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This study aimed to evaluate treatment performance and membrane fouling of a lab-scale Sponge-MBR under the added ciprofloxacin (CIP) dosages (20; 50; 100 and 200 µg L−1) treating hospital wastewater. The results showed that Sponge-MBR exhibited effective removal of COD (94–98%) during the operation period despite increment of CIP concentrations from 20 to 200 µg L−1. The applied CIP dosage of 200 µg L−1 caused an inhibition of microorganisms in sponges, i.e. significant reduction of the attached biomass and a decrease in the size of suspended flocs. Moreover, this led to deteriorating the denitrification rate to 3–12% compared to 35% at the other lower CIP dosages. Importantly, Sponge-MBR reinforced the stability of CIP removal at various added CIP dosages (permeate of below 13 µg L−1). Additionally, the fouling rate at CIP dosage of 200 µg L−1 was 30.6 times lower compared to the control condition (no added CIP dosage).

Harmful algal blooms (HABs) of cyanobacterial origin have the potential to generate hundreds of secondary metabolites referred to as cyanotoxins. Freshwater resources have been threatened by HABs and an increase of these episodes is of major concern worldwide for risk management and ecosystem impacts. To meet the need to rapidly screen a wide range of cyanotoxins, a multi-toxin method based on on-line solid-phase extraction ultra-high performance liquid chromatography high-resolution mass spectrometry (SPE-UHPLC-HRMS) was developed and validated. This method enabled high-throughput screening of cylindrospermopsin, anatoxin-a, homoanatoxin-a, anabaenopeptins A and B, and twelve microcystins (-RR, [Asp3]-RR, -YR, -HtyR, -LR, [Asp3]-LR, -HilR, -WR, -LA, -LY, -LW and -LF) in recreational lake waters. Extraction and separation were achieved in 8 minutes, with limits of detection between 8 and 53 ng L−1. The method offered suitable precision for environmental samples (generally

The proliferation of harmful cyanobacterial algal blooms is of concern due to the associated release of toxins affecting ecosystems and human health. The paralytic shellfish poison saxitoxin (STX) is a small polar alkaloid that can occur in inland and marine aquatic environments. Here, we optimized a fast and sensitive analytical method for the determination of STX, neosaxitoxin (NeoSTX), and their decarbamoyl analogues in surface waters. The method involves a simple filtration, addition of isotope-labelled internal standard (ILIS), and analysis by on-line solid-phase extraction coupled to hydrophilic interaction liquid chromatography high-resolution mass spectrometry (on-line SPE-HILIC-HRMS). Except glass fiber filters, other tested materials (e.g., nylon, nitrocellulose) provided suitable filtration performance. Time-dependent adsorptive losses occurred during the LC-MS batch sequence if glass autosampler vials were used, while no such effect was observed for polypropylene autosampler vials. Matrix effects were evaluated for 4 different quantification scenarios, including external vs. internal curves and neat reagent water vs. matrix-matched curves. Matrix-matched calibration with ILIS correction (NeoSTX

International audience; Sedimentological and geochemical data were obtained for bed sediments from a tropical estuary environment in Vietnam in October 2014, January 2016, and November 2016. The data include grain-size distribution, percentage of clay, silt and sand, percentage of organic matter, concentration of total particulate phosphorus (TPP), concentration of particulate inorganic phosphorus (PIP), concentration of particulate organic phosphorus (POP), percentage of total nitrogen (TN), percentage of total carbon (TC), trace metals concentrations (V, Cr, Co, Ni, Cu, Zn, As, Mo, Cd, Pb) and major elements (Al, Fe, Mn). Geochemical indexes (Enrichment factor EF and Geo-accumulation Index I-geo) and sediment quality guideline (mean Effect Range Median quotients) were calculated.

Cyanotoxins, as secondary metabolites of cyanobacteria, are highly toxic to humans, animals and plants. Cyanobacterial blooms are 'hot spots' for cyanotoxin production, but we hypothesized that cyanotoxins will be present in multiple ecological compartments of agricultural watersheds. We detected cyanotoxins in the vadose zone (soil and drainage water from the soil profile) and in groundwater used as a drinking water source from agricultural watersheds. Cyanotoxins detection was confirmed with enzyme-linked immunosorbent assay kits and ultra-high liquid chromatography with tandem mass spectrometry. This work confirms that cyanotoxins exist outside of freshwater lakes, based on detection of microcystins in the vadose zone and in drinking water sourced from groundwater in agricultural watersheds. This suggests that cyanotoxins may be transferred from cyanobacterial blooms in lakes to groundwater through normal hydrologic processes. Public health authorities should be alerted to cyanotoxins in drinking water supplies and proper monitoring and treatment protocols should be implemented to protect citizens from this potential health hazard.

