Plastics including microplastic (MP) particles are widely distributed in the environment today. Microcontaminants - especially very persistent organic compounds and trace metals - are also detected to a large extent in the (aquatic) environment, which has led to a growing number of recent studies addressing interactions between organic contaminants and (micro)plastics in the environment. The background of these studies is the presumed function of plastic particles as vectors for biomagnification, leading to negative effects on the ecosystem. In the present work, interactions between two common plastic polymers, low-density polyethylene (LD-PE) and rigid polyvinyl chloride (H-PVC), and three organic persistent compounds, dichlorodiphenyltrichloroethane (DDT), methoxychlor (DMDT), and dicofol with different log Kow-values, were investigated using a sorption assay and desorption experiments. A new and innovative experimental approach based on a static system resembling burial in deeper sediment layers was investigated. The experimental setup used additive-free plastic containers, resulting in an easy-to-use experiment instead of MP sorption. It is assumed that the basic mechanisms of interaction are evaluated and are material specific. The present sorption experiment demonstrated adsorption/incorporation of contaminants into the two polymers. Differences between the two polymers are addressed. In the sorption experiments, all target substances were detected in agreement with their hydrophobicity. In the desorption experiments, diffusion of contaminants from a contaminated sediment to the polymers was detected. As expected, sorption by PE was significantly higher. The differences between the two polymers are based on the different glass transition temperatures (Tg) and polymer structure. A comparison with published data from the Pellet Watch project shows a sorption capacity in the same concentration range. The simple approach is easy to use and illustrates the limited sorption capacity of the two polymers studied. It eliminates possible sorption effects on glass walls and simulates the ecosystem situation of a multiple aged contaminant mixture, which is usually not represented in laboratory experiments. The same approach is applicable to polystyrene, polypropylene and polyethylene terephthalate beside other polymer containers.

Currently, there are still no harmonized and thus reproducible methods for microplastics (MP) sampling. Infrequent spot sampling with, e.g., nets, pumps, or containers, does not reflect the large spatial and temporal variety of MP abundance, and there is little experience with time-integrated, passive sampling methods. However, passive samplers have been applied thoroughly to recover suspended particulate matter (SPM) from water bodies. The physical and chemical characteristics of MP are in range with those of other materials belonging to SPM, and we state that MP are an integral component of SPM. In general, passive samplers like the sedimentation box decrease the flow velocity, enhancing the sedimentation of SPM within the device. The retention rates of particles in sedimentation boxes depend on various factors such as the flow velocity, the SPM size and density, but precise information remains scarce. Therefore, we performed laboratory tests to assess the retention rates of the polymers polystyrene and polyethylene and analyzed the dependency of sedimentation on the flow velocity and particle sizes. The quantification of MP in samples collected by sedimentation boxes underestimates the concentration of smaller-sized particles due to their lower retention rate, and MP concentrations should be reported accordingly. Subsequently, we carried out a series of field experiments with sedimentation boxes and showed that MP can be retained from different water bodies with diverse characteristics. Due to their robust sampling mechanism, sedimentation boxes are promising devices for time-integrated, long-term sampling of MP.

Inputs of plastic impurities into the environment via the application of fertilizers are regulated in Germany and the EU by means of ordinances. Robust and fast analytical methods are the basis of legal regulations. Currently, only macro- and large microplastic contents (>1 mm) are measured. Microplastics (1–1,000 µm), are not yet monitored. Thermal analytical methods are suitable for this purpose, which can determine the mass content and can also be operated fully automatically in routine mode. Thermal extraction desorption-gas chromatography/mass spectrometry (TED-GC/MS) allows the identification of polymers and the determination of mass contents in solid samples from natural environments. In accordance with the German or European Commission (EC) Fertiliser Ordinance, composting plants should be monitored for microplastic particles with this method in the future. In this context a compost plant was sampled. At the end of the rotting process, the compost was sieved and separated in a coarse (>1 mm) and a fine fraction (<1 mm). The fine fraction was processed using density separation comparing NaCl and NaI as possible salt alternative and screened for microplastic masses by TED-GC/MS with additional validation and quality assurance experiments. With TED-GC/MS total microplastics mass contents of 1.1–3.0 μg/mg in finished compost could be detected with polyethylene mainly. What differs much to the total mass of plastics in the coarse fraction with up to 60 μg/mg, which were visually searched, identified via ATR-FTIR and gravimetrically weighted.

