Institutional Repository of Xinjiang Institute of Ecology and Geography, CAS
Not a member yet
7341 research outputs found
Sort by
CdTe/CdS/ZnS核壳量子点团聚体的水生生物毒性研究
No full textArtificial nanoparticles, includuing quantum dots, have been highlighted in recent years because of their mechanical properties, reactivity, photoelectric properties, and telex conductivity, which are widely used in pharmacy, materials, biotechnology and environmental protection. A large number of nanoparticles will enter into the environment inevitably, such as atmosphere, aquatic and soil through a variety of ways, which would trigger the awareness about environmental safety and health. And the status would change constantly, for example, from dispersion, agglomeration, sedimentation, to suspension. This paper mainly concerned the toxicity of CdTe/CdS/ZnS Core-Shell-Shell quantum dot aggregates to typical organisms in the aquatic environment, such as biofilms, aglae and zebrafishes. It could be separated into three aspects. First, the adsorption and diffusion process of CdTe/CdS/ZnS Core-Shell-Shell quantum dot aggregates in biofilms and its toxicity to biofilms, mainly using FTIR (Total Internal Reflection Fluorescence), FRAP(Fluorescence Recovery After Photobleaching), and 3D reconstruction. Second, the toxicity of CdTe/CdS/ZnS Core-Shell-Shell quantum dot aggregates on Euglena gracilis, including the morphological changes of algae, cholorophyll fluorescence, pigment synthesis, motility and surface properties of algae under the effect of humic acid and CdTe/CdS/ZnS Core- Shell-Shell quantum dot aggregates. Third, the toxicity of CdTe/CdS/ZnS Core-Shell-Shell quantum dot aggregated to zebrafish in the presence of transparent extracellular polymeric particles, CLSM as the main instrument, and several probes are used as well, such as Phen Green SK (diacetate) and CM-H2DCFDA, to detect the accumulation of quantum dots in2+different tissues and organs of zebrafish, DNA damage, the presence of intracellular Cd2+and Zn and ROS as well. The main conclusions are as follows. (1) C. testoteroni could adsorb aggregates of the CdTe/CdS/ZnS quantum dot ( 1 µm), they could further diffuse into deeper layers of the biofilm and penetrate the 45 µm thick biofilm within 25 min. The amount of accumulated quantum dots in microlayers of the biofilm decreased linearly with depth. FRAP results showed that about 30% fluorescence intensity recovered within 5 min, indicating the mobility of quantum dots in the biofilm. The quantum dots dissolved in the biofilm and would release heavy metals and finally exert toxic effects on the biofilms.(2) CdTe/CdS/ZnS Core-Shell-Shell quantum dot could accumulate in algae, the cellswere transformed from strip to sphere. And cells would lose their athletic ability and reunite together further. The photosynthesis Fv/Fm decreased significantly in a short time, indicating quantum dots affected the physiological activity of photosynthesis. The content of chlorophyll a and carotene in the cells treated by quantum dots decreased, while the cynthesis of chlorophyll b stayed the same. The content of polysaccharide and protein decreased after threatened by quantum dots, and the peaks of carboxyl were slightly increased, which could be caused by the combination of carboxyl groups on the surface of quantum dots and the algae. (3) CdTe/CdS/ZnS Core-Shell-Shell quantum dot aggregates could cause DNA damage to gill and intestines cell of zebrafish, and accumulate in some organs and tissues, such as gills, intestines and muscle. When TEP existed, quantum dots accumulate in above-mentioned organs less. The CdTe/CdS/ZnS Core-Shell-Shell quantum dots could release2+ 2+Cd and Zn in gill and liver cells, which could induce the oxidative stress reactions further, while TEP could remit it. But most of the qutumn dots could be excreted out of bodies withtime
