Investigative monitoring of pesticide and nitrogen pollution sources in a complex multi-stressed catchment: The lower Llobregat River basin case study (Barcelona, Spain).

The management of the anthropogenic water cycle must ensure the preservation of the quality and quantity of water resources and their careful allocation to the different uses. Protection of water resources requires the control of pollution sources that may deteriorate them. This is a challenging task in multi-stressed catchments. This work presents an approach that combines pesticide occurrence patterns and stable isotope analyses of nitrogen (δ15N-NO3-, δ15N-NH4+), oxygen (δ18O-NO3-), and boron (δ11B) to discriminate the origin of pesticides and nitrogen-pollution to tackle this challenge. The approach has been applied to a Mediterranean sub-catchment subject to a variety of natural and anthropogenic pressures. Combining the results from both analytical approaches in selected locations of the basin, the urban/industrial activity was identified as the main pressure on the quality of the surface water resources, and to a large extent also on the groundwater resources, although agriculture may play also an important role, mainly in terms of nitrate and ammonium pollution. Total pesticide concentrations in surface waters were one order of magnitude higher than in groundwaters and believed to originate mainly from soil and/or sediments desorption processes and urban and industrial use, as they were mainly associated with treated wastewaters. These findings were supported by the stable isotope results that pointed to an organic origin of nitrate in surface waters and most groundwater samples. Ammonium pollution observed in some aquifer locations is probably generated by nitrate reduction. Overall, no significant attenuation processes could be inferred for nitrate pollution. The approach presented here exemplifies the investigative monitoring envisioned in the Water Framework Directive.

Monitoring the complex occurrence of pesticides in the Llobregat basin, natural and drinking waters in Barcelona metropolitan area (Catalonia, NE Spain) by a validated multi-residue online analytical method.

The European Directive 98/83/CE legislates the presence of pesticides in drinking water, but apart from a few compounds, nothing is said about which pesticides should be monitored. Nevertheless, water companies need to go beyond the accomplishment of the legislation and find out pesticide contamination in all sources of water in order to manage the hazard assessment, and to guarantee safe drinking water to all the population. The aim of this work was to develop an analytical multi-residue method for circa 100 compounds. The method analyses previously monitored compounds in Barcelona city and its metropolitan area, as well as many emerging pesticides and some transformation products. An on-line sample extraction (0.75 mL) coupled to fast UHPLC-MS/MS method was developed. Good linearity (r2 > 0.995, with less residuals than 15%), accuracies and precisions under 25%, and acceptable expanded uncertainties were obtained for most of the monitored compounds, according to ISO/IEC 17025, obtaining limits of quantification between 5 and 25 ng/L for all compounds. A monitoring campaign on natural and treated waters in the Barcelona metropolitan area was carried out during 2016-2017. Results showed that pesticide contamination at the low stretch of Llobregat River and in its aquifer is severe. The maximum concentrations were in the range of few µg/L for carbendazim, DEET, diuron and propiconazole, and in the range 0.1-0.5 µg/L for bentazone, imidacloprid, isoproturon, simazine, metazachlor, methomyl, terbutryn and tebuconazole. However, the efficiency of advanced treatments in the DWTPs involved in drinking water production in the Barcelona metropolitan area allows the complete removal of pesticides and a safe water production for consumers. The method shows a good analytical performance for most compounds with a fast sample preparation and analysis. In addition, it has updated the knowledge about the occurrence of pesticides in the Barcelona city area.

Bioavailability and biodegradation of nonylphenol in sediment determined with chemical and bioanalysis.

The surfactant nonylphenol (NP) is an endocrine-disrupting compound that is widely spread throughout the environment. Although environmental risk assessments are based on total NP concentrations, only the bioavailable fraction possess an environmental risk. The present study describes the bioavailability and biodegradability of NP over time in contaminated river sediment of a tributary of the Ebro River in Spain. The bioavailable fraction was collected with Tenax TA(R) beads, and biodegradation was determined in aerobic batch experiments. The presence of NP was analyzed chemically using gas chromatography-mass spectrometry and indirectly as estrogenic potency using an in vitro reporter gene assay (ER(alpha)-luc assay). Of the total extractable NP in the sediment, 95%+/-1.5% (mean +/- standard error) desorbed quickly into the water phase. By aerobic biodegradation, the total extractable NP concentration and the estrogenic activity were reduced by 97%+/-0.5% and 94%+/-2%, respectively. The easily biodegradable fraction equals the potential bioavailable fraction. Only 43 to 86% of the estrogenic activity in the total extractable fraction, as detected in the ER(alpha)-luc assay, could be explained by the present NP concentration. This indicates that other estrogenic compounds were present and that their bioavailability and aerobic degradation were similar to that of NP. Therefore, we propose to use NP as an indicator compound to monitor estrogenicity of this Ebro River sediment. To what extent this conclusion holds for other river sediments depends on the composition of the contaminants and/or the nature of these sediments and requires further testing.

