Computational material flow analysis for thousands of chemicals of emerging concern in European waters

Development and testing of an efficient micropollutant monitoring strategy across a large watershed

In recent decades, extensive monitoring programmes have been conducted at the national, international, and project levels with the objective of expanding our understanding of the contamination of surface waters with micropollutants, which are often referred to as hazardous substances (HS). It has been demonstrated that HS enter surface waters via a number of pathways, including groundwater, atmospheric deposition, soil erosion, and urban systems. Given the ever-growing list of substances and the high resource demand associated with laboratory analysis, it is common practice to quantify the listed pathways based on emission factors derived from temporally and spatially constrained monitoring programmes. The derivation calculations are subject to high uncertainties, and substantial knowledge gaps remain regarding the relative importance of the unique pathways, territories, and periods. This publication presents a monitoring method designed to quantify the unique emission pathways of HS in large geographical areas characterized by differences in land use, population, and economic development. The method will be tested for a wide range of HS (ubiquitous organic and inorganic pollutants, pesticides, pharmaceuticals) throughout small sub-catchments located on tributaries. The results of the test application demonstrate a high diversity of both emission loads and instream concentrations throughout different regions for numerous substances. Riverine concentrations are found to be highly dependent on the flow status. Soil concentration levels of polycyclic aromatic hydrocarbons (PAH) and perfluoroalkyl substances (PFAS) are found to be in proportion, whereas that of potentially toxic elements (PTE) in a reverse relationship with economic development. In many instances, concentration levels are also contingent upon land use. The findings of this study reinforce the necessity for the implementation of harmonised and concerted HS monitoring programmes, which should encompass a diverse range of substances, emission sources, pathways and geographical areas. This is essential for the reliable development of emission factors.

Cross-scale and integrative prioritization of multi-functionality in large river floodplains

Floodplains provide an extraordinary quantity and quality of ecosystem services (ES) but are among the most threatened ecosystems worldwide. The uses and transformations of floodplains differ widely within and between regions. In recent decades, the diverse pressures and requirements for flood protection, drinking water resource protection, biodiversity, and adaptation to climate change have shown that multi-functional floodplain management is necessary. Such an integrative approach has been hampered by the various interests of different sectors of society, as represented by multiple stakeholders and legal principles. We present an innovative framework for integrated floodplain management building up on ES multi-functionality and stakeholder involvement, forming a scientifically based decision-support to prioritize adaptive management measures responding at the basin and local scales. To demonstrate its potential and limitations, we applied this cross-scaled approach in the world's most international and culturally diverse basin, the Danube River Basin in Europe. We conducted large-scale evaluations of anthropogenic pressures and ES capacities on the one hand and participatory modelling of the local socio-ecohydrological systems on the other hand. Based on our assessments of 14 ES and 8 pressures, we recommend conservation measures along the lower and middle Danube, restoration measures along the upper-middle Danube and Sava, and mitigation measures in wide parts of the Yantra, Tisza and upper Danube rivers. In three case study areas across the basin, stakeholder perceptions were generally in line with the large-scale evaluations on ES and pressures. The positive outcomes of jointly modelled local measures and large-scale synergistic ES relationships suggest that multi-functionality can be enhanced across scales. Trade-offs were mainly present with terrestrial provisioning ES at the basin scale and locally with recreational activities. Utilizing the commonalities between top-down prioritizations and bottom-up participatory approaches and learning from their discrepancies could make ecosystem-based management more effective and inclusive.

River ecological status is shaped by agricultural land use intensity across Europe

Agriculture impacts the ecological status of freshwaters through multiple pressures such as diffuse pollution, water abstraction, and hydromorphological alteration, strongly impairing riverine biodiversity. The agricultural effects, however, likely differ between agricultural types and practices. In Europe, agricultural types show distinct spatial patterns related to intensity, biophysical conditions, and socioeconomic history, which have been operationalised by various landscape typologies. Our study aimed at analysing whether incorporating agricultural intensity enhances the correlation between agricultural land use and the ecological status. For this, we aggregated the continent's agricultural activities into 20 Areas of Farming-induced Freshwater Pressures (AFFP), specifying individual pressure profiles regarding nutrient enrichment, pesticides, water abstraction, and agricultural land use in the riparian zone to establish an agricultural intensity index and related this intensity index to the river ecological status. Using the agricultural intensity index, nearly doubled the correlative strength between agriculture and the ecological status of rivers as compared to the share of agriculture in the sub-catchment (based on the analysis of more than 50,000 sub-catchment units). Strongest agricultural pressures were found for high intensity cropland in the Mediterranean and Temperate regions, while extensive grassland, fallow farmland and livestock farming in the Northern and Highland regions, as well as low intensity mosaic farming, featured lowest pressures. The results provide advice for pan-European management of freshwater ecosystems and highlight the urgent need for more sustainable agriculture. Consequently, they can also be used as a basis for European Union-wide and global policies to halt biodiversity decline, such as the post-2027 renewal of the Common Agricultural Policy.

