Stable carbon isotopes as potential sea-level indicators in salt marshes, North Carolina, USA

Andrew C. Kemp, Christopher H. Vane, Benjamin Horton, Stephen J. Culver

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Abstract

We compared the use of δ13C values and C:N ratios from salt-marsh sediments to reconstruct relative sea level (RSL) with an established approach using foraminifera. Analysis of bulk-organic sediment and plant samples collected along transects at two sites in North Carolina, USA demonstrates that sediment δ13C values can be used to distinguish between Spartina alterniflora-dominated low marsh (C4 photosynthetic pathway, δ13C values from -17.6‰ to 16.1‰) and Juncus roemerianus-dominated high marsh (C3 photosynthetic pathway, δ13C values from -28.2‰ to -21.8‰) environments. Juncus roemerianus plants undergo little decompositional change in δ13C (average 0.8‰), although there is a clear difference between Spartina alterniflora tissue and bulk-organic sediments (approximately 4‰). C:N ratios on bulk-organic sediment from freshwater upland and salt-marsh environments converge during early diagenesis, rendering them of little use in reconstructing RSL. The utility of δ13C values as a sea-level indicator is limited by the elevational range of C4 plants, making it difficult to recognize salt-marsh subenvironments and improve the precision of RSL reconstructions. Furthermore, Juncus roemerianus-dominated high marsh and freshwater upland sediments cannot be adequately distinguished with δ13C values.

Original languageEnglish (US)
Pages (from-to)623-636
Number of pages14
JournalHolocene
Volume20
Issue number4
DOIs
Publication statusPublished - Jun 1 2010

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All Science Journal Classification (ASJC) codes

  • Global and Planetary Change
  • Archaeology
  • Ecology
  • Earth-Surface Processes
  • Palaeontology

Keywords

  • Carbon isotope ratios
  • Foraminifera
  • North Carolina
  • Salt marsh
  • Sea level

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