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Hydrocarbon biomarkers as paleoenvir...

Zhang, Zhaohui.

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Hydrocarbon biomarkers as paleoenvironmental proxies: Recorders of vegetational changes in China during the last glacial to Holocene transition.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Hydrocarbon biomarkers as paleoenvironmental proxies: Recorders of vegetational changes in China during the last glacial to Holocene transition./
Author:	Zhang, Zhaohui.
Description:	200 p.
Notes:	Source: Dissertation Abstracts International, Volume: 64-11, Section: B, page: 5404.
Contained By:	Dissertation Abstracts International64-11B.
Subject:	Biogeochemistry. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoeng/servlet/advanced?query=3114037

Hydrocarbon biomarkers as paleoenvironmental proxies: Recorders of vegetational changes in China during the last glacial to Holocene transition.
Zhang, Zhaohui.

Hydrocarbon biomarkers as paleoenvironmental proxies: Recorders of vegetational changes in China during the last glacial to Holocene transition. - 200 p.

Source: Dissertation Abstracts International, Volume: 64-11, Section: B, page: 5404.

Thesis (Ph.D.)--Dartmouth College, 2003.

It is essential to understand how C4 vs. C3 vegetation changes have responded to the climate variations during the last glacial to the Holocene transition. Despite many previous researches, so far it is still difficult to isolate whether <italic>p</italic>CO2 or one of the other climate parameters alone is the factor mainly responsible for C 3 vs. C4 vegetation changes during the transition.Subjects--Topical Terms:

545717
Biogeochemistry.

Hydrocarbon biomarkers as paleoenvironmental proxies: Recorders of vegetational changes in China during the last glacial to Holocene transition.
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100 1 $a Zhang, Zhaohui. $3 1944838
245 1 0 $a Hydrocarbon biomarkers as paleoenvironmental proxies: Recorders of vegetational changes in China during the last glacial to Holocene transition.
300 $a 200 p.
500 $a Source: Dissertation Abstracts International, Volume: 64-11, Section: B, page: 5404.
500 $a Chair: Meixun Zhao.
502 $a Thesis (Ph.D.)--Dartmouth College, 2003.
520 $a It is essential to understand how C4 vs. C3 vegetation changes have responded to the climate variations during the last glacial to the Holocene transition. Despite many previous researches, so far it is still difficult to isolate whether <italic>p</italic>CO2 or one of the other climate parameters alone is the factor mainly responsible for C 3 vs. C4 vegetation changes during the transition.
520 $a I have conducted a detailed δ<super>13</super>C analysis of <italic> n</italic>-alkanes extracted from lake and loess sediments in China along a broad southeast-northwest transect across the country. Two lakes (Toushe and Tianyang) and two loess deposits (Xunyi and Luochuan) were chosen from the SE and NW end of the transect, respectively. Analysis on one core from Heqing Basin in southwestern monsoon area was also performed. Total lipids were extracted by soxhlet or sonication. <italic>n</italic>-Alkanes were isolated by silica gel column chromatography, measured for concentrations on a GC and confirmed for structure on a GCMS, and then analyzed for the carbon isotope ratios on a GCIRMS.
520 $a During the LGM, the southeast experienced a C4 expansion, presumably due to the increasing aridity and/or lower <italic>p</italic>CO 2, together with a growing-season temperature still high enough to support C4 plant growth. However to its northwest end, the Chinese Loess Plateau witnessed a significant decrease in C4 plant cover because of lower growing-season temperatures, despite lower <italic>p</italic>CO 2 and higher aridity. A growth-season temperature below a turnover point of about 14°C appears to be deleterious for C4 vegetation. By contrast, in the Holocene, C4 plant coverage increased on the CLP as growth-season temperatures rose. However, far to the southeast on the Leizhou Peninsula, the dramatically increased precipitation offset the advantages of increasing temperature, leading to a decrease in C4 coverage.
520 $a The two-dimension model of <italic>p</italic>CO2 and growing-season temperature constructed by Cerling et al. (1997) is not adequate to reconstruct vegetation changes over the continent of China during the LGM to the Holocene transition. I have therefore constructed a three-dimension diagram for predicting C4/C3 dominance of grasses, which contains temperature, aridity (precipitation) and partial pressure of CO2.
590 $a School code: 0059.
650 4 $a Biogeochemistry. $3 545717
650 4 $a Geochemistry. $3 539092
690 $a 0425
690 $a 0996
710 2 0 $a Dartmouth College. $3 1025074
773 0 $t Dissertation Abstracts International $g 64-11B.
790 1 0 $a Zhao, Meixun, $e advisor
790 $a 0059
791 $a Ph.D.
792 $a 2003
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoeng/servlet/advanced?query=3114037