived from the species sensitivity distribution approach, confirming its reliability for setting regulatory concentrations of these contaminants. Our calculated predicted no-effect concentration (PNEC) values were similar to established European Union PNECs for Ag, Cu, atrazine, and diuron, underlining the utility of these biological endpoints for ecological risk assessment and regulatory decision making. This method required lower sample volume (2 mL vs 100 mL) and exposure time (24 h vs 72-120 h) than conventional green algal tests, and eliminated the need for labour-intensive cell counting, expensive equipment, and chlorophyll fluorescence measurement expertise. Overall, this M. afer test can be a valuable tool for the rapid screening of wastewater for metals and herbicides, contributing to environmental protection and management practices.

Assessment of potential environmental and human risks for Bisphenol AF contaminant

Bisphenol AF (BPAF) is found in high concentrations in aquatic environments due to the increased use of thermal paper and food packaging. However, there have been relatively few toxicological studies and potential risk assessments of BPAF. In this study, the risk quotient (RQ) and hazard quotient (HQ) of BPAF were derived to present the safety standards for environmental risk management and protection in lakes, rivers, bays, and Italian regions. We applied the species sensitivity distribution (SSD) method based on the previous ecotoxicological data and the results of supplementary toxicity tests on BPAF. From the SSD curves, the hazardous concentration for 5 % of the species (HC5) values for the acute and chronic toxicity data were 464.75 µg/L and 3.59 µg/L, respectively, and the acute- and chronic-based predicted no-effect concentration were derived as 154.92 µg/L and 1.20 µg/L, respectively. The acute-based RQ (RQA)values of BPAF in all regions were negligible (RQ < 0.1). The chronic-based RQ (RQC) in the Xitang River (XR) and the Central Italy (CI) showed a considerably high ecological risk (12.77 and 1.29) and the Hangzhou Bay (0.21), the South and North Italy (0.79 and 0.27), and the Tamagawa River (0.13) had a medium ecological risk (0.1 < RQ < 1.0). However, the HQ values based on the tolerable daily intake for BPAF over all age groups in these regions was < 0.1, indicating the low health risk. Nonetheless, the result of this study indicates that BPAF contamination is serious in XR and CI, and their use and emissions require continuous monitoring.

Species sensitivity distribution for nonylphenol: Acute toxicity and ecological risk in Bohai Region

Nonylphenol (NP), a main byproduct of nonylphenol polyethoxylates (NPEs) degradation, is prevalent across diverse environmental settings. Given its widespread presence, evaluating the ecological risks associated with NP in coastal waters and sediments is essential for the protection of the marine environment. This study evaluates the acute toxicity of NP on ten representative aquatic species from the Bohai Sea, determining the Aquatic Life Criteria (ALC) through two distinct methods. The Criteria Maximum Concentration (CMC) for NP in seawater was established at 12.0 μg/L, with a Predicted No-Effect Concentration (PNEC) for water at 15.2 μg/L and for sediment at 33.3 μg/kg. Additionally, a tiered ecological risk assessment (ERA) of both surface seawater and sediment in the Bohai Sea revealed significant ecological risks at various sediment sites. These results offer crucial insights for assessing the ecological risks to coastal ecosystem and provide foundational data necessary for informed environmental protection and management strategies.

Development of an effective QSAR-based hazard threshold prediction model for the ecological risk assessment of aromatic hydrocarbon compounds

The insufficient hazard thresholds of specific individual aromatic hydrocarbon compounds (AHCs) with diverse structures limit their ecological risk assessment. Thus, herein, quantitative structure-activity relationship (QSAR) models for estimating the hazard threshold of AHCs were developed based on the hazardous concentration for 5% of species (HC5) determined using the optimal species sensitivity distribution models and on the molecular descriptors calculated via the PADEL software and ORCA software. Results revealed that the optimal QSAR model, which involved eight descriptors, namely, Zagreb, GATS2m, VR3_Dzs, AATSC2s, GATS2c, ATSC2i, ω, and Vm, displayed excellent performance, as reflected by an optimal goodness of fit (R2adj = 0.918), robustness (Q2LOO = 0.869), and external prediction ability (Q2F1 = 0.760, Q2F2 = 0.782, and Q2F3 = 0.774). The hazard thresholds estimated using the optimal QSAR model were approximately close to the published water quality criteria developed by different countries and regions. The quantitative structure-toxicity relationship demonstrated that the molecular descriptors associated with electrophilicity and topological and electrotopological properties were important factors that affected the risks of AHCs. A new and reliable approach to estimate the hazard threshold of ecological risk assessment for various aromatic hydrocarbon pollutants was provided in this study, which can be widely popularised to similar contaminants with diverse structures.

A review of the pollution signatures of polycyclic aromatic hydrocarbons in the sediments of the East China Sea

Marine sediments serve as crucial reservoirs for polycyclic aromatic hydrocarbons (PAHs), and their PAH signatures offer valuable historical pollution records. This article provides a comprehensive review of the pollution status of 16 priority PAHs in more than 1000 sediments from the East China Sea (ECS). It focuses on the PAH sources, spatiotemporal distributions, driving factors, and ecological risks, with information derived from peer-reviewed papers published between 2003 and 2023. The results revealed that vehicular emissions, mixed combustion sources of coal, biomass, and coke, as well as petrogenic sources, were the primary contributors to PAH pollution in the ECS sediments, accounting for 50%, 34%, and 16%, respectively. Human activities, hydrodynamic mechanisms, and environmental variables such as particle size and organic matter, collectively influenced the distribution of PAHs. Additionally, the population size and economic development played a key role in the temporal distribution of PAHs in the ECS sediments. The ecotoxicity assessment of PAHs in sediments indicated a low risk level. These outcomes are expected to provide environmentalists with detailed and up-to-date insights into sedimentary PAHs in the ECS, helping to develop suitable monitoring plans and strategies for promoting better management of ECS environment.

Determining soil conservation strategies: Ecological risk thresholds of arsenic and the influence of soil properties

The establishment of ecological risk thresholds for arsenic (As) plays a pivotal role in developing soil conservation strategies. However, despite many studies regarding the toxicological profile of As, such thresholds varying by diverse soil properties have rarely been established. This study aims to address this gap by compiling and critically examining an extensive dataset of As toxicity data sourced from existing literature. Furthermore, to augment the existing information, experimental studies on As toxicity focusing on barley-root elongation were carried out across various soil types. The As concentrations varied from 12.01 to 437.25 mg/kg for the effective concentrations that inhibited 10% of barley-root growth (EC10). The present study applied a machine-learning approach to investigate the complex associations between the toxicity thresholds of As and diverse soil properties. The results revealed that Mn-/Fe-ox and clay content emerged as the most influential factors in predicting the EC10 contribution. Additionally, by using a species sensitivity distribution model and toxicity data from 21 different species, the hazardous concentration for x% of species (HCx) was calculated for four representative soil scenarios. The HC5 values for acidic, neutral, alkaline, and alkaline calcareous soils were 80, 47, 40, and 28 mg/kg, respectively. This study establishes an evidence-based methodology for deriving soil-specific guidance concerning As toxicity thresholds.

Improving prediction of soil heavy metal(loid) concentration by developing a combined Co-kriging and geographically and temporally weighted regression (GTWR) model

The study of heavy metal(loid) (HM) contamination in soil using extensive data obtained from published literature is an economical and convenient method. However, the uneven distribution of these data in time and space limits their direct applicability. Therefore, based on the concentration data obtained from the published literature (2000-2020), we investigated the relationship between soil HM accumulation and various anthropogenic activities, developed a hybrid model to predict soil HM concentrations, and then evaluated their ecological risks. The results demonstrated that various anthropogenic activities were the main cause of soil HM accumulation using Geographically and temporally weighted regression (GTWR) model. The hybrid Co-kriging + GTWR model, which incorporates two of the most influential auxiliary variables, can improve the accuracy and reliability of predicting HM concentrations. The predicted concentrations of eight HMs all exceeded the background values for soil environment in China. The results of the ecological risk assessment revealed that five HMs accounted for more than 90% of the area at the "High risk" level (RQ ≥ 1), with the descending order of Ni (100%) = Cu (100%) > As (98.73%) > Zn (95.50%) > Pb (94.90%). This study provides a novel approach to environmental pollution research using the published data.

Emergency response to ecological protection in maritime phenol spills: Emergency monitor, ecological risk assessment, and reduction

Recently, hundreds of maritime accidental spills of hazardous chemicals have raised public concerns, especially for phenol due to its potential of spills and highly toxicity. Therefore, for marine ecological protection, this article prepared specific strategies of emergency response to phenol spills. Through the identification for phenol behavior at sea, migration prediction, emergency monitor, as well as their new methods were reviewed. Further, ecological risk assessment and seawater quality criteria were conducted by using a species sensitivity distribution (SSD) approach, wherein, risk quotient (RQ) indicated phenol of simulated marine spills posed a high risk (RQ > 1) in 30 days. The method with eco-friendliness and high-efficiency for phenol reduction was constructed by combination of dredging equipment such as pneumatic dredgers (Airlift) and bioremediation, where marine microorganisms that degraded phenol were summarized, as well as future research needs. This study provided a guidance for emergency response and policy development of phenol spills.

