In Antarctic and Subantarctic environments, ¹⁴C‐based age determination is often challenging due to unknown reservoir effects, low organic carbon contents of sediments, and high contributions of petrogenic (¹⁴C‐free) carbon in ice marginal settings. In this study, we evaluate possible benefits and challenges of compound‐specific radiocarbon analysis (CSRA) as a tool for age determination of marine Antarctic and Subantarctic sediment sequences. We present a comprehensive data set of ¹⁴C ages obtained on bulk organic carbon, carbonates, and on fatty acids (FA) from three coastal marine sediment cores from Subantarctic South Georgia and East Antarctica. Low molecular weight (LMW) FA represent the least ¹⁴C‐depleted fraction, indicating that the phytoplankton‐derived compounds can be a means of dating sediments. In contrast, vascular plant‐derived high molecular weight FA are systematically depleted in ¹⁴C relative to the low molecular weight homologues, reflecting processes such as soil formation/erosion in the catchment. Comparative age‐depth models show significant differences, depending on the material used for the respective models. While the land plant‐derived FA may lead to an overestimation of the actual sediment age, LMW FA reveal complex aquatic reservoir effects. Bulk sedimentary organic carbon ¹⁴C ages likely provide appropriate age estimates in settings with low petrogenic carbon input in the Antarctic, whereas CSRA has the potential to produce improved age control in settings with high contributions of petrogenic carbon.

中文翻译：

---

（亚）南极沿海海洋沉积物的复合物特定放射性碳分析-年代学的潜力和挑战

在南极和亚南极环境中，由于储层效应未知，沉积物中有机碳含量低以及冰缘环境中的成岩（无¹⁴ C）碳贡献很大，基于¹⁴ C的年龄确定常常具有挑战性。在这项研究中，我们评估了化合物特异性放射性碳分析（CSRA）作为确定海洋南极和亚南极沉积序列年龄的工具可能带来的好处和挑战。我们提供了^14个C年龄的综合数据集，这些数据分别来自亚南极南乔治亚州和南极东部的三个沿海海洋沉积物核中的大量有机碳，碳酸盐和脂肪酸（FA）。低分子量（LMW）FA代表最少¹⁴C含量减少的部分，表明浮游植物衍生的化合物可以作为对沉积物定年的一种手段。相比之下，相对于低分子量同系物，维管束来源的高分子量FA在¹⁴ C时系统地消耗，反映了集水区土壤形成/侵蚀等过程。比较年龄深度模型显示出明显的差异，具体取决于各个模型所使用的材料。尽管源自陆地植物的FA可能导致高估了实际的沉积年龄，但LMW FA揭示了复杂的水库影响。大量沉积有机碳¹⁴在南极生油碳输入量低的环境中，C年龄可能提供适当的年龄估计，而CSRA有可能在高成岩碳作用的环境中改善年龄控制。