Berg, Sonja; Kusch, Stephanie; Jivcov, Sandra (2024): Alkyl lipid distribution, elemental composition and compound-specific 14C isotope composition in marine and terrestrial sedimentary archives from sub-Antarctic South Georgia [dataset bundled publication]. PANGAEA, https://doi.org/10.1594/PANGAEA.967394
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Abstract:
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)
Keyword(s):
Related to:
Berg, Sonja; et al. (accepted): Alkyl lipid distributions and compound-specific 14C isotope compositions in diverse sedimentary archives in sub-Antarctic South Georgia: Deconvolving (past and present) marine and terrestrial sources and revealing localized export dynamics in response to environmental change.
References:
Berg, Sonja; Jivcov, Sandra; Kusch, Stephanie; Kuhn, Gerhard; Wacker, Lukas; Rethemeyer, Janet (2020): Compound‐specific radiocarbon analysis of (Sub‐)Antarctic coastal marine sediments ‐ potential and challenges for chronologies. Paleoceanography and Paleoclimatology, accepted, https://doi.org/10.1029/2020PA003890
Rethemeyer, Janet; Gierga, M; Heinze, S; Stolz, Alexander; Wotte, A; Wischhöfer, P; Berg, Sonja; Melchert, J O; Dewald, A (2019): Current Sample Preparation and Analytical Capabilities of the Radiocarbon Laboratory at CologneAMS. Radiocarbon, 61(5), 1449-1460, https://doi.org/10.1017/RDC.2019.16
Scheidt, Stephanie; Berg, Sonja; Hambach, Ulrich; Klasen, Nicole; Pötter, Stephan; Stolz, Alexander; Veres, Daniel; Zeeden, Christian; Brill, Dominik; Brückner, Helmut; Kusch, Stephanie; Laag, Christian; Lehmkuhl, Frank; Melles, Martin; Monnens, Florian; Oppermann, Lukas; Rethemeyer, Janet; Nett, Janina J (2021): Chronological Assessment of the Balta Alba Kurgan Loess-Paleosol Section (Romania) – A Comparative Study on Different Dating Methods for a Robust and Precise Age Model. Frontiers in Earth Science, 8, 598448, https://doi.org/10.3389/feart.2020.598448
Stolz, Alexander; Dewald, A; Heinze, S; Altenkirch, R; Hackenberg, G; Herb, S; Müller-Gatermann, C; Schiffer, M; Zitzer, G; Wotte, A; Rethemeyer, Janet; Dunai, Tibor J (2019): Improvements in the measurement of small 14CO2 samples at CologneAMS. Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions with Materials and Atoms, 439, 70-75, https://doi.org/10.1016/j.nimb.2018.12.008
Stuiver, Minze; Polach, Henry A (1977): Discussion: Reporting of 14C Data. Radiocarbon, 19(3), 355-363, https://doi.org/10.1017/S0033822200003672
Project(s):
Funding:
German Research Foundation (DFG), grant/award no. 463250038: Integrating terrestrial and marine sediment records from East Antarctica to explore late Pleistocene and Holocene ice sheet instability
German Research Foundation (DFG), grant/award no. 5472008: Priority Programme 1158 Antarctic Research with Comparable Investigations in Arctic Sea Ice Areas
Coverage:
Median Latitude: -54.200187 * Median Longitude: -36.565940 * South-bound Latitude: -54.215333 * West-bound Longitude: -36.592600 * North-bound Latitude: -54.187100 * East-bound Longitude: -36.538000
Date/Time Start: 2013-04-01T00:00:00 * Date/Time End: 2013-04-11T00:00:00
License:
Creative Commons Attribution 4.0 International (CC-BY-4.0) (License comes into effect after moratorium ends)
Size:
5 datasets
Download Data (login required; moratorium until 2025-09-30)
Datasets listed in this bundled publication
- Berg, S; Kusch, S; Jivcov, S (2024): Compound-specific 14C isotope composition in marine and terrestrial sedimentary archives from sub-Antarctic South Georgia. https://doi.pangaea.de/10.1594/PANGAEA.967398
- Berg, S; Kusch, S; Jivcov, S (2024): Elemental composition of marine and terrestrial sedimentary archives from sub-Antarctic South Georgia. https://doi.pangaea.de/10.1594/PANGAEA.967403
- Berg, S; Kusch, S; Jivcov, S (2024): N-alkane composition of marine and terrestrial sedimentary archives from sub-Antarctic South Georgia. https://doi.pangaea.de/10.1594/PANGAEA.967405
- Berg, S; Kusch, S; Jivcov, S (2024): Alkanol composition of marine and terrestrial sedimentary archives from sub-Antarctic South Georgia. https://doi.pangaea.de/10.1594/PANGAEA.967408
- Berg, S; Kusch, S; Jivcov, S (2024): Alkanoic acid composition of marine and terrestrial sedimentary archives from sub-Antarctic South Georgia. https://doi.pangaea.de/10.1594/PANGAEA.967441