Human activities induce potential aquatic threats of micropollutants in Danjiangkou Reservoir, the largest artificial freshwater lake in Asia

Reshuffling the risk values of pesticides in surface-groundwater systems: Evidence from mining intensity and hydrogeological vulnerabilities

The extensive application of pesticides in agricultural cultivation and crop maintenance has resulted in their widespread occurrence and accumulation across diverse environmental media. This study screened >52 target pesticides occurs in both surface and groundwater, including 16 carbamates, 8 triazines, 6 triazoles, 4 chloroacetanilides, 3 neonicotinoids, 3 pyrazoles, 2 morpholines, and 10 other types of pesticides within the Wulong River Basin, situated on the Shandong Peninsula in China. The target pesticides in surface water ranged from below the limit of quantification (LOQ) to 111.2 ng/L, whereas in groundwater, they ranged from below LOQ to 148.1 ng/L. 63 % (p < 0.05) of the target pesticides follow the migration rule, where the concentration in surface water appears exceeded groundwater. 37 % overcome the pesticide properties and aquifer intrinsic vulnerability and show higher values in groundwater. The risk quotient values for imidacloprid and atrazine exceeded 1 at 86 % of the sampling sites, indicating a high level of chronic ecological risk to aquatic organisms. The assessment of pesticide mixtures posed 15 % to 24 % higher risk levels to aquatic organisms compared to individual pesticides. While the non-carcinogenic risks associated with groundwater across all age groups were below the threshold of 1, there was a significant potential carcinogenic risk, particularly for children, warrants due attention. This study provides a new perspective for the systematic analysis of surface-groundwater systems and identify the exposure potential of pesticides in different water bodies and generate priority levels for risk assessment.

Characteristics, sources, and concentration prediction of endocrine disruptors in a large reservoir driven by hydrological rhythms: A case study of the Danjiangkou Reservoir

Herein, we present the first systematic investigation to clarify the effect of hydrological rhythms on the concentrations and distributions of polycyclic aromatic hydrocarbons (PAHs) and phthalate esters (PAEs) in the Danjiangkou Reservoir. The results revealed that hydrological rhythms remarkably affected the PAH and PAE concentrations and distributions in the water body, wherein the PAH concentration peaked in the flood season while the PAE concentration remarkably increased in the dry season. This study represents methodological innovation, revealing significant heterogeneity of PAHs and PAEs across different water layers. The former compounds tended to accumulate in the water body's bottom layer while the latter compounds had the highest concentration at the surface layer, which can be attributed to the different physicochemical properties and environmental transport behaviors of the two compound types. The overall concentrations of PAHs and PAEs fall within the international and domestic safety standards. The primary sources of these contaminants-coal and biomass combustion for PAHs and widespread use of plastic products for PAEs-are critical areas of regulatory focus. A machine learning model is proposed for the first time for predicting PAE concentrations in the Danjiangkou Reservoir, primarily based on the stacking model and supplemented by the random forest or XGBoost models.

Comprehensive monitoring and prioritizing for contaminants of emerging concern in the Upper Yangtze River, China: An integrated approach

Contaminants of emerging concern (CECs) in aquatic environments can adversely impact ecosystems and human health even at low concentrations. This study assessed the risk of 162 CECs, including neonicotinoid pesticides, triazine pesticides, carbamate pesticides, psychoactive substances, organophosphate esters, antidepressants, per- and polyfluoroalkyl substances, and antibiotics in 10 drinking water sources and two tributaries (Jialing and Wujiang Rivers) of the Upper Yangtze River in Chongqing, China. Target screening detected 156 CECs at 0.01-2218.2 ng/L, while suspect screening via LC-QTOF-MS identified 64 CECs, with 13 pesticides, 29 pharmaceuticals and personal care products, and 2 industrial chemicals reported for the first time in the Yangtze River Basin. Risk quotient-based ecological risk assessment revealed that 48 CECs posed medium to high risks (RQ > 0.1) to aquatic life, with antibiotics (n = 20) as the main contributors. Non-carcinogenic risks were below negligible levels, but carcinogenic risks from neonicotinoids, triazines, antidepressants, and antibiotics were concerning. A multi-criteria prioritization approach integrating occurrence, physico-chemical properties, and toxicological data ranked 26 CECs as high priority. This study underscores the importance of comprehensive CEC screening in rivers and provides insights for future monitoring and management strategies.

