Co-encapsulation of Daphnia magna and microalgae in silica matrices, a stepping stone toward a portable microcosm

We report on the first silica encapsulation of a metazoan (Daphnia magna), with a high initial viability (96% of the population remained active 48 h after encapsulation). Moreover, the co-encapsulation of this crustacean and microalgae (Pseudokirchneriella subcapitata) was achieved, creating inside a silica monolith, the smallest microcosm developed to present. This artificial ecosystem in a greatly diminished scale isolated inside a silica nanoporous matrix could have applications in environmental monitoring, allowing ecotoxicity studies to be carried out in portable devices for on-line and in situ pollution level assessment.Fil: Perullini, Ana Mercedes. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Orias, Frédéric. Université Claude Bernard Lyon 1; FranciaFil: Durrieu, Claude. Université Claude Bernard Lyon 1; FranciaFil: Jobbagy, Matias. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Aldabe, Sara Alfonsina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentin

Contribution à l'évaluation des risques écotoxicologiques des effluents hospitaliers : bioconcentration, bioaccumulation et bioamplification des résidus pharmaceutiques

Hospitals generates effluents rich in pharmaceuticals compounds (PC), notably because of careand diagnostics activities. Some of these PCs are ubiquitous in aquatic ecosystems owing to itspersistent properties and/or because of continuous releasing in environment. The diversity of thesePCs is so strong that it is necessary to prioritize them, considering risks that PCs represents forthe Environment, in order to manage and study these compounds. One of these risks is the transferof bioaccumulatives PCs (i.e. PCs with high Kow and low biodegradability) along trophic webs,via bioconcentration, bioaccumulation and biomagnification processes. The main objective of thisthesis is to characterize bioconcentration and bioaccumulation of molecules identified as priorityin previous studies. The model compound choose in our work is the tamoxifen, a molecule usedin the treatment of breast cancer and already found in Environment. Organisms studied, typicalfrom three trophic levels of the model trophic chain, are Pseudokirchneriella subcapitata, Daphniamagna and Danio rerio. In order to measure content of tamoxifen in organisms, we developed aninnovative analytic method based on the use of stable isotopes labelled tamoxifen : 15N tamoxifen.We succeeded to measure bioconcentration factors (BCF) from 12800 in D. magna to 85600 in liverof D. rerio including BCF of 21500 in P. subcapitata. In this latter, we also assessed the contributionof dietary route to the total contamination of D. magna by tamoxifen. We observed that the morethe medium concentration was weak, the more the dietary route contribute to the contamination.These works shows numerous perspectives that we can gather inside two axes : ecotoxicity knowledgeof PCs an isotopic ecotoxicology.Les hôpitaux génèrent des effluents riches en résidus pharmaceutiques (RP), fonctions de leurs activités de soins et de diagnostic. Certains de ces RP sont aujourd’hui retrouvés de manière ubiquitaire dans les écosystèmes aquatiques, en raison de leurs propriétés persistantes et/ou de leur émission continue. La variété de ces RP est telle qu’il est nécessaire de les hiérarchiser, en fonction des risques qu’ils représentent pour l’Environnement, à des fins d’étude et de gestion. Un de ces risques est le transfert des RP bioaccumulables (i.e. Kow élevé et faible biodégradabilité) dans les chaînes alimentaires, via les processus de bioconcentration, de bioaccumulation et de bioamplification. L’objectif principal de cette thèse est de caractériser expérimentalement la bioconcentration et la bioaccumulation de molécules identifiées comme prioritaires dans des travaux précédents. Le composé modèle que nous avons choisi est le tamoxifen, molécule utilisée contre le cancer du sein et déjà retrouvé dans l’Environnement. Les organismes étudiés, issus des trois niveaux trophiques de la chaine alimentaire modèle, sont Pseudokirchneriella subcapitata, Daphnia magna et Danio rerio. Pour mesurer la teneur de cette molécule dans les organismes, nous avons développé une méthode d’analyse reposant sur l’utilisation d’une molécule marquée par un isotope stable, le 15N tamoxifen.Nous avons mesuré des facteurs de bioconcentration (BCF) allant de 12800 chez D. magna à 85600 dans le foie de D. rerio en passant par 21500 chez P. subcapitata. Chez ces derniers, nous avons également évalué la part du régime alimentaire dans la bioaccumulation du tamoxifen. Nous avons observé que plus la concentration dans le milieu d’exposition est faible, plus le régime alimentaire contribue à la bioaccumulation. Ces travaux de thèse présentent de nombreuses perspectives que l’on peut regrouper autour de deux axes : connaissance de l’écotoxicité des RP et de l’écotoxicologie isotopique

Contribution à l'évaluation des risques écotoxicologiques des effluents hospitaliers : bioconcentration, bioaccumulation et bioamplification des résidus pharmaceutiques

