Le Marais des Paluns

Les zones humides méditerranéennes sont au cœur de multiples enjeux environnementaux. Les zones humides de la Palun connectées à l’étang de Berre sont une zone spéciale de conservation située à l’aval d’un bassin versant anthropisé. Une contamination diffuse et cumulative dans le temps des sédiments y a été identifiée. C’est dans ce contexte qu’un travail a été mené sur un procédé de traitement des eaux du bassin versant de la Palun pour favoriser la résilience du marais récepteur face à la pollution chronique. Les possibilités de réalisation d’une zone humide artificielle en amont du marais, dédiée à l’épuration des eaux, ont été réfléchies en lien avec les usages et les attentes parfois divergentes des acteurs du territoire. La réparation des atteintes environnementales dans le contexte socio-économique contraint de l’étang de Berre a été interrogée à partir des savoirs issus de l’écologie de la restauration et de la sociologie.Mediterranean wetlands are subject to many environmental issues. The Palun wetlands in connection with the industrialized Berre lagoon are a special area of conservation located downstream of an anthropised watershed and where diffuse and cumulative contaminations of the sediments were detected. A work was then carried out on a water treatment process in the Palun watershed to promote the resilience of the receiving marsh. The possibilities of creating a constructed wetland upstream to treat all waters have been reflected in connection with the potential divergent uses and expectations of the territory actors. Repairing environmental damages in the particular socio-economic context of the Berre lagoon was considered from the knowledge of restoration ecology and sociology

Phytoremediation of mixtures of organic and metallic contaminants for Mediterranean wetlands protection : an exploratory approach for the development of ecological engineering tools.

L'objectif de la thèse était de développer un système de phytoépuration par marais artificiels permettant le traitement simultané de micropolluants organiques (MPO) et d'éléments traces métalliques et métalloïdes (ETMM) en milieu méditerranéen, en vue de traiter les rejets émis par un bassin versant industrialisé, et favoriser la résilience d'une zone humide protégée. Une étude en microcosmes a été conduite sur cinq hélophytes (Alisma lanceolatum, Carex cuprina, Epilobium hirsutum, Iris pseudacorus, et Juncus inflexus) natives du marais des Paluns (Marignane, 13). La croissance et le développement des plantes ont été suivis pendant 113 jours d'exposition à des mélanges de MPO et/ou d'ETMM, à des concentrations maximales dix fois plus élevées que les seuils de rejets réglementaires. Les concentrations en ETMM dans les parties souterraines et aériennes des plantes ainsi que les communautés bactériennes de la rhizosphère ont été analysées à la fin de l'étude. Les résultats ont confirmé l'efficacité épuratoire du système et ont permis de mieux comprendre les interactions entre plantes, substrat, polluants et microorganismes. Les résultats encouragent l'utilisation de C. cuprina pour la phytoaccumulation et la phytostimulation, et d'E. hirsutum pour la bioindication. Afin de faciliter l'intégration du marais artificiel au sein du territoire industrialisé, un outil de bioindication a été développé, en complément d'une approche sociologique. La thèse a abouti à la mise en place de trois éco-filtres expérimentaux, en amont du marais des Paluns, permettant de tester en conditions réelles les outils développés et de constituer un site pilote pour le bassin méditerranéen.The thesis aimed at developing a constructed wetland for simultaneous phytoremediation of organic micropollutants (OPM) and trace metals and metalloids (MM) in Mediterranean environment, for treating chronical and accidental releases from an industrialized catchment, and enhancing the resilience of a protected wetland. A greenhouse study was conducted in microcosms with pozzolan substrate, with five native helophytes (Alisma lanceolatum, Carex cuprina, Epilobium hirsutum, Iris pseudacorus, and Juncus inflexus) from the "Les Paluns" wetland (Marignane, 13). Plant growth and development parameters were monitored during 113 days of exposure to mixtures of OPM and/or MM, with the maximum concentrations ten times over the limits of European quality standards. MM concentrations in belowground and aboveground plant parts and rhizosphere bacterial communities were analyzed at the end of the study. Results confirmed the system depurative efficiency and provided an insight into the interactions between plants, substrate, pollutants and microorganisms, and an assessment of their effects on phytoremediation processes. Results encourage the use of C. cuprina for MM phytoaccumulation and for phytostimulation, and of E. hirsutum as a bioindicator in constructed wetlands. Finally, a bioindication tool was created to assist the constructed wetland integration in the industrialized territory, as a complement of a sociological approach. The thesis led to the implementation of three experimental eco-filters upstream from the Les Paluns wetland, in order to test in naturae the tools developed and to have a pilote site for the Mediterranean basin

