气候变化领域集成服务门户(CCPortal): Hydrogen isotope ratios of terrestrial leaf wax n-alkanes from the Tibetan Plateau: Controls on apparent enrichment factors, effect of vapor sources and implication for altimetry

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DOI	10.1016/j.gca.2017.04.035
	Hydrogen isotope ratios of terrestrial leaf wax n-alkanes from the Tibetan Plateau: Controls on apparent enrichment factors, effect of vapor sources and implication for altimetry
	Zhang, Xiaolong; Xu, Baiqing; Guenther, Franziska; Muegler, Ines; Lange, Markus; Zhao, Huabiao; Li, Jiule; Gleixner, Gerd
通讯作者	Gleixner, G (通讯作者)
发表日期	2017
ISSN	0016-7037
EISSN	1872-9533
起始页码	10
结束页码	27
卷号	211
英文摘要	Empirical evidence suggested that the altitudinal dependence of hydrogen isotope ratios of leaf wax n-alkanes (dDwax) can be used to estimate paleoaltitudinal changes. However, the application of delta D-wax-based paleoaltimetry remains difficult, as the impacts of evaporative, transpirative and biosynthetic processes on hydrogen isotope fractionations in changing environments and the influence of likely changing water vapor sources are not well explored. For this study, we sampled stream waters, soils and plant leaves along two transects spanning large gradients of altitude, precipitation amount, vapor source, temperature and vegetation type on the Tibetan Plateau (TP). delta D values of stream water (as an approximation for delta D-p), soil water (delta D-sw) and plant leaf water (delta D-lw) as well as leaf wax n-alkanes were measured in order to quantify isotopic fractionations in the formation of leaf waxes. Most interestingly, we found a strong negative correlation between the evapotranspirative enrichment of leaf water against precipitation (epsilon(lw-p)), which combines the effects of soil evaporation and leaf transpiration, and the biosynthetic hydrogen isotope fractionation (epsilon(wax-lw)), which describes isotopic enrichment between leaf wax and leaf water. The relationship yields a steady apparent isotopic enrichment factor (epsilon(wax-p)) between leaf wax and precipitation, which is independent from climatic parameters and has an average value of -107 +/- 26% for grasses (monocotyledons) and -77 +/- 22% for trees (dicotyledons). Since the terrestrial n-alkanes, especially n-C27 and n-C29, in sediments are derived from trees and grasses, the likely change of the vegetation type in the uplift of mountains can change the isotopic estimates by about +/- 30%, which corresponds to an altitudinal change of +/- 1600 m. We, therefore, suggest that hydrogen isotope ratio of sedimentary n-C-31 alkane, which is mainly derived from grasses might be better proxies to reconstruct paleoaltitudes. Our large dataset of delta D-wax from trees and grasses that aimed to mirror the variability of environmental factors over geological time frames showed the lapse rates were significant, but much smaller than in previous studies. Most importantly our result demonstrated that the lapse rate significantly differed for both transects (p = 0.0068), i. e. 0.87 +/- 0.71%/100 m (R-2 = 0.28, p = 0.2841, n = 6) and 2.28 +/- 0.82%/100 m (R-2 = 0.34, p = 0.0135, n = 17) for Indian monsoon and Westerly dominated areas, respectively. This suggests that different moisture sources might strongly affected the observed lapse rates. In consequences altitude reconstructions are strongly complicated in areas with likely changing air masses like the Tibetan Plateau. (C) 2017 Elsevier Ltd. All rights reserved.
关键词	DELTA-D VALUES STABLE-ISOTOPES ORGANIC-MATTER PLANTS IMPLICATIONS D/H RATIOS WATER PRECIPITATION RECORD FRACTIONATION GRADIENTS
英文关键词	Hydrogen isotope; Isotopic fractionation; n-alkanes; Paleoaltimetry
语种	英语
WOS研究方向	Geochemistry & Geophysics
WOS类目	Geochemistry & Geophysics
WOS记录号	WOS:000405786800002
来源期刊	GEOCHIMICA ET COSMOCHIMICA ACTA
来源机构	中国科学院青藏高原研究所
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/259064
推荐引用方式 GB/T 7714	Zhang, Xiaolong,Xu, Baiqing,Guenther, Franziska,et al. Hydrogen isotope ratios of terrestrial leaf wax n-alkanes from the Tibetan Plateau: Controls on apparent enrichment factors, effect of vapor sources and implication for altimetry[J]. 中国科学院青藏高原研究所,2017,211.
APA	Zhang, Xiaolong.,Xu, Baiqing.,Guenther, Franziska.,Muegler, Ines.,Lange, Markus.,...&Gleixner, Gerd.(2017).Hydrogen isotope ratios of terrestrial leaf wax n-alkanes from the Tibetan Plateau: Controls on apparent enrichment factors, effect of vapor sources and implication for altimetry.GEOCHIMICA ET COSMOCHIMICA ACTA,211.
MLA	Zhang, Xiaolong,et al."Hydrogen isotope ratios of terrestrial leaf wax n-alkanes from the Tibetan Plateau: Controls on apparent enrichment factors, effect of vapor sources and implication for altimetry".GEOCHIMICA ET COSMOCHIMICA ACTA 211(2017).