Tiered aquatic ecological risk assessment of organochlorine pesticides and their mixture in Jiangsu reach of Huaihe River, China

Advancing exposure assessment approaches to improve wildlife risk assessment

The exposure assessment component of a Wildlife Ecological Risk Assessment aims to estimate the magnitude, frequency, and duration of exposure to a chemical or environmental contaminant, along with characteristics of the exposed population. This can be challenging in wildlife as there is often high uncertainty and error caused by broad-based, interspecific extrapolation and assumptions often because of a lack of data. Both the US Environmental Protection Agency (USEPA) and European Food Safety Authority (EFSA) have broadly directed exposure assessments to include estimates of the quantity (dose or concentration), frequency, and duration of exposure to a contaminant of interest while considering "all relevant factors." This ambiguity in the inclusion or exclusion of specific factors (e.g., individual and species-specific biology, diet, or proportion time in treated or contaminated area) can significantly influence the overall risk characterization. In this review, we identify four discrete categories of complexity that should be considered in an exposure assessment-chemical, environmental, organismal, and ecological. These may require more data, but a degree of inclusion at all stages of the risk assessment is critical to moving beyond screening-level methods that have a high degree of uncertainty and suffer from conservatism and a lack of realism. We demonstrate that there are many existing and emerging scientific tools and cross-cutting solutions for tackling exposure complexity. To foster greater application of these methods in wildlife exposure assessments, we present a new framework for risk assessors to construct an "exposure matrix." Using three case studies, we illustrate how the matrix can better inform, integrate, and more transparently communicate the important elements of complexity and realism in exposure assessments for wildlife. Modernizing wildlife exposure assessments is long overdue and will require improved collaboration, data sharing, application of standardized exposure scenarios, better communication of assumptions and uncertainty, and postregulatory tracking. Integr Environ Assess Manag 2024;20:674-698. © 2023 SETAC.

Ecological risk assessment of heavy metals in desulfurized seawater discharged from a coal-fired power plant in Qingdao

Despite the prevalence of discharge of large volumes of heavy-metal-bearing seawater from coal-fired power plants into adjacent seas, studies on the associated ecological risks remain limited. This study continuously monitored concentrations of seven heavy metals (i.e. As, Cd, Cr, Cu, Hg, Pb, and Zn) in surface seawater near the outfall of a coal-fired power plant in Qingdao, China over three years. The results showed average concentrations of As, Cd, Cr, Cu, Hg, Pb, and Zn of 2.63, 0.33, 2.97, 4.63, 0.008, 0.85, and 25.00 μg/L, respectively. Given the lack of data on metal toxicity to local species, this study investigated species composition and biomass near discharge outfalls and constructed species sensitivity distribution (SSD) curves with biological flora characteristics. Hazardous concentrations for 5% of species (HC5) for As, Cd, Cr, Cu, Hg, Pb, and Zn derived from SSDs constructed from chronic toxicity data for native species were 3.23, 2.22, 0.06, 2.83, 0.66, 4.70, and 11.07 μg/L, respectively. This study further assessed ecological risk of heavy metals by applying the Hazard Quotient (HQ) and Joint Probability Curve (JPC) based on long-term heavy metal exposure data and chronic toxicity data for local species. The results revealed acceptable levels of ecological risk for As, Cd, Hg, and Pb, but unacceptable levels for Cr, Cu, and Zn. The order of studied heavy metals in terms of ecological risk was Cr > Cu ≈ Zn > As > Cd ≈ Pb > Hg. The results of this study can guide the assessment of ecological risk at heavy metal contaminated sites characterized by relatively low heavy metal concentrations and high discharge volumes, such as receiving waters of coal-fired power plant effluents.

Distribution, sources and health risk assessment of DDT and its metabolites in agricultural soils in Zhejiang Province, China

Dichlorodiphenyltrichloroethane (DDT) is well known for its harmful effects and has been officially banned as a pesticide around the world. However, DDT pollution still exists in natural environments in China because DDT degrade very slowly. In this study, 60 soil samples were collected from Cixi, Zhejiang Province, and the levels of DDTs and its metabolites in soil and health risks were investigated. The results showed that the detection rate of DDT in soil samples were 100%, and the total DDTs residue in soil ranged from 0.007 to 1.208 mg/kg, with an average of 0. 113±0. 035 mg/kg, which exceeded the second-level Chinese soil environmental quality standard for farmland soil. The average residuals of p,p'-DDT, p,p'-DDE (dichlorodiphenyldichloroethylene), p,p'-DDD (dichlorodiphenyldichloroethane) and o,p'-DDT accounted for 34.8%, 50.9%, 8.0% and 6.3% of the total DDTs, respectively. The DDD/DDE ratios indicated a dehydrochlorination of DDT to DDE under aerobic conditions at most sampling sites. The ratios of (p,p'-DDE+p,p'-DDD)/p,p'-DDT and o,p'-DDT/p,p'-DDT indicating the DDT in the field were mainly introduced via industrial DDT and dicofol, including historical residue and fresh input. The health risk assessment showed that DDT-contaminated sites do not pose a non-carcinogenic risk to humans, and pose a very low risk of cancer to children and a low risk of cancer to adults. Overall, this study helps to understand the distribution, sources and health risks of DDT in typical soils.

Aquatic ecological risk assessment of imidacloprid and thiacloprid in an urban river of Qingdao, China

Imidacloprid and thiacloprid, two neonicotinoid insecticides that are extensively used in urban areas, are potentially toxic to non-target aquatic organisms. In this study, the concentrations of imidacloprid and thiacloprid in surface runoff after rainfall were 20.79-43.77 ng/L and 25.13-63.84 ng/L, respectively, whereas the levels for the Licun River were 10.78-41.70 ng/L and 2.66-39.68 ng/L, respectively. The acute and chronic criteria for imidacloprid and thiacloprid are 0.865, 0.006, 0.83, and 0.012 μg/L, respectively. Tiered ecological risk assessments revealed the chronic ecological risks of these micropollutants to local aquatic species. There was a moderate chronic toxicity risk associated with imidacloprid and thiacloprid in the Licun River, and the joint probability curves showed a probability of chronic ecological risk to 5 % of the aquatic organisms at 68 %-97 %. The results provide evidence of urban surface runoff transporting micropollutants from surface into rivers and estuaries, highlighting the ecological risks to aquatic ecosystems.

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.

Water quality criteria derivation and ecological risk assessment for organophosphorus pesticides

Organophosphorus pesticides (OPPs) are a group of neurotoxic compounds that can cause neural dysfunction, overstimulation, paralysis, and even death to numerous non-target organisms. Despite their potential ecological impacts, there is a lack of research on water quality criteria (WQC) for OPPs, which hinders the risk assessment for these pollutants. This study aimed to derive short-term and long-term water quality criteria (SWQC and LWQC, respectively) for eight common OPPs through the species sensitivity distribution (SSD) methodology. The ecological risk of these compounds in aquatic environments was consequently assessed using a four-level tiered approach. The results showed that the derived SWQC ranged from 0.0245 μg/L (chlorpyrifos) to 18.6 μg/L (dimethoate), while the LWQC ranged from 0.326 ng/L (chlorpyrifos) to 0.354 μg/L (dimethoate). OPPs were widely recorded in different waters with concentrations up to 40.9 μg/L. The tiered approach results indicated that most OPPs had a low acute risk but a severe chronic risk. The estimated chronic hazard quotients (HQ) were calculated with a maximum of 4782, the exceedance probabilities with a maximum of 97.6%, and the overall probabilities (ORP) with a range of between 0.08% and 11.5%. These findings suggest that the contamination of OPPs in aquatic environments warrants further concern.

