Paradise lost? Pesticide pollution in a European region with considerable amount of traditional agriculture

Pesticide contamination of agricultural streams has widely been analysed in regions of high intensity agriculture such as in Western Europe or North America. The situation of streams subject to low intensity agriculture relying on human and animal labour, as in parts of Romania, remains unknown. To close this gap, we determined concentrations of 244 pesticides and metabolites at 19 low-order streams, covering sites from low to high intensity agriculture in a region of Romania. Pesticides were sampled with two passive sampling methods (styrene-divinylbenzene (SDB) disks and polydimethylsiloxane (PDMS) sheets) during three rainfall events and at base flow. Using the toxic unit approach, we assessed the toxicity towards algae and invertebrates. Up to 50 pesticides were detected simultaneously, resulting in sum concentrations between 0.02 and 37 µg L^-1. Both, the sum concentration as well as the toxicities were in a similar range as in high intensity agricultural streams of Western Europe. Different proxies of agricultural intensity did not relate to in-stream pesticide toxicity, contradicting the assumption of previous studies. The toxicity towards invertebrates was positively related to large scale variables such as the catchment size and the agricultural land use in the upstream catchment and small scale variables including riparian plant height, whereas the toxicity to algae showed no relationship to any of the variables. Our results suggest that streams in low intensity agriculture, despite a minor reported use of agrochemicals, exhibit similar levels of pesticide pollution as in regions of high intensity agriculture.

Wide-scope target screening of >2000 emerging contaminants in wastewater samples with UPLC-Q-ToF-HRMS/MS and smart evaluation of its performance through the validation of 195 selected representative analytes

This study presents the development and validation of a comprehensive quantitative target methodology for the analysis of 2316 emerging pollutants in water based on Ultra-Performance Liquid Chromatography Quadrupole-Time-Of-Flight Mass Spectrometry (UPLC-Q-ToF-HRMS/MS). Target compounds include pesticides, pharmaceuticals, drugs of abuse, industrial chemicals, doping compounds, surfactants and transformation products, among others. The method was validated for 195 analytes, chosen to be representative of the chemical space of the target list, enabling the assessment of the performance of the method. The method involves a generic sample preparation based on mixed mode solid phase extraction, a UPLC-QTOF-MS/MS screening method using Data Independent Acquisition (DIA) mode, which provides MS and MS/MS spectra simultaneously and an elaborate strong post-acquisition evaluation of the data. The processing method was optimized to provide a successful identification rate >95 % and to minimize the number of false positive results (< 5 %). Decision limit (CCα) and detection capability (CCβ) were also introduced in the validation scheme to provide more realistic metrics on the performance of a HRMS-based wide-scope screening method. A new system of identification points (IPs) based on the one described in the Commission Decision 2002/657/EC was applied to communicate the confidence level in the identification of the analytes. This system considers retention time, mass accuracy, isotopic fit and fragmentation; taking full advantage of the capacities of the HRMS instruments. Finally, 398 contaminants were detected and quantified in real wastewater.

Comparison of different types of landfill leachate treatments by employment of nontarget screening to identify residual refractory organics and principal component analysis

Three different chemical oxidation processes were investigated in terms of their capability to degrade organic chemical components of real mature landfill-leachate in combination with biological treatment run in a Sequencing Batch Biofilter Granular Reactor (SBBGR). H₂O₂, H₂O₂ + UV and O₃ were integrated with SBBGR and respective effluents were analyzed and compared with the effluent obtained from biological SBBGR treatment alone. In agreement with their respective oxidative power, conventional bulk parameters (residual COD, TOC, N_tot, TSS) determined from the resulting effluents evidenced the following efficacy ranking for degradation: SBBGR/O₃ > SBBGR/UV + H₂O₂ > SBBGR/H₂O₂ > SBBGR. A more detailed characterization of the organic compounds was subsequently carried out for the four treated streams. For this, effluents were first subjected to a sample preparation step, allowing for a classification in terms of acidic, basic, strongly acidic and strongly basic compounds, and finally to analysis by liquid chromatography/high resolution mass spectrometry (LC/HR-MS). This classification, combined with further data post-processing (non-target screening, Venn Diagram, tri-dimensional plot and Principal Component Analysis), evidenced that the SBBGR/H₂O₂ process is comparable to the pure biological oxidation. In contrast, SBBGR/O₃ and SBBGR/UV + H₂O₂ not only resulted in a very different residual composition as compared to SBBGR and SBBGR/H₂O₂, but also differ significantly from each other. In fact, and despite of the SBBGR/O₃ being the most efficient process, this treatment remained chemically more similar to SBBGR/H₂O₂ than to SBBGR/UV + H₂O₂. This finding may be attributable to different mechanism of degradation involved with the use of UV radiation. Apart from these treatment differences, a series of recalcitrant compounds was determined in all of the four treatments and partly identified as hetero-poly-aromatic species (humic acids-like species).

