应用陆地卫星TM数据判别湿地生态系统--以辽宁阜新地区为例     

王恩德 《地质与资源》2004,13(3):159-166

辽宁省阜新地区东北部有一片广阔的沼泽湿地区域,富有含多种动植物区系群的植被类型.然而,由于多年的河流改道、气候干燥使得原始沼泽地开始干涸.经济的发展导致湿地不断地被开发,湿地中有机物的衰减造成水禽类数量的锐减.因此,为适当地保护、规划和管理而对湿地区域进行判别并填图是十分重要的.国家已拥有许多根据航片判别的湿地图录,但这些图录中还存在着航片解译及填图过程中产生的人为误差.因为小型湿地一般不易与周围小规模的高地区别开来,所以它们可能未被绘在地形图上.卫星数据的应用提供了一种解决此问题的方法,因为计算机能够判别最小的潜在的湿地区域,这是人类裸眼所不能辨别出来的.本研究正是以此为基础的.随着一种利用陆地卫星TM数据来判别湿地的新技术的应用,对于高植被区域或水体的识别受到了更多的重视,因为这些区域成为湿地的可能性较高.所获得的结果根据地面实情并利用现有资料如地形图和航片等进行了评估.陆地卫星TM数据为湿地填图提供了一种既快捷又具成本效益的方法.在中国,所有地区的这种图像一般都可获得,并且有保存完好的历史档案,这便容许我们选择最合适的不同季节的图像进行分析.  相似文献   

山东东平湖的变迁与黄河改道的关系   总被引：7，自引：5，他引：2       下载免费PDF全文

喻宗仁  窦素珍  赵培才  刘桂成  张成  裴放 《古地理学报》2004,6(4):469-479

根据历史文献以及巨野、梁山、戴庙钻孔剖面的分析与研究及对东平湖底沉积的调查,确定了大野泽、梁山泊、安山湖、东平湖的沉积记录,提出东平湖由大野泽、梁山泊、安山湖演化而来。通过对东平湖演化与黄河决口和改道关系的分析与对比,指出历史时期东平湖演化历程与黄河关系密切,经历了黄河决口注入和改道流经湖区,河水注入、湖面扩大,河徙水退、湖面萎缩。黄河第一次大改道期间注入和一次改道流经大野泽。黄河第二次大改道期间两次注入、其中一次改道流经大野泽,水面北侵形成梁山泊。黄河第三次大改道期间三次决口注入,两次改道流经梁山泊,湖面进一步扩大成“八百里梁山泊”,之后黄河仅数次决入,水源短缺,湖面萎缩。黄河第四次大改道期间未流入梁山泊,湖面进一步缩小。黄河第五次大改道期间曾两次注入梁山泊,湖面又扩大成为一片泽国,而后断绝黄河水源,被分成安山湖等北五湖,梁山泊岁久填淤,变湖为陆。黄河第六次大改道期间黄河水源断绝,北五湖水面北移,逐渐萎缩消失,仅安山湖经历一次黄河决入,并淤塞而成东平湖,黄河水断绝时湖底干涸,黄河大汛期曾倒灌入湖。  相似文献   

稀土氧化物及黏土负载La₂O₃除磷性能的实验研究     

柴锡炯  尹琳  陆现彩 《岩石矿物学杂志》2019,38(6):799-806

地表水体富营养化现象与磷的积累有密切关系,去除水体中溶解态磷是降低富营养化风险的技术关键。近十余年来,稀土元素被用于污水除磷剂的开发,并获得了良好的应用成效。本文实验比较了8种结晶态稀土氧化物(Y_2O_3、La_2O_3、CeO_2、Pr6O11、Nd_2O_3、Sm_2O_3、Eu_2O_3和Dy_2O_3)的除磷性能,结果表明La_2O_3的除磷性能最好,Pr6O11、Y_2O_3、Eu_2O_3、Nd_2O_3次之,Sm_2O_3和Dy_2O_3效果微弱,CeO_2完全没有除磷能力;研究表明稀土氧化物表面磷吸附的动力学行为更符合准一级反应模型,吸附等温线符合Langmuir模型。实验表征了除磷后的稀土氧化物和除磷过程中溶液p H值的变化,认为稀土氧化物除磷是一个表面吸附占主导,氧化物溶解出来的离子辅助沉淀的吸附过程。为了避免稀土氧化物颗粒在水体中发生团聚并降低表面吸附能力,将稀土氧化物La_2O_3微纳米颗粒负载在不同黏土矿物上,发现负载于黏土矿物表面的稀土氧化物除磷能力有较好提升,磷吸附量均提高25%左右。负载等量La_2O_3的3种黏土矿物的除磷性能差异不显著,黏土矿物提高稀土氧化物颗粒分散度可能是后者除磷能力提升的主要原因。  相似文献   

