First results from stable-istope measurements on ice cores from Dronning Maud Land

The European Project for Ice Coring in Antarctica (EPICA) focuses on the drilling of two deep ice cores, the first at Dome C and the second at Kohnen station (75°00' S, 0°04' E) in Dronning Maud Land (DML). This paper deals with stable-isotope records from ice cores drilled in DML. In the first season, the deep EPICA DML core reached a depth of 450 m, recovering ice approximately 7000 years old. Generally, the d18O record indicates a stable Holocene climate and shows low variability. However, during the last 4000 years (based on a preliminary time-scale) the d18O values decrease continuously by about 0.6%, and the deuterium excess values increase by about 0.5%. The correlation between d18O and the deuterium excess d is investigated for a 50m long core section and the near-surface snow. High-pass filtered profiles are positively correlated, whereas the correlation between low-pass filtered profiles is negative. A post-depositional effect due to diffusion processes can be seen in a sub-annually resolved profile from snow-pit samples. Changes in the seasonality of the evolution of the snow cover and the consequences for stable-isotope content are demonstrated with data from ice core B31.

欧洲南极冰芯钻探项目（EPICA）致力于钻探两根深冰芯，第一根位于C冰穹，第二根位于多宁·莫德地（DML）的科嫩站（南纬75°00′，东经0°04′）。本文研究了在DML钻探的冰芯中的稳定同位素记录。在首个钻探季，EPICA DML深冰芯达到450米深度，获取了约7000年前的冰样。总体而言，δ¹⁸O记录显示全新世气候稳定且变率较低。然而，基于初步时间尺度，过去4000年中δ¹⁸O值持续下降约0.6%，氘过量值则上升约0.5%。针对一段50米长的冰芯剖面和近地表积雪，研究人员分析了δ¹⁸O与氘过量值d之间的相关性：高通滤波后的剖面呈正相关，而低通滤波后的剖面呈负相关。在雪坑样本的亚年度分辨率剖面中，可观察到扩散过程导致的沉积后效应。利用B31冰芯的数据，本文展示了积雪演化的季节性变化及其对稳定同位素含量的影响。