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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

Uncertainties in assessing the effect of climate change on agriculture using model simulation and uncertainty processing methods

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chinese science Bulletin 2011年第8期56卷 729-737页

作者： YAO FengMei QIN PengCheng zhang JiaHua LIN ErDa BOKEN Vijendra college of earth science Graduate University of Chinese Academy of Sciences Beijing 100049 China Center for earth Observation and Digital earth Chinese Academy of Sciences Beijing 100094 China chinese academy of Meteorological sciences Beijing 100081 China School of Geoscience Yangtze University Jingzhou 434025 China Institute of Environment and Sustainable Development in Agriculture Chinese Academy of Agricultural Sciences Beijing 100081 China Department of Geography and earth science University of Nebraska at Kearney Kearney NE 68849 USA

Model simulation is an important way to study the effects of climate change on *** assessment is subject to a range of uncertainties because of either incomplete knowledge or model technical uncertainties,impeding effective decision-making to climate *** the basis of uncertainties in the impact assessment at different levels,this article systematically summarizes the sources and propagation of uncertainty in the assessment of the effect of climate change on agriculture in terms of the climate projection,the assessment process,and the crop models linking to climate ***,techniques and methods focusing on different levels and sources of uncertainty and uncertainty propagation are introduced,and shortcomings and insufficiencies in uncertainty processing are pointed ***,in terms of how to accurately assess the effect of climate change on agriculture,improvements to further decrease potential uncertainty are suggested.

关键词：不确定性模型影响评估气候变化农业影响模型模拟不确定性传播气候预测气候模型

Land cover changes based on plant successions: Deforestation, rehabilitation and degeneration of forest in the upper Dadu River watershed

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science china.earth sciences 2005年第12期48卷 2214-2230页

作者： YAN Jianzhong1,2,3, zhang Yili1, BAI Wanqi1, LIU Yanhua4, BAO Weikai5, LIU Linshan1, 2 & ZHENG Du1 1. Institute of Geographic sciences and Natural Resources Research, chinese academy of sciences, beijing 100101, china.2. graduate School of the chinese academy of sciences, beijing 100039, china.3. college of Resources and Environment, Southwest Agricultural university, Chongqing 400716, china.4. The Ministry of science and Technology, P. C. china. beijing 100862, china.5. Chengdu Institute of Biology, chinese academy of sciences, Chengdu 610041, china Institute of Geographic sciences and Natural Resources Research Chinese Academy of Sciences Beijing China graduate School of the chinese academy of sciences Beijing China college of Resources and Environment Southwest Agricultural University Chongqing China The Ministry of science and Technology P. C. China Beijing China Chengdu Institute of Biology Chinese Academy of Sciences Chengdu China

To link regional land use/cover changes with environmental effects, land cover changes are required to reflect vegetation successions, whereas the land cover classification systems commonly used nowadays cannot serve this purpose. In this paper, a new land cover classification system is established in which land covers are classified by the vegetation succes-sions, taking Zamtang County, Barkam County and Jinchuan County in the upper Dadu River watershed as a study area. Using multi-temporal remote sensing images, the land cover data of 1967, 1986 and 2000 are obtained by means of integration of unsupervised classification and visual interpretation methods. The database facilitates the study of land use/cover changes, en-vironmental effects and ecological construction. Land cover changes reflect the main ecological processes in the upper Dadu River watershed. The landscape composed mainly of grasslands, wildwoods and alpine scrubs in 1967 was changed to that of grasslands, secondary forests, al-pine scrubs, fragmentary wildwoods, artificial forests, secondary scrubs in 2000, meanwhile, the landscape got more fragmentized. The total area of the forests decreased by 9.43%. Study results have shown the process of restoration of logged areas in forest centers. From 1967 to 2000, only 6.86 percents of logged areas were converted to shrubs, meadows or crop-lands, and the rest were converted into artificial forests or secondary forests. So the ecological shelter functions will be restored, stage by stage. Firewood collection, charcoal production and overgrazing are the three major triggers for the extensive degradation of alpine oak forests, Sa-bina tibetica forests and meadows. The arid valley grasslands expanded too. The degradation of vegetation in the southern slopes impairs ecological shelter functions and affects livelihood of local residents, so it is essential to find effective measures for ecological restoration and recon-struction. Field investigations have found

关键词： land use/cover classification, upper Dadu River watershed, vegetation successions, GIS, RS.