Ecological risk of phenol on typical biota of the northern Chinese river from an integrated probability perspective: the Hun River as an example

Phenol, known for its bioaccumulative nature and severe toxicity to riverine organisms, poses complex challenges for ecological risk assessment. To tackle this issue, we developed a three-stage incremental assessment method, providing an integrated perspective on phenol toxicity risk for aquatic organisms. The findings indicated that phenol concentrations were generally higher in the aquatic environments of northern rivers, such as the Hun River, Taizi River, and Liao River, compared to those in southern China. The evaluation results at individual points showed that the ecological risk of phenol to aquatic organisms ranked from high to low during rainy, dry, and normal seasons, showing seasonal variation characteristics. Regarding spatial variation along the river, the ecological risk of phenol gradually increased from upper reaches, peaked in the middle reaches, and then decreased in the lower reaches. Considering the different species types, fish face a higher risk of toxic effects of phenol than invertebrates when exposed to phenol over a long period of time, probably due to the bioaccumulative nature of phenol. To address ecological risk control at the watershed scale, there is an urgent need to revise China's current river water quality standards. It is essential to increase the emphasis on ecological risk control for aquatic organisms. Developing more targeted and refined ecological risk control strategies for river phenols is crucial to maintain a healthier and more vibrant river ecosystem.

Risk assessment of bisphenol analogues towards mortality, heart rate and stress-mediated gene expression in cladocerans Moina micrura

Bisphenol A (BPA) is a well-known endocrine-disrupting compound that causes several toxic effects on human and aquatic organisms. The restriction of BPA in several applications has increased the substituted toxic chemicals such as bisphenol F (BPF) and bisphenol S (BPS). A native tropical freshwater cladoceran, Moina micrura, was used as a bioindicator to assess the adverse effects of bisphenol analogues at molecular, organ, individual and population levels. Bisphenol analogues significantly upregulated the expressions of stress-related genes, which are the haemoglobin and glutathione S-transferase genes, but the sex determination genes such as doublesex and juvenile hormone analogue genes were not significantly different. The results show that bisphenol analogues affect the heart rate and mortality rate of M. micrura. The 48-h lethal concentration (LC₅₀) values based on acute toxicity for BPA, BPF and BPS were 611.6 µg L^-1, 632.0 µg L^-1 and 819.1 µg L^-1, respectively. The order of toxicity based on the LC₅₀ and predictive non-effect concentration values were as follows: BPA > BPF > BPS. Furthermore, the incorporated method combining the responses throughout the organisation levels can comprehensively interpret the toxic effects of bisphenol analogues, thus providing further understanding of the toxicity mechanisms. Moreover, the output of this study produces a comprehensive ecotoxicity assessment, which provides insights for the legislators regarding exposure management and mitigation of bisphenol analogues in riverine ecosystems.

Occurrence, distribution, and ecological risk of bisphenol analogues in marine ecosystem of urbanized coast and estuary

Bisphenol analogues are prevalent globally because of rampant usage and imprecise processing techniques, prompting alerts about environmental and health hazards. The method employed in this study by solid phase extraction (SPE) and liquid chromatography-tandem quadrupole mass spectrometer (LC-MS/MS) for both quantification and qualitative analysis of the bisphenol compounds in the surface water samples. The coastal and estuarine surface water of Port Dickson and Lukut ranges from 1.32 ng/L to 1890.51 ng/L of bisphenol analogues. BPF mean concentration at 1143.88 ng/L is the highest, followed by BPA and BPS at 59.01 ng/L and 10.96 ng/L, respectively. Based on RQm for bisphenol analogues, the highest for BPF at 2.49 (RQ > 1, high risk), followed by BPS at 0.12 (0.1 < RQ < 1, medium risk) and BPA at 0.09 (0.1 < RQ < 1, medium risk). The presence and current risk of bisphenols analogues should alert the possible water quality degradation soon.

Constructing model-averaging species sensitivity distributions of Phenanthrene based on reproductive fitness: Implications for assessing ecological risk in urban watershed

The challenge in optimizing the method of constructing species sensitivity distribution (SSD) remains. In this study, a model-averaging SSD was created to evaluate the ecological risk of Phenanthrene (PHE) in urban watershed based on reproductive fitness. Specifically, concentrations of PHE were measured in surface water samples collected from various watersheds of Wuhan, including five lake watersheds and the Wuhan reach of the Yangtze River and Han River. The reproductive endpoint of aquatic species was calculated to be most sensitive to PHE exposure, with the value of predict no-effect concentration (PNEC) at 0.19 μg/L. The results of probabilistic assessment methods, including joint probability curve (JPC), overall risk probability (ORP), and distribution-based quotient (DBQ), indicated that the ecological risks of PHE in large lakes have dropped significantly with distance from the downtown area of Wuhan, and the long-term effects of industrial activities may increase the risks in the lake watersheds. Basically, the ecological risks in Yangtze River are negligible; however, there is a relatively high risk of PHE in the Han River and some lake watersheds. The cos θ similarity analysis indicated the Yangtze River is strongly connected to the low-risk lake watersheds, and that in part reflects the risk in the Yangtze River being controlled by its surrounding these lake watersheds.

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.

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.

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.

Deriving freshwater guideline values for neonicotinoid insecticides: Implications for water quality guidelines and ecological risk assessment

The increased use of neonicotinoid insecticides in aquatic environments poses a significant threat to non-target freshwater species. However, the existing water quality guidelines (WQGs) for neonicotinoids mainly focus on imidacloprid, and only a few authoritative institutions have established WQGs for other neonicotinoids. There is a critical need to develop WQGs and conduct ecological risk assessment (ERA) of different neonicotinoids in global freshwater environments. In this study, we derived interim acute and chronic guideline values and acute-to-chronic ratios (ACRs) for six neonicotinoids based on publicly available acute and chronic toxicity data. The exposure concentrations of neonicotinoids were obtained from published literature worldwide, and ERA was conducted for neonicotinoids in global freshwater ecosystems using a tiered approach. The derived chronic guideline values (95% confidence interval (CI), ng/L) were 0.63 (0.02-5.47) for thiacloprid (the lowest) and 16.4 for dinotefuran (the highest). The identified ACRs (95% CI) ranged from 90.9 (47.0-180) to 957 (102-3350), which can be used to extrapolate scarce chronic data from the acute data. Neonicotinoid concentrations in global freshwater were predicted from 10.6 (6.88-23.4) (thiacloprid) to 339 (211-786) ng/L (thiamethoxam). The estimated risk quotients ranged from 3.23 (dinotefuran) to 21.73 (thiacloprid), and the probability of exceeding WQGs ranged from 27.1% (dinotefuran) to 77.1% (thiacloprid). The ERA results indicated that the six neonicotinoids posed negligible acute risks but high chronic risks to global freshwater ecosystems, especially acetamiprid (65.8%) and thiacloprid (28.1%). The key findings of this study provide critical scientific information regarding the ecological risks of long-term neonicotinoid exposure and key insights for policy development and water quality control.

Organochlorine pesticides in riparian soils and sediments of the middle reach of the Huaihe River: A traditional agricultural area in China

Distributions, souces, ecological risks as well as environmental behaviors of 20 organochlorine pesticides (OCPs) in riparian soils and sediments of the middle reach of the Huaihe River, a traditional agricultural area of China, were investigated. ∑OCPs in riparian soils and sediments were 1.8-63 ng g^-1 (mean = 19 ± 12 ng g^-1) and 1.2-9.9 ng g^-1 (mean = 3.0 ± 1.8 ng g^-1), respectively. HCHs were the dominant OCPs in both soils and sediments, while high concentrations of ∑HEPTs and ∑DDTs were also detected in some soils and sediments. No correlations were found between concentrations of OCPs and organic matter contents in both soils and sediments. Based on the source analysis, most OCPs in the riparian soils were mainly from historical residues, such as historical usage of technical HCH, DDT, chlordane and endosulfan. OCPs in sediments were influenced not only by surface runoff by also by other factors, e.g. in-situ contamination (DDT-containing antifouling paints in ships) and/or hydraulic transport from some tributaries. Some never-used OCPs, such as heptachlor and aldrin, were widely detected in soils and sediments. This might be attributed to some unknown usages or long-range atmospheric transport of them from other source regions. Ecological risk analysis suggested that DDTs and HCHs in soils would not lead to an adverse effect on soil ecological environment as well as agricultural production, and OCP residues in sediments also would not pose a threat to the sediment-dwelling organisms.

