Stable Isotope Studies at East Antarctic US ITASE Sites

This award supports a project to obtain stable isotope profiles from shallow (<100 m) ice cores from East Antarctica, to add to the growing database of environmental proxy data collected under the auspices of the \"ITASE\" (International TransAntarctic Scientific Expedition) program. In Antarctica, the instrumental record of climate is particularly short (~40 years except in a few isolated locations on the coast), and ice core proxy data are the only means available for extending this record into the past. The use of stable isotopes of water (18-O/16-O and D/H ratios) from ice cores as proxies for temperature is well established for both very short (i.e. seasonal) and long timescales (centuries, millennia). Using multivariate regression methods and shallow ice cores from West Antarctica, a reconstruction of Antarctic climate over the last ~150 years has been developed which suggests the continent has been warming, on average, at a rate of ~0.2 K/century. Further improving these reconstructions is the chief motivation for further extending the US ITASE project. Ten to fifteen shallow (~100 m) from Victoria Land, East Antarctica will be obtained and analyzed. The core will be collected along a traverse route beginning at Taylor Dome and ending at the South Pole. Age-depth relationships for the cores will be determined through a combination of stable isotopes, visual stratigraphy and seasonal chemical signatures and marker horizons. Reconstructions of Antarctic climate obtained from these cores will be incorporated into the global network of paleoclimate information, which has been important in science, policy and educational contexts. The project will include graduate student and postdoctoral training and field experience.

本奖项资助的项目将从南极东部深度小于100米的浅冰芯中获取稳定同位素剖面，以扩充由国际跨南极科学考察（International TransAntarctic Scientific Expedition，ITASE）计划主导构建的环境代用数据数据库。在南极地区，仪器观测的气候记录时长极短（除沿海少数孤立点位外仅约40年），而冰芯代用数据是将此类记录延伸至史前的唯一可行手段。利用冰芯中水体的稳定同位素（¹⁸O/¹⁶O及D/H比值）作为温度代用指标的方法，在短至季节尺度、长至世纪乃至千年尺度上均已得到充分验证。此前研究借助多元回归方法与西南极浅冰芯，重建了过去约150年的南极气候，结果显示该大陆平均升温速率约为0.2开尔文每世纪。进一步完善此类气候重建工作，正是本次美国ITASE计划拓展项目的核心动机。本次项目将从南极东部维多利亚地采集10至15根深度约100米的浅冰芯并开展分析。冰芯的采集将沿从泰勒穹顶（Taylor Dome）至南极点的考察路线进行。冰芯的年龄-深度关系将通过结合稳定同位素、视觉地层学、季节性化学特征与标志性层位予以确定。从这些冰芯中获取的南极气候重建数据，将被纳入全球古气候信息网络，而该网络在科学研究、政策制定与科普教育领域均发挥了重要作用。本项目还将包含研究生与博士后的培训及野外实践经历。