Assessing city-wide pharmaceutical emissions to wastewater via modelling and passive sampling

With increasing numbers of chemicals used in modern society, assessing human and environmental exposure to them is becoming increasingly difficult. Recent advances in wastewater-based epidemiology enable valuable insights into public exposure to data-poor compounds. However, measuring all >26,000 chemicals registered under REACH is not just technically unfeasible but would also be incredibly expensive. In this paper, we argue that estimating emissions of chemicals based on usage data could offer a more comprehensive, systematic and efficient approach than repeated monitoring. Emissions of 29 active pharmaceutical ingredients (APIs) to wastewater were estimated for a medium-sized city in the Netherlands. Usage data was collected both on national and local scale and included prescription data, usage in health-care institutions and over-the-counter sales. Different routes of administration were considered as well as the excretion and subsequent in-sewer back-transformation of conjugates into respective parent compounds. Results suggest model-based emission estimation on a city-level is feasible and in good agreement with wastewater measurements obtained via passive sampling. Results highlight the need to include excretion fractions in the conceptual framework of emission estimation but suggest that the choice of an appropriate excretion fraction has a substantial impact on the resulting model performance.

Prioritisation of data-poor pharmaceuticals for empirical testing and environmental risk assessment

There are more than 3,500 active pharmaceutical ingredients (APIs) on the global market for human and veterinary use. Residues of these APIs eventually reach the aquatic environment. Although an environmental risk assessment (ERA) for marketing authorization applications of medicinal products is mandatory in the European Union since 2006, an ERA is lacking for most medicines approved prior to 2006 (legacy APIs). Since it is unfeasible to perform extensive ERA tests for all these legacy APIs, there is a need for prioritization of testing based on the limited data available. Prioritized APIs can then be further investigated to estimate their environmental risk in more detail. In this study, we prioritized more than 1,000 APIs used in Europe based on their predicted risk for aquatic freshwater ecosystems. We determined their risk by combining an exposure estimate (Measured or Predicted Environmental Concentration; MEC or PEC, respectively) with a Predicted No Effect Concentration (PNEC). We developed several procedures to combine the limited empirical data available with in silico data, resulting in multiple API rankings varying in data needs and level of conservativeness. In comparing empirical with in silico data, our analysis confirmed that the PEC estimated with the default parameters used by the European Medicines Agency often - but not always - represents a worst-case scenario. Comparing the ecotoxicological data for the three main taxonomic groups, we found that fish represents the most sensitive species group for most of the APIs in our list. We furthermore show that the use of in silico tools can result in a substantial underestimation of the ecotoxicity of APIs. After combining the different exposure and effect estimates into four risk rankings, the top-ranking APIs were further screened for availability of ecotoxicity data in data repositories. This ultimately resulted in the prioritization of 15 APIs for further ecotoxicological testing and/or exposure assessment.

Chemical Mixtures and Multiple Stressors: Same but Different?

Ecosystems are strongly influenced by multiple anthropogenic stressors, including a wide range of chemicals and their mixtures. Studies on the effects of multiple stressors have largely focussed on nonchemical stressors, whereas studies on chemical mixtures have largely ignored other stressors. However, both research areas face similar challenges and require similar tools and methods to predict the joint effects of chemicals or nonchemical stressors, and frameworks to integrate multiple chemical and nonchemical stressors are missing. We provide an overview of the research paradigms, tools, and methods commonly used in multiple stressor and chemical mixture research and discuss potential domains of cross-fertilization and joint challenges. First, we compare the general paradigms of ecotoxicology and (applied) ecology to explain the historical divide. Subsequently, we compare methods and approaches for the identification of interactions, stressor characterization, and designing experiments. We suggest that both multiple stressor and chemical mixture research are too focused on interactions and would benefit from integration regarding null model selection. Stressor characterization is typically more costly for chemical mixtures. While for chemical mixtures comprehensive classification systems at suborganismal level have been developed, recent classification systems for multiple stressors account for environmental context. Both research areas suffer from rather simplified experimental designs that focus on only a limited number of stressors, chemicals, and treatments. We discuss concepts that can guide more realistic designs capturing spatiotemporal stressor dynamics. We suggest that process-based and data-driven models are particularly promising to tackle the challenge of prediction of effects of chemical mixtures and nonchemical stressors on (meta-)communities and (meta-)food webs. We propose a framework to integrate the assessment of effects for multiple stressors and chemical mixtures. Environ Toxicol Chem 2023;42:1915-1936. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Tracking end-of-life stage of chemicals: A scalable data-centric and chemical-centric approach