Which pollutants and sources should be prioritized for control in multi-pollutants complex contaminated areas?

Risk assessment and source identification of multi-pollutants are essential for accurate control of soil contamination. However, complexity in pollutant properties and diversity in source types raise challenges to the target. Therefore, this study constructed a hierarchical ecological risk quantification method combined with risk ranking, risk of single pollutant using potential affected fraction (PAF), and joint risk of multi-pollutants employing msPAF. Taking regional contamination in South China as a case, the risk ranking was determined, while single and joint effects showed msPAF reaching 79.4 %, with risk as heavy metals (HMs) > per- and polyfluoroalkyl substances (PFASs) > polycyclic aromatic hydrocarbons (PAHs). Meanwhile, an integrated source apportionment method was established from three layers by principal component analysis to classify source types, multiple linear regression of distance to identify key sources, and positive matrix factorization to track omitted sources. Consequently, key sources were captured, with 80.8 %-93.2 % contribution of farmland and electroplating to three main HMs, 52.2 %-69.4 % contribution of roads to three main PAHs, and 71.1 %-73.2 % contribution of electroplating to two main PFASs. Further, omitted sources were tracked with contribution of 31.2 %-84.1 % to eight pollutants. The established methods can identify control targets, including high-risk pollutants and their key sources.

Spatiotemporal variations and priority ranking of emerging contaminants in nanwan reservoir: A case study from the agricultural region in huaihe river basin in China

The presence of emerging contaminants (ECs) in drinking water sources is an increasing concern, yet limited data exists on their occurrence and risk in the upper Huaihe River Basin, an important agricultural region in Central China. This study investigated 70 ECs, including pesticide and antibiotics in surface water from drinking water source areas in Nanwan Reservoir along the upper reaches of the Huaihe River Basin to prioritize the ECs based on ecological risk and health risk assessment. A total of 66 ECs were detected in the surface water at least once at the selected 38 sampling sites, with concentrations ranging from 0.04 to 2508 ng/L. Ecological risk assessment using the risk quotient (RQ) method revealed high risks (RQ > 1) from 7 ECs in the dry season and 15 ECs in the wet season, with triazine pesticides as the main contributors. Non-carcinogenic risks were below negligible levels, but carcinogenic risks from neonicotinoid and carbamate pesticides and macrolide antibiotics were concerning for teenagers. Ciprofloxacin exhibited a high level of resistance risk during the wet season. A multi-indicator prioritization approach integrating occurrence, risk, and chemical property data ranked 6 pesticides and 3 antibiotics as priority pollutants. The results highlight EC contamination of drinking water sources in this agriculturally-intensive region and the need for targeted monitoring and management to protect water quality.

Water temperature governs organophosphate ester dynamics in the aquatic food chain of Poyang Lake

Organophosphate esters (OPEs) are increasingly recognized as pervasive environmental contaminants, primarily from their extensive application in flame retardants and plasticizers. Despite their widespread presence, the intricacies of OPE bioaccumulation within aquatic ecosystems remain poorly understood, particularly the environmental determinants influencing their distribution and the bioaccumulation dynamics across aquatic food chains. Here we show that water temperature plays a crucial role in modulating the dispersion of OPE in the aquatic environment of Poyang Lake. We quantified OPE concentrations across various matrices, uncovering levels ranging from 0.198 to 912.622 ng L-1 in water, 0.013-493.36 ng per g dry weight (dw) in sediment, 0.026-41.92 ng per g wet weight (ww) in plankton, 0.13-2100.72 ng per g dw in benthic invertebrates, and 0.31-3956.49 ng per g dw in wild fish, highlighting a pronounced bioaccumulation gradient. Notably, the intestines emerged as the principal site for OPE absorption, displaying the highest concentrations among the seven tissues examined. Among the various OPEs, tris(chloroethyl) phosphate was distinguished by its significant bioaccumulation potential within the aquatic food web, suggesting a need for heightened scrutiny. The propensity for OPE accumulation was markedly higher in benthic invertebrates than wild fish, indicating a differential vulnerability within aquatic biota. This study lays a foundational basis for the risk assessment of OPEs as emerging contaminants and underscores the imperative to prioritize the examination of bioaccumulation effects, particularly in benthic invertebrates, to inform future environmental safeguarding strategies.