Ecological risk assessment of 50 emerging contaminants in surface water of the Greater Bay Area, China

Ecological risk assessment of emerging contaminants (ECs) is an international research hotspot and is also the focus of China's "14th Five-Year Plan". The Greater Bay Area (GBA) is one of the four major bay areas in the world and the most dynamic region in China. However, there are few studies on the risk assessment of ECs in the GBA, and there needs to be a systematic and comprehensive assessment of the ecological risk of ECs. We selectively collected environmental concentration and toxicity data reported in the literature before 2022 for 50 representative ECs. We use risk quotient (RQ), semi-probability, Margin of Safety (MOS), and joint Probability curve (JPC) methods for multiple-level risk assessment. The RQ results showed that there were primary ecological risks in 20 ECs. Nine ECs were screened by the semi-probability, MOS, and JPC methods. The total risk probability of nonylphenol (NP) to the GBA was 12.11 %, and the risk to the aquatic ecological environment was the highest, followed by α-endosulfan (α-END) and erythromycin (ERY). At the same time, a comprehensive assessment method was adopted to screen the list of medium and high-risk priority pollutants in the GBA. According to the comprehensive evaluation results, although the risk is low, perfluorooctanoic acid (PFOA) still deserves widespread attention. The results showed that NP, α-END, ERY, and PFOA may be the most concerned ECs in the GBA. This research fills the gap on the ECs ecological risk assessment of the GBA and can provide a theoretical reference for managers in the follow-up of ECs regulatory governance.

Deriving seawater quality criteria of tris(2-chloroethyl) phosphate for ecological risk assessment in China seas through species sensitivity distributions

Tris(2-chloroethyl) phosphate (TCEP), one of the widely used organophosphorus flame retardants (OPFRs), has been frequently detected in the marine environment in the seas off China. The existing freshwater biotoxicity data are not suited to derivation of the seawater quality criteria of TCEP and evaluating the associated ecological risks. This study aimed at deriving water quality criteria (WQC) of TCEP for marine organisms based on species sensitivity distribution (SSD) approach using the acute toxicity data generated from multispecies bioassays and chronic toxicity data by converting acute data with the acute-to-chronic ratios (ACRs); the derived WQC were then used to evaluate the ecological risk for TCEP in China Seas. According to median effective concentration (EC50) and median lethal concentration (LC50), TCEP had a moderate or low toxicity to eight marine species selected, among which mysid Neomysis awatschensis (96h-LC50 of 39.65 mg/L) and green alga Platymonas subcordiformis (96-h EC50 of 395.42 mg/L) were the most sensitive and the most tolerant, respectively. The acute and chronic hazardous concentrations of TCEP for 5% of marine species (HC5) were estimated to be 29.55 and 2.68 mg/L, respectively. The short-term and long-term WQC were derived to be 9.85 and 0.89 mg/L, respectively. The risk quotient (RQ) values indicated that TECP at current levels poses a negligible risk to marine ecosystems in China. These results will provide valuable reference for the government to establish a seawater quality standard for TCEP.

Ecological risk assessment for xylenes and propylbenzenes in aquatic environment using a species sensitivity distribution approach

Xylenes and propylbenzenes (PBZs) are volatile aromatic hydrocarbons with high aquatic toxicity. Xylenes can be present in three isomers: o-xylene (OX), m-xylene (MX), and p-xylene (PX), while PBZs include two isomers: n-propylbenzene (n-PBZ) and isopropylbenzene (i-PBZ). Their accidental spills and improper discharges from petrochemical industries can cause severe contamination in water bodies posing potential ecological risks. In this study, the published acute toxicity data of these chemicals for aquatic species were collected to calculate hazardous concentrations protecting 95% species (HC₅) using a species sensitivity distribution (SSD) approach. The acute HC₅ values for OX, MX, PX, n-PBZ, and i-PBZ were estimated to be 1.73, 3.05, 1.23, 1.22, and 1.46 mg/L, respectively. The risk quotient (RQ) values calculated based on HC₅ indicated their high risk (RQ: 1.23 ∼ 21.89) in groundwater, but low risk (RQ < 0.1) in natural seawater, river water, and lake water. When xylenes or PBZs leaked into the sea, they were expected to pose a high risk (RQ > 1) at the start and then a low risk (RQ < 0.1) after 10 days due to natural attenuation. These results may help to derive more reliable protection thresholds for xylenes and PBZs in aquatic environment and provide a basis for evaluating their ecological risks.

Occurrence and ecological risk assessment of 16 phthalates in surface water of the mainstream of the Yangtze River, China

Phthalic acid esters (PAEs), a class of typical endocrine disruptors, have received considerable attention due to their widespread applications and adverse effects on biological health. In this study, 30 water samples, along the mainstream of the Yangtze River (YR), were collected from Chongqing (upper stream) to Shanghai (estuary) from May to June in 2019. The total concentrations of 16 targeted PAEs ranged from 0.437 to 20.5 μg/L, with an average of 1.93 μg/L, where dibutyl phthalate (DBP, 0.222-20.2 μg/L), bis (2-ethylhexyl) phthalate (DEHP, 0.254-7.03 μg/L), and diisobutyl phthalate (DIBP, 0.0645-0.621 μg/L) were the most abundant PAEs. According to the pollution level in the YR to assess the ecological risk posed by PAEs, the results showed medium risk level of PAEs in the YR, among which DBP and DEHP posed a high ecological risk to aquatic organisms. The optimal solution for DBP and DEHP is found in ten fitting curves. The PNEC_SSD of them is 2.50 μg/L and 0.34 μg/L, respectively.

Acute toxicity and risk assessment of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS) in tropical cladocerans Moina micrura

Per- and polyfluoroalkyl substances (PFAS) are gaining worldwide attention because of their toxicity, bioaccumulative and resistance to biological degradation in the environment. PFAS can be categorised into endocrine disrupting chemicals (EDCs) and identified as possible carcinogenic agents for the aquatic ecosystem and humans. Despite this, only a few studies have been conducted on the aquatic toxicity of PFAS, particularly in invertebrate species such as zooplankton. This study evaluated the acute toxicity of two main PFAS, perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS), by using freshwater cladocerans (Moina micrura) as bioindicators. This study aimed to assess the adverse effects at different levels of organisations such as organ (heart size and heart rate), individual (individual size and mortality) and population (lethal concentration, LC₅₀). PFOA was shown to be more hazardous than PFOS, with the LC₅₀ values (confidence interval) of 474.7 (350.4-644.5) μg L^-1 and 549.6 (407.2-743.9) μg L^-1, respectively. As the concentrations of PFOS and PFOA increased, there were declines in individual size and heart rate as compared to the control group. The values of PNECs acquired by using the AF method (PNEC_AF) for PFOA and PFOS were 0.4747 and 0.5496 μg L^-1, respectively. Meanwhile, the PNEC values obtained using the SSD method (PNEC_SSD) were 1077.0 μg L^-1 (PFOA) and 172.5 μg L^-1 (PFOS). PNEC_AF is more protective and conservative compared to PNEC_SSD. The findings of this study have significant implications for PFOS and PFOA risk assessment in aquatic environments. Thus, it will aid freshwater sustainability and safeguard the human dependency on water resources.

Water quality criteria derivation and tiered ecological risk evaluation of antifouling biocides in marine environment

This study provides a comprehensive compilation of published toxicological and environmental data further used to assess the ecological risks of six antifouling biocides, including tributyltin (TBT), Irgarol 1051, Diuron, Chlorothalonil, 4,5-Dichloro-N-octyl-3(2H)-isothiazolone (DCOIT), and Dichlofluanid. The standard maximum concentration and standard continuous concentration of antifouling biocides were derived by the species susceptibility distribution method. Following that, the ecological risk assessment of antifouling biocides in the aquatic environment was conducted using the hazard quotient, margin of safety, joint probability curve, and Monte Carlo random sampling method. The following is a concise list of the antifouling biocide dangers associated with acute and chronic risks: Irgarol 1051 > TBT > Diuron > DCOIT > Chlorothalonil > Dichlofluanid. It is strongly advised that systematic and ongoing monitoring of these biocides in coastal areas take place, as well as the creation of acceptable and efficient environmental protection measures, to safeguard the coastal environment's services and functions.