In this study, carried out within the Joint Danube Survey 4, a comprehensive microplastic screening in the water column within a large European river basin from its source to estuary, including major tributaries, was realized. The objective was to develop principles of a systematic and practicable microplastic monitoring strategy using sedimentation boxes for collection of suspended particulate matter followed by its subsequent analysis using thermal extraction desorption-gas chromatography/mass spectrometry. In total, 18 sampling sites in the Danube River Basin were investigated. The obtained suspended particulate matter samples were subdivided into the fractions of >100 mu m and <100 mu m and subsequently analyzed for microplastic mass contents. The results showed that microplastics were detected in all samples, with polyethylene being the predominant polymer with maximum contents of 22.24 mu g/mg, 3.23 mu g/mg for polystyrene, 1.03 mu g/mg for styrene-butadiene-rubber, and 0.45 mu g/mg for polypropylene. Further, polymers such as different sorts of polyester, polyacrylates, polylactide, and natural rubber were not detected or below the detection limit. Additional investigations on possible interference of polyethylene signals by algae-derived fatty acids were assessed. In the context of targeted monitoring, repeated measurements provide more certainty in the interpretation of the results for the individual sites. Nevertheless, it can be stated that the chosen approach using an integrative sampling and determination of total plastic content proved to be successful.

An investigation of microplastic (MP) occurrence in a municipal wastewater treatment plant (WWTP) effluent with tertiary treatment was carried out. Representative sample volumes of 1 m3 were taken by applying a fractionated filtration method (500, 100, and 50 µm mesh sizes). The detection of MP mass fractions by thermal extraction desorption–gas chromatography/mass spectrometry (TED-GC/MS) was achieved without the previously required additional sample pretreatment for the first time. Different types of quantification methods for the evaluation of TED-GC/MS data were tested, and their accuracy and feasibility have been proven for real samples. Polyethylene, polystyrene, and polypropylene were identified in effluent samples. The polymer mass content varied significantly between 5 and 50 mg m−3. A correlation between the MP load and the quantity of suspended matter in the WWTP effluents, particle size distribution, particle type, and operation day (i.e., weekday, season, and capacity) was not found. It can be concluded that a meaningful assessment of WWTPs requires a comprehensive sampling campaign with varying operation conditions.

Anthropogenic organohalogens (AOHs) are toxic and persistent pollutants that occur ubiquitously in the environment. An unneglectable portion of them can convert into nonextractable residues (NER) in the natural solid substances. NER-AOHs are not detectable by conventional solvent-extraction, and will get remobilized through changes of surrounding environment. Consequently, the formation and fate of NER-AOHs should be investigated comprehensively. In this study, solvent extraction, sequential chemical degradation and thermochemolysis were applied on different sample matrices (sediments, soils and groundwater sludge, collected from industrial areas) to release extractable and nonextractable AOHs. Covalent linkages were observed most favorable for the hydrophilic-group-containing monocyclic aromatic AOHs (HiMcAr-AOHs) (e.g. halogenated phenols, benzoic acids and anilines) incorporating into the natural organic matter (NOM) as NER. Physical entrapment mainly contributed to the NER formation of hydrophobic monocyclic aromatic AOHs (HoMcAr-AOHs) and polycyclic aromatic AOHs (PcAr-AOHs). The hypothesized remobilization potential of these NER-AOHs follow the order HiMcAr-AOHs > HoMcAr-AOHs/ aliphatic AOHs > PcAr-AOHs. In addition, the NOM macromolecular structures of the studied samples were analyzed. Based on the derived results, a conceptual model of the formation mechanisms of NER-AOHs is proposed. This model provides basic molecular insights that are of high value for risk assessment and remediation of AOHs.

