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Influence of the impounding process of the Three Gorges Reservoir up to water level 172.5m on water eutrophication in the xiangxi Bay

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Science china(Technological sciences) 2010年第4期53卷 1114-1125页

作者： YANG ZhengJian1,LIU DeFu1,JI DaoBin1,2 & xiAO ShangBin1,3 1 College of Civil & Hydroelectric Engineering,china Three Gorges University,Yichang 443002,china 2 School of Water Resources & Hydropower Engineering,Wuhan University,Wuhan 430072,china 3 institute of earth environment,chinese academy of sciences,xi’an 710075,china 1. College of Civil & Hydroelectric Engineering China Three Gorges University Yichang 443002 China2. School of Water Resources & Hydropower Engineering Wuhan University Wuhan 430072 China3. Institute of Earth Environment Chinese Academy of Sciences Xi’an 710075 China

The water level of the Three Gorges Reservoir(TGR) rose to 172.5 m in two stages from September to November,*** hydrodynamic parameters and water quality parameters(*** velocity,temperature,turbidity and nutrient content) had been continuously monitored to reveal the influence of the impounding process of the TGR on the water eutrophication in the xiangxi Bay(XXB).The maximal daily rise of the water level of the TGR was about 2.38 *** water exchange between the mainstream(the Changjiang River) and the XXB of the TGR was enhanced by density current,and its main characteristics were a density-stratified flow in different *** water exchange reduced the differences of the water quality parameters(for example,temperature,turbidity,nutrient level,pH,etc.) between the mainstream and the XXB during the impounding ***,the water stability index in the mainstream remained small but it was lowered in the *** main causes included the dilution by water of lower concentration of the chlorophyll a(Chl.a) entering from the mainstream,the decline of the water stability,and the increase of suspended silt,which induced the Chl.a to decrease in the XXB during the impounding *** grade of the water eutrophication changed from middle eutrophic level to mesotrophic state in the ***,as available nutrients were imported into the XXB from the mainstream during the impounding process the risk of water eutrophication increases in the XXB in the future.

关键词： impounding density current eutrophication the xiangxi Bay the Three Gorges Reservoir

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Distributions of fatty acids in a stalagmite related to paleoclimate change at Qingjiang in Hubei,southern china

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Science china earth sciences 2005年第9期48卷 1463-1469页

作者： xiE Shucheng1,HUANG Junhua1,WANG Hongmei2,YI Yi1,HU Chaoyong1, CAI Yanjun3 & CHENG Hai4 1. Faculty of earth Science,china University of Geosciences,Wuhan 430074,china 2. School of environmental Studies,china University of Geosciences,Wuhan 430074,china 3. SKLLQG,institute of earth environment,chinese academy of sciences,xi’an 710075,china 4. Department of Geology and Geophysics,University of Minnesota,MN55455,USA 1. Faculty of earth Science China University of Geosciences 430074 Wuhan China 2. School of environmental Studies China University of Geosciences 430074 Wuhan China 3. SKLLQG Institute of Earth Environment Chinese Academy of Sciences 710075 Xi’an China 4. Department of Geology and Geophysics University of Minnesota 55455 MN USA

Fatty acids extracted from a subtropical stalagmite at Qingjiang in Southern china’s Hubei Province were analysed using gas chromatography-mass spectrometry. These n-alkanoic acids range from C14 to C26 in carbon number, maximizing at C16, with a second dominance at C22. In contrast to the stalagmite analysed, the overlying soils are characterized by the dominance of heavy-molecular-weight homologues (>C20). The n-fatty acids in the stalagmite were proposed to be contributed by both the soil ecosystems and the microbes harboring in the percolating water and the cave. The ratios of unsaturated to saturated n-fatty acids (C16:1i/C16:0, C18:1/C18:0) appear to show trends comparable with the oxygen isotope records of the stalagmite carbonate, with enhanced values associated with the cold episode such as Heinrich event 1. This paleoclimate-dependent record of the n-fatty acids might reflect microbial changes in physiology and activity in response to the temperature. This record shows somewhat difference from the previous paleoclimate signal extracted from n-alkanols and n-alkan-2-ones of the same stalagmite. The acid record fails to document the well-known Younger Dryas event which was effectively shown by the latter two biomarkers derived from soil ecosystems. This discrepancy might result from the changing biogeochemical impact on different lipid fractions as well as the varied organism populations in different ecosystems.

关键词： biomarker, ecosystem, microbe, speleothem, paleoclimate, Quaternary.