Occurrence and ecological risk assessment of 2,2',4,4'-tetrabromodiphenyl ether and decabromodiphenyl ether in surface waters across China

Polybrominated diphenyl ethers (PBDEs) are efficient brominated flame retardants and are released into various environmental media via usage, recycling and disposal. This study investigated the concentrations and ecological risks of two typical PBDEs, 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) and decabromodiphenyl ether (BDE-209), in surface waters across China from 2011 to 2018. The results showed that the concentration of BDE-209 (8.25 ng L^-1) was higher than that of BDE-47 (1.02 ng L^-1), and the concentrations of BDE-47 and BDE-209 in the lakes (2.56 ng L^-1 and 22.19 ng L^-1, respectively) were higher than those in the rivers (0.58 ng L^-1 and 7.05 ng L^-1, respectively). In addition, the concentration of BDE-209 in the wet season (2.61 ng L^-1) was lower than that in the dry season (10.83 ng L^-1), whereas the concentration of BDE-47 in the wet season (0.24 ng L^-1) was a little lower than that in the dry season (0.99 ng L^-1). BDE-47 and BDE-209 concentrations showed a gradual decrease in surface waters across China during the eight-year period. Based on the species sensitivity distribution (SSD) models, the 5% hazardous concentration (HC₅) and predicted no-effect concentration (PNEC) values were derived using the acute and chronic toxicity data of BDE-47 and BDE-209. Results showed that the PNEC values based on the acute and chronic toxicity data were 2.08 μg L^-1 and 0.52 μg L^-1 for BDE-47, respectively and 370 μg L^-1 and 0.34 μg L^-1 for BDE-209, respectively. The risk quotient (RQ) values of BDE-47 in surface waters across China were far smaller than 0.1 (low ecological risk). Similarly, the RQ values of BDE-209 were also smaller than 0.1, except for those at Baiyangdian Lake and Chaohu Lake, where the probability of 0.1 ≤ RQ < 1.0 (medium ecological risk) was approximately 10% based on 10,000 Monte Carlo simulations.

A novel procedure for predicting chronic toxicities and ecological risks of perfluorinated compounds in aquatic environment

Perfluorinated compounds (PFCs) can pose adverse effect on aquatic species and community structure. However, little is known about how the characteristics of molecules of PFCs affect their chronic toxic potencies to aquatic species, and the species sensitivity distributions (SSDs) and ecological risk assessments of PFCs are hampered by limited available data of chronic toxicity. In the present study, a novel procedure is proposed to obtain the ecological risk of PFCs using existing exposure concentrations of PFCs and SSDs integrated with the chronic toxicity prediction through robust QSAR models. The results showed that the energy of the lowest unoccupied molecular orbital (E_LUMO) exhibited the strongest correlation with the chronic toxicities of 15 PFCs (R² > 0.844, F > 16.206, p < 0.05). SSDs of 15 PFCs on eight species were first constructed, and the SSD fitting parameters were significantly correlated with E_LUMO (R² > 0.610, F > 19.471, p < 0.05). The QSAR-SSDs support the evaluation of hazardous criteria of PFCs for which data are lacking. Given environmental exposure distributions (EEDs) of the national presence of PFCs in aquatic systems in China, the QSAR-SSDs models allow the development of the ecological risk assessment for PFCs. This way, it was concluded that negligible environmental risk (defined as 5% of the species being potentially exposed to concentrations able to cause effects in < 5% of the case) could be expected from exposure to PFCs in surface waters in China. This method may be helpful for providing an evidence-based approach to guide the risk management for PFCs in aquatic environment.

Development of ecological risk assessment for Diisobutyl phthalate and di-n-octyl phthalate in surface water of China based on species sensitivity distribution model

Phthalic acid esters (PAEs) are commonly used as plasticizer and are emerging concern worldwide for potent adverse effects of aquatic organisms. Certain PAEs were often detected in different environmental matrices but related toxicity data were still lacking to support their risk assessment. The study investigated the acute toxicity of Diisobutyl phthalate (DiBP) and Di-n-octyl phthalate (DnOP) using 6 Chinese resident aquatic organisms from 3 phyla and 6 species and constructed the species sensitivity distribution (SSD) models for ecological risk assessment. Lethal concentration 50% (LC₅₀) ranges of DiBP and DnOP were 4.89-21.45 mg/L and 1.45-1200 mg/L, respectively. The derived acute and chronic predicted no-effect concentrations (PNECs) based on log-normal model of water were 0.54 and 0.04 mg/L for DiBP and 0.23 and 0.05 mg/L for DnOP, respectively. The ERA for DiBP and DnOP in the surface water and sediment of China was conducted. Water samples of Haihe Rive (RQ = 0.41) and Hun River (RQ = 0.16) of DiBP showed medium risk. And sediment samples of Yellow River (RQ = 0.71) and Chao Hu Lake (RQ = 0.42) of DiBP showed medium risk. Meanwhile, the above water and sediment samples (RQ＜0.1) of DnOP showed low risk.

Separate and combined effects of cadmium (Cd) and nonylphenol (NP) on growth and antioxidative enzymes in Hydrocharis dubia (Bl.) Backer

Cadmium (Cd) is considered a priority pollutant, and nonylphenol (NP) is a common organic pollutant in water environments. However, the ecological risks of combined Cd and NP pollution have not been fully elucidated. In this study, the effects of Cd, NP, and Cd-NP on the growth and physiology of Hydrocharis dubia (Bl.) Backer were studied. The results indicated that Cd-NP joint toxicity is concentration-dependent. The joint toxicity of Cd and NP on H. dubia was antagonistic when the concentrations of Cd + NP were 0.01 + 0.1/1 mg/L. At 0.5 + 0.1/1 mg/L, Cd and NP had a strong synergistic effect on H. dubia. In addition, plant growth was significantly inhibited, and the chlorophyll contents were significantly reduced under Cd, NP, or Cd-NP exposure. The plant's antioxidant enzyme system was destroyed. The activities of superoxide dismutase (SOD) and catalase (CAT) were significantly decreased under NP-only exposure. The activity of SOD was significantly decreased under Cd-only and under joint exposure. Compound pollution exceeded the oxidative defense capacity of the plants, so the H₂O₂ content increased significantly. Our results indicated that the ecotoxicity of NP combined with Cd may be exacerbated in aquatic environments and cause obvious damage to H. dubia.

A tiered probabilistic approach to assess antibiotic ecological and resistance development risks in the fresh surface waters of China

Exposure to antibiotics can result in not only ecotoxicity on aquatic organisms but also the development of antibiotic resistance. In the study, the ecotoxicity data and minimum inhibitory concentrations of the antibiotics were screened to derive predicted no-effect concentrations of ecological (PNEC_eco) and resistance development risks (PNEC_res) for 36 antibiotics in fresh surface waters of China. The derived PNEC_eco and PNEC_res values were ranged from 0.00175 to 2351 μg/L and 0.037-50 μg/L, respectively. Antibiotic ecological and resistance development risks were geographically widespread, especially in the Yongding River, Daqing River, and Ziya River basins of China. Based on the risk quotients, 11 and 14 of 36 target antibiotics were at high ecological risks and high resistance development risks in at least one basin, respectively. The higher tiered assessments provided more detailed risk descriptions by probability values and β-lactams (penicillin and amoxicillin) were present at the highest levels for ecological and resistance development risks. Although there was uncertainty based on the limited data and existing methods, this study can indicate the overall situation of the existing risk levels and provide essential insights and data supporting antibiotic management.

Distribution, source and ecological risk of per- and polyfluoroalkyl substances in Chinese municipal wastewater treatment plants

Municipal wastewater treatment plants (WWTPs) are sinks of per- and polyfluoroalkyl substances (PFASs) generated by human activities and are also sources of PFASs in aquatic environment. This study analyzed distribution, source and ecological risk of 14 PFASs in influent and effluent samples from 148 Chinese municipal WWTPs. Composition and concentrations of PFASs in the influents and effluents had obvious spatial differences. Fluoropolymer processing aids/wrappers and textile treatments/coatings were found to be the dominant sources in WWTP influents, which accounted for 78.34% of all sources. Consumption structure and metal and transportation equipment manufacturing affected the spatial differences of PFASs in WWTPs. Further, mean removal rate of total PFASs in all WWTPs was -5.45%. The conventional treatment processes can not effectively remove PFASs and no significant difference was found among different treatment processes. However, risk quotient values of PFASs in effluents were all below 0.1, indicating low risk or no risk to aquatic organisms. It should be noted that the composition, source and ecological risk of PFASs in east China were different from the other regions, which need more attentions. This study sheds insights into occurrencesof PFASs in municipal WWTPs, which should be helpful for their control strategy development.

