Migration and speciation transformation mechanisms of mercury in undercurrent zones of the Tongguan gold mining area,Shaanxi Loess Plateau and impact on the environment     

《China Geology》2021,4(2):311-328

In order to study the migration and transformation mechanism of Hg content and occurrence form in subsurface flow zone of gold mining area in Loess Plateau and its influence on water environment, the field in-situ infiltration test and laboratory test were carried out in three typical sections of river-side loess, alluvial and proluvial strata in Tongguan gold mining area of Shaanxi Province, and the following results were obtained: (1) The source of Hg in subsurface flow zone is mainly caused by mineral processing activities; (2) the subsurface flow zone in the study area is in alkaline environment, and the residual state, iron and manganese oxidation state, strong organic state and humic acid state of mercury in loess are equally divided in dry and oxidizing environment; mercury in river alluvial or diluvial strata is mainly concentrated in silt, tailings and clayey silt soil layer, and mercury has certain stability, and the form of mercury in loess is easier to transform than the other two media; (3) under the flooding condition, most of mercury is trapped in the silt layer in the undercurrent zone where the sand and silt layers alternate with each other and the river water and groundwater are disjointed, and the migration capacity of mercury is far less than that of loess layer and alluvial layer with close hydraulic connection; (4) infiltration at the flood level accelerates the migration of pollutants to the ground; (5) the soil in the undercurrent zone is overloaded and has seriously exceeded the standard. Although the groundwater monitoring results are safe this time, relevant enterprises or departments should continue to pay attention to improving the gold extraction process, especially vigorously rectify the small workshops for illegal gold extraction and the substandard discharge of the three wastes, and intensify efforts to solve the geological environmental problems of mines left over from history. At present, the occurrence form of mercury in the undercurrent zone is relatively stable, but the water and soil layers have been polluted. The risk of disjointed groundwater pollution can not be ignored while giving priority to the treatment of loess and river alluvial landform areas with close hydraulic links. The research results will provide a scientific basis for water conservancy departments to groundwater prevention and control in water-deficient areas of the Loess Plateau.  相似文献   

Design and application of a constant head well permeameter for shallow high saturated hydraulic conductivity soils     

R. W. Bell  N. J. Schofield 《水文研究》1990,4(4):327-342

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太阳常数的变化与太阳软x射线辐射流量及低频天波时延的关系   总被引：1，自引：0，他引：1  

王素琴  潘炼德 《时间频率学报》1998,21(1):49-53

本文对1982年在陕西临潼接收的美国罗兰-C西北大平洋链Y台发射的100kHz低频一跳天波时延的实测资料及SMS－GOES测量的太阳1～8A软x射线的每日辐射流量与SMM／ACRIMI测量的太阳常数之间的关系进行了分析。结果表明：太阳1～8A软x射线辐射流量与太阳常数之间存在较强的负相关;低频一跳天波时延与太阳常数之间存在着较强的正相关。并对此进行了讨论。  相似文献   

数字化地震遥测台网不间断供电系统研制     

刘民  梁永信 《东北地震研究》1997,13(3):49-57

本文介绍一种适用于数字化遥测地震台网的不间断供电系统，它具有交直流不间断切换，输出满足数据采集系统及数据传输设备所需的各种电压要求，并能对备份蓄电池自动恒流、恒压转换充电及过放电保护，冗余量大、可靠性高。解决了无人值守遥测地震台的供电问题。对其它数字设备也有广泛的应用价值。  相似文献   

Stress induced time dependent behavior of clayey soils     

Sudhir Kumar Tewatia  Pratima Rani Bose  Asuri Sridharan  Sunanda Rath 《Geotechnical and Geological Engineering》2007,25(2):239-255

It is shown that time compression curve obtained from one-dimensional consolidation curve in the laboratory may include six phases. These are initial compression, first primary compression, transition from first primary compression to second primary compression, second primary compression, and transition from second primary compression to creep and lastly creep. This paper attempts to identify the quantitative beginnings and characteristics of these phases. A mathematical characteristic of all the soils that follow primary consolidation as per Terzaghi’s one dimensional consolidation theory is derived. It is known as the constant of primary consolidation. It is used to study the beginning of secondary consolidation and its effects on primary consolidation. Another characteristic of soils for creep and total absence of primary compression is derived. Methods are suggested for the determination of coefficients of Primary and Secondary consolidations and the compression index.  相似文献   

