Alkyl lipid distribution, elemental composition and compound-specific 14C isotope composition in marine and terrestrial sedimentary archives from sub-Antarctic South Georgia

• Main Authors: Berg, Sonja, Kusch, Stephanie, Jivcov, Sandra
• Format: Other/Unknown Material
• Language: English
• Published: PANGAEA 2024
• Subjects: alkanes; alkanoic acids; alkanols; alkyl lipids; compound-specific radiocarbon analysis; Priority Programme 1158 Antarctic Research with Comparable Investigations in Arctic Sea Ice Areas; sediments; South Georgia; SPP1158; Antarc*; Antarctic; Sea ice
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.967394; https://doi.org/10.1594/PANGAEA.967394

The dataset comprises elemental data, alkyl lipid data and radiocarbon (14C) data that was obtained on sediment samples from sub-Antarctic South Georgia. The sediments were collected from a range of different sites, including lakes, peat deposits, a marine inlet and a fjord during RV Polarstern expedition PS81 in 2013. Prior to the geochemical analyses reported here, the sediments were freeze-dried and ground. More details on the study sites, sampling and data evaluation can be found in Berg et al. (submitted manuscript). Total organic carbon (TOC) was analyzed with a DIMATOC 200 (DIMATEC Corp., Canada) analyser. The TOC concentration is derived from the difference between total carbon (TC) and total inorganic carbon (TIC) Total carbon (C), total nitrogen (N) and sulfur (S) were analyzed using a Vario Micro Cube combustion elemental analyser (Elementar, Germany). Alkyl lipid biomarkers were extracted by accelerated solvent extraction (ASE 300, Thermo, USA) with dichloromethane and methanol (DCM, MeOH; 9:1, v/v at 120°C, 75 bar) (cores Co1305, PS81/283, and Co1308) or via consecutive ultrasonication in DCM:Hexan (1:1), MeOH:DCM (1:1) and MeOH (core Co1306 and the peat and soil samples). The total lipid extract (TLE) was saponified with 0.5 M KOH in MeOH and water (9:1, v/v) at 80°C for 2 h. Neutral lipids (NL) were extracted from the TLE with dichloromethane by liquid-liquid phase separation. Alkanes were purified from NL by silica gel column chromatography (SiO2, deactivated, mesh-size 60) by elution with hexane and alkanols by elution with chloroform. To purify alkanoic acids, the remaining TLE was acidified to pH 1 and acids were extracted from the TLE with dichloromethane by liquid-liquid phase separation. Prior to analysis by gas chromatography (GC, Agilent 7890B, Agilent Technologies, USA) equipped with a flame ionization detector (FID), alkanols were acetylated and alkanoic acids were converted to methyl ester derivatives. Alkanes, alkanols and alkanoic acids were identified and quantified against ...