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| 1 | Carbon isotopic composition of modern soil and paleosol as a response to vegetation change on the Chinese Loess Plateau显示文摘The relationship between the carbon isotopic composition of paleosols and paleovegetation on the Loess Plateau is still unclear. One of the main reasons is that we are short of knowledge about the characteristics of the carbon isotopic composition of modern soil in this area. A preliminary investigation of the carbon isotopic compositions of the modern soil and the loess/paleosol sequence on the Loess Plateau shows that the carbon isotopic composition of modern soil is consistent with the distribution of modern plants on the Loess Plateau, where the ecosystem is dominated by a mixture of C4 and C3 plants. Comparing theδ13C values of modern soil and loess-paleosol sequences from the Xunyi profile, we conclude that C3 plants dominated the landscape during loess sediment stages, while C4 plants expanded during paleosol stages. | LIU Weiguo NING Youfeng AN Zhisheng WU Zhenghai LU Huayu CAO Yunning | 2005 | Science China Earth Sciences2005，48，1： | 24 |
| 2 | Chinese stalagmite paleoclimate researches: A review and perspective显示文摘Stalagmite is one kind of secondary carbonates formed in limestone caves(speleothem). After cave water droplets containing Ca2+and HCO3 drip onto floor, carbonate in the water might become supersaturated due to CO2 degassing under certain conditions, resulting in the formation of stalagmite in a process year after year. Stalagmite is one of important geological archives for paleoclimate research. The advantages include wide spatial distribution, suitable for U-Th and U-Pb dating, enriched in climate proxies, continuity, long time span, comparability and lower sampling cost etc. These factors have propelled stalagmite paleoclimate research to the forefront of global paleoclimatology with an irreplaceable role. The stalagmite paleoclimate study started in the western countries, mainly in Europe and America in 1960 s–1970 s, while the relevant research in China was progressively developed in the 1980 s–1990 s after the Reform and Opening up. Although there was a huge gap between the overall research level in China and western countries, a solid research foundation, as well as a number of talent teams were established during the period. In the 21 st century, starting from the publication of stalagmite records from Hulu Cave in Nanjing in 2001, the stalagmite paleoclimate research in China has ushered in a flourishing development and a real leap on the basis of international cooperation, resulting in significant international impacts. The landmark achievements, including establishment of the world’s longest(640000 years) East Asian monsoon stalagmite record, as well as the longest Indian monsoon(280000 years),South American monsoon(250000 years), North American westerly climate(330000 years), Central Asian westerly climate(135000 years), and northwestern China westerly climate(500000 years), have laid a milestone in the paleoclimate study in these climate domains. Importantly, these stalagmite records have revealed the relationship of Asian monsoon variations with solar insolation climate change in polar regions, and the South American monsoon changes on orbital-suborbital timescales, which have provided new geological observations for the development of orbital-suborbital climate theory;elaborated coupling and differentiation relationships between the Asian monsoon and the westerly climate;reconstructed the history of Asian monsoon changes in the Holocene in detail, and thus the hydrological and climate variances behind Chinese and Indian civilizationcultural evolutions. Furthermore, a large number of high-resolution stalagmite records over the past 2000 years have been reconstructed, which are important for understanding short-term climate variability and magnitude, events, cycles, and thus the future climate projection. The achievements have also involved the improvements of a number of important techniques, such as U-Th dating method, the establishments of various hydroclimatic proxies, as well as the contributions to the reconstruction of the atmosphere14C variation history over the past ~54000 years. On the perspective of the future, the Chinese stalagmite community should continue to develop key techniques, further clarify the hydroclimatic significance of stalagmite proxies, impel the integration of related disciplines, and concentrate on key scientific issues in global climate change and major social demands. | Hai CHENG Haiwei ZHANG Jingyao ZHAO Hanying LI Youfeng NING Gayatri KATHAYAT | 2019 | Science China Earth Sciences2019，62，10： | 17 |
| 3 | Variation of soil Δδ^(13)C values in Xifeng loess-paleosol sequence and its paleoenvironmental implication显示文摘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. | NING Youfeng LIU Weiguo AN Zhisheng | 2006 | Chinese Science Bulletin2006，51，11： | 6 |
| 4 | An annually laminated stalagmite from the eastern Qinghai-Tibetan Plateau provides evidence of climate instability during the early MIS5e in the Asian summer monsoon显示文摘The Marine Isotope Stage(MIS5e)is characterized by a warmer climate than that of the pre-industrial period,and serves as an analog for the Current Warm Period(CWP).However,uncertainties persist regarding its climatic stability.Here,we retrieved a stalagmite(WXB075)from Wanxiang Cave in the eastern Qinghai-Tibetan Plateau,and employed abs-olute^(230)Th dating and relative annual layer data to establish a high-precision chronological framework for reconstructing the history of the Asian summer monsoon(ASM)and environmental evolution during early MIS5e with multiple proxies.The findings indicate that the annually laminated stalagmite was formed during Cooling Event 27(C27).The deposition of WXB075 experienced a hiatus(~125.58 ka BP)due to a significant cooling event in the North Atlantic,which may be linked to the unstable climate in the Northern Hemisphere.Additionally,the impact of meltwater discharge in high northern latitudes results in a two-phase evolution of the ASM,i.e.,an initial weaker stage followed by a gradual increase(with exception of deposition hiatus).The climatic instability of ASM is generally characterized by a quasi-60 year cycle that affects vegetation conditions,biological productivity,and karst hydroclimate dynamics.However,the increase in meltwater and decrease in temperature in the Northern Hemisphere have led to a weakened ASM and subsequent reduction in precipitation.Consequently,vegetation degradation above the cave has occurred along with a slowdown of karst hydroclimate.The vegetation conditions,organic matter content,and wet/drought of the karst hydroclimate were affected by both the large-scale monsoon circulation and local environment during extreme weakening(strengthening)of the monsoon when high-frequency climatic events of ASM occurred.A comparison ofδ^(18)O records between early MIS5e and the past 2000 years reveals that the climate during early MIS5e differed significantly from that of CWP,Medieval Warm Period(MWP),and Dark Age Cold Period(DACP)but was similar to Little Ice Age(LIA).Comparison with other geological records from the Northern Hemisphere indicates that climate instability was a widespread phenomenon during MIS5e.The power spectrum analysis of WXB075δ^(18)O reveals significant quasi-60 and 35 a cycles during the early MIS5e,which is consistent with the Atlantic Multidecadal Oscillation(AMO).The comprehensive results demonstrate that the ASM in the early MIS5e was closely linked to solar activity,Intertropical Convergence Zone(ITCZ)position,and Atlantic Meridional Overturning Circulation(AMOC). | Tao GAO Pingzhong ZHANG Hai CHENG Leilei ZHANG Xinhu LI Hongyu SHI Wei JIA Youfeng NING Hanying LI R.Lawrence EDWARDS | 2023 | Science China Earth Sciences2023，66，5： | 0 |
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