1995-2015年全球不同气候带典型冰川补给型湖泊动态变化          下载免费PDF全文

刘吉平  金晶  李晟铭  宋开山 《水科学进展》2021,32(1):1-9

基于1995年、2005年和2015年3期Landsat影像数据,利用遥感和地理信息系统技术,分析全球不同气候带典型冰川补给型湖泊面积、数量及其对气候变化的响应。结果表明:①1995-2015年全球典型冰川补给型湖泊面积增加了2.32%,数量减少了2.26%,其中以小型湖泊（< 1 km2）和大型湖泊（>50 km2）面积变化最为剧烈,中型湖泊（1~50 km2）面积则相对稳定,1995-2005年冰川补给型湖泊面积与数量的变化速率相比2005-2015年较快。②1995-2015年热带、亚热带、温带冰川补给型湖泊面积与数量均在增加,其中以热带冰川补给型湖泊变化最为剧烈,其面积上升了20.62%,数量上升了25.32%,亚寒带与寒带冰川补给型湖泊面积与数量均减少,其中以寒带冰川补给型湖泊变化最为明显,其面积减少了11.3%,数量下降了18.97%。可为全球典型冰川补给型湖泊的变化及其影响因素的后续研究提供依据和参考。  相似文献   

湖泊沉积对地震动的响应特征与古地震序列重建     

李德文  李林林  马保起  张健 《地学前缘》2021,28(2):232-245

湖泊沉积因其对地震动的敏感而被认为是“天然地震仪”,湖泊沉积古地震研究有机会重建长时间尺度的地震(动)序列,对认识区域发震孕震环境和地震复发规律具有潜在优势,是当前古地震学研究的重要方向之一。本文旨在总结现今湖泊沉积古地震研究的主要进展、存在的问题和未来展望。首先通过与传统古地震研究关注的记录对比,扼要介绍了湖泊沉积地震动记录在形成和保存潜力、空间分布以及感应能力等方面的相对优势。然后从过程角度总结了湖泊沉积对地震动响应的主要机制,着重剖析了液化、流化和沉积物再悬浮等不同机制在控制因素、过程特点、响应阈值等方面的异同。再结合湖泊沉积对地震动响应的过程特点和研究现状,总结了不同类型的湖泊沉积地震动记录,对比分析了变形构造、块体运动堆积、浊流堆积和再悬浮沉积等4种类型记录的沉积学和动力学特征;对不同类型记录的古地震学含义和研究手段进行了梳理。再总结了地球物理勘探、结构构造和理化代理指标等现阶段流行的方法在不同尺度湖泊沉积古地震识别和古地震序列重建中的适用性和局限性,后者主要缘于湖泊沉积系统本身的复杂性和外部扰动过程的多样性。最后指出,当前湖泊沉积古地震研究面临的主要问题是缺乏普适性的响应模式、判别依据和甄别准则;今后工作应致力于对湖泊沉积地震动响应过程的深入理解,积极引进数字或试验模拟等理论工具与方法,从二维观察扩展到三维重建;数据解释力求宏观结合微观,由单一指标转向综合性组合式指标,为最终建立普适性的诊断指标和判别依据服务。  相似文献   