Modelling of micropollutant fate in hybrid growth systems: model concepts, Peterson matrix, and application to a lab-scale pilot plant

Modelling the fate of micropollutants in different wastewater treatment processes is of present concern. Moreover, during the last few years, there has been an increasing interest in the development of hybrid reactors which contain both suspended biomass and biofilm. Here, a new model developed which tries to determine the fate of micropollutants in hybrid reactors such as moving bed biofilm reactor (MBBR) and called the ASM-biofilm-MPs model considered the main mechanisms leading to the micropollutant removal (sorption/desorption, biodegradation, cometabolism) in hybrid reactors. This dynamic model describes the fate of micropollutants in a hybrid reactor using first-order kinetics for biotransformation and sorption/desorption equations. Also, it considered the reactions for carbon oxidation, nitrification, and denitrification in attached and suspended biomass under aerobic conditions. The mathematical model consists of three connected models for the simulation of micropollutants, suspended biomass, and biofilm. Biochemical conversions are evaluated according to the Activated Sludge Model No. 1 (ASM1) for both attached and suspended biomass. The model is applied for a laboratory MBBR, which fed with synthetic wastewater containing 4-nonylphenol (4-NP) as micropollutant, and accurately describes the experimental concentrations of COD, attached and suspended biomass, nitrogen, and 4-NP micropollutant obtained during 180 days working at different loadings. The differences between simulations and experiments in all operational periods for sCOD, NH₄-N, NO₃-N, and attached and suspended biomass concentrations were less than 15%, 10%, 10%, 5% and 5%, respectively. Finally, the contribution of adsorption and biodegradation mechanisms in the fate of 4-NP was calculated, when 4-NP concentration is set to 1 µg/L (biodegradation = 86.5%, sorption = 5%) and 50 µg/L (biodegradation = 55.9%, sorption = 34.7%).

Probabilistic risk assessment of heavy metals in urban farmland soils of a typical oasis city in northwest China

Previous studies lacked quantitative evaluation studies of the probability of ecology and human health risks from soil heavy metals. This study assessed heavy metal risk level by collecting topsoil samples from a typical oasis city (Wuwei) in northwest China and then quantitatively evaluating the ecological risk from heavy metals by incorporating the uncertainty of health risk model parameters into the risk assessment. This study found that anthropogenic activities have influenced the accumulation of heavy metals in the study area and that the risk of contamination of soil heavy metals was characterized as light to moderate contamination and low ecological risk. On this basis, the species sensitivity distribution curves of heavy metals were constructed using species acute toxicity data, the predicted no effect concentrations of heavy metals were derived, and a probabilistic ecological risk evaluation was conducted. The results show that the current soil environmental quality standards in China are not effective in protecting species diversity. In addition, the probability of ecological risk for Cr, Ni and As in the study area was 63.3%, 23.8% and 7.1%, however, traditional pollution assessment methods underestimate the hazard of Cr. Monte Carlo simulations have shown that the probability of the carcinogenic risk of Cr (adults: 79.4%; children: 94.5%) and As (adults: 78.9%; children: 94.0%) is high, the probability of the total carcinogenic risk exceeding 1E-06 is 99.0%, the probability of the non-carcinogenic risk is low, and the slope factor and reference dose can significantly affect the evaluation of human health risks.

Cyanotoxins and water quality parameters as risk assessment indicators for aquatic life in reservoirs

We assessed the extent of pollution in an essential public water supply reservoir (southeastern Brazil). An environmental monitoring study was performed at the Billings Reservoir (at the water catchment site) to assess the water quality in 2017, 2018, and 2019. Physicochemical parameters were analyzed, quantifying the total cyanobacteria and the cyanotoxins microcystins (MCs) and saxitoxins (SXTs), as well as their possible ecological risk to the aquatic environment. We also determined metals and metalloids (As, Ba, Cd, Pb, Cu, Cr, Fe, Mn, Ni, Zn, and Sb) and fecal bacteria (Escherichia coli). Monthly samplings were performed for 2017, 2018, and 2019 (totaling 36 sampling campaigns). Metals, metalloids, and E. coli values were below the maximum limit allowed by the Brazilian legislation. High concentrations of total cyanobacteria (3.07 × 10⁴ - 3.23 × 10⁵ cells/mL), microcystin variants MC-LR (0.67-23.63 μg/L), MC-LA (0.03-8.66 μg/L), MC-RR (0.56-7.92 μg/L), and MC-YR (0.04-1.24 μg/L), as well as the saxitoxins GTX2 (0.18-5.37 μg/L), GTX3 (0.13-4.40 μg/L), and STX (0.12-2.92 μg/L) were detected. From an ecotoxicological point of view, the estimated values for the risk quotient (RQ) for microcystins and saxitoxins were largely greater than 1, indicating a high risk to aquatic life. Therefore, further efforts need to be made to delay the eutrophication of the reservoir.

Deriving the predicted no effect concentrations of 35 pesticides by the QSAR-SSD method

The widespread use of pesticides results in their frequent detection in water bodies and other environmental media. Pesticide residues may cause certain risks to the environment and human health, and reliable predicted no effect concentrations (PNEC) must be obtained when assessing environmental risks. Species sensitivity distribution (SSD) is an important method for the derivation of chemical PNECs. Construction of the SSD model requires sufficient toxicity data to various species including at least eight families in three phyla, suitable nonlinear fitting functions and assessment factors (AFs) with certain uncertainty. However, most chemicals could not collect sufficient species toxicity data, while some chemicals had sufficient species toxicity data but could not find suitable fitting functions, thus hindering the construction of effective SSD models. To this end, the established QSAR models were applied to predict toxicity of chemicals to specific species to fill in the toxicity data gaps required for SSD and selecting multiple nonlinear functions to optimize the SSD model. Combined with QSAR and SSD methods, a new method of PNEC derivation was developed and successfully applied to the derivation of PNEC for 35 pesticides. Three QSAR models were used to predict the toxicities of six pesticides with few toxicity data. Nine two-parameter nonlinear functions were used to fit the toxicity-cumulative probability data one by one to determine the optimal SSD models. The hazardous concentrations at the cumulative probability of 5% and 10%, i. e, HC₅ and HC₁₀, respectively, were calculated by the optimal SSD model. The assessment factor used to determine the PNEC of the chemical based on the HC₁₀ was derived from the quantitative correlation between HC₁₀ and HC₅ of pesticides found in this study. When the toxicity data are insufficient, it may be more appropriate to calculate the PNECs of chemicals using HC₁₀ than using HC₅.

Hardness-Dependent Water Quality Criteria for Protection of Freshwater Aquatic Organisms for Silver in China

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 R² 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.

Tiered ecological risk assessment of nonylphenol and tetrabromobisphenol A in the surface waters of China based on the augmented species sensitivity distribution models

The ecological risks of nonylphenol (NP) and tetrabromobisphenol A (TBBPA) have received continued attention owing to their large consumption, frequently detection, adverse effects on the reproductive fitness, and lack of risk assessment technical systems. The geometric mean of the median concentrations of NP in the 22 surface waters was 0.278 μg/L, and TBBPA in the seven surface waters was 0.014 μg/L in China. The species sensitivity distribution (SSD) models were augmented by extrapolated reproductive toxicity data of native species to reduce uncertainty. The SSD models and the hazardous concentrations for 5% of species exhibited good robustness and reliability using the bootstrap method and minimum sample size determination. The acute and reproductive predicted no-effect concentrations (PNECs) were derived as 9.88 and 0.187 μg/L for NP, and 56.6 and 0.0878 μg/L for TBBPA, respectively. The risk quotients indicated that 11 of 22 locations for NP, and 3 of 7 locations for TBBPA were at high ecological risk levels based on the reproductive PNECs. Furthermore, the higher tier ecological risk assessment (ERA) based on potential affected fraction and joint probability curves indicated that the ecological risks in the four of above locations needed further concern. The ERA based on both the acute and reproductive toxicity is essential for assessing the ecological risks of NP and TBBPA, otherwise using acute PNECs only may result in an underestimation of ecological risk. The developed tiered ERA method and its framework can provide accurate, detailed, quantitative, locally applicable, and economically technical support for ERA of typical endocrine-disrupting chemicals in China.

Estrogenic activity and ecological risk of steroids, bisphenol A and phthalates after secondary and tertiary sewage treatment processes

Effluents of sewage treatment plants (STPs) are an important source of estrogenic substances to the receiving water bodies affecting their ecological safety. In this study, steroids, bisphenol A (BPA) and phthalates were assessed in the secondary (SE) and tertiary effluent (TE) of three typical urban STPs in Beijing (China). In addition, the overall estrogenic activity in these effluents was assessed by an in-vitro bioassay (ERE-CALUX). Results showed that the concentrations and activities of estrogenic compounds in TE were lower than those in SE. The residual concentration of 17β-estradiol (E2) was the highest among the detected steroids, accounting for 51.6 ± 5.1% in SE and 57.5 ± 24.8% in TE. The residual level (25.2-41.6 ng/L) of BPA in effluents was significantly higher than that of steroids (0.2-28.8 ng/L). The residual concentration of diethyl phthalate was the highest among the detected phthalates accounting for 47.1 ± 5.1% in SE and 37.6 ± 11.5% in TE. Steroids and BPA had a higher removal rate (83.5% and 96.7%) in secondary and tertiary treatment than phthalates (68.8% and 83.1%). The hydrophobic characteristics of these estrogenic compounds determined the removal mechanism. The removal of steroids, BPA, dimethyl phthalate and diethyl phthalate (LogKow= 1.61-4.15) mainly occurred through biodegradation in the water phase, while the removal of dibutyl phthalate, butylbenzyl phthalate and di(2-ethylhexyl) phthalate (LogKow= 4.27-7.50) mainly occurred in the solid phase after adsorption on and sedimentation of the suspended particulate matter. According to ERE-CALUX, the estrogenic activity in the final STP effluents was 3.2-45.6 ng E2-equivalents/L, which is higher than reported levels in the effluents of European STPs. Calculation of estrogenic equivalents by using substance specific chemical analysis indicated that the dominant contributor was E2 (56.4-88.4%), followed by 17α-ethinylestradiol (EE2) (4.1-34.8%), both also exerting a moderate risk to the aquatic ecosystem. While the upgrade of treatment processes in STPs has efficiently reduced the emission of estrogenic substances, their ecological risk was not yet phased out.

