Polybrominated diphenyl ethers (PBDEs) have been widely used as flame retardants in concentrations up to 30 w% of the total mass of the products. Worldwide consumption of technically relevant PBDE mixtures was about 7500 tons (penta-BDEs), 3790 tons (octa-BDEs) and 56,100 tons (deca-BDE) in 2001 and about 50–60% of this total volume was discharged into environment only by agricultural use of sewage sludges. The use of PBDEs was strictly regulated from 2004 onwards due to their high emission load and their effect as endocrine disrupters, neurotoxins, and fertility reducing agents. Nevertheless, soils worldwide are contaminated by gaseous and particle-bound transport of PBDEs. Therefore, the uptake of PBDEs from contaminated agricultural land via crops and the food chain is a major human exposure pathway. However, uptake and intrinsic transport behavior strongly depend on crop specifics and various soil parameters. The relevant exposure and transformation pathways, transport-relevant soil and plant characteristics and both root concentration factor (RCF) and transfer factor (TF) as derivable parameters are addressed and quantified in this chapter. Finally, based on available crop specific data a general statement about the transport behavior of PBDEs in twelve different crops according to relevant PBDE congeners is given.

The parameter total suspended solids (TSS) is often used to evaluate the need for stormwater treatment or to assess the effectiveness of treatment measures. The purpose of this study is to analyze the value and the limitations of this approach using metals as an example. They are of major concern due to their accumulating effects in the environment. Data of a monitoring campaign at a stormwater treatment facility is evaluated. TSS, organic matter and the associated metals (Cr, Cu, Zn, Cd, and Pb) were analyzed in four different particle size fractions (<63 µm, 63–125 µm, 125–250 µm, and 250–2000 µm). While the highest event meant concentrations for all metals were found in the smallest fraction, a rather uniform particulate bound metal concentration (mass of metal per mass of particulate matter) over the first three particle size fractions was detected. Total metal loads correlated well with TSS even better with TSS < 63 µm. However, the removal efficiency in terms of the reduction of the total metal load was not reflected sufficiently by the TSS or TSS < 63 µm removal efficiency.

Road-deposited sediments (RDS) contain metals that can pollute receiving waters during precipitation events. The concentration of particle-bound metals tends to increase with decreasing particle size. In terms of metal load, the highest loads were often located in the medium range of particle sizes. Many studies have used varying or undocumented sieving techniques without showing the quality of the separation process. This is important as different particle size classes are documented with different pollution contents and loads. This knowledge builds the foundation for the selection of best management practices to improve receiving water quality. Based on the knowledge that the separation of particle sizes by the commonly applied dry sieving can be methodologically biased, this study compares particle size classes obtained by dry and wet sieving methods. The aim of the study was to show the methodological influence of the sieving process on the particle-size distribution (PSD) with focus on the metal distribution within RDS. Therefore, concentrations of Cu, Zn and Pb were determined and loads were calculated per sieve fraction after wet and dry sieving. Wet sieving causes a shift of the PSD to finer particles and both metal concentrations and loads are significantly higher especially in the smallest sieve fractions. Fine, highly polluted particles remained in coarser sieve fractions after dry sieving. This leads to diverging metal contents and especially loads in the fractions > 250 µm and thus lead to varying conclusions from the results. The results of the comparison of sieving methods however confirmed the relevance of the fine particle fractions in terms of best management practices. The fraction < 40 µm showed highest concentration and load in RDS after wet sieving. The results also showed the considerable influence of the sieving method used and the need to document laboratory methods as part of good laboratory practice.

Polybrominated diphenyl ethers (PBDEs) have widely been used for decades as flame retardants in a variety of products like plastics for building insulation, upholstered furniture, electrical appliances, vehicles, aircrafts, polyurethane foams, textiles, cable insulation, appliance plugs and various technical plastics in concentrations of 5–30%. However, PBDEs also act as endocrine disrupters, neurotoxins, and negatively affect fertility. In 2001, worldwide consumption of technically relevant penta-BDEs was still estimated at 7500 tons, octa-BDEs at 3790 tons, and deca-BDE at 56,100 tons, but 50–60% of this total volume are discharged into the environment via sewage sludge and its agricultural use alone. In addition, soils are ubiquitously contaminated by the gaseous or particle-bound transport of PBDEs, which today has its main source in highly contaminated electronic waste recycling sites. The emitted PBDEs enter the food chain via uptake by the plants’ roots and shoots. However, uptake and intrinsic transport behaviour strongly depend on crop specifics and various soil parameters. The relevant exposure and transformation pathways, transport-relevant soil and plant characteristics and both root concentration factors (RCF) and transfer factors (TF) as derivable parameters are addressed and quantified in this review. Finally, a simple predictive model for quantification of RCF and TF based on log K OW values and the organic content of the soil/lipid content of the plants is also presented.