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.

Research on freshwater water quality criteria, sediment quality criteria and ecological risk assessment of triclosan in China

Triclosan (TCS) is a broad-spectrum antimicrobial agent commonly used in pharmaceuticals and personal care products (PPCPs). The widespread use of TCS makes it frequently detected in various environmental mediums. In view of the high detection frequency of TCS in the aquatic environment and sediments, and its toxic effects on aquatic species, it is critical and necessary to derive Chinese TCS water quality criteria (WQC) and sediment quality criteria (SQC) for protecting Chinese aquatic organisms, and perform the ecological risk assessment. In fact, former research had derived the WQC of TCS mainly based on acute and chronic toxicity data. As an endocrine disrupting chemical (EDC), TCS poses adverse effects on the growth, development and reproduction of aquatic organisms at much lower concentration. Considering nonlethal endpoints are sensitive endpoints for EDCs, TCS long-term water quality criteria (LWQC) was derived based on reproduction and growth related endpoints. In this work, the acute toxicity data of 19 aquatic organisms and the chronic toxicity data of 15 aquatic organisms were obtained through collection and screening. The best fitting model of species sensitivity distribution (SSD) models including Normal, Log-Normal, Logistic and Log-Logistic of toxicity data was selected to derive WQC. The short-term and long-term WQC of TCS for Chinese aquatic organisms were 6.22 μg/L and 0.25 μg/L, respectively. Furthermore, through the phase-equilibrium partitioning method, SQC was derived based on WQC. SQC-low (SQC-L) and SQC-high (SQCH) were 0.13 mg/kg and 3.26 mg/kg, respectively. Moreover, the exposure concentration (EPC) data of TCS in Chinese rivers and sediments were collected. And through the hazard quotient (HQ) method and the joint probability curve (JPC) method we found that there were certain TCS ecological risks in Chinese rivers and sediments. Our work will provide a valuable reference for protecting aquatic organisms and minimizing TCS ecological risk in China.

A new insight into the ARG association with antibiotics and non-antibiotic agents-antibiotic resistance and toxicity

Although concerns have been raised about co-selection for antibiotic resistance and various antibiotics and non-antibiotic agents, the data on their association in urban sludge is still limited. In addition, antibiotic contamination can result in not only the toxicity but also the antibiotic resistance. In this study, the first large-scale identification of antibiotics and non-antibiotic agents concern for co-selection of resistance against antibiotics was conducted in urban sludge. Co-occurrence analysis showed that antibiotic resistance genes (ARGs) had no significant correlation with the corresponding antibiotics. Therefore, the results of co-occurrence analysis based on antibiotic concentration and ARG abundance were always ambiguous and difficult to interpret. However, antibiotic resistance was positively correlated with highly toxic compounds such as diclofenac, enrofloxacin and nicotine, suggesting that environmental contaminants might influence antibiotic resistance while exerting toxicity through mechanisms such as changes in microbial community and enzyme activity. The close correlation between class 1 integrase gene (intI1) and diclofenac/enrofloxacin indicated that the co-selection scenario between environmental contaminants and ARGs was likely mediated via intI1. In total, the derived co-occurrence patterns improve our understanding of the co-selection between ARGs, antibiotics and non-antibiotic agents, and also reaffirm the importance of potential role of non-antibiotic agents in the global spread of antibiotic resistance.

Occurrence, spatial distribution, and fate of polycyclic musks in sediments from the catchment of Chaohu Lake, China

Twenty-nine surface sediments from Chaohu Lake in China and from its six main tributaries were sampled to investigate the concentrations of two important polycyclic musks (PCMs), 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta(g)-2-benzopyran (galaxolide, HHCB) and 7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene (tonalide, AHTN), as well as the concentration of 4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta(g)-2-benzopyran-1-one (galaxolidon, HHCB-lactone), which is the main degradation product of HHCB. Except for the high concentrations of AHTN and HHCB measured in the Nanfei River (879 ng/g dw and 5,513 ng/g dw, respectively), the levels of AHTN and HHCB in the river sediments were 7.08-44.9 ng/g dw and 20.6-268 ng/g dw, respectively, which are slightly lower than those documented in various areas worldwide. The concentrations of AHTN and HHCB in the sediments of Chaohu Lake were one or two orders of magnitude lower than those in the tributary rivers and showed a clear regional distribution. The concentrations of HHCB-lactone were comparable to those of HHCB and presented a significant positive correlation with the concentrations of HHCB, suggesting that the HHCB-lactone originated directly from the degradation of HHCB in wastewater treatment plants (WWTPs) or in the natural environment. The diagnostic ratios of HHCB/AHTN and HHCB-lactone/HHCB and the enantiomeric fractions (EFs) of these PCMs showed that the direct origins of the target PCMs in the study area were municipal and industrial wastewaters discharged from adjacent cities or point sources and that the HHCB-lactone in sediment originated from the natural degradation of HHCB in the rivers and the lake. The results of the risk assessment showed that the PCMs in the watershed sediments were unlikely to pose a threat to aquatic species. However, the effluents of industrial and municipal wastewaters that are discharged into the Nanfei River should be investigated in future research.

Seawater contamination associated with in-water cleaning of ship hulls and the potential risk to the marine environment

In-water cleaning can clear-off foulants from ship hulls to prevent transportation of non-indigenous species and reduce hull friction and consequent fuel use. However, during cleaning, antifouling paint residues containing toxic substances can be released into the environment. To understand the potential risks of in-water hull cleaning, cleaning effluents were collected and analyzed for total suspended solid (TSS), particle size distribution, and metal concentrations. TSS concentrations were 97.3-249 mg/L, corresponding to release rates of 12.9-37.5 g/m² from the hull surface. Particles with sizes of ≥8 μm contributed 75-94% of the TSS. Average Cu and Zn concentrations in the effluents were 209 μg/L and 1510 μg/L, respectively, which were used for risk assessment in two port scenarios. Although the risks vary with the scale of the hull cleaning and the ports, in-water cleaning poses clear risks to marine environments, unless the effluents are recovered or treated before being released.

Ecological risk assessment of pesticide residues in soils from vegetable production areas: A case study in S-Nepal

Pesticides pose a serious risk to ecosystems. In this study, we used European Food Safety Authority methods, such as risk quotient (RQ) and toxicity exposure ratios (TER), to assess the potential ecological risks of 15 pesticide residues detected in agricultural soils in the Gaidahawa Rural Municipality of Nepal. The mean and maximum concentrations of the detected pesticide residues in the soil were used for risk characterization related to soil organisms. RQ_mean, TER_mean and RQ_maximum, TER_maximum were used to determine general and the worst-case scenarios, respectively. Of all the detected pesticides in soils, the no observed effect concentration (NOEC) for 27% of the pesticides was not available in literature for the tested soil organisms and their TER and RQ could not be calculated. RQ threshold value of ≥1 indicates high risk for organisms. Similarly, TER threshold value of ≥5, which is acceptable trigger point value for chronic exposure, indicates an acceptable risk. The results showed that the worst-case scenario (RQ_maximum) indicated a high risk for soil organisms from chlorpyrifos [RQ_maximum > 9 at depths (cm) of 0-5, 15-20 and 35-40 soil layer]; imidacloprid (1.78 in the 35-40 cm soil layer) and profenofos (3.37 in the 0-5 cm and 1.09 in the 35-40 cm soil layer). Likewise, for all the soil depths, the calculated TER for both the general and worst-case scenarios for chlorpyrifos ranged from 0.37 to 3.22, indicating chronic toxicity to F. candida. Furthermore, the risk of organophosphate pesticides for soil organisms in the sampling sites was mainly due to chlorpyrifos, except for two study sites where the risk was from profenofos. Ecological risk assessment (EcoRA) of the pesticide use in the study area indicated that the EFSA soil organisms were at risk at some of the localities where farmers practiced conventional farming.