Chemical flow analysis (CFA) can be used for collecting life-cycle inventory (LCI), estimating environmental releases, and identifying potential exposure scenarios for chemicals of concern at the end-of-life (EoL) stage. Nonetheless, the demand for comprehensive data and the epistemic uncertainties about the pathway taken by the chemical flows make CFA, LCI, and exposure assessment time-consuming and challenging tasks. Due to the continuous growth of computer power and the appearance of more robust algorithms, data-driven modelling represents an attractive tool for streamlining these tasks. However, a data ingestion pipeline is required for the deployment of serving data-driven models in the real world. Hence, this work moves forward by contributing a chemical-centric and data-centric approach to extract, transform, and load comprehensive data for CFA at the EoL, integrating cross-year and country data and its provenance as part of the data lifecycle. The framework is scalable and adaptable to production-level machine learning operations. The framework can supply data at an annual rate, making it possible to deal with changes in the statistical distributions of model predictors like transferred amount and target variables (e.g., EoL activity identification) to avoid potential data-driven model performance decay over time. For instance, it can detect that recycling transfers of 643 chemicals over the reporting years (1988 to 2020) are 29.87%, 17.79%, and 20.56% for Canada, Australia, and the U.S. Finally, the developed approach enables research advancements on data-driven modelling to easily connect with other data sources for economic information on industry sectors, the economic value of chemicals, and the environmental regulatory implications that may affect the occurrence of an EoL transfer class or activity like recycling of a chemical over years and countries. Finally, stakeholders gain more context about environmental regulation stringency and economic affairs that could affect environmental decision-making and EoL chemical exposure predictions.

European-wide spatial analysis of sewage treatment plants and the possible benefits to nature of advanced treatment to reduce pharmaceutical emissions

Pharmaceuticals are known to widely occur in the environment and to affect the health of ecosystems. Sewage treatment plants (STPs) are main emission pathways for pharmaceuticals, which are often not sufficiently removed during wastewater treatment. In Europe, STP treatment requirements are specified under the Urban WasteWater Treatment Directive (UWWTD). The introduction of advanced treatment techniques, such as ozonation and activated carbon, under the UWWTD is expected to be an important option to reduce pharmaceutical emissions. In this study, we present a European-wide analysis of STPs reported under the UWWTD, their current treatment level and potential to remove a set of 58 prioritised pharmaceuticals. Three different scenarios were analysed to show 1) UWWTD present effectiveness, 2) the effectiveness at full UWWTD compliance, and 3) the effectiveness when advanced treatment is implemented at STPs with a treatment capacity of >100.000 person equivalents. Based on a literature study, the potential of individual STPs to reduce pharmaceutical emissions ranged from an average of 9% for STPs with primary treatment to 84% for STPs applying advanced treatment. Results of our calculations show that European-wide emission of pharmaceuticals can be reduced with 68% when large STPs are updated with advanced treatment, but spatial differences exist. We argue that adequate attention should also be paid with regards to preventing environmental impacts of STPs with a capacity <100.000 p.e. Circa 44% of total STP effluent is emitted near Natura2000 sites (EU nature protection areas). Of all surface waters receiving STP effluent for which the ecological status has been assessed under the Water Framework Directive, 77% have a status of less than good. Relatively often only primary treatment is applied to wastewater emitted into coastal waters. This analysis can be used to further model pharmaceutical concentrations in European surface waters, to identify STPs for which more advanced treatment might be required and to protect EU aquatic biodiversity.

Risk assessment of chemicals and their mixtures are hindered by scarcity and inconsistencies between different environmental exposure limits

In chemical risk assessment, measured or modelled environmental concentrations are compared to environmental exposure limits (EELs), such as Predicted No Effect Concentrations (PNECs) or hazardous concentrations for 5% of species (HC05s) derived from species sensitivity distributions (SSDs). However, for many chemicals the EELs include large uncertainties or, in the worst case, the necessary data for their estimation are completely missing. This makes the assessment of chemical risks and any subsequent implementation of management strategies challenging. In this study we analyzed the uncertainty of EELs and its impact on chemical risk assessment. First, we compared three individual EEL datasets, two primarily based on experimental data and one based on computational predictions. The comparison demonstrates large disagreements between EEL data sources, with experimentally derived EELs differing by more than seven orders of magnitude. In a case-study, based on the predicted emissions of 2005 chemicals, we showed that these uncertainties lead to significantly different risk assessment outcomes, including large differences in the magnitude of the total risk, risk driver identification, and the ranking of use categories as risk contributors. We also show that the large data-gaps in EEL datasets cannot be covered by commonly used computational approaches (QSARs). We conclude that an expanded framework for interpreting risk characterization outcomes is needed. We also argue that the large data-gaps present in ecotoxicological data need to be addressed in order to achieve the European zero pollution vision as the growing emphasis on ambient exposures will further increase the demand for accurate and well-established EELs.

Predicting Chemical End-of-Life Scenarios Using Structure-Based Classification Models

Analyzing chemicals and their effects on the environment from a life cycle viewpoint can produce a thorough analysis that takes end-of-life (EoL) activities into account. Chemical risk assessment, predicting environmental discharges, and finding EoL paths and exposure scenarios all depend on chemical flow data availability. However, it is challenging to gain access to such data and systematically determine EoL activities and potential chemical exposure scenarios. As a result, this work creates quantitative structure-transfer relationship (QSTR) models for aiding environmental managment decision-making based on chemical structure-based machine learning (ML) models to predict potential industrial EoL activities, chemical flow allocation, environmental releases, and exposure routes. Further multi-label classification methods may improve the predictability of QSTR models according to the ML experiment tracking. The developed QSTR models will assist stakeholders in predicting and comprehending potential EoL management activities and recycling loops, enabling environmental decision-making and EoL exposure assessment for new or existing chemicals in the global marketplace.

