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1.
Based on the convection and diffusion mechanisms of radon migration, in this paper we deduce the two-dimensional differential equation for radon transportation in the overburden above active fault zones with an unlimited extension along the strike. Making use of the finite difference method, the radon concentration distribution in the overburden above active faults is calculated and modeled. The active fault zone parameters, such as the depth and the width of the fault zone, and the value of radon concentration, can be inverted from the measured radon concentration curve. These realize quantitative interpretation for radon concentration anomalies. The inversion results are in good agreement with the actual fault zone parameters. 相似文献
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E. M. Dmitriev 《Izvestiya Physics of the Solid Earth》2018,54(5):775-781
Radon-222 is inert radioactive gas with a half-life period of 3.8 days, it is a decay product of radium-226. Being escaped from minerals and underground waters into pore space of rocks and soil, it is transported to the surface by diffusion and advection and gone to the atmosphere. When modeling processes of atmosphere radon transport one sets value of radon flux from the surface, depending on contents of radium-226 in rocks and conditions of radon transport in soil, especially on soil porosity and humidity. The impact of radon turbulent transport in the atmospheric boundary layer (ABL) on radon flux density from the surface is estimated in this paper. It is shown that both for stationary state and for typical diurnal variations of the radon volumetric activity (VA) in the ABL, the correction to the radon flux density caused by its turbulent transport in the ABL is negligible (less than 1%) and doesn’t exceed measurement errors. Thus, when calculating radon VA in the ABL it is really possible to set an average value of the radon flux density on the surface as a boundary condition. 相似文献
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Summary Radon (Rn222) profiles were made over southwest Arizona from 300 m to 4km altitude. A temperature inversion near 2000 m and a stable radon concentration averaging 32.0 pc m–3 at 2000 m were characteristic of morning flights. At 300 m there was a definite pattern of high radon concentrations in the early morning and lower concentrations by noon. At 760 m the radon concentration increased between the times of ascent and descent. This pattern resulted from the trapping of radon close to the ground during stable night-time conditions and its subsequent upward dispersal with solar heating. The day-to-day variation in radon concentrations at higher levels cannot be attributed to local upward transport by diffusion but must have resulted from larger scale circulations. Above 2000 m there are no conclusive differences between morning, afternoon and evening profiles. Low concentrations of radon were measured during one late evening profile when there was definite subsidence and advection of drier air into the region. 相似文献
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Equations are proposed which describe the diffusion of a plume of oil from chemically dispersed oil slicks into the oceanic water column and which yield estimates of oil concentration as a function of the volume of oil dispersed, time-varying plume area, depth, time, and as a function of a single adjustable parameter, vertical diffusivity. A ‘diffusion floor’ at any desired depth may be included. Experimental data were fitted to the equations to yield an estimate of this diffusivity. It is concluded that oil concentrations can be estimated with a mean error of a factor of three, this high value being attributable to the inherently variable nature of the oceanic diffusion processes. Implications for assessing the toxic effects of dispersed slicks are discussed. It may be possible to calculate acute median lethal water depths and volumes for given organisms subjected to given dispersed oil slicks. 相似文献