Chronic effects of clothianidin to non-target soil invertebrates: Ecological risk assessment using the species sensitivity distribution (SSD) approach

This study aimed to assess the chronic toxicity and risk of clothianidin in a seed dressing formulation to non-target soil invertebrates. The toxicity assays were performed with two oligochaetes (earthworms Eisenia andrei and enchytraeids Enchytraeus crypticus) and three collembolans (Folsomia candida, Proisotoma minuta and Sinella curviseta) species following ISO protocols. Risk assessment (via Hazard Quotient approach - HQ) was based on the hazardous concentrations for 95% of the species (HC₅), derived from chronic Species Sensitivity Distributions (SSD) for clothianidin, and on its predicted environmental concentrations (PEC). Four SSD scenarios were generated with literature and/or this study data, following different data selection criteria (i.e., general, only data from tests using similar formulations, similar soils, or identical soil/formulation). In our experiments, a higher clothianidin toxicity (EC₅₀-based) was found for collembolans (varying from 0.11 to 0.28 mg kg^-1 between species) followed by the earthworms (4.35 mg kg^-1), while the enchytraeids were the least sensitive (33.5 mg kg^-1). HQ indicated a significant risk of clothianidin to soil invertebrates because the estimated PEC were at least 16.6 times higher than HC₅ and are expected to affect the whole group of collembolans. Despite the criteria for data inclusion have influenced the HC₅ values, no substantial changes were observed for the risk outcomes. To our knowledge, this is the first study assessing the chronic ecological risk of clothianidin to beneficial soil fauna based on a probabilistic SSD approach. Data from this study can help to derive more reliable protection thresholds for clothianidin in soils.

Perfluorooctanoic Acid (PFOA) and Perfluorooctanesulfonic Acid (PFOS) in Surface Water of China: National Exposure Distributions and Probabilistic Risk Assessment

This study presents a comprehensive application of the probabilistic risk assessment methodology for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), which are two types of perfluoroalkyl acids frequently studied in recent years. The exposure characteristics of PFOA and PFOS in Chinese surface water on a nationwide scale were summarized. Individual predicted no-effect concentration (PNEC) and the sensitivities for taxonomic groups of primary producers, invertebrates, and vertebrates were derived by the species sensitivity distributions method. Both hazard quotients (HQs) and joint probability curves were calculated to assess the risks to aquatic organisms. Among seven Chinese river basins, the mean concentrations of PFOA and PFOS in the Yangtze River Basin were the highest (58 ng/L and 22 ng/L, respectively), while the lowest concentrations (< 1 ng/L) were in the Songhua River Basin. The acute PNEC value was 2.43 mg/L for PFOA and 0.96 mg/L for PFOS, and the chronic PNEC value was 0.0067 mg/L for PFOA and 0.0012 mg/L for PFOS, respectively. The sensitivities of different taxonomic groups revealed higher sensitivity of primary producers for PFOA and higher sensitivity of invertebrates for PFOS. The acute HQs of PFOA and PFOS were less than 1. The probabilities of exposure concentrations exceeding 5th percentile toxicity value of the chronic data for all aquatic organisms were 1.65% for PFOA and 1.23% for PFOS, respectively, suggesting a low probability of effects to aquatic organisms. Compared with the risk scenarios worldwide, the ecological risks for chronic effects decreased in the order of PFOS (worldwide) > PFOA (China) > PFOS (China) > PFOA (worldwide).

Development of regional water quality criteria of lead for protecting aquatic organism in Taihu Lake, China

Lead is a widely distributed priority controlled heavy metals in aquatic system, its toxicity to aquatic organisms affected by water quality parameters. This study investigated the acute toxicity of lead (Pb) to the aquatic organisms in Taihu Lake under various water hardness, corresponding regional water quality criteria were derived. The acute toxicity experimental results revealed that the toxicity of Pb to aquatic organisms increased with water hardness. The Pb toxicity has a highest toxicity at water hardness 50 mg/L (expressed as CaCO₃), especially for Palaemon modestus where the 96 h LC₅₀ value was 0.024 mg/L. The hazardous concentration for 5% of biological species (HC₅) values were determined via species sensitivity distribution (SSD) method as 94.0 μg/L, 222.3 μg/L and 375.8 μg/L for Pb at water hardness 50, 150, and 250 mg/L, respectively. The assessment factor (AF) value was set at 2, followed by the current SSD framework where European commission recommend a fixed AF of 5-1. Thus, the predicted no effect concentration (PNEC) values was 47.0 μg/L, 111.2 μg/Land 187.9 μg/L at water hardness 50, 150, and 250 mg/L, respectively. Meanwhile, the short-term water quality criteria of Pb for Taihu lake aquatic organisms were derived as 111.2 μg/L at water hardness 150 mg CaCO₃/L. The long-term water quality criteria were derived as 4.3 μg/L by using acute/chronic ratio 51.29. When the derived value was used for Taihu Lake, 2.7% of the sampling sites in Taihu Lake was exceeded this criterion. The results of this study can provide technical methods and basic information for deriving Pb regional water quality criteria for protecting native aquatic organisms, in China.

Benzophenones and synthetic progestin in wastewater and sediment from farms, WWTPs and receiving surface water: distribution, sources, and ecological risks

Farms and wastewater treatment plants (WWTPs) are important sources of endocrine disruptors, which may have potential adverse effects on the nearby receiving river and potential human health risks. Benzophenone (BPs) and synthetic progestin were determined in water and sediment samples of the discharge source and receiving river. BPs and synthetic progestin ranged from not detected (N.D.) to 400.53 ng L⁻¹ in water samples and from N.D. to 359.92 ng g⁻¹ dw in sediment, respectively, and benzophenone-3 (BP-3) and ethinyl estradiol (EE2) were the main detected objects. Correlation analysis showed that pollutants discharged from livestock farms were the main contributor to the receiving river. The distribution of pollutants in different regions was related to higher population density and livestock activities. Predicted no-effect concentrations (PNECs) were investigated for ecological risk assessment in the study area, and 86% of the samples exceeded the baseline value of chronic toxicity. Benzophenone-1 (BP-1), benzophenone-3 (BP-3), 4-hydroxybenzophenone (4-OH-BP) and benzophenone (BP) were identified as the main substances that caused medium risk in the aquatic ecosystem. Therefore, BPs and synthetic progesterone should be given more attention in the future.

The occurrence, source and ecological risk of BPs and synthetic progestin in farms, WWTPs and their receiving river were investigated.

Cumulative impact assessment of hazardous ionic liquids towards aquatic species using risk assessment methods

In the present research work, a comprehensive tool for cumulative ecotoxicological impact assessment of ionic liquids (ILs) to aquatic life has been constructed. Using the probabilistic tool, impact of individual ILs to a group of aquatic species is assessed by chemical toxicity distributions (CTDs). The impact of group of ILs to individual aquatic species is assessed by species sensitivity distributions (SSDs). Acute toxicity data of imidazolium ILs with chloride (Cl^-), bromide (Br^-), tetrafluoroborate (BF4^-), and hexafluorophosphate (PF6^-) anions are used in CTD and SSD. Allowable concentrations for a group of Imidazolium ILs with the same mode of action (SMOA) to five aquatic species; Daphnia magna, Vibrio fischeri, Algae, Zebrafish, and Escherichia coli are estimated by CTDs. It has been concluded that 1-Butyl-3-methylimidazolium chloride (BMIMCl) possess the lowest risk at an acceptable risk value of 750 × 10^-5 mmol/L which is 12% less than that of OMIMCl. Furthermore, the sensitivities towards the aquatic species reveal that from the studied ILs, BMIMBF4 with an acceptable risk value of 3200 × 10^-5 mmol/L is the most suitable IL towards the selected aquatic species. Hence, current work provides cumulative allowable concentrations and acceptable risk values for ILs which release to aquatic compartment of ecosystem.

