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Nitrogen isotopic composition of plant-soil in the loess Plateau and its responding to environmental change

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Chinese Science Bulletin 2009年第2期54卷 272-279页

作者： LIU WeiGuo1,2.& WANG Zheng1,3 1 state key {2. of {2. and quaternary geology, institute of earth Environment, Chinese Academy of Sciences, xi’an 710075, china 2.xi’an Jiaotong University, School of Human Settlement and Civil Engineering, xi’an 710049, china 3 Graduate University of Chinese Academy of Sciences, Beijing 100049, china Chinese Acad Sci Inst Earth Environm State Key Lab Loess and Quaternary Geol Xian 710075 Peoples R China.

The nitrogen isotope of soil is of emerging significance as an indicator of climatic change and biogeochemical cycle of nitrogen in nature systems. In this paper, the nitrogen content and isotopic composition of modern ecosystems from arid and semiarid loess Plateau in northwestern china, including plant roots and surface soil, were determined to investigate trends in δ15N variation of plant roots and soil along a precipitation and temperature gradient in northwestern china under the East Asian Monsoon climate condition. The δ15N values of surface soil from the study area vary from ?1.2. to 5.8‰, but from -5.1‰ to 1.9‰ in the plant roots. Our results indicate that (1) although the isotopic compositions of both plant roots and surface soil change with a similar trend along the climate gradient, the apparent nitrogen difference between plant roots and soil existed, with -δ15N values ranging from 0.3‰ to 7.2. with average of 4.1‰; and (2. mean annual precipitation (MAP) is the dominant factor for isotopic composition of plant-soil nitrogen in the loess Plateau, and the δ15N values are less correlated with MAT; we suggest that nitrogen isotopic composition of soil is a potential tracer for environmental changes.

关键词：氮同位素物理性质化学性质环境论

Planation Surfaces on the Tibet Plateau,china

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Journal of Mountain Science 2008年第4期5卷 310-317页

作者： ZHANG xinbao HE xiubin WANG Yangchun LONG Yi institute of Mountain Hazards and Environment CAS Chengdu 610041 China state key {2. of {2. and quaternary geology Institute of Earth Environment GAS Xi＇an 710075 China Graduate University of the Chinese Academic of Sciences Beijing 100039 China

A planation hypothesis is proposed to explain landform evolution of the Tibet Plateau. A denudation threshold （T）, the maximum potential denudation rate for a certain type of rock, is introduced to explain the combined effects of lithology and tectonics on landform evolution. If the tectonic uplifting rate （U） is equal to or less than the threshold rate （U ≤ T）, the tectonic uplifting and terrain denudation are in dynamic equilibrium, and landforms are in a steady state. The end product should be planation surfaces whether the original landforms are flat plains or deeply dissected mountains. If U 〉 T, uplift and denudation are not able to reach a dynamic equilibrium state. The plateau surface is mostly underlain by soft rocks, such as the Mesozoic epimetamorphic argillites and Tertiary sedimentary rocks, while the mountain ranges comprise hard rocks, such as granite, gneiss and limestone. In soft rock regions, hills are low with a relative relief of mostly less than 100 m and the slopes are gentle at a gradient of 〈2.0. In contrast, hills can maintain steep slopes in hard rock regions. The Tibet Plateau has been under an equilibrium condition between tectonic uplifting and denudation except for the mountain ranges. The plateau might have reached the present altitudes before the {2..

关键词： planation denudation threshold landform evolution Tibet Plateau china

Geomorphologic evidence of phased uplift of the northeastern Qinghai-Tibet Plateau since 14 million years ago

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Science china earth Sciences 2004年第9期47卷 822-833页

作者： LU Huayu1, WANG xiaoyong1, AN Zhisheng1, MIAO xiaodong1, ZHU Rixiang3, MA Haizhou2. LI Zhen4, TAN Hongbing2.& WANG xianyan1 1. state key {2. of {2. and quaternary geology, institute of earth Environment, Chinese Academy of Sciences, xi’an 710075 china 2. Qinghai institute of Salt Lakes, Chinese Academy of Sciences. xining 810008, china 3. institute of geology and Geophysics, Chinese Academy of Sciences, Beijing 10002., china 4. Department of Geography, Qinghai Normal University, xining 810008, china Chinese Acad Sci Inst Earth Environm State Key Lab Loess & Quaternary Geol Xian 710075 Peoples R China Chinese Acad Sci Qinghai Inst Salt Lakes Xining 810008 Peoples R China Chinese Acad Sci Inst Geol & Geophys Beijing 100029 Peoples R China Qinghai Normal Univ Dept Geog Xining 810008 Peoples R China

