Hydrogen isotope ratios of terrigenous n-alkanes in lacustrine surface sediment of the Tibetan Plateau record the precipitation signal
Hydrogen isotope ratios of terrigenous n-alkanes in lacustrine surface sediment of the Tibetan Plateau record the precipitation signal
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DOI：
10.2343/geochemj.42.331
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发表时间：
2008-08
影响因子：
0.8
通讯作者：
Zhong-huan Xia;Baiqing Xu;I. Mügler;Guangjian Wu;G. Gleixner;D. Sachse;Liping Zhu
中科院分区：
文献类型：
--
作者：
Zhong-huan Xia;Baiqing Xu;I. Mügler;Guangjian Wu;G. Gleixner;D. Sachse;Liping Zhu
以青藏高原沿着南北向剖面的强永冰川湖、羊卓湖、纳木错湖、克鲁克湖和小柴达木湖为研究对象，测定了其现代湖泊表层沉积物中n-C25 ~ n-C31的氢同位素比值，探讨了这些生物标志物的气候意义。正构烷烃的δD值与大气降水的δD值比较，变化范围为-167‰ ~-51‰，与大气降水的δD值有明显的相关性，表明陆源烷烃记录了大气降水信号。降水对n-C_（25）、n-C_（27）烷烃的分馏作用范围为-45‰ ~-70‰，降水对n-C_（29）、n-C_（31）烷烃的分馏作用范围为-70‰ ~-95‰，二者沿着藏南样带分布较稳定，平均值分别为-57‰和-82‰。通过与欧洲南北样带的-130‰沿着的氢同位素分馏值的比较，表明青藏样带的大气降水和陆地正构烷烃沿着的氢同位素分馏具有明显的特征。
Hydrogen isotope ratios were measured on terrigenous alkanes (n-C25 to n-C31) extracted from recent lake surface sediments from the climatically and environmentally distinct basins Qiangyong Glacier Lake, Yamzho Lake, Nam Co Lake, Keluke Lake and Xiao Qaidam Lake along a S-N transect in the Tibetan Plateau to explore the climatic implication of these biomarkers. δD values of these n-alkanes are compared to that of precipitation spanning a wide range from -167‰ to -51‰ and clearly correlate with δD values of meteoric water, indicating that terrigenous alkanes record the precipitation signal. The fractionation between precipitation and n-C25, n-C27 alkanes cover a range from -45‰ to -70‰ whilst that between precipitation and n-C29, n-C31 alkanes varies from -70‰ to -95‰ both being fairly constant along the S-N Tibetan transect with the mean at -57‰ and -82‰ respectively. By comparison with the fractionation of -130‰ along the S-N European transect, it implies that the hydrogen isotopic fractionation between meteoric water and terrestrial n-alkanes along the Tibetan transect represent distinct character.