Accumulation and risk assessment of heavy metals employing species sensitivity distributions in Linggi River, Negeri Sembilan, Malaysia

The constant increase of heavy metals into the aqueous environment has become a contemporary global issue of concern to government authorities and the public. The study assesses the concentration, distribution, and risk assessment of heavy metals in freshwater from the Linggi River, Negeri Sembilan, Malaysia. Species sensitivity distribution (SSD) was utilised to calculate the cumulative probability distribution of toxicity from heavy metals. The aquatic organism's toxicity data obtained from the ECOTOXicology knowledgebase (ECOTOX) was used to estimate the predictive non-effects concentration (PNEC). The decreasing sequence of hazardous concentration (HC₅) was manganese > aluminium > copper > lead > arsenic > cadmium > nickel > zinc > selenium, respectively. The highest heavy metal concentration was iron with a mean value of 45.77 μg L^-1, followed by manganese (14.41 μg L^-1) and aluminium (11.72 μg L^-1). The mean heavy metal pollution index (HPI) value in this study is 11.52, implying low-level heavy metal pollutions in Linggi River. The risk quotient (RQ) approaches were applied to assess the potential risk of heavy metals. The RQ shows a medium risk of aluminium (RQ_m = 0.1125) and zinc (RQ_m = 0.1262); a low risk of arsenic (RQ_m = 0.0122) and manganese (RQ_m = 0.0687); and a negligible risk of cadmium (RQ_m = 0.0085), copper (RQ_m = 0.0054), nickel (RQ_m = 0.0054), lead (RQ_m = 0.0016) and selenium (RQ_m = 0.0012). The output of this study produces comprehensive pollution risk, thus provides insights for the legislators regarding exposure management and mitigation.

Synthetic musk fragrances in sediments from a subtropical river-lake system in eastern China: occurrences, profiles, and ecological risks

Synthetic musk fragrances (SMFs) in aquatic environments have been of increasing concern because of their potential characteristic of persistent, bioaccumulated, and ecological harm. However, little is known about the distribution of SMFs in river-lake systems. In this study, the occurrence and risks of six SMFs measured in sediments from Lake Chaohu (eastern China) and the rivers flowing into it were investigated. The total sedimentary SMF concentrations ranged from 2.43 to 15.5 ng/g in Lake Chaohu (median = 5.17 ng/g), and 2.34-104 ng/g in the rivers (median = 10.6 ng/g). Overall, moderate levels of SMFs were found in comparison with previous results from other areas. Galaxolide and tonalide dominated in the rivers whereas cashmeran was dominant in Lake Chaohu. A source assessment indicated that the discharge from industries contributed importantly to the pollution of SMFs in the studied waters, in addition to the inputs from domestic sewage. Our estimates suggested that the current sedimentary SMF concentrations were likely to pose extremely low ecological risk to aquatic organisms. However, more studies are needed to focus on the spatial and temporal trends in distribution as well as the ecotoxicological implications of SMFs in the Lake Chaohu area because there is a general lack of relevant information.

Exposure and tiered ecological risk assessment of phthalate esters in the surface water of Poyang Lake, China

Phthalate esters (PAEs) are a class of endocrine disruptors that are produced and used extensively in China. Given its presence in various products, a great quantity of PAEs flows into different aquatic systems each year. Hence, it is important to study the pollution levels and ecological risk of PAEs. This study investigated the distribution and seasonal variation of six priority PAEs in the surface water of Poyang Lake, the largest freshwater lake in China. In the wet season, the mean concentration of the total PAEs was 0.544 ± 0.173 μg/L, while the dry season concentration (1.003 ± 0.451 μg/L) nearly doubled. The most abundant PAE congeners were di-n-butyl phthalate (DBP), followed by bis (2-ethylhexyl) phthalate (DEHP). To evaluate the ecological risks in Poyang Lake, the predicted no-effect concentrations (PNECs) of four PAEs based on non-lethal effects were derived. For diethyl phthalate (DEP), butyl benzyl phthalate (BBP), DBP, and DEHP, the PNECs were 31.6, 3.30, 2.31, and 0.0210 μg/L, respectively. The tiered ecological risk assessment showed that DEP and BBP posed no risk in Poyang Lake. Meanwhile, DBP posed a potential risk in Poyang Lake, but the risk of DEHP was unacceptable and requires more actions. Specifically, the probabilities of exceeding the threshold for the protection of 95% of the aquatic organisms (HC₅) were 3.30% and 4.43% for DEHP in the wet and dry season, respectively. This study provides an appropriate reference for the surface water management of PAE pollution in China.

Deterministic Assessment of the Risk of Phthalate Esters in Sediments of U-Tapao Canal, Southern Thailand

This baseline study evaluated the ecological risk associated with the concentration of six common Phthalate esters (PAEs) in sediment samples collected from the U-Tapao canal in Southern Thailand. Deterministic approaches consisting of standard sediment quality guidelines (SQGs) and Risk quotient (RQ) were used to evaluate the potential ecological risk of individuals and a mixture of Phthalate esters (PAEs) detected in sediment samples. Of the 6 PAEs measured, only three, including di-n-butyl phthalate (DBP), di-2-ethyl hexyl phthalate (DEHP) and di-isononyl phthalate (DiNP), were identified and quantified. The total concentration of the 3 PAEs congeners found in the sediment samples ranged from 190 to 2010 ng/g dw. The results from the SQGs and RQ were not consistent with each other. The SQGs results for individual PAEs showed that DEHP and DBP found in sediment was estimated to cause moderate risk on benthic organisms, DiNP was not estimated due to lack of SQGs data. However, the RQ method indicated a low risk of DEHP and DBP on algae, crustacean and fish, whereas DiNP poses no risk on crustacean. Furthermore, based on the result obtained in this study, the consensus SQGs for mixture effects prove to be a more protective tool than the RQ concentration addition approach in predicting mixture effects. Despite inevitable uncertainties, the integration of several screening approaches of ecological risk assessment (ERA) can help get a more inclusive and credible result of the first tier of individuals and a mixture of these pollutants.

Ecological and health risk assessment of perfluorooctane sulfonate in surface and drinking water resources in China

Perfluorooctane sulfonate (PFOS) is a synthetic substance with a great number of applications. However, it persists in the environment and is potentially toxic to organisms. Although China has been the main manufacturer and consumer for PFOS, the national pollution level and potential risk of this chemical are yet to be determined. This study aimed to provide an overview of PFOS contamination in surface and drinking water across China and to assess the potential ecological and health risks. Available monitoring data for PFOS in surface and drinking water were evaluated. PFOS was found to be ubiquitous in China, but the overall level of contamination was low compared with that in other countries. The southeast coastal area of China, with major PFOS-related companies, was characterized by relatively high PFOS exposure concentrations. The most sensitive effects was screened and applied to assess the ecological risk using the joint probability curve method. The probability of exceeding the growth and development toxicity for 5% of aquatic species was 0.65% in Chinese surface waters, while the highest probability of 0.90% was in Tai Lake in east China. Considering the average daily dose (ADD) for the Chinese population, the health risk posed by PFOS through drinking water ranged from 1.31 × 10^-4 to 13.91. Besides the relatively high health risk existed in east China, most health risks in China were acceptable.

