Clay Mineralogy and Organic Carbon Associations in Two Adjacent Watersheds, New Zealand

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dc.contributor.advisor Dr. Neal Blair, Committee Member en_US
dc.contributor.advisor Dr. Elana Leithold, Committee Chair en_US
dc.contributor.advisor Dr. Dean Hesterberg, Committee Member en_US Lloyd, Kristen Helen en_US 2010-04-02T17:58:12Z 2010-04-02T17:58:12Z 2007-12-07 en_US
dc.identifier.other etd-10242007-122356 en_US
dc.description.abstract Research conducted on the Waipaoa and Waiapu Rivers on the North Island of New Zealand has recognized and characterized geomorphologic and geochemical processes responsible for the control and delivery of sediment and associated OC to the adjacent margin. Clay mineral compositions from specimens of bedrock, volcanic soils and tephras, suspended river sediment, and recent marine sediments were studied. Identification of the clay minerals was made chiefly by X-ray (XRD), infrared (FTIR), and selective mineral dissolution analyses. Geochemical analyses included organic carbon (OC) concentrations and stable carbon isotopic compositions. Characteristic clay minerals indicative of bedrock contributions include chlorite and illite. Smectite and kaolinite are also present but in lesser quantities. Soil and tephra mineralogy could not be as easily quantified from x-ray diffraction due to the presence of poorly crystalline minerals (i.e. allophane). FTIR spectrometry proved to be a beneficial tool for the identification of clay minerals in the soil. Allophane and the higher concentration of smectite signify material being derived from the soils and tephra. Suspended sediment samples collected during moderate to high river flows exhibited a mixed clay mineral composition derived from both bedrock and soil. Within the Waiapu River, bedrock contributions appeared to be greater due to gullying being the more dominant geomorphologic process. The Waipaoa River showed soil contributions to be as important as rock contributions. Recent marine sediments off the Waiapu River were similar in composition to the suspended Waiapu River sediment. Spatial variability in clay mineralogy associated with cross shelf transport reveal chlorite increases at the expense of illite off the Waiapu shelf. A downcore study was conducted on the Waipaoa shelf to examine temporal variability. The sediments in the flood layer and below resemble the river suspension, with smectite being the dominant clay mineral. The presence of allophane in the flood layers suggests a greater contribution from the soil and subsequent rapid burial. The mineralogy of the top layer resembles that seen in the Waiapu, with illite being the dominant clay. After the clay mineralogy was established, geochemistry was employed to examine contributions from the sources of particulates being delivered to the margin. However, due to the wide range of results, overlap between characteristic isotopic signatures of the sources prevented the successful application of this method. %OC illustrates the mixing of ancient and modern carbon in the rivers and bulk %OC of the rivers is roughly two times greater than the %OC from the rocks. XRD and FTIR results are consistent with and further confirm the mixing of rock and soil particulates in both margins. 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 organic carbon en_US
dc.subject allophane en_US
dc.subject clay mineralogy en_US
dc.subject New Zealand en_US
dc.subject Waipaoa River en_US
dc.title Clay Mineralogy and Organic Carbon Associations in Two Adjacent Watersheds, New Zealand en_US MS en_US thesis en_US Marine, Earth and Atmospheric Sciences en_US

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