Hospitals generates effluents rich in pharmaceuticals compounds (PC), notably because of careand diagnostics activities. Some of these PCs are ubiquitous in aquatic ecosystems owing to itspersistent properties and/or because of continuous releasing in environment. The diversity of thesePCs is so strong that it is necessary to prioritize them, considering risks that PCs represents forthe Environment, in order to manage and study these compounds. One of these risks is the transferof bioaccumulatives PCs (i.e. PCs with high Kow and low biodegradability) along trophic webs,via bioconcentration, bioaccumulation and biomagnification processes. The main objective of thisthesis is to characterize bioconcentration and bioaccumulation of molecules identified as priorityin previous studies. The model compound choose in our work is the tamoxifen, a molecule usedin the treatment of breast cancer and already found in Environment. Organisms studied, typicalfrom three trophic levels of the model trophic chain, are Pseudokirchneriella subcapitata, Daphniamagna and Danio rerio. In order to measure content of tamoxifen in organisms, we developed aninnovative analytic method based on the use of stable isotopes labelled tamoxifen : 15N tamoxifen.We succeeded to measure bioconcentration factors (BCF) from 12800 in D. magna to 85600 in liverof D. rerio including BCF of 21500 in P. subcapitata. In this latter, we also assessed the contributionof dietary route to the total contamination of D. magna by tamoxifen. We observed that the morethe medium concentration was weak, the more the dietary route contribute to the contamination.These works shows numerous perspectives that we can gather inside two axes : ecotoxicity knowledgeof PCs an isotopic ecotoxicology.Les hôpitaux génèrent des effluents riches en résidus pharmaceutiques (RP), fonctions de leurs activités de soins et de diagnostic. Certains de ces RP sont aujourd’hui retrouvés de manière ubiquitaire dans les écosystèmes aquatiques, en raison de leurs propriétés persistantes et/ou de leur émission continue. La variété de ces RP est telle qu’il est nécessaire de les hiérarchiser, en fonction des risques qu’ils représentent pour l’Environnement, à des fins d’étude et de gestion. Un de ces risques est le transfert des RP bioaccumulables (i.e. Kow élevé et faible biodégradabilité) dans les chaînes alimentaires, via les processus de bioconcentration, de bioaccumulation et de bioamplification. L’objectif principal de cette thèse est de caractériser expérimentalement la bioconcentration et la bioaccumulation de molécules identifiées comme prioritaires dans des travaux précédents. Le composé modèle que nous avons choisi est le tamoxifen, molécule utilisée contre le cancer du sein et déjà retrouvé dans l’Environnement. Les organismes étudiés, issus des trois niveaux trophiques de la chaine alimentaire modèle, sont Pseudokirchneriella subcapitata, Daphnia magna et Danio rerio. Pour mesurer la teneur de cette molécule dans les organismes, nous avons développé une méthode d’analyse reposant sur l’utilisation d’une molécule marquée par un isotope stable, le 15N tamoxifen.Nous avons mesuré des facteurs de bioconcentration (BCF) allant de 12800 chez D. magna à 85600 dans le foie de D. rerio en passant par 21500 chez P. subcapitata. Chez ces derniers, nous avons également évalué la part du régime alimentaire dans la bioaccumulation du tamoxifen. Nous avons observé que plus la concentration dans le milieu d’exposition est faible, plus le régime alimentaire contribue à la bioaccumulation. Ces travaux de thèse présentent de nombreuses perspectives que l’on peut regrouper autour de deux axes : connaissance de l’écotoxicité des RP et de l’écotoxicologie isotopique

Pharmaceuticals in hospital wastewater: Their ecotoxicity and contribution to the environmental hazard of the effluent

International audienceNowadays, pharmaceuticals are found in every compartment of the environment. Hospitals are one of the main sources of these pollutant emissions sent to wastewater treatment plants (WWTP) that are poorly equipped to treat these types of compounds efficiently. In this work, for each pharmaceutical compound found in hospital wastewater (HWW), we have calculated a hazard quotient (HQ) corresponding to the highest concentration measured in HWW divided by its predicted no effect concentration (PNEC). Thus we have assessed the contribution of each compound to the ecotoxicological threat of HWW taken as a whole. Fifteen compounds are identified as particularly hazardous in HWW. In future more attention should be given to their analysis and replacement in hospitals, and to their elimination in WWTPs. This work also highlights the lack of knowledge of the ecotoxicity of certain pharmaceutical compounds found in HWW at high concentrations (mg L1). In order to extend this study, it is now necessary to investigate ecotoxic risks linked to various emission scenarios, focusing in particular on dilution in the aquatic environment and the production of metabolites, especially during transit inside WWTPs

Experimental assessment of the bioconcentration of 15N-tamoxifen in Pseudokirchneriella subcapitata

International audienceNowadays, pharmaceutical compounds (PC) are ubiquitous in aquatic ecosystems. In addition to direct ecotoxicity, the bioconcentration of PC in organisms is a phenomenon which could have an impact on the whole ecosystem. In order to study this phenomenon, we exposed unicellular algae (Pseudokirchneri- ella subcapitata) to 15N-tamoxifen, an anticancer drug labelled with a stable nitrogen isotope used as a tracer. By measuring 15N enrichment over time, we were able to measure the increase of tamoxifen con- tent in algae. This enrichment was measured by an elemental analyser coupled with an isotopic ratio mass spectrometer (EA–IRMS). Algal cells were exposed for 7 d to 3 concentrations of tamoxifen: 1, 10 and 100 lg L1. Our result shows a high bioconcentration in algae from the first minutes of contact. The highest bioconcentration factor measured is around 26500. We also observe that bioconcentration is not linked to the exposure concentration. This study is the first to use stable isotopes in order to monitor PCs in aquatic organisms such as algae. The use of stable isotopes in ecotoxicology offers interesting perspectives in the field of contaminant transfer in organisms and along the trophic web