长白山阔叶红松林生态系统水碳通量模拟
No full textThe forest of Northeast China is located in the middle and high latitudes,accounting for more than 30% of the total forest area in China. Broad-leaved Koreanpine forest is the zonal forest vegetation in the eastern part of Northeast China, andthe trend of climate changed warming and dry will cause the eco-climatic suitabilityof broad-leaved Korean pine forest to decline significantly. The broad-leaved Koreanpine forest in Changbai Mountain has continuous and long-term observation databased on eddy covariance technique, which provides data support for the validation ofthe model. Model simulation and site observation provide a way to study the carbonand water fluxes in the broad-leaved Korean pine forest ecosystem.The Biome-BGC model is a widely used biogeochemical cycle model tosimulate the carbon, nitrogen and water storage of vegetation, litter and soil indifferent scales. Data assimilation provides an effective way to integrate the modelsimulation and remote sensing observation, through the integration of remote sensingdata in the run of the model, adjusting the model trajectory to reduce model error andimprove simulation accuracy. Ensemble Kalman filter (EnKF) is a sequentialAssimilation Algorithm for estimating the prediction error covariance using a MonteCarlo ensemble prediction method. This paper uses the EnKF assimilated MODIS leafarea index (LAI) into the Biome-BGC model in growing season to simulate the waterand carbon fluxes in the broad-leaved Korean pine forest in Changbai Mountains. Atthe same time, the simulated snow sublimation and the parameters of the calculationmethod of soil temperature are improved, which can effectively reduce the error of theecological respiration in winter. Based on the measured data of eddy covariance, theeffects of data assimilation and model improvement on the simulation precision ofwater carbon flux in the broad-leaved Korean pine forest in Changbai Mountain wereanalyzed. The results are as follows:(1) As compared with the original model simulated without data assimilation, theimproved Biome-BGC model with the assimilation of the MODIS LAI makes the correlation coefficient between the simulated values and the observed values of thegross ecosystem primary productivity (GPP) increased by 0.06, and reduced thecentered root-mean-square error (RMSE) by 0.48 gC•m-2•d-1, ecosystem respiration(RE) correlation coefficient increased by 0.02, centered root-mean-square error isreduced by 0.20 gC•m-2•d-1; the correlation coefficient of net ecosystem exchange ofcarbon (NEE) is increased by 0.35, centered root-mean-square error decreased by0.50gC•m-2•d-1.(2) The correlation coefficient between the simulated values and the observedvalues of evapotranspiration (ET) increased by 0.05, and the data assimilation andmodel improvement have no significant effect on the central root mean square error ofthe simulated and observed ET.(3) The LAI of the Biome-BGC model seriously deviates from the normal LAIvariation, the trend of MODIS LAI is similar to that of real LAI, which lead to theLAI of assimilation is close to MODIS LAI.The data assimilation based on EnKF algorithm improves the accuracy of thecarbon flux simulation in the broad-leaved Korean pine forest in Changbai Mountains,and has an important influence on the more accurate estimation of the carbon flux inthe regional scale