A typical sequence of fluvial terraces and aeolian deposits overlying these ter- races were multidisciplinary investigated. New evidences for uplift process of the northeastern Qinghai-Tibetan Plateau in the past 14 million years were obtained. At least 11 river terraces along Huangshui, the first-class tributary of Yellow River, at the xining-Huzhu region are identi- fied. While the first one (T1) is classified as an accumulation terrace, the others are all basement river terraces, which consist of the Tertiary sandstone and siltstone bedrock, fluvial gravel and pebbles and the overlying aeolian loess-Red Clay deposit. Samples from the aeolian deposits were examined for paleomagnetic stratigraphic reconstruction (1030 samples), luminescence dating (16 samples), magnetic susceptibility and grain-size distribution (more than 4000 sam- ples). The luminescence dating and stratigraphic correlation suggest that terraces of Tll, T10, T8, T7, T3, T2. T1 were formed at 14, 11.3, 1.55, 1.2. 0.15, 0.07 and 0.01 million years ago, re- spectively. Sedimentological analysis and geomorphological observation indicate that formation and evolution of these terraces were mainly driven by tectonic uplift. Therefore, the terrace se- quence provides an ideal geological record, of the uplift process of the northeastern during the past 14 million years, and the timings of the terraces formation are regarded as the timings of tectonic uplift. The significant uplifting events took place at 14, 11.3, 1.2.and 0.15 mil- lion years ago, respectively. The fluvial incision at the xining-Huzhu region is less than 100 m during a period of ~12.million years in the Miocene era (between the Tll and T9), while the Huangshui River had incised 432.m during the past 1.2.million years (from T7 to the present floodplain). The river incision process clearly demonstrates that accelerated rising of the north- eastern Qinghai-Tibet Plateau during the late Cenozoic, and provides new evidence of previous thoughts

关键词： river terrace, tectonic uplift, loess-Red Clay, the past 14 million years, northeastern Qinghai-Tibet Plateau.

Magnetostratigraphy of Late Cenozoic fossil mammals in the northeastern margin of the Tibetan Plateau

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Science Bulletin 2003年第2期48卷 188-193页

作者： SONG Chunhui1,2.FANG xiaomin 1,2.GAO Junping1, NIE Junsheng1,YAN Maodu1,3,XU xianhai1 & SUN Dong1 1. MOE National laboratory of Western china抯 {2. Systems & College of Resource and Environment,Lanzhou University,Lanzhou 730000,china 2. state key laboratory of loess and quaternary geology ,institute of earth Environment,Chinese Academy of Sciences,xi抋n 710075, china 3. Department of Geological Sciences,University of Michigan,AnnArbor,MI 48109,USA Univ Arizona Steward Observ Tucson AZ 85721 USA MOE National laboratory of Western china\'s {2. Systems & College of Resource and Environment Lanzhou University Lanzhou 730000 China

A number of fossil mammals have been found in the very thick Cenozoic stratigraphy of the Guide Basin in the northeastern margin of the Tibetan *** of these are of great significance in mammal evolution and stratigraphic correla-tion on and around the Tibetan Plateau and North ***,the chronology of these mamals is poorly *** of the mammals will not only place precise age constraints on the mammals,but also provide much inlormation on the related stratigraphy that records the uplift process of the Tibetan *** paleomagnetism of the upper part of the Cenozoic stratigraphy at He'erjia and Lajigai north of Guide County has revealed magnetic chrons that can be correlated to Ganss and 3An *** the section spanning about 3.16.5 Ma and the *** and third layers of fossil mammals at about 5.2.,5.1 and 4.4 Ma,*** of the significant genus Gazella kueitensis and the Chinese elephant Anancus sinensis are firstly constrained at about 5.2. MaBP and 4.4 Ma,*** mammalian evolution and the associated increase in coarse sediments and sedimentation rate may suggest that the northeastern Tibetan Plateau was uplifted rapidly at that time,and the eastern Tibetan Plateau with its neighboring regions was not high enough to stop mammal exchange between the northern and southern sides of the Tibetan Piateau.

关键词： Tibetan Plateau Guide Basin Late Cenozoic stratigra-phy fossil mammals paleomagnetism.