Carbon Dioxide Fluxes and Concentrations in a Cotton Field in Northwestern china.Effects of Plastic Mulching and Drip Irrigation

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Pedosphere 2011年第2期21卷 178-185页

作者： LI Zhi-Guo Key Laboratory of Oasis Ecology and Desert Environment Xinjiang Institute of Ecology and Geography Chinese Academy ofSciences Urumqi 830011 (China) graduate university of chinese academy of sciences Beijing 100049 (China) Institute of Soil science Chinese Academy of Sciences Nanjing 210008 (China) earth System science Interdisciplinary Center University of Maryland College Park MD 20740 (USA)

In northwestern china. there has been a change from traditional cultivation system （TC） with no mulching and flood irrigation to a more modern cultivation system （MC） using plastic film mulching with drip irrigation. A field study was conducted to compare soil ＇C02 concentrations and soil surface COs fluxes between TC and MC systems during a cotton growing season. CO2 concentrations in the soil profile were higher in the MC system （3107-9212μL L-1） than in the TC system （1 275-8994 μL L-1） but the rate of CO2 flux was lower in the MC system. Possible reasons for this included decreased gas diffusion and higher soil moisture due to the mulching cover in the MC system, and the consumption of soil CO2 by weathering reactions. Over the whole cotton growing season, accumulated rates of CO2 flux were 300 and 394 g C m-2 for the MC and TC systems, respectively. When agricultural practices were converted from traditional cultivation to a plastic film mulching system, soil CO2 emissions could be reduced by approximately 100 g C m-2 year-1 in agricultural lands in arid and/or semi-arid areas of northern and northwestern china.

关键词： agricultural practice carbon cycle greenhouse gas emission soil respiration weathering reaction

纵向岭谷区“通道-阻隔”作用下气温和降雨的空间分布特征

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山地学报 2007年第2期25卷 169-176页

作者：何云玲张一平中国科学院西双版纳热带植物园中国科学院西双版纳热带植物园云南昆明650223 中国科学院研究生院北京100049 云南大学资源环境与地球科学学院云南昆明650091

通过对纵向岭谷区1960-2000年气象数据资料的统计分析,探讨了纵向岭谷对气温和降雨量的通道阻隔作用。结果表明:纵向岭谷区准南北走向的山岭对西南气流具有较强的阻隔效应,导致西侧区域出现大面积的多雨区域(年降雨量在1 500-2 000 mm左... 详细信息

通过对纵向岭谷区1960-2000年气象数据资料的统计分析,探讨了纵向岭谷对气温和降雨量的通道阻隔作用。结果表明:纵向岭谷区准南北走向的山岭对西南气流具有较强的阻隔效应,导致西侧区域出现大面积的多雨区域(年降雨量在1 500-2 000 mm左右);纵向岭谷区的河谷地带呈现显著的通道效应,表现在南、中部,河谷区域从南向北,呈现暖舌和湿舌分布;而在北部,河谷区域从北向南出现冷舌和少雨区域;因此纵向河谷的通道效应在热力作用上表现为,南部有利于暖空气向北输送,而北部有利于冷空气向南输送;在水湿效应上,南部同样呈现水汽输送通道作用,有利于水汽向北输送;但在北部则由于高大山脉背风坡的雨影或焚风效应,导致河谷区域降雨呈现减少趋势。另外,纵向岭谷对于降雨量分布格局变化的作用较强于气温;雨季,纵向岭谷山间河谷对水汽的“通道”效应明显,造成的年降雨量差值可>200 mm;干季,纵向岭谷对冷空气的屏障“阻隔”效应明显,引起的气温差值最大可达3℃;年平均而言,纵向岭谷对年降雨的“阻隔”作用最为显著,年降雨量差值可>1 000 mm。

关键词：纵向岭谷通道—阻隔效应气温降雨空间分布

A Kinematic Thermal Model for Descending Slabs with Velocity Boundary Layers:A Case Study for the Tonga Subducting Slab

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Acta Geologica Sinica(English Edition) 2011年第1期85卷 211-222页

作者： zhang keliang WEI Dongping college of earth science Graduate University of the Chinese Academy of Sciences Beijing 100049 China

For the purpose of investigating the influence of metastable olivine（MO） phase transformations on both deep seismicity and stagnation of slabs,we constructed a 2-dimensional finite element thermal model for a 120 Ma-old 50°dipping oceanic lithosphere descending at 10 cm/yr with velocity boundary layers,which would mitigate the interference of constant velocity field for the slab. The resulting temperatures show that most of intermediate and deep earthquakes occurring within the Tonga slab are occurring inside the 800℃and 1200℃isotherm,*** elevation of olivine transformation near～410 km and respective persistence of metastable olivine and spinel within the transition zone and beneath 660 km would thus result in bimodal positive,zonal,negative density anomalies,*** results together with the resulting pressure anomalies may reflect the stress pattern of the Tonga slab：（i） slab pull force exerts above a depth of～230 km;（ii） MO existence changes the buoyancy force within the transition zone and facilitates slab stagnation at a depth of 660 km;（iii） as the subducting materials accumulated over 660 km,deepest earthquakes occur due to MO transformation;（iv） a flattened‘slab’ may penetrate into the lower mantle due to the density increment of Sp transformation.

