63 research outputs found
Effect of Sequential Isoproturon Pulse Exposure on Scenedesmus vacuolatus
Aquatic organisms are typically exposed to fluctuating concentrations of herbicides in streams. To assess the effects on algae of repeated peak exposure to the herbicide isoproturon, we subjected the alga Scenedesmus vacuolatus to two sequential pulse exposure scenarios. Effects on growth and on the inhibition of the effective quantum yield of photosystem II (PSII) were measured. In the first scenario, algae were exposed to short, 5-h pulses at high isoproturon concentrations (400 and 1000 ÎŒg/l), each followed by a recovery period of 18 h, while the second scenario consisted of 22.5-h pulses at lower concentrations (60 and 120 ÎŒg/l), alternating with short recovery periods (1.5 h). In addition, any changes in the sensitivity of the algae to isoproturon following sequential pulses were examined by determining the growth rate-EC50 prior to and following exposure. In both exposure scenarios, we found that algal growth and its effective quantum yield were systematically inhibited during the exposures and that these effects were reversible. Sequential pulses to isoproturon could be considered a sequence of independent events. Nevertheless, a consequence of inhibited growth during the repeated exposures is the cumulative decrease in biomass production. Furthermore, in the second scenario, when the sequence of long pulses began to approach a scenario of continuous exposure, a slight increase in the tolerance of the algae to isoproturon was observed. These findings indicated that sequential pulses do affect algae during each pulse exposure, even if algae recover between the exposures. These observations could support an improved risk assessment of fluctuating exposures to reversibly acting herbicide
Multicriteria methods for assessing pharmaceuticals hazard for the environment
Among emerging pollutants found in surface and ground waters, pharmaceuticals are currently receiving a particular interest. There are several physico/chemical parameters that could describe the fate of pharmaceuticals in the environment, so as their toxicity for ecosystems and human health. The idea is to create an integrated parameter that would relate of the relative influence of these physico/chemical characteristics. Potential impact of pharmaceuticals on the environment could be then ranked using this parameter. Different methods will be tested for ranking (weighted average, mathematical distance functions from the no effect point, ELECTRE, etc). The weights were evaluated in order not to support only a scientific point of view, but also economical and social considerations. For this concern, cooperation with scientists from various fields so as human health managers was carried out. The different methods will be finally compared together so as with previous ranking published in literature. The goal here is not to impose a relative importance of the parameters we integrate, but to introduce the concept of the relative influence for environmental parameters when we deal with water quality problems that could affect ecological systems and human health
Risk of herbicide mixtures as a key parameter to explain phytoplankton fluctuation in a great lake: the case of Lake Geneva, Switzerland
Mixture risk assessment predictions have rarely been confronted with biological changes observed in the environment. In this study, long-term monitoring of a European great lake, Lake Geneva, provides the opportunity to assess to what extent the predicted toxicity of herbicide mixtures explains the changes in the composition of the phytoplankton community next to other classical limnology parameters such as nutrients. To reach this goal, the gradient of the mixture toxicity of 14 herbicides regularly detected in the lake was calculated using concentration addition and response addition models. A temporal gradient of toxicity was observed which decreased from 2004 to 2009. Redundancy analysis and partial redundancy analysis showed that this gradient explains a significant portion of the variation in phytoplankton community composition with and without having removed the effect of all other co-variables. Moreover, species that are significantly influenced, positively or negatively, by the decrease of toxicity in the lake over time are highlighted. It can be concluded that the herbicide mixture toxicity is one of the key parameters to explain phytoplankton changes in Lake Genev
Toxicity of Tamoxifen on Daphnia pulex
Daphnia pulex is a water flea considered an environmental indicator species. In this experiment we exposed Daphnia to Tamoxifen in low or high concentrations, dissolved in dimethyl sulfoxide with water, and we measured the amount of proteins at day 2 and 7. With the R package maSigPro we selected proteins changing significantly over time among the four experimental groups and we developed a cluster analysis for the behavior of profiles over time, to understand which and how these specific proteins change according to the treatment received. The information obtained from this study represents an important first step towards characterizing patterns specific to environmental contaminants
