East Antarctic ice core sulfur isotope measurements over a complete glacial‐interglacial cycle

Abstract

Both sulfur and oxygen isotopes of sulfate preserved in ice cores from Greenland and Antarctica have provided information on the relative sources of sulfate in the ice and their chemical transformation pathways in the atmosphere over various time periods. The mass‐independent fractionation in the oxygen isotopes of sulfate from the Vostok ice core from east Antarctica suggests that gas‐phase oxidation by the hydroxyl radical (OH) was relatively greater than aqueous‐phase oxidation by O3 and H2O2 during the last glacial period than during the Eemian and preindustrial Holocene. The complete sulfur isotopic composition (δ33S, δ34S, δ36S) from the same Vostok ice core samples along with δ34S measurements from the Dome C, east Antarctic ice core from this study lend support to these conclusions and reveal significant isotopic fractionation of δ34S during chemical transformation and transport to east Antarctica. These findings reveal that conservation of sulfur isotopic signatures upon transport cannot be assumed for the East Antarctic plateau over the time periods considered.