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Radon-222 was measured using Kodak LR-115 film in the soils of 2500 locations near the Ngawha hot springs region, New Zealand, which is being exploited for geothermal power; the object was to determine its usefulness for predicting good drill sites. Unlike other surveys, which have shown large areas with consistent high radon values, anomalies here were scattered, and corresponded mainly with fault lineaments. The results suggested a major previously unnoticed fault. The sampling distance was 50 m.There was a strong seasonal effect on ground radon levels, with summer levels about ten times higher than winter levels.Swamps usually had measured radon levels of near zero because of the slow diffusion of radon in stagnant water, and even thermal areas (mainly in the swamps) usually had low measured values. However, where a fault crossed swamp it was sometimes detected, and with high signal/noise ratio, so swamps should be surveyed.Arguments from the radon levels found on different geologies show that at Ngawha radon has a maximum half value diffusion thickness of 7 m for lacustrine sediment and 25 m for basalt unless a permeable area is present (e.g., a fault).There was a weak correlation of radon levels with the temperatures found on drilling deep bores.Comparisons with the ROAC system and Alphacard system for measuring radon showed no statistical inter-correlations, but some qualitative correspondence of radon contours.The main strength of the method in regions with impermeable soils (such as at Ngawha), seems to be in detecting or confirming the presence of faults, and possibly (through them) indicating geological structure as deep as 300 m. 相似文献
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K. -K. Liu T. -F. Yui Y. -H. Yeh Y. -B. Tsai T. -L. Teng 《Pure and Applied Geophysics》1984,122(2-4):231-244
Radon (222Rn) concentration in geothermal waters and CO2-rich cold springwaters collected weekly in duplicate samples from four stations in northern Taiwan were measured from July 1980 to December 1983. Seven spike-like radon anomalies (increases of 2 to 3 times the standard deviation above the mean) were observed at three stations. Following every anomaly except one, an earthquake ofM
L
above 4.6 occurred within 4 to 51 days, at an epicentral distance 14 to 45 km, and at a focal depth of less than 10 km. The distribution of the earthquakes preceded by radon anomalies is skewed in certain directions from the radon stations; the radon stations seem to be insensitive to earthquakes occurring in the other directions. At the fourth station, near a volcanic area, much gas (mainly CO2) is discharged from the well, together with hot water. A very high concentration of radon was detected in the discharged gas; therefore trapping of gas in the water can result in anomalously high radon contents. According to limited measurements, the radon concentration in water appears to be undersaturated with respect to that in gas. This suggests that hot water is very susceptible to radon loss, and monitoring of radon in gas is more desirable. 相似文献
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应用气体扩散和氡蜕变理论讨论水氡异常的形成 总被引：2，自引：0，他引：2
应用气体扩散理论,给出水氡异常变民体积应变的近式关系式,式中证明由于气体的扩散效应,水氡异常变化对体积应变量相 放大作用。这有是形成异常的主要原因,同时结合丰水氡异常对其进行了探讨。 相似文献
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We have estimated the variations in the atmospheric electrostatic field (AEF, E
Z(0)) strength in the surface layer caused by variations in conductivity due to radon influences, cosmic ray intensity, changes
in the balance of light and heavy ions during sunset and sunrise, and under the effect of the ionospheric electric current
potential on the AEF potential. It is shown that the air conductivity varies due to ionization under the effect of radon emanations
and is determined by the radon exhalation and turbulent diffusion of the surface air layer, while the cosmic ray intensity
affects the surface air conductivity through changes in the ion recombination conditions. A decrease in the air conductivity
due to a decrease in the cosmic ray intensity (Forbush decrease) also decreases E
Z(0), while a decrease in radon fluxes results in an increase in E
Z(0). We have estimated the effect of illumination conditions on the AEF due to variations in the relative concentration of heavy
and light ions under the influence of photodetachment and photoattachment processes. The work has been done on the basis of
data received from the Paratunka observatory (Kamchatka). 相似文献
10.