Coupling a pathway-oriented approach with tailor-made monitoring as key to well-performing regionalized modelling of PFAS emissions and river concentrations

Surface water pollution with poly- and perfluorinated compounds (PFAS) is a well-recognized problem, but knowledge about contribution of different emission pathways, especially diffuse ones, is very limited. This study investigates the potential of the pathway oriented MoRE model in shedding light on the relevance of different emission pathways on regional scale and in predicting concentrations and loads in unmonitored rivers. Modelling was supported with a tailor-made monitoring programme aimed to fill gaps on PFAS concentration in different environmental compartments. The study area covers the whole Austrian territory including some additional transboundary catchments and it focuses on perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS). These two PFAS are regulated and therefore their production and use in Europe are currently decreasing. Nevertheless, these compounds are still emitted into the environment via legacy pollution and as transformation products from other PFAS. These two compounds were selected for this study in view of the larger information availability compared to other PFAS. Despite considerable uncertainties in the input data, model validations show that this approach performs significantly better than previous modelling frameworks based on population-specific emission factors, population density and wastewater treatment plant information. The study reveals the predominance of emissions via municipal wastewater treatment plants for PFOS and a relevant role of diffuse emission pathways for PFOA. Results suggest that unpaved areas contribute the biggest share to total diffuse emissions, but the estimation of these pathways is affected by the highest uncertainty in the input data and requires better input data from monitoring. Once the currently growing substance-specific data sets on the concentration of PFAS, others than PFOS and PFOA, in different environmental compartments, will reach an adequate quality, the model presented here will be easily applicable to them.

The potential of large floodplains to remove nitrate in river basins - The Danube case

Floodplains remove nitrate from rivers through denitrification and thus improve water quality. The Danube River Basin (DRB) has been affected by elevated nitrate concentrations and a massive loss of intact floodplains and the ecosystem services they provide. Restoration measures intend to secure and improve these valuable ecosystem services, including nitrate removal. Our study provides the first large-scale estimate of the function of large active floodplains in the DRB to remove riverine nitrate and assesses the contribution of reconnection measures. We applied a nutrient emission model in 6 river systems and coupled it with denitrification and flooding models which we adapted to floodplains. The floodplains have the capacity to eliminate about 33,200 t nitrate-N annually, which corresponds to 6.5 % of the total nitrogen emissions in the DRB. More nitrate is removed in-stream at regular flow conditions than in floodplain soils during floods. However, increasing frequently inundated floodplain areas reveals greater potential for improvement than increasing the channel network. In total, we estimate that 14.5 % more nitrate can be removed in reconnected floodplains. The largest share of nitrogen emissions is retained in the Yantra and Tisza floodplains, where reconnections are expected to have the greatest impact on water quality. In absolute numbers, the floodplains of the lower Danube convert the greatest quantities of nitrate, driven by the high input loads. These estimates are subject to uncertainties due to the heterogeneity of the available input data. Still, our results are within the range of similar studies. Reconnections of large floodplains in the DRB can, thus, make a distinct contribution to improving water quality. A better representation of the spatial configuration of water quality functions and the effect of floodplain reconnections may support the strategic planning of such to achieve multiple benefits and environmental targets.

Valorization of UWWTP effluents for ammonium recovery and MC elimination by advanced AOPs

The main objective of this study was to generate ready-to-use revalorized irrigation water for fertilization from urban wastewater treatment plant (UWWTP) effluents. The focus was on controlled retention of NH₄⁺ and microcontaminants (MC), using nanofiltration. Retentates generated were treated by solar photo-Fenton at circumneutral pH using Ethylenediamine-N, N'-disuccinic acid (EDDS) iron complexing agent. Solar photo-Fenton degradation efficacy was compared with electrooxidation processes as anodic oxidation, solar-assisted anodic oxidation, electro-Fenton and solar photoelectro Fenton. Finally, phytotoxicity and acute toxicity tests were performed to demonstrate the potentially safe reuse of treated wastewater for crop irrigation. Nanofiltration was able to produce a ready-to-use permeate stream containing recovered NH₄⁺. (valuable nutrient). Solar photo-Fenton treatment at circumneutral pH would only be of interest for rapid degradation of contaminants at less than 1 mg/L in nanofiltration retentates. Other alternative tertiary treatments, such as electrooxidation processes, are a promising alternative when a high concentration of MC requires longer process times. Anodic oxidation was demonstrated to be able to eliminate >80% of microcontaminants and solar-assisted anodic oxidation significantly reduced the electricity consumption. Electro-Fenton processes were the least efficient of the processes tested. Phytotoxicity results showed that irrigation with the permeates reduced germination, root development was mainly promoted and shoot development was positive only at low retention rate (concentration factor = 2). Acute and chronic Daphnia magna toxicity studies demonstrated that the permeate volumes should be diluted at least 50% before direct reuse for crop irrigation.