吹填场区双层软黏土地基承载特性及破坏模式     

雷华阳  刘广学  周骏 《岩土力学》2019,40(1):260-268

针对天津滨海地区围海造陆工程所形成的上软、下硬双层软黏土地基,利用室内载荷试验和数值模拟开展了双层软黏土地基的承载特性及破坏模式研究。研究表明：由于下层沉积土的补强效应,双层软黏土地基的P-S曲线会出现明显的凹凸转折点,其出现的位置与宽厚比密切相关,宽厚比越小,转折点出现的时间越靠后,下层沉积土的补强效果越不明显。数值结果表明：双层软黏土地基破坏模式随着上覆土厚度的变化相差不大,均为整体剪切破坏。随着载荷板宽度的增加,双层软黏土地基以冲剪破坏模式过渡为局部剪切破坏,当载荷板宽度大于3.0 m时,表现为整体剪切破坏。  相似文献   

粉质黏土变形特性的冻融循环效应及其双屈服面本构模型     

胡田飞  刘建坤  王天亮  岳祖润 《岩土力学》2019,(3):987-997

  相似文献   

有明黏土各向异性固结特性的试验研究     

加瑞  雷华阳 《岩土力学》2019,40(6):2231-2238

由于大多数黏土矿物是片状的,在沉积和随后的固结过程中黏土颗粒和组构单元趋向水平定向排列,使天然沉积黏土呈现各向异性的固结特性。通过垂直切和水平切试样的恒应变速率固结试验研究了日本有明黏土的各向异性固结特性。试验结果表明,水平切试样的先期固结压力pch与垂直切试样的先期固结压力pcv的比值在0.5～1.0之间,主要是因为天然沉积黏土各向异性的屈服轨迹以及垂直切和水平切试样所经历的应力路径不同;在正常固结阶段,水平切试样的固结系数ch与垂直切试样的固结系数cv之比约为1.43,水平切试样的渗透系数kh与垂直切试样的渗透系数kv之比约为1.40,水平切试样的体积压缩系数mh与垂直切试样的体积压缩系数mv基本相等。因此,有明黏土固结系数的各向异性主要是因为渗透系数的各向异性,而渗透系数的各向异性本质上是因为其微观结构的各向异性。  相似文献   

大面积填土场地中摩擦型桩负摩阻力分布特性研究     

叶观宝  郑文强  张振 《岩土力学》2019,40(Z1):440-448

中国大面积场地形成工程日益增多,在缓解土地供求矛盾的同时也带来了诸多工程问题,如场地大面积沉降会造成桩基负摩阻力增加,影响桩基安全性,但针对大面积填土场地中桩基负摩阻力研究成果较少。结合某现场试验,建立了单桩有限元分析模型,与实测数据对比验证模型的合理性。基于验证后的数值分析模型,研究了大面积填土场地工程中填土天然重度及厚度、桩顶和地表荷载及场地形成时间对摩擦型桩下拉荷载和中性点的影响。结果表明,填土厚度和桩顶荷载的变化显著影响中性点的位置;填土的天然重度和厚度越大,下拉荷载越大;场地固结时间越长,下拉荷载越小;减小桩顶荷载和增加地表堆载会增大下拉荷载。敏感度分析表明,相比荷载因素,场地形成因素对下拉荷载及桩顶沉降影响更为显著。最后,结合国内外规范讨论了考虑大面积填土场地中摩擦型桩负摩阻力计算方法的适用性。研究结果对大面积填土场地摩擦型桩设计具有参考价值。  相似文献   

Last Deglacial Soft−Sediment Deformation at Shawan on the Eastern Tibetan Plateau and Implications for Deformation Processes and Seismic Magnitudes     

ZHONG Ning  JIANG Hanchao  LI Haibing  XU Hongyan  SHI Wei  ZHANG Siqi  WEI Xiaotong 《《地质学报》英文版》2019,93(2):430-450

