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Paleoenvironmental Biogeochemical Signal Integrity: How in situ Environmental Degradation and Post-collection Sediment Storage Conditions affect Molecular Compositions and Impact Reconstructions
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| 자료유형 | 학위논문 |
|---|---|
| 서명/저자사항 | Paleoenvironmental Biogeochemical Signal Integrity: How in situ Environmental Degradation and Post-collection Sediment Storage Conditions affect Molecular Compositions and Impact Reconstructions. |
| 개인저자 | Shilling, Andrea M. |
| 단체저자명 | Indiana University. Geological Sciences. |
| 발행사항 | [S.l.]: Indiana University., 2019. |
| 발행사항 | Ann Arbor: ProQuest Dissertations & Theses, 2019. |
| 형태사항 | 180 p. |
| 기본자료 저록 | Dissertations Abstracts International 81-03B. Dissertation Abstract International |
| ISBN | 9781085618410 |
| 학위논문주기 | Thesis (Ph.D.)--Indiana University, 2019. |
| 일반주기 |
Source: Dissertations Abstracts International, Volume: 81-03, Section: B.
Advisor: Brassell, Simon . |
| 이용제한사항 | This item must not be sold to any third party vendors. |
| 요약 | This dissertation contributes to the understanding of biogeochemical proxies as tools for reconstructing paleoenvironments. When compared to well-established proxies (e.g. pollen and macrofossils), biomarkers are a relatively new field, some aspects of which have not been thoroughly explored, such as environmental degradation and sample alteration during storage. This dissertation focuses on the use of biogeochemical proxies preserved in lacustrine sediments from Olduvai Gorge, Tanzania to reconstruct the paleoenvironment encountered by early hominins. Additionally, a two-year study was completed to examine the molecular impact of common sediment storage practices and potential for sample alteration during storage. Two chapters of this dissertation concentrate on the use of biogeochemical proxies preserved within lacustrine sediments from Olduvai Gorge, Tanzania to reconstruct changes in the paleoenvironment over ~50,000 years. Previous studies in this region had examined samples collected from outcrops, which are less suitable for biogeochemical analyses due to weathering and degradation compromising the original record. The core material examined here allowed for more extensive biomarker analyses during a time of considerable environmental change. Within the section of core, there was evidence of degradation that occurred after deposition but prior to collection, indicating that all core samples are not without limitations. This study allowed for the comparison of biogeochemistry records in highly preserved versus poorly preserved core material. Additional biogeochemical analyses on the core section with superior preservation showed the environmental response to precession scale climate changes, indications of increasing aridity, and greater climate variability than previously recorded, which all would have impacted hominin evolution. For most paleoenvironmental proxies, post-collection sample alteration is of minimal concern, however, this is not the case for biomarkers. While it is known that care must be taken to avoid contamination during collection, little consideration is given to sample alteration occurring during storage. Any changes in the molecular composition after collection can obscure the original paleoclimate or paleoenvironmental signal, compromising reconstructions. This chapter examined sediment samples prior to and after two years stored under a variety of conditions, to identify affected biomarkers and the conditions that caused the greatest change over the two-year period. |
| 일반주제명 | Biogeochemistry. Geology. Paleoclimate science. |
| 언어 | 영어 |
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