Ibuprofen exposure in Europe; ePiE as an alternative to costly environmental monitoring

The EU Water Framework Directive and Priority Substance Directive provide a framework to identify substances that potentially pose a risk to surface waters and provide a legal basis whereby member states are required to monitor and comply with environmental quality standards (EQSs) set for those substances. The cost and effort to continuously measure and analyse real world concentrations in all water bodies across Europe are high. Establishing the reliability of environmental exposure models to predict concentrations of priority substances is key, both to fill data gaps left by monitoring campaigns, and to predict the outcomes of actions that might be taken to reduce exposure. In this study, we aimed to validate the ePiE model for the pharmaceutical ibuprofen by comparing predictions made using the best possible consumption data with measured river concentrations. The results demonstrate that the ePiE model makes useful, conservative exposure predictions for ibuprofen, typically within a factor of 3 of mean measured values. This exercise was performed across a number of basins within Europe, representative of varying conditions, including consumption rates, population densities and climates. Incorporating specific information pertaining to the basin or country being assessed, such as custom WWTP removal rates, was found to improve the realism and accuracy of predictions. We found that the extrapolation of consumption data between countries should be kept to a minimum when modelling the exposure of pharmaceuticals, with the per capita consumption of ibuprofen varying by nearly a factor of 10.

Characterization of ecotoxicological risks from unintentional mixture exposures calculated from European freshwater monitoring data: Forwarding prospective chemical risk management

Current regulatory chemical safety assessments do not acknowledge that ambient exposures are to multiple chemicals at the same time. As a result, potentially harmful exposures to unintentional mixtures may occur, leading to potential insufficient protection of the environment. The present study describes cumulative environmental risk assessment results for European fresh water ecosystems, based on the NORMAN chemical surface water monitoring database (1998-2016). It aims to characterize the magnitude of the mixture problem and the relative contribution of chemicals to the mixture risk, and evaluates how cumulative risks reduce when the acceptable risk per single chemical is fractionally lowered. Available monitoring data were curated and aggregated to 26,631 place-time combinations with at least two chemicals, of which 376 place-time combinations had at least 25 chemicals identified above the Limit of Detection. Various risk metrics were based on measured environmental concentrations (MECs). Mixture risk characterization ratio's (ΣRCRs) ≥ 1 were found for 39% of the place-time combinations, with few chemicals dominating the ΣRCR. Analyses of mixture toxic pressures, expressed as multi-substance Potentially Affected Fractions of species based on No Observed Effect Concentrations (msPAF_NOEC), showed similar outcomes. Small fractional reductions of the ambient chemical concentrations give a steep increase of the percentage of sufficiently protected water bodies (i.e. ΣRCR < 1 and msPAF_NOEC < 5%). Scientific and regulatory aspects of these results are discussed, especially with reference to the representativeness of the monitoring data for characterizing ambient mixtures, the robustness of the findings, and the possible regulatory implementation of the concept of a Mixture Allocation Factor (MAF) for prospective chemicals risk management. Although the monitoring data do not represent the full spectrum of ambient mixture exposures in Europe, results show the need for adapting policies to reach European Union goals for a toxic-free environment and underpin the utility and possible magnitude of a MAF.

Micropollutants in urban wastewater: large-scale emission estimates and analysis of measured concentrations in the Baltic Sea catchment

Wastewater treatment plants (WWTPs) transmit many chemical contaminants to aquatic environments. Quantitative data on micropollutant emissions via WWTPs are needed for environmental risk assessments and evaluation of mitigation measures. This study compiled published data on substances analysed in effluents from WWTPs in the Baltic Sea region, assessed country related differences in the data sets and estimated micropollutant inputs to the Baltic Sea catchment. Concentration data were found for 1090 substances analysed at 650 WWTPs. Heterogeneity and low number of data points for most substances hindered adequate comparisons of country specific concentrations. Emission estimates were made for the 280 substances analysed in at least five WWTPs in years 2010 to 2019. For selected substances, mass loads were compared to previously published estimations. The study provides data useful for national and Baltic Sea-scale pressure analysis and risk assessments. However, it also highlights the need for broad scope monitoring of micropollutants in wastewater.

Estimating the release of chemical substances from consumer products, textiles and pharmaceuticals to wastewater

Chemical emissions from households originate from a wide range of sources and results in highly diverse mixtures. This makes traditional monitoring based on analytical chemistry challenging, especially for compounds that appear in low concentrations. We therefore developed a method for predicting emissions of chemicals from households into wastewater, relying on consumption patterns from multiple data sources. The method was then used to predict the emissions of chemical preparations, chemicals leaching from textiles and prescription pharmaceuticals in Sweden. In total we predicted emissions of 2007 chemicals with a combined emission of 62,659 tonnes per year - or 18 g/person and day. Of the emitted chemicals, 2.0% (w/w) were either classified as hazardous to the environment or were both persistent and mobile. We also show that chemical emissions come from a wide range of uses and that the total emission of any individual chemical is determined primarily by its use pattern, not by the total amount used. This emphasizes the need for continuous updates and additional knowledge generation both on emission factors and excretion rates as well as a need for improved reporting on the intended use of individual chemicals. Finally, we scrutinize the model and its uncertainty and suggest areas that need improvement to increase the accuracy of future emission modelling. We conclude that emission modelling can help guide environmental monitoring and provide input into management strategies aimed at reducing the environmental effect caused by hazardous chemicals.

