Past natural changes in Cu, Zn and Cd in Vostok Antarctic ice dated back to the penultimate interglacial period

Abstract

Improved ice core decontamination procedures have allowed us to obtain the first reliable data on Cu, Zn and Cd in ancient Antarctic ice drilled in a fluid filled hole at Vostok Station, dated back to the beginning of the next to last ice age similar to 240,000 years ago. Cu, Zn and Cd concentrations and fallout fluxes display very large natural variations by up to a factor of 35, with high values obtained during the coldest climatic stages and much lower values during warm climatic stages. Crustal dust was an important source of Cu and Zn during the coldest climatic stages, and volcanic emissions were probably an important source of Cd both during warm and cold periods.