Elemental and Pb isotopic evidence for different interglacial climates before and after the Mid-Brunhes Event (~430 kyr BP) in the EPICA Dome C ice core

초록

We present here preliminary data on past changes in the occurrence of various trace elements and Pb isotopic composition in the European Project for Ice Coring in Antarctica (EPICA) Dome C ice core over the time period between Marine Isotope Stage (MIS) 15, ~570 kyr BP, and MIS 20.2, ~800 kyr BP. Our data profiles are compared with those available along the EPICA Dome C ice core back to ~200 kyr BP to characterize climate-related natural changes in concentrations and fluxes of these elements and Pb isotopic composition. Concentrations and fluxes of most of elements were observed to be highly variable with higher values during glacial maxima and lower values during warmer periods. Crustal enrichment factors suggest various sources for the different elements. The contribution from volcanic emissions appears to be very important for most of trace elements when climatic conditions become warmer. Pb isotopic compositions also show variations with changing climate due to relative proportions of dust and volcanic Pb. The results demonstrate that a natural variability of elemental and Pb isotopic compositions are strongly linked to climatic conditions during interglacial periods before and after the Mid-Brunhes Event (~43 kyr BP). Finally, our data indicate that human activity has induced the greatest perturbation of the atmospheric cycles of these elements ever experienced over a period of ~800 kyr in the remotest area on Earth.