Respective contributions of diet and medium to the bioaccumulation of pharmaceutical compounds in the first levels of an aquatic trophic web

International audienceNowadays, pharmaceuticals (PCs) are ubiquitous in aquatic ecosystems. It is known that these compounds have ecotoxic effects on aquatic organisms at low concentrations. Moreover, some of them can bioaccumulate inside organisms or trophic webs exposed at environmental concentrations and amplify ecotoxic impacts. PCs can bioaccumulate in two ways: exposure to a medium (e.g., respiration, diffusion, etc.) and/or through the dietary route. Here, we try to assess the respective contributions of these two forms of contamina- tion of the first two levels of an aquatic trophic web. We exposed Daphnia magna for 5 days to 0, 5, and 50 μg/L 15N-tamoxifen and then fed them with control and contami- nated diets. We used an isotopic method to measure the ta- moxifen content inside the daphnids after several minutes’ exposure and every day before and after feeding. We found that tamoxifen is very bioaccumulative inside daphnids (BCF up to 12,000) and that the dietary route has a significant im- pact on contamination by tamoxifen (BAF up to 22,000), es- pecially at low concentrations in medium

Identification and assessment of ecotoxicological hazards attributable to pollutants in urban wet weather discharges

International audienceThe phenomenon of urbanization leads to considerable pressure on urban/suburban aquatic ecosystems. Urban Wet Weather Discharges (UWWDs) during rainfall events are a major source of pollutants leached onto and into urban surfaces and sewers, which in turn affect aquatic ecosystems. The aim of this study is to assess the ecotoxicity of the different compounds identified in UWWDs and identify the hazard represented by each of them. To this end, hazard quotients (HQ) were calculated for each compound detected in UWWDs, based on their Predicted No Effect Concentration (PNEC) values and their maximum concentration (MECmax) found in the dissolved part of UWWDs. For the 207 compounds identified in UWWDs, sufficient data existed for 165 of them to calculate their PNEC. The ecotoxicity of these compounds is greatly variable. Pesticides represent a high proportion of the wide variety of hazardous compounds whose HQ were calculated (a total of 94 HQ), and they are among the most hazardous pollutants (HQ >1000) transported by stormwater. On the contrary, the hazard of Combined Sewer Overflows (CSO) is mainly linked to heavy metals and pharmaceutical compounds. Consequently, the monitoring of these pollutants is a priority in the future. Lastly, it is to bear in mind that the hazard level of certain pollutants could be underestimated, due to their adsorption on particles, leading their low presence in the dissolved phase of UWWDs. So, an in-depth study of these pollutants will be required to clarify their effects on aquatic organisms

Co-encapsulation of Daphnia magna and microalgae in silica matrices, a stepping stone toward a portable microcosm

We report on the first silica encapsulation of a metazoan (Daphnia magna), with a high initial viability (96% of the population remained active 48 h after encapsulation). Moreover, the co-encapsulation of this crustacean and microalgae (Pseudokirchneriella subcapitata) was achieved, creating inside a silica monolith, the smallest microcosm developed to present. This artificial ecosystem in a greatly diminished scale isolated inside a silica nanoporous matrix could have applications in environmental monitoring, allowing ecotoxicity studies to be carried out in portable devices for on-line and in situ pollution level assessment

Mechanistic modelling of daphnid-algae dynamics within a laboratory microcosm

International audienceOur study describes the functioning of a 2-L laboratory microcosm of two species, daphnids (Daphnia magna) and microalgae (Pseudokirchneriella subcapitata), in two abiotic phases (water column and sedi- ment). We modelled the dynamics of both species and their interactions using a mechanistic model based on coupled ordinary differential equations. The main processes occurring in this two-species microcosm were thus formalised, including growth and settling of algae and growth, survival and grazing of daph- nids. We estimated model parameters by Bayesian inference, using simultaneously all data from multiple experiments specifically conducted for this study. Two types of model verifications were performed: (1) internal verification to validate model structure and parameter estimation method using all data simul- taneously; and (2) external verification to validate the ability of the model to be applied under new sediment conditions. For all parameters, we obtained biologically realistic values and reasonable uncer- tainties. The first verification step allowed us to confirm the modelled processes and the benefits of our parameter estimation method. The second one confirmed the ability of the model to describe microcosm functioning under different abiotic conditions. This innovative combination of mechanistic modelling and model-guided experiments revealed successful to understand the algae-daphnid microcosm func- tioning. This approach appears promising and can be applied to various issues in the ecological and ecotoxicological fields

Évaluation des risques écotoxicologiques liés aux effluents hospitaliers et recommandations de gestion

International audienc