A Thesis Submitted to the University of North Carolina Wilmington in Partial Fulfillment Of the Requirements for the Degree of Master of Science
- UNCW Author/Contributor (non-UNCW co-authors, if there are any, appear on document)
- Lisa A. Thatcher (Creator)
- Institution
- The University of North Carolina Wilmington (UNCW )
- Web Site: http://library.uncw.edu/
- Advisor
- G. Brooks Avery
Abstract: Global warming has generated extensive research into the sources and removal
mechanisms for the greenhouse gases carbon dioxide and methane. Recent research, in
which sulfate was added to freshwater and methanogenic brackish sediments, showed
that under sulfate-reducing conditions rates of carbon remineralization were more rapid.
Therefore, less carbon should be stored in these systems under saline conditions.
In the current study, rates of carbon remineralization and storage were compared
in Cape Fear River estuarine sediments with naturally-occurring spatial and temporal
salinity variations. Trends were not evident along a salinity gradient for the percent
organic matter content of sediments, sediment accumulation rates, or the total amount of
carbon remineralized. These results show that there are no clear-cut patterns for
biogeochemical parameters along a salinity gradient, likely due to variability in both
primary productivity and remineralization rates. Although the quantity and quality of
organic matter are generally thought to affect remineralization rates, rates in this study
were controlled by sulfate concentrations. Most sediments responded to sulfate
concentration increases with more rapid remineralization rates, showing that sulfate
variations can potentially affect carbon storage in estuarine sediments.
An unexpected microbial process was observed during the experiments conducted
for this study. The two main processes by which sediments are remineralized in the
estuary are sulfate reduction and methane production. Sulfate reduction has generally
been shown to out-compete and inhibit methane production via mutually exclusive
biogeochemical zonation through competitive inhibition. However, for the first time the
coexistence of the two processes at rates of similar magnitudes was observed. A novel approach for calculating below-ground primary production within
estuarine wetlands and carbon flux from estuarine wetlands, using sediment
remineralization rates, 137Cesium accumulation rates, and above-ground biomass
measurements, is presented in this study. The largest amount of carbon fluxed from a site
that contained the most above-ground biomass during the growing season. This study has
shown that remineralization rates in estuarine sediments could potentially respond to
sulfate variations on a short-term basis, supporting the idea that stored carbon could be
released to the atmosphere during a rapid sea level rise.
A Thesis Submitted to the University of North Carolina Wilmington in Partial Fulfillment Of the Requirements for the Degree of Master of Science
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Additional Information
- Publication
- Thesis
- A Thesis Submitted to the University of North Carolina Wilmington in Partial Fulfillment Of the Requirements for the Degree of Master of Science
- Language: English
- Date: 2009
- Keywords
- Carbon cycle (Biogeochemistry), Coastal ecology, Estuarine ecology--North Carolina--Cape Fear River Estuary, Estuarine sediments--North Carolina--Cape Fear River Estuary
- Subjects
- Estuarine sediments -- North Carolina -- Cape Fear River Estuary
- Carbon cycle (Biogeochemistry)
- Estuarine ecology -- North Carolina -- Cape Fear River Estuary
- Coastal ecology