Harmful algal blooms of cyanobacteria (CyanoHABs) can lead to the release of potent toxins that can seriously affect ecosystem integrity. Some freshwater watersheds are particularly at risk considering the threats to already imperiled wildlife. The consumption of tainted drinking water and contaminated food also raises concerns for human health. In the present study, a pilot survey was conducted in the riverine ecosystem of the Pike River Ecological Reserve (QC, Canada) near Missisquoi Bay, Lake Champlain. We examined the occurrence of multiclass cyanotoxins including 12 microcystins, anatoxins, cylindrospermopsin (CYN), anabaenopeptins (AP-A, AP-B), and cyanopeptolin-A in surface waters and wild-caught fish during the summer 2018. Out of the 18 targeted cyanotoxins, 14 were detected in bloom-impacted surface water samples; toxins peaked during early-mid September with the highest concentrations for MC-LR (3.8 μg L−1) and MC-RR (2.9 μg L−1). Among the 71 field-collected fish from 10 species, 30% had positive detections to at least one cyanotoxin. In positive samples, concentration ranges in fish muscle were as follows for summed microcystins (∑MCs: 0.16–9.2 μg kg−1), CYN (46–75 μg kg−1), AP-A (1.1–5.4 μg kg−1), and AP-B (0.12–5.0 μg kg−1). To the best of our knowledge, this is one the first reports of anabaenopeptins occurrence in wildlife. The maximum ∑MCs in fish was 1.15-fold higher than the World Health Organization (WHO) daily intake recommendation for adults and nearly equated the derived value for young children. The concentration of CYN was also about 3-fold higher than the limit derived from the human health guideline values.

The neurotoxin β-N-methylamino-L-alanine (BMAA), suspected to trigger neurodegenerative diseases, can be produced during cyanobacterial bloom events and subsequently affect ecosystems and water sources. Some of its isomers including β-amino-N-methylalanine (BAMA), N-(2-aminoethyl) glycine (AEG), and 2,4-diaminobutyric acid (DAB) may show different toxicities than BMAA. Here, we set out to provide a fast and sensitive method for the monitoring of AEG, BAMA, DAB and BMAA in surface waters. A procedure based on aqueous derivatization with 9-fluorenylmethyl chloroformate (FMOC-Cl) was investigated for this purpose. Under optimized conditions, a small aqueous sample aliquot (5 mL) was spiked with BMAA-d3 internal standard, subjected to FMOC-Cl derivatization, centrifuged, and analyzed. The high-throughput instrumental method (10 min per sample) involved on-line pre-concentration and desalting coupled to ultra-high-performance liquid chromatography high-resolution mass spectrometry (UHPLC-HRMS). Chromatographic gradient and mobile phases were adjusted to obtain suitable separation of the 4 isomers. The method limits of detection were in the range of 2-5 ng L-1. In-matrix validation parameters including linearity range, accuracy, precision, and matrix effects were assessed. The method was applied to surface water samples (n = 82) collected at a large spatial scale in lakes and rivers in Canada. DAB was found in >70% of samples at variable concentrations (

Reproducible analytical procedures and rigorous quality control are imperative for an accurate monitoring of cyanobacterial toxins in environmental water samples. In this study, the short-term and long-term storage stability of diverse cyanotoxins (anatoxins, cylindrospermopsin, anabaenopeptins, and 12 microcystins) was evaluated in water samples, under different scenarios. Transport controls were performed at three monitoring sites in spiked ultrapure water and lake water to investigate short-term stability issues. Medium-term storage stability was evaluated for up to 14–28 days in ultrapure water, chlorine-treated drinking water (amended with reductant), and surface water (filtered and unfiltered) stored at different temperatures (20 °C, 4 °C, and –20 °C). Substantial decreases of cylindrospermopsin and anabaenopeptins were observed in tap water (20 °C) and unfiltered surface water (20 °C or 4 °C). Regardless of matrix type, cyanotoxin recoveries generally remained within an 80–120% range when the water samples were kept frozen. After a prolonged storage duration of 365 days at –20 °C, most cyanotoxins experienced decreases in the range of 10–20%. The notable exception was for the tryptophan-containing MC-LW and MC-WR, with more substantial variations (30% to 50% decrease) and conversion to N-formylkynurenine analogs. Reanalysis of field-collected surface waters after long-term storage at –20 °C also indicated significantly decreasing trends of cyanotoxins (between 6% and 23% decrease). In view of the above, short sample hold times should be favored as recommended in EPA methods.

