柴达木盆地那棱格勒河流域表层沉积物中锂的分布特征   总被引：1，自引：1，他引：0       下载免费PDF全文

李雯霞  苗卫良  张西营  秦占杰  李庆宽  都永生 《盐湖研究》2022,30(2):86-98

柴达木盆地四湖区卤水锂资源极为丰富,那棱格勒河是其最重要的补给源,查清那棱格勒河流域表层沉积物中锂的分布和赋存特征对深刻理解卤水锂富集成矿过程具有重要意义。以那棱格勒河流域表层沉积物为研究对象,探讨了其中锂的赋存特征及分布规律。结果表明,研究区表层沉积物以砂和粉砂为主,锂主要赋存在粉砂和黏土粒级沉积物中;黏土矿物组成以伊利石和伊蒙混层为主,高盐度卤水环境有利于黏土矿物形成。元素地球化学分析显示,锂主要赋存在伊蒙混层矿物中,较高含量的K对于Li进入伊利石矿物晶格具有一定的抑制作用,Li和B在地质过程中应具有相似的地球化学行为。  相似文献   

黄河流域县域交通供给格局及其空间适配性     

李涛  崔磊波  李继园  陈慧灵  曹小曙 《地理科学进展》2022,41(11):2030-2043

分析黄河流域交通供给水平特征及其与经济社会发展的空间适配性,对交通资源优化配置、提升交通供需适配性具有重要参考。论文基于黄河流域现状综合交通运输与经济社会基础数据,分析了黄河流域县域交通优势度分异特征,并探讨了交通与县域发展质量的空间适配性。结果表明：黄河流域县域交通优势度有待提升,在人口与GDP方面呈现一定错配特征;高优势度县域集中分布在济南—郑州—西安—兰州通道沿线。黄河流域交通供给均衡性水平高于经济社会差异;样带交通优势度呈现陇海—兰新“一”字型样带>“几”字湾样带>南北纵向“1”字型样带的分布态势,固定资产投资、产业结构、城镇化、经济基础是影响黄河流域县域交通优势度的主要因素。“几”字湾样带和南北纵向“1”字型样带还受到高程、坡度等自然因素的制约;流域40.05%的县域处于初级适配状态,38.78%的县域为交通劣势型,集中在青藏高原、黄土高原沟壑区和内蒙古中西部地区,亟需提升交通设施对该类县域经济社会发展的支撑与保障能力。  相似文献   

Erosions on the southern Tibetan Plateau: Evidence from in-situ cosmogenic nuclides 10Be and 26Al in fluvial sediments     

ZHANG Xiaolong  XU Sheng  CUI Lifeng  ZHANG Maoliang  ZHAO Zhiqi  LIU Congqiang 《地理学报(英文版)》2022,32(2):333-357

Investigating topographic and climatic controls on erosion at variable spatial and temporal scales is essential to our understanding of the topographic evolution of the orogen.In this work,we quantified millennial-scale erosion rates deduced from cosmogenic 10Be and 26Al concentrations in 15 fluvial sediments from the mainstream and major tributaries of the Yarlung Zangbo River draining the southern Tibetan Plateau (TP).The measured ratios of 26Al/10Be range from 6.33 ± 0.29 to 8.96 ± 0.37,suggesting steady-state erosion processes.The resulted erosion rates vary from 20.60 ± 1.79 to 154.00 ± 13.60 m Myr-1,being spatially low in the upstream areas of the Gyaca knickpoint and high in the downstream areas.By examining the relationships between the erosion rate and topographic or climatic indices,we found that both topography and climate play significant roles in the erosion process for basins in the upstream areas of the Gyaca knickpoint.However,topography dominantly controls the erosion processes in the downstream areas of the Gyaca knickpoint,whereas variations in precipitation have only a second-order control.The marginal Himalayas and the Yarlung Zangbo River Basin (YZRB) yielded significantly higher erosion rates than the central plateau,which indicated that the landscape of the central plateau surface is remarkably stable and is being intensively consumed at its boundaries through river headward erosion.In addition,our 10Be erosion rates are comparable to present-day hydrologic erosion rates in most cases,suggesting either weak human activities or long-term steady-state erosion in this area.  相似文献   

Urban land development intensity: New evidence behind economic transition in the Yangtze River Delta,China     

YANG Qingke  WANG Lei  LI Yongle  FAN Yeting  LIU Chao 《地理学报(英文版)》2022,32(12):2453-2474