陆相坳陷湖盆沉积对深时古气候的响应信号:以准噶尔盆地西北缘安集海河组为例     

王彤  朱筱敏  董艳蕾  杨道庆  苏彬  谈明轩  刘宇  伍炜  张亚雄 《地学前缘》2021,28(1):60-76

“深时”古气候研究范围为前第四纪地质记录,目的在于为未来气候预测提供依据。准噶尔盆地西北缘安集海河组沉积期,研究区处于早古近纪极热气候(PETM)时期,由于其温室气体排放与当前工业废气排放水平相当,对于全球变化以及地球系统科学研究具有重要意义,一直以来都是古近纪气候研究的热点。准噶尔盆地西北缘在早古近纪沉积期发育大范围分布的典型陆相坳陷湖盆沉积,因其远小于海洋的沉积规模而具有远高于海洋系统的气候变化敏感度,能够更加精确地记录古气候演化对湖盆沉积体系的控制作用。本文以准噶尔盆地西北缘安集海河组为主要研究对象,选取28块砂岩样品和23块泥岩样品分别进行粒度分析和微量元素测试。实验结果显示:研究区安集海河组砂岩中值粒径分布在7.58~393 μm,平均值为74.44 μm,属于细砂级别;微量营养元素Ni、Cu和Zn的富集指示高生产力水平,元素Mo、Re、V、Co、Cr组合以及Re/Mo、V/Sc、V/Cr和Ni/Co指示氧化型沉积环境,Sr/Cu指示干燥炎热的气候条件。综合岩心观察和镜下鉴定等手段,针对坳陷湖盆对极热气候事件的响应进行系统分析,从岩石学和生物地球化学两个方面寻找沉积物中的信号记录。在极热气候条件下,研究区整体处于干旱炎热的气候环境,随着干旱进程的不断加剧,湖盆蒸发作用强烈,湖平面下降,沉积物粒度逐渐变粗,沉积物暴露水面遭受氧化,形成大面积展布的陆相红层沉积,同时,水体中CO₂分压不断上升,导致碳酸盐矿物浓度达到过饱和状态,以基底式碳酸盐胶结物的形式析出;受干旱气候加剧的影响,湖水持续浓缩,水体盐度上升,整体表现为陆相半咸水沉积环境,水体氧化性逐渐增强,古生产力水平呈现先增后降的变化趋势。  相似文献   

Progress in Numerical Simulation of Long-Term Impact of Thermokarst Lakes on Permafrost Thermal Regime     

Feng Ling  Tingjun Zhang 《地球科学进展》2018,33(2):115-130

Thermokarst lakes are a major heat source for the adjacent permafrost and a significant source of atmospheric methane. These lakes have important impacts on the physical, chemical, biological, geomorphological and hydrological processes occurring in the ground under and around thermokarst lakes, and seriously affect the local environment and the stability of the structures constructed in permafrost regions. Numerical simulation methods provide an effective method for quantitative analysis of the long-term impact of thermokarst lakes and their evolution on permafrost surrounding the lakes, and have deepened our knowledge about the impact of thermokarst lakes immensely. Summarizing the research progresses in numerical simulation of long-term impact of thermokarst lakes on thermal regime of surrounding permafrost has an important guiding function to improve mathematical models and develop more effective models. In this study, the components, functions, advantages and defects of several typical mathematical models having developed over the past ten years or so were reviewed, such as the heat conduction model with phase change, thaw slumping model, the coupled lake-permafrost model, thaw lake expansion model combining thermal processes with mass wasting and thaw-driven subsidence, the coupled heat conduction and moisture migration model, and the moving mesh method based thermokarst lake dynamic evolution model. Several issues deserving to be paid further attention in the future researches were proposed, including creating more effective models, determining the more realistic initial condition, lucubrating thermal and physical parameters of the typical soils, consider the impact of lake water replenishment, quantitative analysis of the thermal effect of supra-permafrost water flow around the thermokarst lakes, creating the coupled governing equation of heat conduction with phase change and convective heat transfer, embed ding the effect of climate warming in the model, numerical investigation of the long-term influence of thermokarst lake drainage on the environment change in permafrost regions, analyzing the long-term joint impact of multiple lakes on adjacent permafrost, simulating the near-shore talik development process and feature beneath shallow water in expanding thermokarst lakes, and continuing to do the systemic and comprehensive field measurements.  相似文献   

Study on Environmental and Hydrological Effects of Thermokarst Lakes in Permafrost Regions of the Qinghai-Tibet Plateau     