The eastern margin of the Tibetan Plateau is characterized by frequent earthquakes; however, research of paleo?earthquakes in the area has been limited, owing to the alpine topography and strong erosion. Detailed investigations of soft?sediment deformation (SSD) structures are valuable for understanding the trigger mechanisms, deformation processes, and the magnitudes of earthquakes that generate such structures, and help us to understand tectonic activity in the region. To assess tectonic activity during the late Quaternary, we studied a well?exposed sequence of Shawan lacustrine sediments, 7.0 m thick, near Lake Diexi in the upper reaches of the Minjiang River. Deformation is recorded by both ductile structures (load casts, flame structures, pseudonodules, ball?and?pillow structures, and liquefied convolute structures) and brittle structures (liquefied breccia, and microfaults). Taking into account the geodynamic setting of the area and its known tectonic activity, these SSD structures can be interpreted in terms of seismic shocks. The types and forms of the structures, the maximum liquefaction distances, and the thicknesses of the horizons with SSD structures in the Shawan section indicate that they record six strong earthquakes of magnitude 6–7 and one with magnitude >7. A recent study showed that the Songpinggou fault is the seismogenic structure of the 1933 Ms7.5 Diexi earthquake. The Shawan section is located close to the junction of the Songpinggou and Minjiang faults, and records seven earthquakes with magnitudes of ~7. We infer, therefore, that the SSD structures in the Shawan section document deglacial activity along the Songpinggou fault.  相似文献   

Petrological and Organic Geochemical Characteristics of Oil Sands from the Middle Jurassic Yan'an Formation in the Southern Ordos Basin,China     

SUN Sumei  ZHAO Xiaohui  LI Zhi  ZHAO Qian  KANG Xiaoshan  ZHANG Qi 《《地质学报》英文版》2019,93(Z2):79-80

An integrated petrological and geochemical analysis of surface and drilled oil sands was conducted to assess the organic matter origin/type, thermal maturity and paleoenvironment. Petrographic analysis of the oil sand used to establish the relationships between porosity and permeability with bulk density, RQI, NPI and FZI. The strong correlation between reservoir quality index (RQI) and permeability (R² = 0.98) reveal that porosity has a good correlation to RQI. The biomarker signatures of the analyzed oil reveal predominance of subaquatic‐derived source input with mainly land plant materials. This was indicated based on the average concentration of αααC27:C28:C29 sterane 20R of about 38%, 22% and 40% respectively. This interpretation is also supported by high values of tricyclic terpane/αβC30 hopane and regular sterane/αβC30 hopane. An anoxic condition of deposition within a lacustrine paleoenvironment that attributed to the enhancement of the preservation of the organic matters in the area were indicated based on the low Pr/Ph ratios (average 0.74), low values of αβC31‐22R‐hopane/αβC30 hopane ratios and high C26/C25 tricyclic terpane ratios as well as the presence of gammacerane and a low water salinity. Biomarker maturity parameters show that the extracted oil sand has entered the early oil window stage.  相似文献   

Stalked barnacles (Cirripedia,Thoracica) from the Upper Jurassic (Tithonian) Kimmeridge Clay of Dorset,UK; palaeoecology and bearing on the evolution of living forms     

Andy Gale 《Proceedings of the Geologists' Association. Geologists' Association》2019,130(3-4):355-365

New thoracican cirripede material from the Kimmeridge Clay (Upper Jurassic, Tithonian) is described. This includes a log, encrusted on the lower surface with hundreds of perfectly preserved, articulated specimens of Etcheslepas durotrigensis Gale, 2014, and fewer specimens of Concinnalepas costata (Withers, 1928). Some individuals are preserved in life position, hanging from the underside of the wood, and the material provides new morphological information on both species. It appears that Martillepas ovalis (Withers, 1928), which occurs at the same level (Freshwater Steps Stone Band, pectinatus Zone) attached preferentially to ammonites, whereas E. durotrigensis and C. costata used wood as a substrate for their epiplanktonic lifestyle. Two regurgitates containing abundant barnacle valves, mostly broken, and some bivalve fragments, have been found in the Kimmeridge Clay. These were produced by a fish grazing on epiplanktonic species, and are only the second example of regurgitates containing barnacle valves known from the fossil record. The evolution of modern barnacle groups is discussed in the light of the new Jurassic material as well as recently published molecular phylogenies. New clades defined herein are called the Phosphatothoracica, the Calamida and the Unilatera.  相似文献