Geochemical controls on the distribution and composition of biogenic and sedimentary carbon
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution February 2017 Organic carbon (OC) preserved in marine sediments acts as a reduced carbon sink that balances the global...
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Massachusetts Institute of Technology and Woods Hole Oceanographic Institution
2017
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ftwhoas:oai:darchive.mblwhoilibrary.org:1912/8762 2023-05-15T17:36:05+02:00 Geochemical controls on the distribution and composition of biogenic and sedimentary carbon Estes, Emily R. 2017-02 https://hdl.handle.net/1912/8762 en_US eng Massachusetts Institute of Technology and Woods Hole Oceanographic Institution WHOI Theses https://hdl.handle.net/1912/8762 doi:10.1575/1912/8762 doi:10.1575/1912/8762 Biosphere Nitrogen Microorganisms Knorr (Ship : 1970-) Cruise KN223 Thesis 2017 ftwhoas https://doi.org/10.1575/1912/8762 2022-05-28T22:59:50Z Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution February 2017 Organic carbon (OC) preserved in marine sediments acts as a reduced carbon sink that balances the global carbon cycle. Understanding the biogeochemical mechanisms underpinning the balance between OC preservation and degradation is thus critical both to quantifying this carbon reservoir and to estimating the extent of life in the deep subsurface biosphere. This work utilizes bulk and spatially-resolved X-ray absorption spectroscopy to characterize the OC content and composition of various environmental systems in order to identify the role of minerals and surrounding geochemistry in organic carbon preservation in sediments. Biogenic manganese (Mn) oxides formed either in pure cultures of Mn-oxidizing microorganisms, in incubations of brackish estuarine waters, or as ferromanganese deposits in karstic cave systems rapidly associate with OC following precipitation. This association is stable despite Mn oxide structural ripening, suggesting that mineral-associated OC could persist during early diagenetic reactions. OC associated with bacteriogenic Mn oxides is primarily proteinaceous, including intact proteins involved in Mn oxidation and likely oxide nucleation and aggregation. Pelagic sediments from 16 sites underlying the South Pacific and North Atlantic gyres and spanning a gradient of sediment age and redox state were analyzed in order to contrast the roles of oxygen exposure, OC recalcitrance, and mineral-based protection of OC as preservation mechanisms. OC and nitrogen concentrations measured at these sites are among the lowest globally (<0.1%) and, to a first order, scale with sediment oxygenation. In the deep subsurface, however, molecular recalcitrance becomes more important than oxygen exposure time in protecting OC against remineralization. Deep OC consists of primarily amide and carboxylic carbon in a ... Thesis North Atlantic Woods Hole Scientific Community: WHOAS (Woods Hole Open Access Server) Pacific Woods Hole, MA |
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Open Polar |
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Woods Hole Scientific Community: WHOAS (Woods Hole Open Access Server) |
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ftwhoas |
language |
English |
topic |
Biosphere Nitrogen Microorganisms Knorr (Ship : 1970-) Cruise KN223 |
spellingShingle |
Biosphere Nitrogen Microorganisms Knorr (Ship : 1970-) Cruise KN223 Estes, Emily R. Geochemical controls on the distribution and composition of biogenic and sedimentary carbon |
topic_facet |
Biosphere Nitrogen Microorganisms Knorr (Ship : 1970-) Cruise KN223 |
description |
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution February 2017 Organic carbon (OC) preserved in marine sediments acts as a reduced carbon sink that balances the global carbon cycle. Understanding the biogeochemical mechanisms underpinning the balance between OC preservation and degradation is thus critical both to quantifying this carbon reservoir and to estimating the extent of life in the deep subsurface biosphere. This work utilizes bulk and spatially-resolved X-ray absorption spectroscopy to characterize the OC content and composition of various environmental systems in order to identify the role of minerals and surrounding geochemistry in organic carbon preservation in sediments. Biogenic manganese (Mn) oxides formed either in pure cultures of Mn-oxidizing microorganisms, in incubations of brackish estuarine waters, or as ferromanganese deposits in karstic cave systems rapidly associate with OC following precipitation. This association is stable despite Mn oxide structural ripening, suggesting that mineral-associated OC could persist during early diagenetic reactions. OC associated with bacteriogenic Mn oxides is primarily proteinaceous, including intact proteins involved in Mn oxidation and likely oxide nucleation and aggregation. Pelagic sediments from 16 sites underlying the South Pacific and North Atlantic gyres and spanning a gradient of sediment age and redox state were analyzed in order to contrast the roles of oxygen exposure, OC recalcitrance, and mineral-based protection of OC as preservation mechanisms. OC and nitrogen concentrations measured at these sites are among the lowest globally (<0.1%) and, to a first order, scale with sediment oxygenation. In the deep subsurface, however, molecular recalcitrance becomes more important than oxygen exposure time in protecting OC against remineralization. Deep OC consists of primarily amide and carboxylic carbon in a ... |
format |
Thesis |
author |
Estes, Emily R. |
author_facet |
Estes, Emily R. |
author_sort |
Estes, Emily R. |
title |
Geochemical controls on the distribution and composition of biogenic and sedimentary carbon |
title_short |
Geochemical controls on the distribution and composition of biogenic and sedimentary carbon |
title_full |
Geochemical controls on the distribution and composition of biogenic and sedimentary carbon |
title_fullStr |
Geochemical controls on the distribution and composition of biogenic and sedimentary carbon |
title_full_unstemmed |
Geochemical controls on the distribution and composition of biogenic and sedimentary carbon |
title_sort |
geochemical controls on the distribution and composition of biogenic and sedimentary carbon |
publisher |
Massachusetts Institute of Technology and Woods Hole Oceanographic Institution |
publishDate |
2017 |
url |
https://hdl.handle.net/1912/8762 |
geographic |
Pacific |
geographic_facet |
Pacific |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
doi:10.1575/1912/8762 |
op_relation |
WHOI Theses https://hdl.handle.net/1912/8762 doi:10.1575/1912/8762 |
op_doi |
https://doi.org/10.1575/1912/8762 |
op_publisher_place |
Woods Hole, MA |
_version_ |
1766135447622254592 |