Nonextractable residues (NER) are pollutants incorporated into the matrix of natural solid matter via different binding mechanisms. They can become bioavailable or remobilize during physical chemical changes of the surrounding conditions and should thus not be neglected in environmental risk assessment. Sediments, soils, and ground-water sludge contaminated with DDXs (DDT, dichlorodiphenyltrichloroethane; and its metabolites) were treated with solvent extraction, sequential chemical degradation, and thermochemolysis to study the fate of NER-DDX along different environmental aquatic-terrestrial pathways. The results showed that DDT and its first degradation products, DDD (dichlorodiphenyldichloroethane) and DDE (dichlorodiphenyldichloroethylene), were dominant in the free extractable fraction, whereas DDM (dichlorodiphenylmethane), DBP (dichlorobenzophenone), and DDA (dichlorodiphenylacetic-acid) were observed primarily after chemical degradation. The detection of DDA, DDMUBr (bis(p-chlorophenyl)-bromoethylene), DDPU (bis(p-chloropheny1)-propene) and DDPS (bis(p-chlorophenyl)-propane) after chemical treatments evidenced the covalent bindings between these DDXs and the organic matrix. The identified NER-DDXs were categorized into three groups according to the three-step degradation process of DDT. Their distribution along the different pathways demonstrated significant specificity. Based on the obtained results, a conceptual model of the fate of NER-DDXs on their different environmental aquatic-terrestrial pathways is proposed. This model provides basic knowledge. for risk assessment and remediation of both extractable and nonextractable DDT-related contaminations.

The pesticide p,p'-DDT (1-chloro-4-[2,2,2-trichloro-1-(4-chlorophenyl) ethyl]benzene) has been used in agriculture, forestry, and vector control for decades. Technical DDT, the purity commonly used for insecticidal applications, contained p,p'-DDT as well as its constitution isomer o,p'-DDT (1-chloro-2-(2,2,2-trichloro-1-(4-chlorophenyl)ethyl] benzene) and several closely related compounds. To investigate the effect of environmental processes on the isomer-specific composition of DDT and its degradation products, we examined previously published and newly acquired quantitative data with regard to o,p'-/p,p'-DDX ratios in different environmental matrices. Isomeric shifts related to the depositional regime, transfer between and within compartments, and microbial transformation were clearly observed. Shifts of the positional isomer ratios potentially can serve as indictors to track the environmental fate of DDX. For an unambiguous assignment of these shifts to specific processes, further systematic studies and complementary lab experiments are necessary.

The pesticide DDT (1-chloro-4-[2,2,2-trichloro-1-(4-chlorophenyl)ethyl]benzene) and its degradates are among the most persistent and abundant organochlorine contaminates in the environment, and DDT is still being produced in several Asian countries. In this study, we report for the first time on the detection of DDT-related compounds with one additional or missing chlorine atom at the phenyl group (DDX±Cl) in sediment and soil samples taken in the vicinity of former and current DDT production sites. These congeneric compounds most likely originate from production residues disposed of into the environment. In order to ensure an adequate identification and quantification of this novel organic pollutant group, individual DDX±Cl were synthesized as reference compounds by simulating an impure production of DDT in the laboratory. In contrast to DDX±Cl with (chloro)alkyl moieties, DDX±Cl with (chloro)alkenyl moieties cannot be unambiguous assigned by gas-chromatographic/mass spectrometric (GC/MS) fragmentation and elution orders. The occurrence of DDX±Cl in environmental samples allows to draw conclusions about the purity of the production process in the associated production sites. Moreover, they potentially can serve as molecular indicators to differentiate between industrial DDT emissions and insecticidal applications of DDT. This hypothesis has yet to be confirmed by further research.