History traces of HCHs and DDTs by groundwater dating and their behaviours and ecological risk in northeast China

Organochlorine pesticides legacies, such as hexachlorocyclohexane (HCH) and dichlorodiphenyltrichloroethane (DDT), remained in sediments or soils due to their difficulty in decomposition, especially in the agricultural areas where pesticides were widely used historically. Different from the little disturbed depositional environment of lake, it was difficult for rivers to explore the timing of DDT and HCH inputs through dating sediment cores as records. Based on groundwater dating, this study ascertained the historic pollution of DDT and HCH in Taizi River basin. HCH and DDT residues in groundwater were consistent with the historical production and usage, which increased from the 1950s to the 1980s and declined from the 1980s to the 1990s. Moreover, the partitioning behaviours of HCHs and DDTs in surface water and suspended particulate matter were discussed. It was revealed that β-HCH and o,p'-DDT were more likely to attach to suspended particulate matter than other isomers. Furthermore, species sensitivity distribution curves were generated using 54 toxicity data records to assess the risk of HCHs and DDTs in water and suspended particulate matter. These results indicated that p,p'-DDT in surface water posed a high risk to 95% of the aquatic life in the long run.

Polycyclic musks in surface water and sediments from an urban catchment in the megacity Beijing, China

Two typical polycyclic musks (PCMs), namely 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta-(g)-2-benzopyran (HHCB) and 7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene (AHTN), were determined in 63 surface water and 42 sediment samples collected from the North Canal River watershed, an urban catchment located in the megacity Beijing, China. Concentrations of HHCB and AHTN were 13.2 ng/L-395 ng/L and 2.98 ng/L-232 ng/L in surface water, while 4.10 ng/g-818 ng/g and 1.21 ng/g-731 ng/g in sediments. The results showed that PCM concentrations in the North Canal River watershed were at the high end when compared to that in other regions in China and worldwide. A watershed-wide annual mass budget showed that HHCB (∼150 kg/year) and AHTN (∼80 kg/year) mainly originated from urban wastewaters. Both PCMs were eliminated primarily by outflowing water (72 kg/year and 43 kg/year for HHCB and AHTN, respectively) and due to losses to the atmosphere (40 kg/year and 26 kg/year for HHCB and AHTN, respectively). An assessment of ecological risks posed by HHCB and AHTN to aquatic organisms in the North Canal River watershed was performed by using a tiered ecological risk assessment. The results showed that PCMs were unlikely to pose an ecological risk at the watershed scale (the probability of the incidence of adverse effect was <3.5% at the 99% protection level). However, according to the results from the risk quotient method, the tributaries draining wastewater effluents should be hotspots that warrant further research in future.

Hardness-dependent water quality criteria for cadmium and an ecological risk assessment of the Shaying River Basin, China

Hardness is one important water quality parameter that influences the toxicity of cadmium. Several studies have derived water quality criteria (WQC) for cadmium, but most of these studies did not consider environmental factors. Moreover, few studies considered environmental factors when carrying out ecological risk assessments (ERA) based on environmental factors. In this research, six native aquatic organisms in the Shaying River were adopted to conduct toxicity tests for cadmium. By combining published toxicity data for cadmium with hardness values and toxicity data from this study, hardness-dependent WQC were established. When normalized to a hardness of 100 mg/L CaCO₃, the criterion maximum concentration (CMC) of 6.46 μg/L and criterion continuous concentration (CCC) of 1.49 μg/L in the Shaying River Basin were derived according to the USEPA guidelines. The acute predicted no effect concentrations (PNECs) derived by species sensitivity distribution (SSD) methods based on log-logistic, log-normal and Burr Type III models were 1.03, 2.41 and 1.66 μg/L, respectively. Recommended WQC values finally expressed as a function of hardness: (1) CMC=(1.136672-0.041838 × lnH) × e^{0.9969×lnH-2.6676}; and (2) CCC=(1.101672-0.041838 × lnH) × e^{1.0083×lnH-6.1156}. In addition, three tiers of ERA of cadmium in surface waters were conducted based on hardness obtained during different seasons in the Shaying River using the hazard quotient (HQ), the margin of safety (MOS₁₀), and the joint probability (JPC) methods. In tiered 1, 2, and 3 ERA, cadmium exposure concentrations were standardized to a hardness of 100 mg/L. The three levels of the ERA method in the tiered framework gave consistent results: the ecological risks of cadmium in the Shaying River Basin were at acceptable levels. The present study provides a reference for the derivation of WQC and risk assessment of pollution affected by differences in aquatic species and water quality factors such as hardness.

Polycyclic Aromatic Hydrocarbons in Surface Water from Wuhai and Lingwu Sections of the Yellow River: Concentrations, Sources, and Ecological Risk

In this study, concentrations, sources, and ecological risk of 16 polycyclic aromatic hydrocarbons (PAHs) in 41 surface water samples collected from Wuhai and Lingwu sections of the Yellow River were investigated. The results showed that total PAH concentrations varied from 27.5 ng/L to 234 ng/L and from 135 ng/L to 265 ng/L in surface water of Wuhai and Lingwu sections, respectively. Source identification was performed by using principal component and multiple linear regression analysis. PAHs in Wuhai section of the Yellow River were mainly from coal combustion (35%) and vehicle exhausts (34%). Ecological risk of PAHs to aquatic organisms was assessed by applying the probabilistic risk assessment method. The results showed that the probabilities of exceeding the chronic toxicity for 5% of the species were 28% and 32% for PAHs in surface water from Wuhai and Lingwu sections, respectively. It has been demonstrated that there is an urgent need for environmental managers to take measures to reduce the ecological risk of PAHs in the aquatic environment in both Wuhai and Lingwu sections of the Yellow River.

Combining species sensitivity distribution (SSD) model and thermodynamic index (exergy) for system-level ecological risk assessment of contaminates in aquatic ecosystems

After reviewing the species- and community-level ecological risk assessments (ERAs) of chemicals in the aquatic environment, the present study attempted to propose a third stage of ERA, i.e., the ecosystem-level ERA. Based on the species sensitivity distribution model (SSD) and thermodynamic theory, the exergy and biomass indicators of communities from various trophic levels (TLs) were introduced to improve ecological connotation of SSDs. The species were classified into three TLs based on algae (TL1), invertebrates (TL2), and vertebrates (TL3), and the weight of each TL was determined based on relative biomass and β value, which indicated a holistic contribution of each species or community to the ecosystem. Then, a system-level ERA protocol was successfully established, and the community- and system-level ecological risks of 10 typical toxic micro-organic pollutants in the western area of Lake Chaohu and its inflowing rivers were evaluated. System-level ERA curves (ExSSD) were mainly affected by the community-level SSD at TL2 for most chemicals in the present study. The uncertain boundary of ExSSD was mostly related to TLs with a wider uncertain boundary, but had little relation to the weight of each TL. The results of system-level ERAs revealed that dibutyl phthalate had the highest eco-risk, whereas γ-hexachlorocyclohexane presented the lowest eco-risk. Results of the system-level ERA were not fully consistent with the those of community-level ERA owing to the lack of a sufficient dataset, SSD model type, and ecosystem structure, as indicated by the weight of each TL. The successful application of ExSSD in Lake Chaohu signifies the start of the third stage of ERA at the system-level, and it also provides a scientific basis for ecosystem-level ERA, aquatic ecosystem protection, and future water safety management. However, there were some limitations, including sufficient data dependence, neglect of ecological interactions, and neglect of environmental parameters such as natural organic matter. We propose to employ toxicogenomics to enrich the toxicity database, to simulate the interaction using the ecological dynamic model, and to introduce the chemical fate model into the system-level ERA.

