土壤氡发射系数的研究
发布时间：2018-11-25 10:56
【摘要】：环境氡对人的危害问题越来越引起人们的关注,土壤氡是环境氡最主要的来源,而土壤氡发射系数又是评价土壤所致环境氡潜在风险的一个关键参数。本论文从土壤氡发射系数的测量及其影响因素两方面进行研究,希望建立一种具有很好稳定性和重现性的土壤氡发射系数的室内短时间累积测量方法,为高钍地区土壤氡发射系数的测量提供一种参考方法。研究氡发射系数与土壤基本物性之间的变化规律和相关程度,为我国土壤氡潜势填图以及采取防氡降氡措施提供一定基础数据和参考依据。以土壤为研究对象,根据氡从土壤中产生、析出及在密闭容器中累积的输运理论,推导氡发射系数短时间累积测量的数学计算公式。采用ALphaGUARD PQ2000测氡仪、集气瓶和抽滤瓶等装置,经过密封、导气、静置和测量等过程来测量土壤氡发射系数。通过对样品重复性测量和与长时间累积测量结果对比,分析短时间累积测量方法的稳定性、重现性以及可靠性。然后在此测量方法基础上,测量土壤在不同含水率、土壤颗粒粒径范围、镭活度浓度条件下的氡发射系数值,并对测量结果进行分析,研究氡发射系数与这些土壤基本物性之间的变化规律和相关程度。实测结果显示:在测量条件基本一致下,同一个样品重复测量结果的相对百分偏差在5%以内;短时间累积测量结果与长时间累积测量结果没有显著性差异;与土壤颗粒粒径和含水率之间的关系明显,在镭活度浓度和含水率相同下,氡发射系数随土壤颗粒粒径的增大而减少;在土壤颗粒粒径范围和镭活度浓度相同下,氡发射系数随土壤含水率的增加,表现为先增大而后减小的变化趋势,含水率为10%左右时近似是干燥情况下的2倍。综上所述,本论文研究建立了一种短时间累积测量土壤氡发射系数的方法,不仅提高了测量效率,还降低了测量过程中钍射气的影响,为高钍地区测量土壤氡发射系数提供了 一种新的参考方法。
[Abstract]:People pay more and more attention to the harm of environmental radon. Soil radon is the main source of environmental radon, and the coefficient of soil radon emission is a key parameter to evaluate the potential risk of environmental radon caused by soil. In this paper, the measurement of soil radon emission coefficient and its influencing factors are studied in order to establish an indoor short-time cumulative measurement method of soil radon emission coefficient with good stability and reproducibility. It provides a reference method for the measurement of radon emission coefficient in high thorium area. The change law and correlation degree between radon emission coefficient and soil basic physical properties are studied, which provides some basic data and reference for mapping radon potential and taking measures to prevent radon from radon reduction in China. Based on the transport theory of radon generation, exhalation and accumulation in a closed vessel, the mathematical calculation formula for the short time cumulative measurement of radon emission coefficient is derived. The radon emission coefficient of soil was measured by means of ALphaGUARD PQ2000 radon meter, gas collecting cylinder and filter bottle, through sealing, gas conduction, statics and measurement. The stability, reproducibility and reliability of the short time cumulative measurement method are analyzed by comparing the results of repeatability measurement and long time cumulative measurement. On the basis of this method, the radon emission coefficient of soil under different moisture content, particle size range and radium activity concentration is measured, and the results are analyzed. The variation and correlation between radon emission coefficient and the basic physical properties of these soils were studied. The measured results show that the relative percentage deviation of the repeated measurement results of the same sample is less than 5% under the same measuring conditions, and there is no significant difference between the short-term cumulative measurement results and the long-time cumulative measurement results. Under the same concentration of radium activity and water content, the radon emission coefficient decreases with the increase of soil particle size. Under the same particle size range and radium activity concentration, the radon emission coefficient increases first and then decreases with the increase of soil moisture content, and when the moisture content is about 10%, the radon emission coefficient is approximately twice as high as that under dry condition. To sum up, a method of measuring soil radon emission coefficient in a short period of time has been established in this paper, which not only improves the measurement efficiency, but also reduces the influence of thorium emission in the measurement process. It provides a new reference method for measuring radon emission coefficient in high thorium area.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R14
本文编号：2355846
[Abstract]:People pay more and more attention to the harm of environmental radon. Soil radon is the main source of environmental radon, and the coefficient of soil radon emission is a key parameter to evaluate the potential risk of environmental radon caused by soil. In this paper, the measurement of soil radon emission coefficient and its influencing factors are studied in order to establish an indoor short-time cumulative measurement method of soil radon emission coefficient with good stability and reproducibility. It provides a reference method for the measurement of radon emission coefficient in high thorium area. The change law and correlation degree between radon emission coefficient and soil basic physical properties are studied, which provides some basic data and reference for mapping radon potential and taking measures to prevent radon from radon reduction in China. Based on the transport theory of radon generation, exhalation and accumulation in a closed vessel, the mathematical calculation formula for the short time cumulative measurement of radon emission coefficient is derived. The radon emission coefficient of soil was measured by means of ALphaGUARD PQ2000 radon meter, gas collecting cylinder and filter bottle, through sealing, gas conduction, statics and measurement. The stability, reproducibility and reliability of the short time cumulative measurement method are analyzed by comparing the results of repeatability measurement and long time cumulative measurement. On the basis of this method, the radon emission coefficient of soil under different moisture content, particle size range and radium activity concentration is measured, and the results are analyzed. The variation and correlation between radon emission coefficient and the basic physical properties of these soils were studied. The measured results show that the relative percentage deviation of the repeated measurement results of the same sample is less than 5% under the same measuring conditions, and there is no significant difference between the short-term cumulative measurement results and the long-time cumulative measurement results. Under the same concentration of radium activity and water content, the radon emission coefficient decreases with the increase of soil particle size. Under the same particle size range and radium activity concentration, the radon emission coefficient increases first and then decreases with the increase of soil moisture content, and when the moisture content is about 10%, the radon emission coefficient is approximately twice as high as that under dry condition. To sum up, a method of measuring soil radon emission coefficient in a short period of time has been established in this paper, which not only improves the measurement efficiency, but also reduces the influence of thorium emission in the measurement process. It provides a new reference method for measuring radon emission coefficient in high thorium area.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R14
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