Wastewater treatment plants are known as major sources for the release of micropollutants and bacteria into surface waters. To reduce this contaminant and microbial input, new technologies for effluent treatment have become available. The present paper reports the chemical, microbiological, biochemical, and biological effects of upgrading a wastewater treatment plant (WWTP) with a powdered activated carbon stage in the catchment area of the Schussen River, the largest German tributary of Lake Constance. Data were obtained prior to and after the upgrade between 2011 and 2017. After the upgrading, the release of antibiotic resistant and non-resistant bacteria, micropollutants, and their effect potentials was significantly lower in the effluent. In addition, in the Schussen River downstream of the wastewater treatment plant, reduced concentrations of micropollutants were accompanied by both a significantly improved health of fish and invertebrates, along with a better condition of the macrozoobenthic community. The present study clearly provides evidence for the causality between a WWTP upgrade by powdered activated carbon and ecosystem improvement and demonstrates the promptness of positive ecological changes in response to such action. The outcome of this study urgently advocates an investment in further wastewater treatment as a basis for decreasing the release of micropollutants and both resistant and non-resistant bacteria into receiving water bodies and, as a consequence, to sustainably protect river ecosystem health and drinking water resources for mankind in the future.

This work investigates the influence of ammonium ions and the organic load (chemical oxygen demand (COD)) on the UV/chlorine AOP regarding the maintenance of free available chlorine (FAC) and elimination of 16 emerging contaminants (ECs) from wastewater treatment plant effluent (WWTE) at pilot scale (UV chamber at 0.4 kW). COD inhibited the FAC maintenance in the UV chamber influent at a ratio of 0.16 mg FAC per mg COD (kHOCl–COD = 182 M−1s−1). An increase in ammonium ion concentration led to a stoichiometric decrease of the FAC concentration in the UV chamber influent. Especially in cold seasons due to insufficient nitrification, the ammonium ion concentration in WWTE can become so high that it becomes impossible to achieve sufficiently high FAC concentrations in the UV chamber influent. For all ECs, the elimination effect by the UV/combined Cl2 AOP (UV/CC) was not significantly higher than that by sole UV treatment. Accordingly, the UV/chlorine AOP is very sensitive and loses its effectiveness drastically as soon as there is no FAC but only CC in the UV chamber influent. Therefore, within the electrical energy consumption range tested (0.13–1 kWh/m3), a stable EC elimination performance of the UV/chlorine AOP cannot be maintained throughout the year.

Effluent of a municipal wastewater treatment plant (WWTP) was treated on-site with the UV/chlorine (UV/HOCl) advanced oxidation process (AOP) using a pilot plant equipped with a medium pressure UV lamp with an adjustable performance of up to 1 kW. Results obtained from parallel experiments with the same pilot plant, where the state of the art UV/H2O2 AOP was applied, were compared regarding the removal of emerging contaminants (EC) and the formation of adsorbable organohalogens (AOX). Furthermore, the total estrogenic activity was measured in samples treated with the UV/chlorine AOP. At an energy consumption of 0.4 kWh/m3 (0.4 kW, 1 m3/h) and in a range of oxidant concentrations from 1 to 6 mg/L, the UV/chlorine AOP had a significantly higher EC removal yield than the UV/H2O2 AOP. With free available chlorine concentrations (FAC) in the UV chamber influent of at least 5 mg/L (11 mg/L of dosed Cl2), the total estrogenic activity could be reduced by at least 97%. To achieve a certain concentration of FAC in the UV chamber influent, double to triple the amount of dosed Cl2 was needed, resulting in AOX concentrations of up to 520 µg/L.

