Estimation of Antarctic Ice Melt using Stable Isotopic Analyses of Seawater

估计南极冰盖的增长或损失对预测未来海平面上升非常重要。这种估算依赖于对冰盖表面、冰缘和/或冰架的实地测量或基于遥感的观测。这项工作考察了淡水进入南极洲周围海洋的情况，以追踪大陆冰的融水。相对于南大洋的海水和降水，极地冰的两种稳定同位素（18O和D）氘的含量减少了。对海水同位素组成的测量结合对海水温度和盐度的精确观测，将能够区分冰川融化产生的淡水与区域降水或海冰融化产生的淡水。这项研究描述了一种公认的方法，用于确定从极地冰盖进入海洋的融水的速率和位置。由于在许多南极沿海海域中，同位素和盐度的扰动是累积的，因此该方法可以利用在数年至数十年期间收集和分析的样本，探测到特定区域融水引入的任何明显加速。该项目的影响来自于使用了一种独立的方法，能够限制有关当前冰盖融化速度、其稳定性和对海平面上升的潜在影响的知识。该项目允许从在南极水域航行的外国机遇船只上采集样本，并随后分享和解释数据。研究合作伙伴包括美国、韩国、中国、新西兰、英国和德国。参与的合作者将在斯坦福大学收集海水样本进行同位素和盐度分析。USAP的巡航将集中在罗斯海和南极西部取样。工作计划包括使用盒模型和混合曲线分析以及使用同位素支持的ROMS（区域海洋模拟系统）模型来解释同位素数据。这项研究的更广泛影响将包括开发一个教育模块，说明科学方法和海洋观测如何帮助社会了解地球是如何变化的。

Estimating Antarctic ice sheet growth or loss is important to predicting future sea level rise. Such estimates rely on field measurements or remotely sensed based observations of the ice sheet surface, ice margins, and or ice shelves. This work examines the introduction of freshwater into the ocean to surrounding Antarctica to track meltwater from continental ice. Polar ice is depleted in two stable isotopes, 18O and D, deuterium, relative to Southern Ocean seawater and precipitation. Measurements of seawater isotopic composition in conjunction with precise observations of seawater temperature and salinity, will permit discrimination of freshwater derived from melting glacial ice from that derived from regional precipitation or sea ice melt.This research describes an accepted method for determining rates and locations of meltwater entering the oceans from polar ice sheets. As isotopic and salinity perturbations are cumulative in many Antarctic coastal seas, the method allows for the detection of any marked acceleration in meltwater introduction in specific regions, using samples collected and analyzed over a period of years to decades. Impact of the project derives from use of an independent method capable of constraining knowledge about current ice sheet melt rates, their stability and potential impact on sea level rise. The project allows for sample collection taken from foreign vessels of opportunity sailing in Antarctic waters, and subsequent sharing and interpretation of data. Research partners include the U.S., Korea, China, New Zealand, the United Kingdom, and Germany. Participating collaborators will collect seawater samples for isotopic and salinity analysis at Stanford University. USAP cruises will concentrate on sampling the Ross Sea, and the West Antarctic. The work plan includes interpretation of isotopic data using box model and mixing curve analyses as well as using isotope enabled ROMS (Regional Ocean Modeling System) models. The broader impacts of the research will include development of an educational module that illustrates the scientific method and how ocean observations help society understand how Earth is changing.