夏垫活动断裂CO_2、Rn、Hg脱气对环境的影响

为明确夏垫活动断裂排气的环境效应,采用土壤气测量方法,连续3年对北京东北部的夏垫活动断裂带CO_2、Rn和Hg的脱气浓度及通量进行重复原位测量,并计算了CO_2和Hg脱气对大气的年贡献量。结果表明,夏垫断裂土壤气浓度及通量的最大值出现在三河平谷大地震震中附近的潘各庄与齐心庄测区。潘各庄剖面土壤气中Rn、CO_2浓度异常明显,与震中附近岩体构造裂隙更发育有关,表明三河-平谷大地震对夏垫断裂脱气具有促进作用。夏垫活动断裂带通过脱气作用每年向大气排放CO_2约0.23 Mt、Hg约1.3 kg。其中,CO_2浓度较低,无窒息风险,部分测点Hg浓度高于18.32 ng/m~3,属一般程度污染,大东关、潘各庄部分测点Rn浓度高于50 k Bq/m~3,需对附近建筑物采取综合防氡措施。     

玉树Ms7.1级地震甘达村段构造地球化学特征

为探究地震对断层带气体逸出的影响和震后气体地球化学特征随时间的变化,以及地震动力学特征,利用土壤气地球化学方法,于2010年4月14日青海玉树Ms7.1级地震断层甘达村段测量地表破裂特征和震后断层气氡和汞浓度,发现断层带土壤的气氡和汞浓度的平均值分别为9246 Bq/m3和4.2 ng/m3。破裂带中Rn浓度变化幅度大,而Hg的浓度变化较小。断层主滑面附近Rn浓度相对降低,为地表破裂后断层气逃逸所致。泉水气氡观测发现,震前氡浓度增高,表明地震断层活动性增强。因此巴颜喀拉地块向东不均匀挤压,使深部气体沿地震断裂逃逸至地表,这也是造成断层带气氡、汞浓度的增高的原因。     

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。     

云南禄劝县皎西乡土壤氡测量在易门-罗茨隐伏断裂研究中的应用

易门-罗茨断裂带是多期活动的大规模断裂带,以易门-罗茨断裂为主断裂。在禄劝县皎西一带,断裂带控制了南北向的串珠状第四系盆地,盆地内第四纪沉积物厚数米至数十米,主要的控盆隐伏断裂位置、特征难以确定。采用地质调查与土壤氡测量相结合的方法,查明了区内控盆隐伏断裂的位置、产状、宽度等。调查结果与地貌和区域构造特征吻合较好,因此认为,土壤氡测量适用于山间盆地内隐伏活动断裂的调查。     

天津市宁河县土壤氡含量与断裂构造的耦合关系初探

利用MT和EH4大地电磁测深的方法，在对天津市宁河县的断裂构造格局进行了新一轮的探测后，结合前人航磁、重力、电法和地震等资料，重新确定了该地区的断裂构造格架。为了进一步掌握断层的确切位置，笔者利用FD-3017镭A测氡仪对断裂带及其附近位置的土壤氡含量进行了测量，发现在厚大的第四系覆盖地区，土壤氡含量对断裂构造的反应敏感，断裂带正上方氡含量最高。该方法具有实用推广价值。     

海原断裂带土壤气与地下水地球化学特征研究

选取海原断裂带曹洼(CW)、菜园(CY)、万家水(WJ)、水泉(SQ)、三塘(ST)、松山(SS)和安远(AY)7个测区进行土壤气测量与地下水地球化学检测,依据海原断裂带不同构造部位的土壤气浓度、水化学组分和同位素组成等,分析了海原断裂带的构造活动性分段特征。结果显示：研究区内土壤气Rn释放量较高的区域主要集中于ST、SQ测区,且断裂带中部区域气氡浓度相对较低;氦浓度及其同位素检测结果表明ST、SQ和CY测区土壤逸出气中含有幔源气体;泉水化学组分及氢氧同位素分析结果显示SQ和ST测区地下水与围岩介质之间的水岩相互作用程度较高、水岩反应平衡状态较高、地下水循环深度较大;泉水氚活度分析结果显示水泉（SQ）测区地下水补给区较远、水循环周期较长、新老水体的交换作用缓慢。综合分析认为,相比其他区段,海原断裂中西段（SQ ST）接近1920年8.5级地震破裂段,其断裂带闭锁程度较弱、与地壳深部的连通性较好,更有利于地下流体的扩散与运移。     