中国西天山晚古生代以来的剥露作用与浅成低温热液矿床保存的研究
No full text浅成低温热液型的金矿是目前世界上最为重要的金矿床类型之一，具 浅成低温热液型的金矿是目前世界上最为重要的金矿床类型之一，具有储量大、埋藏浅、易开采的特点，并且往往与深部斑岩型矿床具有密切的成因联系，一直以来都是国内外矿床学研究的热点。该类型矿床的就位深度极浅（<2 km），很容易受到后期的构造剥蚀，因此，世界范围内的浅成低温热液矿床多数产出于年轻的岛弧或者陆弧环境，其形成时代多数为中-新生代，中生代之前的矿床可能遭受长期的剥蚀而消失殆尽。然而，中国西天山发育了众多古生代大型、超大型浅成低温热液型的金矿床（如：阿希金矿和京希-伊尔曼德金矿），构成了全球罕见的前中生代浅成低温热液成矿省，其保存机制和保存条件是目前尚未解决的重要科学问题。吐拉苏盆地是中国西天山浅成低温热液矿床的重要聚集地，该盆地与其周缘山体的盆山耦合特征涉及到矿床本身的剥露和埋藏作用，是理解其保存机理的关键。磷灰石裂变径迹测年方法具有较低的封闭温度（~110℃），可以有效揭示浅成低温热液矿床自就位以来的热历史。本研究对中国西天山主要山体（科古琴山、乌孙山、那拉提山和婆罗科努山）和赋矿的盆地（吐拉苏盆地）进行了详细的野外地质调查，并系统采集了样品，采用磷灰石裂变径迹年代学的方法研究山体和盆地的构造抬升-剥蚀历史，揭示它们之间的盆山耦合特征，最终讨论浅成低温热液矿床的保存机制和条件。本研究在中国西天山主要山体（科古琴山、乌孙山、那拉提山和婆罗科努山）共采样 28 件，所测得的磷灰石裂变径迹年龄范围为 47.9±9 Ma~182.3±9.9 Ma，平均围限径迹长度为 9.8±0.5~13.7±0.1 μm。裂变径迹数据分析和热历史模拟结果表明，中国西天山主要经历了四个剥露期次，分别对应了不同的构造事件，晚石炭世-晚二叠世（320-250 Ma），随着古天山洋的闭合，塔里木-中天山和北天山发生碰撞拼合，西天山经历了强烈的剥露作用，导致科古琴山、婆罗科努山、乌孙山和那拉提山均隆起地表；晚三叠世-早白垩世（~230-130 Ma），西天山在该阶段经历了慢速的伸展剥露作用，其动力学来源为东部蒙古-鄂霍茨克海的消减闭合；晚白垩世-古新世（~80-50Ma），由于天山西南部科伊斯坦-德拉弧与欧亚大陆南缘的碰撞，西天山经历了剥露作用，但强烈的山体隆升仅集中在南天山，伊犁-中天山和北天山则发生了慢速剥露或者局部的掀斜作用；晚渐新世-早中新世（~30-20 Ma），新生代以来，印度板块与欧亚大陆的持续挤压导致了西天山强烈的变形，科古琴山、婆罗科努山、乌孙山、那拉提山均经历了快速隆升的阶段。吐拉苏盆地及其周缘山体晚古生代以来的盆山演化为最终探讨中国西天山浅成低温热液矿床的保存机理提供了重要的依据。早石炭世晚期（350-320 Ma），由于同火山断裂（走滑断层和正断层）活动致使盆地经历了沉降的阶段，~2.33 km 厚的沉积物（下石炭统阿恰勒河组）覆盖在大哈拉军山组火山岩之上；二叠纪（300-250 Ma），西天山主要山体快速剥露，为吐拉苏盆地提供丰富的物源，~2.50 km 厚的二叠纪沉积覆盖在下石炭统阿恰勒河组之上，浅成低温热液矿床被覆盖，从而避免被剥蚀；晚三叠世-早白垩世（230-100 Ma），西天山主要山体和吐拉苏盆地都经历了慢速剥露的阶段，大约 1.56 km 厚的物质被剥蚀，仍旧有~3.27 km 厚的物质覆盖在浅成低温热液矿床之上；晚渐新世以来（~35 Ma），吐拉苏盆地及其北侧科古琴山经历了快速剥露作用，覆盖在浅成低温热液矿床之上的沉积物被剥蚀，浅成低温热液矿床被剥露至近地表。造山带内部曾经的埋藏作用是古老（前中生代）浅成低温热液矿床得以保存的先决条件。 有储量大、埋藏浅、易开采的特点，并且往往与深部斑岩型矿床具有密切的成因联系，一直以来都是国内外矿床学研究的热点。该类型矿床的就位深度极浅（<2 km），很容易受到后期的构造剥蚀，因此，世界范围内的浅成低温热液矿床多数产出于年轻的岛弧或者陆弧环境，其形成时代多数为中-新生代，中生代之前的矿床可能遭受长期的剥蚀而消失殆尽。然而，中国西天山发育了众多古生代大型、超大型浅成低温热液型的金矿床（如：阿希金矿和京希-伊尔曼德金矿），构成了全球罕见的前中生代浅成低温热液成矿省，其保存机制和保存条件是目前尚未解决的重要科学问题。吐拉苏盆地是中国西天山浅成低温热液矿床的重要聚集地，该盆地与其周缘山体的盆山耦合特征涉及到矿床本身的剥露和埋藏作用，是理解其保存机理的关键。磷灰石裂变径迹测年方法具有较低的封闭温度（~110℃），可以有效揭示浅成低温热液矿床自就位以来的热历史。本研究对中国西天山主要山体（科古琴山、乌孙山、那拉提山和婆罗科努山）和赋矿的盆地（吐拉苏盆地）进行了详细的野外地质调查，并系统采集了样品，采用磷灰石裂变径迹年代学的方法研究山体和盆地的构造抬升-剥蚀历史，揭示它们之间的盆山耦合特征，最终讨论浅成低温热液矿床的保存机制和条件
新疆西准噶尔萨吾尔增生弧-增生楔及其意义
No full text增生型造山带是近年来国际大地构造学研究前沿。增生型造山带发育大陆侧向生长、地体拼贴、洋底高原俯冲等过程，蕴含了极有价值的大陆动力学演化信息，吸引了国内外学者的广泛关注。新疆北部的西准噶尔地区位于哈萨克斯坦山弯构造两翼弯折接合的部位；这一区域晚古生代发育强烈的构造运动、岩浆活动。因此，西准噶尔晚古生代构造演化的研究对于深入理解板块边缘的拼贴过程和产生的岩浆活动具有重要的意义。为厘定哈萨克斯坦山弯构造北翼成吉思岛弧北侧蛇绿岩带构造属性及其增生过程，本文开展了大比例尺填图等野外构造解析和相应的实验室分析，解剖了萨吾尔岛弧及其对应增生楔的物质组成、就位方式、生成时序等等方面的特征。取得以下主要创新性成果：（一）首次识别出塔尔巴哈台增生杂岩，确定其以 OPS 地层为主的蛇绿混杂岩、构造混杂岩、沉积混杂岩和连续单元为典型组合，发育北倾的叠瓦状逆冲推覆构造系。（二）首次在萨吾尔岛弧南部找到晚石炭世-早二叠世弧岩浆，在新疆西准噶尔北缘建立增生弧模型，成功解释了萨吾尔岛弧岩浆向南迁移现象和弧岩浆不断侵入增生楔现象。（三）揭示了塔尔巴哈台增生杂岩南部和北部分别从属于成吉斯弧和萨吾尔弧，在研究区建立了双向俯冲、增生楔对增生楔碰撞的构造模型，二者之间洋盆闭合不早于晚二叠世。这些创新性成果为理解中亚造山带南部哈萨克斯坦山弯构造形成精细过程，解决其构造格局与闭合时限提供了重要的理论依据，对理解其它造山带增生楔-增生弧的结构与组成具有重要的启示与示范作用
天山山区冰雪变化对水储量及径流影响研究
No full text山区是一个独特的地理单元，以冰川和积雪为主要存在形式的固态水资源储量丰富，是众多大江大河的源地。冰川是气候系统的重要组成部分，冰川和积雪覆盖面积的变化对流域水文过程有重要影响。气候变化加速了中纬度山区的冰川退缩和积雪消融。但冰川和积雪面积的缩减对高寒山区的气温升高存在放大效应。中亚天山平均海拔超过 4000 米，在空间上对气温和降水起到重新分配的作用，并储藏有大面积的冰川和积雪，是中亚地区河流的源地，被称为“中亚水塔”。受全球气候变化的影响，天山山区的冰川一直处于退缩状态，尤其是天山中部区域。同时天山的气象观测点稀少，仅有的站点建站时间短不能满足对整个中亚天山的研究，因此当前对天山的研究主要集中在局部区域。观测资料的缺乏，是当前评估气候变化对该区域水资源影响的主要挑战。缺乏对高亚洲区域的水文机制的认识是评价气候变化对该区域水文水资源影响的主要不确定性因素。本文分析了天山山区气温、降水、积雪、冰川及水储量的变化，探讨了气候变化对天山山区水资源的影响机制，构建了适合于高寒区域径流模拟的水量平衡模型，预估了不同气候变化情景下流域径流的可能变化趋势，为科学辨识气候变化对天山山区水资源的影响机制，以及流域尺度的水资源综合管理具有重要参考价值。