Occurrence of priority and emerging organic compounds in fishes from the Rhone River (France).

The main objective of this study was to collect new data on the occurrence, levels of priority and emerging organic compounds in freshwater fish sampled in the Rhone River. The 34 studied contaminants included alkylphenols, bisphenol A, polybromodiphenylethers (PBDE), perfluorinated compounds, hexabromocyclododecanes (HBCD), hexachlorobenzene and hexachlorobutadiene (HCBD). About 50 fish samples (individual specimens or pooled fish) were collected from three sites located upstream and downstream of the Lyon metropolitan area in the Rhone River (France). Four species were caught at each site, namely: the barbel (Barbus barbus), the common bream (Abramis brama), the white bream (Blicca bjoerkna) and the chub (Squalius cephalus). Some contaminants were quantified in all the 32 fish samples analysed: 4-nonylphenol, α-HBCD, the six PBDE congeners (28, 47, 99, 100, 153, 154), perfluorooctanesulfonate (PFOS) and perfluorodecanoic acid. Twenty three of the 32 samples had a concentration of PFOS above the Environmental Quality Standards (EQS) (up to six times higher than the EQS), and all the 32 samples had concentrations of PBDE above the EQS (up to 4,000 times higher, with the sum of six PBDE varying from 4.5 to 182 ng/g dry weight). Clearly, the interest to consider PFOS and HBCD as new priority substances is confirmed. In contrast, the pertinence of a priority status for HCBD, which was never quantified in our study, might have to be reconsidered in the future.

Occurrence and fate of relevant substances in wastewater treatment plants regarding Water Framework Directive and future legislations.

The next challenge of wastewater treatment is to reliably remove micropollutants at the microgram per litre range. During the present work more than 100 substances were analysed through on-site mass balances over 19 municipal wastewater treatment lines. The most relevant substances according to their occurrence in raw wastewater, in treated wastewater and in sludge were identified, and their fate in wastewater treatment processes was assessed. About half of priority substances of WFD were found at concentrations higher than 0.1 µg/L in wastewater. For 26 substances, potential non-compliance with Environmental Quality Standard of Water Framework Directive has been identified in treated wastewater, depending on river flow. Main concerns are for Cd, DEHP, diuron, alkylphenols, and chloroform. Emerging substances of particular concern are by-products, organic chemicals (e.g. triclosan, benzothiazole) and pharmaceuticals (e.g. ketoprofen, diclofenac, sulfamethoxazole, carbamazepine). About 80% of the load of micropollutants was removed by conventional activated sludge plants, but about two-thirds of removed substances were mainly transferred to sludge.

Polar organic chemical integrative samplers as an effective tool for chemical monitoring of surface waters - Results from one-year monitoring in France.

In an effort to support European Union Water Framework Directive goals, we have set up a national demonstrator project to identify the advantages and limitations of passive samplers for regulatory monitoring of polar contaminants in surface waters. Here we carried out successive 14 day-deployments of polar organic chemical integrative samplers (POCIS) for one year at three sites. In parallel, we used the passive sampler deployment/retrieval operations to collect spot water samples for comparative analysis. We observed that frequency of quantification was significantly higher in POCIS than spot samples for 29 contaminants, similar for 15, and lower for one, because POCIS lowered the limits of quantification for most contaminants (median value factor of 11). We built a database of sampling rates (Rs) according to quality indices to convert concentrations in POCIS to concentrations in water (23 contaminants with a high-quality median Rs value, 20 with an approximate Rs and two with no usable Rs). Several phenomena were observed over one-year monitoring period. For example, after a flood episode, dilution phenomenon in rivers is correctly observed by using POCIS sampling whereas significant concentration increased due to soil leaching is observed with both passive and spot sampling. Cases of episodic contamination that were missed by spot sampling were observed with POCIS as it was able to capture contamination of short duration but sufficient intensity. Contamination by pharmaceuticals was found to come from wastewater treatment plant discharges and showed relatively little variation over the course of the year in both POCIS and spot samples. POCIS enables more reliable annual monitoring of pesticide and pharmaceutical contamination than spot sampling. Furthermore, POCIS also improves the environmental quality standards based assessment of chemical status and on annual average concentrations compared to spot sampling. This study demonstrates the value and practicability of POCIS-based chemical monitoring for use in regulatory control networks.

On-site evaluation of the removal of 100 micro-pollutants through advanced wastewater treatment processes for reuse applications.

