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

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（n-alkanes）的浓度数据。正构烷烃浓度（单位：微克/克，ug/g）、碳优势指数（Carbon Preference Index, CPI）以及平均链长C21-C33（Average Chain Length C21-C33, ACL）均随深度（米）和年代（校准年距今，cal yr BP）给出。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则用于估算有机质的来源与保存状况。本研究共对该岩心晚冰期层位的167个样品进行了前处理，采用戴安（Dionex）350加速溶剂萃取（accelerated solvent extraction, ASE）系统完成萃取。固相萃取（Solid Phase Extraction, SPE）被用于将萃取物分离为脂肪族、芳香族及醇/脂肪酸三个组分。具体分离流程为：将萃取物上样至活化硅胶柱，依次以正己烷、正己烷/二氯甲烷（体积比1:1，v/v）以及二氯甲烷/甲醇（体积比9:1，v/v）进行洗脱，完成各组分分离。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-雄甾烷，5α-androstane）及外标正构烷烃混合标准品的峰面积进行比对，以此实现绝对定量。详细的分析实验细节可参考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。