Precipitation Pulses and Soil CO_2.Emission in Desert Shrubland of Artemisia ordosica on the Ordos Plateau of Inner Mongolia,china

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Pedosphere 2009年第6期19卷 799-807页

作者： JIN Zhao DONG Yun-She QI Yu-Chun M. DOMROES institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 （China） state key {2. of {2. and quaternary geology Institute of Earth Environment Chinese Academy of Sciences Xi＇an 710075 （China） institute of Geography Mainz University Mainz 55099 （Germany）

Precipitation is the major driver of ecosystem functions and processes in semiarid and arid regions. In such waterlimited ecosystems, pulsed water inputs directly control the belowground processes through a series of soil drying and rewetting cycles. To investigate the effects of sporadic addition of water on soil CO2.effux, an artificial precipitation event （3 mm） was applied to a desert shrub ecosystem in the Mu Us Sand Land of the Ordos Plateau in china. Soil respiration rate increased 2.8 4.1 times immediately after adding water in the field, and then it returned to background level within 48 h. During the experiment, soil CO2.production was between 2.047.0 and 7 383.0 mg m^-2. In the shrubland, soil respiration responses showed spatial variations, having stronger pulse effects beneath the shrubs than in the interplant spaces. The spatial variation of the soil respiration responses was closely related with the heterogeneity of soil substrate availability. Apart from precipitation, soil organic carbon and total nitrogen pool were also identified as determinants of soil CO2.loss in desert ecosystems.

关键词： desert shrub ecosystem Mu Us sand land soil respiration response water addition

Changes in grain-size and sedimentation rate of the Neogene Red Clay deposits along the Chinese loess Plateau and implications for the palaeowind system

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Science china earth Sciences 2005年第9期 126-136页

作者： WEN Lingjuan, LU Huayu & QIANG xiaoke state key {2. of {2. and quaternary geology, institute of earth Environment, Chinese Academy of Sciences, xi’an 710075, china

The wind system responsible for transporting dust onto the Chinese loess Plateau during the late Miocene and Pliocene is still unknown and recent investigations highlight many controversies. This report aims to investigate spatiotemporal changes in grain-size and sedi- mentation rate of the Neogene Red Clay deposits in north china and to explore palaeoclimatic changes during the late Miocene and Pliocene, in particular the palaeowind system that trans- ported dust. Samples were collected from eight Red Clay sections on the loess Plateau. Meas- urement and analysis show that there is a clear southward decrease in the mean grain-size index and in the coarse particle fraction (>2. μm). At Jiaxian site on the northern loess Plateau, the average mean grain-size is around 2. μm, while at Lantian site in the south, the mean is around 9 μm. The coarse particle fraction >2. μm makes up 2..4% and 5.6%, at the two sites respec- tively. This distinct diversity of grain-size in the aeolian Red Clay deposit between the north and south indicate that the palaeodust was transported mainly by northerly low-level winds. The grain-size variations in the Red Clay deposits can also be divided into three stages (the lower, the middle and the upper interval): grain-size of the lower stage is significantly coarser than that of the middle stage, but finer than that of the upper stage. As a consequence, the intensity of pa- laeowind and desiccation of the dust source region during the late Miocene and Pliocene can be divided into three stages: 6.2.5.4 Ma, 5.4―3.5 Ma and 3.5―2.6 Ma. Strength of the palaeowind during the middle stage (5.4―3.5 Ma) is weaker than that of the previous and subsequent stages and the intensity of palaeowind during the latest stage (3.5―2.6 Ma) is stronger than that of the early time (6.2.5.4 Ma). Variations in the sedimentation rate of the Red Clay deposit can also be divided into three stages: the earlier, the middle and the later interval. The sedimentation rate of

关键词： Red Clay deposit grain size atmospheric circulation the late Miocene and the Pliocene Chinese loess Plateau.

The vegetation and climate change during Neocene and Early quaternary in Jiuxi Basin, china

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Science china earth Sciences 2005年第5期 676-688页

作者： MA Yuzhen 1 , FANG xiaomin 1,2., LI Jijun 1 , WU Fuli 1 & ZHANG Jun 1 1. key laboratory of Western{2.’s {2. Systems and College of Resources and Environment, Lanzhou University, Lanzhou 730000,{2. 2. state key laboratory of loess and quaternary geology, institute of earth Environment, Chinese Academy of Sciences, xi’an 710075, {2.

Sporopollen record in the Laojunmiao Section at Yumen in the Hexi Corridor foreland depression at the northern margin of the Tibetan Plateau revealed that during the period of 13.0―11.15 Ma the ecological environment of the Jiuxi Basin is characterized by steppe vegetation and a semi-moist climate. During 11.16―8.60 Ma prevailed forests of cypress and a still warmer, moister climate; steppe vegetation and dry climate began probably at about 8.6 Ma. Although aridification had been relaxed time and again during 8.40―6.93 Ma (forest-steppe, warm-semi-moist), 6.64―5.67 Ma (open-forest and steppe, warmer-semi-moist) and 5.42.4.96 Ma (steppe, semi-arid), the climate in the region became drier and drier in response to the fre- quent occurrence of aridity during 6.93―6.64 Ma (steppe, semi-arid), 5.67―5.42.Ma (de- sert-steppe, arid), 3.66―3.30 Ma (desert-steppe, arid) and 2.56―2.2. Ma (desert, arid). Perhaps the important findings of our study are the notable expansion of drought-enduring plants during 3.66―3.30 Ma and about 2.56 Ma and the replacement of vegetation by vast arid desert.