This work presents the optimization of analytical procedures for the determination of two antibiotics, oxolinic acid (OA) and flumequine (FL), in bed sediment, river water, and soil samples. Three extraction methods (microwave-assisted extraction (MAE), ultrasonication, and reflux) were tested, and the highest recoveries were obtained with MAE (94 ± 3% and 95 ± 3% for OA and FL, respectively). A solid-phase extraction (SPE) clean-up step was optimized by comparing two polymeric sorbents: Oasis HLB and Oasis MAX. The final extracts were analyzed by liquid chromatography with fluorimetric detection. Limits of detection (LOD) obtained for OA and FL in soil and sediment ranged from 0.3 to 0.5 µg kg−1. Meanwhile, a novel SPE procedure was also implemented for OA and FL determination in river water samples. It also relied on the use of Oasis MAX, and recovery rates were in the range 90–94%; LODs were 2 ng L−1 for both OA and FL. These methods were applied for the analysis of samples taken in the Seine R...

Freshwater and marine seafood products purchased in Montreal, Canada, were screened for diverse veterinary drug residues including sulfonamides and potentiators, macrolides, lincosamides, nitrofurans, nitroimidazoles, amphenicols, quinolones and fluoroquinolones, one triphenylmethane dye and its leuco-metabolite, and tetracyclines. QuEChERS extraction ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) was validated in three model matrices (fatty fish, lean fish, and shrimp edible meat). Method detection limits were in the range of 0.002–3 μg/kg, and the accuracy of matrix-matched extracted calibrants was generally within acceptance criteria. The aquaculture or wild-caught samples of pangasius (basa), cod, salmon, sole, tilapia, trout, white shrimp and giant tiger prawn originated from Canada, China, India, Southeast Asia (Indonesia, Thailand, Vietnam), and other regions worldwide. Overall, 38 % of the tested fish and shrimp samples had detectable residues of at least one veterinary drug or metabolite, and 25 % were not compliant to Canadian guidelines. Leucomalachite green was detected across various sample types (detection frequency: 13 %; maximum: 0.9 μg/kg). Other detected compounds (2–11 % of samples) included tetracycline (maximum: 36 μg/kg), 4-epi-oxytetracycline (18 μg/kg), oxytetracycline (13 μg/kg), metronidazole (13 μg/kg), sulfamethazine (4.8 μg/kg), sulfamethoxazole (4.2 μg/kg), trimethoprim (0.59 μg/kg), florfenicol (0.27 μg/kg), flumequine (0.21 μg/kg), enrofloxacin (1.6 μg/kg), and ofloxacin (0.52 μg/kg).

Microbiological water quality is traditionally assessed using culture-based enumeration of faecal indicator bacteria such as Escherichia coli. Despite their relative ease of use, these methods require a minimal 18-24 h-incubation step before the results are obtained. This study aimed to assess the suitability of an autonomous online fluorescence-based technology measuring β-glucuronidase (GLUC) activity for rapid near-real time monitoring of E. coli in water. The analytical precision was determined and compared to an automated microbial detection system, two culture-based assays and quantitative real-time PCR (qPCR). Using replicate measurements of grab samples containing E. coli concentrations between 50 and 2330 CFU.100 mL−1, the autonomous GLUC activity measurement technology displayed an average coefficient of variation (CV) of less than 5% that was 4–8-fold lower than other methods tested. Comparable precision was observed during online in situ monitoring of GLUC activity at a drinking water intake using three independent instruments. GLUC activity measurements were not affected by sewage or sediments at concentrations likely to be encountered during long-term monitoring. Furthermore, significant (p < 0.05) correlations were obtained between GLUC activity and the other assays including defined substrate technology (r = 0.77), membrane filtration (r = 0.73), qPCR (r = 0.55) and the automated microbial detection system (r = 0.50). This study is the first to thoroughly compare the analytical performance of rapid automated detection technologies to established culture and molecular-based methods. Results show that further research is required to correlate GLUC activity to the presence of viable E. coli as measured in terms of CFU.100 mL−1. This would allow the use of autonomous online GLUC activity measurements for rapid E. coli monitoring in water supplies used for drinking water production and recreation., SCOPUS: ar.j, info:eu-repo/semantics/published

