International audience | Research has been conducted within the framework of the French Initiative for Coral Reefs (IFRECOR) to assess pesticide pollution levels in the coral reef trophic webs in French Polynesia. Unexpected widespread contamination by herbicides was found in algae, fishes and macro-invertebrates located at various levels of the reef trophic web. Concentrations in organisms investigated were for the majority below the lowest observable effect level and do not pose a dietary risk to native population who subsist on these fish. However, the widespread contamination may affect the reef ecosystem in the future as coral symbiotic algae, Symbidinium sp. (Dinophyta) are particularly sensitive to photosystem II herbicides, particularly the substituted urea and triazine derivatives.

International audience | : This paper compares the removal performances of two complete wastewater treatment plants (WWTPs) for all priority substances listed in the Water Framework Directive and additional compounds of interest including flame retardants, surfactants, pesticides, and personal care products (PCPs) (n = 104). First, primary treatments such as physicochemical lamellar settling (PCLS) and primary settling (PS) are compared. Similarly, biofiltration (BF) and conventional activated sludge (CAS) are then examined. Finally, the removal efficiency per unit of nitrogen removed of both WWTPs for micropollutants is discussed, as nitrogenous pollution treatment results in a special design of processes and operational conditions. For primary treatments, hydrophobic pollutants (log K ow > 4) are well removed (>70 %) for both systems despite high variations of removal. PCLS allows an obvious gain of about 20 % regarding pollutant removals, as a result of better suspended solids elimination and possible coagulant impact on soluble compounds. For biological treatments, variations of removal are much weaker, and the majority of pollutants are comparably removed within both systems. Hydrophobic and volatile compounds are well (>60 %) or very well removed (>80 %) by sorption and volatilization. Some readily biodegradable molecules are better removed by CAS, indicating a better biodegradation. A better sorption of pollutants on activated sludge could be also expected considering the differences of characteristics between a biofilm and flocs. Finally, comparison of global processes efficiency using removals of micropollutants load normalized to nitrogen shows that PCLS + BF is as efficient as PS + CAS despite a higher compactness and a shorter hydraulic retention time (HRT). Only some groups of pollutants seem better removed by PS + CAS like alkylphenols, flame retardants, or di-2-ethylhexyl phthalate (DEHP), thanks to better biodegradation and sorption resulting from HRT and biomass characteristics. For both processes, and out of the 68 molecules found in raw water, only half of them are still detected in the water discharged, most of the time close to their detection limit. However, some of them are detected at higher concentrations (>1 μg/L and/or lower than environmental quality standards), which is problematic as they represent a threat for aquatic environment.

[Departement_IRSTEA]Ecotechnologies [TR1_IRSTEA]TED [Axe_IRSTEA]TED-EPURE | International audience | The Hydrus-2D software package allows to display the interaction of processes in constructed wetlands. Whereas several types of constructed wetlands were simulated successfully, the results for combined sewer overflow treatment wetlands are less satisfying so far. Main reasons can be found in the high variations of feeding characteristics as well as in extended dry periods of several weeks. In preparation of model improvements by considering organic filtrates as nutrient source in dry periods it seems to be essential to display hydraulics and solute transports correctly by tracer test studies. This was done in column experiments in the past, but not for full-scale constructed wetlands due to operational challenges. The given study shows tracer test results in pilot-scale operation in two different ways. Obtained measurement results were simulated with 1D and 2D approaches. Simulation results show the importance of considering inlet and outlet placement inside the filter beds correctly.

Mechanistic effect models for ecological risk assessment of chemicals (MEMoRisk)-a new SETAC-Europe Advisory Group

International audience

International audience | Surfactants are used for a variety of applications such as emulsifiers, solubilizers, or foaming agents. Their intensive production and use in pharmaceutical, cosmetic and agricultural products have resulted in their continuous discharge in the environment, especially via wastewaters. Surfactants have become a threat to living organisms as they interact with, and disrupt, cell membranes and macromolecules. Their effects have mainly been studied in aquatic species; however, terrestrial organisms are also threatened by these emerging contaminants. This study investigates the effects of two widely used nonionic surfactants, Tween-20 and Triton X-100, on key traits of larvae and adults of the fruit fly Drosophila melanogaster. We assessed the toxicity of the two surfactants on viability, development time, body size and food intake of the flies. The results revealed that both surfactants induced toxic effects on the drosophila flies leading to decreased viability, delayed development and lowered food consumption at the highest tested concentrations. Both surfactants proved to be toxic to flies, and, for all tested traits, Triton X-100 appeared more toxic than Tween-20. Our results might extend to other invertebrates. The widespread use of these substances, which then end up in the environment, should be regulated to mitigate their impacts on biodiversity and ecosystems.

International audience | Soil and the threats it faces nowadays are often underestimated by citizens. This is rather due to a lack of awareness than to a lack of interest. In France, the surface covered by private gardens is not negligible, as it represents 2% of the territory, which is four times larger than the area of natural reserves in the country. Therefore, ensuring the protection and preservation of healthy soils in these areas is of great importance. Citizen science is a good way to raise awareness about scientific issues. Using a scientific and educational approach, the citizen science project “La clé du sol,” funded by the Fondation de France coordinated by the evertéa Foundation, aimed to raise home gardeners’ awareness of soil complexity and how to maintain healthy soil, as well as help them realize the possible consequences of their practices. For 2 years, fourteen gardeners participated in the project which involved theoretical and practical workshops where cultivation practices were listed, garden soils were sampled, and their physico-chemical and biological parameters as well as contaminants were analyzed. The strength of this project was the close interaction between the gardeners, a local citizen association, agronomy students, and researchers to decipher and interpret the results and learn how to translate them into practical advice. The progress of the project is presented in this article. Moreover, the scientific, social, and educational contributions of “La clé du sol” as well as the challenges inherent in citizen science projects involving long-term citizen engagement will be discussed.

International audience | Road traffic is one of the main sources of particulate matter in the urban environment, emitting particulate organic and elemental carbon compounds and metal-rich particles through combustion and brakes and tires wear. In Western Africa, the carbon and metal composition of airborne particles is also influenced by additional sources linked to biomass combustionand recent industrialization. Here, we investigated the impact of combustion-related and non-combustion-related emissions on the distribution of carbonaceous fractions and iron-rich particles in two urban environments in France and Senegal. The supermicron fraction (Da > 1μm) showed a significantly higher isothermal remanent magnetization (SIRM) than finer fractions, accounting for 79% in France and 81% in Senegal of the total SIRM. In the submicron fraction (Da < 1μm), we noted significantly higher concentrations of total carbon (TC) and elemental carbon (EC) than for other fractions, both accounting for 71% in France and 68% and 75% in Senegal of the total and elemental particulate carbon concentration, respectively. Electron microscope observations revealed the presence of iron-rich particles for Da < 0.2μm, however, associated with a weak SIRM. Such iron particles may be produced by combustion or abrasion while we suspect that emissions by the abrasionprocess produce larger particles.