Ecological and human health risk assessment of total petroleum hydrocarbons in surface water and sediment from Woji Creek in the Niger Delta Estuary of Rivers State, Nigeria

This study was designed to assess total petroleum hydrocarbon (THP) concentrations in the surface water and sediment sampled from Woji Creek and to assess potential ecological and human health risk due to petroleum hydrocarbons along the creek. Physicochemical parameters [pH, temperature (T), electrical conductivity (EC), dissolved oxygen (DO), total dissolved solids (TDS)] were in-situ measured from sediment and surface water; hydrological parameters (width, depth and volume) were used to calculate the flow rate (discharge) at different stations of the creek. Trend of TPH in the surface water samples along the creek were as follows: St4 (3.639 ± 1.121 mg/L) > St3 (2.449 ± 0.623 mg/L) > St1 (1.457 ± 0.244 mg/L) > St2 (1.069 ± 0.228 mg/L) > St5 (1.010 ± 0.120 mg/L) Trend of TPH concentration across the creek was as follows: St1 - 8.758 ± 0.697 mg/kg > St3 - 7.675 ± 0.541 mg/kg > St5 - 5.515 ± 0.401 mg/kg > St4 - 5.075 ± 0.363 mg/kg > St2 - 3.162 ± 0.307 mg/kg. Diagnostic indices indicate that the hydrocarbon in the creek was from petrogenic source. Estimation of ecological risk indicated risk in the surface water but not in the sediment. However, human health risk assessment indicated no risk due to human ingestion of the sediment or surface water.

Concentrations, distribution, and risk assessment of heavy metals in the iron tailings of Yeshan National Mine Park in Nanjing, China

For the first time, a field survey was conducted to investigate the present situation, vertical distribution and ecological risks of heavy metals (Cu, Zn, Mn, Cr, Pb and As) from 21 in-situ samples drilled out from Yeshan iron mine tailings in the Jiangsu Province of China. The heavy metal contents obtained for the tailing wastes in decreasing order were as follows: Mn > Cu > Zn > As > Cr > Pb. The contents of heavy metals varied with depth, and the variation trends were not completely consistent. Vertical distribution profiles showed that heavy metals accumulated in certain strata. Both the monomial potential ecological risk factor (E) and the risk quotient (RQ) showed a high ecological risk for Cu, Mn and As. The comprehensive ecological risk index (RI) also indicated that the wastes presented a high ecological risk level, to which Cu, Mn and As were the key contributors. Our study showed that the health of individuals, especially children, living in the mining-impacted areas could be affected by the potential noncarcinogenic risk of copper, manganese and the carcinogenic risk of arsenic.

Selected Pharmaceuticals in Different Aquatic Compartments: Part II-Toxicity and Environmental Risk Assessment

Potential risks associated with releases of human pharmaceuticals into the environment have become an increasingly important issue in environmental health. This concern has been driven by the widespread detection of pharmaceuticals in all aquatic compartments. Therefore, 22 pharmaceuticals, 6 metabolites and transformation products, belonging to 7 therapeutic groups, were selected to perform a review on their toxicity and environmental risk assessment (ERA) in different aquatic compartments, important issues to tackle the water framework directive (WFD). The toxicity data collected reported, with the exception of anxiolytics, at least one toxicity value for concentrations below 1 µg L⁻¹. The results obtained for the ERA revealed risk quotients (RQs) higher than 1 in all the aquatic bodies and for the three trophic levels, algae, invertebrates and fish, posing ecotoxicological pressure in all of these compartments. The therapeutic groups with higher RQs were hormones, antiepileptics, anti-inflammatories and antibiotics. Unsurprisingly, RQs values were highest in wastewaters, however, less contaminated water bodies such as groundwaters still presented maximum values up to 91,150 regarding 17α-ethinylestradiol in fish. Overall, these results present an important input for setting prioritizing measures and sustainable strategies, minimizing their impact in the aquatic environment.

Ecological risk assessment of petroleum hydrocarbons on aquatic organisms based on multisource data

From the perspective of ecological risk, this study uses a multisource data method to search for global data, uses the acute and chronic ratio method to process the data, uses the species-sensitive distribution method to evaluate the ecological risk that petroleum hydrocarbons pose to aquatic organisms, and evaluates the ecological risk of the water environment in five Chinese water bodies. The results are as follows. First, in an aquatic ecosystem, the toxicological effects of petroleum hydrocarbons were found to be more obvious on consumers, and the sensitivity of fish was found to be higher than that of crustaceans. Second, the acutely lethal effects of petroleum hydrocarbons, fluorene, and benzo [a] pyrene on aquatic ecosystems were fitted by using the documentary method of multisource data collection and a Log-logistic curve. Third, in the case study evaluation of five Chinese water bodies, the ecological risks of polycyclic aromatic hydrocarbons were ranked (from low to high) as fluorene < benzo [a] pyrene. The ecological risk values of benzo [a] pyrene were all greater than 1. These risks should not be underestimated, and prevention and control work should be performed.

Emergent contaminants in sediments and fishes from the Tamsui River (Taiwan): Their spatial-temporal distribution and risk to aquatic ecosystems and human health

The occurrence of emergent contaminants, 24 polybrominated diphenyl ethers (PBDEs), di(2-ethylhexyl)phthalate (DEHP), dibutyl phthalate (DBP), butyl benzyl phthalate (BBP), diethyl phthalate (DEP), dimethyl phthalate (DMP), di-n-octyl phthalate (DnOP), bisphenol A (BPA) and nonylphenol (NP), was investigated in sediments and fishes collected from the Tamsui River system to determine the factors that influence their distribution and their risk to aquatic ecosystems and human health. The concentrations of total PBDEs, DEHP, DBP, BBP, DEP, DMP, DnOP, BPA and NP in sediments were 1-955, ND-23570, <50-411, <50-430, ND-80, ND-<50, ND-<50, 1-144, 3-19624 μg/kg dw, respectively. The spatial-temporal distribution trends of these compounds in sediments could be attributed to urbanization, industrial discharge and effluents from wastewater treatment plants. The PBDE congener distribution patterns (BDE-209 was the dominant congener) in sediments reflected the occurrence of debromination of BDE-209 and the elution of penta-BDE from the treated products. The concentrations of total PBDEs, DEHP, DBP, BBP, DEP, DMP, DnOP, BPA and NP in fish muscles were 2-66, 17-1046, <10-231, <10-66, <30, ND-<30, ND-<30, 0.4-7 and 3-440 μg/kg ww, respectively. The species-specific bioaccumulation of these compounds by fish was found and four species particularly showed high bioaccumulation potential. BDE-47 was the predominant BDE congener in fish muscles, suggesting high bioavailability and bioaccumulation of this compound. The results of biota-sediment accumulation factors showed that BDE-47, 99, 100, 153 and 154 had relatively high bioavailability and bioaccumulation potential for some fish species. The ecological risk assessment showed that the concentrations of BPA and NP in sediments were likely to have adverse effects on aquatic organisms (risk quotients > 1). The human health risk assessment according to hazard quotients (HQs) and carcinogenic risks (CRs) revealed no remarkable risk to human health through consumption of fish contaminated with BDE-47, 99, 100, 154, 209, DEHP, BPA and NP.

Quinolones antibiotics in the Baiyangdian Lake, China: Occurrence, distribution, predicted no-effect concentrations (PNECs) and ecological risks by three methods

The occurrence, distribution, and ecological risk of 10 quinolones (QNs) were investigated in the water and sediment samples from Baiyangdian Lake, China. The field samplings were conducted in April (dry season) and August (wet season) 2018, the results showed that QNs was extensively distributed in the Baiyangdian Lake. For the occurrence, Flumequine (FLU) and Ofloxacin (OFL) were the most detected QNs in Baiyangdian Lake. For the temporal variation, the sum concentration of QNs in water and sediment were ranged from 153 ng/L to 3093 ng/L and from 40.1 ng/g to 1475 ng/g in April, while ranged from 3.83 ng/L to 769 ng/L and from 20.3 ng/g to 373 ng/g in August. For the spatial variation, all of QNs exhibited significance difference in concentration at different sampling areas. Furthermore, PNEC plays an important role in ecological risk assessment, thus the PNECs of FLU and OFL were derived by assessment factors (AF), species sensitivity distribution (SSD), and AQUATOX model methods. The results showed that: PNEC_AFs, PNEC_SSDs, and PNEC_AQUATOXs were 18.7 μg/L, 196 μg/L, and 128 μg/L for FLU, respectively; and were 0.021 μg/L, 4.40 μg/L, and 3.00 μg/L for OFL, respectively. The PNECs for FLU and OFL derived by three approaches showed the rank of: PNEC_SSDs > PNEC_AQUATOXs > PNEC_AFs; while the risk quotients (RQs) followed the other rank of: RQ_SSDs < RQ_AQUATOXs < RQ_AFs. The results was indicated that the indirect ecological effects plays an important role in the derived PNECs for QNs, without considering the indirect ecological effects in natural ecosystem can lead to under-protective or over-protective PNECs (RQs) for chemicals. Therefore, AQUATOX model can be applied in deriving PNECs during the ecological risk assessment.