Over the past 20 years, China has experienced multiple economic transitions characterized by marketization, globalization, decentralization, and urbanization; as a result, urban land development intensity (ULDI) has become a significant issue for sustainable development. As China’s largest globalized urban area, the rapid socio-economic development of the Yangtze River Delta has created a huge demand for urban land. We apply a theoretical framework for a four-dimensional analysis tool to understand the dynamic evolution of the ULDI in the context of economic transition. It reveals that marketization, globalization, decentralization, and urbanization affect the ULDI in the economic transition of Yangtze River Delta. Marketization, especially the continuous improvement of land marketization, optimizes the spatial allocation of land resources and encourages urban land users to improve ULDI. Globalization promotes the rapid growth of economy and population through an increase in foreign direct investment. In the process of decentralization, local governments rely on developing a mode of land finance, resulting in a disordered urban space and low ULDI. Population growth and agglomeration during urbanization stimulates residents’ consumption capacity and promotes economic growth, thus creating a greater demand for urban land. However, a low level of development and utilization restricts the improvement of development intensity. Economic development can improve the level of land-intensive use by promoting the adjustment, optimization, and upgrade of urban industrial structures.  相似文献   

基于遥感影像的黄河内蒙古段冰-水分类研究          下载免费PDF全文

翟涌光  张鑫  冀鸿兰  牟献友  张宝森 《干旱区地理》2022,45(3):763-773

及时获取凌汛期河冰和水体的空间分布特征,对于预测冰凌灾害、提高防凌信息化管理水平有重要意义。遥感技术是当前获取河冰和水体空间分布的最主要手段之一。但是,黄河水体有大量悬浮泥沙,这给基于遥感技术的高精度冰-水分类带来了挑战。以黄河内蒙古段为例,基于Landsat 8 OLI遥感影像数据,在利用归一化积雪指数（NDSI）及河道矢量数据排除无关地物的基础上,对比了近红外波段反射率值、归一化差异水体指数（NDWI）、归一化积雪指数（NDSI）、改进的归一化积雪指数（MNDSI）以及归一化差异未封冻水体指数（NDUWI）在黄河内蒙古段典型河道河冰、水体分类中的表现,计算各指标总体分类精度及Kappa系数并进行阈值稳定性分析。结果表明：在利用NDSI和高清历史影像排除河道外无关地物后,NDUWI在各子段影像中的总体分类精度和Kappa系数均达到90.00%及0.90以上,其河冰、水体最优区分阈值大体分布于阈值中值附近。研究结果可为凌汛期黄河冰凌监测方法的选取以及冰上爆破位置的拟定提供依据。  相似文献   

宁夏河东沙地不同坡度柠条锦鸡儿（Caragana korshinskii）水分利用策略差异          下载免费PDF全文

高阳  韩磊  柳利利  王娜娜  彭苓  周鹏  展秀丽 《干旱区地理》2022,45(4):1212-1223

为探讨全球气候变化背景下多元线性混合模型（IsoSource）和贝叶斯混合模型（MixSIAR）解析宁夏河东沙地柠条锦鸡儿（Caragana korshinskii）水分利用策略差异及适用性,利用氢氧稳定同位素技术,结合直接对比法、IsoSource模型和MixSIAR模型对比分析不同坡度（6°、10°、16°和24°）样地柠条锦鸡儿在生长季不同时期对各潜在水源的利用率,并评估两种模型的植物水分溯源效果。结果表明：柠条锦鸡儿对不同土层深度土壤水的利用存在明显的季节性差异,生长季初期,随着坡度的增大,柠条锦鸡儿对中层土壤水的利用率呈现出先增大后减小的趋势;生长季中期,随坡度增大,柠条锦鸡儿主要水分来源由深层土壤转移至浅层土壤;生长季后期,柠条锦鸡儿主要水分来源随着坡度的增大由浅层土壤转移至深层土壤。基于直接对比法的定性判断结果,IsoSource模型和MixSIAR模型计算坡度6°、10°和16°样地柠条锦鸡儿主要水分来源利用率的适用性均较高;而MixSIAR模型计算坡度24°样地柠条锦鸡儿主要的水分来源以及其贡献率具有更高的可靠性。IsoSource模型更适合解析较小坡度（6°和16°）样地柠条锦鸡儿的水分利用策略;而MixSIAR模型解析较大坡度（10°和24°）样地柠条锦鸡儿水分利用策略的适用性更好。研究结果可为我国干旱区植物水分来源鉴别方法的选择提供科学参考。  相似文献   