Tenax extraction as a tool to evaluate the availability of polybrominated diphenyl ethers, DTT, and DTT metabolites in sediments.

Solid-phase extraction with Tenax is one of the most used methods for determining the fraction of a pollutant that desorbs rapidly from sediment and thus is available for living beings. In the present study, this technique has been applied to sediment contaminated in the laboratory with polybrominated diphenyl ethers (PBDEs) and dichlorodiphenyltrichloroethane, dichlorodifenyldichloroethylene, and dichlorodifenyldichloroethane (generically, DDXs). The amount of chemical retained in sediment during the time of the experiment fit well with a three-phase exponential desorption model. The ratios between the rapidly desorbing fraction and the fraction desorbed during a fixed time (6 or 24 h) were calculated. The fraction desorbed in 6 h was lower than the rapidly desorbing fraction for most of PBDEs, whereas the fraction desorbed in 24 h exceeded the rapidly desorbing fraction for both groups of compounds. However, variability of these data suggests, when possible, a long time measure of desorption in order to achieve a more accurate estimation. Both the extent and the velocity of desorption were inversely related with the bromination degree and, consistently, with hydrophobicity and molecular size. In this way, low brominated PBDEs and DDXs showed a high availability relative to high brominated PBDEs.

Spatial variation of DDT and its metabolites in fish and sediment from Cinca River, a tributary of Ebro River (Spain).

The Cinca River is a tributary of Ebro River in the NE of Spain which receives input from different activities. One of the most important is related to an industry where DDT is used as an intermediate in the production of dicofol. This study evaluated the DDT contamination along the Cinca River. Sampling sites were selected up- and downstream from this industry. Sediments and fishes (59 bleaks (Alburnus alburnus) and 23 barbels (Barbus graellsi)) were collected in 2002 and analyzed using a new and rapid selective pressurized liquid extraction (SPLE) method. DDT and its metabolites were found in sediments and fishes at levels ranging from 9 to 94microg kg(-1) dry weight (d.w.) and from not detected to 2098microg kg(-1) wet weight (w.w.), respectively. The highest values corresponded to samples collected just downstream the industry. Thirty kilometers downstream from the factory, levels were clearly lower, showing a weakening of the impact. p,p'-DDE isomer comprised up to 50% and 70% of total DDT measured in sediment and fish, respectively. When compared with values obtained in a previous study in 1999, a generalized drop of the levels in all matrixes (77-97%), was observed. No meaningful differences were found between the two fish species studied neither between the two tissues (muscle and liver) analyzed.

Occurrence of polybrominated diphenylethers, polychlorinated dibenzo-p-dioxins, dibenzofurans and biphenyls in coastal sediments from Spain.

Fifteen sediment samples were analysed in order to determine their content of polybrominated diphenylethers (PBDEs), polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and biphenyls (PCBs). Samples were collected from several hot spots on the Spanish coast, such as the harbours of Almeria and Tarragona, and the mouths of the Besos and Llobregat rivers in Barcelona. A generic analytical procedure based on Soxhlet extraction followed by an automated cleanup system and gas chromatography-ion trap-mass spectrometry was employed for determining the toxic congeners of PCDDs and PCDFs, as well as dioxin-like PCBs. As regards PBDE determinations, a rapid method based on the use of selective pressurized liquid extraction followed by gas chromatography-negative ion chemical ionization-mass spectrometry was applied. Total toxicity equivalent (WHO-TEQ) values were calculated using the toxicity equivalent factors proposed by WHO for dioxin-like PCBs, PCDDs and PCDFs. WHO-TEQ values ranged from 0.3 to 75 pg/g dry weight (dw), with PCB contribution on the toxicity of the samples between 1 and 84%. Total PBDE levels ranged from 2.7 to 134 ng/g dw, with BDE-209 contribution on the total PBDE contamination between 50 and 99%.

Brominated flame retardants in Alburnus alburnus from Cinca River Basin (Spain).

