The present study is the first comprehensive monitoring of 13 selected endocrine disrupting compounds (EDCs) in untreated urban and industrial wastewater in Serbia to assess their impact on the ...Danube River basin and associated freshwaters used as sources for drinking water production in the area. Results showed that natural and synthetic estrogens were present in surface and wastewater at concentrations ranging from 0.1 to 64.8 ng L−1. Nevertheless, they were not detected in drinking water. For alkylphenols concentrations ranged from 1.1 to 78.3 ng L−1 in wastewater and from 0.1 to 37.2 ng L−1 in surface water, while in drinking water concentrations varied from 0.4 to 7.9 ng L−1. Bisphenol A (BPA) was the most abundant compound in all water types, with frequencies of detection ranging from 57% in drinking water, to 70% in surface and 84% in wastewater. Potential environmental risks were characterized by calculating the risk quotients (RQs) and the estrogenic activity of EDCs in waste, surface and drinking water samples, as an indicator of their potential detrimental effects. RQ values of estrone (E1) and estradiol (E2) were the highest, exceeding the threshold value of 1 in 60% of wastewater samples, while in surface water E1 displayed potential risks in only two samples. Total estrogenic activity (EEQt) surpassed the threshold of 1 ng E2 L−1 in about 67% of wastewater samples, and in 3 surface water samples. In drinking water, EEQt was below 1 ng L−1 in all samples.
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•Occurrence and risk assessment of 13 EDCs was evaluated in three water types from Serbia.•BPA was the most abundant compound riched 338 ng L−1 in analyzed wastewater samples.•EEQt surpassed threshold of 1 ng L−1 in 67% (10%) of waste (surface) water samples.•EDCs present in drinking water might not induce negative effects on human health.
Averaged 7-day composite effluent wastewater samples from twelve wastewater treatment plants (WWTPs) in nine countries (Romania, Serbia, Hungary, Slovenia, Croatia, Slovakia, Czechia, Austria, ...Germany) in the Danube River Basin were collected. WWTPs' selection was based on countries' dominant technology and a number of served population with the aim to get a representative holistic view of the pollution status. Samples were analyzed for 2248 chemicals of emerging concern (CECs) by wide-scope target screening employing LC-ESI-QTOF-MS. 280 compounds were detected at least in one sample and quantified. Spatial differences in the concentrations and distribution of the compounds classes were discussed. Additionally, samples were analyzed for the possible agonistic/antagonistic potencies using a panel of in vitro transactivation reporter gene CALUX® bioassays including ERα (estrogenics), anti-AR (anti-androgens), GR (glucocorticoids), anti-PR (anti-progestins), PPARα and PPARγ (peroxisome proliferators) and PAH assays. The potency of the wastewater samples to cause oxidative stress and induce xenobiotic metabolism was determined using the Nrf2 and PXR CALUX® bioassays, respectively. The signals from each of the bioassays were compared with the recently developed effect-based trigger values (EBTs) and thus allowed for allocating the wastewater effluents into four categories based on their measured toxicity, proposing a putative action plan for wastewater operators. Moreover, samples were analyzed for antibiotics and 13 antibiotic-resistant genes (ARGs) and one mobile genetic element (intl1) with the aim to assess the potential for antibiotic resistance. All data collected from these various types of analysis were stored in an on-line database and can be viewed via interactive map at https://norman-data.eu/EWW_DANUBE.
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•280 out of 2248 target substances were detected.•Detected chemicals were evaluated based on their ecotoxicological properties.•10 in vitro bioassays were applied for assessing the adverse effects in wastewater.•Effect-based risk assessment of WWTP effluents was applied.•13 antibiotic resistant genes were determined in the Danube River Basin.
Per- and polyfluoroalkyl substances (PFAS) are under regulatory scrutiny since some of them are persistent, bioaccumulative, and toxic. The occurrence of 4777 PFAS was investigated in the Danube ...River Basin (DRB; 11 countries) using target and suspect screening. Target screening involved investigation of PFAS with 56 commercially available reference standards. Suspect screening covered 4777 PFAS retrieved from the NORMAN Substance Database, including all individual PFAS lists submitted to the NORMAN Suspect List Exchange Database. Mass spectrometry fragmentation patterns and retention time index predictions of the studied PFAS were established for their screening by liquid chromatography – high resolution mass spectrometry using NORMAN Digital Sample Freezing Platform (DSFP). In total, 82 PFAS were detected in the studied 95 samples of river water, wastewater, groundwater, biota and sediments. Suspect screening detected 72 PFAS that were missed by target screening. Predicted no effect concentrations (PNECs) were derived for each PFAS via a quantitative structure-toxicity relationship (QSTR)-based approach and used for assessment of their environmental risk. Risk characterization revealed 18 PFAS of environmental concern in at least one matrix. The presence of PFAS in all studied environmental compartments across the DRB indicates a potentially large-scale migration of PFAS in Europe, which might require their further systematic regulatory monitoring.
