Antarctic snow record of cadmium, copper, and zinc content during the twentieth century

A snowpit in Coats Land, Antarctica, has been sampled in order to obtain a record of Cd, Cu and Zn covering the period 1923–1986. The snowpit record gives an indication of southern hemisphere (SH) pollution reaching Antarctica. For Zn, concentrations (averaging 1.5 ng kg-1) can be explained as arising from natural crustal dust (based on Zn/Al ratios). No increase is observed over the period of the record here, despite a large increase in emissions from smelting operations. The main emitters are near the equator, and this may explain the lack of response in the Antarctic record. For Cd, concentrations (averaging 0.1 ng kg-1) cannot easily be explained in terms of natural emissions, unless the volcanic input is dominant. No significant increase is seen in the snow for this metal also. For Cu, the natural input can explain only a small part of the concentration (averaging 3.5 ng kg-1) measured, and increased concentrations (factor 2) are seen in the 1970s and 1980s compared to earlier decades. This is consistent with increased emissions from Cu smelting activities, particularly in Chile, where emissions are relatively far south compared to the main part of SH landmasses. Cu thus joins Pb as a metal whose natural cycle has been significantly perturbed even in the Antarctic atmosphere.