Nontarget Screening with High Resolution Mass Spectrometry in the Environment: Ready to Go?

The vast, diverse universe of organic pollutants is a formidable challenge for environmental sciences, engineering, and regulation. Nontarget screening (NTS) based on high resolution mass spectrometry (HRMS) has enormous potential to help characterize this universe, but is it ready to go for real world applications? In this Feature article we argue that development of mass spectrometers with increasingly high resolution and novel couplings to both liquid and gas chromatography, combined with the integration of high performance computing, have significantly widened our analytical window and have enabled increasingly sophisticated data processing strategies, indicating a bright future for NTS. NTS has great potential for treatment assessment and pollutant prioritization within regulatory applications, as highlighted here by the case of real-time pollutant monitoring on the River Rhine. We discuss challenges for the future, including the transition from research toward solution-centered and robust, harmonized applications.

Pesticides drive risk of micropollutants in wastewater-impacted streams during low flow conditions

Micropollutants enter surface waters through various pathways, of which wastewater treatment plants (WWTPs) are a major source. The large diversity of micropollutants and their many modes of toxic action pose a challenge for assessing environmental risks. In this study, we investigated the potential impact of WWTPs on receiving ecosystems by describing concentration patterns of micropollutants, predicting acute risks for aquatic organisms and validating these results with macroinvertebrate biomonitoring data. Grab samples were taken upstream, downstream and at the effluent of 24 Swiss WWTPs during low flow conditions across independent catchments with different land uses. Using liquid chromatography high resolution tandem mass spectrometry, a comprehensive target screening of almost 400 organic substances, focusing mainly on pesticides and pharmaceuticals, was conducted at two time points, and complemented with the analysis of a priority mixture of 57 substances over eight time points. Acute toxic pressure was predicted using the risk assessment approach of the multi-substance potentially affected fraction, first applying concentration addition for substances with the same toxic mode of action and subsequently response addition for the calculation of the risk of the total mixture. This toxic pressure was compared to macroinvertebrate sensitivity to pesticides (SPEAR index) upstream and downstream of the WWTPs. The concentrations were, as expected, especially for pharmaceuticals and other household chemicals higher downstream than upstream, with the detection frequency of plant protection products upstream correlating with the fraction of arable land in the catchments. While the concentration sums downstream were clearly dominated by pharmaceuticals or other household chemicals, the acute toxic pressure was mainly driven by pesticides, often caused by the episodic occurrence of these compounds even during low flow conditions. In general, five single substances explained much of the total risk, with diclofenac, diazinon and clothianidin as the main drivers. Despite the low predicted acute risk of 0%-2.1% for affected species, a significant positive correlation with macroinvertebrate sensitivity to pesticides was observed. However, more effect data for pharmaceuticals and a better quantification of episodic pesticide pollution events are needed for a more comprehensive risk assessment.

Rapid Screening for Exposure to "Non-Target" Pharmaceuticals from Wastewater Effluents by Combining HRMS-Based Suspect Screening and Exposure Modeling

