29 research outputs found

    Lanthanide ecotoxicity: First attempt to measure environmental risk for aquatic organisms

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    International audienceThe geochemical cycles of lanthanides are being disrupted by increasing global production and human use, but their ecotoxicity is not fully characterized. In this study, the sensitivity of Aliivibrio fischeri and Pseudokirchneriella subcapitata to lanthanides increased with atomic number, while Daphnia magna, Heterocypris incongruens, Brachionus calyciflorus and Hydra attenuata were equally sensitive to the tested elements. In some cases, a marked decrease in exposure concentrations was observed over test duration and duly considered in calculating effect concentrations and predicted no effect concentrations (PNEC) for hazard and risk assessment. Comparison of PNEC with measured environmental concentrations indicate that, for the present, environmental risks deriving from lanthanides should be limited to some hotspots (e.g., downstream of wastewater treatment plants). However, considering the increasing environmental concentrations of lanthanides, the associated risks could become higher in the future. Ecotoxicological and risk assessment studies, along with monitoring, are required for properly managing these emerging contaminants

    Effect of PAC (PAH & Polar-PAC) availability on terrestrial organisms’ ecotoxicity

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    International audienceHistorically contaminated sites have gained attention in recent decades. Some of them, e.g., former coking plants are contaminated by polycyclic aromatic compounds (PACs), including PAHs and polar-PACs (O/N/S-PACs). PACs are known to be toxic to soil organisms [1]. The exposure of terrestrial organisms to freshly contaminated soil with PAHs and polar-PACs demonstrated significant toxicity towards several organisms.However, for some soils sampled from historically contaminated sites exhibiting a higher PAC content, tests performed on earthworms have shown a limited impact on mortality rates [2]. As reported by several studies, in historically contaminated sites, PAC (bio)availability is generally limited. This phenomenon known as "aging" [3,4], is a main factor to consider in the evaluation of toxicity risk in soil contaminated by PAC [5]. In fact, for a refined estimation of the environmental risk and understanding of the impact of the PAC (bio)availability on toxicity, it is neccesery to combine a complete chemical characterization (total content and available fraction of PACs) and biological expositions [6].This work aims to evaluate the toxicity of two aged coking plant soils by running bioassays on invertebrates and plants. The toxicity of these soils (low PAC availability) will be compared with the same soils previously treated (heating) to increase their PAC availibility.A pre-heating treatment was carried out in order to increase PAC availability [5], then the soil was extracted with dichloromethane (DCM) and the PACs (i.e., PAHs and O/N/S PACs) were quantified by GC-MS. As a second step, ecotoxicity tests were performed through limit assays using acute bioassays. The purpose of this step is to evaluate the earthworm viability rate and seed development of plants (seedling emergence and growth) and to highlight the importance of taking into account the availability factor.Results of this study showed that soils with identical physico-chemical properties but exhibiting contrasted levels of PAC availability induced different ecotoxic responses of terrestrial organisms, an increased availability leading to a much higher toxicity. These results pointed out the importance of considering the contamination availability parameter in risk assessment and not only the total contaminant concentration.References: [1] Wang et al. (2022) Environmental Challenges, 9, 100613.[2] Eom et al. (2007), Ecotoxicology and Environmental Safety, 67(2),190-205[3] Fernández et al. (2005), Ecotoxicology and Environmental Safety, 62(2), 174-184[4] Boulangé et al. (2019) Chemosphere 224: 437‑44. [5] Biache, C. et al. (2021) Talanta 228: 122235.[6] Juvonen et al. (2000), Ecotoxicology and Environmental Safety,47(2), 156-16

    Effect of polycyclic aromatic compound (PAH & Polar-PAC) availability on their ecotoxicity towards terrestrial organisms