Fujun Niu  Wei Wang  Zhanju Lin  Jing Luo 《地球科学进展》2018,33(4):335-342

Thermokarst lake is the most visible morphologic landscape developing during the process of permafrost degradation, and it is still an international hot topic in permafrost research. The climate warming, and the consequent degradation of the permafrost on the Qinghai-Tibet Plateau aggravate thermokarst lake development. The permafrost is normally considered as an aquiclude, and the permafrost degradation, especially when the permafrost is completely thawed by a thermokarst lake, might influence regional ground water. Therefore, a research program focusing on environmental and hydrological effects of thermokarst lakes in permafrost regions of the Qinghai-Tibet Plateau was started and supported by the National Natural Science Foundation of China. The work proposed by the application includes: To analysis the spatial and temporal distribution rule of thermokarst lakes in the Qinghai-Tibet Engineering Corridor (QTEC) under the climate change and engineering activities, and to evaluate the ecological environment effects through remote sensing and field investigation; to reveal the main factors influencing a typical thermokarst lake and its hydrothermal condition, and to elucidate the conversion relationship between the thermokarst lake and the groundwater with hydrological and isotope tracer tests; to make an analysis of the influences of different lake stage and size on regional permafrost, hydrological conditions and ecological environment through numerical simulation and statistical modelling, considering the relationships between the thermokarst lake and the ground water level. The research results will help to accurately assess regional permafrost ecological environment evolution and trend prediction, and to reasonably understand the impact factors of the permafrost hydrological evolution and its response mechanism to the ecological environment in the river source regions of the Qinghai-Tibet Plateau. In this paper, the research status analysis, the main research contents, research objectives and prospects were introduced so as to provide some references for related researchers and engineers.  相似文献   

基于Fluent数值模拟的冰湖涌浪分析 ——以西藏聂拉木县嘉龙错为例     

阿如汉  涂杰楠  刘红岩  童立强  郭兆成 《冰川冻土》2018,40(4):837-845

冰湖溃决洪水或泥石流（GLOF）是青藏高原主要灾害之一,其形成的灾害链对人民的生命财产安全造成了严重的威胁,其中冰崩导致的冰湖溃决是GLOF的主要灾害形式,但由于其发生位置偏远、间隔时间长、随机性强,导致实地观测资料缺乏,冰崩入湖形成的涌浪机理和过程仍不清晰,而涌浪的规模是GLOF造成下游灾害大小的最主要因素。为分析冰湖涌浪的产生、沿程传播过程和对冰碛坝的爬坡高度,以西藏聂拉木县嘉龙错为例,采用有限体积法,基于流体计算软件Fluent,模拟了嘉龙错补给冰川发生冰崩导致冰湖涌浪的过程。结果表明：数值模拟能较好地对涌浪的产生、规模、沿程传播和对岸爬坡过程进行再现,涌浪初始高度随着冰湖水深、冰体入湖速度和冰体厚度的增加而增大,涌浪高度增加趋势随着冰体入湖速度和冰湖水深的增加而增大,随着冰体厚度的增加而减小。  相似文献   

中国玛珥湖及其研究意义   总被引：4，自引：2，他引：2  

储国强  刘嘉麒 《岩石学报》2018,34(1):4-12

随着全球变化研究的深入,科学家们认识到古气候变化除轨道尺度的冰期/间冰期旋回之外还存在年代际-千年尺度的高频变化和突变事件。要认知这些变化,古气候记录的时间分辨率要达到"年-年代际"。因此,寻求时间跨度长、连续性好、信息丰富的高分辨率记录是过去全球变化研究面临的主要任务之一。玛珥湖为火山射汽喷发形成的封闭湖泊,由于其独特的形成机制及水文背景,使其能够提供数万年乃至几十万年连续稳定的沉积记录,是高分辨率古气候、古环境变化研究的重要对象。中国玛珥湖得天独厚,从热带到寒温带均有分布,为系统研究中国不同气候区各种时间尺度古气候变化规律提供了理想材料。本文基于中国玛珥湖的分布及沉积特征,探讨玛珥湖沉积记录能够为古全球变化研究做出怎样的贡献,解决什么科学问题,具体包括以下三个方面的内容:(1)在轨道尺度上,精确定位现代气候在地质历史中的位置是未来最具挑战性的科学问题之一。我国热带地区玛珥湖沉积物跨越了至少4个冰期-间冰期旋回,能够为理解冰期驱动机制、下一次冰期来临、高低纬关联等关键科学问题提供多学科数据;(2)千年尺度古气候变化,其成因可能源于不同的动力学机制,是气候系统对各种外部和内部驱动因子响应的结果,因此千年震荡可能存在明显的时空差异。集成不同气候带的玛珥湖沉积记录将为理解千年震荡规律及其驱动因子做出贡献;(3)年-年代际气候变化是预测未来气候变化的基础,PAGES、IPCC以及PAGES-Asia 2K均将过去2千年来气候变化作为预测未来几十年至百年尺度上重大全球变化的背景,并为此构建全球数据体系,玛珥湖沉积特别是纹层沉积记录能够填补某些地区高分辨率数据的空白。  相似文献   