Active pharmaceutical ingredients (APIs) have raised considerable concern over the past decade due to their widespread detection in water resources and their potential to affect ecosystem health. This triggered many attempts to prioritize the large number of known APIs to target monitoring efforts and testing of fate and effects. However, so far, a comprehensive approach to screen for their presence in surface waters has been missing. Here, we explore a combination of an automated suspect screening approach based on liquid chromatography coupled to high-resolution mass spectrometry and a model-based prioritization using consumption data, readily predictable fate properties and a generic mass balance model for activated sludge treatment to comprehensively detect APIs with relevant exposure in wastewater treatment plant effluents. The procedure afforded the detection of 27 APIs that had not been covered in our previous target method, which included 119 parent APIs. The newly detected APIs included seven compounds with a high potential for bioaccumulation and persistence, and also three compounds that were suspected to stem from point sources rather than from consumption as medicines. Analytical suspect screening proved to be more selective than model-based prioritization, making it the method of choice for focusing analytical method development or fate and effect testing on those APIs most relevant to the aquatic environment. However, we found that state-of-the-practice exposure modeling used to predict potential high-exposure substances can be a useful complement to point toward oversights and known or suspected detection gaps in the analytical method, most of which were related to insufficient ionization.

Quantitative target and systematic non-target analysis of polar organic micro-pollutants along the river Rhine using high-resolution mass-spectrometry--Identification of unknown sources and compounds

In this study, the contamination by polar organic pollutants was investigated along the Rhine River, an important source of drinking water for 22 million people in central Europe. Following the flow of the river, a traveling water mass was sampled using weekly flow-proportional composite samples at ten different downstream sites, including main tributaries. Using a broad analytical method based on solid phase extraction and high-resolution mass spectrometry, the water was analyzed for more than 300 target substances. While the water in Lake Constance contained only 83 substances in often low concentrations, the number of detects found in the water phase increased to 143 substances and a weekly load of more than 7 tons at the last sampling site, the Dutch-German border. Mostly present were chemicals originating from wastewater treatment plants, especially the artificial sweetener Acesulfam and two pharmaceuticals, Metformin and Gabapentin, which dominate the weekly load up to 58%. Although the sample campaign was performed in a dry period in early spring, a large variety of pesticides and biocides were detected. Several industrial point sources were identified along the waterway's 900 km journey, resulting in high concentrations in the tributaries and loads of up to 160 kg. Additionally, an unbiased non-target analysis was performed following two different strategies for the prioritization of hundreds of potentially relevant unknown masses. While for the first prioritization strategy, only chlorinated compounds were extracted from the mass spectrometer datasets, the second prioritization strategy was performed using a systematic reduction approach between the different sampling sites. Among others, two substances that never had been detected before in this river, namely, the muscle relaxant Tizanidine and the solvent 1,3-Dimethyl-2-imidazolidinone (DMI), were identified and confirmed, and their loads were roughly estimated along the river.

Strategies to characterize polar organic contamination in wastewater: exploring the capability of high resolution mass spectrometry

Wastewater effluents contain a multitude of organic contaminants and transformation products, which cannot be captured by target analysis alone. High accuracy, high resolution mass spectrometric data were explored with novel untargeted data processing approaches (enviMass, nontarget, and RMassBank) to complement an extensive target analysis in initial "all in one" measurements. On average 1.2% of the detected peaks from 10 Swiss wastewater treatment plant samples were assigned to target compounds, with 376 reference standards available. Corrosion inhibitors, artificial sweeteners, and pharmaceuticals exhibited the highest concentrations. After blank and noise subtraction, 70% of the peaks remained and were grouped into components; 20% of these components had adduct and/or isotope information available. An intensity-based prioritization revealed that only 4 targets were among the top 30 most intense peaks (negative mode), while 15 of these peaks contained sulfur. Of the 26 nontarget peaks, 7 were tentatively identified via suspect screening for sulfur-containing surfactants and one peak was identified and confirmed as 1,3-benzothiazole-2-sulfonate, an oxidation product of a vulcanization accelerator. High accuracy, high resolution data combined with tailor-made nontarget processing methods (all available online) provided vital information for the identification of a wider range of heteroatom-containing compounds in the environment.