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    International audienceThe exposure of terrestrial organisms to soils freshly contaminated by polycyclic aromatic compounds (PACs, including PAHs and polar-PACs) is known to cause significant toxicity effects. However, historically contaminated soils, such as former coking plant soils, usually induce a limited toxic impact, due to the "aging" phenomenon which is the result of several processes causing a reduction of PAC availability over time. For a better understanding of these behaviors, this study aimed to compare the toxic responses of terrestrial organisms exposed to aged contaminated soils and their counterparts submitted to a moderate heating process applied to increase PAC availability. Two aged "raw" soils (limited PAC availability) were selected for their representativeness of former industrial soils in terms of PAC contamination. These soils were submitted either to moderate heating (expected PAC availability increase) or solvent-extraction (expected PAC removal). Physico-chemical parameters, contamination levels and availability were determined for these three soil modalities. Additionally, standardized limit bioassays on plants and earthworms were performed to assess soil ecotoxicity. The findings demonstrated that historically contaminated soils exposed to moderate heating exhibited the highest ecotoxic responses in terrestrial organisms. Heating increased PAC (bio)availability, without modifying any other soil physicochemical properties. These results pointed out the importance of considering the contamination availability parameter in risk evaluation and also provide a possible tool for protective long-term risk assessment

    Rôle de la disponibilité des composés aromatiques polycycliques de sols historiquement contaminés dans la réponse écotoxique d’organismes terrestres

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    International audiencePlus de 300 000 sites potentiellement impactés par des Hydrocarbures Aromatiques Polycycliques (HAP) ont été recensés en Europe, dont plus de 1 500 en France (BASOL). Le diagnostic et le suivi de ces sites se fait généralement par la quantification des composés réglementés (16 HAP US-EPA) sans toutefois tenir compte de leur disponibilité et de la présence de contaminants apparentés tels que les composés aromatiques polycycliques (CAP) polaires. L’exposition d’organismes terrestres à des sols fraîchement contaminés par les HAP ou les CAP polaires, est connue pour provoquer des effets toxiques importants. Cependant, les sols historiquement contaminés, comme les sols d’anciennes cokeries, induisent généralement un impact toxique limité, en raison du phénomène de « vieillissement » (ou « aging »), entraînant une réduction de la disponibilité des CAP dans le temps. La disponibilité est donc un paramètre crucial à prendre en compte lors de l’évaluation des risques associés à une contamination au CAP. L’objectif de cette étude est de mieux comprendre le rôle de la disponibilité des CAP d’un sol historiquement contaminé dans la réponse toxique d’organismes terrestres. Ainsi, deux sols historiquement contaminés ayant subis un « vieillissement » naturel (disponibilité en CAP limitée), ont été étudiés. Ces sols ont été modifiés pour (i) augmenter la disponibilité de la contamination (chauffage modéré) ou (ii) éliminer la pollution (extraction solvant). Les modalités « brutes » et « chauffées » permettent de comparer des niveaux de disponibilité différents tandis que les sols extraits constituent des références sans contaminant. Les paramètres physico-chimiques, les niveaux de contamination et la disponibilité ont été déterminés pour ces trois modalités de sol. En parallèle, des tests d’écotoxicité standardisés (plantes et vers de terre) ont été réalisés sur les sols bruts, chauffés et extraits. Les résultats ont démontré que les sols historiquement contaminés exposés à un chauffage modéré présentaient les réponses écotoxiques les plus élevées. En effet, le chauffage a permis d’augmenter la (bio)disponibilité des CAP, sans modifier les autres propriétés physico-chimiques du sol, ce qui permet d’imputer directement les effets toxiques observés à l’augmentation de la disponibilité. Ces résultats soulignent l’importance de prendre en compte ce paramètre dans l’évaluation des risques. Ils suggèrent, par ailleurs, que la méthode de chauffage modéré constitue un outil possible pour une évaluation des risques à long terme associés aux sols historiquement contaminés plus protectrice pour l’environnement et la santé humaine, qui peut s’avérer pertinente dans le contexte de changement climatique actuel

    Field evaluation of the cotton-strip assay for quantifying decomposition rates in extensive green roof substrates

