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A study on responses of soil erosion and sediment yield to closing cultivation on sloping land in a small catchment using 137Cs technique in the Rolling loess Plateau,china

A study on responses of soil erosion and sediment yield to c...

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中国科学院地质与地球物理研究所2003学术年会

作者： FENG Mingyi~(1,4),D.E.Walling~3,ZHANG xinbao~(1,2) & WEN Anbang~1 1.Chengdu institute of Mountain Hazards and environment,Chinese Academy of Sciences(cas).Chengdu 610041.china 2.state key laboratory of loess and quaternary geology.institute of earth environment,cas,xi’an 710075.china 3.Department of Geography and Archaeology.Exeter University,Exeter EX4 4RJ.UK 4.Sichuan Teachers College.Nanchong 637002.china

By comparison of volumes and Cs contents of the deposited sediments before and after 1993,changes of specific sediment yields and relative sediment contributions from the gully area and from the inter gully area after closing cultivation on the later area on a small catchment of Zhaojia Gully,in the Rolling loess Plateau,are analyzed in this *** cultivation in a large scale has not resulted in decrease but increase of specific sediment yield of the catchment,in sharp decrease of the sediment yield and the relative sediment contribution of the inter-gully area, and in increase of the sediment yield and the contribution of the gully area,for a short *** mean specific sediment yield of 29650 t km a of 1994-1996 in the catchment was 2.2 times the average value of 13413 t km a for a long *** specific sediment yield of the inter-gully area decreased from the 14335 t km a in 1994 to 7034 t km a in 1995 and 3517 t km a in 1996,while the yield of the gully area varied between 44944 and 62136t km a during the period of 1994-1996 which was much greater than the value of 21118 t km a before *** relative sediment contribution from the inter-gully area decreased from 23% in 1994 to 15%in 1995 and 6%in 1996,while the contribution from the gully area increased from 77%in 1994 to 85% in 1995 and 94%in *** is suggested that compacting of ploughed soils resulted in increasing of the erosion resistance but in decreasing of the precipitation infiltration,therefore, the soil erosion reduced but the runoff amount increased on the inter-gully *** of delivering runoff from the inter-gully area to the gully area should result in activeness of gully erosion and mass movements,consequently,in increase of the total sediment yield from the catchment.

关键词： loess Plateau closing cultivation gully ara inter-gully area relative sediment contribution 137Cs

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The microtine distribution and its environmental significance since the Middle Pleistocene in Zhangping Caves of the Qinling Mountains

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Science china earth Sciences 2008年第2期51卷 294-299页

作者： LI Yongxiang1 & XUE xiangXu1,2 1 state key laboratory of Continental Dynamics, Department of geology, Northwest University, institute of Cenozoic geology and environment, xi’an 710069, china 2 institute of earth environment, state key laboratory of loess and quaternary geology, Chinese Academy of Sciences, xi’an 710075, china state key laboratory of Continental Dynamics Department of Geology Northwest University Institute of Cenozoic Geology and Environment Xi’an China institute of earth environment State Key Laboratory of Loess and Quaternary Geology Chinese Academy of Sciences Xi’an China

Three microtine species are recovered from the Zhangping Caves of the Qingling Mountains, namely Microtus oeconomus, Caryomys inez and Caryomys eva. They are climate-sensitive ones with different ecological habits, therefore their distribution well corresponds to environmental variations. Statistical comparison of the distribution of fossil microtines and their counterparts nowadays displays that the climate variation of the studied area and its contiguity since the middle Pleistocene are: warm and humid at 493 ka ago, cool and humid at 259 ka ago―cold and humid at 205 ka ago―cool and humid at 28 ka ago, and warm and dry at present.

关键词： environmental variation since Middle Pleistocene microtine fossils Zhangping Caves of the Qinling Mountains

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Paleoenvironments indicated by the fossil mammalian assemblages from red clay-loess sequence in the Chinese loess Plateau since 8.0 Ma B.P.

