Distribution,chemical speciation and source of trace elements in surface sediments of the Changjiang Estuary     

Li-Qin Duan  Jin-Ming Song  Hua-Mao Yuan  Xue-Gang Li  Ning Li  Ji-Kun Ma 《Environmental Earth Sciences》2014,72(8):3193-3204

To evaluate biogeochemical characteristics, eco-environmental risks and sources of trace elements (TEs: As, Hg, Se, Sb, Te, Sn, Bi and Ge), their total concentrations and chemical speciation in surface sediments collected from the Changjiang Estuary were determined. Total concentrations for As, Hg, Se, Sb, Te, Sn, Bi and Ge were 4.57–30.20, 0.01–0.40, 0.04–0.38, 0.36–1.48, 0.02–0.10, 0.48–6.58, 0.13–0.64 and 0.83–2.43 μg/g, respectively, with higher values at the estuary. This distribution pattern was attributed to the riverine input and high clay and total organic carbon contents. The sequential extraction suggested that TEs mainly occurred in residual fractions. The risk assessment code suggested that As, Hg and Sn were at low risk, whereas Bi, Se, Sb, Te and Ge were at medium risk. The geoaccumulation index (I _geo) and principal component analysis indicated that Se and Sn mainly came from the natural input (crustal and biological inputs), whereas As, Sb, Hg, Bi and Te came from both of the crustal and anthropogenic inputs via atmosphere and rivers. In addition, Ge possibly came from the natural (crustal and biological inputs) and anthropogenic inputs.  相似文献   

海洋CSEM和MT一维联合反演研究     

赵宁  王堃鹏  秦策 《物探化探计算技术》2014,(2):148-151

传统频率域海洋可控源电磁(MCSEM)法利用极化方向电场实部与虚部信息进行反演,由于海底沉积层电阻率一般较低,在海底浅部能取得较为理想的反演效果,但难以探测到海底几千米下的深部基底。这里利用海洋可控源电磁和海洋大地电磁(MT)一维联合反演程序,采用奥克姆反演算法,尝试对海洋电阻率模型进行联合反演。通过反演试算发现,利用频率更低的海洋MT加入反演,不会影响浅部反演效果,同时能探测到深部基底,为海底油气勘探提供了更多技术手段。  相似文献   

The Deep Geophysical Structure of the Middle Section of the Longmen Mountains Tectonic Belt and its Relation to the Wenchuan Earthquake   总被引：1，自引：0，他引：1  

YU Nian  WANG Xuben  HU Xiangyun  CAI Xuelin  KAN Aike  ZHAO Ning 《《地质学报》英文版》2014,88(2):483-497

Investigation of the deep geophysical structure of the Longmen Mountains tectonic belt and its relation to the Wenchuan Earthquake is important for the study of earthquakes. By using magnetotelluric sounding profiles of the Luqu–Zhongjiang and Anxian–Suining; seismic sounding profiles of the Sichuan Maowen–Chongqing Gongtan, the Qinghai Huashi Gorge–Sichuan Jianyang, and the Batang–Zizhong; and magnetogravimetric data of the Longmen Mountains region, the deep geophysical structure of the Songpan–Ganzi block, the western Sichuan foreland basin, and the Longmen Mountains tectonic belt and their relation was discussed. The eastward extrusion of the Qinghai–Tibet Plateau thrusts the Songpan–Ganzi block upon the Yangtze block, which obstructs the eastward movement of the Qinghai–Tibet Plateau. The Maoxian–Wenchuan, Beichuan–Yingxiu, and Anxian–Guanxian faults of the Longmen Mountains fault belt dip to northwest with different dip angles and gradually converge in the deeper parts. Geophysical structure suggests that an intracrustal low-velocity, low-resistivity, and high-conductivity layer is common between the middle and upper crust west of the Longmen Mountains tectonic belt but not in the upper Yangtze block. The Sichuan Basin has a thick low-resistance sedimentary layer on a stable high-resistance basement; moreover, there are secondary paleohighs and depression structures at the lower part of the western Sichuan foreland basin with characteristic of high magnetic anomalies, whereas the Songpan–Ganzi block has a high resisitivity cover of upper crust and continues to a low-resistance layer. Considering the Longmen Mountains tectonic belt as the boundary, there are Bouguer gravity anomalies of "one belt between two zones." Thus, we infer that there is a corresponding relation between the inferred crystalline basement of the Songpan block and the underlying basin basement of the Longmen Mountains fault belt. Furthermore, there may be an extensive ancient Yangtze block, which is west of the Ruoergai block. In addition, the crust–mantle ductile shear zone under the Longmen Mountains tectonic belt is the main fault, whereas the Beichuan–Yingxiu and Anxian–Guanxian faults at the surface are earthquake faults. The Wenchuan Ms 8.0 earthquake might be attributed to the collision of the Yangtze block and the Qinghai–Tibet Plateau. The eastward obduction of the eastern edge of the Qinghai–Tibet Plateau and eastward subduction of its deeper part under the influence of the collision of the Indian, Pacific, and Philippine Plates with the Eurasia Plate might have caused the Longmen Mountains tectonic belt to cut the Moho and extend to the middle and upper crust; thus, creating high stress concentration and rapid energy release zone.  相似文献   

