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International audience; Over the course of history, the development of human societies implied the exploitation of mineral resources which generated huge amounts of mining wastes leading to substantial environmental contamination by various metal(loid)s. This is especially the case of coal mine tailings which, subjected to weathering reactions, produce acid mine drainage (AMD), a recurring ecological issue related to current and past mining activities. In this study, we aimed to determine the origin, the fate and the ecotoxicity of metal(loid)s leached from a historical coal tailing heap to the Beuveroux river (Franche-Comté, France) using a combination of mineralogical, chemical and biological approaches. In the constitutive materials of the tailings, we identified galena, tetrahedrite and bournonite as metal-rich minerals and their weathering has led to massive contamination of the water and suspended particles of the river bordering the heap. The ecotoxicity of the AMD has been assessed using Chironomus riparius larvae encaged in the field during a one-month biomonitoring campaign. The larvae showed lethal and sub-lethal (growth and emergence inhibition and delay) impairments at the AMD tributary and near downstream stations. Metal bioaccumulation and subcellular fractionation in the larvae tissues revealed a strong bioavailability of, notably, As, Pb and Tl explaining the observed biological responses. Thus, more than 70 years after the end of mining operations, the coal tailings remain a chronic source of contamination and environmental risks in AMD effluent receiving waters.

L'Ailante glanduleux (Ailanthus altissima (Miller) Swingle) est un arbre d'origine chinoise introduit en France durant la deuxième moitié du XVIIIe siècle. Il fut au départ planté en ville dans les espaces verts, puis fut l'objet d'une phase de plantation courte mais intensive dans l'objectif de produire de la soie. Il est aujourd'hui très répandu dans le milieu naturel et manifeste localement un comportement envahissant, notamment dans des forêts claires ou des pelouses. L'herbicide naturel et le nombre très élevé de fruits qu'il produit, mais aussi sa croissance rapide et sa faculté de reproduction végétative sous forme de drageons ou de rejets sont des caractéristiques biologiques essentielles pour permettre d'expliquer son caractère envahissant. Cet arbre offre des atouts variés mais le risque d'érosion de la biodiversité qu'il occasionne est à l'origine de recherche de méthodes pour son contrôle. Il serait sage de ne plus le planter et de surveiller sa répartition. / The tree of heaven (Ailanthus altissima (Miller) Swingle) originates from China and was introduced into France during the second half of the 18th century. It was initially planted in city parks and was later briefly but intensively grown for the purpose of producing silk. It is now widely disseminated in the natural environment and is locally invasive, especially in open forests and on grasslands. Its invasiveness is due to essential biological characteristics, i.e. the large quantity of fruit and natural herbicide it produces, its rapid vegetative growth in the form of suckers and shoots. Although this tree has some benefits, it also presents a risk of biodiversity degradation, which is why methods for control are being investigated. It would be wise to stop planting this tree and monitor its distribution.