主要研究结论归纳如下：（1）近半个世纪以来天山山区的气候变化以暖-湿化趋势为主天山山区气候变化研究是基于 APHRO’s 和 ECWMF ERA 数据集，发现天山山区从 1980s 中期开始升温，到 21 世纪初平均气温已接近 5℃，上升了接近了 1℃；从气温空间变化特征来看，整个天山山区在过去 50 年中以升温为主，大部分区域升温幅度在 0-0.04 ℃/a 之间。天山山区的降水变化表现为天山中、东部降水呈增加趋势，增加速率在 0-1.5 mm/a 之间，而天山西部降水呈减少趋势，最大减少速率在-2- -6 mm/a左右，主要位于伊塞克湖流域。3000 米海拔以上区域随气温的升高降雪以增加趋势为主，而 3000 米海拔以下区域随气温的升高降雪以减少趋势为主。同时，降雪率的季节变化与气温的变化密切相关，除冬季随气温的升高降雪以增加的趋势为主外，其他季节都是以减少的趋势为主。这表明存在一个气温阈值从某种程度上影响并控制了降雪变化。因此，确定降雪率和降雨率转化的温度区间范围对于研究降雪率的变化具有重要意义。（2）山区以冰雪为主体的固态水库处于持续的亏缺状态在全球变暖的影响下，天山山区的冰川处于退缩状态。自 1970s 以来，天山冰川总面积大约减少了 8.5%，但是不同的区域退缩速度不一样：海拔 3000 米以下区域的冰川退缩速率最大，达到了 2.3×103kg/(m2*yr)；3000-4000 米海拔区域的冰川退缩速率次之，大约是 0.6×103kg/(m2*yr)；4000-5000 米海拔区域的冰川退缩速率大约为0.3×103kg/(m2*yr)；而 5000 米以上海拔区域的冰川退缩速率就非常小。同时，冰川的退缩速率与冰川面积呈负相关，面积越小退缩速率越快，说明小型冰川对气候变化的响应更为敏感，面积大的冰川相对稳定，而天山山区 90%以上的冰川属于小型冰川，因此这一研究结果具有重要的指示意义。积雪覆盖面积同样呈减少趋势，2002-2013 年天山山区最大积雪覆盖率呈减少趋势，减少速率为 0.44%/a，而最小积雪覆盖率变化不明显，减少速率为 0.01%/a（相当于-47 km2/a）。2002-2013 年天山山区年内积雪覆盖历时的递减速率大概为-0.2 day/yr，年内积雪覆盖历时从 2002 年的 216 天，到 2013 年 208 天，缩短了 8 天。年内积雪覆盖历时变短，意味着积雪对年内的水文系统的缓冲作用降低，会使天山山区水资源的变率加大。近 30 年来，天山山区的雪水当量有一个较小的递减趋势，递减速率大约为-0.017 m/a，但没有通过 p=0.05 水平下的信度检验。天山西部区域雪水当量以递减趋势为主，天山东部区域雪水当量以增加趋势为主。（3）气候变化是驱动山区水储量减少的主要原因GRACE 重力卫星数据为研究山区水储量的变化提供了数据支撑，研究结果表明，2003-2015 年期间天山山区大部分区域的水储量减少速率小于 1 cm/a。但是，天山山区中部偏东区域表现水储量的急剧减少，减少速率达到 4-8 cm/a。春季水储量为正距平，是因为天山山区整个冬半年固态水资源一直处于积累过程，到春季的时候这种积累达到最大值，因此春季的一直为正距平。同样，夏半年一直处于消融过程，到秋季的时候达到消融的最大值，因此水储量在这个季节表现为负距平。冬季和夏季处于正、负距平的过渡阶段，是因为气温和降水组合的年际差异导致的。气候变化是天山山区水储量变化的主要驱动力。山区变暖导致了山区冰川退缩和积雪消融，进一步驱动山区水储量变化。（4）不同气候排放情景下径流变化差异显著开都河流域、阿克苏河流域以及乌鲁木齐河流域的径流变差系数 Cv 值位于0.1~0.2 之间，这是因为冰川和积雪融水对流域径流变化的调节作用。径流分析以基于水量平衡模型为工具。本文通过将冰川物质平衡因子嵌入到水量平衡模型中，模拟径流变化，结果表明，开都河流域的 Nash 效率系数为 0.76，阿克苏河流域和乌鲁木齐河流域的 Nash 效率系数分别达到了 0.8 和 0.86。因此这一方法提高了水量平衡模型在高寒山区的模拟精度。并结合 IPCC AR5 气候排放情景，预估 2020-2100 年这三个流域的径流变化，模型的预测结果表明，在中低排放情景下径流的变化相对稳定，变化幅度较小，但是在高排放情景下径流的变化幅度较大，特别是在 21 世纪中叶以后呈减少趋势。同时发现，冰川面积越大的流域，在气候变化驱动下径流呈减少趋势发生的时间来的越晚，这是因为冰川对水资源的变化具缓冲作用
基于生态环境功能区划的灌木群落生态服务功能研究——以哈密地区为例
No full text本文以哈密地区典型灌木群落为研究对象，通过野外样方调查，结合 TWINSPAN分类方法对群落进行分类，从各群落的物种组成结构、植物区系特征、物种多样性等方面进行分析，并对各典型灌木群落进行生态服务功能评价，研究成果可为该区植被恢复和生态重建提供科学依据。研究结果表明：（1）50 个样方调查共记录到植物 120 种，隶属于 25 科 79 属，其中以藜科、菊科、禾本科等世界性大科居多。以属的分布类型来看，本区存在 9 个分布类型和 5个变型，以北温带分布、地中海区、西亚至中亚分布以及世界分布为主。（2）应用 TWINSPAN 分类方法将 50 个样方划分为 9 个典型灌木群落类型，其中防沙固沙区中分布有 6 个灌木群落，水源涵养区分布有 1 个灌木群落，地下水源区分布有 1 个灌木群落，水土保持区分布有 2 个灌木群落，与野外植被调查的实际情况来看，分类情况较理想。（3）选用 Simpson 多样性指数、Shannon-Wiener 多样性指数、Pielou 均匀度指数、Simpson 优势度指数、Margalef 丰富度指数来描述 9 个典型灌木群落的物种多样性特征，分析得到研究区灌木群落物种多样性水平与新疆其他地区灌木群落多样性水平相比，哈密地区灌木群落多样性水平中等，物种分布不均匀，群落组成结构较简单。通过对多样性指数随海拔梯度进行分析时，发现 Shannon-Wiener 多样性指数与海拔梯度之间，随海拔上升呈现先下降后增长的趋势，并且在海拔 1200m 处多样性指数最小。（4）应用层次分析法建立典型灌木群落生态服务功能的评价体系，从支持功能、提供功能、调节功能和文化功能 4 个方面选取了 12 个评价因子。利用专家打分法确定各评价因子的权重并且为每个群落进行打分，得出研究区 9 个典型灌木群落生态服务功能等级。白皮锦鸡儿+准噶尔铁线莲-狭穗针茅群落和欧亚圆柏+疏花蔷薇-阿尔泰狗娃花群落生态服务功能较高，等级为Ⅱ级，评价等级最低为膜果麻黄+沙拐枣-白茎盐生草群落和短叶假木贼+裸果木-三芒草群落，评价等级为Ⅲ级的群落占群落总数的百分比最高，为 56%。从总体上看，研究内典型灌木群落生态服务功能处于中等水平
焉耆盆地土壤水盐分布及灌田水盐动态过程模拟
No full textThe Yanqi basin, located in the arid area of Northwest China oasis, includes four county and a number of agricultural farms. The groundwater and surface water resources in the Yanqi basin provide a solid base for the economic development of Southern Xinjiang. In the Yanqi basin, the rainfall is low, the evaporation is large, and the unreasonable irrigation leads to the accumulation of salt on the soil surface. Soil salinization has seriously threatened the sustainable economic development and ecological security of the Yanqi basin.This paper takes Yanqi County thoroughbred field and the Yanqi basin as an example, to study the temporal changes of soil moisture and soil salinity and their spatial