复合胎体金刚石钻头试验研究     

孙鑫  王迪  孙宁  雷明善 《吉林地质》2014,(3):137-138

为解决坚硬岩层钻进效率低下,研究设计一种复合胎体金刚石钻头,在软岩层进尺快,在硬岩层亦能获得相对较高的钻进速度,突破了单靠降低胎体硬度的传统设计理念,获得了满意钻进效率。  相似文献   

多层叠置含煤层气系统不同排采制度下的排采效应     

孙鹏杰  姚文涛  孙宁  魏甜 《中国煤炭地质》2014,(12):33-35

在多煤层发育地区,各煤层组之间发育低渗透岩层,使得上下煤组之间形成独立的多层叠置含煤层气系统。根据相对独立含气系统理论对西山煤田南部赤峪地区的多煤层进行了含气系统的划分,并对储层压力、临界解吸压力等参数进行了分析,在此基础上采用COMET3数值模拟软件进行了单层排采、合层排采和递进排采分析。模拟结果显示：单层排采产量低,经济可采时间短,且成本较高;合层排采比单层排采产量高,经济可采时间长,但各含气系统之间由于相互干扰,贡献不一,使资源浪费;递进排采产气量和稳产时间均优于前两者。可根据产气压力来确定多层叠置含煤层气系统排采次序,首先排采产气压力最高的含气系统,当压力降至压力低的系统时再合排。  相似文献   

Analyzing regional economic impact and resilience: a case study on electricity outages caused by the 2008 snowstorms in southern China   总被引：2，自引：1，他引：1  

Aijun Hu  Wei Xie  Ning Li  Xuanhua Xu  Zhonghui Ji  Jidong Wu 《Natural Hazards》2014,70(2):1019-1030

When we think about the loss caused by natural disasters, we generally think about the direct economic loss. Although the direct economic loss is often obvious, the subsequent indirect economic loss can also be quite substantial. This research is a case study about the indirect economic impact of the Hunan electricity disruptions resulting from the 2008 snowstorms in southern China. Utilizing the computable general equilibrium model, this study shows that the indirect economic loss in Hunan Province resulting from electricity supply disruptions is estimated at USD 372 million over a 3-month recovery period. We also compare our results with other studies that use input–output models and discuss how the total regional economic resilience can mitigate economic losses through market substitutions and price changes.  相似文献   

内蒙古额仁陶勒盖银矿区火成岩岩石地球化学特征及锆石SHRIMPU-Pb同位素定年   总被引：2，自引：1，他引：1  

许立权  刘翠  邓晋福  李宁  戴蒙  白立兵 《岩石学报》2014,30(11):3203-3212

通过对额仁陶勒盖银矿区的塔木兰沟组中酸性火山岩详细的岩石地球化学特征研究表明,该套火山岩具高硅(SiO₂>57%)、高铝(Al₂O₃>16%)、富碱尤其富钾(K₂O>3%)特征,属HKCA系列;稀土含量中等(187×10^-6~240×10^-6),(La/Yb)_N在18.6~27.9,Yb<1.90×10^-6,Y<18.0×10^-6,δEu=0.85~0.96,轻重稀土分馏强烈,明显亏损重稀土,无或略具负铕异常;微量元素相对富集Rb、Ba、Th、U、K等大离子亲石元素(LILE),亏损高场强元素Nb、Ta、Ti、HREE,与活动陆缘火成岩的微量元素特征一致.塔木兰沟组安山质火山岩特征表明,安山质岩浆来源较深(>50km),起源于加厚地壳底部,源区残留为石榴石、单斜辉石及角闪石,岩浆在部分熔融及后期演化过程中不曾与斜长石平衡过,可能是蒙古-鄂霍茨克洋闭合后进入碰撞后松弛阶段,钙碱性或高钾钙碱性的中基性变火成岩的部分熔融形成.对与额仁陶勒盖银矿关系密切的石英斑岩(脉)测年,获得SHRIMP U-Pb年龄138.6±2.3Ma,为石英斑岩的成岩年龄,进一步限定该银矿床形成于早白垩世早期.对塔木兰沟组安山岩与石英斑岩成岩年龄、矿床成矿特征等方面进行探讨了,认为该银矿床为岩浆热液成因.  相似文献   

