Project

bioaccumulation; invertebrates; biotransformation; organic trace analysis; organic xenobiotics; algal communities; high resolution mass spectrometry; toxicokinetic modelling

Lead
Bioakkumulation und Biotransformation von organischen Fremdstoffen in WasserorganismenWissen über die Anreicherung (Bioakkumulation) und Umsetzung (Biotransformation) von organischen Verbindungen in Organismen der aquatischen Nahrungskette ist wichtig, um die Schadstoffbelastung der Organismen in der Umwelt mit den Wirkungen zu verknüpfen. Mit Hilfe dieses Wissens können Qualitätsstandards für das Oberflächenwasser in der Schweiz und im Rahmen der europäischen Wasserrahmenrichtlinie (WFD) besser wissenschaftlich abgeleitet werden sowie das Potential für biologische Anreicherung im Rahmen der Registrierung von Chemikalien (REACH) bestimmt werden.
Lay summary
Das übergeordnete Ziel des Projektes ist es, die Bioakkumulation und Biotransformation von polaren organischen Mikroschadstoffen wie ausgewählte Arzneistoffe und Pflanzenschutzmittel in aquatischen Organismen zu charakterisieren. Um verschiedene Stufen der Nahrungskette abzudecken, werden wir Laborversuche mit Wasserflohkrebsen (Gammariden) und Algen durchführen. Hierbei wollen wir auch Stoffmischungen einsetzen, da die Stoffe sich gegenseitig beeinflussen können, was zu einer veränderten toxischen Wirkung führen kann. Die Stoffe und ihre Biotransformationsprodukte werden sensitiv mit der Flüssigchromatographie mit hochauflösender Massenspektrometrie im Wasser und in den Organismen identifiziert, quantifiziert sowie anschliessend die zeitliche Dynamik modelliert. Für die Algen wollen wir ferner untersuchen, inwiefern die Laborergebnisse auf Algengemeinschaften im Feld übertragen werden können und wie stark Algen zur Entfernung von organischen Stoffe in den Gewässern beitragen. Dazu werden auch die Algengemeinschaft in Seen mittels der Durchflusszytometrie von der Gruppe von Franzesco Pomati (Eawag) charakterisiert und mit den Schadstoffprofilen im See verglichen. Um zu untersuchen, ob Wasserflohkrebse sich für ein Biomonitoring eignen und in der Zukunft Fische ersetzen können, wollen wir bestimmen, welche Mikroschadstoffe in den Krebstierchen nachweisbar sind und ob dies mit der Oberflächenwasserqualität korreliert. So werden wir die Belastung der Gammariden ober- und unterhalb von Kläranlagen bestimmen und mit der chemischen und ökologischen Qualität der Gewässer vergleichen.

Direct link to Lay Summary

Last update: 29.03.2016

Active participation

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Knowledge on the importance of bioaccumulation and biotransformation of anthropogenic organic xenobiotics in aquatic organisms is essential to mechanistically link environmental exposure with ecotoxicological and ecological effects. It is also important for derivation of environmental quality standards in the context of the Water Framework Directive as well as for the evaluation of the bioaccumulation potential for registration of new chemicals within REACH. In the running project we have characterized oxidative biotransformation processes of several pesticides and pharmaceuticals in daphnids and gammarids as well as in eukaryotic and prokaryotic algal strains. We proposed transformation pathways based on structure elucidation of biotransformation products (BTP) with liquid chromatography linked to high resolution tandem mass spectrometry, enzymatic inhibition of P450 oxidative enzymes, and metabolic logic. Modelling first-order kinetics of exposure and depuration experiments yielded kinetic rate constants for selected compounds and showed that biotransformation is an important detoxifying process for several compounds (e.g. strobilurin fungicides, tramadol) but other compounds (e.g. several azoles) remain rather persistent.In the proposed continuation project we aim to build on our results and increase the complexity of the systems to address the co-occurrence of chemicals in the environment and the bioaccumulation and biotrans-formation by algal communities instead of single species. Further, we want to explore biomonitoring of gammarids in human impacted environments and correlate biota concentrations with chemical profiles from the environment to link ecotoxicological and ecological outcomes with chemical contamination. We will use the developed analytical and biological methods and focus on three main questions: 1.How do environmental mixtures affect the bioaccumulation and biotransformation of xenobiotics in gammarids and result in changed toxicity? 2.How and to what extent does the bioaccumulation and biotransformation in algal communities contribute to the fate of xenobiotics in the environment? 3.Can the internal xenobiotic concentrations in gammarids in the environment be linked to the surface water concentrations and thus are gammarids a suitable alternative to fish biomonitoring? We plan to use a set of organic compounds (strobilurin fungicides, azole fungicides, selected pharmaceuticals) that comprise a variety of functional groups with different physicochemical properties and showed various biotransformation half-lives in the running project. For research question 1, concentration addition and synergy will be explored in gammarids using binary and ternary contaminant mixtures. P450 inhibition and induction, which is generally accepted as the most important reason for synergy, will be investigated using highly biotransforming strobilurin fungicides as model compounds and azoles and triazines as inhibitors and inducers, respectively. The change in P450 activity, studied also in an in vivo assay, will be included into the toxicokinetic modelling via Michaelis-Menten kinetics and the model will be used to predict the relevance of such synergetic processes for environmental concentrations. Dose-response curves with internal concentrations will be used to mechanistically link the toxicokinetics with toxicodynamic processes.Research question 2 will be addressed by laboratory experiments with various strains of Microcystis, Chlamydomonas, diatom strains and their biotransformation potential will be compared with that of natural algal communities from lakes with different trophic state. The taxonomic and the functional diversity of the sampled communities will be related to the observed biotransformation potential indicating the influence of the community biodiversity on the degradation pattern. Comparison with known transformation half-lives for abiotic and microbial processes will reveal the importance of the algal communities for the fate of chemicals in the natural environment. To verify the environmental relevance, we aim to determine concentration profiles of selected compounds with high and low biotransformation potential in Lake Greifen during summer stratification. The lake algal community will simultaneously be characterized by flow-cytometry by the group of F. Pomati at Eawag. Internal concentrations in the algal biomass will be determined using the developed nano SPE-LC-MS/MS method that will be further optimized for the trace concentrations.To test whether gammarids are suitable organisms as an alternative to fish in biomonitoring (research question 3), we will study which part of the chemical variety of micropollutants can be detected analytically in gammarids and whether this reflects the surface water quality. Therefore, a sensitive analytical method for a broad screening of polar contaminants in gammarids for environmentally relevant concentrations will be developed and target, suspect and non-target screening in gammarids both up- and downstream of three wastewater treatment plants will be conducted. Using multivariate statistics, the peak pattern found in the surface water and the gammarids up- and downstream of wastewater treatment plants will be compared and relevant peaks will be tentatively identified using mass-spectrometric information. The results will be compared with the ecological quality of the streams such as macrobenthos diversity as well as ecotoxicological data determined in other research projects (EcoImpact, Solutions).