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Urban wastewater inputs are a relevant pollution source to rivers, contributing a complex mixture of nutrients, organic matter and organic microcontaminants to these systems. Depending on their composition, WWTP effluents might perform either as enhancers (subsidizers) or inhibitors (stressors) of biological activities. In this study, we evaluated in which manner biofilms were affected by treated urban WWTP effluent, and how much they recovered after exposure was terminated. We used indoor artificial streams in a replicated regression design, which were operated for a total period of 56 days. During the first 33 days, artificial streams were fed with increasing concentration of treated effluents starting with non-contaminated water and ending with undiluted effluent. During the recovery phase, the artificial streams were fed with unpolluted water. Sewage effluents contained high concentrations of personal care products, pharmaceuticals, nutrients, and dissolved organic matter. Changes in community structure, biomass, and biofilm function were most pronounced in those biofilms exposed to 58% to 100% of WWTP effluent, moving from linear to quadratic or cubic response patterns. The return to initial conditions did not allow for complete biofilm recovery, but biofilms from the former medium diluted treatments were the most benefited (enhanced response), while those from the undiluted treatments showed higher stress (inhibited response). Our results indicated that the effects caused by WWTP effluent discharge on biofilm structure and function respond to the chemical pressure only in part, and that the biofilm dynamics (changes in community composition, increase in thickness) imprint particular response pathways over time. © 2019 Elsevier B.V., This study has been financially supported by the EU FP7 project GLOBAQUA [Grant Agreement No. 603629] and by the Generalitat de Catalunya [Consolidated Research Groups: 2017 SGR 01404−Water and Soil Quality Unit]. NM thanks SCIEX for generously providing the loaned instrument. Authors are grateful to Vicenç Acuña, Maria Casellas, Ferran Romero and Olatz Pereda for their support and advice during the experiment, and to Peter Eichhorn for his critical reading of the manuscript.

The use of chemicals is continuously growing both in total amount as well as in a number of different substances, among which organic chemicals play a major role. Owing to the growing public awareness on the need of protecting both ecosystems and human health from the risks related to chemical pollution, an increasing attention has been drowned to risk assessment and prioritization of organic pollutants. In this context, the aims of this study were (a) to perform an environmental risk assessment for 200 organic micropollutants including both regulated and emerging contaminants (pesticides, alkylphenols, pharmaceuticals, hormones, personal care products, perflourinated compounds and various industrial organic chemicals) monitored in four rivers located in the Mediterranean side of the Iberian Peninsula, namely, the Ebro, Llobregat, Júcar and Guadalquivir rivers; and (b) to prioritize them for each of the four river basins studied, taking into account their observed concentration levels together with their ecotoxicological potential. For this purpose, a prioritization approach has been developed and a resulting ranking index (RI) associated with each compound. Ranking index is based on the measured concentrations of the chemical in each river and its ecotoxicological potential (EC50 values for algae, Daphnia sp. and fish). Ten compounds were identified as most important for the studied rivers: pesticides chlorpyriphos, chlorfenvinphos, diazinon, dichlofenthion, prochloraz, ethion carbofuran and diuron and the industrial organic chemicals nonylphenol and octylphenol that result from the biodegration of polyethoxylated alkyphenol surfactants. Also, further research into chronic toxicity of emerging contaminants is advocated Thisworkwas funded by the SpanishMinistry of Economy and Competitiveness project Consolider-Ingenio 2010 SCARCE CSD2009-00065 and by the Generalitat de Catalunya (Consolidated Research Groups “2014 SGR 418–Water and Soil Quality Unit” and 2014 SGR 291–ICRA)

