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


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 authentic external standards. Concentrations of all reported lipid biomarkers were normalized to the TOC content of the respective sediment samples (µg/g TOC) and are given as fractional abundances for each compound class.Sediment and plant samples for Radiocarbon (14C) analysis were pre-treated and analyzed as described by Rethemeyer et al. (2019). For the analysis of 14C in bulk organic carbon (bulk OC) and plant fossils were washed with 1% HCl (1 hr, 60°C followed by ca. 10 hr at room temperature) to remove carbonates. The acid insoluble fraction was then graphitized and analyzed for 14C at the CologneAMS facility (Cologne, Germany).For compound-specific 14C analysis individual alkanoic acids, alkanes and alkanols were isolated by preparative capillary GC using a gas chromatograph (7680 Agilent Technologies, USA) equipped with a CIS 4 injection system (Gerstel, Germany), coupled with a preparative fraction collector (PFC; Gerstel, Germany). The purity and quantity of individual compounds was monitored by GC-FID (Agilent 7890B equipped with an on-column injector, Agilent Technologies, USA). Samples with a purity of >98% were processed further. For samples from core Co1305 compound-specific 14C analysis was performed on a MICADAS AMS system equipped with a gas ionization source (ETH Zurich, Switzerland, Wacker et al., 2010) on purified CO2 produced by combustion in vacuum-sealed quartz tubes. Compound ages were corrected for processing blanks and carbon added during derivatization using mass balance (Berg et al., 2020). For core Co1308 compound-specific 14C analysis was conducted on the original isolated compounds with a High Voltage 6 MV Tandetron coupled to an EA-GIS periphery at the CologneAMS facility (Stolz et al., 2019).Compound-specific F14C values were corrected for processing blanks and the addition of one carbon atom during derivatization using mass balance (Berg et al. 2020 and Scheidt et al., 2021). AMS results are reported as fraction modern (F14C) and conventional radiocarbon ages (yrs BP) as outlined in Stuiver & Polach (1977)

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Metadata Access
Creator Berg, Sonja ORCID logo; Kusch, Stephanie ORCID logo; Jivcov, Sandra ORCID logo
Publisher PANGAEA
Publication Year 2024
Funding Reference German Research Foundation Crossref Funder ID 463250038 Integrating terrestrial and marine sediment records from East Antarctica to explore late Pleistocene and Holocene ice sheet instability; German Research Foundation Crossref Funder ID 5472008 Priority Programme 1158 Antarctic Research with Comparable Investigations in Arctic Sea Ice Areas
Rights Creative Commons Attribution 4.0 International; Data access is restricted (moratorium, sensitive data, license constraints);
OpenAccess false
Resource Type Bundled Publication of Datasets; Collection
Format application/zip
Size 5 datasets
Discipline Earth System Research
Spatial Coverage (-36.593W, -54.215S, -36.538E, -54.187N)
Temporal Coverage Begin 2013-04-01T00:00:00Z
Temporal Coverage End 2013-04-11T00:00:00Z