Neonicotinoids as emerging contaminants in China's environment: a review of current data

Neonicotinoids (NEOs), the most widely used class of insecticides, are pervasive in the environment, eliciting concerns due to their hydrophilicity, persistence, and potential ecological risks. As the leading pesticide consumer, China shows significant regional disparities in NEO contamination. This review explores NEO distribution, sources, and toxic risks across China. The primary NEO pollutants identified in environmental samples include imidacloprid, thiamethoxam, and acetamiprid. In the north, corn cultivation represents the principal source of NEOs during wet seasons, while rice dominates in the south year-round. The high concentration levels of NEOs have been detected in the aquatic environment in the southern regions (130.25 ng/L), the urban river Sects. (157.66 ng/L), and the downstream sections of the Yangtze River (58.9 ng/L), indicating that climate conditions and urban pollution emissions are important drivers of water pollution. Neonicotinoids were detected at higher levels in agricultural soils compared to other soil types, with southern agricultural areas showing higher concentrations (average 27.21 ng/g) than northern regions (average 12.77 ng/g). Atmospheric NEO levels were lower, with the highest concentration at 1560 pg/m3. The levels of total neonicotinoid pesticides in aquatic environments across China predominantly exceed the chronic toxicity ecological threshold of 35 ng/L, particularly in the regions of Beijing and the Qilu Lake Basin, where they likely exceed the acute toxicity ecological threshold of 200 ng/L. In the future, efforts should focus on neonicotinoid distribution in agriculturally developed regions of Southwest China, while also emphasizing their usage in urban greening and household settings.

Neonicotinoid insecticides in well-developed agricultural cultivation areas: Seawater occurrence, spatial-seasonal variability and ecological risks

Neonicotinoids (NEOs) are widely used insecticides and have been detected in aquatic environments globally. However, little is known about NEOs contamination in the coastal environments under the terrestrial pressure of multiple planting types simultaneously. This study investigated the occurrence, spatial-seasonal variability, and ecological risks of NEOs along the coast of the Shandong Peninsula during the dry and wet seasons, where located many largest fruit, vegetable, and grain production bases in China. The concentrations of ∑NEOs in seawater were higher in wet seasons (surface: 195.46 ng/L; bottom: 14.56 ng/L) than in dry seasons (surface: 10.07 ng/L; bottom: 8.45 ng/L). During the wet seasons, NEOs peaked in the northern and eastern areas of the Shandong Peninsula, where the inland fruit planting area is located. While dry seasons had higher concentrations in Laizhou Bay, influenced by rivers from vegetable-growing areas. Grain crops, fruit, and cotton planting were major NEOs sources during wet seasons, while wheat and vegetables dominated in dry seasons. Moderate or above ecological risks appeared at 53.8% of the monitoring sites. Generally, NEOs caused high risks in the wet seasons mainly caused by Imidacloprid, and medium risk in the dry seasons caused by Clothianidin, which should be prevented and controlled in advance.