Potentiels d’utilisation des macrophytes pour réduire l’impact des industries sur les milieux aquatiques européens

International audienceLes macrophytes sont de plus en plus exploités pour atteindre les bons états chimique et écologique recommandés des masses d’eau européennes. Mais quelles sont les particularités des macrophytes en tant qu’outil de bio-surveillance ? Et quelles nouvelles informations sont apportées par la recherche quant à leur potentiel de réduction d’écotoxicité

Note - Potentiels d’utilisation des macrophytes pour réduire l’impact des industries sur les milieux aquatiques européens

Les macrophytes sont de plus en plus exploités pour atteindre les bons états chimique et écologique recommandés des masses d’eau européennes. Mais quelles sont les particularités des macrophytes en tant qu’outil de bio-surveillance ? Et quelles nouvelles informations sont apportées par la recherche quant à leur potentiel de réduction d’écotoxicité

Potentiels d’utilisation des macrophytes pour réduire l’impact des industries sur les milieux aquatiques européens

International audienceLes macrophytes sont de plus en plus exploités pour atteindre les bons états chimique et écologique recommandés des masses d’eau européennes. Mais quelles sont les particularités des macrophytes en tant qu’outil de bio-surveillance ? Et quelles nouvelles informations sont apportées par la recherche quant à leur potentiel de réduction d’écotoxicité

Le Marais des Paluns Analyse de ses usages et de son état environnemental pour contribuer à une réflexion sur sa restauration écologique

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Constructed wetlands to reduce metal pollution from industrial catchments in aquatic Mediterranean ecosystems: A review to overcome obstacles and suggest potential solutions

International audienceIn the Mediterranean area, surface waters often have low discharge or renewal rates, hence metal contamination from industrialised catchments can have a high negative impact on the physico-chemical and biological water quality. In a context of climate and anthropological changes, it is necessary to provide an integrative approach for the prevention and control of metal pollution, in order to limit its impact on water resources, biodiversity, trophic network and human health. For this purpose, introduction of constructed wetlands (CWs) between natural aquatic ecosystems and industrialised zones or catchments is a promising strategy for eco-remediation. Analysis of the literature has shown that further research must be done to improve CW design, selection and management of wetland plant species and catchment organisation, in order to ensure the effectiveness of CWs in Mediterranean environments. Firstly, the parameters of basin design that have the greatest influence on metal removal processes must be identified, in order to better focus rhizospheric processes on specific purification objectives. We have summarised in a single diagram the relationships between the design parameters of a CW basin and the physico-chemical and biological processes of metal removal, on the basis of 21 mutually consistent papers. Secondly, in order to optimise the selection and distribution of helophytes in CWs, it is necessary to identify criteria of choice for the plant species that will best fit the remediation objectives and environmental and economic constraints. We have analysed the factors determining plant metal uptake efficiency in CWs on the basis of a qualitative meta-analysis of 13 studies with a view to determine whether the part played by metal uptake by plants is relevant in comparison with the other removal processes. Thirdly, we analysed the parameters to consider for establishing suitable management strategies for CWs and how they affect the whole CW design process. Finally, we propose monitoring and policy measures to facilitate the integration of CWs within Mediterranean industrialised catchments

Biomonitoring of Epilobium hirsutum L. Health Status to Assess Water Ecotoxicity in Constructed Wetlands Treating Mixtures of Contaminants