Background The present work investigates the impact of discharges from a storm water sedimentation basin (SSB) receiving runoff from a connected motorway in southern Germany. The study lasted for almost two years and was aimed at assessing the impact of the SSB on the fauna of the Argen River, which is a tributary of Lake Constance. Two sampling sites were examined up- and downstream of the SSB effluent. A combination of different diagnostic methods (fish embryo test with the zebrafish, histopathology, micronucleus test) was applied to investigate health impairment and genotoxic effects in indigenous fish as well as embryotoxic potentials in surface water and sediment samples of the Argen River, respectively, in samples of the SSB effluent. In addition, sediment samples from the Argen River and tissues of indigenous fish were used for chemical analyses of 33 frequently occurring pollutants by means of gas chromatography. Furthermore, the integrity of the macrozoobenthos community and the fish population were examined at both investigated sampling sites. Results The chemical analyses revealed a toxic burden with trace substances (originating from traffic and waste water) in fish and sediments from both sampling sites. Fish embryo tests with native sediment and surface water samples resulted in various embryotoxic effects in exposed zebrafish embryos (Fig. 1 ). In addition, the health condition of the investigated fish species (e.g., severe alterations in the liver and kidney) provided clear evidence of water contamination at both Argen River sites (Fig. 2 ). At distinct points in time, some parameters (fish development, kidney and liver histopathology) indicated stronger effects at the sampling site downstream of the SSB effluent than at the upstream site. Conclusions Our results clearly showed that the SSB cannot be assigned as the main source of pollutants that are released into the investigated Argen River section. Moreover, we showed that there is moderate background pollution with substances originating from waste waters and traffic which still should be taken seriously, particularly with regard to the impairment of fish health at both investigated field sites. Since the Argen is a tributary of Lake Constance, our results call for a management plan to ensure and improve the river’s ecological stability.

In der aquatischen Umwelt werden – nicht zuletzt auch wegen der immer emp ndlicher werdenden instrumentellen Analytik – immer mehr anthropogene organische Mikroverunreinigungen nachgewiesen. Das Spektrum dieser Substanzen reicht von pharmazeutischen Wirksto en über Weichmacher und Flammschutzmittel bis hin zu synthetischen Du sto en, Korrosionsschutzmitteln, Süßsto en und Pestiziden. Toxikologische und ökotoxikologische Aspekte der einzelnen Substanzen und ihre E ekte bei den in der Umwelt vorkommenden Konzentrationsbereichen sind nur in den wenigsten Fällen bekannt. Dies gilt umso mehr für mögliche chronische E ekte oder die Wirkungen des Gesamtcocktails. Dennoch werden aus Vorsorgegründen Maßnahmen zur Verringerung des Umwelteintrags angestrebt und umgesetzt. Eine Verringerung des Sto eintrags in die Umwelt kann prinzipiell über die Quellenvermeidung (Verbot oder Ersatz von Substanzen), dezentrale Ansätze (z.B. separate Behandlung von Krankenhausabwässern) und end of pipe-Ansätze (z.B. Einsatz weitergehender Abwassereinigungstechnologien in kommunalen Kläranlagen) erfolgen. Die Kenntnis von Eintragsarten, Eintragsmengen, Transportund Umweltverhalten ist allerdings eine Grundvoraussetzung für die Einleitung zielgerichteter und – auch in ökonomischer Hinsicht – e ektiver Maßnahmen zur weitergehenden Elimination organischer Mikroverunreinigungen. Auf Grund ihrer unterschiedlichen Anwendungsbereiche und Anwendungsarten gelangen die Substanzen über verschiedene Eintragspfade in die Umwelt. Die individuellen chemisch-physikalischen Eigenscha en der Substanzen sind dafür verantwortlich, ob sie in partikelgebundener Form oder ausschließlich in Wasser gelöst transportiert werden. Dieses unterschiedliche Transportverhalten entscheidet letztendlich über den Verbleib der Substanzen und die Ansätze zu ihrer Elimination. Ebenso von Bedeutung ist, ob die Mikroverunreinigungen persistent oder biologisch abbaubar sind oder auf Grund des kontinuierlichen Eintrags in die Umwelt trotz ihrer Abbaubarkeit als quasi-persistent zu bezeichnen sind. Bezüglich der Ertüchtigung kommunaler Kläranlagen, die in diesem Falle als Punktquellen für abwasserbürtige organische Mikroverunreinigungen wie z.B. pharmazeutische Wirksto e zu de nieren sind, entscheidet das über die chemischphysikalischen Eigenscha en der Substanzen festgelegte Verhalten darüber, ob eine Elimination durch Verbesserung der Partikelabtrennung oder – bei wassergelösten und wenig abbaubaren Verbindungen – weitergehende Maßnahmen wie z.B. der Einsatz von Pulveraktivkohle oder von Ozon notwendig werden. Als problematisch erweist sich die Erfassung und Behandlung von Sto en unterschiedlicher Eintragspfade in die aquatische Umwelt. Als Extremfall zählen hier die diffusen Einträge persistierender Mikroverunreinigungen wie z.B. polycyclische aromatische Kohlenwasserstoffe (PAK), die bei unvollständigen Verbrennungsprozessen gebildet werden und in partikelgebundener Form transportiert werden. Für diese gesetzlich regulierten Verbindungen – Vertreter sind in der Liste der prioritären Stoffe der EU-Wasserrahmenrichtlinie aufgeführt und mit Umweltqualitätsnormen belegt [1] – können für Ober ächengewässer (teil)-e ektive Maßnahmen nur an Entlastungsbauwerken ansetzen, die bei Mischwasserentlastungen eine wesentliche Quelle für diese Substanzen darstellen. Der Eintrag in Ober ächengewässer über gereinigte kommunale Abwässer ist für PAK von untergeordneter Bedeutung. Landwirtscha lich eingesetzte Pestizide wiederum sind anwendungsbedingt einer anderen Transportebene zuzuordnen und stellen auf Grund der teilweise extremen Saisonalität ihres Au retens andere Anforderungen für eine gezielte Reduktion ihres Umwelteintrags. Grundlage für die Bewertung einer Belastungssituation mit organischen Mikroverunreinigungen sind vorhandene Messdaten. Bislang werden Mikroverunreinigungen meist nur sporadisch im Rahmen von bestenfalls wenigen Stichproben pro Jahr und nur an wenigen Gewässerstellen untersucht und daraus Aussagen zur Belastung des Gewässers abgeleitet. Gemäß Ober ächengewässerverordnung [2] sind für zahlreiche Substanzen Jahresmittelwerte einzuhalten. Daher ist die Monitoringstrategie (Probennahmeorte, Art der Probennahme, Probennahmeintervalle) bedeutsam für die aus Messergebnissen ableitbare Aussage und die Bewertung von Eintragspfaden.

