Impacts of karst paleo-sinkholes on mining and environment in northern China   总被引：2，自引：0，他引：2  

Shang-Xian Yin  Jincai Zhang 《Environmental Geology》2005,48(8):1077-1083

The karst paleo-sinkhole is a special geological structure widely found in the coal measures of northern China. Some paleo-sinkholes have high permeability and connectivity, making them excellent connectors between the karst aquifer and the coal seam. Consequently, during coal extraction disastrous water inrushes take place frequently, which cause severe loss not only in mine submersions and personnel casualties, but also in environmental quality. Locations and the geological and hydrogeological characteristics of paleo-sinkholes in northern China are presented. In-situ drilling and excavation results show that paleo-sinkholes have different hydrogeological behaviors in different regions and in different mines. Based on observed data, mining-induced strata failure in the seam floor is analyzed. The existence of paleo-sinkholes increases the floor strata failure zone. Numerical simulation then is adopted to model coal mining with the effects of both the paleo-sinkholes and the water pressure in the confined aquifer. Analyses of the simulation conclude that the paleo-sinkhole induces the increase in the strata failure and deformation. These make water inrushes more likely to happen.  相似文献   

北极新奥尔松地区现代污染源及其指示植物研究   总被引：5，自引：2，他引：5       下载免费PDF全文

袁林喜  龙楠烨  谢周清  尹雪斌  罗泓灏  徐晓燕  孙立广 《极地研究》2006,17(1):9-19

分析了采自北极新奥尔松(Ny-lesund)(78°55′N,11°56′E)煤矿开采区水平剖面12个点位上的三种苔原植物Dicranumangustum(苔藓类植物)、Puccinelliaphryganodes(穗状植物)和Salixpolaris(管状植物)及土壤中10种重金属(Hg、Pb、Cd、Cu、Zn、Ni、Fe、Mn、As、Se)及S、TOC的含量。结果显示采矿过程中煤层的暴露是本地区的Hg、Cd、S污染的主要来源。三种分布最广泛、数量最多的苔原植物中苔藓植物Dicranumangustum对重金属元素具有最大的富集能力,位于矿区的Dicranumangustu体内污染元素含量显著高于非矿区部分,这也说明该水平剖面上的元素污染是由当地煤矿开采导致的。同时发现,Dicranumangustum体内元素积累和土壤中元素浓度之间沿水平剖面的变化趋势较一致,能较好地反映本地区的污染状况,可以作为污染监测和指示植物。从全球区域对比来看,北极新奥尔松苔藓体内污染水平显著低于邻近的北欧等工业区,但却是北极地区Hg、Cd和S污染最严重地区,同时也比南极地区高。  相似文献   

Geochemical evidence for the variation of historical seabird population on Dongdao Island of the South China Sea     

X. D. Liu  S. P. Zhao  L. G. Sun  H. H. Luo  X. B. Yin  Z. Q. Xie  Y. H. Wang  K. X. Liu  X. H. Wu  X. F. Ding  D. P. Fu 《Journal of Paleolimnology》2006,36(3):259-279

From a rare freshwater lake characteristic of alkalescence, named “Cattle Pond”, on the Dongdao Island of South China Sea (16°39′–16°41′ N, 112°43′–112°45′ E), we collected two undisturbed sediment cores that contain seabird droppings. In this paper, we determined the concentration-versus-depth profiles of the geochemical elements in the ornithogenic sediment layers of the two cores, analyzed these profiles by various statistical methods, and studied their geochemical characteristics. The concentration profiles of As, Cd, Cu, Se, Zn, P and S are significantly correlated with each other and with loss on ignition (LOI) at 550°C, the measure for the abundance of organic matter. Similar geochemical characteristics, however, were not observed in the upper sediment layer of the Cattle Pond notably affected by cattle excrements, as well as in the bottom sediment layer compositionally dominated by coral sand and gravel. This shows that these “bio-elements” are mainly derived from seabird feces and their geochemical composition is an important geochemical characteristic of the lacustrine ornithogenic sediments. By Q-mode factor analysis (QFA) on the concentration profiles of these bio-elements, we reconstructed the historical seabird population on Dongdao Island between 1350 and 350 year B.P., and observed significant fluctuations in the calculated population. The fluctuations seem to be related to the change of sea surface temperature (SST) in the Southern China Sea. This study provides new paleoenvironmental information of past seabird population changes in low latitude areas using an indirect geochemical method.  相似文献   

