A research group led by Assistant Professor Hiroshi Ohno of Kitami Institute of Technology, Assistant Professor Yoshinori Iizuka of Hokkaido University, and the National Institute of Polar Research conducted detailed physicochemical analysis of deep ice collected at Dome Fuji Station in the inland area of the Antarctic. We elucidated the physicochemical properties of the deepest part of the ice core, which is considered to be one of the oldest ice on the earth.
Research on "ice cores," which are ice samples made by hollowing out the Antarctic ice sheet into columns, is being actively conducted by Japan, the United States, and Europe in order to elucidate the history of past climate changes.The deepest part of the Dome Fuji ice core excavated at Dome Fuji base from 2003 to 2007 is expected to go back more than 70 years to understand the past global environment, and at the same time, the deepest part of the Antarctic ice sheet is cold. It is thought to be inhabited by unknown extremophiles that can withstand high-pressure environments.However, little is known about the origin and existence of ice near the bottom of the ice sheet in the interior of Antarctica.
The research group investigated in detail the physicochemical properties of ice cores recovered from the deepest part (3000-3035 m deep).To clarify the origin and history of deep ice, mainly for the concentration of ions contained in deep ice and shallow ice (0 to 13 years ago, about 0 to 1750 m deep) and the oxygen isotope ratio of water. We systematically acquired a wide range of information, such as component analysis, and comprehensively analyzed it to elucidate the environment at the deepest part of the ice sheet and the physicochemical processes that are occurring.
As a result of research, all deep ice originated from rainwater (snowfall) during the warm season, and significant redistribution of chemical components occurred near the bottom of the ice sheet. It was found that crystals formed by the reaction of water at low temperature and high pressure) are caused by segregation on the grain surface and ice crystal grain boundaries, and transfer along the grain boundaries.
In the future, if we find old ice that is placed in a relatively low temperature environment, it will be possible to extract well-preserved paleoenvironment information based on the results of this research.In addition, it is expected that discussions on ice sheet microbiology will proceed based on the new findings on the physicochemical structure of ice that have been revealed this time.