Ecological implications and drivers of emerging contaminants in Dongting Lake of Yangtze River Basin, China: A multi-substance risk analysis

Emerging contaminants (ECs) are increasingly recognized as a global threat to biodiversity and ecosystem health. However, the cumulative risks posed by ECs to aquatic organisms and ecosystems, as well as the influence of anthropogenic activities and natural factors on these risks, remain poorly understood. This study assessed the mixed risks of ECs in Dongting Lake, a Ramsar Convention-classified Typically Changing Wetland, to elucidate the major EC classes, key risk drivers, and magnitude of anthropogenic and natural impacts. Results revealed that ECs pose non-negligible acute (30% probability) and chronic (70% probability) mixed risks to aquatic organisms in the freshwater lake ecosystem, with imidacloprid identified as the primary pollutant stressor. Redundancy analysis (RDA) and structural equation modeling (SEM) indicated that cropland and precipitation were major drivers of EC contamination levels and ecological risk. Cropland was positively associated with EC concentrations, while precipitation exhibited a dilution effect. These findings provide critical insights into the ecological risk status and key risk drivers in a typical freshwater lake ecosystem, offering data-driven support for the control and management of ECs in China.

Concentration levels and ecological risk assessment of typical organophosphate esters in representative surface waters of a megacity

Organophosphate esters (OPEs) have been widely used as flame retardants and plasticizers in consumer and industrial products. They have been found to have numerous exposure hazards. Recently, several OPEs have been detected in surface waters around the world, which may pose potential ecological risks to freshwater organisms. In this study, the concentration, spatial variation, and ecological risk of 15 OPEs in the Beiyun and Yongding rivers were unprecedentedly investigated by the ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and risk quotient (RQ) method. The result showed that triethyl phosphate (TEP), tri (2-chloroisopropyl) phosphate (TCPP) were the most abundant OPEs with average concentrations of 55.53 ng/L and 42.29 ng/L, respectively. The concentrations of OPEs in the Beiyun River are higher than in the Yongding River, and their levels were higher in densely populated and industrial areas. The risk assessment showed that there was insignificant from OPEs to freshwater organisms in these rivers (RQs <0.1). The risk was higher downstream than upstream, which was related to human-intensive industrial activities downstream in the Yongding River. The ecological risk of OPEs in surface waters worldwide was estimated by joint probability curves (JPCs), and the result showed that there was a moderate risk for tri (2-chloroethyl) phosphate (TCEP), a low risk for trimethyl phosphate (TMP), and insignificant for other OPEs. In addition, the QSAR-ICE-SSD model was used to calculate the hazardous concentration for 5% (HC5). This result validated the feasibility and accuracy of this model in predicting acute data of OPEs and reducing biological experiments on the toxicity of OPEs. These results revealed the ecological risk of OPEs and provided the scientific basis for environmental managers.

Influence of watershed characteristics and human activities on the occurrence of organophosphate esters related to dissolved organic matter in estuarine surface water

Organophosphate esters (OPEs) are widespread in aquatic environments and pose potential threats to ecosystem and human health. Here, we profiled OPEs in surface water samples of heavily urbanized estuaries in eastern China and investigated the influence of watershed characteristics and human activities on the spatial distribution of OPEs related to dissolved organic matter (DOM). The total OPE concentration ranged from 22.3 to 1201 ng/L, with a mean of 162.6 ± 179.8 ng/L. Chlorinated OPEs were the predominant contaminant group, accounting for 27.4-99.6 % of the total OPE concentration. Tris(2-chloroisopropyl) phosphate, tris(1,3-dichloro-2-propyl) phosphate, and tributyl phosphate were the dominant compounds, with mean concentrations of 111.2 ± 176.0 ng/L, 22.6 ± 21.5 ng/L, and 14.8 ± 14.9 ng/L, respectively. Variable OPE levels were observed in various functional areas, with significantly higher concentrations in industrial areas than in other areas. Potential source analysis revealed that sewage treatment plant effluents and industrial activities were the primary OPE sources. The total OPE concentrations were negatively correlated to the mean slope, plan curvature, and elevation, indicating that watershed characteristics play a role in the occurrence of OPEs. Individual OPEs (triisobutyl phosphate, tris(2-butoxyethyl) phosphate, tris(2-chloroethyl) phosphate, and tricresyl phosphate) and Σalkyl-OPEs were positively correlated to the night light index or population density, suggesting a significant contribution of human activity to OPE pollution. The co-occurrence of OPEs and DOM was also observed, and the fluorescence indices of DOM were found to be possible indicators for tracing OPEs. These findings can elucidate the potential OPE dynamics in response to DOM in urbanized estuarine water environments with intensive human activities.

