【摘要】：環(huán)境氡對(duì)人的危害問題越來(lái)越引起人們的關(guān)注,土壤氡是環(huán)境氡最主要的來(lái)源,而土壤氡發(fā)射系數(shù)又是評(píng)價(jià)土壤所致環(huán)境氡潛在風(fēng)險(xiǎn)的一個(gè)關(guān)鍵參數(shù)。本論文從土壤氡發(fā)射系數(shù)的測(cè)量及其影響因素兩方面進(jìn)行研究,希望建立一種具有很好穩(wěn)定性和重現(xiàn)性的土壤氡發(fā)射系數(shù)的室內(nèi)短時(shí)間累積測(cè)量方法,為高釷地區(qū)土壤氡發(fā)射系數(shù)的測(cè)量提供一種參考方法。研究氡發(fā)射系數(shù)與土壤基本物性之間的變化規(guī)律和相關(guān)程度,為我國(guó)土壤氡潛勢(shì)填圖以及采取防氡降氡措施提供一定基礎(chǔ)數(shù)據(jù)和參考依據(jù)。以土壤為研究對(duì)象,根據(jù)氡從土壤中產(chǎn)生、析出及在密閉容器中累積的輸運(yùn)理論,推導(dǎo)氡發(fā)射系數(shù)短時(shí)間累積測(cè)量的數(shù)學(xué)計(jì)算公式。采用ALphaGUARD PQ2000測(cè)氡儀、集氣瓶和抽濾瓶等裝置,經(jīng)過密封、導(dǎo)氣、靜置和測(cè)量等過程來(lái)測(cè)量土壤氡發(fā)射系數(shù)。通過對(duì)樣品重復(fù)性測(cè)量和與長(zhǎng)時(shí)間累積測(cè)量結(jié)果對(duì)比,分析短時(shí)間累積測(cè)量方法的穩(wěn)定性、重現(xiàn)性以及可靠性。然后在此測(cè)量方法基礎(chǔ)上,測(cè)量土壤在不同含水率、土壤顆粒粒徑范圍、鐳活度濃度條件下的氡發(fā)射系數(shù)值,并對(duì)測(cè)量結(jié)果進(jìn)行分析,研究氡發(fā)射系數(shù)與這些土壤基本物性之間的變化規(guī)律和相關(guān)程度。實(shí)測(cè)結(jié)果顯示:在測(cè)量條件基本一致下,同一個(gè)樣品重復(fù)測(cè)量結(jié)果的相對(duì)百分偏差在5%以內(nèi);短時(shí)間累積測(cè)量結(jié)果與長(zhǎng)時(shí)間累積測(cè)量結(jié)果沒有顯著性差異;與土壤顆粒粒徑和含水率之間的關(guān)系明顯,在鐳活度濃度和含水率相同下,氡發(fā)射系數(shù)隨土壤顆粒粒徑的增大而減少;在土壤顆粒粒徑范圍和鐳活度濃度相同下,氡發(fā)射系數(shù)隨土壤含水率的增加,表現(xiàn)為先增大而后減小的變化趨勢(shì),含水率為10%左右時(shí)近似是干燥情況下的2倍。綜上所述,本論文研究建立了一種短時(shí)間累積測(cè)量土壤氡發(fā)射系數(shù)的方法,不僅提高了測(cè)量效率,還降低了測(cè)量過程中釷射氣的影響,為高釷地區(qū)測(cè)量土壤氡發(fā)射系數(shù)提供了 一種新的參考方法。
[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.
【學(xué)位授予單位】：中國(guó)地質(zhì)大學(xué)(北京)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：R14

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本文編號(hào)：2355846