有关青藏高原东北缘晚新生代扩展与隆升的讨论^*   总被引：33，自引：17，他引：33       下载免费PDF全文

张培震  郑德文  尹功明  袁道阳  张广良  李传友  王志才 《第四纪研究》2006,26(1):5-13

青藏高原晚新生代的扩展和隆升对周边环境演变产生重大影响,确定扩展和隆升的起始年代是一个重要的科学问题。近年来在六盘山、积石山和祁连山及其相邻盆地的研究表明,青藏高原东北缘晚新生代(5~10MaB.P. 或约8MaB.P. )发生了准同期、影响深远的构造变形,导致了沉积盆地的消亡和山脉的隆起。青藏高原北缘的阿尔金山和东缘的岷山、龙门山及川滇高原也在该时段发生了构造活动的加速和构造隆升。所有这些准同期的事件反映了约8MaB.P. 前后青藏高原向周边的扩展,扩展的方式是通过一系列逆冲断裂、褶皱变形、左旋走滑及其伴随的山脉隆起和盆地消亡而实现的。该时期青藏高原的扩展导致了周边的环境变化,奠定了今日环境的格局。  相似文献   

湖芯沉积物揭示的末次冰消开始时期 普莫雍错湖区环境变化^*   总被引：14，自引：22，他引：14       下载免费PDF全文

朱立平  鞠建廷  王君波  西村弥亚  守田益宗  吴艳红  冯金良  谢曼平  林晓 《第四纪研究》2006,26(5):772-780

文章讨论了末次冰消开始时期青藏高原南部普莫雍错湖芯沉积反映的环境暖湿化以及原因。通过对现代湖泊和周边河流水文状况调查,发现流域内发育众多冰川,冰川融水构成维持湖面稳定的重要来源;湖面以及湖泊沉积环境的变化与冰川融水以及相应的温度改变具有密切的联系。利用湖泊沉积岩芯PM-1孔,通过加速器¹⁴ C测年和粒度、元素、碳酸盐含量、总有机碳以及有机碳同位素、总氮、分子标志化合物、孢粉等环境指标的分析,发现在16.4~15.4cal.kaB.P.有大量流水进入湖泊,使湖面扩大,湖水加深;流域地表产生大量有机碎屑,并被流水带入湖泊进行沉积;流域内的喜湿植被得以发展。该时段湖泊扩张、陆源植被发展的原因一方面得益于冰期过后气候向温暖湿润方向转化,另一方面温度上升带来大量冰川融水则可能具有更加重要的影响,对于深入理解当前青藏高原冰川普遍退缩和一些湖泊的水面上涨具有重要的参考价值。  相似文献   

龙感湖沉积物中人类活动导致的营养盐累积通量估算^*   总被引：8，自引：9，他引：8       下载免费PDF全文

吴艳宏  王苏民 《第四纪研究》2006,26(5):843-848

通过LL-4孔沉积环境指标研究表明,近100年来龙感湖地区人类活动加强,导致营养元素磷、碳、氮以及铁在沉积物中的浓度均呈增长趋势,特别是1950年以来,随着大量人口的迁入,围湖造田、破坏湖滨湿地等造成水土流失加剧,沉积物质量累积速率加快,同时营养元素累积量急剧增加。根据营养元素与参比元素Al, Fe和Ti之间的关系,以及不同营养元素之间的相互关系,人类活动引起的累积量得以从自然背景上区分出来,结合沉积物质量累积速率计算,人类活动引起的磷、有机碳和氮的累积通量分别在151.0~889.4mg/m²a,4.3~149.0g/m²a和0.5~18.6g/m²a间变化。碎屑物质的累积稀释了沉积物中营养盐的富集浓度,龙感湖草型湖泊的特点,使湖泊沉积环境易于呈氧化环境,生物和地球化学作用,也削弱了人类活动累积营养盐的变化幅度,使沉积中营养盐呈平稳上升的趋势。  相似文献   