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Science china earth Sciences 2006年第5期49卷 518-530页

作者： XUE xiangxu1,2, ZHANG Yunxiang1,2 & YUE Leping1,2 1. state key laboratory of Continent Dynamics (Northwest University), institute of Cenozoic geology and environment, De- partment of geology, Northwest University, xi’an 710069, china 2. institute of earth environment, state key laboratory of loess and quaternary geology, Chinese Academy of Sciences, xi’an 710075, china state key laboratory of Continent Dynamics (Northwest University) Institute of Cenozoic Geology and Environment Department of Geology Northwest University Xi’an China institute of earth environment State Key Laboratory of Loess and Quaternary Geology Chinese Academy of Sciences Xi’an China

Information from eleven profiles of eolian earthy red silty clay and loess of the middle of the Late Miocene to Holocene age have been studied and correlated. A complete summary profile with projected isotopic ages and fossil-bearing beds has been assembled. The profile is subdivided into 12 stratigraphic units proceeding from the lower (older) to the upper (younger) one. The character of mammalian assemblages contained in each unit was analyzed and the corresponding pa- leo-climatic environments were deduced. The environmental character of each period and the change from the middle of the Late Miocene at about 8.0 Ma B.P. up to the Holocene progressed from the hot semiarid and semi-moist, warmer-moist, warm-moister of the Late Miocene. To slightly less warm moist, cool-dry, slight-warmer-moister of the Pliocene; later the cool to cold dry periods alternated frequently with the mild semiarid and semi-moist periods of the quaternary. Vegetation progressed from the grasslands with sparse woods, wooded shrub-grasslands and subtropical forest-grasslands of the Late Miocene age to sparse grasslands and dry grasslands of the Pliocene; and to sparse grasslands, dry grasslands and tundras of the quaternary. The climate changes in the Neogene were of low-amplitute in a generally warm-humid background. Those of the quaternary were of higher am- plitude with a longer phase. Cool or cold dry and slightly warm semiarid and semi-moist climates al- ternated on a generally cool-dry background. The tendency since the start of the quaternary was the change to more northern and western shift in the loess Plateau, with progressively cooler and dryer conditions. The dramatic uplift of the Qinghai-xizang (Tibet) Plateau and the forming and expansion of the Arctic ice sheet might be the main reasons of the more pronounced changes in the quaternary.

关键词： paleoenvironment, mammalian fossils, eolian red clay-loess sequence, loess Plateau.

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Preliminary reconstruction of the desert and sandy land distributions in china since the last interglacial period

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Science china earth Sciences 2004年第Z1期47卷 89-100页

作者： CHEN Huizhong, SU Zhizhu, YANG Ping & DONG Guangrongkey laboratory of Desert and Desertification, Cold and Arid Regions environmental and Engineering Research institute, Chinese Academy of Sciences, Lanzhou 730000, china state key laboratory of loess quaternary geology, institute of earth environment, Chinese Academy of Sciences, xi’an 710075, china institute of loess Plateau, Shanxi University, Taiyuan 030006, china key laboratory of Desert and Desertification Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou China state key laboratory of loess quaternary geology Institute of Earth Environment Chinese Academy of Sciences Xi’an China institute of loess Plateau Shanxi University Taiyuan China

The desert and sandy land are the products of arid climate. The spatial distribution of modern deserts and sandy land in china and their relation to climate show following characteristics: arid and hyper-arid desert zones, at isohyet of less than 200 mm, are dominated by mobile dunes; semi-arid steppe and arid desert steppe with the precipitation between 200?00 mm, are dominated by semi-fixed and fixed sand dunes; the precipitation of sub-humid forest grassland and humid forest zones with scattered fixed sand land is higher than 400 mm. With this as reference, in combination with considerable amount of paleoclimatic data in desert regions and adjacent regions, the distributions of desert and sandy land in china during the last intergla-cial period, the last glacial maximum (LGM), and the Holocene megathermal, were preliminarily reconstructed. The results compared with that of today show that the distribution of desert and sandy land in china was greatly dwindled during last interglacial period, and the mobile dune area was about two-thirds of that of today's, but greatly expanded during LGM. However, the dwindling area of desert and sandy land in the Holocene megathermal was smaller than that in the last interglacial period. The forcing mechanism was mainly related to the changes of East Asian winter and summer monsoon, south-northward swing of the westerlies and the variations of the Qinghai-Tibet Plateau monsoon intensity caused by global climate changes during the cold and warm intervals since the last interglacial period.

关键词： the glacial-interglacial period, desert, sandy land, spatial distribution.

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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 laboratory of loess 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 〈200. 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 quaternary.