Chronic effects of bisphenol S and bisphenol SIP on freshwater waterflea and ecological risk assessment

Bisphenol S (BPS) and 4-hydroxyphenyl 4-isoprooxyphenylsulfone (BPSIP) have been used as substitutes for bisphenol A (BPA) owing to increased regulation of BPA in plastics. In this study, long-term toxicity tests of BPS and BPSIP were performed using Daphnia magna and Moina macrocopa. The predicted no-effect concentration (PNEC) of BPA, BPS, and BPSIP were derived by the assessment factor (AF) method and the species sensitivity distribution (SSD) method. An ecological risk assessment was performed based on the measured environmental concentrations of BPA in surface water worldwide and the derived PNECs. The chronic NOEC of D. magna was 2.5 mg/L for BPS and 0.5 mg/L for BPSIP, and that of M. macrocopa was 0.03 mg/L for BPS and 0.1 mg/L for BPSIP. The PNEC_AF was generally one order of magnitude less than the PNEC_SSD, and the PNEC of BPS was 10 times lower than that of BPA. The hazard quotients of BPA and BPS exceeded 1, indicating that concentrations in ambient water conditions could pose a potential risk to aquatic organisms. Since the use of alternative compounds is increasing, further monitoring data of the water environment and chronic toxicity in various aquatic organisms appears to be necessary.

Occurrence and Risk Assessment of Steroidal Hormones and Phenolic Endocrine Disrupting Compounds in Surface Water in Cuautla River, Mexico

In this study, two hormones 17β-estradiol (E2) and 17α-ethynylestradiol (EE2), and three phenolic compounds, bisphenol A (BPA), 4-N-nonylphenol (4-NP) and 4-tert-octylphenol (4-t-OP), were determined in surface water in the Cuautla River at the State of Morelos during the dry-season in Mexico. The endocrine disrupting compounds (EDCs) were extracted from water samples using solid-phase extraction (SPE) with end-capped C18, and then the extracts were chemically derivatized to TMS (trimethylsylane)-compounds and analyzed by gas chromatography coupled to mass spectrometry (GCMS). The most abundant compound was BPA (22.46 ± 30.17 ng L−1), followed by 4-t-OP (11.24 ± 11.76 ng L−1), 4-NP (7.53 ± 14.88 ng L−1), EE2 (2.37 ± 4.36 ng L−1) and E2 (0.97 ± 1.82 ng L−1). The residual amounts of target compounds could either reach stream surface water from direct domestic wastewater discharges, conventional wastewater treatment plant or can be a result from the use of agrochemicals in crop areas. The EDCs in Cuautla River exerted a high pressure on the aquatic ecosystem because their presences in surface water caused medium and high potential ecological risk. Besides, it was found that aquatic organisms were exposed to estrogenic activity.

Occurrence, fate and toxic effects of the industrial endocrine disrupter, nonylphenol, on plants - A review

Nonylphenol (NP) and its detrimental effects on the environment, humans, wildlife, fish and birds is an increasingly important global research focus. The number of investigations on the toxicity and metabolic fate of NP in plants is however limited. This paper reviews the prevalence and source of NP in plants and the effect it has on its morphological, physiological and ultrastructural status. Fruit and vegetables have been found to contain levels of NP that is twenty-fold exceeding the no observable effect level (NOEL) of freshwater algae. Apart from the potential risk this poses to the health of consumers, it can overburden the plant's natural defence system, leading to growth disorders. Plants exposed to NP show signs of overall growth reduction, changes in organelle structure and oxidative damage. These adverse effects may exacerbate the food security dilemma faced by many countries and impede their progress towards attaining the sustainable development goals.

Distribution and ecological risk assessment of PEDCs in the water, sediment and Carex cinerascens of Poyang Lake wetland, China

Phenolic endocrine disrupting chemicals (PEDCs), such as 4-nonylphenol (NP), 4-t-octylphenol (OP), bisphenol A (BPA), and nonylphenol-di-ethoxylate (NP2EO), can cause feminization and carcinogenesis. This study assessed the distributions of NP, OP, BPA, and NP2EO in the water, sediment, and Carex cinerascens of Poyang Lake wetland. The four PEDCs were ubiquitous. The concentrations of NP and OP in the water and sediment of the wetland were significantly lower than those in other regions of China. Average BPA concentrations in the water, sediment, and Carex cinerascens samples were 40.49 ± 18.42 ng/L, 9.840 ± 3.149 ng/g, and 3.25 ± 1.40 ng/g, respectively; the BPA concentration in the water was similar to that of other rivers in China. Average NP2EO concentrations in the wetland were 3125.9 ± 478.1 ng/L, 650.0 ± 209.9 ng/g, and 275.8 ± 59.0 ng/g in the water, sediment, and Carex cinerascens samples, respectively. The predicted no-effect concentrations in sediment for NP, OP, BPA, and NP2EO were estimated to be 75.41, 45.25, 8.22, and 237.5 ng/g, respectively. The risk quotient (RQ) method was used to characterise the ecological risk from these PEDCs. A high ecological risk (RQ ≥ 1) from BPA was observed for 0%, 57.69%, and 5.00% of water, sediment, and C. cinerascens samples, respectively, while a high risk from NP2EO was observed for 71.43%, 96.15%, and 55.00% of samples. Ecological risk varied spatially. The high ecological risk from NP2EO in Poyang Lake wetland may be a result of non-point pollution from rural areas and sewage from Poyang Lake basin.

The utility of vitellogenin as a biomarker of estrogenic endocrine disrupting chemicals in molluscs

Estrogenic endocrine disrupting chemicals (EDCs) are natural hormones, synthetic compounds or industrial chemicals that mimic estrogens due to their structural similarity with estrogen's functional moieties. They typically enter aquatic environments through wastewater treatment plant effluents or runoff from intensive livestock operations. Globally, most natural and synthetic estrogens in receiving aquatic environments are in the low ng/L range, while industrial chemicals (such as bisphenol A, nonylphenol and octylphenol) are present in the μg to low mg/L range. These environmental concentrations often exceed laboratory-based predicted no effect concentrations (PNECs) and have been evidenced to cause negative reproductive impacts on resident aquatic biota. In vertebrates, such as fish, a well-established indicator of estrogen-mediated endocrine disruption is overexpression of the egg yolk protein precursor vitellogenin (Vtg) in males. Although the vertebrate Vtg has high sensitivity and specificity to estrogens, and the molecular basis of its estrogen inducibility has been well studied, there is growing ethical concern over the use of vertebrate animals for contaminant monitoring. The potential utility of the invertebrate Vtg as a biomonitor for environmental estrogens has therefore gained increasing attention. Here we review evidence providing support that the molluscan Vtg holds promise as an invertebrate biomarker for exposure to estrogens. Unlike vertebrates, estrogen signalling in invertebrates remains largely unclarified and the classical genomic pathway only partially explains estrogen-mediated activation of Vtg. In light of this, in the latter part of this review, we summarise recent progress towards understanding the molecular mechanisms underlying the activation of the molluscan Vtg gene by estrogens and present a hypothetical model of the interplay between genomic and non-genomic pathways in the transcriptional regulation of the gene.

Threats of organophosphate esters (OPEs) in surface water to ecological system in Haihe River of China based on species sensitivity distribution model and assessment factor model

Organophosphate esters (OPEs) are a kind of emerging contaminants, but the information about their pollution profile and ecological risk are still scarce in China. In this study, 31 surface water samples of Haihe River (China) were collected in November 2017, and 11 OPEs were measured, and the ecological risk of OPEs was assessed by means of species sensitivity distribution (SSD) method and assessment factor method. Additionally, Pearson correlation analysis and an international comparison with other rivers in the world were conducted. The results showed that total OPEs ranged from 23.98 to 824.72 ng L^-1, and the mean value was 228.70 ng L^-1. The concentration of OPEs decreased as follows: Tri(2-chloroisopropyl) phosphate (TCPP) > Tri(2-chloroethyl) phosphate (TCEP) > Triethyl phosphate (TEP) > Tributoxyethyl phosphate (TBEP) > Triphenyl phosphate (TPhP) > Tripropyl phosphate (TPrP) > Tri(2-ethylhexyl) phosphate (TEHP) > 2-ethylhexyl diphenyl phosphate (EHDPP) > Tri(1,3-dichloro-2-propyl)phosphate (TDCPP) > Tri-n-butyl phosphate (TnBP) > Tri-m-cresyl phosphate (TMPP). TCPP (19.54-160.82 ng L^-1) and TCEP (N.D.-151.99 ng L^-1) with the mean value of 76.67 and 53.13 ng L^-1 respectively were identified as the richest OPEs in Haihe River. The concentration of OPEs slowly increased in the upper reaches of Haihe River, and it tended to be stable in the middle reaches of Haihe River and decreased rapidly from the downstream to the outer sea. Significantly positive correlations occurred among three chlorinated alkyl OPEs (TCEP, TCPP, and TDCPP), suggesting that they might come from the same source. Based on the comparison, the pollution condition of OPEs in Haihe River was low, and TCEP was found to be the most abundant OPEs in China but it was not that in Europe. The ecological risk assessment on the basis of assessment factor method suggested that the risk of OPEs in Haihe River for algae, crustacean, and fish was limited. In addition, the results of SSD method suggested that the combined ecological risk of four OPEs in Haihe River was also low. This study provides information about the pollution status of OPEs in the surface water of China to some extents and a project for the risk estimation based on SSD for prior and emerging flame retardants.

