Effects of handling, storage, and chemical treatments on δ13C values of terrestrial fossil organic matter
Effects of handling, storage, and chemical treatments on δ13C values of terrestrial fossil organic matter
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DOI：
10.1029/2008gc001967
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发表时间：
2008-08
期刊：
影响因子：
3.7
通讯作者：
C. Gauthier;C. Hatté
中科院分区：
文献类型：
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作者：
C. Gauthier;C. Hatté
随着对微量同位素变化解释的需要，沉积有机质δ 13 C分析在（古）气候学领域越来越广泛。最近的发展需要对整个数据采集链的可靠性和再现性进行评估。在物理测量之前对沉积物进行预处理的协议文献比比皆是。这些程序在每一步都不同：从取样、处理和储存条件到浸出程序，没有交叉评价。在这项研究中，我们专注于两个沉积物样品：现代温带土壤和70 ka的典型黄土。我们回顾不同的协议，表征沉积物预处理的每一步。测试处理和储存条件，例如，手指皮肤接触、中高温烘箱干燥和冷冻干燥。同样，比较了不同的脱碳酸方案：在冷的0.6 N HCl、2 N HCl和沸腾的1 N HCl下进行湿法脱碳酸，以及用36% HCl进行酸发烟。这项研究确定了高达1.5‰的同位素位移与实验偏倚有关。这种巨大的偏差可能是错误的古气候解释的起源。在这些结果的基础上，我们提出了适合于样品类型的具体处理方法。
With the need to interpret small isotopic variations, δ13C analyses of sedimentary organic matter are more and more widespread in the field of (paleo)climatology. Recent developments require an evaluation of the reliability and reproducibility of the whole data acquisition chain. Literature abounds in protocols for sediment pretreatment prior to physical measurements. These procedures differ at every step: from sampling, handling, and storage conditions to leaching procedure, without cross evaluation. In this study, we focus on two sediment samples: a modern temperate soil and a 70 ka typical loess. We review different protocols that characterize each step of the sediment pretreatment. Handling and storage conditions are tested, e.g., finger skin contact, mild‐ to high‐temperature oven‐dry, and freeze‐drying. Likewise, different decarbonation protocols are compared: wet decarbonation under cold 0.6 N HCl, 2 N HCl and boiling 1 N HCl, and acid fuming with 36% HCl. This study identifies up to 1.5‰ isotopic shifts linked to experimental bias. This large bias might be at the origin of erroneous paleoclimatic interpretation. On the basis of these results, we propose specific treatments adapted to the sample type.