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Structural stability of C60 films under the bombardment of 1.95 GeV Kr ions

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Science Bulletin 2010年第31期 3532-3536页

作者： YAO CunFeng1,2,FU YunChong3,JIN YunFan1*,WANG ZhiGuang1,ZANG Hang1,2,WEI KongFang1,GOU Jie1,MA YiZhun1,2 & SHEN TieLong1,2 1 institute of Modern Physics,chinese academy of sciences,Lanzhou 730000,china 2 Graduate University of chinese academy of sciences,Beijing 100049,china 3 institute of earth environment,chinese academy of sciences,xi'an 710075,china

The structural stability of C60 films under the bombardment of 1.95 GeV Kr ions is *** irradiated C60 films were analyzed by Fourier Transform Infrared(FTIR) spectroscopy and Raman scattering *** analytical results indicate that the irradiation induced a decrease of icosahedral symmetry of C60 molecule and damage of C60 films;different vibration modes of C60 molecule have different irradiation sensitivities;the mean efficient damage radius obtained from experimental data is about 1.47 nm,which is in good agreement with thermal spike model prediction.

关键词： 1.95 GeV Kr ions C60 films structural stability efficient damage radius thermal spike model

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A Prediction Model of Peasants’ Income in china Based on BP Neural Network

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Asian Agricultural Research 2011年第4期3卷 88-90,94页

作者： GUO Qing-chun1,HE Zhen-fang2,LI Li3,KONG Ling-jun1,ZHANG xiao-yong1,KOU Li-qun1 1.Shaanxi Radio &TV University,xi’an 710068,china 2.Cold and Arid Regions environmental and Engineering Research institute,chinese academy of sciences,Lan’zhou 730000,china 3.institute of earth environment,chinese academy of sciences,xi’an 710075,china Shaanxi Radio & TV University Cold and Arid Regions environmental and Engineering Research institute Chinese Academy of Sciences institute of earth environment Chinese Academy of Sciences

According to the related data affecting the peasants’ income in china in the years 1978-2008,a total of 13 indices are selected,such as agricultural population,output value of primary industry,and rural *** on the standardized method and BP neural network method,the peasants’ income and the artificial neural network model are established and *** show that the simulation value agrees well with the real value;the neural network model with improved BP algorithm has high prediction accuracy,rapid convergence rate and good generalization ***,suggestions are put forward to increase the peasants’ income,such as promoting the process of urbanization,developing small and medium-sized enterprises in rural areas,encouraging intensive operation,and strengthening the rural infrastructure and agricultural science and technology input.

关键词： BP Neural Network Peasants’ income Forecast china

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Magnetic properties of Jiaxian red clay sequences from northern chinese Loess Plateau and its paleoclimatic significance

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Science china earth sciences 2005年第8期48卷 1234-1245页

作者： QIANG xiaoke, AN Zhisheng, LI Huamei, CHANG Hong & SONG Yougui 1. SKLLQG, institute of earth environment, chinese academy of sciences, xi’an 710075, china 2. Guangzhou institute of Geochemistry, chinese academy of sciences, Guangzhou 510640, china 1. chinese academy of sciences SKLLQG Institute of Earth Environment 710075 Xi’an China 2. chinese academy of sciences Guangzhou Institute of Geochemistry 510640 Guangzhou China

Detailed rock magnetism investigation of the Jiaxian red clay sequences indicated that there are common magnetic mineralogy properties in red clay and loess-paleosol sequences from the chinese Loess Plateau as well as the marked properties of themselves, magnetic min-erals mainly with magnetite, maghemite, hematite, and possibly limonite/goethite contributing to the magnetic behavior. Meanwhile, it is found that the strong paleosol in red clay sequences has a lower coercivity and higher content of ultra-fine ferrimagnetic grains than that of the weak pa-leosol, which is similar to loess and paleosol in upper Wucheng Loess sequences, and indicates that humid conditions and relatively strong pedogenesis play a significant role in the increase of ultra-fine magnetic minerals and transformation of the magnetic minerals. This suggests that, like Quaternary loess-paleosols, the change of characteristics of paleoclimatic conditions of the late Tertiary red clay deposits is fluctuant. In addition, the results of magnetic hysteresis properties show that the applied saturated field for samples from the Jiaxian red clay sequences is higher than that of the samples from eastern and southern chinese Loess Plateau. It is obviously shown that there exist more hard magnetic minerals and relatively weak biochemical processes in the Jiaxian red clay sequences on northern chinese Loess Plateau. We conclude that the paleocli-matic environment is different between northern and eastern/southern chinese Loess Plateau, and it should be more arid in northern chinese Loess Plateau.

关键词： northern chinese Loess Plateau, red clay, magnetic property, paleoclimatic significance.

