EAPSI: Using geochemistry to unravel the history of an East Antarctic ice shelf system

南极洲和南大洋在地球气候中扮演着中心角色。为了改进预测冰量和海平面变化的气候模型，了解影响南极冰块平衡的因素是很重要的。南极东部三个沉积物岩芯的地球化学特征可能揭示了南极冰盖在过去是如何波动的。这项研究将由东京大学的横山由介博士负责监督。必要的仪器和设施，以及横山博士在地球化学方面的专业知识，使这里成为一个理想的研究机会地点。南极冰块的减少往往与大陆架上温暖的海洋水域的存在同时发生，这表明冰架系统对海洋温度很敏感。确定冰架对海洋热量的敏感性对于理解冰盖的稳定性至关重要。在南极东部普里兹湾采集的第四纪晚期(125ka至今)海洋沉积物保存了冰架波动的证据。来自普里兹湾的三个岩芯显示，至少有四个硅质泥浆和软泥单元与冰川海洋单元互层，分别代表开阔海洋条件(无冰)和冰川条件(冰盖)。开阔的海洋和冰川交替的条件表明，普里兹湾的阿莫里冰架系统(AIS)随着时间的推移而波动。这项研究将通过测量普里兹湾三个沉积物岩芯中的同位素铍10(10Be)的相对丰度来检验这种变化。10Be的相对丰度是对沉积环境的间接测量；10Be丰度越高，表明远洋环境。建立普里兹湾的沉积环境对于生成更可靠的晚第四纪AIS历史至关重要。揭示南极东部最大出口冰川的历史与人们的担忧有关，即气候变化正在破坏南极冰盖的稳定，并对未来海平面上升产生影响。该NSF EAPSI奖是与日本科学促进会合作资助的。

Antarctica and the Southern Ocean play a central role in Earth's climate. To improve the climate models that predict changes in ice volume and sea level, it is important to understand factors affecting Antarctic ice mass balance. The geochemistry of three East Antarctic sediment cores may reveal how Antarctica's ice sheets fluctuated in the past. This research will be supervised by Dr. Yusuke Yokoyama, at the University of Tokyo. Necessary instruments and facilities, as well as Dr. Yokoyama's expertise in geochemistry make this an ideal research opportunity site.Reductions in Antarctic ice mass often co-occur with the presence of warm oceanic waters on the continental shelf, suggesting that ice shelf systems are sensitive to ocean temperatures. Identifying the sensitivity of ice shelves to ocean heat is critical for understanding ice sheet stability. Late Quaternary (125 ka-present) marine sediments collected in Prydz Bay, East Antarctica preserve evidence of ice shelf fluctuations. Three cores from Prydz Bay reveal at least four siliceous mud and ooze units interbedded with glacial marine units, representing open-marine conditions (ice-free) and glacial conditions (ice-covered), respectively. Alternating open-marine and glacial conditions suggest the Amery Ice Shelf system (AIS) in Prydz Bay has fluctuated through time. This research will examine this variation by measuring the relative abundance the isotope, beryllium 10 (10Be) in three Prydz Bay sediment cores. Relative abundance of 10Be is an indirect measurement of depositional environment; a higher abundance of 10Be indicates open-marine conditions. Establishing the depositional environment in Prydz Bay is essential to generating a more reliable late Quaternary AIS history. Unveiling the history of the largest outlet glacier in East Antarctica is relevant to concerns that climate change is destabilizing Antarctic ice sheets, with implications for future sea level rise. This NSF EAPSI award is funded in collaboration with the Japan Society for the Promotion of Science.