关键词： kinematic thermal model subduction zone velocity boundary layer metastable olivine,double seismic zone finite element method

Correlation between plate age and layer separation of double seismic zones

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earthquake science 2012年第1期25卷 95-101页

作者： keliang zhang and Dongping Wei State Key Laboratory of earthquake Dynamics Institute of GeologyChina Earthquake AdministrationBeijing 100029China Key Laboratory of Computational Geodynamics Chinese Academy of SciencesBeijing 100049China college of earth science Graduate University of Chinese Academy of SciencesBeijing 100049China

Global seismicity catalogs are sufficient for characterizing double seismic zones （DSZs） in subducting slab and facilitate to estimate layer separation without inconsistent uncertainties as local catalogs. Previous studies have shown the correlation between DSZs layer separation and plate age while correlation for those younger than -60 Ma is suspicious. The lacking of DSZs with layer separation less than 10 km further makes it difficult to precisely estimate such correlation. Thus, we incorporate eight DSZs data determined through local seismicity into globally-determined dataset and reexamine such correlation. The best fitting results show that both a linear model and a square root of plate age can mathematically fit the layer separation well. However, it is difficult to distinguish these two models when plate age is greater than -20 Ma since their difference is less than 2 km. However, if extrapolation is possible, both models should provide physical information that DSZs will not form if there is no subducting lithosphere. As a result, the DSZs cannot be produced until the oceanic lithospheric age becomes greater than 0.9 Ma in the square root model while the linear model gives a misleading result. As such the square root model demonstrates the relationship physically better than the linear one, it still needs further test in the future with more available data, nevertheless, our study might also provide evidence for the suggestion that the plate age is a primary control factor of the DSZs geometry as well as the subducting process which disregards any local tectonic stresses.

关键词： double seismic zone layer separation plate age correlation best fitting

Lattice-Preferred orientations of olivine in subducting oceanic lithosphere derived from the observed seismic anisotropies in double seismic zones

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earthquake science 2016年第4期29卷 243-258页

作者： Peng Han Dongping Wei keliang zhang Zhentian Sun Xiaoya Zhou Key Laboratory of Computational Geodynamics Chinese Academy of Sciences Beijing 100049 China college of earth science University of Chinese Academy of Sciences Beijing 100049 China State Key Laboratory of earthquake Dynamics Institute of Geology China Earthquake Administration Beijing 100029China beijing Geotherm Research Institute Beijing 100143 China

Subduction zones can generally be classified into Mariana type and Chilean type depending on plate ages, plate thicknesses, subduction angles, back-arc deformation patterns, etc. The double seismic zones （DSZs） in sub- duction zones are mainly divided into type I and type II which, respectively, correspond to the Mariana type and Chilean type in most cases. Seismic anisotropy is an important parameter characterizing the geophysical fea- tures of the lithosphere, including the subduction zones, and can be described by the two parameters of delay time ~t and fast wave polarization direction ~b. We totally col- lected 524 seismic anisotropy data records from 24 DSZs and analyzed the statistical correlations between seismic anisotropy and the related physical parameters of DSZs. Our statistical analysis demonstrated that the fast wave polarization directions are parallel to the trench strike with no more than 30~ for most type I DSZs, while being nearlyperpendicular to the trench strike for type II DSZs. We also calculated roughly linear correlations that the delay time 6t increases with dip angles but decreases with subduction rates. A linear equation was summarized to describe the strong correlation between DSZ＇s subduction angle DSZ and seismic anisotropy in subduction zones. These results suggest that the anisotropic structure of the subducting lithosphere can be described as a possible equivalent crystal similar to the olivine crystal with three mutually orthogonal polarization axes, of which the longest and the second axes are nearly along the trench-perpendicular and trench-parallel directions, respectively.

关键词： Seismic anisotropy Double seismic zonesSubduction zone processes Plate motions Microstructures

Overview of Submicron Aerosol Characterization in china.Using an Aerodyne High-resolution Aerosol Mass Spectrometer

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Overview of Submicron Aerosol Characterization in China Usin...