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Legacy pollution in the contemporary environment – From old mines to young trout
Sophia V. Hansson
EcoLab, Université de Toulouse
Jeudi 09/03/2017, 11h00-12h00
Bat 12, Bibliothèque, LSCE Gif-sur-Yvette

Although we largely associate impacts from mining on surrounding environment with the industrial era, historical mining has a millennial scale history leaving a long-lasting imprint on the environment. Pollution from pre-industrial times caused by mining activities such as ore exploitation and processing, when there were few if any environmental controls, could be substantial. Results on trace metal concentrations in the Central Pyrenees, where extensive mining (Ag, Fe) occurred from the Antiquity to the 19th century, indicates that ≥600 tons of anthropogenic lead (Pb) is stored in peat and organic soils in the Haut-Vicdessos area. The Pb-isotopic signature measured in soils, peat bogs and sediments indicates various sources of Pb deposition; i.e. both natural sources and from mining activities during the Antiquity, medieval and recent periods, but also Pb lead derived from industrial and vehicle/transportation sources. The effects of this legacy pollution can also be seen in the contemporary freshwater aquatic food chain. Based on geochemical data, i.e. total concentration and isotopic signatures of Pb in brown trout (Salmo Trutta) and common minnow (Phoxinus phoxinus) caught at five sites and in three different adjacent valleys, we found that although mining in the area ceased over 100 years ago, trout and their prey still show a large range of Pb isotopic signatures including both modern deposition and mining related Pb. This reflects the long human-environment interaction in this mountain environment and that legacy pollution have a long-lasting impact even after activities have ceased.

Contact : Aline Govin
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