黄河宁夏段凌汛期气温变化特征     

陆晓静  苏占胜  谭志强 《干旱气象》2014,(1):120-122,127

利用宁夏1991~2010年20 a凌汛期水文和气温序列资料,研究了宁夏凌汛期特征、凌汛灾害发生主要时段,黄河封河、开河集中期与日平均气温之间的关系。结果表明:宁夏凌汛特征为封开河时序相反,小流量、高水位行洪,受强冷空气影响较大;凌汛灾害主要发生在封河和开河期间;日平均气温正负转化日期与封、开河期有对应关系,宁夏封河集中期在12月20日至1月19日;开河集中日期在2月13~20日。在凌汛关键期结合MODIS遥感数据对凌汛灾害监测防范有一定指导意义。  相似文献   

岷江上游流域环境脆弱性评价   总被引：3，自引：0，他引：3  

杨斌  詹金凤  李茂娇 《国土资源遥感》2014,(4)

以岷江上游流域TM遥感数据和地形数据为主要数据源,结合其他统计相关资料,尝试运用层次分析法(analytic hierarchy process,AHP)对复杂因素构成的脆弱性特征进行层次分解和重新构造,建立多目标要素的综合评价指标体系和模型。选取植被指数变化率、人口密度、地形起伏度、坡度及土壤类型5个要素作为评价指标因子,通过AHP确定各评价指标的权重,在Arc GIS平台下将各指标图层进行叠加分析,得出岷江上游区域环境脆弱性评价图,再根据环境脆弱性指数阈值分级,将研究区环境脆弱度分为5级。结果表明:岷江上游环境脆弱性表现较为强烈,自然因素和人文因素是造成该环境脆弱性的本质原因,该方法为岷江上游流域环境脆弱性模式和生态环境综合评价提供了一种定量分析的思路。  相似文献   

ENVIRONMENTAL CHANGE AND ITS IMPACTS ON HUMAN SETTLF, MENT IN THE CHANGJIANG RIVER DELTA IN NEOLITHIC AGE   总被引：1，自引：0，他引：1  

ZHANGQiang LIUChun-ling ZHUCheng JIANGTong 《中国地理科学(英文版)》2004,14(3):239-244

Dating data, altitude of Neolithic sites, climatic changes from sedimentary records and previous research results were collected and analyzed to detect possible connections between climatic changes and human activities in the Changjiang River Delta in the Neolithic Age. The results indicated that hydrological changes greatly impacted the human activities in the study region. Low-lying geomorphology made the floods and sea level changes become the important factors affecting human activities, especially the altitude change of human settlements. People usually moved to higher places during the periods characterized by high sea level and frequent floods to escape the negative influences from water body expansion, which resulted in cultural hiatus in certain profiles. However, some higher-altitude settlements were not the results of climatic changes but the results of social factors, such as religious ceremony and social status. Therefore, further research will be necessary for the degree and types of impacts of climatic changes on human activities in the study area at that time.  相似文献   

Impacts of uncertain river flow data on rainfall‐runoff model calibration and discharge predictions     

Hilary McMillan  Jim Freer  Florian Pappenberger  Tobias Krueger  Martyn Clark 《水文研究》2010,24(10):1270-1284

In order to quantify total error affecting hydrological models and predictions, we must explicitly recognize errors in input data, model structure, model parameters and validation data. This paper tackles the last of these: errors in discharge measurements used to calibrate a rainfall‐runoff model, caused by stage–discharge rating‐curve uncertainty. This uncertainty may be due to several combined sources, including errors in stage and velocity measurements during individual gaugings, assumptions regarding a particular form of stage–discharge relationship, extrapolation of the stage–discharge relationship beyond the maximum gauging, and cross‐section change due to vegetation growth and/or bed movement. A methodology is presented to systematically assess and quantify the uncertainty in discharge measurements due to all of these sources. For a given stage measurement, a complete PDF of true discharge is estimated. Consequently, new model calibration techniques can be introduced to explicitly account for the discharge error distribution. The method is demonstrated for a gravel‐bed river in New Zealand, where all the above uncertainty sources can be identified, including significant uncertainty in cross‐section form due to scour and re‐deposition of sediment. Results show that rigorous consideration of uncertainty in flow data results in significant improvement of the model's ability to predict the observed flow. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献