Automatic recalibration and processing of tandem mass spectra using formula annotation

High accuracy, high resolution tandem mass spectrometry (MS/MS) is becoming more common in analytical applications, yet databases of these spectra remain limited. Databases require good quality spectra with sufficient compound information, but processing, calibration, noise reduction and retrieval of compound information are time-consuming tasks that prevent many contributions. We present a comprehensive workflow for the automatic processing of MS/MS using formula annotation for recalibration and cleanup to generate high quality spectra of standard compounds for upload to MassBank (www.massbank.jp). Compound information is retrieved via Internet services. Reference standards of 70 pesticides were measured at various collision energies on an LTQ-Orbitrap XL to develop and evaluate the workflow. A total of 944 resulting spectra are now available on MassBank. Evidence of nitrogen adduct formation during MS/MS fragmentation processes was found, highlighting the benefits high accuracy MS/MS offers for spectral interpretation. A database of recalibrated, cleaned-up spectra resulted in the most correct spectra ranked in first place, regardless of whether the search spectra were recalibrated or not, whereas the average rank of the correct molecular formula was improved from 2.55 (uncalibrated) to 1.53 when using recalibrated MS/MS data. The workflow is available as an R package RMassBank capable of generating MassBank records from raw MS and MS/MS data and can be adjusted to process data acquired with different settings and instruments. This workflow is a vital step towards addressing the need for more high quality, high accuracy MS/MS spectra in spectral databases and provides important information for spectral interpretation.

Multiresidue analysis of 88 polar organic micropollutants in ground, surface and wastewater using online mixed-bed multilayer solid-phase extraction coupled to high performance liquid chromatography-tandem mass spectrometry

An automated multiresidue method consisting of an online solid-phase extraction step coupled to a high performance liquid chromatography-tandem mass spectrometer (online-SPE-HPLC-MS/MS method) was developed for the determination of 88 polar organic micropollutants with a broad range of physicochemical properties (logD(OW) (pH 7): -4.2 to 4.2). Based on theoretical considerations, a single mixed-bed multilayer cartridge containing four different extraction materials was composed for the automated enrichment of water samples. This allowed the simultaneous analysis of pesticides, biocides, pharmaceuticals, corrosion inhibitors, many of their transformation products, and the artificial sweetener sucralose in three matrices groundwater, surface water, and wastewater. Limits of quantification (LOQs) were in the environmentally relevant concentration range of 0.1-87 ng/L for groundwater and surface water, and 1.5-206 ng/L for wastewater. The majority of the compounds could be quantified below 10 ng/L in groundwater (82%) and surface water (80%) and below 100 ng/L in wastewater (80%). Relative recoveries were largely between 80 and 120%. Intraday and inter-day precision, expressed as relative standard deviation, were generally better than 10% and 20%, respectively. 50 isotope labeled internal standards were used for quantification and accordingly, relative recoveries as well as intraday and inter-day precision were better for compounds with corresponding internal standard. The applicability of this method was shown during a sampling campaign at a riverbank filtration site for drinking water production with travel times of up to 5 days. 36 substances of all compound classes investigated could be found in concentrations between 0.1 and 600 ng/L. The results revealed the persistence of carbamazepine and sucralose in the groundwater aquifer as well as degradation of the metamizole metabolite 4-acetamidoantipyrine.

Transformation of beta-lactam antibacterial agents during aqueous ozonation: reaction pathways and quantitative bioassay of biologically-active oxidation products

Reactions of ozone (O3) with the beta-lactam antibiotics penicillin G (PG) and cephalexin (CP) have previously been found to yield products retaining antibacterial activities. These products are unequivocally identified here as the stereoisomeric (R)-sulfoxides of each parent molecule and characterized by a combination of chemical analysis and an antibacterial activity assay. PG-(R)-sulfoxide, which is approximately 15% as potent as PG itself, is formed in approximately 55% yield, whereas CP-(R)-sulfoxide, which is 83% as active as CP, is formed with a maximum 34% yield. PG-(R)-sulfoxide is recalcitrant toward further oxidation by O3, but readily transformed by hydroxyl radical (HO*) (kHO*,app"=7.4x10(9) M(-1) s(-1), pH 7), resulting in quantitative elimination of its antibacterial activity. In contrast, CP-(R)-sulfoxide is degraded by both O3 and HO* (kO3,app"=2.6x10(4) M(-1) s(-1) and kHO*,app"= 7.6x10(9) M(-1) s(-1), pH 7), leading to quantitative elimination of its antibacterial activity. During ozonation of a secondary municipal wastewater effluent sample (pH 8.1, CDOC=4.0 mg/L, [alkalinity]=3.6 mM as HCO3-) spiked with [PG]0=1 microM, PG-(R)-sulfoxide yields did not exceed 0.15 microM for O3 doses up to 100 microM (4.8 mg/L), but reached 0.47 microM with 10-mM t-BuOH added as a HO* scavenger. In contrast, CP-(R)-sulfoxide yields did not exceed 0.1 microM for the same wastewater spiked with [CP]0=1 microM in either the presence or absence of t-BuOH, indicating that CP-(R)-sulfoxide transformation is governed primarily by direct reaction with O3. These findings suggest that, for a given degree of parent compound transformation, PG-(R)-sulfoxide yields would likely be greatest during ozonation of wastewaters characterized by low O3 demands and high HO* scavenging rates, whereas CP-(R)-sulfoxide yields would be less matrix-dependent. In general, complete deactivation of penicillins during wastewater treatment will likely require higher O3 exposures than necessary for deactivation of cephalosporins.