The next challenge of wastewater treatment is to reliably remove micro-pollutants at the microgram per litre range in order to meet reuse applications and contribute to reach the good status of the water bodies. A hundred priority and relevant emerging substances were measured to evaluate at full-scale the removal efficiencies of seven advanced treatment lines (one membrane bioreactor process and six tertiary treatment lines) that were designed for reuse applications. To reliably compare the processes, specific procedures for micro-pollutants were applied for sampling, analysis and calculation of removal efficiencies. The membrane bioreactor process allowed to upgrade the removal efficiencies of about 20% of the substances measured, especially those that were partially degraded during conventional processes. Conventional tertiary processes like high rate clarification, sand filtration and polishing pond achieved significant removal for some micro-pollutants, especially for adsorbable substances. Advanced tertiary processes, like ozonation, activated carbon and reverse osmosis were all very efficient to complete the removal of polar pesticides and pharmaceuticals; metals and less polar substances were better retained by reverse osmosis.

Limiting the emissions of micro-pollutants: what efficiency can we expect from wastewater treatment plants?

The next challenge of wastewater treatment is to reliably remove micro-pollutants at the microgram per litre range in order to meet the environmental quality standards set by new regulations like the Water Framework Directive. The present work assessed the efficiency of different types of primary, secondary and tertiary processes for the removal of more than 100 priority substances and other relevant emerging pollutants through on-site mass balances over 19 municipal wastewater treatment lines. Secondary biological processes proved to be in average 30% more efficient than primary settling processes. The activated sludge (AS) process led to a significant reduction of pollution loads (more than 50% removal for 70% of the substances detected). Biofilm processes led to equivalent removal efficiencies compared to AS, except for some pharmaceuticals. The membrane bioreactor (MBR) process allowed to upgrade removal efficiencies of some substances only partially degraded during conventional AS processes. Preliminary tertiary processes like tertiary settling and sand filtration could achieve significant removal for adsorbable substances. Advanced tertiary processes, like ozonation, activated carbon and reverse osmosis were all very efficient (close to 100%) to complete the removal of polar pesticides and pharmaceuticals; less polar substances being better retained by reverse osmosis.

Ozonation of 47 organic micropollutants in secondary treated municipal effluents: Direct and indirect kinetic reaction rates and modelling.

Micropollutants like pharmaceuticals, hormones and pesticides are still found in treated municipal wastewater. An effective way to degrade micropollutants is to use oxidants such as ozone or hydroxyl radicals. We designed an innovative experimental protocol combining batch experiments and a study of a full-scale WWTP to understand and predict the removal via ozonation of typical micropollutants present in secondary treated effluents. First, the direct and indirect ozonation of 47 organic micropollutants was scrutinized, then a model was developed and calibrated to simulate the ozone transfers and the oxidation of the selected micropollutants. The kinetic rate constants between micropollutants and ozone or hydroxyl radicals (OH●) were determined for 47 micropollutants found in secondary treated effluent. We classified the micropollutants into low- (kO3 between 1.50 and 4.47 × 102 L mol-1. s-1), medium- (kO3 between 1.31 × 103 and 4.92 × 103 L mol-1. s-1) and high-oxidizable groups (kO3 between 9.44 × 104 and 8.18 × 106 L mol-1. s-1) according to their reactivity with ozone, and identified the major degradation pathways for all 47 micropollutants. Micropolluants of the low- and medium-oxidizable groups were largely eliminated by the indirect pathway, at 96% and 84% on average, respectively. In contrast, micropollutants of high-oxidizable group were largely eliminated by the direct pathway, at 98% on average. The model successfully simulated the direct and indirect ozonation of the 47 micropollutants in batch experiments and confirmed the predominant pathways for each group. Finally, the model was applied to the full-scale ozonation process operated at an ozone dose ranging from 0.5 to 1.6 gO3. gDOC-1. The model was found to reliably simulate the ozonation-process removal efficiencies for 4 micropollutants (imidacloprid, fenofibric acid, metronidazole and ketoprofen).

To what extent can the biogeochemical cycling of mercury modulate the measurement of dissolved mercury in surface freshwaters by passive sampling?