Thirty-two bleak fish (Alburnus alburnus) from three places along the Spanish River Cinca, a tributary of Ebro River, were collected for polybrominated diphenyl ether (PBDE) and hexabromocyclododecane (HBCD) determinations. Sampling sites corresponded to up- and downstream from Monzon, a heavily industrialized town draining to the river. Four different PBDE congeners (BDE-47, -153, -154 and -183) and HBCD were found at levels ranging from not detected (nd) to 573 ng/g wet weight for total PBDEs and from nd to 1643 ng/g wet weight for HBCD. The lowest values were found upstream of the industrialized area. Concentrations in fish were compared with previous data in sediment samples collected at the same sampling sites, and large fish to sediment ratios for these brominated compounds indicate that they are highly bioavailable. Moreover, PBDE and HBCD concentrations are correlated with fish length and weight indicating the bioaccumulation of these contaminants.

Occurrence and bioavailability of polybrominated diphenyl ethers and hexabromocyclododecane in sediment and fish from the Cinca River, a tributary of the Ebro River (Spain).

Fish and sediments from four places along the Spanish River Cinca were analyzed for polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD). The samples were collected up- and downstream from Monzón, a heavily industrialized town draining to the river. PBDEs and HBCD were found in sediments at levels ranging from 2 to 42 ng/g dry weight and from not detected (nd) to 514 ng/g dry weight, respectively. Twenty-three fish samples (Barbus graellsi) collected at the same places were also analyzed, showing levels from nd to 446 ng/g wet weight for PBDEs and from nd to 1172 ng/g wet weight for HBCD. The lowest values for both sediment and fish samples were found upstream of the industry. Of 40 congeners (from mono- to deca-BDEs) included in the analytical work, 8 PBDE congeners were detected in river sediments, whereas 17 different PBDEs were found in fish samples. Large fish-to-sediment ratios for these brominated compounds indicate that they are highly bioavailable, with the exception of deca-BDE which was only detected in sediment samples. Concentrations of PBDEs and HBCD were slightly higher in muscle tissues than in liver samples obtained from the same specimen of fish. Moreover, PBDE and HBCD concentrations are correlated with fish length indicating the bioaccumulation of these contaminants.

Determination of decabromodiphenyl ether in sediments using selective pressurized liquid extraction followed by GC-NCI-MS.

A method based on selective pressurized liquid extraction (SPLE) followed by gas chromatography-negative ion chemical ionization-mass spectrometry (GC-NCI-MS) has been evaluated for analysis of decabromodiphenyl ether (PBDE-209) in sediment samples. Instrumental operating conditions such as source temperature and system pressure were optimized in the NCI-MS system, giving an instrumental detection limit of 2 pg. The limit of determination of the entire SPLE-GC-NCI-MS procedure was around 50 pg g(-1) dry weight (dw), with repeatability of replicates between 4 and 21% relative standard deviation. Application of the method to 13 different river and marine sediment samples collected in Spain revealed that levels of decabromodiphenyl ether ranged between 2 and 132 ng g(-1) dry weight.

Potential chlorinated and brominated interferences on the polybrominated diphenyl ether determinations by gas chromatography-mass spectrometry.

The analysis of polybrominated diphenyl ether (PBDE) congeners by GC-MS was studied in terms of potential interferences. Different MS approaches were normally used for the PBDE analyses: negative ion chemical ionization (NICI-MS) and electron ionization (EI-MS). This paper studied the presence of potential interferences in each instrumental technique approach, principally those corresponding to different chlorinated compounds (PCBs, PCNs, etc.) as well as brominated compounds (PBBs, MeO-PBDEs, TBBPA, etc.). The two ionization modes are subjected to different types of interferences. In general, EI-MS is affected by chlorinated interferences, especially PCBs. NICI-MS eliminated chlorinated interferences but presented different brominated interferences, well resolved with the EI-MS approach.

Determination of 39 polybrominated diphenyl ether congeners in sediment samples using fast selective pressurized liquid extraction and purification.

In order to reduce time of analysis, a new pressurized liquid extraction (PLE) method that automatically and rapidly achieves quantitative and selective extraction of 39 polybrominated diphenyl ether (PBDE) congeners in sediment samples was optimized. It consists of on-line cleanup by inclusion of sorbents in the extraction cell. The new method was compared with a conventional method based on the use of Soxhlet extraction followed by solid-phase extraction (SPE) with cartridges. The instrumental determination was performed by GC-MS, using negative chemical ionization in the selected-ion monitoring mode. Recoveries from 47 to 82% were obtained for spiked tri- to hepta-PBDE congeners in sediment sample. The repeatability of replicate extractions was better than 15% relative standard deviation. The detection limits obtained with the new developed method were between 1 and 46 pg/g dry weight. The reduction in the sample preparation (extraction + cleanup) time (from days to 30 min) with a similar efficiency than that afforded by the conventional Soxhlet extraction-SPE cleanup technique indicates the suitability of this method. The method was applied to sediment samples where the analytes were detected in the range of 0.86-2.49 ng/g dry mass.