Abstract
Concentrations of trace metals and metalloids (Cu, Hg, Sb, Pb), major elements, stable Pb and C isotoperatios, total organic carbon (TOC), C/N atomic ratios, were analyzed in two sediment cores encompassing10,000 years of sedimentation sampled in Lake Robert (French Alps).The results showed that the establishment of a soil cover and vegetation during the Holocene climaticoptimum increased Cu and Hg deposition in sediments. Results also enabled reconstruction of the historyand local vs regional origins of pollution. During the Bronze Age (1800e1000 BC), Cu mining activitiesincreased Hg and Sb accumulation rates (AR) by a factor of 7 (Hg) and 9 (Sb) compared to pre-Bronze Agevalues. The rise in Hg AR was equivalent to that of the industrial era highlighting a major local Hg pointsource not recorded in regional archives. During the Iron Age, Pb pollution was attributed to Sicilian oreswhereas during the Roman Empire Pb pollution had the isotopic signature of Spanish Pb ores. During theMedieval period (ca. AD 1200), Pb and Hg pollution was due to the exploitation of the local AgePb mines.Finally, during the industrial era, metal accumulations rates were 90 (Pb), 5 (Hg) and 20 (Sb) times higherthan those in the pre-Bronze Age. The isotopic composition of Pb reflected mixed sources includingindustrial Pb and gasoline Pb. Synchronously, the increase in Sb and Hg pollution is attributed to globaland regional atmospheric pollution.