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Carbon and sediment accumulation in the Everglades (USA) during the past 4000 years: rates, drivers, and sources of error

Journal of Geophysical Research G: Biogeosciences

By:
, , , , and
DOI: 10.1029/2011JG001821

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Abstract

Tropical and sub-tropical wetlands are considered to be globally important sources for greenhouse gases but their capacity to store carbon is presumably limited by warm soil temperatures and high rates of decomposition. Unfortunately, these assumptions can be difficult to test across long timescales because the chronology, cumulative mass, and completeness of a sedimentary profile are often difficult to establish. We therefore made a detailed analysis of a core from the principal drainage outlet of the Everglades of South Florida, to assess these problems and determine the factors that could govern carbon accumulation in this large sub-tropical wetland. Accelerator mass spectroscopy dating provided direct evidence for both hard-water and open-system sources of dating errors, whereas cumulative mass varied depending upon the type of method used. Radiocarbon dates of gastropod shells, nevertheless, seemed to provide a reliable chronology for this core once the hard-water error was quantified and subtracted. Long-term accumulation rates were then calculated to be 12.1 g m-2 yr-1 for carbon, which is less than half the average rate reported for northern and tropical peatlands. Moreover, accumulation rates remained slow and relatively steady for both organic and inorganic strata, and the slow rate of sediment accretion ( 0.2 mm yr-1) tracked the correspondingly slow rise in sea level (0.35 mm yr-1 ) reported for South Florida over the past 4000 years. These results suggest that sea level and the local geologic setting may impose long-term constraints on rates of sediment and carbon accumulation in the Everglades and other wetlands.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Carbon and sediment accumulation in the Everglades (USA) during the past 4000 years: rates, drivers, and sources of error
Series title:
Journal of Geophysical Research G: Biogeosciences
DOI:
10.1029/2011JG001821
Volume
117
Issue:
G3
Year Published:
2012
Language:
English
Publisher:
American Geophysical Union
Publisher location:
Washington, D.C.
Contributing office(s):
Fort Collins Science Center
Description:
18 p.;
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Journal of Geophysical Research G: Biogeosciences
First page:
G03026
Country:
United States
State:
Florida
City:
Everglades