Tracking Organic Matter from Source to Sink in the Waiapu River Watershed, New Zealand: A Geochemical Perspective

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dc.contributor.advisor Paul Liu, Committee Member en_US
dc.contributor.advisor Dave DeMaster, Committee Member en_US
dc.contributor.advisor Neal Blair, Committee Chair en_US
dc.contributor.advisor Elana Leithold, Committee Co-Chair en_US
dc.contributor.advisor Elizabeth Nichols, Committee Member en_US Thompson, Catherine Elizabeth en_US 2010-04-02T18:30:56Z 2010-04-02T18:30:56Z 2010-03-04 en_US
dc.identifier.other etd-08182009-151824 en_US
dc.description.abstract The significant contribution of small mountainous river systems, including the Waiapu River on New Zealand’s East Cape, to the global fluvial sediment supply motivates investigation into the processes that influence the character and composition of the organic carbon that they carry. Organic matter preserved in continental margin sediments originates from terrestrial sources such as kerogen, fresh and aged soil carbon, as well as marine sources. Due to the reactivity of marine carbon in the seabed, terrestrial sources of carbon are preferentially preserved unaltered. Therefore, identification of specific terrestrial sources of sediment from the watershed preserved on the continental margin can facilitate interpretation of the organic geochemical record and enable reconstruction of the watershed history. Carbon and nitrogen isotopic analyses and polycyclic aromatic hydrocarbons have been used to apportion terrestrial carbon sources preserved on the shelf, specifically to resolve aged soil contributions. Spatial geochemical patterns on the margin appear to be complicated by structural deformation of the shelf and its influence on marine sediment dynamics. Resolution of riverine sources suggests that gullying, bank failure, and sheetwashing are the chronic geomorphic process delivering most of the organic carbon to the Waiapu sedimentary system. The middle and outer Waiapu continental shelf buries an average of 59 Gg C/y. Relative to the 200 Gg C/y delivered by the Waiapu River to the ocean, approximately 23% of the riverine carbon is retained on the mid- to outer shelf, matching the sediment inventory. Radiocarbon analysis of DIC indicates that there is no apparent oxidation of kerogen in the seabed. Stable carbon isotopic signatures suggest minimal oxidation of modern terrestrial carbon, signifying that the 77% of the riverine carbon not accounted for has likely been retained and potentially oxidized on the inner shelf or escaped to the slope or beyond the established boundaries of the mid- to outer shelf. en_US
dc.rights I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dis sertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to NC State University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. en_US
dc.subject sediment en_US
dc.subject polycyclic aromatic hydrocarbons en_US
dc.subject Waiapu River en_US
dc.subject New Zealand en_US
dc.subject kerogen oxidation en_US
dc.subject carbon isotopes en_US
dc.subject nitrogen isotopes en_US
dc.subject riverine organic carbon en_US
dc.title Tracking Organic Matter from Source to Sink in the Waiapu River Watershed, New Zealand: A Geochemical Perspective en_US PhD en_US dissertation en_US Marine, Earth and Atmospheric Sciences en_US

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