Mercury (Hg) is a pollutant of global concern owing to its great toxicity even at very low concentrations. Its toxicity depends on its chemical forms evidencing the importance to study its speciation. Dissolved Hg (Hg(d)) and methylmercury (MeHg(d)) monitoring in surface freshwaters represents a great challenge because of their very low concentrations and substantial temporal variability at different timescales. The Hg(d) temporal variability depends on the environmental conditions such as the hydrology, water temperature, redox potential (Eh), and solar photo cycle. Passive samplers represent an alternative to improve the assessment of Hg(d) and MeHg(d) concentrations in surface freshwaters by integrating their temporal variability. An original sampling strategy was designed to assess the relevance of 3-mercaptopropyl DGT (Diffusive Gradient in Thin films) to integrate in situ the temporal variations of labile Hg (Hg(DGT)) and MeHg (MeHg(DGT)) concentrations. This strategy was implemented on two rivers to study the dynamics of Hg(d), Hg(DGT), MeHg(d) and MeHg(DGT) at diurnal and annual timescales. We evidenced that Hg(DGT) and MeHg(DGT) concentrations were generally consistent with discrete sampling measurements of Hg(d) and MeHg(d) in dynamic surface freshwaters. However, Hg(DGT) concentrations were overestimated (2-16 times higher) in case of low flow or low water depth, low suspended particulate matter (SPM) concentrations and elevated daily photoperiod. The most probable hypothesis is that such conditions promoted Hg0 production, and resulted in Hg0 uptake by DGT. Thus, attention should be paid when interpreting Hg(DGT) concentrations in surface freshwaters in environmental conditions that could promote Hg0 production.

Influence of water depth and season on the photodegradation of micropollutants in a free-water surface constructed wetland receiving treated wastewater.

Micropollutants such as pharmaceutical products and pesticides are still present in treated wastewater. Several of these compounds are photoactive, either by direct or indirect photodegradation. An innovative on-site experimental protocol was designed to investigate the contribution of photodegradation processes to eliminate micropolluants in constructed wetland (CW). The solar photodegradation of 23 organic micropollutants was studied using in situ photoreactors at different depths. A CW-photodegradation model was designed and calibrated to further scrutinize the contribution of direct and indirect photodegradation processes in the elimination of micropollutants. The results show that photodegradation is most effective in the first 10 cm of the water column. A classification of micropollutants in 3 groups was developed to characterize their photodegradation. A significant increase of the half-life by direct photodegradation was observed in winter compared to summer due to a lower light intensity in winter. On the opposite, for direct + indirect photodegradation, no significant difference was observed between seasons. The decrease in light intensity in winter was compensated by higher nitrates concentration which promoted the formation of hydroxyl radicals and increased indirect photodegradation. The CW-photodegradation model successfully simulated the measured concentrations for direct and indirect photodegradation for 23 micropolluants. Nonetheless, it overestimated the indirect photodegradation with hydroxyl radicals when using default parameter values derived for surface waters. Hence, the consumption of hydroxyl radicals was increased by a factor of 20 for treated water. This model highlighted the predominance of direct photodegradation in the elimination of all micropollutants, except sotalol for the winter campaign.

Removal efficiency of pharmaceuticals and personal care products with varying wastewater treatment processes and operating conditions - conception of a database and first results.

We created a database in order to quantitatively assess the occurrence and removal efficiency of PPCPs in WWTPs. From 113 scientific publications, we compiled 5887 data on the concentrations and loads of PPCPs in WWTP influents and effluents, and on their removal efficiency. The first outputs of our database include: (1) a list of the most frequently studied molecules, their frequency of detection, their mean concentration and removal in liquid influent and effluent; (2) a comparison of the removal efficiency for different WWTP processes; (3) a study of the influence of the operating conditions (sludge and hydraulic retention times).

Sampling of suspended particulate matter using particle traps in the Rhône River: Relevance and representativeness for the monitoring of contaminants.

Monitoring hydrophobic contaminants in surface freshwaters requires measuring contaminant concentrations in the particulate fraction (sediment or suspended particulate matter, SPM) of the water column. Particle traps (PTs) have been recently developed to sample SPM as cost-efficient, easy to operate and time-integrative tools. But the representativeness of SPM collected with PTs is not fully understood, notably in terms of grain size distribution and particulate organic carbon (POC) content, which could both skew particulate contaminant concentrations. The aim of this study was to evaluate the representativeness of SPM characteristics (i.e. grain size distribution and POC content) and associated contaminants (i.e. polychlorinated biphenyls, PCBs; mercury, Hg) in samples collected in a large river using PTs for differing hydrological conditions. Samples collected using PTs (n = 74) were compared with samples collected during the same time period by continuous flow centrifugation (CFC). The grain size distribution of PT samples shifted with increasing water discharge: the proportion of very fine silts (2-6 µm) decreased while that of coarse silts (27-74 µm) increased. Regardless of water discharge, POC contents were different likely due to integration by PT of high POC-content phytoplankton blooms or low POC-content flood events. Differences in PCBs and Hg concentrations were usually within the range of analytical uncertainties and could not be related to grain size or POC content shifts. Occasional Hg-enriched inputs may have led to higher Hg concentrations in a few PT samples (n = 4) which highlights the time-integrative capacity of the PTs. The differences of annual Hg and PCB fluxes calculated either from PT samples or CFC samples were generally below 20%. Despite some inherent limitations (e.g. grain size distribution bias), our findings suggest that PT sampling is a valuable technique to assess reliable spatial and temporal trends of particulate contaminants such as PCBs and Hg within a river monitoring network.

