A European lead isotope signal recorded from 6000 to 300 years BP in coastal marshes (SW France)

Cores covering the last 6000 years were recovered from two marshes from sou th-western France. They were studied in an attempt to build a reliable regi onal record of heavy metal pollution. The cores were dated using C-14 and h istorical data. Both Pb concentrations and Pb isotopic composition (Pb-206/ Pb-207 and Pb-208/Pb-206) were measured in bulk sediment samples using the inductively coupled plasma-mass spectrometer technique. The evolution of th e Pb-206/Pb-207 ratio recorded in both marshes reveals a good correlation w ith the worldwide Pb production during the last 5000 years. The lead isotop ic records reveal some general trends, along with a few typical events such as the imprints of the pre-anthropogenic background between 6000 and 2300 years BP, the mining activity during the Roman and Creek periods from 2300 to 1700 years BP, the fall of the Roman Empire and the mining activity in C entral Europe since the 11th century AD. These results are also consistent with records obtained in other European environments. Consequently, the Eur opean atmospheric signal is recorded in these marshes, hiding expected loca l riverine contributions. Thus, such records may contribute to the construc tion of a chronological standard curve for continental environments. Howeve r, it will be necessary to study other records more accurately dated to obt ain an adequate precision before such a reference curve can be set-up. (C) 2001 Elsevier Science Ltd. All rights reserved.