Changes in the natural lead, cadmium, zinc, and copper concentrations in the Vostok Antarctic ice over, the last two glacial-interglacial cycles (240,000 years)

We present new ice core records showing the temporal variation in the natural Pb, Cd, Zn, and Cu concentrations in the Vostok Antarctic ice over the past 240,000 years. Our data show that concentrations of these heavy metals have varied remarkably over the last two glacial-interglacial cycles. The concentrations ranged from 0.9 to 21.3, 0.04 to 0.62, 3.12 to 126, and 2.27 to 37.4 pg/g for Pb, Cd, Zn, and Cu, respectively. These profiles provide a better understanding of climate-related variation in the occurrence of these heavy metals in ancient Antarctic ice. The concentrations were much higher during cold glacial periods than during interglacials, and peaked at the coldest glacial stages. The contribution of rock and soil dust is estimated to be close to the measured concentrations of Pb, Zn, and Cu, but not Cd, in the ice during cold glacial periods

Glacial-interglacial changes in the occurrence of Pb, Cd, Cu and Zn in Vostok Antarctic ice from 240 000 to 410 000 years BP

International audienceLead (Pb), cadmium (Cd), copper (Cu) and zinc (Zn) have been measured by electrothermal atomic absorption spectrometry in various sections of the 3623 m deep ice core drilled at Vostok, in central East Antarctica. The sections were dated from 240 to 410 kyear BP (Marine Isotopic Stages (MIS) 7.5 to 11.3), which corresponds to the 3rd and 4th glacial-interglacial cycles before present. Concentrations are found to have varied greatly during this 170 kyear time period, with high concentration values during the coldest climatic stages such as MIS 8.4 and 10.2 and much lower concentration values during warmer periods, such as the interglacials MIS 7.5, 9.3 and 11.3. Rock and soil dust were the dominant sources for Pb, whatever the period, and for Zn and Cu and possibly Cd during cold climatic stages. The contribution from volcanic emissions was important for Cd during all periods and might have been significant for Cu and Zn during warm periods

Antarctic surface temperature and elevation during the Last Glacial Maximum

Water-stable isotopes in polar ice cores are a widely used temperature proxy in paleoclimate reconstruction, yet calibration remains challenging in East Antarctica. Here, we reconstruct the magnitude and spatial pattern of Last Glacial Maximum surface cooling in Antarctica using borehole thermometry and firn properties in seven ice cores. West Antarctic sites cooled ~10°C relative to the preindustrial period. East Antarctic sites show a range from ~4° to ~7°C cooling, which is consistent with the results of global climate models when the effects of topographic changes indicated with ice core air-content data are included, but less than those indicated with the use of water-stable isotopes calibrated against modern spatial gradients. An altered Antarctic temperature inversion during the glacial reconciles our estimates with water-isotope observations. © 2021 American Association for the Advancement of Science. All rights reserved