variabilities and distributions. This was done by combining field measurement campaign, lab analysis and soil water and salt modelling with Hydrus-1D. The Hydrus-1D model was used to simulate soil moisture and salinity transport for two irrigation scenarios. We get the best irrigation scheme. The main conclusions include: (1) Soil sample analysis shows that sulfate chloride is the main component of the soil salinity in the Yanqi basin.The total salt and Cl-, SO42-, Na+, K+, Ca2+ are positively correlated, the first principal component represents the soil structure and salt composition, and the second principal component represents the pH of the soil.(2) The spatial variability analysis shows that the soil salt content of each layer was more consistent with the Gauss model, and the spatial correlation of surface soil salinity was weak. The spatial variability of surface soil moisture was moderate, and the spatial variability of soil moisture in the other layers was very weak. (3) The soil salinity increases gradually from the west to the east, and gradually increases from the north to the south of Kaidu river. The range of non-salinization increased with the increaseing soil thickness, Soil moisture shows a trend of increasing from the west to the east. (4) The soil salinity concentrates in the boundary of the oasis and in the drainage area. (5) For soil temperature with a film and without a film: at 0~70cm it varies like a cosine function. The soil temperatures of a film is higher than without a film. (6) For soil water content with a film and without a film: at 0~50cm it varies like a cosine function; The soil water content in upper soil layer is greatly affected by root system, at 0~50cm soil salt varies like a cosine function, it is relatively stable at 50~70cm for both with a film and without a film.(7) There is a positive relationship between soil temperature and air temperature, and the influence of atmospheric temperature on soil temperature is weakened with the increase of soil depth. Overall, with the increase of temperature, the water content with a film and without film gradually decreases, and the salt content with a film and without a film decreases. (8) The study area was set up with Hydrus-1D model, then calibrated and validated with the measured soil water and salt of July 1, 2016 to September 9, 2016. In addition, based on the developed irrigation scenarios, the study compared the effects of different irrigation scenarios on the soil moisture and salility, and recommended the suitable irrigation schemem
塔里木沙漠公路防护林带土壤水热盐动态及模型模拟
No full textIn the desert area of Xinjiang, it has a potential to irrigate the shelterbelt using theunderground saline water, however, drought and salt stress could influence the plantgrowth and development. Therefore, understanding of soil water and salt dynamics, as wellas the plant response to the stress is a basis to design the reasonable irrigation schedule.With the field investigation, control experiment and model work together, to analyze thespatial and temporal dynamics of soil heat and salt and the tolerant mechanism of typicaldesert plants under different soil types and water salinities in Taklimakan Desert artificialshelterbelt, HYDRUS-1D is used to simulated soil moisture movement and salt. Mainresults for this study are as follows:The difference of soil water characteristic curve of each soil layer in the test areacorresponds to the difference of physical properties, that is, the features of curve of the soillayer with less content of the