In Vietnam, intensive shrimp farms heavily rely on a wide variety of antibiotics (ABs) to treat animals or prevent disease outbreak. Potential for the emergence of multi-resistant bacteria is high, with the concomitant contamination of adjacent natural aquatic habitats used for irrigation and drinking water, impairing in turn human health system. In the present study, quantification of AB multi-resistant bac- teria was carried out in water and sediment samples from effluent channels connecting a shrimp farming area to the Vam Co River (Long An Province, Vietnam). Bacterial strains, e.g. Klebsiella pneumoniae and Aeromonas hydrophila, showing multi-resistance traits were isolated. Molecular biology analysis showed that these strains possessed from four to seven different AB resistance genes (ARGs) (e.g. sul1, sul2, qnrA, ermB, tetA, aac(6)lb, dfrA1, dfr12, dfrA5), conferring multidrug resistance capacity. Sequencing of plasmids present within these multi-resistant strains led to the identification of a total of forty-one resistance genes, targeting nine AB groups. qPCR analysis on the sul2 gene revealed the presence of high copy numbers in the effluent channel connecting to the Vam Co River. The results of the present study clearly indicated that multi-resistant bacteria present in intensive shrimp cultures may disseminate in the natural environment. This study offered a first insight in the impact of plasmid-born ARGs and the related pathogenic bacteria that could emerged due to inappropriate antibiotic utilization in South Vietnam.

International audience; The Mekong Delta, is home to 17 million inhabitants and faces numerous challenges relating to climate change, environmental degradation and water issues. In this study, we assess trace metals concentrations (Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Mo, Cd, Hg, Pb) in the water, suspended particulate matter and surface sediments of the Tien River, the Northern branch of the Mekong Delta, during both dry and rainy seasons. Metal concentrations in the dissolved and suspended particle phases remain in the low concentration range of the main Asian Tropical River. During transportation in the riverine part, we evidenced that V, Cr, Co, As and Pb are dominant in the particulate phase while Mo, Ni and Cu dominate in the dissolved fraction. In the salinity gradient, dissolved U, V, Mo exhibit conservative behaviour while Ni, Cu, As, Co and Cd showed additive behaviour suggesting desorption processes. In the surface sediment, metal concentrations are controlled by the particle-size, POC contents and Fe, Al and Mn e oxy(hydr)oxides. Calculated Enrichment Factor and Geoaccumulation Index evidenced As enrichment while the calculated mean effect range median quotients evidenced a low to medium ecotoxicological potential effects range in the surface sediments.

The transfer of 23 antibiotics from domestic and hospital sources was investigated in two elementary river watersheds receiving wastewater treatment plant (WWTP) discharges, in relation with the hydrological cycle and seasonal conditions. Antibiotic concentrations in the effluent of a WWTP treating wastewaters from both hospital and domestic sources (18-12 850 ng L-1) were far higher than those from domestic sources exclusively (3-550 ng L-1). In rivers, upstream of the WWTP discharges, fluoroquinolones only were found at low concentrations (≤10 ng L-1). Their presence might be explained by transfer from contaminated agricultural fields located on the river banks. Immediately downstream of the WWTP discharge, antibiotic occurrence increased strongly with mean concentrations up to 1210 ng L-1 for ofloxacin and 100% detection frequencies for vancomycin, sulfamethoxazole, trimethoprim and three fluoroquinolones. Dilution processes during high-flow periods led to concentrations 14 times lower than during low-flow periods. Downstream of the discharge, the antibiotic dissipation rate from the water column was higher for fluoroquinolones, in relation with their high sorption upon suspended matter and sediment. Only five antibiotics (vancomycin and four fluoroquinolones ciprofloxacin, norfloxacin, ofloxacin and enoxacin) were partly distributed (11%-36%) in the particulate phase. Downstream of the discharge, antibiotic contents in sediment ranged from 1700 to 3500 ng g-1 dry weight, fluoroquinolones accounting for 97% of the total.

