Environmental influences over the last 16 ka on compound-specific δ13C variations of leaf wax n-alkanes in the Hani peat deposit from northeast China

Shinya Yamamoto, Kimitaka Kawamura, Osamu Seki, Philip Meyers, Weijian Zhou, Yanhong Zheng

Research output: Contribution to journalArticle (Academic Journal)peer-review

48 Citations (Scopus)

Abstract

Compound-specific carbon isotope ratios (δ13C) of leafwax n-alkanes (C21–C33 odd carbon numbered n-alkanes)
weremeasured in theHani peat sequence fromnortheast China. These datawere comparedwith lipid biomarker
compositions to assess changes in local vegetation and paleoclimate for the last 16 ka. The δ13C values of nalkanes
range between−36.6 and−30.7‰, showing that the compounds originate from C3 plants.Much larger
variations (~5.4‰) in the n-alkane δ13C values than those of atmospheric CO2 during the last 16 ka (b 0.5‰)
indicate that the isotopic values were affected by environmental factors in addition to the postglacial δ13C
variations in the atmospheric reservoir. The stratigraphic records of δ13C reveal decoupled fluctuationsamong the
individual n-alkanes, particularly between 15.5 and 11.4 ka. Synchronous excursions in the δ13C offsets among
individual n-alkanes (Δδ13C) and lipid biomarker paleoplant proxies (Paq, and C23/C31 and C27/C31) from14.9 to
13.2 ka and 12.7 to 11.6 ka suggest that vegetational changes are the most likely causes for the decoupled δ13C
variations. Parallel fluctuations of the δ13C values of terrestrial higher plant-derived C29 and C31 n-alkanes and the
n-alkane average chain-length (ACL) from 11 to 6 ka indicate that the δ13C variations responded to net
evaporation changes. Negative shifts in the n-alkane δ13C values coincidingwith the ACL decreases at 10.5–9.3 ka
and 8.1 ka indicate the short-term onset and fluctuations of the summer monsoon strength in eastern China
during the early Holocene.
Original languageEnglish
Article numberA
Pages (from-to)261-268
Number of pages8
JournalChemical Geology
Volume277
Issue number3-4
Publication statusPublished - Oct 2010

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