四川阿坝土壤与空气中氡气浓度及分布调查

采用IED-3000R轻便型测氡仪,对四川阿坝地区土壤、空气中的氡气浓度开展初步调查。结果表明：(1)测区空气中氡气浓度较高,均在平均值185 Bq/m3附近;(2)所测得土壤的氡气浓度范围为2 736～93 486 Bq/m3,平均值为26 021 Bq/m3,远远高于全国城市土壤中氡气浓度7 300 Bq/m3的平均值,同时在156个土壤氡气浓度被测点中共有91个测点氡气浓度值超过20 000 Bq/m3,而按照国家标准,对于民用建筑工程土壤中氡气浓度超过20 000 Bq/m3要进行不同程度的防氡工程;(3)地质环境、土壤松散度、岩土性质、土壤含水率为影响阿坝地区土壤氡气浓度的主要因素。     

主动瞬时活性炭吸附土壤氡气测量方法初探

研究了主动式活性炭吸附土壤氡气测量方法。在氡室条件下,利用设计的取样装置对主动式活性炭吸附法中活性炭吸附能力、取样量、取样速度等影响因素及测量参数开展了实验研究,并进行了该方法与其他3种不同土壤氡气测量方法的野外对比实验,相对于传统的被动式活性炭累积测氡,该方法工作效率高,为土壤氡气测量在勘探找矿、环境监测等领域的应用提供了一种全新的测量方式。     

泉州市、晋江市土壤中氡气浓度与地质背景的关系

通过泉州市、晋江市土壤中氡气测量,取得约465 km2土壤氡气环境调查成果,从结果来看,泉州市区和晋江市区土壤中氡气浓度普遍较低;市郊主要为山地,土壤中氡气浓度普遍较高;从土壤中氡气浓度水平的分布来看,土壤中氡气浓度水平主要与地质背景有关,二长花岗岩、钾长花岗岩、钾长浅粒岩及黑云片岩风化土壤中氡气浓度明显高于其他地质背景来源土壤.     

泉州市、晋江市土壤中氡气浓度与地质背景的关系

通过泉州市、晋江市土壤中氡气测量,取得约465 km2土壤氡气环境调查成果,从结果来看,泉州市区和晋江市区土壤中氡气浓度普遍较低;市郊主要为山地,土壤中氡气浓度普遍较高;从土壤中氡气浓度水平的分布来看,土壤中氡气浓度水平主要与地质背景有关,二长花岗岩、钾长花岗岩、钾长浅粒岩及黑云片岩风化土壤中氡气浓度明显高于其他地质背景来源土壤。     

土地开发利用中土壤氡气的检测与评价

对土地开发利用中土壤氡检测及其环境质量评价进行了探讨,提出了土壤氡气现场调查的技术要点,以氡浓度与表面氡析出率指标确定环境质量评价分级,并对相应的土地利用作了分析。     

断裂带土壤气测量方法在断层活动性研究中的应用——以嘉峪关断层为例

为了判断甘肃省嘉峪关断层监测点气氡浓度2015年6月以来的高值异常变化是否反映了嘉峪关断层活动的增强,本文基于土壤气跨断层分布规律,应用跨断层测量方法,通过多组分相关性分析及理论建模,综合分析了嘉峪关断层监测点气氡浓度高值异常变化与断层活动的关系。结果显示：监测点断层气中氡浓度快速增加期间,CO₂、CH₄和H₂的浓度没有增加,气氡与CO₂、CH₄浓度的变化不具正相关关系,表明监测点增加的氡气来源深部较浅,不代表断层活动的增强。监测点两侧跨断层测量结果表明,地表环境未改变一侧的氡气浓度符合断层气分布规律,地表环境发生改变一侧的氡气浓度不符合断层气分布规律,并且地表环境的改变时间与监测点气氡浓度异常变化时间同步。因此监测点气氡浓度的高值异常是由地表环境的改变引起的,嘉峪关断层的活动并没有增强。该方法为用断裂带土壤气体测量方法研究断层活动性的可靠性提供了思路。     

