Résumé
The present study aims to document early mining and smelting activities by means of geochemical and pollen analyses performed in a peat-bog core collected around the Bibracte oppidum (Morvan, France), the largest settlement of the great Aeduan Celtic tribe (ca 180 BC -25 AD). The anthropogenic Pb profile indicates local mining operations starting from the Late Bronze Age, ca cal. 1400-1300 BC. Lead inputs peaked at the height of Aeduan civilization, and then decreased after the Roman conquest of Gaul, when the site was abandoned. Other phases of mining are recognised from the 11th century to Modern Times. They have all led to modifications in plant cover, probably related in part to forest clearances necessary to supply energy for mining and smelting. Zn, Sb, Cd and Cu distributions may result from diffusional and biological processes and underlying mineral soil, precluding their interpretation for historical reconstruction. The abundance of mineral resources, in addition to the strategic location, might explain why early settlers founded the city of Bibracte at that particular place. About 20% of the anthropogenic lead record was accumulated before our era and about 50% before the 18th century, which constitutes a troublesome heritage. Any attempts to develop control strategies in accumulating environments should take into account past human activities in order to not overestimate the impact of contemporary pollution.