Variation of soil Δδ^(13)C values in Xifeng loess-paleosol sequence and its paleoenvironmental implication

查看全文 作　　者：NING [1,2]Youfeng;LIU [1,3]Weiguo;AN [1]Zhisheng 机构地区：[1]State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710075, China;[2]Graduate School of Chinese Academy of Sciences, Beijing 100039,China;[3]College of Energy and Power Engineering, Xi'an Jiaotong University. Xi'an 710049, China 出　　处：《Chinese Science Bulletin》索引2006年第51卷第11期,共5页 基　　金：This work was supported by the National Natural Science Foundation of China (Grant Nos. 40599422, 40523002 & 40121303) ;the National Key Funds of China (Grant No. 2004CB720200). 摘　　要：The carbon isotopic compositions of soil organic matter (SOM) and total carbonate (TC) in Xifeng loess-paleosol sequence have been studied. The δ 13CSOM values vary from ?23.8‰ to ?20.2‰, which are higher in interglacial than in glacial stages. Contrary to δ 13CSOM values, the δ 13CTC values vary from ?8.5‰ to ?3.6‰ and are lower in interglacial than in glacial stages. The differences (?δ 13C) be- tween the δ 13CSOM and δ 13CTC values vary from 14.1‰ to 19.4‰. Our results from the Xifeng loess- paleosol sequence indicate that the ?δ 13C values represent the ratio of primary carbonate (PC) to secondary carbonate (SC). The ?δ 13C values were high in the loess stages, and the maximal PC-to-SC ratio can reach 6:4. But in the paleosol stages, the ?δ 13C values were low, with a small proportion of PC. The ?δ 13C values in loess-paleosol sequence also indicate the contributions of the dust to the loess sediment in the Chinese Loess Plateau because the dust contains the PC. 关 键 词：黄土 古土壤 有机碳 碳酸盐 碳同位素