Mediterranean rivers are characterized by highly variable hydrological regimes that are strongly dependent on the seasonal rainfall. Sediment transport is closely related to the occurrence of flash-floods capable to deliver enough kinetic energy to mobilize the bed and channel sediments. Contaminants accumulated in the sediments are likely to be mobilized as well during such events. However, whereas there are many studies characterizing contaminants in steady sediments, those devoted to the transport dynamics of suspended-sediment borne pollution are lacking. Here we examined the occurrence and transport of persistent organic microcontaminants present in the circulating suspended sediments during a controlled flushing flow in the low part of the River Ebro (NE Spain) 12km downstream of a well-known contaminated hot-spot associated to a nearby chloro-alkali industry. Polycyclic aromatic hydrocarbons (PAHs) and semi-volatile organochlorine pollutants (DDT and related compounds, DDX; polychlorinated byphenils, PCBs; and other organochlorine compound, OCs) were measured in the particulate material by GC-MS and GC-MS/MS, using previously developed analytical methods. The concentration levels observed were compared to previously reported values in steady sediments in the same river and discussed on a regulatory perspective. Hydrographs and sedigraphs recorded showed a peak-flow of 1300m3s-1 and a corresponding peak of suspended sediments of 315mgL-1. Combination of flow discharge, suspended sediments and pollutants' concentrations data allowed for quantifying the mass flows (mass per unit of time) and setting the load budgets (weight amount) of the different pollutants transported by the river during the monitored event. Mean mass-flows and total load values found were 20.2mgs-1 (400g) for PAHs, 38mgs-1 (940g) for DDX, 44mgs-1 (1038g) for PCBs and 8mgs-1 (200g) for OCs. The dynamic pattern behavior of PAHs differs substantially to that of organochlorine pollutants, thus reflecting different pollution origins., This work was supported by the Spanish Ministry of Economy and Competitiveness through the Consolider-Ingenio 2010 project SCARCE (CSD2009-00065) and by the Generalitat de Catalunya (Consolidated Research Group: Water and Soil Quality Unit 2009-SGR-965). The research leading to these results has received funding from the European Comunities 7th Framework Programme under Grant Agreement No. 603629-ENV-2013-6.2.1-Globaqua.

In the last decade the political awareness of river water quality issues has grown substantially over the world and legislation is accordingly adapting. In the European Union (EU), two different directives regulate separately the characteristics of the discharged water and the chemical status of the receiving freshwater ecosystem. On the one hand, the characteristics of the urban effluents are regulated by the EU Directive 91/271/EEC, which defines limits on different elements set in the form of both static emission limits and minimum percentage load reductions. On the other hand, the characteristics of the receiving freshwater ecosystems are described in the EU Water Framework Directive (2000/60/EEC), which sets minimum 'good' chemical and ecological status in water bodies that should be achieved by 2015, and aims for an ecosystem-based management. With the support of an example, we show that there is a gap in these EU environmental policies leading to non-integrated management, which may result on adverse environmental and economical consequences. We believe that these policies should be updated and tuned to account for an integrated perspective, allowing a more efficient and sustainable management of wastewater treatment plants, maximizing the ecological, economical and social benefits of the system as a whole This research was supported by a Marie Curie Career Integration Grant (PCIG9-GA-2011-293535) and by a Marie Curie European Reintegration Grant (PERG07-GA-2010-259219) within the 7th European Community Framework Programme, aswell as by the Spanish Ministry of Economy and Competitiveness for its financial support through the projects ENDERUS (CTM-2009-13018) and SCARCE (Consolider-Ingenio 2010 CSD2009-00065) and the postdoctoral grant “Juan de la Cierva” (jci-2009-05604). The authors would like to thank the “Consorci per la Defensa de la Conca del Riu Besòs” (CDCRB) for providing the data of the Garriga system