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    International audienceExtensive green roof (EGR) substrates and vegetation layer are critical components to ensure EGR multi-functionality. However, little is known on EGR substrate biological functioning, especially nutrient cycling that iscrucial for supporting life in soils. This work aimed at investigating for the first time the effectiveness of anaffordable and easy-to-use standardized method, the cotton-strip assay, to assess decomposition rates in ten-year old EGR. Three metrics were evaluated following 34–110 days of cotton-strip incubation into substrates: tensile strength, weight and surface area losses. Tensile strength loss was the most sensitive index after 34 days while weight loss over 110 days confirmed elevated decomposition rates in EGR substrates compared to gravel rooftop or common urban park soil. This could be related to positive influence of slightly acidic pH and vegetation cover.Finally, semi-intensive but thin green roof substrates may be an alternative to intensive ones to sustain ecologicalprocesses supporting long-term vegetation growth, as long as there is no net carbon loss. Moreover, broaderassessment of decomposition into different green roof substrates configurations could pave the way for a betterunderstanding of green roof ecosystems as a whole and the design of more resilient green infrastructures

    Photocatalytic degradation of atrazine by an N-doped TiO2/polymer composite: catalytic efficiency and toxicity evaluation

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    International audienceMonolithic composite aerogel based on N-doped TiO2 (NdT) photocatalyst dispersed into syndiotactic polystyrene (sPS) matrix was used for atrazine (ATZ) degradation under ultra-violet (UV) and visible light (Vis) irradiation. sPS/NdT composite aerogel, with a polymer/photocatalyst 90/10 wt ratio, was achieved by super critical CO2 extraction of chloroform from the relative sPS/NdT gel. Testing of the sPS/NdT photocatalytic activity was performed by using initial ATZ concentration of 0.1 mg/L and a sPS/NdT composite in monolithic aerogel form. ATZ removal was equal to 47% and 25% under UV or Vis light, respectively, after 180 min of irradiation. The efficiency of the photocatalytic process was also investigated by monitoring the ecotoxicity of the treated water to Aliivibrio fischeri, Raphidocelis subcapitata, and Daphnia magna. The results indicated that, for both UV and Vis irradiation, even for high ATZ removal efficiency (i.e., UV treatment), the toxicity of process effluent is greater than the initial one, most likely because of the generation of toxic by-products. The UV treatment was effective only after 72 h when the solution appeared not toxic to D. magna and presented a very low effect to R. subcapitata. On the other hand, under Vis light irradiation, a very high level of toxicity was still detected after 72 h of treatment time. Toxicity tests are confirmed as an indispensable tool for a correct assessment of the environmental impact of water treatment processes

    Ecotoxicity of lanthanides to Daphnia magna: insights from elemental behavior and speciation in a standardized test medium

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    International audienceLanthanides (LNs) are a group of 15 elements with steadily increasing economical importance due to their multiple uses in technologies essential for sustainable ecological, digital and energetic transitions. Although knowledge on LN ecotoxicology has greatly improved over the last decade, uncertainty persists with regard to their actual hazard and risk in freshwater environments. In particular, only limited information is available on i) the actual relationships between LN speciation vs. ecotoxicological responses in standardized laboratory tests and ii) the existence of regular and predictable patterns in LN ecotoxicity (expressed as e.g., EC50) along the LN series. The present paper provides the first report on the ecotoxicity of all lanthanides (except Pm) for the freshwater crustacean Daphnia magna along with an unprecedented level of detail on LN speciation in the exposure medium. Experimental data show that exposure concentrations can decrease by up to 95 % over the test duration, with the percentage decrease being inversely related with LN atomic mass. Thermodynamic speciation calculations confirm the possible formation of insoluble species, mainly LN carbonates. However, the corresponding theoretical solubility limits do not fully agree with measured concentrations at the end of the tests. Experimental verification of exposure concentrations (as a minimum at the beginning and end of laboratory tests) remains therefore mandatory to reach proper conclusions as to the ecotoxicity of each LN. A decreasing trend in ecotoxicity can actually be observed along the LN series when temporal changes in the exposure concentrations are properly accounted for. However, this trend remains dependent on exposure time and selected exposure metrics. This and other caveats must be considered in future research to reach a community-based consensus for the proper hazard and risk assessment of LN towards daphnids and other aquatic organisms
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