Identification of transformation products of organic contaminants in natural waters by computer-aided prediction and high-resolution mass spectrometry

Transformation products (TPs) of organic contaminants in aquatic environments are still rarely considered in water quality and chemical risk assessment, although they have been found in concentrations that are of concern. Since many different TPs can potentially be formed in the environment and analytical standards are typically lacking for these compounds, knowledge on the prevalence of TPs in aquatic environments is fragmentary. In this study, an efficient procedure was therefore developed to comprehensively screen for large numbers of potential TPs in environmental samples. It is based on a target list of plausible TPs that has been assembled using the University of Minnesota Pathway Prediction System (UM-PPS) for the computer-aided prediction of products of microbial metabolism and an extensive search for TPs reported in the scientific literature. The analytical procedure for screening of the compounds on the target list has been developed to allow for the detection of a broad range of compounds in complex environmental samples in the absence of commercially available reference standards. It includes solid phase extraction with broad enrichment efficiency, followed by liquid chromatography and tandem mass spectrometry with high mass resolution and accuracy. The identification of target TPs consisted of extracting the exact mass from the chromatogram, selecting peaks of sufficient intensity, checking the plausibility of the retention time, and interpreting mass spectra. The procedure was used to screen for TPs of 52 pesticides, biocides, and pharmaceuticals in seven representative surface water samples from different regions in Switzerland. Altogether, 19 TPs were identified, including both some well-known and commonly detected TPs, and some rarely reported ones (e.g., biotransformation products of the pharmaceuticals venlafaxine and verapamil, or of the pesticide azoxystrobin). Overall, the rather low number of TPs detected suggests that TPs may not pose a problem of unexpected magnitude for aquatic resources.

Dissipation and transport of veterinary sulfonamide antibiotics after manure application to grassland in a small catchment

The heavy use of veterinary antibiotics in modern animal production causes concern about risks of spreading antibiotic resistance after manure applications to agricultural fields. We report on a field study aiming at elucidating the fate of sulfonamide (SA) antibiotics in grassland soils and their transport to surface water. Two controlled manure applications were carried out under different weather conditions. After both applications, the SA concentrations in pore water and the total soil content declined rapidly. This stage of fast decline was followed by a second one during which the SA were rather persistent. More than 15% of the SAs applied were still present in the soil 3 months after application, always exceeding 100 microg/kg topsoil. The apparent SA sorption increased strongly with time. Accordingly, the risk for SA losses to water bodies decreased within 2 weeks to very low values. In contrast to SA concentrations in the soil, losses to the brook were strongly influenced by the weather conditions after the two manure applications. The overall losses were 15 times larger (about 0.5% of applied SA) during the wet conditions of May 2003 compared to the dry conditions following the first application (March 2003).

