期刊
ORGANIC GEOCHEMISTRY
卷 87, 期 -, 页码 86-95出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.orggeochem.2015.07.012
关键词
Peatland; GDGTs; Holocene climate; Asian summer monsoon; Tibetan Plateau
资金
- Marie Curie International Incoming Fellowship within the 7th European Community Framework Programme
- National Natural Science Foundation of China [41072024, 41372033]
- MOST Special Fund from the State Key Laboratory of Continental Dynamics, Northwest University
- NWO through a Rubicon fellowship
- NERC [lsmsf010001] Funding Source: UKRI
- Biotechnology and Biological Sciences Research Council [1239307] Funding Source: researchfish
- Natural Environment Research Council [lsmsf010001] Funding Source: researchfish
Branched and isoprenoidal glycerol dialkyl glycerol tetraether (GDGT) membrane lipids have been widely used to reconstruct past climate and environmental change. They are not, however, widely applied to peat deposits and the controls on their distributions in peats remain unclear. Here, we present a high resolution record of branched and isoprenoid GDGT concentrations and distributions from a peat core from the Tibetan Plateau that spans the last 13 kyr, a period characterised by distinct dry and wet periods in the region. The lowest concentrations of total branched glycerol dialkyl glycerol tetraethers (brGDGTs) occurred during a presumably dry interval in the mid-Holocene, suggesting that brGDGTs-producing bacteria are less productive under such conditions, perhaps reflecting their putative anaerobic ecology. The mean annual air temperature (MAT) estimates derived from the methylation index of brGDGTs and cyclisation ratio of brGDGTs (MBT'/CBT) are higher than present mean annual temperature in the region and closer to summer temperatures, perhaps due to seasonal production of brGDGTs. The downcore distributions of isoprenoidal and branched GDGTs are dominated by GDGT-0 and brGDGT II, respectively. The high fractional abundances of GDGT-0 in warm and especially wet intervals suggest that these conditions are favourable for some groups of methanogenic archaea. The mid-Holocene dry interval is associated with an increase in the fractional and absolute abundance of crenarchaeol, which could be indicative of enhanced ammonia-oxidising archaeal-mediated nitrogen cycling under these conditions. Taken together, variations of GDGT concentrations in peats appear to document the response of microbial processes to climate change and variations in the biogeochemical environment. (C) 2015 Elsevier Ltd. All rights reserved.
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