Multi-parameter risk assessment of forty-one selected substances with endocrine disruptive properties in surface waters worldwide

The increasing use of substances with endocrine disruptive properties (EDs) not only impacts aquatic organisms but can also have a direct negative effect on human health. In this comprehensive worldwide review, we collected ecotoxicology and concentration data observed in surface water for 53 high-potency EDs and performed a risk assessment. The compounds were selected from the EU watchlist of priority substances, expanded with new compounds of emerging concern (total 41), where quantifiable data were available for the past three years (2018-2020). The risk quotients ranged from <0.01 for 22 substances to 1974 for tamoxifen. The frequency of samples in which the predicted no-effect concentrations were exceeded also varied, from 1.8% to 92.7%. By using the comprehensive multi-parameter risk assessment in our study, the most current to date, we determined that tamoxifen, imidacloprid, clothianidin, four bisphenols (BPA, BPF, BPS, and BPAF), PFOA, amoxicillin, and three steroid hormones (estriol, estrone, and cyproterone) pose significant risks in the environment. Comparing two structurally very similar bisphenols, BPA and BPB, suggested that the risk from BPB is currently underestimated by at least four orders of magnitude due to the lack of ecotoxicological data availability. The methodological limitations encountered suggest that a standardized methodology for data selection and assessment is necessary, highlighting the fact that some substances are currently under-represented in the field of ecotoxicological research. A new prioritization system is therefore presented, which provides a potential basis for new substances to be included in environmental monitoring lists.

Unfolding the synergy and interaction of water-land-food nexus for sustainable resource management: A supernetwork analysis

Given the large amounts of water, land, and food embodied in the trade of goods and services, a key step in decoupling extensive resource consumption from the economic system is to understand the full impact of socioeconomic development on the water-land-food nexus. This study integrates input-output analysis, ecological network analysis, and Dempster-Shafer evidence theory into a supernetwork model to detect the water-land-food nexus among economic sectors with an aim to explore effective strategic paths for resource management and to facilitate the construction of a resource-saving society. Results show that most sectors of China are resource inefficient and that all resource systems are unsustainable as reflected in the low performance of their Finn's cycling index and system robustness. Meanwhile, results of flow networks analysis show an extremely uneven land resource allocation where more than 94% of the land used in China is classified as direct agricultural land. The water-land-food nexus can gain resource saving bonus via enhancing the robustness of economy. However, the co-benefits from the nexus are negligibly small for the resource utilization efficiency. The results also indicate that the relevant resource-saving policies on food and water are highly likely to gain resource co-benefits due to their similarities in sectoral importance. Correspondingly, a set of strategic measures, including adopting a tiered resource price, deepening industrial convergence of agriculture, enhancing agriculture-food nexus, and managing water or land use from the food consumer side, are designed to build a resource-saving society. The findings of this study can provide additional insights into the impacts of the economy on the water-land-food nexus, which is beneficial for achieving an efficient and coordinated management of resources.

Uncertainty of chemical status in surface waters

This article addresses the issue of estimating P_om—the probability of misclassifying the chemical status confidence of a water body status assessment. The main concerns of the authors were chemical quality elements with concentrations in water bodies which are close to or even smaller than the limit of quantification (LOQ). Their values must be set to half of this limit to calculate the mean value. This procedure leads to very low standard deviation values and unrealistic values of P_om for chemical indicators. In turn, this may lead to the false conclusion that not only is the chemical status good but also that this status assessment is perfect. Therefore, for a more reliable calculation of P_om, the authors suggested a modified calculation in which the value of half the LOQ for calculating the mean value was kept, but zero as the concentration value for the standard deviation calculation was adopted. The proposed modification has been applied to the Hierarchical Approach procedure for P_om estimation of the chemical status of Polish rivers and lakes. The crucial finding is that current chemical status assessments may be incorrect in the case of approximately 25% of river water bodies and 30% of lake water bodies categorised as good, and 20% of both types of water bodies classified as below good.

Probability maps of anthropogenic impacts affecting ecological status in European rivers

