Human’s digital footprints on the Qinghai-Tibet Plateau: Variations during festivals and impacts on nature reserves     

Du  Yunyan  Tu  Wenna  Liang  Fuyuan  Yi  Jiawei 《地理学报(英文版)》2021,31(2):179-194

Mobile internet and wireless communication technologies have produced unprecedented location-aware data. Such big geospatial data can be used as a proxy measure of the ‘digital footprints' left by us on the planet and provide a valuable opportunity to understand the dynamic and short-term human disturbance on the nature at fine scales. This study investigated the spatiotemporal variations of human's digital footprints on the Qinghai-Tibet Plateau using smartphone-users-generated Tencent's location request data. The results showed that human's digital footprints cover less than 5% of Qinghai and Tibet, exhibiting either a U-shaped or an N-shaped temporal change pattern during the major festivals. Spatial changes of the digital footprints manifested a transition process from dispersion to concentration in Xining and Lhasa. Human disturbance assessment of seven large nature reserves on the plateau showed that the Qinghai Lake is the most disturbed one as shown by 14.6% of its area is stained with human digital footprints and the areal average of footprint intensity is 1.59, and the disturbance was significantly escalated during the National Day holiday. By contrast, the Qangtang and Hoh Xil are the least affected nature reserves with the two indices less than 1% and 0.1, respectively.  相似文献   

The lithosphere structure of Northeast China     

Xingzhou Zhang  Baojun Yang  Fuyuan Wu  Guoxing Liu 《Frontiers of Earth Science》2007,1(2):165-171

The lithosphere of northeastern China is composed of the Erguna, Xingan, Songnen, Jiamusi blocks and Mesozoic Wandashan accretionary complex from west to east. Nd isotope model ages indicate that the Xingan and Songnen blocks have the same Nd model ages ranging from 500 to 1 000 Ma. These are obviously younger than those of the Jiamusi block (1 500–2 000 Ma) and the Erguna block (1 500–1 700 Ma), reflecting the different evolutions of individual blocks in the early times. Geochemical tracing analysis shows that the Nd model ages of Paleozoic supercrustal rocks in the four blocks are dominantly Mesoproterozoic, while those of Mesozoic granites are mainly Neoproterozoic. It is shown that the crust ages of the region are characterized by being younger in the lower part and older in the upper part. The Os isotope analysis also indicates that the lithosphere mantle of the region is characteristic of a younger age. The P-wave velocities of the region show more complicated structures in lithosphere and asthenosphere. First of all, notably different from traditional concept of the seismic lithosphere, the low velocity zone of the lithosphere beneath the region has no persistent and continuous top interface which is highly varied in depth and intersected with the high velocity layers, forming sharp velocity discontinuities beneath major tectonic belts, even up to the Moho beneath some tectonic units. But the bottom interface of the low velocity zone is relatively persistent, occurring at a depth of 230–240 km. Another feature is that the lithosphere is characterized by an “overpass type” velocity structure vertically, in which the contoured velocity is distributed in the NE trending within the crust, in a nearly NS trending in the lithosphere mantle from a depth of 45 to 90 km, in a nearly EW trending in the upper part of the asthenosphere from 90 to 170 km and in a ring-like distribution with a diameter of about 300 km in the lower part of the asthenosphere from 170 to 240 km. The P-wave velocity is progressively increasing from 240 to 400 km.  相似文献   

基于地统计学的甘肃臭草群落土壤水分空间异质性   总被引：1，自引：0，他引：1  

史丽丽  赵成章  高福元  张军霞  张静 《山地学报》2011,29(6)

