Département Chimie de l’environnement

Sur la piste des polluants

Nos recherches portent sur la présence, la distribution et la persistance de polluants organiques dans l'environnement aquatique. L'accent est mis sur les flux de matières issus des zones urbaines et agricoles. Les principaux outils sont l'analyse des traces, les études en laboratoire et sur le terrain et la modélisation.

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Actuel publications

Pesticide risks in small streams - how to get as close as possible to the stress imposed on aquatic organisms

The risks associated with pesticides in small streams remain poorly characterized. The challenges reside in understanding the complexities of (1) the highly dynamic concentration profiles of (2) several hundred active substances with (3) differing seasonality. The present study addressed these three challenges simultaneously. Five small streams in catchments under intensive agricultural land use were sampled using half-day composite samples from March to August 2015. Of 213 active substances quantified using liquid chromatography–high resolution mass spectrometry, a total of 128 was detected at least at one of the sites. Ecotoxicological acute and/or chronic quality criteria were exceeded for a total of 32 different active substances. The evaluation of risks over time revealed the necessity to evaluate the sequences of different active substances that are imposed on aquatic organisms. In contrast, a substance-specific perspective provides only a very limited assessment. Scenarios for reduction of either temporal resolution, number of substances or seasonal coverage were defined. It could be shown that risks can be underestimated by more than a factor of 10 in vulnerable catchments and that an increased temporal resolution is essential to cover acute risks but that a focused selection of substances is a possibility to reduce expenditures.
Spycher, S.; Mangold, S.; Doppler, T.; Junghans, M.; Wittmer, I.; Stamm, C.; Singer, H. (2018) Pesticide risks in small streams - how to get as close as possible to the stress imposed on aquatic organisms, Environmental Science and Technology, 52(8), 4526-4535, doi:10.1021/acs.est.8b00077, Institutional Repository

Ion trapping of amines in protozoa: a novel removal mechanism for micropollutants in activated sludge

To optimize removal of organic micropollutants from the water cycle, understanding the processes during activated sludge treatment is essential. In this study, we hypothesize that aliphatic amines, which are highly abundant among organic micropollutants, are partly removed from the water phase in activated sludge through ion trapping in protozoa. In ion trapping, which has been extensively investigated in medical research, the neutral species of amine-containing compounds diffuse through the cell membrane and further into acidic vesicles present in eukaryotic cells such as protozoa. There they become trapped because diffusion of the positively charged species formed in the acidic vesicles is strongly hindered. We tested our hypothesis with two experiments. First, we studied the distribution of the fluorescent amine acridine orange in activated sludge by confocal fluorescence imaging. We observed intense fluorescence in distinct compartments of the protozoa, but not in the bacterial biomass. Second, we investigated the distribution of 12 amine-containing and eight control micropollutants in both regular activated sludge and sludge where the protozoa had been inactivated. In contrast to most control compounds, the amine-containing micropollutants displayed a distinctly different behavior in the noninhibited sludge compared to the inhibited one: (i) more removal from the liquid phase; (ii) deviation from first-order kinetics for the removal from the liquid phase; and (iii) higher amounts in the solid phase. These results provide strong evidence that ion trapping in protozoa occurs and that it is an important removal mechanism for amine-containing micropollutants in batch experiments with activated sludge that has so far gone unnoticed. We expect that our findings will trigger further investigations on the importance of this process in full-scale wastewater treatment systems, including its relevance for accumulation of ammonium.
Gulde, R.; Anliker, S.; Kohler, H.-P. E.; Fenner, K. (2018) Ion trapping of amines in protozoa: a novel removal mechanism for micropollutants in activated sludge, Environmental Science and Technology, 52(1), 52-60, doi:10.1021/acs.est.7b03556, Institutional Repository

Misfit between physical affectedness and regulatory embeddedness: thecase of drinking water supply along the Rhine River

