Influence de l’historique d’usage des sols : les jardins de Nantes

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Méthodes de conception et de monitoring pour évaluer les performances des noues

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Infiltration et épuration des eaux pluviales en milieu urbain : étude sur un dispositif pilote

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Transfert de nanoparticules en milieu poreux hétérogène

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Caractérisation des nanoparticules des eaux de ruissellement et transfert dans les milieux poreux hétérogènes

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Bimodal breakthrough curves through dual-permeability systems: an experimental and numerical study

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Polluants émergents des eaux pluviales dans les bassins d'infiltration : transfert de nanoparticules en milieu poreux hétérogène

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Interplay between Molecular Diffusion and Advection during Solute Transport in Macroporous Media

International audienceSolute transport in soils is known to differ from solute transport in homogeneous porous media. Nonequilibrium processes, like those induced by the presence of macropores, can strongly influence the breakthrough of solute in soils. Breakthrough experiments and effective models are often combined to study the physicochemical processes involved in solute transport. However, the complexity of flow pathways and the diversity of possible processes is challenging. In this work, the influence of flow rate and viscosity of the carrying liquid on nonreactive solute transport is investigated under saturated conditions in a macroporous synthetic medium. As expected, solute transport is strongly affected by physical nonequilibrium induced by the preferential flow within the macropore. Breakthrough occurs early, and the shape of the breakthrough curve is influenced both by the flow rate and the coefficient of molecular diffusion of the solute. We show that when the mean residence time of the solute in the macropore is small enough, solute transport in a macroporous column can be considered as isolated within the macropore. The increase of the residence time strongly affects the shape of the breakthrough, and, eventually, a plateau appears during the ascent of the breakthrough curve. We demonstrate experimentally that the existence of this plateau, which is not predicted by classical effective models, is related to the relative importance of molecular diffusion versus advection. Indeed, this plateau can become unobservable if the coefficient of molecular diffusion is reduced through the use of a sufficiently viscous carrying liquid

Potential of Aquatic Macrophytes as Bioindicators of Heavy Metal Pollution in Urban Stormwater Runoff

International audienceThe concentrations of heavy metals in water, sediments, soil, roots, and shoots of five aquatic macrophytes species (Oenanthe sp., Juncus sp., Typha sp., Callitriche sp.1, and Callitriche sp.2) collected from a detention pond receiving stormwater runoff coming from a highway were measured to ascertain whether plants organs are characterized by differential accumulations and to evaluate the potential of the plant species as bioindicators of heavy metal pollution in urban stormwater runoff. Heavy metals considered for water and sediment analysis were Cd, Cr, Cu, Ni, Pb, Zn, and As. Heavy metals considered for plant and soil analysis were Cd, Ni, and Zn. The metal concentrations in water, sediments, plants, and corresponding soil showed that the studied site is contaminated by heavy metals, probably due to the road traffic. Results also showed that plant roots had higher metal content than aboveground tissues. The floating plants displayed higher metal accumulation than the three other rooted plants. Heavy metal concentrations measured in the organs of the rooted plants increased when metal concentrations measured in the soil increased. The highest metal bioconcentration factors (BCF) were obtained for cadmium and nickel accumulation by Typha sp. (BCF = 1.3 and 0.8, respectively) and zinc accumulation by Juncus sp. (BCF = 4.8). Our results underline the potential use of such plant species for heavy metal biomonitoring in water, sediments, and soil

Socio-economic and socio-ecological benefits of allotment gardens – findings from case studies in France, Poland and Germany

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