Biomarker concentrations in gravity core MSM45_19-2
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| Format: | Dataset Open Access |
| Langue: | en |
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PANGAEA
2022
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| _version_ | 1867170115466821632 |
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| author | Kolling, Henriette Marie Schneider, Ralph R Stein, Ruediger Fahl, Kirsten |
| author_facet | Kolling, Henriette Marie Schneider, Ralph R Stein, Ruediger Fahl, Kirsten |
| collection | Datos científicos de ciencias marinas y ambientales |
| contents | 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 (g/cm3), TOC = total organic carbon, BM = biomarker concentration (μg/gSed), AR = accumulation rate. Equation (2) was also applied to calculate BSi accumulation rates. After the determination of biomarker concentrations, the PIP25 index was calculated as follows: PIP25 = IP25/(IP25 + (PM x c)) (4) with PM = phytoplankton marker (brassicasterol (PBIP25), dinosterol (PDIP25) or HBI III (Z) (PIIIIP25)) and c = balance factor. The balance factor c is the ratio of mean IP25 concentration and mean sterol concentration, counterbalancing generally higher concentrations of sterols compared to IP25. As HBI III (Z) and IP25 showed similar concentrations in the initial studies from the Barents Sea lead to the assumption that the use of the balance factor c unnecessary in the calculation of the PIIIIP25 index (Belt et al., 2015; Smik et al., 2016). |
| format | Dataset Open Access |
| id | pangaea_https___doi_org_10_1594_PANGAEA_949065 |
| institution | PANGAEA |
| language | en |
| publishDate | 2022 |
| publisher | PANGAEA |
| record_format | pangaea |
| spellingShingle | Biomarker concentrations in gravity core MSM45_19-2 Kolling, Henriette Marie Schneider, Ralph R Stein, Ruediger Fahl, Kirsten 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, per unit mass total organic carbon; 24-Methylcholest-5-en-3beta-ol, per unit sediment mass; 24-Methylcholesta-5,22E-dien-3beta-ol, per unit mass total organic carbon; 24-Methylcholesta-5,22E-dien-3beta-ol, per unit sediment mass; 4alpha,23,24-Trimethyl-5alpha-cholest-22E-en-3beta-ol, per unit mass total organic carbon; 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; Accumulation rate, 24-Methylcholest-5-en-3beta-ol per year; Accumulation rate, 24-Methylcholesta-5,22E-dien-3beta-ol per year; Accumulation rate, 4alpha,23,24-Trimethyl-5alpha-cholest-22E-en-3beta-ol per year; Accumulation rate, highly branched isoprenoids (Z), triunsatured per year; Accumulation rate per year; Biomarker; brassica sterol; campesterol; DEPTH, sediment/rock; dionsterol; GC; Gravity corer; HBI III; Highly branched isoprenoids (Z), triunsatured, per unit mass total organic carbon; Highly branched isoprenoids (Z), 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 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 (g/cm3), TOC = total organic carbon, BM = biomarker concentration (μg/gSed), AR = accumulation rate. Equation (2) was also applied to calculate BSi accumulation rates. After the determination of biomarker concentrations, the PIP25 index was calculated as follows: PIP25 = IP25/(IP25 + (PM x c)) (4) with PM = phytoplankton marker (brassicasterol (PBIP25), dinosterol (PDIP25) or HBI III (Z) (PIIIIP25)) and c = balance factor. The balance factor c is the ratio of mean IP25 concentration and mean sterol concentration, counterbalancing generally higher concentrations of sterols compared to IP25. As HBI III (Z) and IP25 showed similar concentrations in the initial studies from the Barents Sea lead to the assumption that the use of the balance factor c unnecessary in the calculation of the PIIIIP25 index (Belt et al., 2015; Smik et al., 2016). |
| title | Biomarker concentrations in gravity core MSM45_19-2 |
| topic | 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, per unit mass total organic carbon; 24-Methylcholest-5-en-3beta-ol, per unit sediment mass; 24-Methylcholesta-5,22E-dien-3beta-ol, per unit mass total organic carbon; 24-Methylcholesta-5,22E-dien-3beta-ol, per unit sediment mass; 4alpha,23,24-Trimethyl-5alpha-cholest-22E-en-3beta-ol, per unit mass total organic carbon; 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; Accumulation rate, 24-Methylcholest-5-en-3beta-ol per year; Accumulation rate, 24-Methylcholesta-5,22E-dien-3beta-ol per year; Accumulation rate, 4alpha,23,24-Trimethyl-5alpha-cholest-22E-en-3beta-ol per year; Accumulation rate, highly branched isoprenoids (Z), triunsatured per year; Accumulation rate per year; Biomarker; brassica sterol; campesterol; DEPTH, sediment/rock; dionsterol; GC; Gravity corer; HBI III; Highly branched isoprenoids (Z), triunsatured, per unit mass total organic carbon; Highly branched isoprenoids (Z), 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 |
| url | https://doi.org/10.1594/PANGAEA.949065 |