Metal measurement in aquatic environments by passive sampling methods: Lessons learning from an in situ intercomparison exercise.

Passive sampling devices (PS) are widely used for pollutant monitoring in water, but estimation of measurement uncertainties by PS has seldom been undertaken. The aim of this work was to identify key parameters governing PS measurements of metals and their dispersion. We report the results of an in situ intercomparison exercise on diffusive gradient in thin films (DGT) in surface waters. Interlaboratory uncertainties of time-weighted average (TWA) concentrations were satisfactory (from 28% to 112%) given the number of participating laboratories (10) and ultra-trace metal concentrations involved. Data dispersion of TWA concentrations was mainly explained by uncertainties generated during DGT handling and analytical procedure steps. We highlight that DGT handling is critical for metals such as Cd, Cr and Zn, implying that DGT assembly/dismantling should be performed in very clean conditions. Using a unique dataset, we demonstrated that DGT markedly lowered the LOQ in comparison to spot sampling and stressed the need for accurate data calculation.

Intrahaplotype polymorphism at the Brassica S locus.

The S locus receptor kinase and the S locus glycoproteins are encoded by genes located at the S locus, which controls the self-incompatibility response in Brassica. In class II self-incompatibility haplotypes, S locus glycoproteins can be encoded by two different genes, SLGA and SLGB. In this study, we analyzed the sequences of these genes in several independently isolated plants, all of which carry the same S haplotype (S(2)). Two groups of S(2) haplotypes could be distinguished depending on whether SRK was associated with SLGA or SLGB. Surprisingly, SRK alleles from the two groups could be distinguished at the sequence level, suggesting that recombination rarely occurs between haplotypes of the two groups. An analysis of the distribution of polymorphisms along the S domain of SRK showed that hypervariable domains I and II tend to be conserved within haplotypes but to be highly variable between haplotypes. This is consistent with these domains playing a role in the determination of haplotype specificity.

Lab-scale experimental strategy for determining micropollutant partition coefficient and biodegradation constants in activated sludge.

The nitrifying/denitrifying activated sludge process removes several micropollutants from wastewater by sorption onto sludge and/or biodegradation. The objective of this paper is to propose and evaluate a lab-scale experimental strategy for the determination of partition coefficient and biodegradation constant for micropollutant with an objective of modelling their removal. Four pharmaceutical compounds (ibuprofen, atenolol, diclofenac and fluoxetine) covering a wide hydrophobicity range (log Kow from 0.16 to 4.51) were chosen. Dissolved and particulate concentrations were monitored for 4 days, inside two reactors working under aerobic and anoxic conditions, and under different substrate feed conditions (biodegradable carbon and nitrogen). We determined the mechanisms responsible for the removal of the target compounds: (i) ibuprofen was biodegraded, mainly under aerobic conditions by cometabolism with biodegradable carbon, whereas anoxic conditions suppressed biodegradation; (ii) atenolol was biodegraded under both aerobic and anoxic conditions (with a higher biodegradation rate under aerobic conditions), and cometabolism with biodegradable carbon was the main mechanism; (iii) diclofenac and fluoxetine were removed by sorption only. Finally, the abilities of our strategy were evaluated by testing the suitability of the parameters for simulating effluent concentrations and removal efficiency at a full-scale plant.

Effect of the various parameters governing solid-phase microextraction for the trace-determination of pesticides in water.