Ecological risk assessment for typical organophosphorus pesticides in surface water of China based on a species sensitivity distribution model

The ecological risks posed by widespread organophosphorus pesticide (OPs) pollution in the surface waters of China remain unclear. In this study, species sensitivity distribution (SSD) parametric statistical approaches were coupled with fully acute and chronic toxicity data to fit the sensitivity distributions of different aquatic species to five typical OPs: dimethoate, malathion, parathion-methyl, trichlorfon, and dichlorvos. Crustaceans exhibit the highest sensitivity to OPs, whereas algae are the least sensitive. The acute hazardous concentrations that affected 5 % of the species (HC5) were 0.112, 0.001, 0.001, 0.001, and 0.001 mg/L for dimethoate, malathion, parathion-methyl, trichlorfon, and dichlorvos, respectively, whereas their chronic HC5 values were 0.004, 0.004, 0.053, 0.001, and 0.0005 mg/L, respectively. Hence, dichlorvos is highly toxic and poses greater risk to non-target aquatic species. The evaluation data revealed varying geographical distribution characteristics of the ecological risks from OPs in 15 freshwater aquatic systems across different regions of China. Dichlorvos posed the highest risk in the basins of Zhejiang and Guangdong Provinces, with the highest chronic Risk Quotient (RQ) and Hazard Index (HI) at 9.34 and 9.92, respectively. This is much higher than what was collected and evaluated for foreign rivers (the highest chronic RQ and HI in foreign rivers were 1.65 and 2.24, respectively). Thus, dichlorvos in the surface waters of China poses a substantial ecological risk to aquatic organisms, and may endanger human health.

Micropollutants but high risks: Human multiple stressors increase risks of freshwater ecosystems at the megacity-scale

Micropollutants in water environments have attracted widespread attention, but how human and natural stressors influence the risks of micropollutants has not been comprehensively revealed. A megacity-scale study of the ecological risks of micropollutants in the surface water of Beijing, China is presented to illustrate the magnitudes of the influences of multiple anthropogenic and natural stressors. A total of 133 micropollutants representing typical land use patterns in Beijing, were quantified with the mean concentration range of ND (not detected) to 272 ng·L-1. The micropollutant concentrations in the south were obviously higher than those detected in the northern areas, and neonicotinoid pesticides showed the highest mean concentration of 311 ng·L-1. The chronic and acute risks of micropollutants to algae, invertebrates, and fishes were determined, and herbicides, organophosphorus esters, and insecticides account for the primary risks to algae, invertebrates, and fishes, respectively. The cropland and impervious cover cause the differences in the pollution and risks of micropollutants. The land use in riparian zones greater than 2 km shows a great influence on the chronic chemical risks (CCRs) for the three groups of species, indicating that too local scale does not explain the local pollution status. Climate conditions and human land use are important drivers explaining the CCRs to which various trophic levels of species are exposed. Results demonstrate that multiple categories of micropollutants pose adverse risks to freshwater in the megacity of Beijing, while climate conditions, pollution discharge, and human land use induce the chemical risk of micropollutants to aquatic organisms, and the land use in different riparian zones show different effects on the risks.

