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Paleoenvironmental implications of Holocene long-chain n-alkanes on the northern Bering Sea Slope

Acta Oceanologica Sinica 2017年第8期36卷 137-145页

作者： ZHANG Haifeng WANG Rujian XIAO Wenshen Laboratory of Marine Ecosystem and Biogeochemistry State Oceanic Administration State Key Laboratory of Marine Geology Tongji University

The records of high-resolution terrestrial biological markers （biomarkers） from Core B2-9 from the northern Bering Sea Slope over the last 9.6 ka BP were presented in the study. Variations in input of terrestrial long-chain n-alkanes （referred to as n-alkanes） and vegetation structure in their source regions were investigated. The results show that the nCz7 is the main carbon peak and has the greatest contribution rate of the total n-alkane content; this might be related to the abundance of woody plants and their spatial distribution in the source region, nC23 is another n-alkane having a relatively high content; this was mainly derived from submerged plants widespread along the coastal areas in the northern hemisphere. Total n-alkane content dropped quickly at ca. 7.8 ka BP, ca. 6.7 ka BP and ca. 5.4 ka BP, and was followed by four relatively stable stages mostly controlled by sea-level rise, climate change and vegetation distribution in the source region. Variation in carbon preference index （CPI） indicates that the n-alkanes primarily originated from higher land plants, and the average chain length （ACL） and nCa1/nC27 ratio reveal the relatively stable presence of woody/herbaceous plants during the Holocene, and dominate woody plants in most of the time. Simultaneous variation in total n-alkane content, nC27 content and its contribution, CPI, ACL and nC31/nC27 ratio over several short periods suggest that the growth rate of the woody plant n-alkane contribution was lower than that of herbaceous plants and fossil n-alkanes under the particular climatic conditions of the source region.

关键词： Bering Sea terrestrial input long-chain n-alkanes vegetation structure Holocene

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Warm pool hydrological and terrestrial variability near southern Papua New Guinea over the last 50 ka

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地球环境学报 2011年第1期 324-324页

作者： SHIAU Liang-Jian Institute of Applied Geosciences National Taiwan Ocean University

Abrupt climate changes such as Dansgaard-Oeschger（D-O） cycles and Heinrich events（HEs） are prevalent during the last glacial cycle and widely documented in Northern Hemisphere（NH） high latitudes.However,in tropical regions and the Southern Hemisphere（SH） far fewer records exist,especially in the western Pacific warm pool（WPWP） area.Here,we present a 50 ka archive of Uk sea surface temperature（SST）,planktonic foraminifera oxygen isotopes,and terrestrial input indicators including branched isoprenoid tetraether（BIT） biomarkers,;Th activity,and non-biogenic sediment components recorded in core MD052928 from the WPWP（near southern Papua New Guinea,PNG）.The planktonic foraminifer oxygen isotopes in the core show millennial-scale changes indicating fresher seawater during the NH cold periods（i.e.Heinrich Events,HEs） and suggesting hydrological changes that are most likely linked to the strength of the boreal winter Asian-Australian monsoon（AAM）.Our observations are corroborated by evidence from the same core that indicates increased terrestrial input caused by higher precipitation on land and more river runoff from southern PNG during the cold periods.Consistent with other nearby hydrological records from land,our study indicates persistent millennial-scale hydrological changes within the past 50 ka in the western tropical Pacific and Southeast Asia.The timing of the millennial-scale changes appears to have been determined by the latitudinal displacement of the Intertropical Convergence Zone（ITCZ） that reflects a history of heat transport from the tropics and WPWP.

关键词： sea surface temperature terrestrial input Papua New Guinea Intertropical Convergence Zone

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