The objective of this study was to determine different brominated flame retardants (BFRs) in sewage sludge produced in 17 wastewater treatment plants (WWTPs) located in the Northeast of Spain. A total of eight polybrominated diphenyl ether (PBDE) congeners, from tri- to deca-BDEs, were analyzed. The emerging BFR compounds, hexabromobenzene (HBB), pentabromoethylbenzene (PBEB) and decabromodiphenylethane (DBDPE) were also analyzed. The instrumental methodology for the analysis was based on gas chromatography coupled to mass spectrometry with negative chemical ionization (GC-NICI-MS). Moreover, liquid cromathography-quadrupole linear ion trap mass spectrometry (LC-QqLIT-MS/MS) was applied for the determination of hexabromocyclododecanes (HBCDs), tetrabromobisphenol A (TBBPA) and their related compounds, bisphenol A (BPA), monobromobisphenol A (MonoBBPA), dibromobisphenol A (DiBBPA) and tribromobisphenol A (TriBBPA). The most abundant PBDE congener in these sewage sludge samples was BDE-209, with levels ranging from nd to 2303 ng/g dw. In addition, a significant concentrations of DBDPE were also detected, nd-257 ng/g dw, due to their increase production as a Deca-BDE substitute. The emerging compounds HBB and PBEB were detected in 4 WWTPs and their concentrations ranged between nd-5.71 and nd-2.33 ng/g, respectively. TBBPA was detected in quantifiable levels in 15 of the 17 WWTPs analyzed, in concentration range of nd-472 ng/g dw, whereas HBCDs were only found in 8 WWTPs in lower concentrations, between nd and 97.5 ng/g dw. Based on the analysis of sewage sludge samples from different WWTPs and in order to evaluate the impact of these contaminants in the environment, an estimation of BFRs accumulated in the total sewage sludge produced in Catalonia was carried out, with values of 57.8 kg/year, 6.76 kg/year, 13.5 kg/year, 1.56 kg/year, 0.18 kg/year and 0.02 kg/year for PBDEs, DBDPE, TBBPA, HBCDs, HBB and PBEB respectively.

Given the huge number of chemicals released into the environment and existing time and budget constraints, there is a need to prioritize chemicals for risk assessment and monitoring in the context of the European Union Water Framework Directive (EU WFD). This study is the first to assess the risk of 500 organic substances based on observations in the four European river basins of the Elbe, Scheldt, Danube and Llobregat. A decision tree is introduced that first classifies chemicals into six categories depending on the information available, which allows water managers to focus on the next steps (e.g. derivation of Environmental Quality Standards (EQS), improvement of analytical methods, etc.). The priority within each category is then evaluated based on two indicators, the Frequency of Exceedance and the Extent of Exceedance of Predicted No-Effect Concentrations (PNECs). These two indictors are based on maximum environmental concentrations (MEC), rather than the commonly used statistically based averages (Predicted Effect Concentration, PEC), and compared to the lowest acute-based (PNECacute) or chronic-based thresholds (PNECchronic). For 56% of the compounds, PNECs were available from existing risk assessments, and the majority of these PNECs were derived from chronic toxicity data or simulated ecosystem studies (mesocosm) with rather low assessment factors. The limitations of this concept for risk assessment purposes are discussed. For the remainder, provisional PNECs (P-PNECs) were established from read-across models for acute toxicity to the standard test organisms Daphnia magna, Pimephales promelas and Selenastrum capricornutum. On the one hand, the prioritization revealed that about three-quarter of the 44 substances with MEC/PNEC ratios above ten were pesticides. On the other hand, based on the monitoring data used in this study, no risk with regard to the water phase could be found for eight of the 41 priority substances, indicating a first success of the implementation of the WFD in the investigated river basins. © 2011 Elsevier B.V., The presented prioritization approach was developed within the NORMAN Association (No. W604002510) working group on prioritization of emerging substances (WG 1) and was approved by the WG members present at the WG meeting in Paris (22–23 November 2010). The work was supported by the European Commission through the Integrated Projects MODELKEY (Contract-No. 511237GOCE) and OSIRIS (contract No. 037017). Peter C. von der Ohe was financially supported through a Deutsche Forschungsgemeinschaft (DFG) postdoctoral fellowship (PAK 406/1). The authors would like to acknowledge the International Commission for the Protection of the Danube River and the team of experts and laboratories providing the data from the Joint Danube Survey 2 as well as the Landesbetriebes für Hochwasserschutz und Wasserwirtschaft Sachsen-Anhalt (Gen. LHW/5.4/003/2006), the Sächsisches Landesamt für Umwelt und Geologie (LfUG, Dresden, Germany), the Vlaamse Milieumaatschappij (VMM, Erembodegem, Aalst, Belgium) and the Agencia Catalana de l'Aigua (ACA, Barcelona, Spain) who kindly provided the monitoring data used for the application of the methodology. Emma L. Schymanski is thanked for valuable suggestions that improved the manuscript.