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•82 PFAS were identified in environmental samples from the Danube River Basin.•Suspect screening identified additional 72 PFAS compared to target screening.•Risk assessment identified 18 PFAS of environmental concern.•17 out of the 18 PFAS of environmental concern are currently not regulated.•PFAS groups (by functional groups) did not show significant differences in PNEC.
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.
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•A first estimate of the NO3 removal by large floodplains in the Danube River Basin.•We coupled a nutrient emission-, a denitrification-, and a flooding model.•Currently, active floodplains can remove ~33,200 t NO3-N (≙6.5 % of N emissions).•Reconnections could increase this by 9–32 %, besides other ecological improvements.•Assessing water quality functions supports the planning of floodplain restorations.
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•The Joint Danube Survey highlights the need for long-term, harmonised water quality data sets to facilitate management at a basin scale.•Long-term datasets can be used to optimise ...future monitoring programme design.•Large river basin monitoring programmes must respond to new challenges from emerging contaminants and future climate impacts.
Effective management of water quality in large rivers requires information on the influence of activities within the catchment (urban and rural) throughout the whole river basin. However, traditional water quality monitoring programmes undertaken by individual agencies normally relate to specific objectives, such as meeting quality criteria for wastewater discharges, and fail to provide information on basin-scale impacts, especially in transboundary river basins. Ideally, monitoring in large international river basins should be harmonised to provide a basin-scale assessment of sources and impacts of human activities, and the effectiveness of management actions. This paper examines current water quality issues in the Danube River Basin and evaluates the approach to water quality monitoring in the context of providing information for a basin-wide management plan. Lessons learned from the monitoring programme in the Danube are used to suggest alternative approaches that could result in more efficient generation of water quality data and provide new insights into causes and impacts of variations in water quality in other large international river basins.
Floodplains provide ecosystem services (ES). Their evaluation is complex and integrative assessment remains challenging for sciences and practices. Studies have been published in the last two decades ...reporting ES monetary values of floodplains. Since ES are site-specific, we focus on those studies regarding the Europe's second largest river basin, namely the Danube River Basin (DRB). By analyzing these studies, we aim to answer the questions: “Do the significant predictor variables differ from previous meta-analyses?” and “Does the spatial database improve the meta-analysis?” In this context, we conducted a systematic review on Scopus and Web of Science combining the four themes “value”, “ES”, “floodplain”, and “location”. We conducted a meta-analysis of the Danube floodplains' ES values with different sub-groups based on the ES classes (provisioning, regulating, and cultural) and implemented model selection based on the corrected Akaike Information Criterion. We selected 251 entries from 25 studies to set up with a PostgreSQL spatial database, which provides limitless possibilities to enrich the information on the study areas. We observed that the most important variables to describe ES values of DRB floodplains depend on the ES class, but in general the area proportions of water bodies and riparian landscapes are important, together with the valuation method and the chemical or ecological status of the corresponding river section. Finally, we provided two versions of unconditional benefit-transfer functions to evaluate provisioning, regulating, and cultural ES. This paper complements previously conducted meta-analyses to recognize significant characteristics to value ES and it is a valid basis to help determine the ES value of Danube floodplains.
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•Search of studies on ecosystem services values of floodplains in Danube countries•A spatial database stores the search results and connects them to additional data.•Multi (mixed-effects-)model inference produces reliable benefit transfer functions.•A fast valuation of Danube floodplains' ecosystem services is now possible.
Large‐scale hydrological models are nowadays mostly calibrated using observed discharge. As a result, a large part of the hydrological system, in particular the unsaturated zone, remains ...uncalibrated. Soil moisture observations from satellites have the potential to fill this gap. Here we evaluate the added value of remotely sensed soil moisture in calibration of large‐scale hydrological models by addressing two research questions: (1) Which parameters of hydrological models can be identified by calibration with remotely sensed soil moisture? (2) Does calibration with remotely sensed soil moisture lead to an improved calibration of hydrological models compared to calibration based only on discharge observations, such that this leads to improved simulations of soil moisture content and discharge? A dual state and parameter Ensemble Kalman Filter is used to calibrate the hydrological model LISFLOOD for the Upper Danube. Calibration is done using discharge and remotely sensed soil moisture acquired by AMSR‐E, SMOS, and ASCAT. Calibration with discharge data improves the estimation of groundwater and routing parameters. Calibration with only remotely sensed soil moisture results in an accurate identification of parameters related to land‐surface processes. For the Upper Danube upstream area up to 40,000 km2, calibration on both discharge and soil moisture results in a reduction by 10–30% in the RMSE for discharge simulations, compared to calibration on discharge alone. The conclusion is that remotely sensed soil moisture holds potential for calibration of hydrological models, leading to a better simulation of soil moisture content throughout the catchment and a better simulation of discharge in upstream areas.