For the treatment of wastewater containing organic pollutants and metals in constructed wetlands (CWs), phytoindicators may help in guiding management practices for plants and optimizing phytoremediation processes. Hairy willow-herb (Epilobium hirsutum L.) is a fast growing species commonly found in European CWs that could constitute a suitable phytoindicator of metal toxicity. E. hirsutum was exposed for 113 days in microcosm CWs, to a metal and metalloid mixture (MPM, containing Al, As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Sn, Zn), an organic pollutant mixture (OPM, containing hydrocarbonsC10-C40, phenanthrene, pyrene, anionic detergent LAS) and an organic pollutant and metal and metalloid mixture (OMPM), separately and at concentration levels mimicking levels of industrial effluents. Analyses of metal and As concentrations in biomass, and different biometric and physiological measurements were performed. Results showed that metal uptake patterns were affected by the type of pollutant mixture, resulting in variation of toxicity symptoms in E. hirsutum plants. Some of them appeared to be similar under MPM and OMPM conditions (leaf chlorosis and tip-burning, decrease of green leaf proportion), while others were characteristic of each pollutant mixture (MPM: Decrease of water content, increase of phenol content; OMPM: reduction of limb length, inhibition of vegetative reproduction, increase of chlorophyll content and Nitrogen balance index). Results emphasize the potential of E. hirsutum as a bioindicator species to be used in European CWs treating water with metal, metalloid and organic pollutants

Selection of wild macrophytes for use in constructed wetlands for phytoremediation of contaminant mixtures

International audienceConstructed wetlands (CWs) offer an alternative to traditional industrial wastewater treatment systems that has been proved to be efficient, cost-effective and environmentally friendly. Most of the time, CWs are planted with proliferative species such as Phragmites australis or with plants originating from nurseries, both representing a risk for the natural biodiversity conservation of aquatic ecosystems located downstream of the CWs. For the removal of metals and organic pollutant mixtures present in industrial effluents, it is necessary to select tolerant plant species that are able to produce a high aboveground biomass and to develop a healthy belowground system. Wild plant species growing in aquatic bodies at industrial outfalls could constitute suitable tolerant species to use in CWs for industrial effluent treatment. To test this hypothesis, we assessed, under laboratory conditions (using an experimental design), the tolerance to mixtures of metals (Al, As, Cd, Cu, Cr, Fe, Mn, Ni, Pb, Sn, Zn) or/and organic pollutants (THC, PHE, PYR, LAS) of five European sub-cosmopolitan native macrophytes (Alisma lanceolatum, Carex cuprina, Epilobium hirsutum, Iris pseudacorus and Juncus inflexus) that had been collected in a polluted Mediterranean wetland, after a field study (crossing ecological releves and analyses of contaminant concentrations in water and sediments). Our results demonstrated that research on phytoremediation of industrial effluents should focus much more on the use of native macrophytes growing at short distances from industrial discharges (such as C cuprina in this study), and that root/shoot ratio, aerial height and proportion of green leaves are good and cost-effective indicators of plant tolerance to metals and organic pollutant mixtures in laboratory studies. (C) 2014 Elsevier Ltd. All rights reserved

Proposal of a new ecotoxicity evaluation tool based on morphological responses of five helophytes to mixtures of pollutants: The Helophyte Development Index

International audienceIndustrial effluents discharged into the environment may have ecotoxic effects even if they come up to regulatory standards. Chemical evaluation of treatment performance by end-of-pipe treatment systems is thus not sufficient, especially when mixtures of metallic and organic contaminants are concerned. Given that contamination may alter biological characteristics of the environment, biomonitoring studies may provide information on integrated ecotoxical effects. However, there is a need for bioassays purpose-designed for direct use at industrial sites. Many biomonitoring tools already exist and have been proved to be efficient for evaluating the ecotoxicity of contaminated waters, but most of them require laboratory equipment. In this study, an experiment in microcosms under controlled conditions of pollution was carried out to assess the morphological responses of five helophytes exposed to mixtures of organic and/or metallic pollutants. The criteria of plant growth and development, i.e. aerial elongation and leaf senescence, that were the most relevant for reflecting the ecotoxicity of contaminant mixtures and that could be monitored on-site with a user-friendly method, were then selected. Focusing on these selected criteria, a new bioindicator tool, named the Helophyte Development Index (HDI), was created. Our results suggest that the HDI is a promising tool to use on-site for assessing the ecological state of waters released in aquatic environment by industrial factories, following the recommendations of the European Water Agency. (C) 2015 Elsevier B.V. All rights reserved