A harmonization of sampling, sample preparation and detection is pivotal in order to obtain comparable data on microplastics (MP) in the environment. This paper develops and proposes a suitable sampling concept for waterbodies that considers different plastic specific properties and influencing factors in the environment. Both artificial water including defined MP fractions and the discharge of a wastewater treatment plant were used to verify the derived sampling procedure, sample preparation and the subsequent analysis of MP using thermal extraction-desorption gas chromatography - mass spectrometry (TED-GC-MS). A major finding of this paper is that an application of various particle size classes greatly improves the practical handling of the sampling equipment. Size classes also enable the TED-GC-MS to provide any data on the MP size distribution, a substantial sampling property affecting both the necessary sampling volume and the optimal sampling depth. In the artificial water with defined MP fractions, the recovery rates ranged from 80 to 110%, depending on the different MP types and MP size classes. In the treated wastewater, we found both polyethylene and polystyrene in different size classes and quantities.

The brominated flame retardant hexabromocyclododecane (HBCD) was monitored in fish and sediment (from one lake) or suspended particulate matter (SPM; from five rivers) at European freshwater sites to study the effects of reduction measures implemented by HBCD producers and users in recent years. Bream (Abramis brama) were sampled annually between 2007 and 2013 in the rivers Götaälv/SE, Rhône/FR, Western Scheldt/NL, Mersey/UK, and Tees/UK and in Lake Belau/DE. Sediment/SPM was taken every second year between 2008 and 2014. HBCD was analyzed by LC/MS/MS allowing the determination of the alpha-, beta-, and gamma-diastereomers. For most sites, a decrease in ∑HBCD was observed in fish (e.g., in the Rhône and Western Scheldt by about 80 and 60%, respectively, with significantly decreasing trends, p < 0.01). In the Rhône, HBCD also decreased in SPM. At the sampling site in the Tees which was impacted by a former HBCD point source, fish HBCD levels decreased only after a major flood event in 2013. While fish data indicate a decline in environmental HBCD concentrations at most sites with diffuse emissions, SPM data were less conclusive. The European environmental quality standard for HBCD in fish of 167 μg kg−1 wet weight was met by all fish samples in 2013.

Side and initial degradation products of the persistent organic pollutant hexachlorocyclohexane (HCH) were largely neglected in environmental analysis so far. However, these compounds can be indicative for biodegradation or emission sources.Thus, several samples from a contaminated riverine system in vicinity to a former HCH production site in Central Germany were analyzed. This area adjacent to the industrial megasite Bitterfeld-Wolfen is known for elevated concentrations of various organic industrial pollutants as legacy of decades of industrial activity and subsequent deposition of chemical waste and emission of waste effluents. In environmental compartments of this riverine system, several isomers of HCH related compounds were detected comprising the two lower chlorinated species tetrachlorocyclohexene (TeCCH) and pentachlorocyclohexene (PeCCH) and the higher chlorinated species heptachlorocyclohexane (HpCCH). Except for the uppermost soil of an analyzed riparian wetland, concentrations of these compounds were low. Detected isomers in sediment, water, and soil samples correlated and dominant isomers of PeCCH and HpCCH were observed in the alluvial deposits. Comparisons with industrial HCH waste revealed isomeric patterns similar to patterns found in soil samples. Therefore, the application of HpCCH as an indicator of industrial HCH pollution is suggested.