民用建筑工程中土壤氡浓度检测的实践

近年来,随着社会的不断发展,由于土壤氡元素污染引发的民用建筑内部环境污染问题在逐年增多,逐渐成为了影响群众身体健康的重要因素;氡是一种放射性气体,是危害人类身体健康的辐射源之一;氡经过衰变,形成一系列的带辐射微粒,当这些微粒被吸入肺部,部分会堆积聚集,并继续散发辐射,容易令吸入者患上肺癌。天然氡气的散发出自泥土、岩石或者黄岗岩制造的混凝土能建筑材料,从墙壁、地板、或经由地面上的裂缝进入建筑物的内部。由于部分建筑物通风不足,氡气会滞留堆积在房间内部;氡气的超标,则会对长期呆在室内的人们造成健康隐患,因此。对土壤中氡元素的检测变得越来越重要。     

缅甸拉泰-其培河段恩梅开江断裂带氡气测量

利用测量土壤中氡气异常来确定隐伏断裂的几何学特征。在缅甸拉泰—其培河段布置的四条测氡剖面中,氡气异常明显,拉泰-芒童段异常值约为本底值的3～8倍,芒童以南部分异常值比本底值高100倍,表明芒童以南地段活动性较强。氡气测量结果很好地控制了恩梅开江断裂在覆盖层之下的延伸展布方向。地表开挖及平硐揭露,很好地验证了测氡结果所推测的断层几何学特征。因此,测定土壤中氡气异常来寻找隐伏断裂的方法是可行的。     

一种区域性土壤氡危害的评价方法

在珠海地区测量土壤氡浓度和对应的表层土壤样品中的铀含量,用线性拟合的方法分析了氡与铀的关系.结果表明,土壤氡浓度和铀含量呈正相关关系,氡浓度大于20000Bq/m3的概率和铀含量有较好的线性关系.土壤氡浓度受多个因素的影响,测定值不稳定,故以其超标概率来表征更为科学.根据关系模型和风险分级标准,就可以快速进行区域土壤氡的危害评价.     

汶川地震震后大成都地区断裂带活动性氡气测量分析评价

本文运用活动断裂剖面上的土壤氡气浓度测量,对大成都地区断裂的位置、范围和活动性进行监测,监测结果表明汶川地震对大成都地区断裂带有较大的影响。通过对北川断裂虹口剖面、彭灌断裂小渔洞剖面、彭灌断裂中坝剖面、彭灌断裂白鹿剖面以及新津-蒲江断裂剖面进行监测,从测量结果分析可知:断裂剖面土壤氡浓度背景高于无断裂带地区,且受地震影响较大,距汶川地震震中越近,断裂剖面土壤氡浓度值越高;断裂剖面氡浓度异常阈值与背景值之比均不大于3,最大值与背景值之比均小于5。结合测量地点的地形、表层土壤结构等地质条件,对大成都地区震后活动断裂的相对活动性的强弱进行科学评价,认为目前大成都地区并无活动性极强的断裂,且北川断裂与新津-蒲江断裂的活动性高于彭灌断裂。     

Geotechnical reconnaissance and liquefaction analyses of a liquefaction site with silty fine sand in Southern Taiwan

Geotechnical reconnaissance of a recurrent liquefaction site at a Quaternary alluvial deposit in southern Taiwan was conducted to establish a comprehensive case history for liquefaction on silty fine sand with high fines content. The liquefaction occurred at a silty fine sand layer with D₅₀ = 0.09 mm and fines content greater than 35% and was triggered by a M_w = 6.4 earthquake on March 4, 2010, which induced maximum horizontal acceleration up to 0.189 g at the site. In situ subsurface characterizations, including standard penetration test, cone penetration test, and shear wave velocity measurement, were performed as well as cyclic simple shear tests on undisturbed specimens retrieved by a modified hydraulic piston sampler. Comparisons of cyclic resistance ratios (CRRs) indicate that CPT sounding with standard penetration rate could overestimate the resistance ratio and drainage conditions during penetration should be considered for high fines content soil in the liquefaction analysis. Additionally, variations of CRRs from different in situ tests indicate that correlations among in situ tests and CRR could be soil specific and precautions should be taken when using these curves on silty fine sands.     