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。     

土壤氡浓度日变化影响因素研究

地表壤氡可以反映地下深部的水文、地质、矿产、热源等信息,但土壤氡浓度有年变和日变的特点。为了研究土壤氡浓度日变化规律及其影响因素,采用α能谱测氡仪对土壤氡进行连续测量。结果表明:土壤氡浓度呈单峰型日变化特征,最大值出现在19:00~22:00,最小值出现在11:00~14:00,土壤温度是影响土壤氡浓度的关键因子,土壤氡浓度与土壤温度呈正相关。降雨对土壤氡浓度有显著的影响,降雨后土壤氡浓度出现双峰型日变化特征,其变化与土壤湿度和空气温度等气象因素有关。     

北京平原区隐伏断裂与氡浓度响应关系

北京地区隐伏断裂发育,NW及NE向断裂相互交汇,成为未来可能发生地震的构造.为了研究活动断裂与土壤氡浓度的响应关系,本次对北京平原区NW和NE向2条剖面进行了氡浓度测量.通过测试分析,基本查明了隐伏构造与土壤氡浓度的对应关系以及影响土壤氡浓度的相关地质因素.研究表明,活动断裂存在的区域氡浓度明显高于周边区域,且在构造复...     

基于土壤氡气测量识别甘肃北山南缘隐伏断裂

我国高放废物地质处置库首选预选区位于甘肃北山南缘，区内分布有多条大型非活动断裂构造，这些断裂很可能成为未来放射性核素迁移的主要通道。断裂在向地表延伸过程中，受第四系覆盖等因素影响，造成关键构造部位隐伏地下而难以识别。本文以北山地区新场地段南部红旗山和前红泉断裂为研究对象，采用土壤中氡气测量方法，探讨了大型断裂构造中隐伏段落的识别及其指示的水文地质意义。结果表明：土壤中氡气测量对于识别北山南缘隐伏断裂具有很好的指示意义，是传统地质调查方法的一种重要补充；红旗山和前红泉断裂裂隙系统整体开启性均较差，裂隙系统不发育，影响范围较小，不具备形成较大规模储水空间的可能性。不同断裂带土壤氡浓度背景值差异较大，可根据土壤氡浓度累积频率分布图确定背景值；土壤氡浓度等值线分布图对判断隐伏断裂位置具有一定的指示作用。对于压剪性断裂而言，主断裂多沿氡气高异常与低异常边界分布或表现为氡气中等异常，而两侧的次级断裂表现为氡气高异常。     

扬州市地质构造背景与氡浓度之间关系分析

本文通过对扬州市区地层岩性、地质构造、断裂及放射性元素氡的特性分析,阐明了地区地层岩性、地质构造、断裂与放射性元素氡的形成和运移之间存在的关系,为地区建设工程氡浓度检测与控制提供依据。     

煤层采动裂隙与氡气浓度相关性研究

煤层的开采极易导致采动裂隙直接连通地表,引起煤层自燃、地下水流失等灾害现象.掌握煤层上表岩层中裂隙发育特征,是解决上述问题的基础.将氡测量技术引入到煤炭采动裂隙发育研究中,通过实验模型模拟,分析得出了沙基型煤层采动裂隙分布与氡气浓度之间的相关规律.     

Impact of geohydrology and neotectonic activity on radon concentration in groundwater of intermontane Doon Valley, Outer Himalaya, India

 Radon concentration was measured in 133 water samples from tubewells, handpumps, dug wells and springs of the Doon Valley, Outer Himalaya, India. The observed radon values were found to vary from 10 to 154 Bq/l whereas radium in selected water samples varied from 0.11 to 0.75 Bq/l. Three different clusters of high radon values were observed in the north-western, central and south-eastern parts of the Doon Valley. These clusters were found to be associated with tectonics (thrust/fault) and associated uranium mineralization in the area. In general, radon concentration in groundwater was found to be positively correlated with the depth of the wells, whereas no significant correlation was observed between radon concentration in groundwater and the water temperature, pH value, conductivity and altitude of the water samples. An attempt has also been made to determine the nature and extent of aquifers in the Doon Valley on radon concentration in groundwater. The variation in radon concentration within the groundwater of the study area was found to be controlled by the neotectonic activity and geohydrological processes that occur in the area. The impact of these activities on radon concentration in groundwater are discussed. Received: 17 September 1999 · Accepted: 11 April 2000     

