Changes in zinc and cadmium concentrations in Greenland ice during the past 7760 years

Analysis of Zn and Cd in Greenland Holocene ice dated from 7760 to 471 yr ago shows no significant changes during the Greek, Roman and medieval times. It indicates that emissions from early mining and smelting operations were not intense enough for these two metals to have left detectable signals in Greenland ice above natural background, contrary to what was previously observed for Pb and Cu. Zn was especially used during Antiquity to make brass, the important binary Cu---Zn alloy which was probably produced as early as 4000 yr ago. Rock and soil dust and continental biogenic sources are found to be important contributors to natural Zn and Cd in Holocene Greenland ice. During periods without major volcanic events, contribution from volcanoes was probably insignificant for Zn but could be important for Cd.