Development of a new ecotoxicological assay using the testate amoeba <i>Euglypha rotunda</i> (Rhizaria; Euglyphida) and assessment of the impact of the herbicide <i>S</i>-metolachlor
An ever-increasing diversity of potentially toxic chemical compounds are being developed and released into the environment as a result of human activities (e.g. agriculture, drugs, and cosmetics). Among these, pesticides have been shown to affect non-targeted wildlife since the 1960s. A range of ecotoxicological tests are used to assess the toxicity of pesticides on various model organisms. However most model organisms are metazoans, while the majority of Eukaryotes are unicellular microorganisms known as protists. Protists are ubiquitous organisms of key functional roles in all ecosystems but are so far little studied with respect to pesticide impact. To fill this gap, we developed a new ecotoxicological test based on Euglypha rotunda, a common soil amoeba, grown in culture flask with Escherichia coli as sole food source. We tested this assay with the herbicide S-metolachlor, which is known to affect cell division in seedling shoots and roots of weeds. Reproducible growth conditions were obtained for E. rotunda. The growth of E. coli was not affected by the herbicide. The growth of E. rotunda was affected by the herbicide in a non-linear way, growth being significantly reduced at ca. 15 ÎŒg/L, but not at 150 ÎŒg/ L. Our results show the potential for using soil protists in ecotoxicology and adds to the growing body of evidence for non-linear impacts of pesticides on non-target organisms. With the acquisition of additional data, the protocol should be suitable for standard ecotoxicological tests
Biocides in paints in urban areas: Modelling an underestimated source of environmental contamination
Biocide contamination of receiving waters is generally linked with agriculture. However, recent studies have shown that urban contributions should be also considered. One of the suspected biocide sources in the urban environment is building paint. Biocides like diuron, irgarol, terbutryn, carbendazim, etc., are conventionally used in paint to control fungi, algae, bacteria and other microorganisms that can colonize building façades. The problem of biocides in urban areas is closely linked to meteorological conditions and in particular to rain events. As a consequence, it is important to understand how rainwater collects and transports biocides from façades and how these biocides are transported in sewer systems to receiving waters. In this study, we present a conceptual model describing façade leaching and couple it with a Wind Driven Rain model and a classical hydrological model to compute the contribution of a city to the biocide load from building paint. For the entire city of Lausanne (Switzerland, 200â000 inhabitants), a global production of 2200 kg/year of terbutryn leached by rain was estimated considering local building characteristics and meteorological information. The leaching model fitted well the peak in concentration measured at the bottom of the wall at the initial stage of the rain event. However, concentrations measured in an urban river in the watershed leads to the conclusion that most of this leachate does not reach directly receiving waters, but is infiltrated into soil or reaches the sewers after some delays in drainage pipes. Release of biocides from façade leaching in the environment is systematic during rain event. It is of greater importance to estimate the dynamic of biocides during rain events and to compare these values with dedicated time varying environmental quality criteria
Traitement des micropolluants dans les eaux usées - Rapport final sur les essais pilotes à la STEP de Vidy (Lausanne)
De nombreux micropolluants organiques prĂ©sents dans les eaux usĂ©es sont mal Ă©liminĂ©s dans les stations dâĂ©puration (STEP) conventionnelles. Pour rĂ©duire lâapport de ces substances dans les eaux de surface, des traitements avancĂ©s sont nĂ©cessaires. Deux traitements biologiques et deux traitements avancĂ©s ont Ă©tĂ© testĂ©s Ă grande Ă©chelle Ă la STEP de Vidy (Lausanne) (220'000 Ă©quivalents-habitants) pendant plus dâune annĂ©e. Ces essais sâinscrivent dans le cadre du projet « StratĂ©gie Micropoll » de lâOffice fĂ©dĂ©ral de lâenvironnement (OFEV). Un nouveau traitement biologique Ă lit fluidisĂ© avec nitrification totale (capacitĂ© de 80 l/s) a Ă©tĂ© construit en parallĂšle au procĂ©dĂ© Ă boues activĂ©es forte charge (sans nitrification) actuellement en place (capacitĂ© de 1â200 l/s). Ceci a permis de comparer lâefficacitĂ© dâĂ©limination des micropolluants dans ces deux types de biologie et dâĂ©tudier leur influence sur les traitements avancĂ©s qui suivent. Les deux traitements avancĂ©s testĂ©s sont lâozonation suivie dâune filtration sur sable (ozonation-FS) (capacitĂ© de lâinstallation de 100 l/s) et le traitement au charbon actif en poudre suivi dâune filtration membranaire (ultrafiltration) (CAP-UF) (capacitĂ© de 10 l/s). Conçue sur la base de prĂ©cĂ©dentes Ă©tudes du projet « StratĂ©gie Micropoll », lâinstallation dâozonation a Ă©tĂ© maĂźtrisĂ©e en quelques mois, et seuls quelques paramĂštres ont dĂ» ĂȘtre amĂ©liorĂ©s. En revanche, beaucoup dâĂ©lĂ©ments techniques ont dĂ» ĂȘtre corrigĂ©s sur lâinstallation CAP-UF (procĂ©dĂ© nouveau