The concentrations of222Rn and226Ra in the water column and in the sediments of Santa Barbara and San Nicolas Basins have been measured semi-annually over the last four years. Approximately one-third of excess radon profiles obtained in the water column in these basins can be adequately fit with a one-dimensional eddy diffusion-decay model. Exponential profiles in the center of San Nicolas Basin yield a vertical eddy diffusivity of 26±16 cm2/s and 3.4±1.0 cm2/s for Santa Barbara Basin. The application of a two-dimensional eddy diffusion-decay model to profiles obtained in the center and on the margins of San Nicolas Basin produces a better fit than is found using a one-dimensional vertical eddy diffusivity. The two-dimensional model for San Nicolas Basin predicts a vertical eddy diffusivity of 17 cm2/s and a horizontal eddy diffusivity of 105 cm2/s. These values are in reasonable agreement with those predicted from the vertical buoyancy gradient and the horizontal length scale.The vertically integrated radon excess (standing crop) in the water column of Santa Barbara Basin averages 53±23 atoms/m2 s. This is in good agreement with the flux across the sediment-water interface of 60±15 atoms/m2 s, calculated by measuring radon emanation in the sediments as a function of depth and applying a molecular diffusion-reaction model. Hence, one-dimensional molecular diffusion accurately predicts the flux of radon from the laminated Santa Barbara Basin sediments. In San Nicolas Basin the integrated radon excess in the water column is 376±143 atoms/m2 s, but the diffusive randon flux from San Nicolas Basin sediments averages only 190±53 atoms/m2 s. This descrepancy indicates that a non-diffusive process, probably macrofaunal irrigation, supplies much of the flux of radon from San Nicolas Basin sediments. 相似文献
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Yu. M. Mikhailov 《Izvestiya Physics of the Solid Earth》2007,43(4):336-339
The paper presents results of the analysis of occurrence times of earthquake precursors in a quasistatic electric field of the surface atmosphere on the Kamchatka Peninsula. The propagation velocity of the precursors and their occurrence time dependence on the earthquake source depth are estimated. A hypothesis on the possible correlation of the precursor propagation velocity with the diffusion rate of subsurface radon is proposed. 相似文献
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Constantin Cosma Botond Papp Mircea Moldovan Victor Cosma Ciprian Cindea Liviu Suciu Adelina Apostu 《Acta Geophysica》2010,58(5):947-956
Soil radon gas and/or its exhalation rate are used as indicators for some applications, such as uranium exploration, indoor
radon concentration, seismic activity, location of subsurface faults, etc., and also in the studies where the main interest
is the field verification of radon transport models. This work proposes a versatile method for the soil radon sampling using
a special manner of pumping. The soil gas is passed through a column of charcoal by using passive pumping. A plastic bottle
filled with water is coupled to an activated charcoal column and the flow of water through an adjustable hole made at the
bottom of bottle assures a controlled gas flow from the soil. The results obtained for the activity of activated charcoal
are in the range of 20–40 kBq/m3, for a depth of approximately 0.8 m. The results obtained by this method were confirmed by simultaneous measurements using
LUK 3C device for soil radon measurements. Possible applications for the estimation of radon soil potential are discussed. 相似文献
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Abhay Anand Bourai Sunita Aswal Anoop Dangwal Mukesh Rawat Mukesh Prasad Nagendra Prasad Naithani Veena Joshi Rakesh Chand Ramola 《Acta Geophysica》2013,61(4):950-957
