Biomarker concentrations in gravity core MSM45_19-2

• Main Authors: Kolling, Henriette Marie, Schneider, Ralph R, Stein, Ruediger, Fahl, Kirsten
• Format: Dataset
• Language: English
• Published: PANGAEA 2022
• Subjects: 2,6,10,14-Tetramethyl-7-(3-methylpent-4-enyl)pentadecane; per unit mass total organic carbon; 2,6,10,14-Tetramethyl-7-(3-methylpent-4-enyl)pentadecane per unit sediment mass; 24-Methylcholest-5-en-3beta-ol; 24-Methylcholest-5-en-3beta-ol per unit sediment mass; 24-Methylcholesta-5,22E-dien-3beta-ol; 24-Methylcholesta-5,22E-dien-3beta-ol per unit sediment mass; 4alpha,23,24-Trimethyl-5alpha-cholest-22E-en-3beta-ol; 4alpha,23,24-Trimethyl-5alpha-cholest-22E-en-3beta-ol per unit sediment mass; 8.2 ka event; Accumulation rate; 2,6,10,14-Tetramethyl-7-(3-methylpent-4-enyl)pentadecane per year; 24-Methylcholest-5-en-3beta-ol per year; 24-Methylcholesta-5,22E-dien-3beta-ol per year; 4alpha,23,24-Trimethyl-5alpha-cholest-22E-en-3beta-ol per year; highly branched isoprenoids (Z); triunsatured per year; Accumulation rate per year; Biomarker; brassica sterol; campesterol; DEPTH; sediment/rock; dionsterol; GC; Gravity corer; HBI III; triunsatured; triunsatured per unit sediment mass; Holocene; IP25; Labrador Sea; Labrador Shelf; Maria S. Merian; MSM45; MSM45_418-2; MSM45-19-2; primary production; Sea ice; Terrigenious input; Arctic; ice algae; Ice Sheet
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.949065; https://doi.org/10.1594/PANGAEA.949065

Sea ice and paleoenvironmental conditions were reconstructed based on gravity core MSM45_19-2 from the northern Labrador Shelf. Gravity core MSM45_19-2 was obtained during R/V Maria S. Merian expedition MSM45 (58°45.68'N, 61°56.25'W, water depth: 202 m) in 2015 (Schneider et al., 2016). For paleoenvironmental reconstructions of the last 9,000 years BP, biomarkers representing sea ice algae productivity (IP25), open-water phytoplankton productivity (brassicasterol, dinosterol and HBI III (Z)) and terrigenous input (campesterol) where analyzed. Aim of this study was to investigate (i) the role sea ice played before and during the final demise of the Laurentide Ice Sheet between 8.7 and 8.2 kyr BP, and (ii) the effects of meltwater events on remaining sea-ice cover and primary productivity. Concentrations of specific biomarkers were analyzed. 4-5 g of each sediment sample were extracted by sonication (3 x 15 min) using dichloromethane:methanol (2:1 v/v; 30 ml) as solvent. Prior to biomarker extraction two internal standards 7-HND (7-hexylnonadecane, 20 μl/sample) and androstanol (5α-androstan-3β-ol, 20 μl/sample) were added for quantification purposes. Hydrocarbon and sterol fractions were separated by open-column chromatography with SiO2 as stationary phase. For hydrocarbons, n-hexane (5 ml) and for sterols, ethylacetate:n-hexane (2:8 v/v; 7 ml) were used as eluent. Sterol fractions were silylated using 200 μl BSTFA (2 h, 60°C). Hydrocarbon concentrations were determined with a gas chromatograph coupled to an mass selective detector. For detailed measurement settings and compound identification see Fahl and Stein (2012). All biomarker concentrations were normalized to both the extracted weight of sediment (μg/gSed) and TOC (μg/gTOC). Further, accumulation rates were calculated (μg/cm2/yr) after the following equation (e.g., Stein & Macdonal, 2004): MAR = SR x DBD (1) TOC AR = MAR x TOC/100 (2) BM AR = MAR x BM (3) with MAR = Marine Accumulation Rate, SR = sedimentation rate (cm/yr), DBD = dry buld density ...