slits and clays and the bulk density larger is lower, theopposite is higher. Soil water retention capacity was stronger, which were related to thehigher content of clay particles and the smaller soil bulk density. Two models can be usedto test the soil water characteristic curve fitted, Van Genuchten model has more parameters,the fitting accuracy is higher in low suction less than 1.0×105 Pa, the fitted precision ofGardner model in the suction from 1.0×105 Pa to 15.0×105 Pa is slightly higher, on thewhole, Van Genuchten model fitted effect is better than that of Gardner model.Mean monthly soil temperature under the conditions of different depth of theTaklimakan desert shelterbelt approximate sine curve, and the seasonal alternation effecton temperature in the deeper soil layer is smaller than that of the shallow. The soiltemperature diurnal variation curve of 10~50 cm significantly dynamic than the others, thehighest temperature and the minimum temperature are gradually decline at the beginningof September. The soil temperature was affected by precipitation, 10 cm soil layer has mostsignificant response to rainfall. Compared with the sunny day, there is a significantdifference with change process, but the other layer features of the soil temperature is not obvious difference with sunny days, rainfall directly influenced the daily variationcharacteristics of shallow soil temperature.the soil temperature was basically consistent under different plant types, and the airtemperature was significantly correlated with soil temperature (p<0.01). Meanwhile, thecorrelation of soil temperatures in different soil layers decreased as the soil depth increased.In the soil of artificial shelterbelt, the dynamics of soil water and salt displayed an obviousperiodic rule. With respect to Haloxylon ammodendron, the distribution of soil water andsalt displayed a single-peak curve with the peak appeared at 30 cm in soil depth, while thedistribution of soil water and salt to Calligonum mongolicum showed a single-peak curvewith the peak occurred at 10 cm in soil depth. In the 0~200 cm soil profiles, the soilmoisture is divided into active layer, weak layer, and stable layer in Haloxylonammodendron, but active layer and weak layer in Calligonum mongolicum. The soilwetting front was a semi-ellipsoid shape after drip irrigation. The affected depth ofirrigation water was 0.6 m in Haloxylon ammodendron, while 1.5 m in Calligonummongolicum. The soil salt was concentrated in the upper layer. However, soil salinizationdid not exist due to less than 1.0 mS/cm. The growing season of soil pondage is 116.34 mmin Haloxylon ammodendron, but 100.99 mm in Calligonum mongolicum. All the soil waterdeficit ullage reached more than 270 mm. The plant types had few influences on soiltemperature. The irrigation of Calligonum mongolicum should be properly increased formaintaining the health of shelterbelt system.Hydrus-1D model was used to simulate the dynamics of soil water, heat and salt, thesimulated values of soil water, heat and salt transport were obtained, which can basicallyreflect the time variation law of growing season soil water heat salt. Among them, thewhole simulation of soil temperature in the process of simulation effect is better, the soilmoisture is the second, and the soil salt movement simulation effect is relatively poor. ingeneral, the simulated values can reflect the dynamic changes of soil water and salt indifferent soil layers. Our study is beneficial to provide a suitable irrigation system andapproach, which can ensure the sustainable development of shelterbelt system in Taklimakan Desert