Increasing numbers of organic micropollutants are emitted into rivers via municipal wastewaters. Due to their persistence many pollutants pass wastewater treatment plants without substantial removal. Transport and fate of pollutants in receiving waters and export to downstream ecosystems is not well understood. In particular, a better knowledge of processes governing their environmental behavior is needed. Although a lot of data are available concerning the ubiquitous presence of micropollutants in rivers, accurate data on transport and removal rates are lacking. In this paper, a mass balance approach is presented, which is based on the Lagrangian sampling scheme, but extended to account for precise transport velocities and mixing along river stretches. The calculated mass balances allow accurate quantification of pollutants' reactivity along river segments. This is demonstrated for representative members of important groups of micropollutants, e.g. pharmaceuticals, musk fragrances, flame retardants, and pesticides. A model-aided analysis of the measured data series gives insight into the temporal dynamics of removal processes. The occurrence of different removal mechanisms such as photooxidation, microbial degradation, and volatilization is discussed. The results demonstrate, that removal processes are highly variable in time and space and this has to be considered for future studies. The high precision sampling scheme presented could be a powerful tool for quantifying removal processes under different boundary conditions and in river segments with contrasting properties.

In the present study, Polycyclic Aromatic Hydrocarbons (PAHs) and Methoxyphenols (MPs) emitted from the low temperature oxidation of the waste wood samples were identified in the laboratory scale small burning system. Four types of waste wood including untreated hardwood (HW), untreated softwood (SW), treated roof material (RM) and treated window frame (WF) were examined during the experiments. XAD-2 adsorbent tubes were used for sampling of the gaseous combustion products. After extraction of the sample tubes, extracts were analyzed by using the Hewlett Packard 6890 GC coupled with Agilent 5971 Mass Selective (MS) Detector. The relative average contributions of the naphthalene, acenaphthylene and retene in hardwood samples were found higher than those measured in softwood. On the contrary, the relative average contribution of the phenanthrene, anthracene, fluoranthene, benzo(a)anthracene, chrysene and benzo(b)fluoranthene to the total PAH concentration in softwood samples were obtained higher as compared to hardwood sample. Syringol, 4-methyl syringol, 4 methyl guaiacol, eugenol, properlysyringol, 4-ethylsyringol, syringylacetone and iso-eugenol were found to be most abundant compounds in the hardwood samples. On the other hand, the most observed compounds in the softwood samples were 4-methylguacicol, iso-eugenol, guaiacol, eugenol and vanillin.