The parameters governing solid-phase microextraction (SPME) are investigated, with emphasis on the determination of the partition coefficients, K, and their use to predict the selection of a fibre, depending on the respective characteristics of the fibres and the analytes. Film thickness and stability of the compounds can interfere with the determination of K values. The time profile curves were determined for twelve pesticides having a wide range of water solubilities and polarities and using four fibres (polydimethylsiloxane, polydimethylsiloxane-divinylbenzene, Carbowax-divinylbenzene and polyacrylate). Although the affinity order was different for the four coatings, no correlation was found between the respective characteristics of the fibres and solutes. The two fibres containing divinylbenzene were shown to have the highest affinities and the polydimethylsiloxane had the lowest affinity. The polyacrylate fibre which is the more polar commercial fibre did not provide the highest affinities for the more polar and water-soluble analytes. The important parameters for quantitative analysis have been evaluated. The calibration curves were similar when one analyte of interest was present on its own in a drinking water sample, or when eleven other pesticides were present at the same concentration or when much higher concentrations of other analytes were present in the sample. Linearity was obtained over a wide range of concentrations in drinking water samples. Detection limits are in agreement with European regulatory levels in drinking water for most of the analytes using solid-phase microextraction-gas chromatography-nitrogen-phosphorus detection (SPME-GC-NPD). In contaminated surface water samples, the chromatograms are relatively clean and most of the compounds can be detected at levels lower than 0.5 microgram/l.

Optimization, validation and comparison of various extraction techniques for the trace determination of polycyclic aromatic hydrocarbons in sewage sludges by liquid chromatography coupled to diode-array and fluorescence detection.

There is a need for a better characterization of sludges from wastewater treatment plants which are destined to be spread on agricultural lands. Inorganic pollutants are regularly controlled but organic pollutants have received few attention up to now. On this paper, we have been interested on the analysis of the 16 polycyclic aromatic hydrocarbons (PAHs) listed in the US Environmental Protection Agency (US EPA) priority list and more particularly of the six PAHs listed in the European community list (fluoranthene, benzo[b and k]fluoranthene, benzo[a]pyrene, benzo[ghi]perylene, indeno[1,2,3-cd]pyrene). The analysis step consists on liquid chromatography with both fluorescence and UV detections as described in the EPA Method 8310. As for the extraction step, several techniques such as supercritical fluid extraction, pressurized liquid extraction, focused microwave extraction in open vessels, Soxhlet and ultrasonic extractions are compared after optimization of the experimental conditions (solvent nature and quantity, temperature, pressure, duration, ... ) and validation with certified sludges. When optimized, these five extraction techniques are as much efficient with similar relative standard deviation. Whatever the extraction techniques used, the whole analysis protocol permits to quantify PAHs in the range of 0.09 to 0.9 mg/kg of dried sludges.

Optimization and validation of solvent and supercritical-fluid extractions for the trace-determination of polycyclic aromatic hydrocarbons in sewage sludges by liquid chromatography coupled to diode-array and fluorescence detection.

There is a need for a better characterization of sludges from wastewater treatment plants which are destined to be spread on agricultural land. Inorganic pollutants are regularly controlled, but organic pollutants have received little attention up to now. The main problem for trace analysis of organic pollutants comes from the complexity of the various matrices of sludges, which depends on their origins. Therefore, methods described for soils and sediments cannot be directly applied to sludges which contain high amount of lipids. This paper provides a method for trace-determination of polycyclic aromatic hydrocarbons in the range of mg/kg of dried sludge including an extraction step, and an analysis step by liquid chromatography with fluorescence detection for sensitive quantification and UV-diode-array detection for confirmation. The extraction step was optimized by a selection of the solvent used for both Soxhlet and supercritical-fluid extraction and by setting the experimental conditions (temperature, pressure, modifier, etc.) used for SFE. Extraction recoveries were found similar and quantitative for the two procedures. However supercritical-fluid extraction appears to be a good alternative to Soxhlet extraction because of the consumption of less time and solvent. Detection limits were obtained in the range of 0.1-1 mg/kg of dried sludges, with possible confirmation by UV spectra. The whole method (extraction/quantification/confirmation) was validated using sludges which have been certified by the Community Bureau of Reference from Brussels (CRM No. 088). Application to the determination of PAHs in urban sludges is presented.

Selective immunoclean-up followed by liquid or gas chromatography for the monitoring of polycyclic aromatic hydrocarbons in urban waste water and sewage sludges used for soil amendment.

A selective clean-up procedure using immunoaffinity solid-phase extraction was applied for the trace-level determination of polycyclic aromatic hydrocarbons (PAHs) in urban waste water and sewage sludges used for soil amendment. Anti-pyrene antibodies have been immobilized on a silica-based sorbent and the cross-reactivity of the antibodies towards structurally related compounds were allowed to extract the whole class of priority PAHs. The selectivity of the antibodies provided clean extracts from sludges and, therefore, the identification and quantification were shown to be easier using either liquid chromatography (LC) with UV diode array and fluorescence detection in series or gas chromatography-mass spectrometry (GC-MS), although some loss of up to 50% was observed for the clean-up. The identification of the PAHs by matching of UV and MS spectra was greatly improved. The procedure, including immunoclean-up and LC coupled to diode array and fluorescence detection, was validated using certified reference materials with native PAHs of concentrations in the range of 0.57-2.16 mg/kg (dry sludges).

