DO RADIOCARBON AGES OF PLANT WAX BIOMARKERS AGREE WITH 14C-TOC/OSL-BASED AGE MODELS IN AN ARID HIGH-ALTITUDE LAKE SYSTEM?
DO RADIOCARBON AGES OF PLANT WAX BIOMARKERS AGREE WITH 14C-TOC/OSL-BASED AGE MODELS IN AN ARID HIGH-ALTITUDE LAKE SYSTEM?
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DOI：
10.1017/rdc.2021.78
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发表时间：
2021-09
期刊：
影响因子：
8.3
通讯作者：
Bernhard Aichner;M. Gierga;Alexander Stolz;Monika Mętrak;Mateusz Wilk;M. Suska-Malawska;S. Mischke;D. Sachse;I. Rajabov;Nasimjon Rajabov;J. Rethemeyer
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文献类型：
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作者：
Bernhard Aichner;M. Gierga;Alexander Stolz;Monika Mętrak;Mateusz Wilk;M. Suska-Malawska;S. Mischke;D. Sachse;I. Rajabov;Nasimjon Rajabov;J. Rethemeyer
为了阐明高海拔湖泊系统中陆地叶蜡的动态变化，我们对塔吉克斯坦帕米尔帕米尔高原卡拉库尔湖两个沉积物岩心和集水区表层土壤样品中的长链正构烷烃进行了化合物特异性放射性碳分析(CSRA)。我们的目的是回答这样一个问题，即正构烷烃是否由于储存在土壤中而被大量延迟地输送到湖泊沉积物中，这可能会导致潜在的偏差，当用作古环境代用品时。在表层土壤中，CSRA结果显示正构烷烃的年龄范围从现代到2278±155calBP。在两个沉积物岩心样品中，四个正构烷烃年龄中的三个落在沉积物模拟年龄的1σ不确定范围的较低端(基于AMS14C-TOC和OSL测年结果)。我们的结论是，沉积叶蜡代表土壤中具有中间周转时间的化合物，例如来自海岸附近冲积平原的化合物。总体而言，这些结果提供了证据，表明在这种寒冷和干旱的环境中，沉积的叶蜡化合物可能比传统的年龄模型所显示的年代更早，但这些发现需要在这种年龄模型普遍存在较大不确定性范围的背景下进行解释。
ABSTRACT To elucidate the dynamics of terrestrial leaf waxes in a high-altitude lake system, we performed compound-specific radiocarbon analysis (CSRA) of long-chain n-alkanes in two sediment core sections from Lake Karakul (Pamirs, Tajikistan) and in surface soil samples from the catchment area. We aimed to answer the question whether the n-alkanes are delivered into the lake sediment with substantial delay due to storage in soils, which may cause a potential bias when used as paleoenvironmental proxies. In the surface soils, the CSRA results reveal an age range of n-alkanes from modern to 2278 ± 155 cal BP. In the two sediment core samples, three of the four n-alkane ages fell on the lower ends of the 1σ-uncertainty ranges of modeled ages of the sediments (based on AMS 14C-TOC and OSL dating results). We conclude that sedimentary leaf waxes represent compounds with intermediate turnover time in soils, for example originating from alluvial plains close to the shores. Overall, the results provide evidence that sedimentary leaf wax compounds in this cold and arid setting are potentially older than the conventional age model indicates, but these findings need to be interpreted in context of the generally large uncertainty ranges of such age models.