The polycyclic musks tonalide® (acetyl hexamethyltetraline = 1-(3,5,5,6,8,8-hexamethyl-6,7-dihydronaphthalen-2-yl)ethanone, AHTN), galaxolide® (1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta(g)-2-benzopyrane, HHCB) and the degradation product HHCB-lactone were determined in water samples and brown trouts (Salmo trutta fario) of the river Ammer, a small catchment in the state of Baden-Württemberg, south-west Germany. The Ammer receives the effluent discharge of two municipal wastewater treatment plants (WWTPs) with 90,000 population equivalents. The wastewater contributes 14% of the total discharge of the river (average 1.0 m3/s). Water samples were collected monthly at 12 sampling points from June 2010 to May 2011. Downstream the WWTPs the median concentrations of HHCB, AHTN and HHCB-lactone were 0.26 μg/L, 0.06 μg/L and 1.0 μg/L, respectively. The effluent of the WWTPs was identified as main source of the synthetic musks in the surface water. The ratio of HHCB-lactone/HHCB showed significant seasonal variations indicating the influence of the water temperature on the degradation of HHCB in the surface water. A total of 251 trout was caught in two campaigns in October 2010 at 12 sampling points. The median concentrations of HHCB and AHTN in the trouts downstream the WWTPs significantly increased to 10.8 μg/g lipid weight (LW) and 3.7 μg/g LW, respectively.

The present work describes a field survey aiming at assessing the impact of a sewage treatment plant (STP) effluent on fish health by means of biomarkers. Indigenous fish were absent downstream of the STP. To elucidate the reason behind this, brown trout (Salmo trutta f. fario) were exposed in floating steel cages up- and downstream of a STP located at the Neckar River near Tübingen (Southern Germany), for 10 and 30 days. A combination of biomarker methods (histopathological investigations, analysis of the stress protein Hsp70, micronucleus test, B-esterase assays) offered the possibility to investigate endocrine, geno-, proteo- and neurotoxic effects in fish organs. Biological results were complemented with chemical analyses on 20 accumulative substances in fish tissue. Even after short-term exposure, biomarkers revealed clear evidence of water contamination at both Neckar River sites; however, physiological responses of caged brown trout were more severe downstream of the STP. According to this, similar bioaccumulation levels (low μg/kg range) of DDE and 12 polycyclic aromatic hydrocarbons (PAHs) were detected at both sampling sites, while up to fourfold higher concentrations of four PAHs, methyl-triclosan and two synthetic musks occurred in the tissues of downstream-exposed fish. The results obtained in this study suggest a constitutive background pollution at both sites investigated at the Neckar River and provided evidence for the additional negative impact of the STP Tübingen on water quality and the health condition of fish.

Many studies about endocrine pollution in the aquatic environment reveal changes in the reproduction system of biota. We analysed endocrine activities in two rivers in Southern Germany using three approaches: (1) chemical analyses, (2) in vitro bioassays, and (3) in vivo investigations in fish and snails. Chemical analyses were based on gas chromatography coupled with mass spectrometry. For in vitro analyses of endocrine potentials in water, sediment, and waste water samples, we used the E-screen assay (human breast cancer cells MCF-7) and reporter gene assays (human cell line HeLa-9903 and MDA-kb2). In addition, we performed reproduction tests with the freshwater mudsnail Potamopyrgus antipodarum to analyse water and sediment samples. We exposed juvenile brown trout (Salmo trutta f. fario) to water downstream of a wastewater outfall (Schussen River) or to water from a reference site (Argen River) to investigate the vitellogenin production. Furthermore, two feral fish species, chub (Leuciscus cephalus) and spirlin (Alburnoides bipunctatus), were caught in both rivers to determine their gonadal maturity and the gonadosomatic index. Chemical analyses provided only little information about endocrine active substances, whereas the in vitro assays revealed endocrine potentials in most of the samples. In addition to endocrine potentials, we also observed toxic potentials (E-screen/reproduction test) in waste water samples, which could interfere with and camouflage endocrine effects. The results of our in vivo tests were mostly in line with the results of the in vitro assays and revealed a consistent reproduction-disrupting (reproduction tests) and an occasional endocrine action (vitellogenin levels) in both investigated rivers, with more pronounced effects for the Schussen river (e.g. a lower gonadosomatic index). We were able to show that biological in vitro assays for endocrine potentials in natural stream water reasonably reflect reproduction and endocrine disruption observed in snails and field-exposed fish, respectively.