Key Points
Satellite soil moisture holds potential for calibration of hydrological models
Soil moisture observations enable better calibration of land‐surface parameters
Errors in discharge simulations are reduced using soil moisture for calibration
•586 of the studied 2362 contaminants were detected in the Danube River Basin.•Risk assessment prioritized 12 legacy and 33 emerging contaminants.•The 33 emerging contaminants are Danube River Basin ...Specific Pollutants.•20 performance indicators were checked in wastewater treatment plants.•The plants showed medium or efficient removal for 70% of the studied compounds.
A state-of-the-art wide-scope target screening of 2,362 chemicals and their transformation products (TPs) was performed in samples collected within the Joint Danube Survey 4 (JDS4) performed in 2019. The analysed contaminants of emerging concern (CECs) included three major categories: plant protection products (PPPs), industrial chemicals and pharmaceuticals and personal care products (PPCPs). In total, 586 CECs were detected in the samples including 158 PPPs, 71 industrial chemicals, 348 PPCPs, and 9 other chemicals. A wide-variety of sample matrices were collected including influent and effluent wastewater, groundwater, river water, sediment and biota. Forty-five CECs (19 PPPs, 8 industrial chemicals, 18 PPCPs) were detected at levels above their ecotoxicological thresholds (lowest predicted no-effect concentration (PNEC) values) in one or more of the investigated environmental compartments, indicating potential adverse effects on the impacted ecosystems. Among them 12 are legacy substances; 33 are emerging and qualify as potential Danube River Basin Specific Pollutants (RBSPs). Moreover, the efficiency of the wastewater treatment plants (WWTPs) was evaluated using 20 selected performance indicator chemicals. WWTPs showed effective removal (removal rate ≥80%) and medium removal (removal rate 25–80%) for 6 and 8 of the indicator chemicals, respectively. However, numerous contaminants passed the WWTPs with a lower removal rate. Further investigation on performance of WWTPs is suggested at catchment level to improve their removal efficiency. WWTP effluents are proven to be one of the major sources of contaminants in the Danube River Basin (DRB). Other sources include sewage discharges, industrial and agricultural activities. Continuous monitoring of the detected CECs is suggested to ensure water quality of the studied area.
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Water, food and energy are at the core of human needs and there is a boundless complex cycle among these three basic human needs. Ecosystems are in the center of this nexus, since they contribute to ...the provision of each component, making it imperative to understand the role of ecosystems in securing food, water and energy for human well-being. In this study we aimed to map and assess water provisioning services and associated benefits to support the ecosystem–water–food–energy nexus by taking into account environmental flow requirements for riverine ecosystems using the hydrological model Soil and Water Assessment Tool (SWAT). We developed a framework that includes indicators of renewable water (capacity of ecosystem to provide water) and water use (service flow) and we applied it in the Danube river basin over the period 1995–2004. Water scarcity indicators were used to map the possible water scarcity in the subbasins, and analyze the spatial match of water availability and water use. The results show that modelling is instrumental to perform the integrated analysis of the ecosystem–water–food–energy nexus; and that spatial mapping is a powerful tool to display environmental availability of water provisioning and regulatory services delivered by ecosystems, and can support the nexus analysis.
•Efficient water management requires spatial knowledge of water availability and use•We develop an approach for assessing and mapping water provisioning services•We implement the approach in the Danube river basin.•The approach can support assessments and policies related to the ecosystem–water–food–energy nexus
The long-term runoff variability is identified to consist of the selected large rivers with long-term data series in the Danube River Basin. The rivers were selected in different regions of the ...Danube River Basin and have a large basin area (Danube: Bratislava gauge with 131,338 km
; Tisza: Senta with 141,715 km
; and Sava: Sremska Mitrovica with 87,966 km
). We worked with the station Danube: Reni in the delta as well. A spectral analysis was used to identify the long-term variability of three different types of time series: (1) Average annual discharge time series, (2) Minimum annual discharge time series and (3) Maximum annual discharge time series. The results of the study can be used in a long-term forecast of the runoff regime in the future.
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