Lead isotope fingerprinting techniques help identify and quantify 3,000 years of atmospheric lead pollution from Laguna Roya, northwestern Iberia Supplemental

Until ~1960 CE the primary source of anthropogenic Pb in the Laguna Roya sediment record was atmospheric Pb pollution from distant, largescale metal refining in the SW. Dated slag Pb isotope ratios from the Rio Tinto mining district provided strong evidence to identify the source of Pb pollution in Laguna Roya sediments. The primary source of lake sediment Pb pollution after 1960 CE is metal processing from the SW mining district (~85%) whereas leaded gasoline contributes ~15%.