Various factors influence the isomeric composition of hexachlorocyclohexanes which are released to the environment. Original compositions in technical mixtures may vary slightly, but higher shifts are observable for transfer processes, bioaccumulation and microbial transformation. Consequently, the isomeric composition in environmental samples is a superposition of these processes. In this study, isomeric distributions and concentrations of hexachlorocyclohexanes were analyzed in water, sediment, and soil samples of a riverine system known to be highly contaminated by hexachlorocyclohexanes. To assess desorption of hexachlorocyclohexanes from particulate matter to water, batch shaking and percolation experiments were conducted complementary. Analyzed samples exhibited total hexachlorocyclohexane concentrations of up to 2.8 µg/g in sediments and up to 21 µg/L in river water predominated by the α-isomer. Downstream hexachlorocyclohexane pattern changed toward δ-isomer domination, while overall hexachlorocyclohexane concentrations decreased. Desorption experiments supported the assumption of discrimination by preferred association of the α- and β-isomers with particulate matter, showing elevated mobilization of γ-, δ- and ε-hexachlorocyclohexanes and lower mobilization of the α- and β-isomers. Soil samples of a riparian wetland exhibited elevated concentrations of hexachlorocyclohexanes exceeding 200 µg/g and predominance of α-hexachlorocyclohexanes in the top soil layer. Subjacent soil layers showed rapidly decreasing hexachlorocyclohexane concentrations and an isomeric shift toward the β-isomer. The assumed preferential mobilization of β-hexachlorocyclohexane was supported by desorption experiments. This study demonstrated firstly that transfer processes influence substantially hexachlorocyclohexane isomer distribution in the aquatic environment. Secondly, conditions of aging determine strength of association and remobilization potential of hexachlorocyclohexane residue down to an isomer-specific level.

Cadmium, lead, mercury, copper, nickel, zinc, and arsenic were analyzed in suspended particulate matter (SPM), zebra mussels, and bream sampled yearly under the program of the German Environmental Specimen Bank (ESB) in the rivers Rhine, Elbe, Danube, Saar, Mulde, and Saale and in Lake Belau. Temporal and spatial trends were analyzed, correlations between metal levels in different specimen types assessed, and sampling sites ranked according to their metal levels by calculating a Multi-Metal Index (MMI) for every specimen type and site. SPM: Highest metal loads were detected in Mulde, Saale, and Elbe right downstream of the Saale confluence. In the Elbe, metal loads in SPM were mostly highest in the upper and middle section of the river while in Rhine and Saar concentrations increased downstream. Temporal trends since 2005 were detected only at three sites. Zebra mussel: MMIs were highest in the tidal section of the Elbe and the lower Rhine and lowest in Lake Belau and the upper Danube. Different temporal trends were detected since the early 1990s depending on site and metal. Bream: As, Pb, Cu, and Hg were analyzed in muscle tissue and Pb, Cd, Cu, and Zn in liver. For both tissues, MMIs were highest in Mulde and Saale and the lower and middle Elbe. Since the early 1990s, Hg, Pb, and Cu decreased in bream muscle at many sites while As increased at 6 of the 17 sites. The findings indicate that Hg, Pb, and Cu have obviously decreased in many freshwater ecosystems in recent years, whereas As and Ni levels have increased at several sites. Metal levels and temporal trends mostly differed between the specimen types under investigation and only few correlations between specimen types were detected. This underlines the importance of including different components of an ecosystem when assessing its environmental quality.

A retrospective monitoring of triclosan (TCS; period 1994-2003 and 2008) and its potential transformation product methyl-triclosan (MTCS; period 1994-2008) was performed using archived fish samples from German rivers (16 sites, including Elbe and Rhine). At four of these sites suspended particulate matter (SPM) was also investigated covering the period 2005-2007. Samples were analyzed by GC/MS, either directly (MTCS) or after derivatization (TCS). TCS burdens of fish muscle tissue ranged from <0.2-3.4 ng g(-1) ww (wet weight; corresponding to <2-69 ng g(-1) lw, lipid weight) without apparent concentration trends over time. MTCS was detected at considerably higher concentrations in fish ranging from 1.0-33 ng g(-1) ww (47-1010 ng g(-1) lw) and increased until about 2003-2005. Thereafter, concentrations generally were lower, although at some sites single higher values were observed in recent years. In SPM, decreasing MTCS concentrations in the range 1-4 ng g(-1) dry weight were detected while TCS was always below the limit of quantification. Assuming that MTCS concentrations are correlated to TCS consumption, the observed decrease in MTCS levels may be partly a result of the voluntary renunciation of TCS use in detergents for, e.g., laundry or dishwashing declared by a manufacturers' association in 2001. Because of a lack of ecotoxicity studies for MTCS, a QSAR-derived predicted no effect concentration (PNEC) was compared to averaged ambient water concentrations of fish which were calculated from maximum tissue residues by applying an appropriate bioconcentration factor from literature. Since these calculated water concentrations were below the PNEC it is assumed that MTCS alone poses no immediate risk to aquatic organism. The conversion to a PNEC for SPM organisms and comparison with detected SPM levels of MTCS also revealed no risk.