Molecular evolution of the s locus controlling mating in the brassicaceae.

Flowering plants possess self-incompatibility (SI) mechanisms that promote outbreeding and thereby increase their genetic diversity. In the self-incompatible Brassicaceae, recognition and rejection of self-pollen is based on a receptor-ligand interaction between male and female SI determinants. A transmembrane receptor kinase (S locus Receptor Kinase, SRK) determines the SI specificity in stigmatic cells, whereas a pollen coat-localized ligand (S locus Cysteine-Rich, SCR) determines the SI specificity in pollen. During recent years, major advances have been made in the understanding of the molecular basis of self-pollen recognition by stigmatic cells. In this review, we will focus on evolutionary aspects of the SI system in Brassicaceae. We will describe how the study of the molecular aspect of SI, not only in the historical Brassica model but also in Arabidopsis species, has contributed to highlight certain aspects of evolution of SI in the Brassicaceae.

Survival tests with Chironomus riparius exposed to spiked sediments can profit from DEBtox model.

DEBtox model is a biologically based model used to analyse aquatic toxicity data (The analysis of aquatic toxicity data, VU University Press, Amsterdam, The Netherlands, 1996, 149pp.). To date, it has not been used to analyse sediment survival tests, mainly because this would require daily counting of survivors, which is difficult for benthic organisms. In the present study, we adapted survival toxicity tests with the midge Chironomus riparius to permit survival data analysis with DEBtox. To validate the adaptation proposed, we exposed organisms to two chemicals, copper and methiocarb. We exposed larvae of second, third and fourth instar to different concentrations of the tested compounds and two different diets to assess the influence of diet and instar on DEBtox parameter estimates. Daily counting of organisms did not affect survival and did not lead to much more effort when compared to usual tests. Moreover, the analysis profited much from use of the DEBtox model. It was possible, with only survival data to estimate and validate the kinetics of the compounds, to predict survival during the recovery of exposed organisms and to assess the influence of food availability on toxicity. Food availability did not influence methiocarb toxicity, but copper was more toxic to food-limited organisms when a threshold concentration was exceeded. Comparison of parameters estimate also helped in understanding the differences in toxicity responses between instars. For the two compounds we studied, the difference was entirely explained by differences in threshold values.

Impact of wastewater treatment plants on receiving surface waters and a tentative risk evaluation: the case of estrogens and beta blockers.

Five estrogenic hormones (unconjugated + conjugated fractions) and 10 beta blockers were analyzed in three wastewater treatment plant (WWTP) effluents and receiving river waters in the area of Lyon, France. In the different samples, only two estrogens were quantified: estrone and estriol. Some beta blockers, such as atenolol, acebutolol, and sotalol, were almost always quantified, but others, e.g., betaxolol, nadolol, and oxprenolol were rarely quantified. Concentrations measured in river waters were in the nanogram per liter range for estrogens and between 0.3 and 210 ng/L for beta blockers depending on the substance and the distance from the WWTP outfall. The impact of the WWTP on the receiving rivers was studied and showed a clear increase in concentrations near the WWTP outfall. For estrogens, the persistence in surface waters was not evaluated given the low concentrations levels (around 1 ng/L). For beta blockers, concentrations measured downstream of the WWTP outfall were up to 16 times higher than those measured upstream. Also, the persistence of metoprolol, nadolol, and propranolol was noted even 2 km downstream of the WWTP outfall. The comparison of beta blocker fingerprints in the samples collected in effluent and in the river also showed the impact of WWTP outfall on surface waters. Finally, a tentative environmental risk evaluation was performed on 15 sites by calculating the ratio of receiving water concentrations to predicted non-effect concentrations (PNEC). For estrogens, a total PNEC of 5 ng/L was considered and these substances were not linked to any potential environmental risk (only one site showed an environmental risk ratio above 1). Unfortunately, few PNECs are available and risk evaluation was only possible for 4 of the 10 beta blockers studied: acebutolol, atenolol, metoprolol, and propranolol. Only propranolol presented a ratio near or above 1, showing a possible environmental risk for 4 receiving waters out of 15.