Exhaustive extraction of sulfonamide antibiotics from aged agricultural soils using pressurized liquid extraction

A pressurized liquid extraction (PLE) method was developed for the quantification of five sulfonamide antibiotics (sulfadiazine, sulfadimethoxine, sulfamethazine, sulfamethoxazole, and sulfathiazole) in aged soil samples. To account for sequestration effects the extraction was optimized using a composite grassland soil sample collected 11 days after the application of manure containing these substances. The optimized method uses a mixture of buffered water (pH 8.8) and acetonitrile (85:15) as solvent for the extraction at 200 degrees C and 100 bar during five min. The most important parameter for the extraction efficiency was temperature whereas the pH of the extraction solvent did hardly influence extraction efficiency between pH 4.1 and 8.8. A temperature increase from 100 to 200 degrees C improved the extraction efficiency up to a factor of six for aged residues in soils. In contrast, no temperature dependence was observed during short-term spike experiment. After 90 min exposure in these spike experiments we recovered 62-93% of the sulfonamides, except for sulfamethoxazole with only 41%. These percentages decreased substantially after a contact time of 6 and 17 days. The reasons for this decline remained unknown. Inter-day precision of the method was very satisfactory: relative standard deviations from the average were below 10%. Limits of detection for the extraction procedure were lower than 15 microg/kg. The performance of the developed extraction method was demonstrated by measuring the decrease of sulfonamide concentration in a top soil after manure application. Within 3 months the concentration of sulfadiazine dropped from 450 to 150 microg/kg.

Fully automated online solid phase extraction coupled directly to liquid chromatography-tandem mass spectrometry. Quantification of sulfonamide antibiotics, neutral and acidic pesticides at low concentrations in surface waters

A fully automated online solid phase extraction-liquid chromatography-tandem mass spectrometry (SPE-LC-MS/MS) instrumental setup has been developed for the quantification of sulfonamide antibiotics and pesticides in natural water. The direct coupling of an online solid phase extraction cartridge (Oasis HLB) to LC-MS/MS was accomplished using column switching techniques. High sensitivity in the low ng/L range was achieved by large volume injections of 18 mL with a combination of a tri-directional auto-sampler and a dispenser system. This setup allowed high sample throughput with a minimum of investment costs. Special emphasis was placed on low cross contamination. The chosen approach is suitable for research as well as for monitoring applications. The flexible instrumental setup was successfully optimised for different important groups of bioactive chemicals resulting in three trace analytical methods for quantification of (i) sulfonamide antibiotics and their acetyl metabolites; (ii) neutral pesticides (triazines, phenylureas, amides, chloracetanilides) and (iii) acidic pesticides (phenoxyacetic acids and triketones). Absolute extraction recoveries from 85 to 112% were obtained for the different analytes. More than 500 samples could be analyzed with one extraction cartridge. The inter-day precision of the method was excellent indicated by relative standard deviations between 1 and 6%. High accuracy was achieved by the developed methods resulting in maximum deviation relative to the spiked amount of 8-15% for the different analytes. Detection limits for various environmental samples were between 0.5 and 5 ng/L. Matrix induced ion suppression was in general smaller than 25%. The performance of the online methods was demonstrated with measurements of concentration dynamics of sulfonamide antibiotics and pesticides concentrations in a little creek during rain fall events.

Quantification of the new triketone herbicides, sulcotrione and mesotrione, and other important herbicides and metabolites, at the ng/l level in surface waters using liquid chromatography-tandem mass spectrometry

The LC/ESI/MSMS method allows the trace quantification (ng/l) of the new triketone herbicides, i.e. sulcotrione and mesotrione, and important herbicides and metabolites, in natural waters. Solid phase extraction (SPE) for sample enrichment is performed with OASIS (recoveries 94-112% for parent herbicides). Neutral and acidic compounds were analyzed separately with ESI in positive and negative mode, respectively. Quantification limits varied between 0.5 and 10 ng/l. The acidic herbicides detection was improved by a neutralizing post-column addition solution. The influence of ion suppression on quantification is discussed in detail. It is shown that we could overcome this problem and achieve reliable quantification using isotope labeled internal standards (ILIS) for every single analyte. The methods performance is illustrated with samples from a lake depth profile.