It is known for decades that the isomeric composition of organic pollutants can be influenced substantially by environmental processes such as biotransformation or transfer between compartments. This accounts also for the pesticide 2,2,-bis(4-chlorophenyl)-1,1,1-trichloroethane, better known as p,p′-DDT, and its accompanied substitution isomer 2-(2-chlorophenyl)-2-(4-chlorophenyl)-1,1,1-trichloroethane (o,p′-DDT). Although many studies followed the environmental fate of DDT, only very few publications reported on quantitative data of both o,p′- and p,p′-isomers. Therefore this condensed review describes evidence for remarkable changes and shifts in o,p′-/p,p′-ratios of DDT-related compounds. The application of isomer-specific analysis remains dominantly on emission source apportionment, for example, to differentiate DDT and dicofol emission. Only very few studies linked observed isomer shifts to aspects of environmental processes, such as (1) volatility from soil to air, (2) environmental stability in soil or (3) bioaccumulation in fishes. Additionally, several studies failed to use isomer-specific interpretation in order to obtain more detailed insight into environmental processes, for example, for observed isomer shifts during air–water fluxes. The o,p′-/p,p′-ratios of DDT and its main metabolite DDD have been detected more or less on the same level, whereas the isomers of the second main metabolite DDE were definitely depleted by the o,p′-isomer in all environmental compartments, indicating a general isomer-specific differentiation during DDT metabolism.

The Water Framework Directive (WFD) requires Member States of the European Union to achieve good status of all waters in 2015. The survey of chemical status focuses on checking compliance of the quality of water systems against environmental quality standards and temporal trend monitoring of contaminants in sediments and/or biota.As sediments appropriate for monitoring contaminants may not always be available, we discuss the use of suspended particulate matter (SPM) as an alternative. We describe and discuss differences in quality and quantity of sediments and SPM collected by different sampling techniques with regard to the respective advantages and drawbacks for various monitoring purposes.Often, both contaminant concentrations in sediments and in SPM may give the required information. However, selection of the technique applied for collecting SPM should take into consideration, inter alia, the purpose of the monitoring, as well as the hydrodynamic and morphological conditions of the area monitored. We illustrate general conclusions with field applications from the European rivers Rhine and Elbe. (C) 2012 Elsevier Ltd. All rights reserved.

2,2-bis(chlorophenyl)-1,1,1-trichloroethane (DDT) metabolites, other than those routinely measured [i.e., 2,2-bis(chlorophenyl)-1,1-dichloroethylene (DDE) and 2,2-bis(chlorophenyl)-1,1-dichloroethane (DDD)], have recently been detected in elevated concentrations not only in the surface water of Teltow Canal, Berlin, but also in sediment samples from Elbe tributaries (e.g., Mulde and Havel/Spree). This was paralleled by recent reports that multiple other metabolites could emerge from the degradation of parent DDT by naturally occurring organisms or by interaction with some heavy metals. Nevertheless, only very few data on the biological activities of these metabolites are available to date. The objective of this communication is to evaluate, for the first time, the cytotoxicity, dioxin-like activity, and estrogenicity of the least-studied DDT metabolites.