关键词： planation denudation threshold landform evolution Tibet Plateau china

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Neogene eolian deposits within the West Qinling Mountains:Climatic and tectonic implications

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Chinese Science Bulletin 2010年第15期55卷 1483-1487页

作者： GE JunYi 1,2 & GUO ZhengTang 3 1 state key laboratory of loess and quaternary geology (SKLLQG),institute of earth environment,Chinese Academy of Sciences,xi’an 710075.china 2 Graduate University of Chinese Academy of Sciences,Beijing 100049,china 3 key laboratory of Cenozoic geology and environment,institute of geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,china state key laboratory of loess and quaternary geology (SKLLQG) Institute of Earth Environment Chinese Academy of Sciences Xi’an China Graduate University of Chinese Academy of Sciences Beijing China key laboratory of Cenozoic geology and environment Institute of Geology and Geophysics Chinese Academy of Sciences Beijing China

The Qinling Mountains constitute a key climate barrier between southern and northern *** recent investigations revealed widely spread eolian deposits of Neogene age mantling the piedmont highlands of the intermountain basins within West ***-mammalian fossils dated a 150.2 m section (NL-VI) near xihe for the late Miocene to Pliocene (～10-4 Ma).Soil micromorphology,grain-size and geochemical analysis consistently define typical loess-soil alternations for the upper (0-66 m) and lower (98-150.2 m) parts of the section,with the middle section (66-98 m) having been affected by episodic slope *** results add important insights to the earlier studies about the widespread eolian deposition in northern china during the Miocene,prior to 8 *** also suggest that the basic configuration of the ridges and inter-ridge basins of West Qinling has already formed by ～10 *** well-preserved eolian deposits are unlikely to support intense substratum deformation and rapid uplift of West Qinling since the late Miocene.

关键词：秦岭山脉风尘堆积构造意义气候新近纪晚中新世地球化学分析风尘沉积

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Boron isotopic fractionation in laboratory inorganic carbonate precipitation:Evidence for the incorpora-tion of B(OH)_3 into carbonate

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Science china earth Sciences 2008年第12期51卷 1776-1785页

作者： xiAO YingKai1,2, LI HuaLing1,3, LIU WeiGuo4, WANG xiuFang1 & JIANG ShaoYong5 1 Qinghai institute of Salt Lakes, Chinese Academy of Sciences, xining 810008, china 2.state key laboratory of environmental Geochemistry, institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, china 3 Nanjing institute of geology and Mineral Resources, Nanjing 210016, china 4 state key laboratory of loess and quaternary geology, institute of earth environment, Chinese Academy of Sciences, xi’an 710075, china 5 state key laboratory for Mineral Deposits Research, Department of earth Sciences, Nanjing University, Nanjing 210093, china Qinghai institute of Salt Lakes Chinese Academy of Sciences Xining China state key laboratory of environmental Geochemistry Institute of Geochemistry Chinese Academy of Sciences Guiyang China Nanjing institute of geology and Mineral Resources Nanjing China state key laboratory of loess and quaternary geology Institute of Earth Environment Chinese Academy of Sciences Xi’an China state key laboratory for Mineral Deposits Research Department of Earth Sciences Nanjing University Nanjing China

A laboratory inorganic carbonate precipitation experiment at high pH of 8.96 to 9.34 was conducted, and the boron isotopic fractionations of the precipitated carbonate were measured. The data show that boron isotopic fractionation factors (αcarb-3) between carbonate and B(OH)3 in seawater range 0.937 and 0.965, with an average value of 0.953. Our results together with those reported by Sanyal and collabo-rators show that the αcarb-3 values between carbonate and B(OH)3 in solution are not constant but are negatively correlated with the pH of seawater. The measured boron isotopic compositions of carbonate precipitation (δ11Bcarb) do not exactly lie on the best-fit theoretical δ 11B4-pH curves and neither do they exactly parallel any theoretical δ 11B4-pH curves. Therefore, it is reasonable to argue that a changeable proportion of B(OH)3 with pH of seawater should also be incorporated into carbonate except for the dominant incorporation of B(OH)4- in carbonate . Hence, in the reconstruction of the paleo-pH of sea-water from boron isotopes in marine biogenic carbonates, the use of theoretical boron isotopic frac-tionation factor (α4-3) between B(OH)4- and B(OH)3 is not suitable. Instead, an empirical equation should be established.