天山东部雪岭云杉和西伯利亚落叶松径向生长对气候变化的响应
No full textIn this study, tree-ring cores (Picea schrenkiana and Larix sibirica) were obtainedfrom three sites, ranging from the upper and lower forest border in the eastern section ofthe Tianshan Mountains, northwestern China. The RES chronologies for three sites wereapplied in the study. Response relationship between RES chronologies and monthlyprecipitation, average temperature, season indicators were analyzed using the data fromBalikun meteorological stations. The primary results are: (1) The sensitivity of two tree species to climate changes with altitude was decreased,correlation coefficient (R1, R2), signal-to-noise ratio (SNR), express population signal(EPS) and the percentage variance of the first eigenvalue (PC1) were firstly decreased andthen increased with increasing altitude. The significant positive correlations in the original,low-frequency and high-frequency domain between two tree species on the same altitude,while the chronologies of low and high have few common variations. The correlationbetween HM2Y and average temperature and precipitation is weakened. (2) The results show that between 1957-1984 and 1985-2013, tree ring widths in thedifferent altitude behaved a different response to the change of mode to environmentalfactors under changing climate. At the higher elevations, there was a stronger influence ofclimate on tree growth in Picea schrenkiana during the period 1985-2013 with increasingtemperature than during 1957-1984 with decreasing temperature. The negative response ofthe lower altitude chronology (HM3Y) to the temperature is enhanced and the positiveresponse to precipitation is enhanced. (3) The relationship between Larix sibirica radial growth and climatic factors indifferent elevations also changed between 1957-1984 and 1985-2013. The correlationbetween the low altitude (HM3L) chronology and the climatic factors at two periods issignificantly different. After rapid warming (1985), the relationship between the radialgrowth of Larix sibirica and the temperature and precipitation was significantly reduced.At 2430m a.s.l., the tree growth did not show any significant relationship with precipitationand temperature during 1957-1984, but it was found to be significantly correlated with climate factor during 1985–2013. The high temperature (HM1L) chronology has asignificant negative correlation with the three temperature indices in December last year,and the positive response to precipitation is enhanced. (4) The response of Picea schrenkiana and Larix sibirica at different altitudes toclimate factors are quite different. On the upper limits site (2700m a.s.l.) in TianshanMountains, radial growth of Picea schrenkiana was positively correlated with precipitationof previous July and current October, and positively correlated with temperature of currentApril, June and July. However, the tree-ring width of Larix sibirica was positivelycorrelated with the precipitation in March. On the mid-elevation sites (2430m a.s.l.), radialgrowth of Picea schrenkiana was negatively to temperature of previous August. In contrast,Tree-ring growth of Larix sibirica was positively correlated with temperature in currentJuly and August. On the lower limits site (2160m a.s.l.), tree growth of Picea schrenkianawas mainly controlled by drought and high temperature. However, tree-width of Larixsibirica was mainly controlled by high temperature in June of the current year as well as bythe lack of water in December of the preceding year and January of the current year. (5) Redundancy analysis between six chronologies and climate factors showed thesimilar results as that of the correlation analysis. Therefore, the development trend of warmclimate is conducive to the growth of trees at high-altitude. However, drought stress on thegrowth of trees at the altitude and low altitude may be intensified
