To achieve high-precision and reproducible results from radiocarbon (14C) dating of carbonate samples in paleoclimate research, a new CO2 extraction line was designed, constructed, and characterized at the Heidelberg Radiocarbon Lab of the Institute of Environmental Physics, Heidelberg. The setup includes a circular glass-tube design, which is operated at vacuum pressure levels of the order of 10–5 mbar. The efficiency of the extraction process was assessed, showing significantly favorable conditions for solid piece samples (99.58 ± 4.69)% over powdered samples (88.28 ± 10.03)%. Process blank values are below 0.2 pMC apparent 14C activity. Repeated measurements of IAEA C2 standards with an average value of (41.09 ± 0.23) pMC attest high accuracy and reproducibility of the instrument. Six consecutive samples of 6 to 12 mg carbonate mass can be processed in one run of roughly 2.5 hours. Thus, the new setup contributes to time-efficient and reproducible radiocarbon dating results for paleoclimate research at the Institute of Environmental Physics. In a first application, Dead Carbon Fraction (DCF) values of a Holocene alpine stalagmite from Schratten Cave are presented, revealing extraordinarily high offsets between atmospheric and stalagmite 14C with DCF values between (49.4 ± 0.4)% and (61.6 ± 0.4)%.

中文翻译：

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海德堡放射性碳实验室——建立新的碳酸盐样品二氧化碳提取线

从放射性碳中获得高精度和可重复的结果（14C) 古气候研究中碳酸盐样品的年代测定，一种新的 CO2提取线是在海德堡环境物理研究所的海德堡放射性碳实验室设计、建造和表征的。该装置包括一个圆形玻璃管设计，可在 10 级的真空压力水平下运行–5毫巴。对提取过程的效率进行了评估，结果表明固体样品 (99.58 ± 4.69)% 优于粉末样品 (88.28 ± 10.03)% 的条件明显有利。工艺空白值明显低于 0.2 pMC14C 活动。IAEA C2 标准的重复测量平均值为 (41.09 ± 0.23) pMC，证明了仪器的高精度和可重复性。在大约 2.5 小时的一次运行中可以处理 6 到 12 毫克碳酸盐质量的六个连续样品。因此，新设置有助于为环境物理研究所的古气候研究提供时间高效且可重复的放射性碳测年结果。在第一个应用程序中，展示了来自 Schratten 洞穴的全新世高山石笋的死碳分数 (DCF) 值，揭示了大气和石笋之间非常高的偏移量14C，DCF 值介于 (49.4 ± 0.4)% 和 (61.6 ± 0.4)% 之间。