关键词： Tibetan Plateau Hexi Corridor sporopollen record ecological environment vegetation evolution aridific-ation.

environmental archaeology of the Dachang region in the Daning Valley,the Three Gorges reservoir region of the Yangtze River,china

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Chinese Science Bulletin 2008年第S1期53卷 140-152页

作者： ZHANG Yun 1 &ZHU Cheng 2.1 state key {2. of Vegetation and {2. Change,institute of Botany,Chinese Academy of Sciences,Beijing 100093, china 2.School of Geographic and Oceanographic Sciences,Nanjing University,Nanjing 2.0093,china 1. state key {2. of Vegetation and {2. Change Institute of Botany Chinese Academy of Sciences Beijing 100093 China 2. School of Geographic and Oceanographic Sciences Nanjing University Nanjing 210093 China

environmental archaeology of archaeological sites on both sides of the Dachang section in the Daning River,the Three Gorges of the Yangtze River,shows that riverbed evolution has a great influence on the distribution of archaeological sites during the prehistorical and historical period,and it restricts human activity and the development of ancient *** investigation,dating data,paleocurrent analysis of 100 gravels on the riverbed and archaeological excavation reveal that the riverbed of the Dachang section developed in the Shuangyantang region during the early stage,after about 30 kaBP it shifted westward gradually and reached the present *** with the westward shift,the focus of ancient culture changed for several *** the Western Zhou Dynasty's period,the east riverbank of the Daning River was the main residential *** the Han Dynasty,along with the westward shift,the living space of ancient people was no longer confined to the east riverbank and the focus of culture moved *** the Zhangjiawan site became the main dwelling *** the late Han Dynasty, the villages were flooded and the ancients had to immigrate to a high *** of the Han and the Jin Dynasties outcropped on the flood plain of the east bank because their surface sediments were eroded by several flood events and the westward shift of the riverbed.

关键词： the Daning River environmental archaeology the Shuangyantang site the Zhangjiawan site tombs of the Han and the Jin Dynasties

A "Yellow Cap" on quaternary Red Clay in Jiujiang,Jiangxi Province

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Pedosphere 1999年第4期9卷 311-318页

作者： HU XUEFENG GONG ZITONG(1state key {2. of {2. and quaternary geology, the Chinese Academy of Sciences, P. O. Box: 17,xi’an 710054 (china))(2.7} of Soil Science, the Chinese Acodemy of Sciences, P. O. Box 82., Nanjing 2.0008 (china)) 中科院地球环境所黄土与第四纪地质国家重点实验室陕西西安 710054 中科院南京土壤所江苏南京 210008

A thin layer of yellow-brown-colored earth was generally found on quaternary red clay in Jiujiang,Jiangxi Province. A typical profile was established. Both particle size distribution and REE (rare earthelements) characteristics of the yellow-brown-colored earth of the profile fully suggested its aeolian origin andclose similarity to Naming xiashu loess. The study also implied aeolian origin of the underlying quaternaryred clap Compared with the red clay, the yellow- brown- colored earth was less weathered because of its lowercontent of free iron and higher mole ratios of SiO2.A12.3 and SiO2.(Fe2.3+A12.3 ) as well as its lessdeveloped chemical microtextures of quartz *** order to study the aged of the two deposits comparatively, the thermoluminescent dating method wasused. As a result, the bottom of the yellow-brown-colored esrth was dated to 6015 ka B. P. and the upperpart of the red clay 38854 ka B. P. It was suggested that the yellow- browm- colored earth was formed inthe Late Pleistocene and was probably the aeolian deposit of the Last Glacial, which corresponded with theMalan loess in the loess Plateau of the northwestern part of china; while the underlying red clay was formedin the Middle Pleistocene.A "yellow cap" on quaternary red clay in Jiujiang implied a great climatic and {12. varistionin the beginning of the Late Pleistocene in the southern pot of china, especially in the middle and lowerreaches of the Yangtze River. The eveal not only halted the rubification, once dominating the region, butalso produced a widespread covering of aeolian deposit, as only occurred in the cold and dry environment.

关键词： aeolian deposits quaternary red clay rubification yellow-brown-colored earth