Distribution and migration of lead in soil of Xiao River,Shijiazhuang, Hebei Province

The Xiao River sewage irrigation area in Luancheng where wastewater from Shijiazhuang flows through was taken as the research area. Five groundwater monitoring wells were set perpendicular to Xiao River, the research reveals the migration law and distribution characteristics of poisonous metal lead, through collecting and analyzing soil samples at different depths, investigating lithologic structure and pollution. The result shows that soil type has great impact on vertical lead distribution in aeration zone, which means that lead concentrates more in clay than in sand. Lead migrates fast in silty soil and silty clay, but slow in sand. The content of lead soil adsorbed decreases with grain size increasing. The most important factor influencing the distribution of lead is the soil type.     

北京平原区土壤氡地球化学特征分析

对北京平原区北西向和北东向两条氡浓度剖面进行了测量,发现北部地区氡背景值要大于南部,东向西方向氡浓度变化起伏频繁。分析其原因主要是受到土壤母质、地层以及断裂的影响,发现断裂是影响北京平原区氡浓度高值的主要因素。     

Observations of surface radon in Central Italy

Two years of in situ radon concentration measurements in the atmospheric surface layer have been collected in a central Italy town (L’Aquila), located in the Aterno river valley. These data have been analyzed in order to study the controlling mechanisms of surface radon abundance; observations of coincident meteorological parameters confirmed the role of dynamics on the local removal rate of this tracer. The relatively high negative correlation of hourly data of surface wind speed and radon activity concentration (R = −0.54, on annual scale) suggests that dynamical removal of radon is one of the most important controlling processes of the tracer accumulation in the atmospheric surface layer. An attempt is made to quantify the precipitation impact on radon soil fluxes. No anticorrelation of radon and precipitation comes out from the data (R = −0.15), as in previous studies. However, since the main physical parameter affecting the ground radon release is expected to be the soil accumulation of water, snow or ice, the emission flux has also been correlated with soil moisture; in this way a much clearer anticorrelation is found (R = −0.54).     

Spatial pore characteristics of unsaturated soils caused by dielectric geometric factors under permittivity method with 1 GHz frequency range

A dielectric measurement device called a frequency domain reflectometry (FDR) has been designed and constructed for the dielectric measurement of unsaturated soil consisting of a volumetric soil water content of about 0.1, 0.2, and 0.3 m³/m³ with different soil porosity around 0.40–0.45, respectively. The dielectric constant is measured in the frequency range 1 GHz. Soil calibration tests and tracer injection tests on standard sand and river sand are carried out in the laboratory. FDR measurement probes at different soil depths allow volumetric soil water content and dielectric constant measurements. The tracer concentration in the pore water is monitored by determining the dielectric constant, from the soil impedance. From the relationship between volumetric soil water content and dielectric constant, the specific calibration equations for the unsaturated soils were derived, and one can easily estimate the volumetric soil water content from the response of the measured dielectric constant for the soils. In the study of dielectric mixture models using α-value of 0.5 which is dielectric geometric factor, the effective porosity for the soils was computed to a range of 87–92% compared with the soil porosity.     

颗粒粒径对微生物固化砂土强度影响的试验研究

微生物固化技术（MICP）是岩土工程领域新兴起的一种不良地基处理技术,不同地基土体之间的颗粒粒径并不相同,其固化效果也可能存在一定差别。选用3种不同颗粒粒径范围的砂土进行微生物固化处理,并基于无侧限抗压强度试验、孔隙体积测量和洗酸处理,从宏观角度分析颗粒粒径对微生物固化效果的影响。结合扫描电镜测试,从细观角度对微生物固化机制进行了初探。研究结果表明,微生物固化砂土中碳酸钙晶体以颗粒簇形式堆积在砂土颗粒表面及颗粒间接触处,其尺寸随碳酸钙晶体堆叠程度的增加而增大;对于颗粒粒径较小的砂土,颗粒间孔隙较易被碳酸钙晶体填充密实,固化试样内有效碳酸钙晶体比例较大,“结构性”较强,无侧限抗压强度较高。     