Investigation of domestic and hospital effluents in a sewage system of an elementary watershed showed that antibiotics belonging to eight classes were present with concentrations ranging from

Hospital wastewater contains huge amounts of hazardous pollutants which are being discharged daily to environment with or without treatment. Antibiotics were among the important group of pharmaceuticals considered as a potential source of health risk for human and other living creatures. Although the investigations about the existence of antibiotics in hospital wastewater have gained concern for researchers in many countries, there is only one research conducted in Hanoi-Vietnam. Hence, in this study, investigations have been done to fulfill the requirement of real situation in Vietnam by accomplishing survey for 39 health care facilities in Ho Chi Minh City. As results, seven popular antibiotics were detected to exist in all samples such as sulfamethoxazole (2.5 ± 1.9 μg/L), norfloxacin (9.6 ± 9.8 μg/L), ciprofloxacin (5.3 ± 4.8 μg/L), ofloxacin (10.9 ± 8.1 μg/L), erythromycin (1.2 ± 1.2 μg/L), tetracycline (0.1 ± 0.0 μg/L), and trimethoprim (1.0 ± 0.9 μg/L). On the other hand, survey also showed that only 64% of health care facilities using conventional activate sludge (AS) processes in wastewater treatment plants (WWTPs). As a consequence, basic environmental factors (BOD5, COD, TSS, NH4 +-N, or total coliforms) were not effectively removed from the hospital wastewater due to problems relating to initial design or operational conditions. Therefore, 18% effluent samples of the surveyed WWTPs have exceeded the national standard limits (QCVN 28:2010, level B).

Antibiotic residues in the environment and their potential toxic effects have been considered as one of the emerging research area in the environmental field. Their continuous introduction in our environment may increase their negative impacts on human health. In this study, the eliminations of antibiotic such as Norfloxacin (NOR), Ciprofloxacin (CIP), Ofloxacin (OFL) and Sulfamethoxazole (SMZ) in wastewater of hospital were processed by membrane bioreactor (MBR) coupled with ozonation process. In particular, the MBR was applied for the antibiotic removals followed by ozonation process as a post-treatment stage to create an adequate integration to enhance removal efficiency. Achieved results after MBR treatment showed that the removal efficiency of NOR, CIP, OFL and SMZ were 90 ± 4.0% , 83 ± 13% , 81 ± 13 % and 39 ± 6%, respectivley. In addition, those antibiotic matters were continously removed by ozonation process with the removal efficiency of 87±9.0% , 83±1.0% , 81±2.3% and 66±2.3% for NOR, CIP, OFL and SMZ, respectively. In summary, antibiotics could be basically limited by the combination of MBR and ozonation before discharging in aquatic environment.

This study presents the development of an automated on-line solid phase extraction (SPE)-liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the determination of 23 antibiotics in environmental water samples. After optimisation of LC-MS/MS conditions, SPE parameters such as sorbent type, sample pH or sample volume were optimised. Antibiotic recoveries ranged from 64% to 98% and compared favourably with those achieved using off-line SPE. Limits of detection were in the range 0.5-13.7 ng L(-1). This on-line SPE-LC-MS/MS procedure was applied to the analysis of water samples taken in three rivers within the Seine River basin, near Paris (France). The obtained results revealed the occurrence of 12 antibiotics, including tylosin, erythromycin, tetracycline, amoxicillin, trimethoprim, sulfamethoxazole, oxolinic acid, flumequine, norfloxacin, ciprofloxacin, ofloxacin, and vancomycin (2-1435 ng L(-1)).