土壤水分是植被格局形成和演变的主要因素,土壤水分的空间异质性对于认识干旱区草原植物对环境的响应机制具有重要意义.应用地统计学方法,对祁连山北坡甘肃臭草(Melica przewalskyi)退化草地土壤表层含水量的变异性进行研究.结果表明,臭草型退化草地浅层(0 ～30 cm)土壤水分符合正态分布,土壤含水量沿垂直方向逐渐增大,介于9.56％ ～11.21％.各层土壤水分的变异系数分别为12.97％ (0～10 cm)、8.8％ (10～20 cm)和14.09％ (20～30 cm),均属弱变异;0～ 30 cm土壤含水量具有高度的空间异质性,其中34.92％～42.71％的空间异质性是由空间自相关部分引起的,主要体现在16.87 ～ 69.14 m尺度上.在0～ 10 cm土层,引起土壤水分空间变异的主要因素是植被覆盖度的不同,而在10 ～ 30 cm土层,土壤水分空间变异性主要是根系分布的差异引起的.  相似文献   

川滇区域高频地震动地形效应初探          下载免费PDF全文

周田宇  梁富源  马完君  谢志南 《世界地震工程》2022,38(4):026-35

历次强震表明:局域起伏地形对由高频地震动起决定作用的震害存在显著影响。忽略场地浅表土层的影响,凸起地形场地震害高于凹陷地形。然而,由于地形效应影响因素的复杂多样以及公认地形效应表征模型的缺失,已有的宽频带地震动模拟与预测方法并未考虑高频地震动地形效应,这可能导致对地震动时程及参数的错误估计。为此,本文利用当前较具代表性的地形效应量化表征模型,初步分析了川滇区域高频地震动的地形效应。首先,给出了基于量化表征模型的区域高频地震动地形效应计算分析方案;其次,完整地阐述了该方案在川滇地区的应用,并结合漾濞地震震害考察结果初步验证了川滇高频地震动地形效应分析结果的可靠性;最后,讨论了分析结果的局限并给出其应用于宽频带地震动模拟与预测方法中的初步建议。  相似文献   

Aeolian component records in lacustrine sediments and its atmospheric circulation significance for evolution of Qarhan salt lake,NE Qinghai-Tibetan Plateau     

AN Fuyuan  LAI Zhongping  FAN Qishun  WEI Haichen  MA Haizhou 《《地质学报》英文版》2014,88(Z1):1-2

正1 Introduction The Qarhan Playa of Qaidam Basin is located at the northeastern QinghaiTibetan Plateau(QTP),in which thick lacustrine and evaporate sediments deposited since the late Pleistocene(Chen et al.,1985,1986).As surrounded by capacious Gobi and yardang fields and suffered strong westerly-northwesterly wind,abundant aeolian materials were trapped in these sediment sequences in the  相似文献   

成德绵地区政区位势与行政区经济耦合的时空演化与优化路径     

冯润东  王甫园  王开泳 《地理研究》2022,41(2):441-455

行政区划作为国家治理体系的基础支撑,对区域经济发展具有重要影响。深入探究行政区划与区域经济的时空耦合关系与优化路径,有助于制定区域一体化发展政策。本文以成德绵地区为例,基于政区位势模型、行政区经济模型和位序规模理论,定量识别2005—2018年政区位势与行政区经济的耦合与空间演变,并从体制机制改革、行政区划调整等角度提出优化路径。研究表明：① 成德绵地区政区位势和行政区经济分别经历了“沿交通线轴向扩散”和“中心极化-中部辐射递减-外围塌陷”的演化过程。② 根据政区位势位序规模相对于行政区经济位序规模的耦合关系,将政区耦合类型划分为位势靠前、区划适应型,位势靠前、区划约束型,位势落后、区划适应型,位势落后、区划约束型。③ 研究区耦合类型表现为“位序落后型收缩-区划适应型增加-位势靠前型主导”的演变特征,位势靠前、区划约束型占比最高（45.0%）,市辖区和北部外围政区发展潜力大幅提升的同时,三市交界处行政区经济约束相对较强。成德绵地区作为中国西部地区的重要增长极,未来应结合不同政区类型的实际情况,通过增强政府间合作、充分利用中心城市的辐射带动效应、转变政府职能和审慎稳妥推行行政区划调整工作等方式,促进区域一体化和城市群经济高质量发展。  相似文献   