Occurrence and fate of carbamazepine, clofibric acid, diclofenac, ibuprofen, ketoprofen, and naproxen in surface waters

Although various single-concentration measurements of pharmaceuticals are available in the literature, detailed information on the variation over time of the concentration and the load in wastewater effluents and rivers and on the fate of these compounds in the aquatic environment are lacking. We measured the concentrations of six pharmaceuticals, carbamazepine, clofibric acid, diclofenac, ibuprofen, ketoprofen, and naproxen, in the effluents of three wastewater treatment plants (WWTPs), in two rivers and in the water column of Lake Greifensee (Switzerland) over a time period of three months. In WWTP effluents, the concentrations reached 0.95 microg/L for carbamazepine, 0.06 microg/L for clofibric acid, 0.99 microg/L for diclofenac, 1.3 microg/L for ibuprofen, 0.18 microg/L for ketoprofen, and 2.6 microg/L for naproxen. The relative importance in terms of loads was carbamazepine, followed by diclofenac, naproxen, ibuprofen, clofibric acid, and ketoprofen. An overall removal rate of all these pharmaceuticals was estimated in surface waters, under real-world conditions (in a lake), using field measurements and modeling. Carbamazepine and clofibric acid were fairly persistent. Phototransformation was identified as the main elimination process of diclofenac in the lake water during the study period. With a relatively high sorption coefficient to particles, ibuprofen might be eliminated by sedimentation. For ketoprofen and naproxen, biodegradation and phototransformation might be elimination processes. For the first time, quantitative data regarding removal rates were determined in surface waters under real-world conditions. All these findings are important data for a risk assessment of these compounds in surface waters.

Phototransfomation of ticlosan in surface waters: a relevant elimination process for this widely used biocide--laboratory studies, field measurements, and modeling

The phototransformation of the widely used biocide triclosan (5-chloro-2-(2,4-dichlorophenoxy)phenol) was quantified for surface waters using artificial UV light and sunlight irradiation. The pH of surface waters, commonly ranging from 7 to 9, determines the speciation of triclosan (pKa = 8.1) and therefore its absorption of sunlight. Direct phototransformation of the anionic form with a quantum yield of 0.31 (laboratory conditions at 313 nm) was identified as the dominant photochemical degradation pathway of triclosan. Combining the photochemical parameters with actual meteorological data and field measurements allowed us to validate a model describing the behavior of triclosan in the water column of a Swiss lake (Lake Greifensee). From August to October 1999, direct phototransformation accounted for 80% of the observed total elimination of triclosan from the lake. The remaining major sink for triclosan was the loss in the outflow. Thus, during the summer season, direct phototransformation appears to be a major elimination pathway of triclosan in this lake. Based on absorption spectra and quantum yield data, the phototransformation half-lives of triclosan were calculated under various environmental conditions typical for surface waters. Daily averaged half-lives were found to vary from about 2 to 2000 days, depending on latitude and time of year.

Sources of pesticides in surface waters in Switzerland: pesticide load through waste water treatment plants--current situation and reduction potential

Concentrations of pesticides in Swiss rivers and lakes frequently exceed the Swiss quality goal of 0.1 microg/l for surface waters. In this study, concentrations of various pesticides (e.g., atrazine, diuron, mecoprop) were continuously measured in the effluents of waste water treatment plants and in two rivers during a period of four months. These measurements revealed that in the catchment of Lake Greifensee, farmers who did not perfectly comply with 'good agricultural practice' caused at least 14% of the measured agricultural herbicide load into surface waters. Pesticides, used for additional purposes in urban areas (i.e. protection of materials, conservation, etc.), entered surface waters up to 75% through waste water treatment plants.

Simultaneous quantification of neutral and acidic pharmaceuticals and pesticides at the low-ng/l level in surface and waste water

A new analytical method is presented that allows simultaneous determination of neutral and acidic pharmaceuticals and pesticides in natural waters. The compounds investigated include frequently used pharmaceuticals, i.e., the anti-epileptic carbamazepine, four analgesic/anti-flammatory drugs (ibuprofen, diclofenac, ketoprofen and naproxen) and the lipid regulator clofibric acid and important pesticides including triazines, acetamides and phenoxy acids. Sample enrichment was achieved in one step with a newly developed solid-phase extraction procedure using the Waters Oasis HLB sorbent. The neutral compounds were analyzed by GC-MS in a first step, and then the acidic compounds after derivatization with diazomethane. Relative recoveries using isotope labeled internal standards were between 71 and 118% and the detection limits were in the range of 1 to 10 ng/l in drinking water, surface water and waste water treatment plant effluents (precision: 1-15%). The developed analytical method proved to be very durable during a 3-month field study and the target analytes were detected in concentrations of 5-3,500 ng/l in waste water treatment plant effluents, river water and lake water.