Deriving aquatic life criteria for galaxolide (HHCB) and ecological risk assessment

The polycyclic musk galaxolide (HHCB) is widely used as fragrances in personal care products (PCPs) and has been detected in various environmental media. There is an urgent need to derive aquatic life criteria (ALC) of HHCB for the protection of aquatic organisms. Toxicity tests with 8 Chinese resident aquatic organisms from 3 phyla and 8 families were conducted, and three methods were used for deriving the ALC. A criterion maximum concentration (CMC) of 8.33 μg/L and a criterion continuous concentration (CCC) of 2.20 μg/L were derived according to the USEPA guidelines. The acute predicted no effect concentrations (PNECs) values derived by log-normal species sensitivity distribution (SSD) and log-logistic SSD method were 77.41 and 66.47 μg/L, respectively. In addition, a significant sensitivity difference was observed between the planktonic crustacean and benthic crustacean, and there was no significant difference (p > 0.05) among SSDs based on resident and non-resident species. A comparison of chronic SSDs between HHCB, tonalide (AHTN) and musk ketone (MK) showed that nitro musk (MK) was more toxic to aquatic organisms than polycyclic musks (HHCB and AHTN). Finally, an assessment of risk to aquatic organisms in surface waters and effluents of wastewater treatment plants (WWTPs) worldwide showed that potential risk may exist at several locations. HHCB concentrations in 4.08 and 46.17% of the WWTP effluents in China and 1.71 and 16.13% of the WWTP effluents in other countries exceed the hazard concentration for 5% and 1% aquatic species.

Organochlorine pesticides in the soils from Benevento provincial territory, southern Italy: Spatial distribution, air-soil exchange, and implications for environmental health

This study comprehensively interprets the contamination status of organochlorine pesticides (OCPs) in the soils from Benevento provincial territory, southern Italy, and its implications for environmental health by means of a systematic grid sampling method and geostatistics. The total concentrations of OCPs in the soils ranged from 0.058 to 16.9 ng/g, with a geometric mean (GM) of 0.72 ng/g and an arithmetic mean (AM) of 1.71 ng/g. The levels of OCPs were dominated by p,p'-DDE, p,p'-DDD, HCB, contributing together to 73.5% of the total OCPs. The higher levels of HCB, DDTs, and HCHs found in southwestern, central and east Benevento provincial territory, all occurring adjacent to landfill sites. The residues of OCPs in soil are largely ascribed to their historical use. The OCP inventories in soils of Benevento provincial territory ranged from 0.13 to 4.84 metric tons, with GM = 0.42 metric tons and AM = 0.44 metric tons. The soil is likely to be a sink for DDTs under the influence of regional air transport from pollution hotspots and has the potential to release other chemicals with a high vapor pressure, e.g., HCB, HCHs, and α-Endosulfan. And the mean level of the air-soil exchange flux of HCB, HCHs, and DDTs is estimated to be -1.59, -0.72, and 0.10 ng/m²/day respectively. The potential ecological and human health risks caused by OCPs in the soils are deemed essentially negligible in Benevento provincial territory.

Probabilistic ecological risk assessment of heavy metals in western Laizhou Bay, Shandong Province, China

Considering the serious land-based pollution and the weak water exchange ability of western Laizhou Bay, it is essential to conduct an ecological risk assessment of the pollutants in this area. In this study, the ecological risk caused by heavy metals deposited in the surface sediments and those resuspended in the seawater of western Laizhou Bay was evaluated using probabilistic approaches. First, the concentrations of seven heavy metals, namely As, Cd, Cr, Cu, Hg, Pb, and Zn, in the surface sediments and seawater of western Laizhou Bay were detected during the spring and autumn of 2016. The concentrations of As, Cd, Cr, Cu, and Pb were found to be at levels comparable to those in the other global coastal systems, while those of Hg and Zn were lower than those in other coastal areas. Next, an ecological risk assessment of heavy metals in the surface sediments was performed using a typical potential ecological risk index and refined by using a Monte Carlo simulation. The results suggested low risk for the heavy metals detected in the sediments of western Laizhou Bay, with the exception of Hg in September 2016, which showed a probability (0.03%) of moderate risk. Meanwhile, the aquatic ecological risk assessment of the heavy metals was performed by applying a combination of hazard quotient (HQ) and joint probability curve. While the ecological risk of Cd, Hg, and Pb was found to be acceptable, the HQs for Cr, Cu, and Zn were greater than 1, and the overall risk probability of their adverse effects was higher than 0.05, suggesting certain ecological risk. Specifically, in the case of As, the overall risk probability was lower than 0.05, suggesting that its ecological risk was acceptable, although its HQ was greater than 1. Thus, by applying the probabilistic approaches, the ecological risk of the heavy metals in western Laizhou Bay was better characterized in this study, avoiding both overestimation and underestimation of ecological risk.

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.

Occurrence and potential human health risks of semi-volatile organic compounds in drinking water from cities along the Chinese coastland of the Yellow Sea

Semi-volatile organic compounds (SVOCs) in drinking water have been considered a severe threat to public health worldwide. However, SVOC contamination and the associated human health risks of the drinking water from cities along tributaries of the Yangtze River and Huaihe River in China have been seldom reported. Here, we focused on the occurrence and distribution of a series of SVOCs, mainly including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and phthalate esters (PAEs), in drinking water of this region. In brief, a total of 31 SVOCs were detectable in all of the drinking water samples, and the total concentrations ranged from 0.92 ng/L to 266.16 ng/L in March and from 24.82 ng/L to 643.93 ng/L in August, with the highest concentrations in Dongtai (DT) and Xinghua (XH), respectively. Spatial and temporal differences of the SVOCs were also observed in drinking water samples, demonstrating the linkage between pollutant profiles and geographical locations, as well as exogenous wastewater discharge. Moreover, PAEs occupied 79.17-100.00% of the total concentrations of SVOCs in drinking water samples collected from the tributaries of the Yangtze River in March, while OCPs were the predominant SVOCs in most of drinking water samples from the tributaries of the Huaihe River. The human health assessment indicated that SVOCs posed negligible non-carcinogenic risks, but residents living in DT, Dafeng (DF), Chengdong (CD), Guanyun (GY) and Lianyungang (LY) may suffer carcinogenic health risks, which could be mainly induced by benzene hexachloride and heptachlor in August.

Ecological risks posed by ammonia nitrogen (AN) and un-ionized ammonia (NH3) in seven major river systems of China

Previous studies showed that continuous exposure to ammonia nitrogen (AN) contributed to regional losses of benthic invertebrate diversity in China. Yet, the overall ecological risk of AN to aquatic organisms in major riverine systems of China has not been appropriately studied. Our research then investigated temporal (seasonally/yearly) and spatial distributions of AN and un-ionized ammonia (NH₃) in major Chinese river basins using historic data generated between 2007 and 2014, and developed risk assessment criteria. Our results showed that the highest average AN concentrations occurred during winter (0.82-2.76 mg/L) and the lowest during summer (0.36-0.78 mg/L). NH₃ exhibited the opposite trend with the highest average concentrations mostly observed during spring (15.13-92.84 μg/L) and the lowest concentrations mainly during winter (10.53-45.43 μg/L). Both AN and NH₃ concentrations steadily increased and reached maximum levels in 2008 (AN: 1.22 mg/L and NH₃: 50.65 μg/L), and then decreased. Temporal trends showed that the Yellow, Hai, and Huai river basins had the highest AN and NH₃ concentrations. Subsequently, conventional (hazard quotients) and probabilistic (joint probability curves) methods were applied to assess the hazards and risks posed by AN and NH₃. The results showed that the probability of exceeding the acute toxicity threshold for 5% of species (exposed to AN or NH₃) was less than 13.3% and gradually decreased over time. To protect aquatic organisms, an acute criterion of 51.4 μg NH₃/L and a chronic criterion of 1.14 mg AN/L at pH = 7.5, 20 °C were developed and are recommended for future risk assessment studies.

