A NEW SAMPLE PREPARATION SYSTEM FOR MICRO-14C DATING OF GLACIER ICE WITH A FIRST APPLICATION TO A HIGH ALPINE ICE CORE FROM COLLE GNIFETTI (SWITZERLAND)
A NEW SAMPLE PREPARATION SYSTEM FOR MICRO-14C DATING OF GLACIER ICE WITH A FIRST APPLICATION TO A HIGH ALPINE ICE CORE FROM COLLE GNIFETTI (SWITZERLAND)
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DOI：
10.1017/rdc.2017.99
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发表时间：
2018-04-01
期刊：
影响因子：
8.3
通讯作者：
Wagenbach, Dietmar
中科院分区：
文献类型：
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作者：
Hoffmann, Helene;Preunkert, Susanne;Wagenbach, Dietmar
冰川冰的放射性测年是地层测年方法无法应用的重要工具。这项研究的重点是阿尔卑斯山冰川冰，并提出了一个新的样品制备系统，通过放射性碳（C-14）测年的微观颗粒有机碳（POC）部分纳入冰基质的冰川冰样品。开发了一种适应性强、成本低的在线过滤-氧化单元（REFILOX），首次将从冰过滤到CO2定量的所有样品制备步骤统一在一个封闭的装置中。对现代欧洲气溶胶样品进行的一项系统的C-14调查显示，340摄氏度的POC燃烧温度提供了真实的样品年龄的最佳代表。最大0.3 +/- 0.1 μ gC的非常低的过程空白现在能够在300-500 g的冰样品质量范围内对高阿尔卑斯冰样品进行C-14测年，其中POC浓度通常较低（通常为10-50 μ gC/kg）。在第一次成功的应用中，该方法被用来获得冰芯的年龄限制从寒冷的，高阿尔卑斯山积雪鞍Colle Gnifetti（瑞士）。底部冰芯部分的分析显示，4171-3923 cal yr BP的基础年龄，但也是迄今为止的年龄-深度关系的谜一样的不连续性。
Radiometric dating of glacier ice is an essential tool where stratigraphic dating methods cannot be applied. This study focuses on Alpine glacier ice and presents a new sample preparation system for dating of glacier ice samples via radiocarbon (C-14) dating of the microscopic particulate organic carbon (POC) fraction incorporated in the ice matrix. An adaptable, low-cost inline filtration-oxidation-unit (REFILOX) has been developed, which for the first time unifies all sample preparation steps from ice filtration to CO2 quantification in one closed setup. A systematic C-14 investigation of modern European aerosol samples revealed that a POC combustion temperature of 340 degrees C provides the best representation of the real sample age. A very low process blank of maximally 0.3 +/- 0.1 mu gC now enables C-14 dating of high Alpine ice samples, where POC concentrations are generally low (typically 10-50 mu gC/kg), in an ice sample mass range of 300-500 g. In a first successful application, the method was used to obtain age constraints for an ice core from the cold, high Alpine firn saddle Colle Gnifetti (Switzerland). Analysis of the bottom ice core sections revealed a basal age of 4171-3923 cal yr BP but also a so far enigmatic discontinuity in the age-depth relationship.