Dissertation/Thesis Abstract

Clay mineral and sedimentary controls on sorptive preservation of terrestrial organic matter: Implications for organic matter reactivity in continental margin sediments
by Robinson, Amelia Carol, Ph.D., University of California, Davis, 2010, 189; 3427428
Abstract (Summary)

Deciphering terrestrial climatic conditions in marine sediments as well as overall terrestrial contributions to carbon preservation in continental margins requires that the biogeochemical signatures faithfully record vegetation and soil organic matter compositions of the watershed from which it was derived. How these compounds change from the time of their formation to their export and burial in marine environments is poorly constrained. This research addressed changes in organic matter-clay mineral systems in response to sorption of lignin phenols, desorption through a salinity gradient, and secondary uptake of amino acids. Scaling up from single clay mineral and lignin phenol standards to heterogeneous systems using plant leachates and soils of contrasting mineralogy, provided supporting evidence that clay minerals present in these soils do, in fact, contribute significantly to OC and lignin phenol sorption. The fact that kaolinite and montmorillonite sorbed similar quantities across these different particle systems despite differences in mineral specific surface area, suggests that mineral-specific reactivity may be more important than typically considered. Further contrasts in how lignin phenols desorbed from these two minerals highlights an additional control on OM compositions and source and diagenetic information derived from lignin phenols preserved in continental margin sediments. Retention of lignin phenols on mineral surfaces (∼60% of initial amounts sorbed, effectively priming the surfaces) resulted in 2-3 times more glutamic acid sorbed relative to mineral surfaces without lignin phenol-priming. As such, the cumulative history that OM-clay mineral particles experience, ultimately determines their reactivity in continental margin sediments. Continental margin sediments apparently contain much less terrestrial organic matter than can be accounted for based on inputs, and thus may reflect enhanced burial of marine organic matter due to assistance from terrestrial-primed mineral surfaces. An overarching finding of this research is that particulate OM-clay mineral systems undergo molecular-level fractionation at all stages of processing from terrestrial source to depositional zones in continental margins.

Indexing (document details)
Advisor: Montanez, Isabel P.
Commitee: Hernes, Peter J., Rustad, James R.
School: University of California, Davis
Department: Geology
School Location: United States -- California
Source: DAI-B 71/12, Dissertation Abstracts International
Subjects: Geology, Biogeochemistry, Sedimentary Geology
Keywords: Amino acids, Clay mineral, Lignin, Organic carbon, Salinity, Sedimentary controls, Sorption
Publication Number: 3427428
ISBN: 978-1-124-31629-1
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