时空Kalman滤波在变形分析中的应用研究     

石强  戴吾蛟  晏慧能  刘宁 《测绘学报》2022,51(10):2125-2138

时空Kalman滤波可对变形监测数据进行时空滤波去噪、数据插补和变形预测,本文利用时空Kalman滤波进行变形分析,从模型原理及试验两方面比较分析了Kriged Kalman filter(KKF)、space time Kalman filter(STKF)和spatio-temporal mixed effects(STME) 3种典型时空Kalman滤波模型的性能和适用性。结果表明:3种时空Kalman滤波模型均基于空间基函数及动力学模型组合形式描述时空数据的时空相关性,其主要差异在于空间变异的描述形式不同、空间基函数和状态转移矩阵构造过程不同及模型降维方法不同。在适用性方面,KKF模型更适合于稀疏测站的变形分析,STKF模型及STME模型更适合于海量测站的变形分析。在变形分析应用效果方面,3种时空Kalman滤波模型均具有较高精度的时空滤波去噪、数据插补和变形预测性能,其滤波结果相对于普通Kalman滤波结果的平均改善率为21.1%,其缺失数据插补结果相对于Hermite时间插值结果的平均改善率为42.4%,其空间预测结果相对于Kriging空间插值结果的平均改善率为65.3%,其对已知测站未来变形的时空预测结果相对于普通Kalman滤波时间预测结果的平均改善率为20.6%,其对非观测站点未来变形的时空预测结果相对于Kalman滤波+Kriging组合模型预测结果的平均改善率为20.5%。  相似文献   

气候变化与土地利用/覆被变化对中国北方农牧交错带水资源影响研究进展   总被引：1，自引：0，他引：1  

陈雪萍  赵学勇  王瑞雄  宁志英  卢建男  赵思腾 《中国沙漠》2022,42(3):170-177

中国北方农牧交错带对全球变化响应敏感,研究气候变化及土地利用/覆被变化（LUCC）背景下北方农牧交错带水资源问题,对变化环境下生态脆弱区的水资源利用与管理具有重要意义。通过对北方农牧交错带气候与LUCC演变特征及其对水资源影响等方面的综合研究,总结得出：（1） 近几十年,该地区气候呈暖干化趋势,气温升高速率与降水减少速率均高于全球平均水平。（2） LUCC以农牧相互转化为主,土地利用结构未发生明显变化。（3） 该地区流域径流、地下水位与气温负相关,与降水量正相关,且降水作用更明显;近几十年来,LUCC成为影响该地区生态水文过程的主导因素,对水资源影响的贡献率越来越大。同时,针对目前研究中存在的问题及薄弱环节,提出未来研究的发展趋势和亟需重点加强的研究方向。  相似文献   

地缘政治视角下的跨境移民和族裔社区研究     

安宁  张博 《世界地理研究》2022,31(6):1119-1129

在全球-地方频繁互动的今天,跨国/跨地方逐渐成为超高速流动的社会现实,移民与流入流出地的多元互动模糊了国与国、地方与地方之间的边界,在目的地不断重塑社会结构和空间,在物质和符号维度赋予了地方不同的意义。族裔社区不仅仅反映了不同的移民群体复杂的日常生活实践及其在空间上的互动,也将对多元化族裔空间的关注转移到社区、空间、领土政治甚至流动地缘想象,同时也将族裔社区空间纳入一个关系性的视角下。而传统上地缘政治视角对移民和族裔空间的关注相对有限。因此,本专栏主要讨论地缘政治视角下的跨境移民和族裔社区。具体而言,专栏首先回顾了地缘政治研究及其对流动性的关注和移民研究中的地缘政治面向,其次通过8篇文章讨论了不同尺度下多元的跨境移民及族裔社区营造与建构的相关研究,希冀从理论、方法以及实证研究方面对现有知识进行补充,也尝试通过探索国内外相关研究的进展,为社会和国家治理的需求服务。  相似文献