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Grain-size features of a Miocene loess-soil sequence at Qinan: Implications on its origin

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Science china earth sciences 2006年第7期49卷 731-738页

作者： QIAO Yansong1,3, GUO Zhengtang2,1, HAO Qingzhen1, YIN Qiuzhen1, YUAN Baoyin1 & LIU Tungsheng1 1. institute of Geology and Geophysics, chinese academy of sciences, Beijing 100029, china 2. institute of earth environment, chinese academy of sciences, xi’an 710075, china 3. institute of Geomechanics, chinese academy of Geological sciences, Beijing 100081, china 1. institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China 3. institute of Geomechanics Chinese Academy of Geological Sciences Beijing 100081 China 2. institute of earth environment Chinese Academy of Sciences Xi’an 710075 China

In this study, grain-size of 507 bulk samples from the QA-I Mioceneloess-soil sequence at Qinan were analyzed, and the grain-size features are compared with those oftypical Quaternary loess and soil samples, representative lacustrine and fluvial samples. Theresults indicate that the grain-size distribution pattern of the Miocene loess is essentiallysimilar to that of Quaternary loess, but greatly differs from the lacustrine and fluvial *** layers are regularly coarser than soil layers, indicating cyclical climate changes. Mediangrain-size along the 253.1 m sequence varies from 6 to 13 μm and the > 63 μm fraction representsonly 5.3% in maximum, 0.9% in average. Long-term grain-size variations are consistent with the loessaccumulation rate at Qinan and with the eolian mass accumulation rate in the North Pacific. Thesefeatures firmly indicate an eolian origin of the studied sequence, and also reveal a coeval changesbetween the long-term changes of eolian grain-size and continental aridity in the dust sourceregions.

关键词： Qinan, Miocene loess-soil sequence, grain-size, eolian origin.

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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 710075 China Graduate University of chinese academy of sciences Beijing 100049 China Key Laboratory of Cenozoic Geology and environment Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 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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environmental characteristics of Mid-Holocene recorded by lacustrine sediments from Lake Daihai, north environment sensitive zone, china

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Science china earth sciences 2006年第9期49卷 968-981页

作者： SUN Qianli1,2, ZHOU Jie1, SHEN Ji3, CHEN Peng1,2, WU Feng1,2 & xiE xiuping1,2 1. State Key Lab of Loess and Quaternary Geology, institute of earth environment, chinese academy of sciences, xi’an 710075, china 2. Graduate University of chinese academy of sciences, Beijing 100039, china 3. Nanjing institute of Geography and Limnology, chinese academy of sciences, Nanjing 210008, china 1. State Key Lab of Loess and Quaternary Geology Institute of Earth Environment Chinese Academy of Sciences Xi’an 710075 China 2. Graduate University of chinese academy of sciences Beijing 100039 China 3. Nanjing institute of Geography and Limnology Chinese Academy of Sciences Nanjing 210008 China

Climate proxies, such as total organic carbon and nitrogen (TOC, TN), carbonate content (CaCO3), grain-size and pollen of the sediment core retrieved from enclosed Lake Daihai which lies in the north china environment sensitive zone are analyzed to reconstruct the environment evolution of the area based on high-resolution radiocarbon chronology. The results reveal that the TOC and TN contents of the sediments correlate well with pollen percentage and pollen flux variations during the Holocene, and both reach their peak values simultaneously at 6.7―3.5 ka BP (calendar age, 7.6―3.6 ka BP). Since 6.7 ka BP, both the CaCO3 and organic matter contents of the core have simultaneous variations, and their high values also occur during 6.7―3.5 ka BP. While during 9.0―6.7 ka BP (calendar age, 10―7.6 ka BP) relatively lower level of organic matter content and pollen flux corre- spond to the higher level of carbonate content. The above relations suggest that during 6.7―3.5 ka BP, the productivity and effective precipitation were greatly improved in the lake drainage area, and this would probably strengthen the hydrodynamic conditions, enhancing organic matter, pollen and carbonate inputs from terrestrial sources. Such processes would account for the enrichment of both organic matter and carbonate in the sediments. While during 9.0―6.7 ka BP, the lower level of or- ganic matter, pollen flux but high carbonate content show depressed productivity and declined vege- tation coverage. The higher carbonate content at this stage would have probably resulted from the higher evaporation ratio of the lake water under relatively drier climate conditions. Therefore, it is in- ferred that during 6.7―3.5 ka BP, the climate was more humid with abundant rainfalls and vegetation was more flourishing in the Lake Daihai area. This can be seen as Holocene Climate Optimum (HCO). As a result, this has evident discrepancies with the traditional notion that the HCO occurs at Early Holocene or early Mid

关键词： Lake Daihai, Mid-Holocene, lacustrine sediments, environmental characteristics.

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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 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

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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 710075 China Graduate University of the chinese academy of sciences Beijing 100049 China College of Resources and Env

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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