It is known for decades that isomeric composition of organic pollutants can be influenced substantially by environmental processes such as biotransformation or transfer between compartments. This accounts also for the pesticide 2,2,-bis(4-chlorophenyl)-1,1,1-trichlorethane, better known as p,p′-DDT, and its accompanied substitution isomer 2-(2-chlorophenyl)-2-(4-chlorophenyl)-1,1,1-trichlorethane (o,p′-DDT). Therefore, for this literature review over 2000 recent literature citations were checked for information on the isomer ratios of DDT and its metabolites in the environment. Although many studies followed the environmental fate of DDT, only very few publications reported on quantitative data of both o,p′- and p,p′-isomers. However, this review revealed evidence for remarkable changes and shifts in o,p′-/p,p′-ratios of DDX. The application of isomer specific analysis remains dominantly on emission source apportionment, e.g. to differentiate DDT and dicofol emission.Only very few studies linked observed isomer shifts to aspects of environmental processes, such as (i) volatility from soil to air, (ii) environmental stability in soil or (iii) bioaccumulation in fishes. Additionally, several studies failed to use isomer specific interpretation in order to obtain more detailed insight into environmental processes e.g. for observed isomer shifts during air-water fluxes.Evaluating the comprehensive data set presented in this review a clear discrimination of o,p′-/p,p′-ratios of DDT, DDD and DDE is evident. The o,p′-/p,p′-ratios of DDT and DDD have been detected more or less on the same level, whereas the isomers of DDE were definitely depleted by the o,p′-isomer in all environmental compartments. This observation indicates a general isomer-specific differentiation during DDT metabolism.Finally, the potential to follow the environmental fate of DDX via the isomer composition has not been realized accurately so far, and, consequently, has not been well established in the field of environmental chemistry yet.

BACKGROUND, AIM, AND SCOPE:Building up a comprehensive accurate monitoring program requires the knowledge on the contamination in principal, complemented by detailed information on individual contaminants. The selection of pollutants to be considered in monitoring actions is based dominantly on the information available about their environmental relevance (e.g., persistence, bioaccumulation potential, toxicological and ecotoxicological properties) and their occurrence within the affected environmental system. Therefore, this study focused on the identification of organic contaminants in selected German and European rivers to demonstrate the usefulness of a screening approach as complementary base for the compound selection process within monitoring activities.MATERIALS AND METHODS:Gas chromatography-mass spectrometry-based screening analyses were performed on five and six samples from German and European rivers, respectively. Identification of individual contaminants was based on the investigation of mass spectral and gas chromatographic properties compared with databases and reference materials.RESULTS:This study summarized the results of non-target screening analyses applied to river water samples and focused dominantly on, so far, unnoticed organic contaminants. Numerous compounds have been identified belonging to the groups of pharmaceuticals, technical additives, pesticides, personal care products, and oxygen-, nitrogen-, and sulfur-containing compounds of obviously anthropogenic origin. They are discussed in terms of their structural properties, their possible application or usage, and the environmental information available so far.DISCUSSION:Generally, two different groups of compounds have been differentiated that might contribute to potential monitoring programs. Firstly, more specific contaminants characterizing the individual riverine systems have been depicted (e.g., 4-chloro-2-(trifluoromethyl)aniline, di-iso-propylurea). The consideration of these substances in monitoring analyses to be applied to the corresponding catchment areas is recommended in order to monitor the real state of pollution. Secondly, contaminants have been introduced that appeared with higher multiplicity throughout the different river systems (e.g., TMDD, TXIB). Since these compounds tend to obviously have an elevated environmental stability accompanied by a widespread distribution, it is recommended to consider them in international high-scale monitoring programs.CONCLUSIONS:For monitoring purposes, a fundamental knowledge on the diversity of pollutants is an important precondition, which can be supported by screening analyses. Obviously, numerous organic contaminants have been neglected so far in environmental studies on river water, comprising also investigation on potential harmful effects and, therefore, their implementation in monitoring activities has been hindered.RECOMMENDATIONS AND PERSPECTIVES:Therefore, based on the results of this study, screening analyses should be established as principle tools to improve and complement the substance spectra for monitoring purposes. Secondly, scientific efforts should be strengthened to expand our knowledge on actually appearing organic contaminants in riverine systems.