Biosynthetic isotope fractionation negligibly impacts biomarker 14C ages

Hemingway, Jordon D.

doi:10.1016/j.orggeochem.2021.104267

Cited by 1 publication

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“…However, CSRA has two main challenges: The most significant is the input of unknown amounts of extraneous carbon to a sample with unknown mass and unknown radiocarbon content (here expressed as F 14 C-values as described in Hemingway (2021) during the analytical procedure (Shah and Pearson 2007). This so-called process or procedural blank—if large enough compared to the sample size—alters the sample’s radiocarbon age; hence a correction is mandatory.…”

Section: Introductionmentioning

confidence: 99%

ASSESSING ¹⁴C BLANKS IN THE SMALL-SCALE ANALYSIS OF N-ALKANE COMPOUND-SPECIFIC-RADIOCARBON-ANALYSIS

Reetz,

Friedrich,

Birk

et al. 2024

Radiocarbon

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Compound-specific radiocarbon analysis (CSRA) provides the possibility to date sample material at a molecular level. N-alkanes are considered as specific compounds with high potential to CSRA. As these compounds originate from plant waxes, their radiocarbon (14C) analysis can provide valuable information about the age and origin of organic materials. This helps to reconstruct and understand environmental conditions and changes in vegetation in the past. However, CSRA has two main challenges: The small sample size of CSRA samples, making them extremely sensitive to blank effects, and the input of unknown amounts of extraneous carbon during the analytical procedure. According to the previous study from Sun and co-workers, we used different-sized aliquots of leaves Fagus sylvatica (nC27, nC29) and Festuca rubra agg (nC31, nC33) as modern standards and two commercial standards (nC26, nC28) as fossil standards for blank determination. A third commercial standard (nC27) with predetermined radiocarbon content of F14C = 0.71 (14C age of 2700 BP) serves to evaluate the blank correction. We found that the blank assessment of Sun and co-workers is also applicable to n-alkanes, with a minimum sample size of 15 µg C for dependable CSRA dates. We determined that the blank introduced during the analytical procedure has a mass of (4.1 ± 0.7) µg carrying a radiocarbon content of F14C = 0.25 ± 0.05. Applying the blank correction to a sediment sample from Lake Holzmaar (Germany) shows that all four isolated n-alkanes have similar 14C ages. However, the bulk material of the sediment and branches found in the sediment core are younger than the CSRA dates. We conclude that the disparity between the actual age of analysed organic material and the age inferred from radiocarbon results, which can occur in sediment traps due to delayed deposition, is the reason for the CSRA age.

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Section: Introductionmentioning

confidence: 99%

ASSESSING ¹⁴C BLANKS IN THE SMALL-SCALE ANALYSIS OF N-ALKANE COMPOUND-SPECIFIC-RADIOCARBON-ANALYSIS

Reetz,

Friedrich,

Birk

et al. 2024

Radiocarbon

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Biosynthetic isotope fractionation negligibly impacts biomarker 14C ages

Cited by 1 publication

References 46 publications

ASSESSING ¹⁴C BLANKS IN THE SMALL-SCALE ANALYSIS OF N-ALKANE COMPOUND-SPECIFIC-RADIOCARBON-ANALYSIS

ASSESSING ¹⁴C BLANKS IN THE SMALL-SCALE ANALYSIS OF N-ALKANE COMPOUND-SPECIFIC-RADIOCARBON-ANALYSIS

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Biosynthetic isotope fractionation negligibly impacts biomarker 14C ages

Cited by 1 publication

References 46 publications

ASSESSING 14C BLANKS IN THE SMALL-SCALE ANALYSIS OF N-ALKANE COMPOUND-SPECIFIC-RADIOCARBON-ANALYSIS

ASSESSING 14C BLANKS IN THE SMALL-SCALE ANALYSIS OF N-ALKANE COMPOUND-SPECIFIC-RADIOCARBON-ANALYSIS

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ASSESSING ¹⁴C BLANKS IN THE SMALL-SCALE ANALYSIS OF N-ALKANE COMPOUND-SPECIFIC-RADIOCARBON-ANALYSIS

ASSESSING ¹⁴C BLANKS IN THE SMALL-SCALE ANALYSIS OF N-ALKANE COMPOUND-SPECIFIC-RADIOCARBON-ANALYSIS