Dry mass concentrations of individual n-alkanes in sediment core Haem13 from lake Hämelsee@en

This dataset provides concentrations of n-alkanes for the Lateglacial sediment sequence retrieved from Lake Hämelsee (Germany) in 2013. Concentrations of n-alkanes (ug/g), the Carbon Preference Index (CPI) and the Average Chain Length C21-C33 (ACL) are all presented against both depth (m) and age (cal yr. BP). The n-alkane concentration data provides information on the Lateglacial dynamics of local plant productivity, whereas the ACL and CPI of the sediment samples were determined to estimate origin and preservation condition. A total of 167 samples from the Lateglacial section of the core were processed using a Dionex 350 accelerated solvent extraction (ASE) system. Solid phase extraction (SPE) was used to separate the extracts into an aliphatic, aromatic and alcohol/fatty acid fraction. Separation was achieved by loading the extracts on activated silica columns and eluting each fraction with hexane, hexane/DCM (1:1 v/v) and DCM/MeOH (9:1 v/v) successively. The aliphatic fraction, containing the n-alkanes, was analyzed by gas chromatography-mass spectrometry (GC/MS). The peak areas for each n-alkane homologue were compared to the peak areas from an internal standard (5α-androstane) and an external n-alkane standard mixture for absolute quantification. We refer to Rach et al. (2020) for further details on the exact analytical setup. All measurements were performed in the laboratories of GeoForschungsZentrum Potsdam.本数据集提供了2013年从德国黑梅尔湖（Lake Hämelsee）获取的晚冰期沉积序列中正构烷烃的浓度数据。正构烷烃浓度（单位：μg/g）、碳偏好指数（CPI）以及C21-C33平均链长（ACL）均以深度（m）和年龄（cal yr BP，校正年距今）为参照列出。正构烷烃浓度数据可用于揭示区域植物生产力的晚冰期动态变化，而沉积样品的ACL与CPI则可用于估算有机质的来源与保存状况。本岩心晚冰期层位共计167个样品，采用戴尼康（Dionex）350型加速溶剂萃取（accelerated solvent extraction, ASE）系统完成前处理。通过固相萃取（solid phase extraction, SPE）将提取物分离为脂肪族、芳香族以及醇/脂肪酸组分：将提取物上样至活化硅胶柱，依次以正己烷、正己烷/二氯甲烷（1:1 v/v）、二氯甲烷/甲醇（9:1 v/v）洗脱各组分。包含正构烷烃的脂肪族组分通过气相色谱-质谱联用仪（gas chromatography-mass spectrometry, GC/MS）进行分析。将每种正构烷烃同系物的峰面积与内标（5α-雄烷，5α-androstane）及外标正构烷烃混合标准品的峰面积进行比对，以实现绝对定量。关于具体分析流程的更多细节，可参考Rach等人（2020）的研究成果。所有测试工作均在波茨坦地学研究中心（GeoForschungsZentrum Potsdam）的实验室完成。