Understanding how anthropogenic pressures affect river ecological status is pivotal to designing effective management strategies. Knowledge on river aquatic habitats status in Europe has increased tremendously since the introduction of the European Union Water Framework Directive, yet heterogeneities in mandatory monitoring and reporting still limit identification of patterns at continental scale. Concurrently, several model and data-based indicators of anthropogenic pressures to freshwater that cover the continent consistently have been developed. The objective of this work was to create European maps of the probability of occurrence of river conditions, namely failure to achieve good ecological status, or to be affected by specific pervasive impacts. To this end, we applied logistic regression methods to model the river conditions as functions of continental-scale water pressure indicators. The prediction capacity of the models varied with river condition: the probability to fail achieving good ecological status, and occurrence of nutrient and organic pollution were rather well predicted; conversely, chemical (other than nutrient and organic) pollution and alteration of habitats due to hydrological or morphological changes were poorly predicted. The most important indicators explaining river conditions were the shares of agricultural and artificial land, mean annual net abstractions, share of pollution loads from point sources, and the share of upstream river length uninterrupted by barriers. The probability of failing to achieve good ecological status was estimated to be high (>60%) for 36% of the considered river network of about 1.6 M km. Occurrence of impact of nutrient pollution was estimated high (>60%) in 26% of river length and that of organic pollution 20%. The maps are built upon information reported at country level pursuant EU legal obligations, as well as indicators generated from European scale models and data: both sources are affected by epistemic uncertainty. In particular, reported information depend on data collection scoping and schemes, as well as national knowledge and interpretation of river system pressures. In turn, water pressure indicators are affected by heterogeneous biases due to incomplete or incorrect inputs and uncertainty of models adopted. Lack of effective reach- and site-scale indicators may hamper detection of locally relevant impacts, for example in explaining alteration of habitats due to morphological changes. The probability maps provide a continental snapshot of current river conditions, and offer an alternative source of information on river aquatic habitats, which may help filling in knowledge gaps. Foremost, the analysis demonstrates the need for developing more effective continental-scale indicators for hydromorphological alterations and chemical pollution.

Calibration and field application of the Atlantic HLB Disk containing Chemcatcher® passive sampler - Quantitative monitoring of herbicides, other pesticides, and transformation products in German streams

The Chemcatcher® (CC) passive sampler containing an Atlantic HLB-L Disk (AD) was calibrated in a laboratory-based flow-through tank over 21 days under stirring for 38 polar organic pesticides with log K_ow ranging from -1.7 to 3.8. The resultant sampling rates R_s range from 0.025 to 0.068 L/d. In 2018, field trials were conducted in the German rivers Mulde and Havel, as well as in 7 agricultural streams in Lower Saxony and Saxony-Anhalt. For 36 detected pesticides, the overall low concentrations were 0.2 to 49.4 ng/L. The determined pesticide profiles reflect agricultural use and were dominated by triazine herbicides including transformation products, by neonicotinoid insecticides, and by the herbicide mecoprop. Additional single hot spots were provided by the herbicides metamitron, isoproturon, and MCPA (showing the overall largest value of 49.4 ng/L). Notably, the detected waterborne pesticides include banned herbicides and associated transformation products in concentration ratios suggesting also recent input. This concerns in particular atrazine and its transformation products 2-OH-atrazine, deethylatrazine and deisopropylatrazine. An extended target screening of AD-CC extracts from the river Havel revealed the additional presence of other organic micropollutants including biocides, surfactants and industrial chemicals, and demonstrated the AD-CC applicability up to log K_ow of 4.5.

Multiple stressors determine river ecological status at the European scale: Towards an integrated understanding of river status deterioration

The biota of European rivers are affected by a wide range of stressors impairing water quality and hydro-morphology. Only about 40% of Europe's rivers reach 'good ecological status', a target set by the European Water Framework Directive (WFD) and indicated by the biota. It is yet unknown how the different stressors in concert impact ecological status and how the relationship between stressors and status differs between river types. We linked the intensity of seven stressors to recently measured ecological status data for more than 50,000 sub-catchment units (covering almost 80% of Europe's surface area), which were distributed among 12 broad river types. Stressor data were either derived from remote sensing data (extent of urban and agricultural land use in the riparian zone) or modelled (alteration of mean annual flow and of base flow, total phosphorous load, total nitrogen load and mixture toxic pressure, a composite metric for toxic substances), while data on ecological status were taken from national statutory reporting of the second WFD River Basin Management Plans for the years 2010-2015. We used Boosted Regression Trees to link ecological status to stressor intensities. The stressors explained on average 61% of deviance in ecological status for the 12 individual river types, with all seven stressors contributing considerably to this explanation. On average, 39.4% of the deviance was explained by altered hydro-morphology (morphology: 23.2%; hydrology: 16.2%), 34.4% by nutrient enrichment and 26.2% by toxic substances. More than half of the total deviance was explained by stressor interaction, with nutrient enrichment and toxic substances interacting most frequently and strongly. Our results underline that the biota of all European river types are determined by co-occurring and interacting multiple stressors, lending support to the conclusion that fundamental management strategies at the catchment scale are required to reach the ambitious objective of good ecological status of surface waters.

