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Prediction of atmospheric delta (super 13) CO (sub 2) using plant cuticle isolated from fluvial sediment; tests across a gradient in salt content

A. Hope Jahren and Nan Crystal Arens
Prediction of atmospheric delta (super 13) CO (sub 2) using plant cuticle isolated from fluvial sediment; tests across a gradient in salt content
Palaios (June 2009) 24 (6): 394-401

Abstract

In order to test the assertion that the carbon-isotopic composition of the ancient atmosphere (delta (super 13) CO (sub 2) ) can be reconstructed from the carbon-isotopic composition of fossil terrestrial plant tissues across a variety of environments, the delta (super 13) C value of land-plant tissues isolated from modern fluvial sediments was compared to that of today's atmosphere. Plant stem and leaf fragments were isolated from organic carbon-rich sediments of the Black River in Jamaica, which drains a basin containing only C3 ecosystems. Sediment was sampled at 12 sites along a dissolved salt-content gradient, from the coastal plain to near its mouth, which allowed evaluation of the effect of salt influence on the organic carbon-isotope signature. Many properties of the sediment varied systematically with salt content (e.g., mass-percent carbonate, abundance of palynomorphs, delta (super 13) C and delta (super 18) O values of carbonate), confirming a significant and increasing marine influence closer to the mouth of the river. The delta (super 13) C value of total organic carbon systematically decreased by approximately 2 per mil with increased NaCl concentration, indicating the presence of a mixing line between marine and terrestrial organic inputs. In contrast, for leaf and stem isolates, there was no significant dependence of delta (super 13) C value on NaCl concentration, suggesting that the isotopic signature of the integrated terrestrial contribution is independent of the salt content of the depositional environment. The mean values of all isolates retrieved from the sediments predicted a delta (super 13) CO (sub 2) value of -9.7 (+ or -1.0) for leaf material and -8.2 (+ or -1.7) for stems. Both of these values are within approximately 1 per mil of recent regional-scale measurements of atmospheric delta (super 13) CO (sub 2) value.


ISSN: 0883-1351
Serial Title: Palaios
Serial Volume: 24
Serial Issue: 6
Title: Prediction of atmospheric delta (super 13) CO (sub 2) using plant cuticle isolated from fluvial sediment; tests across a gradient in salt content
Affiliation: University of Hawaii, Department of Geology and Geophysics, Honolulu, HI, United States
Pages: 394-401
Published: 200906
Text Language: English
Publisher: Society for Sedimentary Geology, Tulsa, OK, United States
References: 49
Accession Number: 2009-064976
Categories: Environmental geologyIsotope geochemistry
Document Type: Serial
Bibliographic Level: Analytic
Annotation: NSF Grant EAR-0634929
Illustration Description: illus. incl. 4 tables, sketch map
N18°00'00" - N18°00'00", W77°50'60" - W77°50'60"
Secondary Affiliation: Hobart and William Smith Colleges, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by SEPM (Society for Sedimentary Geology), Tulsa, OK, United States
Update Code: 200935
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