The purpose of this study was to ascertain whether different kinds of underarm deodorants commercially available in Germany might contain substances with estrogenic potential which after use enter the aquatic environment via wastewater. Twenty five deodorants produced by ten different manufacturers in the form of sprays, roll-ons and sticks were investigated using an in vitro-test system (E-Screen assay) for the determination of estrogenic activity based on the human breast cancer cell line MCF-7. Seven out of ten spray deodorant samples showed a quantifiable estrogenic activity. In the case of the sticks and roll-ons it was only one out of six and one out of nine, respectively. The 17 beta-estradiol equivalent concentrations (EEQs) of the samples ranged from 0.1 ng g(-1) to 9 ng g(-1) deodorant. Spray deodorant samples showed the highest activities in the E-Screen assay compared to the stick and roll-on deodorants. In order to identify substances possibly contributing to the observed biological activity the samples were additionally analyzed by GC/MS. The obtained results of this non-target screening led to the selection of 62 single substances present in the deodorants which for their part were analyzed by E-Screen assay. Eight of these single substances, all of them fragrances, showed estrogenic effects with estradiol equivalence factors (EEFs) similar to parabens, a group of 4-hydroxybenzoic acid esters commonly used as preservatives in personal care products, which are known to have a slight estrogenic effect. Thus, these fragrances are obviously responsible to a substantial degree for the observed estrogenic activity of the deodorants. (C) 2014 Elsevier Ltd. All rights reserved.

Discharge of substances like pesticides, pharmaceuticals, flame retardants, and chelating agents in surface waters has increased over the last decades due to the rising numbers of chemicals used by humans and because many WWTPs do not eliminate these substances entirely. The study, results of which are presented here, focused on associations of (1) concentrations of micropollutants in wastewater treatment plant (WWTP) effluents, surface waters, sediments, and tissues of fishes; (2) results of laboratory biotests indicating potentials for effects in these samples and (3) effects either in feral chub (Leuciscus cephalus) from two German rivers (Schussen, Argen) or in brown trout (Salmo trutta f. fario) and rainbow trout (Oncorhynchus mykiss) exposed in bypass systems to streamwater of these rivers or in cages directly in the rivers. The Schussen and Argen Rivers flow into Lake Constance. The Schussen River is polluted by a great number of chemicals, while the Argen River is less influenced by micropollutants. Pesticides, chelating agents, flame retardants, pharmaceuticals, heavy metals, polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs) were detected in effluents of a WWTP discharging to the Schussen as well as in surface water, and/or fishes from downstream of the WWTP. Results obtained by biotests conducted in the laboratory (genotoxicity, dioxin-like toxicity, and embryotoxicity) were linked to effects in feral fish collected in the vicinity of the WWTP or in fishes exposed in cages or at the bypass systems downstream of the WWTP. Dioxin-like effect potentials detected by reporter gene assays were associated with activation of CYP1A1 enzymes in fishes which are inducible by dioxin-like chemicals. Abundances of several PCBs in tissues of fishes from cages and bypass systems were not associated with these effects but other factors can influence EROD activity. Genotoxic potentials obtained by in vitro tests were associated with the presence of micronuclei in erythrocytes of chub from the river. Chemicals potentially responsible for effects on DNA were identified. Embryotoxic effects on zebrafish (Danio rerio), investigated in the laboratory, were associated with embryotoxic effects in trout exposed in streamwater bypass systems at the two rivers. In general, responses at all levels of organization were more pronounced in samples from the Schussen than in those from the Argen. These results are consistent with the magnitudes of chemical pollution in these two streams. Plausibility chains to establish causality between exposures and effects and to predict effects in biota in the river from studies in the laboratory are discussed.