基于弹性波阻抗的拉梅参数反演与应用   总被引：3，自引：0，他引：3  

王保丽  印兴耀 《应用地球物理》2006,3(3)

(Connolly的弹性阻抗(EI)公式是纵、横波速度、密度和入射角的函数,应用该公式的常规反演方法只能直接得到纵、横波速度和密度的信息,而且不同角度的弹性阻抗在数值上差别很大,不在同一尺度上,无法进行对比。本文针对常规反演方法的缺点,提出了基于Gray的Zoeppritz近似方程的新的弹性阻抗公式,并对这个公式进行了标准化以实现不同角度的弹性阻抗在数值上的统一,最后用标准化后的公式进行了反演,利用拉梅参数与弹性阻抗问的线性关系可从反演得到的弹性阻抗数据体中直接提取得到拉梅参数。应用实例表明用这种方法提取得到的弹性参数更加稳定、准确,而且能很好地反映储层信息。这种新的方法是对以Connolly公式为基础的传统方法的改进。  相似文献   

Acoustic Emission Experiments of Rock Failure Under Load Simulating the Hypocenter Condition   总被引：3，自引：0，他引：3  

Hui-hui Zhang  Xiang-chu Yin  Nai-gang Liang  Huai-zhong Yu  Shi-yu Li  Y. C. Wang  C. Yin  Victor Kukshenko  Nikita Tomiline  Surguei Elizarov 《Pure and Applied Geophysics》2006,163(11-12):2389-2406

A series of acoustic emission (AE) experiments of rock failure have been conducted under cyclic load in tri-axial stress tests. To simulate the hypocenter condition the specimens are loaded by the combined action of a constant stress, intended to simulate the tectonic loading, and a small sinusoidal disturbance stress, analogous to the Earth tide induced by the Sun and the Moon. Each acoustic emission signal can indicate the occurrence time, location and relative magnitude of the damage (micro-crack) in the specimen. The experimental results verified some precursors such as LURR (Load/Unload Response Ratio) and AER (Accelerating Energy Release) before macro-fracture of the samples. A new parameter, the correlation between the AE and the load, has been proposed to describe the loading history. On the eve of some strong earthquakes the correlation between the Benioff strain and the Coulomb failure stress (CFS) decreases, similar to the variation of LURR prior to strong earthquakes.  相似文献   

Orientation-based Continuum Damage Models for Rocks     

Xiaoyu Liu  Xiangchu Yin  Naigang Liang 《Pure and Applied Geophysics》2006,163(11-12):2529-2543

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Lamé parameters inversion based on elastic impedance and its application   总被引：1，自引：0，他引：1  

Wang Baoli  Yin Xingyao  Zhang Fanchang 《应用地球物理》2006,3(3):174-178

The Connolly (1999) elastic impedance (EI) equation is a function of P-wave velocity, S-wave velocity, density, and incidence angle. Conventional inversion methods based on this equation can only extract P-velocity, S-velocity, and density data directly and the elastic impedance at different incidence angles are not at the same scale, which makes comparison difficult. We propose a new elastic impedance equation based on the Gray et al. (1999) Zoeppritz approximation using Lamé parameters to address the conventional inversion method’s deficiencies. This equation has been normalized to unify the elastic impedance dimensions at different angles and used for inversion. Lamé parameters can be extracted directly from the elastic impedance data obtained from inversion using the linear relation between Lamé parameters and elastic impedance. The application example shows that the elastic parameters extracted using this new method are more stable and correct and can recover the reservoir information very well. The new method is an improvement on the conventional method based on Connolly’s equation. Wang Baoli graduated with a Bachelor’s degree in Prospecting Information and Engineering from the China University of Petroleum (East China) in 2004 and earned her Master’s degree from the department of Geophysical Prospecting and Information Technology in the China University of Petroleum ((East China) in 2006. She now studies for her PhD at the China University of Petroleum (East China). Her research interest is elastic impedance inversion.  相似文献