One open question in environmental sciences is whether effective management of natural resources depends on the fit between the bio-physical and the governance system. To address this question, we investigate water quality in transboundary rivers and ask to what extent a fit between the area covered by the physical extent of pollution and the area in which this pollution is addressed through management and policy regulation can be observed. We adopt a spatial approach and argue that the visualization of social-ecological overlap and misfit supports science and practice when taking decisions about how best to explain or address ineffectiveness and cause-effect mismatches in transboundary river management.
We focus on drinking water supply in the international river basin of the Rhine focusing on micropollutants. These persistent trace compounds have potential toxic effects on humans and ecosystems, which makes them a relevant type of pollution that needs to be taken into consideration. Based on a combination of mass flow and social network analysis, we can conclude that the Rhine River is characterized by large social-ecological overlap, but that some parts of the catchment area still lack integration.
Ingold, K.; Moser, A.; Metz, F.; Herzog, L.; Bader, H.-P.; Scheidegger, R.; Stamm, C. (2018) Misfit between physical affectedness and regulatory embeddedness: thecase of drinking water supply along the Rhine River, Global Environmental Change, 48, 136-150, doi:10.1016/j.gloenvcha.2017.11.006, Institutional Repository

Non-target screening to trace ozonation transformation products in a wastewater treatment train including different post-treatments

Ozonation and subsequent post-treatments are increasingly implemented in wastewater treatment plants (WWTPs) for enhanced micropollutant abatement. While this technology is effective, micropollutant oxidation leads to the formation of ozonation transformation products (OTPs). Target and suspect screening provide information about known parent compounds and known OTPs, but for a more comprehensive picture, non-target screening is needed. Here, sampling was conducted at a full-scale WWTP to investigate OTP formation at four ozone doses (2, 3, 4, and 5 mg/L, ranging from 0.3 to 1.0 gO3/gDOC) and subsequent changes during five post-treatment steps (i.e., sand filter, fixed bed bioreactor, moving bed bioreactor, and two granular activated carbon (GAC) filters, relatively fresh and pre-loaded). Samples were measured with online solid-phase extraction coupled to liquid chromatography high-resolution tandem mass spectrometry (LC-HRMS/MS) using electrospray ionization (ESI) in positive and negative mode. Existing non-target screening workflows were adapted to (1) examine the formation of potential OTPs at four ozone doses and (2) compare the removal of OTPs among five post-treatments. In (1), data processing included principal component analysis (PCA) and chemical knowledge on 31 possible oxidation reactions to prioritize non-target features likely to be OTPs. Between 394 and 1328 unique potential OTPs were detected in positive ESI for the four ozone doses tested; between 12 and 324 unique potential OTPs were detected in negative ESI. At a specific ozone dose of 0.5 gO3/gDOC, 27 parent compounds were identified and were related to 69 non-target features selected as potential OTPs. Two OTPs were confirmed with reference standards (venlafaxine N-oxide and chlorothiazide); 34 other potential OTPs were in agreement with literature data and/or reaction mechanisms. In (2), hierarchical cluster analysis (HCA) was applied on profiles detected in positive ESI mode across the WWTP and revealed 11 relevant trends. OTP removal was compared among the five post-treatments and 54–83% of the non-target features that appeared after ozonation were removed, with the two GAC filters performing the best. Overall, these data analysis strategies for non-target screening provide a useful tool to understand the behavior of unknown features during ozonation and post-treatment and to prioritize certain non-targets for further identification.
Schollée, J. E.; Bourgin, M.; von Gunten, U.; McArdell, C. S.; Hollender, J. (2018) Non-target screening to trace ozonation transformation products in a wastewater treatment train including different post-treatments, Water Research, doi:10.1016/j.watres.2018.05.045, Institutional Repository

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L’Eawag à la une de « Environmental Science & Technology »

Grafik: Eawag, Livia Enderli

18 Mai 2018, Pour la deuxième fois en peu de temps, la recherche de l’Eawag a fait la une de la revue « Environmental Science & Technology ». En avril, le travail du chercheur Urs von Gunten et de son équipe de l’Eawag, portant sur la compréhension de l’ozonation des phénols, a été sélectionné comme article de choix de l’éditeur par l’American Chemical Society ACS et a figuré en couverture du journal spécialisé. [plus d'informations]

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Projets de recherche

Demonstration of promising technologies to address emerging pollutants in water and wastewater.

DEMEAU
Les mesures complètes des micropolluants organiques dans les eaux sont complexes. Le projet NAWA Spez fournit des données et des analyses sur l'état de la pollution.

NAWA SPEZ
Predicting environment-specific biotransformation of chemical contaminants

PROduCTS - ERC
Die Überwachung von Oberflächengewässern hinsichtlich polarer und semipolarer organischer Mikroschadstoffe ist stark an die chemische Analytik gekoppelt...

Computergestützte Detektion von Mikroschadstoffen in Oberflächengewässern mittels hochauflösender Massenspektrometrie

 Autres projets de recherche