pour le traitement des eaux usĂ©es). La phase de sĂ©paration du CAP par ultrafiltration nâest pas encore maĂźtrisĂ©e et nĂ©cessite des optimisations, notamment pour rĂ©duire le colmatage (rĂ©versible) des membranes, responsable dâune capacitĂ© hydraulique infĂ©rieure Ă la moitiĂ© de la capacitĂ© espĂ©rĂ©e. La sĂ©paration du CAP par un filtre Ă sable est une alternative possible. Sur une sĂ©lection de plus de 50 micropolluants organiques (produits pharmaceutiques, pesticides, substances Ă effet hormonal), le traitement biologique Ă boues activĂ©es forte charge a permis dâatteindre un abattement moyen de 23%. Avec un traitement biologique permettant une nitrification, le taux dâĂ©limination a augmentĂ© Ă 44% en moyenne, confirmant les rĂ©sultats dâautres Ă©tudes. Le traitement ozonation-FS a permis dâĂ©liminer Ă plus de 80% la plupart des substances analysĂ©es, avec un dosage dâozone moyen dâenviron 5.5 mgO3/l (Ă©quivalent Ă environ 0.9 gO3/gCOD), pour des coĂ»ts dâexploitation dâenviron 6 ct./m3 traitĂ©. Une dĂ©sinfection partielle de lâeffluent a Ă©galement pu ĂȘtre atteinte, conduisant ainsi au respect des normes suisses et europĂ©ennes de qualitĂ© pour les eaux de baignade. Le traitement CAP-UF a permis dâĂ©liminer Ă plus de 80% la plupart des micropolluants, avec un dosage de CAP compris entre 10 et 20 mg/l. La sĂ©paration du CAP par ultrafiltration permet une dĂ©sinfection totale de lâeffluent. A cause des faibles dĂ©bits de lâinstallation CAP-UF (colmatage des membranes), les coĂ»ts dâexploitation Ă©taient proches de 50 ct./m3 traitĂ©. Lâalternative avec la sĂ©paration du CAP sur un filtre Ă sable (testĂ©e dans des essais complĂ©mentaires) coĂ»terait entre 6 et 9 ct./m3. Sur la majoritĂ© des 25 tests Ă©cotoxicologiques effectuĂ©s, une nette rĂ©duction de la toxicitĂ© a Ă©tĂ© observĂ©e en sortie des deux traitements avancĂ©s. Aucune toxicitĂ© liĂ©e aux sous-produits de rĂ©action potentiellement formĂ©s durant lâozonation nâa Ă©tĂ© observĂ©e. Ces deux procĂ©dĂ©s (ozonation et adsorption sur CAP) sont efficaces pour rĂ©duire lâapport de micropolluants dans les eaux de surface. Les technologies ozonation-FS et CAP-FS sont rĂ©alistes autant du point de vue de leur implantation dans les STEP que de leur exploitation, pour des coĂ»ts dâinvestissement et dâexploitation relativement similaires (environ 20 centimes par mĂštre cube dâeau traitĂ©e lors des essais). Chaque technique ayant ses avantages, le choix du procĂ©dĂ© doit ĂȘtre fait au cas par cas en fonction des contraintes locales (espace Ă disposition, type de traitement existant, sĂ©curitĂ©, qualifications du personnel, coĂ»ts des rĂ©actifs, lieu et type de traitement des boues, etc.), de la qualitĂ© de lâeau entrante et de la qualitĂ© voulue en sortie
Elimination of micropollutants in wastewater treatment plants : Ozonation or activated carbon? Conclusions of a one-year pilot project
Many organic micropollutants present in wastewater, such as pharmaceuticals and pesticides, are poorly removed in conventional wastewater treatment plants (WWTP). To reduce the release of these substances into the aquatic environment, advanced treatments are necessary and may be soon mandatory in Switzerland. Two advanced treatments were tested in pilot systems over more than one year at the municipal WWTP of Lausanne, Switzerland. The first pilot involves the ozonation of the effluent to oxidize organic substances. It is followed by a sand filtration (SF) to remove the readily biodegradable reaction products. The second pilot consists of a powdered activated carbon (PAC) addition into the effluent to sorb micropollutants. It is followed either by a membrane filtration (ultrafiltration) or a sand filtration to separate the PAC from the treated water. A selection of 58 potentially problematic substances (pharmaceuticals, pesticides, endocrine disruptors) were regularly measured at different stages of treatment by ultra performance liquid chromatography coupled to a tandem mass spectrometer, and a large battery of ecotoxicological tests (16 in vitro and 9 in vivo assays with different organisms) were performed to evaluate the toxicity of the effluents. The results showed that most compounds were removed over 80% with an average ozone dose of about 5.5 mgO3/l or a PAC dose between 10 and 20 mg/l. Only some single compounds, such as X-ray contrast media, were only partially eliminated in both cases. A clear reduction in toxicity was also observed after the two treatments in most of the cases. These two processes (ozonation and PAC addition) are therefore effective to reduce the release of micropollutants into surface waters. Ozonation-SF and PAC-SF proved to be feasible in terms of implementation and operation at large-scale in WWTP, for relatively similar investment and operation costs (about 0.1 to 0.15 ⏠per m3 treated based on local costs). Each technique has its advantages and disadvantages. Therefore the method selection should be made case by case for each WWTP depending on the local constraints (e.g. space, security, energy costs, existing treatment processes, sludge disposal process, need for disinfection, etc.), the quality and the quantity of incoming water and the desired output water quality
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