Polycyclic aromatic hydrocarbons and organochlorine pesticides in surface water from the Yongding River basin, China: Seasonal distribution, source apportionment, and potential risk assessment

The presence of 17 polycyclic aromatic hydrocarbons (PAHs) and 15 persistent organochlorine pesticides (OCPs) in surface water of the Yongding River Basin was analyzed through GC/MS/MS during the spring and summer at 46 sampling sites. The goal was to investigate their seasonal distribution, possible sources, and potential risk. Our results showed that the total PAH concentration in surface water of Yongding River Basin ranged from 41.60 to 1482.60ng/L with a mean value of 137.85ng/L in the spring, and from 53.53 to 506.53ng/L with a mean value of 124.43ng/L in the summer. The total OCP concentration ranged from <0.08 to 197.71ng/L with a mean value of 7.69ng/L in the spring, and from <0.08 to 93.58ng/L with a mean value of 7.92ng/L in the summer. Moreover, the total PAH concentration was slightly lower in the spring than in the summer, whereas the total OCP concentration was similar between seasons. Source analysis indicated that combustion sources and petroleum sources both contributed to the presence of PAHs. Historical environmental residues and long range atmospheric transport were the major sources of HCH and DDT contamination. The concentrations of total PAHs and single PAHs including benz(a)anthracene, benzo(a)pyrene, benz(b)fluoranthene, and benz(k)fluoranthene in surface water at some sampling sites exceeded the water environmental quality standards of China and several other countries or organizations. This indicated a potential threat to human health from the consumption of aquatic organisms due to PAH bioaccumulation. The concentrations of α-HCH, p,p'-DDE, and p,p'-DDD at several sampling sites exceeded the limit for human health specified in the ambient water quality criteria developed by the US Environmental Protection Agency, which indicated that these pollutants provide potential hazards to the residents around the sampling sites.

Pesticide use in the wheat-maize double cropping systems of the North China Plain: Assessment, field study, and implications

In the North China Plain (NCP), rising inputs of pesticides have intensified the environmental impact of farming activities in recent decades by contributing to surface water and groundwater contamination. In response to this, the Chinese government imposed stricter regulations on pesticide approval and application, and better monitoring strategies are being developed. However, sufficient and well-directed research on the accumulation and impact of different pesticides is needed for informed decision-making. In this study, current pesticide use, and recent and current research on water contamination by pesticides in the NCP are reviewed and assessed. Additionally, a small-scale field study was performed to determine if residuals from currently-used pesticides in the NCP can be detected in surface water, and in connected shallow groundwater. The contaminants of interest were commonly used pesticides on winter wheat-summer maize fields (the dominant cropping system in the NCP), such as 2,4-D and atrazine. Sampling took place in May, July, and October 2013; and March 2014. Results from our literature research showed that sampling is biased towards surface water monitoring. Furthermore, most studies focus on organic chlorinated pesticides (OCPs) like the isomers of dichlorodiphenyltrichloroethane (DDT) and hexachlorocyclohexane (HCH), which were banned in China in 1983. However, currently-used herbicides like 2,4-D and atrazine were detected in river water and groundwater in all samplings of our field study. The highest concentrations of 2,4-D and atrazine were found in the river water, ranging up to 3.00 and 0.96μg/L, respectively. The monitoring of banned compounds was found to be important because several studies indicate that they are still accumulating in the environment and/or are still illegally in use. However, supported by our own data, we find that the monitoring in groundwater and surface water of currently permitted pesticides in China needs equal attention, and should therefore be increased.

Benthic invertebrate exposure and chronic toxicity risk analysis for cyclic volatile methylsiloxanes: Comparison of hazard quotient and probabilistic risk assessment approaches

This study utilized probabilistic risk assessment techniques to compare field sediment concentrations of the cyclic volatile methylsiloxane (cVMS) materials octamethylcyclotetrasiloxane (D4, CAS # 556-67-2), decamethylcyclopentasiloxane (D5, CAS # 541-02-6), and dodecamethylcyclohexasiloxane (D6, CAS # 540-97-6) to effect levels for these compounds determined in laboratory chronic toxicity tests with benthic organisms. The concentration data for D4/D5/D6 in sediment were individually sorted and the 95th centile concentrations determined in sediment on an organic carbon (OC) fugacity basis. These concentrations were then compared to interpolated 5th centile benthic sediment no-observed effect concentration (NOEC) fugacity levels, calculated from a distribution of chronic D4/D5/D6 toxicologic assays per OECD guidelines using a variety of standard benthic species. The benthic invertebrate fugacity biota NOEC values were then compared to field-measured invertebrate biota fugacity levels to see if risk assessment evaluations were similar on a field sediment and field biota basis. No overlap was noted for D4 and D5 95th centile sediment and biota fugacity levels and their respective 5th centile benthic organism NOEC values. For D6, there was a small level of overlap at the exposure 95th centile sediment fugacity and the 5th centile benthic organism NOEC fugacity value; the sediment fugacities indicate that a negligible risk (1%) exists for benthic species exposed to D6. In contrast, there was no indication of risk when the field invertebrate exposure 95th centile biota fugacity and the 5th centile benthic organism NOEC fugacity values were compared.

Derivation of aquatic predicted no-effect concentration (PNEC) for ibuprofen and sulfamethoxazole based on various toxicity endpoints and the associated risks

For pharmaceuticals, the ecological risk assessment based on traditional endpoints of toxicity could not be properly protective in the long run since the mode of action could vary because they are intended for different therapeutic uses. In this study, the predicted no-effect concentrations (PNECs) of two selected pharmaceuticals, ibuprofen (IBU) and sulfamethoxazole (SMX), were derived based on either traditional endpoints of survival and growth data or some nonlethal endpoints such as reproduction, biochemical and molecular data. The PNECs of IBU based on biochemical-cellular and reproduction data were 0.018 and 0.026 μg L^-1 that were significantly lower than those derived from other endpoints, while the lowest PNEC for SMX derived from growth data with the concentration of 0.89 μg L^-1. Ecological risk assessment was performed for IBU and SMX to the aquatic environment by applying hazard quotient and probabilistic distribution based quotient (DBQs) methods. The results showed that the probability of DBQs of IBU exceeding 0.1 was 11.2%, while for SMX the probability was 0.9% that could be neglected.

Toxicological and chemical insights into representative source and drinking water in eastern China

Drinking water safety is continuously threatened by the emergence of numerous toxic organic pollutants (TOPs) in environmental waters. In this study, an approach integrating in vitro bioassays and chemical analyses was performed to explore toxicological profiles of representative source and drinking water from waterworks of the Yangtze River (Yz), Taihu Lake (Th), and the Huaihe River (Hh) basins in eastern China. Overall, 34 of 96 TOPs were detected in all water samples, with higher concentrations in both source and drinking water samples of Hh, and pollutant profiles also differed across different river basins. Non-specific bioassays indicated that source water samples of Hh waterworks showed higher genotoxicity and mutagenicity than samples of Yz and Th. An EROD assay demonstrated dioxin-like toxicity which was detected in 5 of 7 source water samples, with toxin concentration levels ranging from 62.40 to 115.51 picograms TCDD equivalents per liter of water (eq./L). PAHs and PCBs were not the main contributors to observed dioxin-like toxicity in detected samples. All source water samples induced estrogenic activities of 8.00-129.00 nanograms 17β-estradiol eq./L, and estrogens, including 17α-ethinylestradiol and estriol, contributed 40.38-84.15% of the observed activities in examined samples. While drinking water treatments efficiently removed TOPs and their toxic effects, and estrogenic activity was still observed in drinking water samples of Hh. Altogether, this study indicated that the representative source water in eastern China, especially that found in Hh, may negatively affect human health, a finding that demonstrates an urgent requirement for advanced drinking water treatments.