Integrated regional ecological risk assessment of multiple metals in the soils: A case in the region around the Bohai Sea and the Yellow Sea

Methodology to quantify and distinguish the spatial distribution of the risks from multiple pollutants within the region was developed in this paper. An integrated quantitative risk assessment was conducted by utilizing a large amount of information available to explore spatial distribution of risk by single and multiple pollutants, and the magnitude of the overall risk from multiple pollutants based on the current concentrations of pollutants and toxicity data. Two target criteria levels - level I (NOEC/LOEC based) and level II (LC/EC/IC₅₀ based) - were employed, and thus, the regional and sub-regional risks were evaluated according to these two levels. The risk of multiple toxic metals (As, Cd, Cr, Hg and Pb) to a terrestrial ecosystem for the region around the Bohai Sea and the Yellow Sea were evaluated as a case. The total overall ecological risks from heavy metals in the region for level I and level II were 21.73% and 12.53%, respectively. The risks were ranked in the order of Cr > As > Pb > Cd > Hg with Cr posing the greatest ecological risk, which was 61.12% for level I. The top three cities according to the level II ecological risk were Cangzhou > Lianyungang > Panjin, while the top three cities of level I ecological risk were Cangzhou > Panjin > Lianyungang. This method provides a quantitative risk assessment with multiple and clear protection levels for risk management.

Water quality criteria derivation and ecological risk assessment for triphenyltin in China

Triphenyltin (TPT) is one of the most toxic chemicals artificially discharged into aquatic environment with human activities. Due to its intensive use in antifouling paints and adverse effects on non-target species, TPT has aroused wide concern in both saltwater and freshwater environment. Nevertheless, the water quality criteria (WQC) are not available in China, which impedes the risk assessment for this emerging pollutant. This study aims to establish the WQC of TPT for both freshwater and saltwater ecosystems. With the derived WQC, a four-level tiered ecological risk assessment (ERA) approach was employed to assess the ecological risks of this emerging pollutant in Chinese waters. Through the species sensitivity distribution (SSD) methodology, the freshwater criterion maximum concentration (CMC) and criterion continuous concentration (CCC) were derived as 396 ng Sn L^-1 and 5.60 ng Sn L^-1, respectively, whereas the saltwater CMC and CCC were 66.5 ng Sn L^-1 and 4.11 ng Sn L^-1, respectively. The ecological risk assessment for TPT demonstrated that the acute risk was negligible whereas the chronic risk was significant with HQ (Hazard Quotient) values of up to 5.669 and 57.1% of coastal waters in China facing clear risk. TPT contamination in coastal environment, therefore, warrants further concern.

Deriving predicted no-effect concentrations (PNECs) for emerging contaminants in the river Po, Italy, using three approaches: Assessment factor, species sensitivity distribution and AQUATOX ecosystem modelling

Over the past decades, per- and polyfluoroalkyl substances (PFASs) found in environmental matrices worldwide have raised concerns due to their toxicity, ubiquity and persistence. A widespread pollution of groundwater and surface waters caused by PFASs in Northern Italy has been recently discovered, becoming a major environmental issue, also because the exact risk for humans and nature posed by this contamination is unclear. Here, the Po River in Northern Italy was selected as a study area to assess the ecological risk posed by perfluoroalkyl acids (PFAAs), a class of PFASs, considering the noticeable concentration of various PFAAs detected in the Po waters over the past years. Moreover, the Po has a large environmental and socio-economic importance: it is the largest Italian river and drains a densely inhabited, intensely cultivated and heavily industrialized watershed. Predicted no-effect concentrations (PNECs) were derived using two regulated methodologies, assessment factors (AFs) and species sensitivity distribution (SSD), which rely on published ecotoxicological laboratory tests. Results were compared to those of a novel methodology using the mechanistic ecosystem model AQUATOX to compute PNECs in an ecologically-sound manner, i.e. considering physical, chemical, biological and ecological processes in the river. The model was used to quantify how the biomasses of the modelled taxa in the river food web deviated from natural conditions due to varying inputs of the chemicals. PNEC for each chemical was defined as the lowest chemical concentration causing a non-negligible yearly biomass loss for a simulated taxon with respect to a control simulation. The investigated PFAAs were Perfluorooctanoic acid (PFOA) and Perfluorooctanesulfonic acid (PFOS) as long-chained compounds, and Perfluorobutanoic acid (PFBA) and Perfluorobutanesulfonic acid (PFBS) as short-chained homologues. Two emerging contaminants, Linear Alkylbenzene Sulfonate (LAS) and triclosan, were also studied to assess the performance of the three methodologies for chemicals whose ecotoxicology and environmental fate are well-studied. The most precautionary approach was the use of AFs generally followed by SSD and then AQUATOX, except for PFOS, for which AQUATOX yielded a much lower PNEC compared to the other approaches since, unlike the other two methodologies, it explicitly simulates sublethal toxicity and indirect ecological effects. Our findings highlight that neglecting the role of ecological processes when extrapolating from laboratory tests to ecosystems can result in under-protective threshold concentrations for chemicals. Ecosystem models can complement existing laboratory-based methodologies, and the use of multiple methods for deriving PNECs can help to clarify uncertainty in ecological risk estimates.

Development of water quality criteria of ammonia for protecting aquatic life in freshwater using species sensitivity distribution method

Ammonia is deemed one of the most important pollutants in the freshwater environment because of its highly toxic nature and ubiquity in surface water. This study thus aims to derive the criteria for ammonia in freshwater to protect aquatic life because there are no water quality criteria for ammonia in Korea. Short-term lethal tests were conducted to perform the species sensitivity distribution (SSD) method. This method is widely used in ecological risk assessment to determine the chemical concentrations to protect aquatic species. Based on the species sensitivity distribution method using Korean indigenous aquatic biota, the hazardous concentration for 5% of biological species (HC₅) value calculated in this study was 44mg/L as total ammonia nitrogen (TAN). The value of the assessment factor was set at 2. Consequently, the criteria for ammonia were derived as 22mg/L at pH7 and 20°C. When the derived value was applied to the monitoring data nationwide, 0.51%, 0.09%, 0.18%, 0.20%, and 0.35% of the monitoring sites in Han River, Nakdong River, Geum River, Youngsan River, and lakes throughout the nation, respectively, exceeded this criteria. The Ministry of Environment in Korea has been considering introducing water quality standard of ammonia for protecting aquatic life. Therefore, our results can provide the basis for introducing the ammonia standard in Korea.

Contamination and risk implications of endocrine disrupting chemicals along the coastline of China: A systematic study using mussels and semipermeable membrane devices

A systematic study has been carried out to assess the contamination of endocrine disrupting chemicals (EDCs) in five highly urbanized coastal cities spanning from temperate to subtropical environments along the coastline of China. In each of these cities, species of native mussels (Mytilus galloprovincialis, M. coruscus or Perna viridis) were deployed alongside with semipermeable membrane devices (SPMDs) for one month at a reference site and a polluted site. The level of 4-nonylphenol (4-NP), bisphenol A (BPA), 17β-estradiol (E2) and 17α-ethynylestradiol (EE2) in SPMDs and transplanted mussels were determined and compared. The concentration of EDCs in mussels from polluted sites of Qingdao and Shenzhen ranged from 99.4±9.40 to 326.1±3.16ng/g dry wt. for 4-NP, Dalian and Shanghai from 170.3±4.00 to 437.2±36.8ng/g dry wt. for BPA, Dalian and Shenzhen from 82.9±3.03 to 315.6±6.50ng/g dry wt. for E2, and Shenzhen and Shanghai from 124.5±3.25 to 204.5±9.26ng/g dry wt. for EE2, respectively. These results demonstrate that concentrations of EDCs in mussels along the coastline of China are substantially higher than levels reported in mussels and seafood elsewhere. Despite high levels of EDCs and per capita seafood consumption in China, analysis indicated that 4-NP and BPA intake from mussels at polluted sites per se are still below the Tolerable Daily Intake (TDI). In contrast, the daily intake of E2 and EE2 (6.5 and 5.5μg/person/day, respectively) from mussel consumption exceeded the Acceptable Daily Intake (ADI) established by the WHO, USA and Australia by large margins, suggesting significant public health risks. A strong correlation was found between EDC concentrations in SPMDs and transplanted mussels, and the advantages of using mussels and SPMDs for monitoring EDCs in the aquatic environment are discussed.