International audience; The Saigon River, Southern Vietnam, crosses one of the most dynamic developing Megacity in Southeast Asia: Ho Chi Minh City (HCMC). The increased economic, industrial, and domestic developments may affect the environmental quality of water and halieutic resources. In this study, we evaluated the seasonal (dry and wet seasons) biogeochemical state of the Saigon River during two snapshot campaigns conducted along the river basin upstream from HCMC; the Saigon River was characterized by slightly acidic (pH 5.7-7.7) and oxygen-depleted water (dissolved oxygen (DO), 0.36-5.18 mg l −1). Nutrients (N-NH 4 = 0.01-2.41, N-NO 3 = 0.14-2.72, and P-PO 4 =~0-0.42 mg l −1), DOC (2.2-8.0 mg l −1), POC, and trace metal(oid) (As, Cd, Cr, Cu, Zn, and Hg) concentrations were low showing a good quality of the upstream river. In the urban center area, DO dropped to 0.03 mg l −1 accompanied with a rise of nutrient concentrations (e.g., N-NH 4 , up to 17.7 mg l −1) likely originating from wastewater discharges. Trace metal concentrations also rose sharply (e.g., Cr and Hg rose up to 10-fold higher) in both water and sediments but remained under the World Health Organization (WHO) and Vietnamese concentration guidelines. In the downstream estuarine area, the intrusion of marine waters diluted water flowing from HCMC, leading water quality to return close to the state observed upstream from HCMC. In general, levels of nutrient and metal contaminations along the Saigon River during both seasons appear moderate regarding to Vietnamese and WHO guidelines although the urban area is highlighted as the major contributor for metal(oid) emissions. Finally, we showed that apart from wastewater and industrial discharges that affect the river quality, metal(oid) partitioning between solid and solution is controlled by the change in water geochemistry along the continuum during both seasons, such as DO (e.g., for As and Cr) and pH (e.g., for Pb) which drives their sorption/dissolution dynamics.

International audience; The use of antibiotics in both human and veterinary medicine has led to increased presence of these compounds and antibiotic resistance in the environment. In this study, the effect of low, environmentally relevant (mg L-1) concentrations of vancomycin (VA), flumequine (FLU), and sulfamethoxazole (SMX) on nitrate reduction rates was studied in river sediments. Nitrate reduction rates were determined by supplying intact sediments for several weeks with both nitrate and antibiotics (ng L-1, mu g L-1, and mg L-1 concentrations), including a non-amended control. Furthermore the concentrations of the three investigated antibiotics were measured in the initial (natural) sediments and the sediments supplied with the antibiotics. The antibiotic concentrations in the sediments decreased (on average 62% for FLU and 93% for SMX) during the experiments, indicating loss of antibiotics due to sorption or (bio) degradation. Nitrate reduction rates were not affected by environmental concentrations of VA, FLU and SMX. FLU and SMX only partially inhibited nitrate reduction rates at high, therapeutic concentrations by 41 and 39% respectively. The three tested antibiotics significantly enhanced the production of nitrite, an intermediate in dissimilatory nitrate reduction. Nitrite production increased 1.9 and 1.4 fold for environmental VA concentrations (107 and 187 mu g L-1 respectively), application of 58 mg L-1 SMX resulted in a 7.5 fold increase and augmented 16 and 8.5 fold in the presence of respectively 13 mu g L-1 and 52 mg L-1 FLU. Even though inhibition of nitrate reduction rates was observed at therapeutic antibiotic concentrations, nitrate reduction proceeded under all experimental conditions, indicating the presence of resistance toward these antibiotics among the nitrate reducing bacteria. The accumulation of nitrite suggests that the nitrite reduction step was more affected than the overall nitrate reduction process. (C) 2013 Elsevier Ltd. All rights reserved.

Occurrence and fate of 17 antibiotics were investigated in the aqueous phase of river water under different hydrological conditions at 5 sampling locations in the Seine River inner estuary. The target analytes belonged to 4 groups: quinolones, sulfonamides, nitro-imidazoles and diaminopyrimidines. This six-month survey (from January to June 2006) showed that different compounds were occurring at individual concentrations reaching 544 ng L− 1 (sulfamethoxazole). All 17 compounds were detected at least once in the survey. Sulfamethoxazole was detected in every sample, and showed the highest concentrations. Norfloxacin and flumequine were found to be the most ubiquitous quinolones, with detection frequencies of 33 and 75% respectively at the most contaminated site (Poses). Investigations concerning the origins of this contamination were made by means of a longitudinal profile along the Seine River between Paris and Poses. It showed large inputs of norfloxacin, ofloxacin, trimethoprim and sulfamethoxazole from wastewater treatment plants, with an increase in norfloxacin and sulfamethoxazole concentrations of 84% and 70% respectively, both reaching 155 ng L− 1 in the river, downstream from a wastewater outlet. The detected compounds showed different dissipation patterns and behaviours under different hydrological conditions. Higher inputs of norfloxacin were found in low flow conditions, which were rapidly attenuated along the stream. In contrast, sulfamethoxazole inputs were increasing in high flow conditions, and dissipation of this compound was found to be slow. Similar behaviour was observed for the synergist trimethoprim. Flumequine was also frequently detected and its input increased during flood events.