Carbon transfer dynamics from bomb-14C and δ13C time series of a laminated stalagmite from SW France—modelling and comparison with other stalagmite records

Genty, Dominique; Massault, M.

doi:10.1016/s0016-7037(99)00122-2

Cited by 140 publications

(100 citation statements)

References 38 publications

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“…By correcting the 14 C results for the deadcarbon contribution (with  13 C assumed to be unaffected) using slightly different assumed values for the contamination in the 2 experiments (0.6% in 1975 and 0.8% in 1977), they found that all of the experimentally determined values could be brought into close agreement, with a mean value of the 14 C-13 C fractionation ratio of 2.3. This value was subsequently adopted in influential modeling papers on the geochemistry and dating of groundwater and speleothems (Fontes 1992;Genty and Massault 1999) and still appears in some publications by researchers attempting to model speleothem 14 C (Fohlmeister et al 2011;Hodge et al 2011;Rudzka et al 2011).…”

Section: Results and Correctionsmentioning

confidence: 99%

Are the Fractionation Corrections Correct: Are the Isotopic Shifts for ¹⁴C/¹²C Ratios in Physical Processes and Chemical Reactions Really Twice Those for ¹³C/¹²C?

Southon¹

2011

Radiocarbon

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ABSTRACT. Conventional radiocarbon calculations correct for isotopic fractionation using an assumed value of 2.0 for the fractionation of 14 C relative to 13 C. In other words, isotopic discrimination in physical and chemical processes is assumed to cause relative shifts in 14 C/ 12 C ratios that are exactly double those of 13 C/ 12 C. This paper analyzes a 1984 experiment that produced a value for the fractionation ratio in photosynthesis of 2.3, which is used to this day by some researchers in the fields of hydrology and speleothem geochemistry. While the value of 2.3 is almost certainly incorrect, theoretical work suggests that the true value may indeed deviate from 2.0, which would have significant implications for 14 C calculations.

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Section: Results and Correctionsmentioning

confidence: 99%

Are the Fractionation Corrections Correct: Are the Isotopic Shifts for ¹⁴C/¹²C Ratios in Physical Processes and Chemical Reactions Really Twice Those for ¹³C/¹²C?

Southon¹

2011

Radiocarbon

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“…Genty and Massault, 1999;Fohlmeister et al, 2010Fohlmeister et al, , 2011aGriffiths et al, 2012;and Rudzka-Phillips et al, 2013) estimated the radiocarbon activity of soil CO 2 (a 14 C g ) using the equations originally proposed by Genty and Massault (1999):…”

Section: Soil Carbon Modelmentioning

confidence: 99%

“…Under the assumption the carbonate dissolution regime at a site can be taken to be relatively invariable over the twentieth century, several recent studies have interpreted speleothem-based a 14 C records of the twentieth century atmospheric a 14 C bomb peak as records of soil a 14 CO 2 (e.g. Genty and Massault, 1999;Fohlmeister et al, 2010Fohlmeister et al, , 2011aGriffiths et al, 2012;and Rudzka-Phillips et al, 2013). These studies have employed a simple soil carbon model to inversely model the age distribution of SOM at karst sites using speleothem a 14 C bomb peak records, in part to investigate the potential of speleothems as sensitive recorders of past soil carbon dynamics.…”

Section: Introductionmentioning

confidence: 99%

Radiocarbon evidence for decomposition of aged organic matter in the vadose zone as the main source of speleothem carbon

Noronha

Johnson

Southon

et al. 2015

Quaternary Science Reviews

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a b s t r a c tSeveral recent studies have used records of the radiocarbon ( 14 C) bomb peak in speleothems to inversely model the soil a 14 CO 2 and the age distribution of soil organic material (SOM) above caves, in part to investigate the potential of speleothems as sensitive records of past SOM dynamics. The results of these modeling studies have suggested that soil CO 2 at karst sites is derived primarily from the decomposition of SOM with turnover times on the order of decades to centuries. This result is in stark contrast with observations of soil a 14 CO 2 at non-karst sites, which indicate that soil CO 2 is derived primarily from root respiration and decomposition of SOM with much shorter turnover times. This discrepancy suggests that SOM in karst settings may have a very different age distribution than sites that have been studied previously and/or that soil CO 2 is not the main source of speleothem carbon. To help resolve this discrepancy, we present an improved inverse model which we use to estimate the age of CO 2 above several caves. We also present results from a detailed case study of soil carbon dynamics at Heshang Cave, China. This work demonstrates that SOM in karst sites may be much older than SOM in non-karst soils that have been studied previously, but that CO 2 produced in the shallow soil zone is unlikely to be the main source of speleothem carbon. A review of the literature suggests that the most likely explanation for the aforementioned discrepancy is that decomposition of down-washed SOM in the vadose zone is the dominant source of speleothem carbon.

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“…3). However, DCF varies considerably 579 depending on cave and climatic settings (Genty et al 1999), so that DCF from a 580 single stalagmite (e.g., HS4) cannot be used to calibrate samples from other 581 locations. Available published data suggest that very different and sample-582 specific relationships between DCF and  13 C exist, and no clear pattern related to 583 climate or cave settings is apparent (Suppl .…”

mentioning

confidence: 99%

A novel approach for construction of radiocarbon-based chronologies for speleothems

Lechleitner

Fohlmeister

McIntyre

et al. 2016

Quaternary Geochronology

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Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. China, and is then applied to an undated stalagmite from southern Poland. 46The new method will not replace high-precision U-Th measurements, 47 because the precision of the technique is difficult to quantify. However, it 48 provides a means for dating certain stalagmites undateable by 49 conventional U-Th methods and for refining coarse U-Th chronologies. 50 51

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Carbon transfer dynamics from bomb-14C and δ13C time series of a laminated stalagmite from SW France—modelling and comparison with other stalagmite records

Cited by 140 publications

References 38 publications

Are the Fractionation Corrections Correct: Are the Isotopic Shifts for ¹⁴C/¹²C Ratios in Physical Processes and Chemical Reactions Really Twice Those for ¹³C/¹²C?

Are the Fractionation Corrections Correct: Are the Isotopic Shifts for ¹⁴C/¹²C Ratios in Physical Processes and Chemical Reactions Really Twice Those for ¹³C/¹²C?

Radiocarbon evidence for decomposition of aged organic matter in the vadose zone as the main source of speleothem carbon

A novel approach for construction of radiocarbon-based chronologies for speleothems

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Carbon transfer dynamics from bomb-14C and δ13C time series of a laminated stalagmite from SW France—modelling and comparison with other stalagmite records

Cited by 140 publications

References 38 publications

Are the Fractionation Corrections Correct: Are the Isotopic Shifts for 14C/12C Ratios in Physical Processes and Chemical Reactions Really Twice Those for 13C/12C?

Are the Fractionation Corrections Correct: Are the Isotopic Shifts for 14C/12C Ratios in Physical Processes and Chemical Reactions Really Twice Those for 13C/12C?

Radiocarbon evidence for decomposition of aged organic matter in the vadose zone as the main source of speleothem carbon

A novel approach for construction of radiocarbon-based chronologies for speleothems

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Are the Fractionation Corrections Correct: Are the Isotopic Shifts for ¹⁴C/¹²C Ratios in Physical Processes and Chemical Reactions Really Twice Those for ¹³C/¹²C?

Are the Fractionation Corrections Correct: Are the Isotopic Shifts for ¹⁴C/¹²C Ratios in Physical Processes and Chemical Reactions Really Twice Those for ¹³C/¹²C?