塔里木河流域人工与天然绿洲转化过程与适宜比例研究
No full textIn the Tarim River Basin, rapid development of social economy had lead to huge expansion of artificial oases and continuous shrinking of natural oases. It is of great scientific and practical significance to ensure the ecological safety and social prosperity and stability of oasis by realizing the coordinated and sustainable development of natural and artificial oases. According to the different Topographic and Geomorphic conditions and the main factors restricting oasis development, and combined with field investigation, this study divided the nine source stream and the main stream of the Tarim River Basin into three distribution patterns. Three typical river basins were chosen to analyze the artificial oasis expansion and natural oasis shrinking process in the last 20 years. Based on the principle of water balance, the quantitative relationship between artificial and natural oasis transformation and the disappearance and decline area of natural vegetation after 1 × 108 m3 water was consumed by artificial oasis. The suitable area proportion of the artificial and natural oasis of different oasis distribution patterns was put forward. This study provides theoretical support and scientific basis for the comprehensive management of the Tarim River Basin. The main conclusions are stated as follows:(1) Nine sources streams and main stream were divided into inland river desert area pattern, alluvial-proluvial fan pattern and main stream pattern. The Hotan River Basin, Keriya River Basin and Qarqan River Basin belong to inland river desert area pattern; the Weigan-Kuche River Basin, Dina River Basin, Kaidu-Kongque River Basin and Aksu River Basin belong to alluvial-proluvial fan pattern; the middle reach of the Tarim River, Yarkant River Basin and Kashgar River Basin belong to main stream pattern.(2)The total oasis areas of the representative river basins had no clear change, but the area proportion of artificial and natural oasis increased. The area proportions of artificial and natural oasis in the Weigan-Kuche River Basin were 3:7, 5:5 and 6:4 in 1990, 2000 and 2010 respectively. The area proportion of artificial and natural oasis in the Keriya River Basin was 3:7 in both 1990 and 2000, and in 2010 the proportion increased to 4:6. The area proportions of artificial and natural oasis in the Yarkant River Basin were 4:6, 5:5 and 6:4 in 1990, 2000 and 2010 respectively.(3) Cultivated land expansion not only lead to the gradual exsciccation of natural vegetation, but also lead to a larger area of natural vegetation decline. The area proportions of cultivated land expansion and declining and dying Populus euphratica are 1:3.6 and 1:32.7, respectively. (4) The appropriate artificial and natural oases area proportioning of inland river desert area pattern should be between 3:7 to 4:6. The appropriate artificial and natural oases area proportioning of alluvial-proluvial fan pattern should be between 4:6 to 5:5. The appropriate artificial and natural oases area proportioning of main stream pattern should be strictly controlled not more than 4:6