Storm Event-Driven Occurrence and Transport of Dissolved and Sorbed Organic Micropollutants and Associated Effects in the Ammer River, Southwestern Germany

Storm events lead to agricultural and urban runoff, to mobilization of contaminated particulate matter, and to input from combined sewer overflows into rivers. We conducted time-resolved sampling during a storm event at the Ammer River, southwest Germany, which is representative of small river systems in densely populated areas with a temperate climate. Suspended particulate matter (SPM) and water from 2 sampling sites were separately analyzed by a multi-analyte liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for 97 environmentally relevant organic micropollutants and with 2 in vitro bioassays. Oxidative stress response (AREc32) may become activated by various stressors covering a broad range of physicochemical properties and induction of aryl hydrocarbon receptor-chemical-activated luciferase gene expression (AhR-CALUX) by hydrophobic compounds such as dioxins and dioxin-like molecules. Compound numbers, concentrations, their mass fluxes, and associated effect fluxes increased substantially during the storm event. Micropollutants detected in water and on SPM pointed toward inputs from combined sewer overflow (e.g., caffeine, paracetamol), urban runoff (e.g., mecoprop, terbutryn), and agricultural areas (e.g., azoxystrobin, bentazone). Particle-facilitated transport of triphenylphosphate and tris(1-chloro-2-propyl) phosphate accounted for up to 34 and 33% of the total mass flux even though SPM concentrations were <1 g L^-1 . Effect fluxes attributed to SPM were similar or higher than in the water phase. The important role of SPM-bound transport emphasizes the need to consider not only concentrations but also mass and effect fluxes for surface water quality assessment and wastewater/stormwater treatment options. Environ Toxicol Chem 2021;40:88-99. © 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Environmental prioritization of pesticide in the Upper Citarum River Basin, Indonesia, using predicted and measured concentrations

A novel screening method was developed to prioritize aquatic and human health risks of pesticides based on usage data, runoff modelling and effect prediction. An important asset of this new method is that it does not require measured concentration data, which are often unavailable or difficult to obtain in low- and middle-income countries like Indonesia. The method was applied to prioritize 31 agricultural pesticides used in the Upper Citarum River Basin in West Java, Indonesia. Ranking of pesticides based on predicted concentrations generally showed good agreement with ranking based on concentrations measured by passive sampling. The individual pesticide intake through the consumption of river water was predicted to cause negligible human health risks, but substantial aquatic risks (i.e. PEC/PNEC >1) were predicted for profenofos (5.2.E+01), propineb (3.6.E+01), chlorpyrifos (2.6.E+01), carbofuran (1.7.E+01), imidacloprid (9.4.E+00), methomyl (7.6.E+00) and chlorantraniliprole (3.6.E+00). In order to protect the aquatic environment, water managers are advised to take measures to reduce the use and runoff of these pesticides in the UCRB. The screening assessment can be further refined by performing additional effect studies for some pesticides, pesticide mixtures and validation of the predicted water concentrations by targeted measurements.

Chemical pollution imposes limitations to the ecological status of European surface waters

Aquatic ecosystems are affected by man-made pressures, often causing combined impacts. The analysis of the impacts of chemical pollution is however commonly separate from that of other pressures and their impacts. This evolved from differences in the data available for applied ecology vis-à-vis applied ecotoxicology, which are field gradients and laboratory toxicity tests, respectively. With this study, we demonstrate that the current approach of chemical impact assessment, consisting of comparing measured concentrations to protective environmental quality standards for individual chemicals, is not optimal. In reply, and preparing for a method that would enable the comprehensive assessment and management of water quality pressures, we evaluate various quantitative chemical pollution pressure metrics for mixtures of chemicals in a case study with 24 priority substances of Europe-wide concern. We demonstrate why current methods are sub-optimal for water quality management prioritization and that chemical pollution currently imposes limitations to the ecological status of European surface waters. We discuss why management efforts may currently fail to restore a good ecological status, given that to date only 0.2% of the compounds in trade are considered in European water quality assessment and management.

Screening-Level Estimates of Environmental Release Rates, Predicted Exposures, and Toxic Pressures of Currently Used Chemicals

We describe a procedure to quantify emissions of chemicals for environmental protection, assessment, and management purposes. The procedure uses production and use volumes from registration dossiers and combines these with Specific Environmental Release Category data. The procedure was applied in a case study. Emission estimations were made for chemicals registered under the European Union chemicals regulations for industrial chemicals (Registration, Evaluation, Authorisation and Restriction of Chemicals [REACH]) and for the active ingredients of medicines and crop protection products. Emissions themselves cannot be validated. Instead, emission estimates were followed by multimedia fate modeling and mixture toxic pressure modeling to arrive at predicted environmental concentrations (PECs) and toxic pressures for a typical European water body at steady state, which were compared with other such data. The results show that screening-level assessments could be performed, and yielded estimates of emissions, PECs, and mixture toxic pressures of chemicals used in Europe. Steady-state PECs agreed fairly well with measured concentrations. The mixture toxic pressure at steady state suggests the presence of effects in aquatic species assemblages, whereby few compounds dominate the predicted impact. The study shows that our screening-level emission estimation procedure is sufficiently accurate and precise to serve as a basis for assessment of chemical pollution in aquatic ecosystems at the scale of river catchments. Given a recognized societal need to develop methods for realistic, cumulative exposures, the emission assessment procedure can assist in the prioritization of chemicals in safety policies (such as the European Union REACH regulation), where "possibility to be used safely" needs to be demonstrated, and environmental quality policies (such as the European Union Water Framework Directive), where "good environmental quality" needs to be reached. Environ Toxicol Chem 2020;39:1839-1851. © 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.