How sulfate-rich mine drainage affected aquatic ecosystem degradation in northeastern China, and potential ecological risk

Mining activity is an increasingly important stressor for freshwater ecosystems. However, the mechanism on how sulfate-rich mine drainage affects freshwater ecosystems is largely unknown, and its potential ecological risk has not been assessed so far. During 2009-2016, water and macroinvertebrate samples from 405 sample sites were collected along the mine drainage gradient from circum-neutral to alkaline waters in Hun-Tai River, Northeastern China. Results of linear regressions showed that sulfate-rich mine drainage was significantly positively correlated with the constituents typically derived from rock weathering (Ca²⁺, Mg²⁺ and HCO₃^-+CO₃^2-); the diversity of intolerant stream macroinvertebrates exhibited a steep decline along the gradient of sulfate-rich mine drainage. Meanwhile, stressor-response relationships between sulfate-rich mine drainage and macroinvertebrate communities were explored by two complementary statistical approaches in tandem (Threshold Indicator Taxa Analysis and the field-based method developed by USEPA). Results revealed that once stream sulfate concentrations in mine drainage exceeded 35mg/L, significant decline in the abundance of intolerant macroinvertebrate taxa occurred. An assessment of ecological risk posed by sulfate-rich mine drainage was conducted based on a tiered approach consisting of simple deterministic method (Hazard Quotient, HQ) to probabilistic method (Joint Probability Curve, JPC). Results indicated that sulfate-rich mine drainage posed a potential risk, and 64.62-84.88% of surface waters in Hun-Tai River exist serious risk while 5% threshold (HC₀₅) and 1% threshold (HC₀₁) were set up to protect macroinvertebrates, respectively. This study provided us a better understanding on the impacts of sulfate-rich mine drainage on freshwater ecosystems, and it would be helpful for future catchment management to protect streams from mining activity.

Residues of hexachlorobenzene and chlorinated cyclodiene pesticides in the soils of the Campanian Plain, southern Italy

A systematic grid sampling method and geostatistics were employed to investigate the spatial distribution, inventory, and potential ecological and human health risks of the residues of hexachlorobenzene (HCB) and chlorinated cyclodiene pesticides in soils of the Campanian Plain, Italy, and explore their relationship with the soils properties. The geometric mean (Gmean) concentrations of HCB and cyclodiene compounds followed the order CHLs (heptachlor, heptachlor epoxide, trans-chlordane, and cis-chlordane) > DRINs (aldrin, dieldrin, and endrin) > SULPHs (α-endosulfan, β-endosulfan, and endosulfan sulfate) > HCB. The residual levels of most cyclodienes in agricultural soils were generally higher than those of corresponding counterparts in the other land uses. Significant differences in the concentration of HCB and cyclodienes in the soils across the region are observed, and the Acerra-Marigliano conurbation (AMC) and Sarno River Basin (SRB) areas exhibit particularly high residual concentrations. Some legacy cyclodienes in the Campanian Plain may be attributed to a secondary distribution. The Gmean inventory of HCB, SULPHs, CHLs, and DRINs in the soil is estimated to be 0.081, 0.41, 0.36, and 0.41 metric tons, respectively. The non-cancer and cancer risks of HCB and cyclodienes for exposed populations are deemed essentially negligible, however, endosulfan poses significant ecological risks to some terrestrial species.

Deriving acute and chronic predicted no effect concentrations of pharmaceuticals and personal care products based on species sensitivity distributions

Pharmaceuticals and personal care products (PPCPs), as emerging contaminants, have been detected in various environmental matrices and caused adverse effects on human health and the ecosystem. But water quality criterias (WQCs) of PPCPs for protecting aquatic environment are lacking, which hinders the environmental management of these emerging contaminants. In the present study, in order to support their WQC derivation, acute and chronic hazardous concentrations for 5% of species (HC₅s) of some frequently detected PPCPs in China were calculated based on acute and chronic species sensitivity distributions (SSDs), respectively, using both parametric (log-normal and log-logistic) and nonparametric bootstrap approaches. The groups of aquatic species used in SSDs included planktons, zooplanktons, invertebrates and vertebrates. Acute and chronic predicted no effect concentrations (PNECs) were derived from the HC₅s. The acute PNECs of the selected PPCPs were in a range from 1.1 to 4993μg/L. While the chronic PNECs were one or two orders of magnitude lower than the acute PNECs, with a range from 0.02 to 298μg/L. Among these PPCPs, the compound with the highest acute effect on the aquatic environment was clarithromycin while erythromycin was the one with the highest chronic toxicity effect. Among the studied PPCPs, erythromycin caused a relatively higher aquatic ecological risk in China. This study helps derive WQCs of PPCPs in the aquatic environment, which is essential for environmental managment of these emerging contaminants.

Derivation of predicted no-effect concentration and ecological risk for atrazine better based on reproductive fitness

Atrazine (ATZ) is an herbicide most commonly used in China and other regions of the world. It is reported toxic to aquatic organisms, and frequently occurs at relatively high concentrations. Currently, ATZ has been proved to affect reproduction of aquatic species at much lower levels. So it is controversial to perform ecological risk assessment using predicted no-effect concentrations (PENCs) derived from traditional endpoints, which fail to provide adequate protection to aquatic organisms. In this study, PNECs of ATZ were derived based on six endpoints of survival, growth, behavior, biochemistry, genetics and reproduction. The PNEC derived from reproductive lesion was 0.044μg ATZ L^-1, which was obviously lower than that derived from other endpoints. In addition, a tiered ecological risk assessment was conducted in the Taizi River based on six PNECs derived from six categories of toxicity endpoints. Results of these two methods of ecological risk assessment were consistent with each other, and the risk level of ATZ to aquatic organisms reached highest as taking reproductive fitness into account. The joint probability indicated that severe ecological risk rooting in reproduction might exist 93.9% and 99.9% of surface water in the Taizi River, while 5% threshold (HC₅) and 1% threshold (HC₁) were set up to protect aquatic organisms, respectively. We hope the present work could provide valuable information to manage and control ATZ pollution.

Levels and Sources of Organochlorine Pesticides in Surface Sediment from Anhui Reach of Huaihe River, China

Twenty-two organochlorine pesticides (OCPs) were investigated in Anhui reach of Huaihe river, China. Seventeen out of 22 OCPs were detected by GC-MS. The mean concentrations of OCPs followed the order: HCHs > DDTs > HCB > chlordanes > endosulfans. Levels of total HCHs and total DDTs ranged from 2.54 to 13.91 ng g^-1 (mean = 7.52 ng g^-1) and 0.016 to 2.54 ng g^-1 (mean = 0.45 ng g^-1), respectively. The concentrations of DDTs were lower than those of HCHs. Compared with the other rivers in China, DDTs and HCHs were relatively lower or similar. Statistical analysis indicated that the OCPs concentration differences were not insignificant between upstream, midstream and downstream. The compound compositions suggested that historical usage of lindane and fresh DDT were the main sources. The regression analysis indicated that TOC has influence on the levels of HCHs and little influence on the levels of DDTs in the sediments.

Tiered probabilistic assessment of organohalogen compounds in the Han River and Danjiangkou Reservoir, central China

Occurrence of organohalogen contaminants (OCs) including 12 organochlorine pesticides (OCPs), 7 polychlorinated biphenyl congeners (PCBs) and 7 polybrominated diphenyl ethers (PBDEs) were investigated in the Han River, which is the largest tributary of the Yangtze River, and Danjiangkou Reservoir, the source of water for China's South-to-North Water Diversion Project. OCPs were found to be dominant in water, with concentrations of 0.14-11 and 2.9-59ngL^-1during winter and summer, respectively. In sediment, OCPs were also predominant contaminants during summer (5.0-1.7×10²ngg^-1), whereas during winter PCBs (4.3-2.3×10²ngg^-1) were dominant. Concentrations of OCs observed during this study were generally less or comparable to those from other locations in the world. Concentrations of OCPs were significantly greater in lower reaches of the Han River, during winter. This observation might be due to proximity of this location to more developed areas. Distributions of OCs between water and sediment were not at steady state except for PBDEs during winter. This disequilibrium is likely due to continuing inputs of pollutants. A tiered assessment of risks to aquatic organisms was conducted for OCs. Initially species sensitivity distributions (SSD) were employed to determine predicted no effect concentration (PNEC), followed by evaluation based on hazard quotients (HQ). In subsequent tiers, a probabilistic approach was used to develop joint probability distributions, where species sensitivity distributions were compared to distributions of measured concentrations of OCs. Consistent results were obtained by use of all methods, which suggested endosulfans and heptachlors could pose risk to local aquatic organisms. Furthermore, heptachlors and PCBs might also cause potential adverse effect to health of humans through consumption of water.