Ranking the risks of eighty pharmaceuticals in surface water of a megacity: A multilevel optimization strategy

Pharmaceuticals in freshwater posed ecological risks to aquatic ecosystem, however, most risk assessments of pharmaceuticals were conducted at screening level, which were limited by the availability of the toxicity data. In this study, risks of 80 pharmaceuticals including 35 antibiotics, 13 antiviral drugs, 13 illicit drugs, and 19 antidepressants in surface water of Beijing were assessed with a proposed multilevel environmental risk optimization strategy. Target pharmaceuticals were detected in surface water samples with the detection frequency from 1.7 % to 100 % and the total concentrations from 31.1 ng/L to 2708 ng/L. Antiviral drugs were the dominant pharmaceuticals. Preliminary screening-level risk assessment indicated that 20 pharmaceuticals posed low to high risks with risk quotient from 0.14 (chloroquine diphosphate) to 27.8 (clarithromycin). Thirteen pharmaceuticals were recognized with low to high risks by an optimized risk assessment method. Of them, the refined probabilistic risk assessment of joint probability curves coupling with a quantitative structure activity relationship-interspecies correlation estimation (QSAR-ICE) model was applied. Clarithromycin, erythromycin and ofloxacin were identified to pose low risks with maximum risk products (RP) of 1.23 %, 0.41 % and 0.35 %, respectively, while 10 pharmaceuticals posed de minimis risks. Structural equation modeling disclosed that human land use and climate conditions influenced the risks of pharmaceuticals by indirectly influencing the concentrations of pharmaceuticals. The results indicated that the multilevel strategy coupling with QSAR-ICE model was appropriate and effective for screening priority pollutants, and the strategy can be used to prioritize pharmaceuticals and other emerging contaminants in the aquatic environment.

Antiviral drugs in wastewater are on the rise as emerging contaminants: A comprehensive review of spatiotemporal characteristics, removal technologies and environmental risks

Antiviral drugs (ATVs) are widely used to treat illnesses caused by viruses. Particularly, ATVs were consumed in such large quantities during the pandemic that high concentrations were detected in wastewater and aquatic environment. Since ATVs are not fully absorbed by the human or animal body, this results in large amounts of them being discharged into the sewage through urine or feces. Most ATVs can be degraded by microbes at wastewater treatment plants (WWTPs), while some ATVs either require deep treatment to reduce concentration and toxicity. Parent and metabolites residing in effluent posed a varying degree of risk when entering the aquatic environment, while increasing the potential of natural reservoirs for environmentally acquired antiviral drug resistance potential. There is a rising research on the behavior of ATVs in the environment has surged since the pandemic. In the context of multiple viral diseases worldwide, especially during the current COVID-19 pandemic, a comprehensive assessment of the occurrence, removal, and risk of ATVs is urgently needed. This review aims to discuss the fate of ATVs in WWTPs from various regions in the world with wastewater as the main analyzing object. The ultimate goal is to focus on ATVs with high ecological impact and regulate their use or develop advanced treatment technologies to mitigate the risk to the environment.

Comprehensive investigation and risk assessment of organic contaminants in Yellow River Estuary using suspect and nontarget screening strategies

Contaminants of emerging concerns (CECs) include numerous chemicals that may pose known and unknown risks to the ecosystem, and identification and risk ranking of these compounds is essential for the environmental management. In this study, liquid and gas chromatography time-of-flight mass spectrometry (LC-QTOF-MS and GC-QTOF-MS) were used to characterize the occurrence of CECs in the surface water of the Yellow River Estuary (YRE). A total of 295 and 315 chemicals were identified by LC-QTOF-MS and GC-QTOF-MS, respectively. The occurrence of two compounds, erucamide and 2-phenylquinoline, was for the first time reported in the aquatic environment in YRE. The concentrations of 121 CECs, including 35 antibiotics, 49 pesticides and veterinary, 16 polycyclic aromatic hydrocarbons and 21 phthalic acid esters were further quantified by target analysis, which showed the detection of 99 compounds in the surface water in the range of 7.07-4611.26 ng/L. Ecological risks of pollutants based on the risk quotient (RQ) method revealed that 13 pollutants posed ecological risks to the aquatic ecosystem (RQ > 1), and pesticides (n = 12) were the main risk contributors. Here, all CECs data sets were finally transformed and ranked in the framework of the toxicological priority index (ToxPi), and a total of 81 priority control pollutants were identified in the surface water of YRE. This study highlighted the necessity of suspect and nontarget screening for CECs in estuaries, and revealed the importance of localized contamination sources in urban and agricultural environment.