对计算土壤和岩石中氡浓度及其表面析出率表面边界条件的讨论

本文对求解土壤或岩石中氡浓度及其表面析出率的边界条件进行了探讨。以空气中无穷远处氡浓度为零（空气中无氡源）的自然边界条件代替空气与土壤或岩石交界面氡浓度为零的边界条件,给出了土壤和岩石中氡浓度及其表面析出率的具体表达式。与前人研究结果比较,该式中增加了一项,表面氡析出率缩小了一个倍数。通过对土壤、岩石的具体计算．表明两种边界条件的计算结果有相当的偏差。同时,文中还讨论了在两类边界条件下对流对土壤或岩石中氡浓度及其表面析出率计算的影响。     

A comparison of field and laboratory analytical methods for radon site investigation

Soil-gas radon measurements provide a valuable tool in assessing probable indoor radon levels on a regional basis. However, in Great Britain, seasonal weather changes can cause large changes in soil-gas radon concentration. Although this does not significantly constrain systematic radon potential mapping programmes, it does cause difficulties in responding to ad-hoc requests for site-specific radon investigations. The relationship between soil-gas radon and gamma spectrometry measurements made in the field with radon released from a representative sample of soil in the laboratory has been investigated as part of a program to develop a method of radon potential mapping and site investigation which can be used at any time of the year. Multiple soil and soil-gas samples were collected from sites underlain by bedrocks with widely varying radon potentials. For each geological unit, sites both free of and covered by glacial drift deposits were sampled. Soil and soil-gas samples were taken at the same depth of 60–100 cm. The effectiveness of these radon site investigation procedures has been evaluated by studying the relationship between the soil-gas radon, gamma spectrometry and radon emanation data with an independent estimate of the radon risk. The geologic radon potential (GEORP), which is the proportion of existing dwellings which exceed the UK radon Action Level (200 Bq m⁻³) for a particular combination of solid and drift geology within a defined geographic area, has been used for this study as the independent estimate of radon risk. Soil-gas radon, radon emanation and eU (equivalent uranium by field γ spectrometry) are all good geochemical indicators of radon risk (GEORP) in Derbyshire but only soil-gas radon correlates significantly with GEORP in Northamptonshire. Radon in soil gas discriminates more effectively between sites with different radon potential in Northamptonshire if soil permeability is also taken into account. In general, measurement of soil-gas radon in the field provides the most universally applicable indicator of radon potential. If soil-gas radon concentrations cannot be determined because of climatic factors, for example when the soil profile is waterlogged, measurement of radon emanation in the laboratory or measurement of eU can be used as radon potential indicators in some geological environments. This applies particularly in areas where the soil composition rather than the composition and permeability of the underlying rock or superficial deposits are the dominant controls of radon potential. It appears, therefore, that it may be necessary to use different radon site investigation methods according to the specific factors controlling radon emanation from the ground. In some cases no method will provide a reliable indicator of radon risk under unfavourable climatic conditions.     

From radon hazard to risk prediction-based on geological maps,soil gas and indoor measurements in Germany

Mapped geological units can be regarded as proxies standing for a complex series of subsoil geochemical and physical properties including the assigned radon activity concentration in soil gas, which is taken as best estimator of the regional geogenic radon potential. Areal distribution of measuring sites for soil gas in Germany is adapted to spatial variation of geology. A grid-based and distance-weighted interpolation procedure is applied, following geologically defined neighbourhood relations of measuring sites and accounting for isolated outcrops of known geology but without measurements. To investigate the statistical relationship between indoor radon, house type and building ground specifications, measurements of the indoor radon concentration have been carried out in more than 10,000 dwellings in different regions of Germany. Multiple regression analyses of variance reveal that besides region-specific geological properties and building characteristics, various house type and living style variables significantly contribute to the explained variance for ground floor radon concentrations. These parameters are also dominant in controlling the radon transfer relation from soil gas to indoor air. Risk prediction maps for radon in houses indicating the probability to exceed certain indoor threshold values can be useful especially for regions with no or only a few measurements of indoor radon.