Turbulent Kinetic Energy Dissipation in the Surface Layer     

D. Charuchittipan  J. D. Wilson 《Boundary-Layer Meteorology》2009,132(2):193-204

We estimated the turbulent kinetic energy (TKE) dissipation rate for thirty-two 1-h intervals of unstable stratification covering the stability range 0.12 ≤ −z/L ≤ 43 (z/L is the ratio of instrument height to the Obukhov length), by fitting Kolmogorov’s inertial subrange spectrum to streamwise spectra observed over a desert flat. Estimated values are compatible with the existence of local equilibrium, in that the TKE dissipation rate approximately equalled the sum of shear and buoyant production rates. Only in the neutral limit was the turbulent transport term in the TKE budget measured to be small.  相似文献   

Approximating constant‐Q seismic propagation in the time domain     

Tieyuan Zhu  José M. Carcione  Jerry M. Harris 《Geophysical Prospecting》2013,61(5):931-940

In this study, we investigate the accuracy of approximating constant‐Q wave propagation by series of Zener or standard linear solid (SLS) mechanisms. Modelling in viscoacoustic and viscoelastic media is implemented in the time domain using the finite‐difference (FD) method. The accuracy of numerical solutions is evaluated by comparison with the analytical solution in homogeneous media. We found that the FD solutions using three SLS relaxation mechanisms as well as a single SLS mechanism, with properly chosen relaxation times, are quite accurate for both weak and strong attenuation. Although the RMS errors of FD simulations using a single relaxation mechanism increase with increasing offset, especially for strong attenuation (Q = 20), the results are still acceptable for practical applications. The synthetic data of the Marmousi‐II model further illustrate that the single SLS mechanism, to model constant Q, is efficient and sufficiently accurate. Moreover, it benefits from less computational costs in computer time and memory.  相似文献   

地心和月心引力常数及月球形心与质心的确定   总被引：1，自引：0，他引：1  

孔祥元  李建成  郭际明  闫利 《大地测量与地球动力学》2006,26(2):109-114

指出了地心引力常数GMe、月心引力常数GMl及月球形状中心和月球质量中心的意义和重要性;介绍了用空间探测器观测数据测定GMe与GMl及月球形状中心和月球质量中心的原理和方法;综合给出了利用空间探测器测定的数值。  相似文献   

常Q滞弹性介质地震波动数值模拟——时域本构优化逼近          下载免费PDF全文

谢志南  郑永路  章旭斌 《地球物理学报》2018,61(10):4007-4020

在地震波动模拟中计入常Q滞弹性阻尼,可有效降低模拟波形的误差.就时域有限差分和有限元模拟而言,常基于广义标准线性体建立阻尼介质的时域本构逼近.广义标准线性体由若干标准线性体并联得到,增加标准线性体个数能有效提高模拟精度,但计算量及计算存储将成倍增长.目前尚未有普适的标准线性体个数优化取值方案.本文基于广义标准线性体参数的非线性优化拟合方法,详细分析了时域本构逼近误差的影响因素,清楚揭示了逼近误差仅取决于频带宽度,与频带上下限取值无关这一特性,阐明了构建具有普适性标准线性体个数优化取值方案的可行性.论证了波形模拟精度主要取决于波传播距离与模拟波长的比值以及标准线性体的个数取值.综合考虑上述两个控制因素,结合在波动正反演问题中广为采纳的波形时频误差衡量准则,对不同Q值介质给出了标准线性体个数优化取值表.进一步,本文提出采用不同个数标准线性体以近似不同Q值的阻尼介质时域本构,解决了以往波动数值模拟中统一采用相同个数标准线性体而导致的计算量及计算存储浪费或模拟精度低下等问题,并基于数值实验验证了这一方法的精度.本文工作对推进滞弹性介质波动数值模拟及其在全波形反演问题中的应用具有理论价值和实践意义.  相似文献   

新场岩体定压力压水试验数据解译方法的对比     

张明  季瑞利  苏锐  李杰彪  周志超 《国外铀金地质》2014,(1):32-38

以高放废物地质处置北山预选区新场岩体三个深钻孔的定压力压水试验为例,分别从压水阶段数据求解、压力恢复阶段数据求解和特殊试验段参数求解3个方面,对稳定流公式法和非稳定流参数拟合法进行了对比,得到了如下结论：非稳定流参数拟合法较稳定流公式法适用的渗流类型更多,使用数据量更大,结果更为可靠;在压水阶段和压力恢复阶段数据完整时,优先选择压力恢复阶段非稳定流参数拟合结果作为试验段的渗透系数.依据上述筛选原则,得到了新场岩体BS17～BS19三个深钻孔渗透系数的概率分布图,可初步判断新场岩体为低渗透性岩体,适宜于高放废物地质处置.  相似文献