The tempo-spatial characteristics and forming mechanism of Lithium-rich brines in China     

《China Geology》2018,1(1):72-83

With the technological development of exploitation and separation, the primary sources of lithium have gradually changed from ore to brine, which has become the main raw material, accounting for more than 80% of the total production. Resources of lithium-bearing brine are abundant in China. This paper has summarized the spatial and temporal distribution, characteristics, and formation mechanism of the lithium-rich brine in China, aiming to provide a comprehensive set of guidelines for future lithium exploitation from brines. Lithium-rich brines usually exist in modern saline lakes and deep underground sedimentary rocks as subsurface brines. The metallogenic epoch of China’s lithium-rich brine spans from the Triassic to the Quaternary, and these brines exhibit obvious regional distribution characteristics. Modern lithium-rich saline lakes are predominately located in the Qinghai-Tibet Plateau. In comparison, the subsurface lithium-rich brines are mainly distributed in the sedimentary basins of Sichuan, Hubei, Jiangxi provinces and so on in south Block of China, and some are in the western part of the Qaidam Basin in Qinghai province in northwestern China. Lithium-rich saline lakes are belonging to chloride-enriched, sulfate-enriched, and carbonate-enriched, while the deep lithium-rich brines are mainly chloride-enriched in classification. On the whole, the value of Mg/Li in deep brine is generally lower than that of brine in saline lakes. The genesis of lithium-rich brines in China is not uniform, generally there are two processes, which are respectively suitable for salt lakes and deep brine.  相似文献   

Remote sensing of nutrients in a subtropical African reservoir: testing utility of Landsat 8     

Mhosisi Masocha  Chipo Mungenge  Tamuka Nhiwatiwa 《国际地球制图》2018,33(5):458-469

Remote sensing is useful for water quality assessments but current remote sensing applications favour parameters that are easy to detect such as chlorophyll-a. An assessment of the utility of Landsat 8 for detecting nutrients was conducted in Mazvikadei reservoir in Zimbabwe. The main objective was to determine whether nutrients often overlooked by remote sensing and yet are the main determinants of water quality can be remotely sensed. Sampling targeted ammonia, nitrates and reactive phosphorus from May to October 2015. In situ nutrient concentrations were regressed against reflectance derived from Landsat 8 imagery. Strong negative relationships were found between ammonia and the near-infrared band in July (R² = 0.80, p < 0.05) as well as between nitrates and the blue band (R² = 0.67, p < 0.05) in June. Overall, the results suggest that the cool dry season is the optimum time to use Landsat 8 for monitoring nutrients in tropical lakes.  相似文献   

岱海近400年以来的环境变化:高分辨率XRF岩芯扫描结果的研究     

辛首臻  成艾颖  余俊清  高春亮  洪荣昌  张丽莎 《盐湖研究》2015,(2):1-6,33

岱海是东亚夏季风边缘地带的闭流型半咸水湖泊,其汇水流域降水量的变化易于引发湖泊水位和水化学变动。选用DH11-1岩芯进行1 mm分辨率XRF元素扫描分析,并对测试结果进行多元数理统计分析,旨在查明这些元素与外源碎屑、自生碳酸盐沉积以及岱海水位、水化学变化的关联。结果显示,Si、Al、Ti、K、Fe、Rb等元素相关性好,并呈现相似的变化趋势,其含量变化与主要河流带入的碎屑物的多寡有关;Ca元素主要反映沉积物中自生碳酸盐即文石和方解石矿物含量的增减。研究发现,在人类活动严重影响之前,岱海在过去~400年期间的环境特征总体可划分为4个阶段,各阶段的水位、水化学特征及水量平衡有所不同,总体受汇水盆地降水量变化的控制。此外,沉积物中Cu、Zn、Cr可能与人类活动影响有关。  相似文献