History of Atmospheric Lead Deposition Since 12,370 ~(14)C yr BP from a Peat Bog, Jura Mountains, Switzerland

摘要

A continuous record of atmospheric lead since 12,370 carbon-14 years before the present (~(14)C yr BP) is preserved in a Swiss peat bog. Enhanced fluxes caused by climate changes reached their maxima 10,590 ~(14)C yr BP (Younger Dryas) and 8230 ~(14)C yr BP. Soil erosion caused by forest clearing and agricultural tillage increased lead deposition after 5320 ~(14)C yr BP. Increasing lead/scandium and decreasing lead-206/lead-207 beginning 3000 ~(14)C yr BP indicate the beginning of lead pollution from mining and smelting, and anthropogenic sources have dominated lead emissions ever since. The greatest lead flux (15.7 milligrams per square meter per year in A.D. 1979) was 1570 times the natural, background value (0.01 milligram per square meter per year from 8030 to 5320 ~(14)C yr BP).