溢油海面的Marangoni效应分析     

杨永生  胡伏原  傅朝阳  吴俊 《海洋湖沼通报》2012,(4):36-40

溢油海面的"Marangoni"效应是指油膜对短重力波和毛细波具有一定的抑制作用,它是SAR区分溢油与清洁海面的物理基础。本文采用Fung&Lee海浪谱和Lombardiniet溢油模型,定量分析了归一化溢油因子对波高斜率均方根的影响;根据海浪的Longuet-Higgins模型,仿真了溢油海面和清洁海面的波高样本,验证了油膜对短重力波和毛细波具有一定的抑制作用。  相似文献   

原位微区同位素分析在花岗岩成因研究中的应用   总被引：3，自引：0，他引：3       下载免费PDF全文

孙金凤  杨进辉  吴福元 《地学前缘》2009,16(2):129

花岗岩及其伴生的镁铁质岩石是构成大陆地壳的重要组成部分,是大陆形成演化的标志物。花岗岩的成因研究,包括花岗岩的岩浆源区及成岩过程,蕴含着大陆地壳生长、岩石圈演化等重要信息。随着二次离子质谱仪(SIMS)和激光多接收电感耦合等离子体质谱仪(LA-MC-ICPMS)的问世,原位微区(in-situ)元素和同位素分析方法开发以及应用使花岗岩成因研究,尤其是花岗岩的岩浆源区和成岩过程等方面得到长足的进展。在仔细阅读相关文献的基础上,结合笔者近年来相关研究工作,综述花岗岩成因研究中原位微区同位素源区示踪和成岩过程的最新进展,以期推动我国花岗岩及原位微区同位素分析方法等相关研究。  相似文献   

辽东半岛南部早前寒武纪花岗质岩浆作用的年代学格架   总被引：70，自引：5，他引：65       下载免费PDF全文

路孝平  吴福元  林景仟  孙德有  张艳斌  郭春丽 《地质科学》2004,39(1):123-138

激光ICP-MS锆石年龄测定结果显示,出露于辽东半岛南部金州地区的太古宙花岗岩形成年龄为2440～2500Ma左右,比辽宁北部—吉林南部大致同时的太古宙花岗岩形成略晚,或基本相当。结合其它地质证据,上述两者在太古宙可能是相互独立的两个块体(分别称辽南地块和辽北—吉南地块),它们在古元古代晚期因造山作用而拼合在一起。古元古代花岗岩形成于两个时期,早期形成的条痕状花岗岩侵位年龄为2160Ma,为辽河群沉积的基底岩石;晚期形成的斑状二长花岗岩和角闪辉石正长岩形成于距今约1850Ma,标志着辽吉古元古代造山作用的结束。据此,可确定辽河群沉积—变质的时限为距今2160～1850Ma,其演化时间不超过300Ma。  相似文献   

存在一种震前超低频密度—应力波的更多证据   总被引：1，自引：0，他引：1  

赵复垣 《国际地震动态》2008,(12)

笔者曾指出存在一种震前由孕震区发出的地下构造中的超低频密度-应力波,而且这种波的性质与国外学者提出的"热力学弹性回跳"理论符合得很好,并列举了天文时纬残差、地下深部物质视电阻率和震前地壳突变性形变3个方面的观测证据来证明这种波的存在.我们进一步发现,我国地震工作者在对地震的长期观测和监视工作中,实际上已经获得了支持存在这种震前超低频密度-应力波的很多实测结果.大量实测数据既是这种波存在的证据,又是研究这种波的性质的第一手资料.本文将与震前超低频密度-应力波的特征符合得较好的实测资料择要列出,并与该波的特征相比较.分析表明,这些测量所反映的很可能就是这种震前超低频密度-应力波,因此也就反映了这种波的波源-震前缓慢而剧烈的地下介质扰动.  相似文献