Short organic carbon turnover time and narrow C-14 age spectra in early Holocene wetland paleosols
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Vetter_et_al-2017-Geochemistry ...
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AMER GEOPHYSICAL UNIONCitation
Short organic carbon turnover time and narrow 14C age spectra in early Holocene wetland paleosols 2017, 18 (1):142 Geochemistry, Geophysics, GeosystemsRights
© 2016. The Authors. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License.Collection Information
This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.Abstract
Paleosols contain information about the rates of soil organic carbon turnover when the soil was actively forming. However, this temporal information is often difficult to interpret without tight stratigraphic control on the age of the paleosol. Here we apply ramped pyrolysis/oxidation (Ramped PyrOx) C-14 analyses to evaluate age spectra of transgressive early Holocene paleosols from the Mississippi Delta in southeastern Louisiana, USA. We find C-14 age spectra from soil organic matter (SOM) in both paleosols and overlying basal peats that represent variability in age that is close to, or only slightly greater than, analytical uncertainty of C-14 measurements, despite different sources of carbon with likely disparate ages. Such age spectra have not previously been observed in the sedimentary record. Here they indicate vigorous soil carbon turnover prior to burial, which homogenized C-14 ages within SOM across the entire thermochemical spectrum. The weighted bulk C-14 ages from Ramped PyrOx of paleosols and overlying peats are identical within analytical and process-associated uncertainty, and corroborate C-14 ages from charcoal fragments and plant macrofossils from the overlying peat. The youngest ages from Ramped PyrOx age spectra may also potentially be applied as chronometers for stratigraphic burial ages. Our results suggest rapid turnover (<<300 years) of carbon in these soils relative to input of allochthonous carbon, indicating that the C-14 age of different soil components is decoupled from thermochemical stability and instead reflects vigorous turnover processes. The concurrence of paleosol and peat C-14 ages also suggests that pedogenic processes were linked with the development of coastal marshes, and that the priming effect potentially masked the signal of allochthonous carbon inputs during sea level rise.Note
6 month embargo; First published: 22 January 2017ISSN
15252027Version
Final published versionSponsors
U.S. Department of Energy through the National Institute for Climatic Change Research Coastal Center; National Science Foundation [OCE-1502588, OCE-1502753]; Tulane UniversityAdditional Links
http://doi.wiley.com/10.1002/2016GC006526ae974a485f413a2113503eed53cd6c53
10.1002/2016GC006526
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Except where otherwise noted, this item's license is described as © 2016. The Authors. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License.