Radon in the Earth’s crust or soil matrix is free to move only if its atoms find their way into pores or capillaries of the matrix. 222Rn atoms from solid mineral grains get into air, filling pores through emanation process. Then 222Rn enters into the atmosphere from air-filled pores by exhalation process. The estimation of radon flux from soil surface is an important parameter for determining the source term for radon concentration modeling. In the present investigation, radon fluxes and soil-gas radon concentration have been measured along and around the Main Central Thrust (MCT) in Uttarkashi district of Garhwal Himalaya, India, by using Scintillation Radon Monitor (SRM) and RAD7 devices, respectively. The soil radon gas concentration measured by RAD7 with soil probe at the constant depth was found to vary from 12 ± 3 to 2330 ± 48 Bq·m?3 with geometrical mean value of 302 ± 84 Bq·m?3. Th significance of this work is its usefulness from radiation protection point of view. 相似文献
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刘学领 《地震地磁观测与研究》2013,(5):188-192
对天津周良庄地热区不同含水层水化学背景开展实验研究,结果发现：随含水层埋藏深度加大,气体组分变化较大,水氡、水汞、离子组分变化较平稳,水氡背景值偏低.在此基础上,从含水层岩性、取样条件、水化学组分特性、地质构造等方面,对不同含水层之间水化学组分的差异性进行分析,认为区域内特殊地质构造是影响差异性的重要因素. 相似文献
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为使物理模拟实验效果与实际探测情形更为接近,在室外自然条件下建立中尺度土壤石油污染实验模型,油污染区扩展深度超过1 m,采用实地探测中常用的500 MHz雷达天线进行长期定时探测.通过实测雷达图像特征、土壤含水量含油量分析,并对比前人开展的小尺度室内模拟试验结果,综合评价探地雷达对油污染区的探测效果.研究表明探地雷达探测图像异常特征与污染区扩散阶段密切相关:包气带内油污染区会引起振幅增强;毛细带的油污染区则表现为水位面反射轴附近清晰可辨的高幅异常区,且水位面反射轴呈下凹状;随扩散过程持续进行,异常区下移与水位面反射轴相交,并产生水平扩张.当污染土含油饱和度大于20%时,可通过雷达图像异常区圈定污染范围;当污染土含油饱和度大于15%时,可通过频谱图出现低频响应的位置圈定污染区水平范围.中尺度实验结果与室内小尺度模拟结果具有一致性,可作为油污染区雷达图像异常的解译依据. 相似文献
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殿沟泉气氡浓度在汶川地震后经常出现成簇高频震荡异常。应用数据挖掘方法，采用正规化、聚类、特征值计算等方法对氡观测数据和地震目录进行预处理，提取气氡异常、震级、震源深度和地震分区等参数，在此基础上采用贝叶斯网络模型开展殿沟泉氡异常与周边区域地震活动统计关系研究。利用聚类开展的地震分区结果显示与构造分区基本吻合，反映出不同构造单元地震活动的丛集性特征；贝叶斯网络模型结果表明泉点气氡异常与周边地震活动有关，特别是与汶川地震主震区龙门山断裂中段和临近区青川断裂区域的地震活动有关。研究结果有助于了解泉点气氡对周边地震响应的差异性特征，对未来该泉点气氡异常的判断与地震预测有参考意义。为地震前兆异常分析和地震活动分区提供了一种新的技术思路和方法。 相似文献
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本文主要介绍1982年7月在甘肃永登黄土地层进行的160吨(TNT)爆破的土氡振动效应情况。观测到黄土地区爆破土氡具有显著的振动效应,各观测点出现的变化具有下列五点特征:(1)变化的普遍性;(2)变化形态的相似性;(3)空间展布的不均匀性;(4)时间上的突发性;(5)变化幅度随距离增长的衰减性。文中还对各种变化特征及有关的机制进行了初步的分析和讨论。 相似文献
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A. A. Spivak S. A. Kozhukhov M. V. Sukhorukov V. A. Kharlamov 《Izvestiya Physics of the Solid Earth》2009,45(2):118-133
The results of measurements of the volumetric activity of subsurface radon Rare given for several sections of the Earth’s crust located within the central part of the East European Platform. The influence of tectonic structures on the spatial zonality of radon emanation and the intensity of its temporal variations is shown. The temporal variations in radon emanation are characterized by periodicity with periods of approximately a day, as well as of 4, 14, and 29 days, and, as correlation analysis shows, they are determined by the cyclic recurrence of tidal deformations and by cyclonic processes in the atmosphere. The high correlation of the mean values of the volumetric activity of subsurface radon with the value of atmospheric pressure is established. The dependence of the volumetric activity of subsurface radon and its temporal variations on the depth within the range of depths 0.8–11.5 m is determined. As a result of laboratory experiments, the nonlinear nature of the dependence of radon emanation on the frequency of vibration action is established. For granites, the intensity of radon emanation is maximal at frequencies of 16 and 32 Hz. The results of complex measurements of the microseismic background and the volumetric activity of subsurface radon carried out in the region of the Nelidovo-Ryazan tectonic structure demonstrate the high correlation between the volumetric activity of subsurface radon and the relative amplitude of the quasi-monochromatic component of the microseismic background with a peak frequency of 16.5 Hz. 相似文献