关键词： boron isotopic fractionation biogenic carbonate B(OH)3 incorporation

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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 laboratory of loess 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 state key laboratory of loess and quaternary geology Institute of Earth Environment Chinese Academy of Sciences Xi’an China School of Human Settlement and Civil Engineering Xi’an Jiaotong University Xi’an China Graduate University of Chinese Academy of Sciences Beijing 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

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Constraints of authigenic carbonates on trace elements (Sr,Mg) of lacustrine ostracod shells in paleoenviron-ment reconstruction and its mechanism

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Science china earth Sciences 2008年第5期51卷 654-664页

作者： HU Guang1,2, JIN ZhangDong1 & ZHANG Fei3 1 state key laboratory of loess and quaternary geology, institute of earth environment, Chinese Academy of Sciences, xi’an 710075, china 2 Graduate University of the Chinese Academy of Sciences, Beijing 100049, china 3 College of Resources and environmental Science, Nanjing Agricultural University, Nanjing 210095, china state key laboratory of loess and quaternary geology Institute of Earth Environment Chinese Academy of Sciences Xi’an China Graduate University of the Chinese Academy of Sciences Beijing China College of Resources and environmental Science Nanjing Agricultural University Nanjing China

Molar ratios of Mg/Ca and Sr/Ca were measured in two species of ostracod shells preserved in the upper core (15–55 m) of the Hequing Basin in Yunnan Province, southwest china. By correlating the molar ratios between Mg/Ca and Sr/Ca and comparing them with Sr concentrations of the sediments, we suggested that: (1) the molar Mg/Ca and Sr/Ca ratio variations in respective ostracod primo reflected the changes in its ambient water composition and ecology; (2) the molar Sr/Ca ratios responded better to the salinity change linearly than Mg/Ca without aragonite precipitation in the system, and otherwise there was no linear relation between them; and (3) the molar Sr/Ca ratios were mainly controlled by salinity and authigenic carbonate precipitation, whereas the molar Mg/Ca ratios were related to both salinity and temperature. In fact, the rate of ostracod growth owing to temperature controls the fluctuation of Mg/Ca in shells. Here, more attentions should be paid to the constraint of authigenic mineral precipitation processes on the trace elements in ostracod shells and to the correlation between these trace elements in biogenic carbonates and compositions of the sediments in systems and in future in vitro experiments.

关键词： ostracod shell molar Sr/Ca ratio molar Mg/Ca ratio environmental response Heqing Basin

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Characterization of MASDs of surface soils in north china and its influence on estimating dust emission

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Chinese Science Bulletin 2004年第20期49卷 2169-2176页

作者： MEI Fanmin1,2, ZHANG xiaoye1, LU Huayu1, SHEN Zhenxing1 & WANG Yaqiang1 1. state key laboratory of loess and quaternary geology, institute of earth environment, Chinese Academy of Sciences, xian 710075, china 2. xian University of Engineering Science and Technology, xian 710048, china state key laboratory of loess and quaternary geology Institute of Earth Environment Chinese Academy of Sciences Xi'an 710075 China xi'an University of Engineering Science and Technology Xi'an 710048 China

The micro-aggregated size distribution (MASD) of surface soil is an important parameter for modelling dust emission. However, there is no dataset of MASDs of all sur-face soil types in north china. The MASDs are here pre-sented, measured by dry sieving, for typical surface soil sam-ples, including sandy soil, gravelly sand soil, gravelly loam soil, loam soil and silt loam soil, collected from sandy deserts, Gobi deserts, oases, farmlands in steppe regions and steppe areas in north china. The MASDs of various surface soil types exhibit a combination of several log-normal distribu-tions of five separated sizes with mean mass median diame-ters (MMDs) of 90, 210, 390, 600 and 980 mm, respectively, and mean standard deviations (SDs) of 1.25, 1.40, 1.25, 1.35 and 1.25 respectively. The log-normal distributions corre-spond to very fine sand, fine sand, medium sand, coarse sand and very coarse sand population. On the basis of characteri-zation of the retrieved MASDs of various surface soil types in north china, dust emission fluxes are modelled by a dust production model (DPM model). It is shown that dust emis-sion has been significantly influenced by MASDs. Fine sand and very fine sand are always associated with the highest dust emission fluxes. Emission fluxes of the medium sand, gravelly sand soil, gravelly loam soil and loam soil are lower than those of very fine sand and fine sand, but larger than those of the coarse sand. The differences in dust emission fluxes vary among the different soil types from 101 to 103 mg·m-2·s-1. Dust emission fluxes from sandy deserts and farmlands covered with sand sheets in north china rang from 101 to 104 mg·m-2·s-1 while those from Gobi deserts, farmlands and steppes with gravelly desertification range from 101 to 102 mg·m-2· s-1. The modelled results indicate that deserts and farmlands with sand are the major dust sources in north china.

关键词：华北地区 MASDs 微块状粒度分布地面土壤粉尘排放壤土大气污染气溶胶

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