Research Objectives:
This is a collaborative study to investigate the oxygen and sulfur isotope composition of sulfates from a number of large volcanic eruptions in the past 1,000 years. The project aims to drill a number of shallow ice cores at South Pole and return them to the principal investigators’ laboratories for chemical and isotope analysis. Preliminary results from measurements of isotopes in sulfate samples from several volcanic eruptions in Antarctic snow and ice indicate that isotopic composition of volcanic sulfate contains abundant valuable information on atmospheric chemical and dynamic processes that have not been previously investigated. One tentative conclusion is that mass-independently fractionated sulfur isotopes reveal that atmospheric photolysis of sulfur compounds occurs at longer UV wavelengths than those in the Archean atmosphere, possibly reflecting the atmospheric ozone and/or oxygen concentration. This suggests that isotopic composition of atmospheric sulfate may be used to understand the role of UV radiation in sulfur dioxide conversion in the atmosphere and to track the evolution (i.e., oxygenation) of the atmosphere and the origin of life on Earth.
Other major research objectives include understanding what impact massive volcanic eruptions have on the oxidative capacity of the atmosphere, what oxidants and mechanisms are involved in the oxidation or conversion of volcanic sulfur dioxide to sulfate in the stratosphere and what isotopic criteria may be used to differentiate ice core signals of stratospheric eruptions from those of tropospheric eruptions.
At the South Pole, project team members will drill several shallow ice cores and extract volcanic sulfate from them. They will analyze isotopes in extracted volcanic sulfate, and interpret isotope data in terms of atmospheric chemistry and dynamics. The science team will be assisted by a crew from ICDS (Ice Core Drilling Services) to drill and package about 400 meters of ice cores.