Spatial association between residential radon concentration and bedrock types in New Hampshire

Using a large database of residential short-term radon measurements in New Hampshire, this study evaluated the ability of expert-assigned bedrock radon potential for predicting residential radon concentration. First, each bedrock type was assigned a radon potential level by a geologist familiar with the local geology. Then, using residential radon measurements, a continuous surface of radon concentration was generated through a kriging process. The mean residential radon concentration within the spatial extent of each bedrock type was then calculated based on that surface. The Spearman Rank Correlation Coefficient was calculated between the two ranks of the bedrock types, one based on the expert-assigned potential level and the other based on the mean residential concentration. A strong correlation between the rank correlation and the area of the bedrock type was found. When only the 15 largest bedrock types were used, the Spearman Correlation Coefficient reached 0.6. Geological knowledge is concluded to be useful in predicting and mapping residential radon concentration, but the prediction should be interpreted with caution, especially for areas in which the underlying bedrocks are highly localized.     

A preliminary design of a radon potential map for Canada: a multi-tier approach

Canada is a vast country with most of the population living on a small portion of the land. However, for a national radon potential map, it is mandatory to cover the entire country including sparsely populated areas. Because of these characteristics, the radon map development for Canada is challenging. After briefly reviewing of radon map development in the world, this study considers a multi-tier approach to best use available however limited resources and to generate a national radon map in a timely fashion. In summary, radon potential maps for highly populated areas should be determined by direct indoor radon measurements where enough indoor radon data are available. In areas where indoor radon measurements are limited or not yet available, the radon potential maps could be developed from various data sources with a multi-factor scoring system including geological information on soil permeability, soil gas radon concentration and ground uranium concentration. In sparsely populated areas, radon potential maps can only be generated with geological predictive tools, especially in those areas where no houses have yet been built. Because indoor radon measurement data and geological information relevant to radon are very limited in Canada, a multi-step strategy is also worth considering in addition to the multi-tier approach.     

活性炭法测定室内外环境中氡的吸附饱和性实验

介绍了一套实验装置,可通过该装置了解吸附了氡气的活性炭的放射性计数与活性炭所在环境的氡浓度的关系。活性炭中氡或其衰变子体放出的γ射线的总计数与氡浓度成线性关系;γ射线的总计数经过校正后,可以换算成活性炭所在环境的氡浓度。     

深圳市环境放射性异常带识别与影响因素分析

在环境放射性调查的基础上,结合地质环境特征分析,对深圳市环境放射性异常带进行识别,并对相关影响因素进行分析。研究结果表明,沿NE、NW向断裂带附近土壤氡活度浓度和花岗岩出露区岩石放射性核素含量较高,根据分析结果,识别出深圳市范围内主要有3条放射性异常带。     

Reliability of inexpensive charcoal and alpha-track radon monitors

A comparison between single short-term radon measurements and annual radon measurements in basements shows that significant uncertainties should be associated with the short-term measurements. Activated charcoal radon monitors which measure radon over a 3 to 7 day interval yield measurements that should carry a ± 90% uncertainty in terms of estimating annual radon concentration. Alpha-track radon monitors which measure radon over a 3 month interval should carry a ± 30% uncertainty. Decisions about home purchases, home remediation and the development of risk characterizations may often be incorrect if currently popular but unrealistically low estimates of uncertainty are applied to short-term radon measurements. Optimal results are obtained from year-long alpha-track measurements.     

土壤中氡浓度检测及其影响因素

综合相关文献研究,通过工程实例介绍土壤中氡气浓度的检测方法,对检测结果进行统计学分析,根据分析结果探讨不同土壤中氡浓度差异及其影响因素。结果显示:土壤孔隙度是影响土壤中氡气浓度的关键因素。不同类型的表层土壤,孔隙度不同,所含氡气浓度也不同。当表层土壤为房渣土、填土时,土质夯实,孔隙率低,氡浓度含量较低;表层土壤为粉土、粉质粘土时,土质较均匀,土层较疏松,孔隙度略大,土壤氡浓度大于前者;表层土壤为粉砂、细砂时,土层更为疏松,土壤中孔隙度再次增大,氡在土壤中有大量的存储空间,所含的氡浓度最大。因此,土壤的孔隙度大小影响氡从地下向地表渗透析出的难易程度,孔隙度越大氡越容易渗透其中,浓度就越高。