Radon-222 exhalation from open ground on and around a uranium mine in the wet-dry tropics
Radon-222 exhalation from open ground on and around a uranium mine in the wet-dry tropics
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DOI：
10.1016/j.jenvrad.2008.09.003
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发表时间：
2009-01-01
影响因子：
2.3
通讯作者：
Martin, Paul
中科院分区：
文献类型：
--
作者：
Lawrence, Cameron E.;Akber, Riaz A.;Martin, Paul
地表呼出的氡气 222 取决于许多变量，例如 (226)Ra 活性浓度及其在土壤颗粒中的分布；土壤颗粒大小；土壤孔隙度、温度和湿度；大气压力、降雨量和温度。在这项研究中，对澳大利亚北部 Ranger 铀矿内部和周围的 (222)Rn 呼出通量密度进行了测量，以研究这些变量在热带地区的影响。在废石堆、矿石堆、矿坑、在陆地上喷灌高 (226)Ra 浓度的废水的地点以及矿井外的地点进行了测量。所选地点代表了从含铀岩石到周围土壤的各种地貌区域。一般来说，雨季降雨减少了 (222)Rn 呼气，但在一些地点，降雨的开始导致呼气通量密度逐步上升。结果表明，(226)Ra活度浓度、土壤粒径和土壤孔隙度等参数对(222)Rn通量密度有显着影响。对于类似的地貌地点，(226)Ra 活性浓度是主导因素，但土壤粒度和孔隙度也会影响 (222)Rn 呼出。有植被的表面比贫瘠的表面表现出更高的呼气通量密度，这可能是因为相关的根部结构增加了土壤孔隙度和保湿性。在八个地点一年多的重复测量能够分析降水和土壤湿度对 (222)Rn 呼气的影响。土壤湿度深度剖面在不同季节和雨季不同时间都有变化，这表明持续时间、强度和降水事件之间的时间等因素对 (222)Rn 通量密度有很大影响。 (c) 2009 Elsevier Ltd. 保留所有权利。
Radon-222 exhalation from the ground surface depends upon a number of variables such as the (226)Ra activity concentration and its distribution in soil grains; soil grain size; soil porosity, temperature and moisture; atmospheric pressure, rainfall and temperature. In this study, (222)Rn exhalation flux density measurements within and around the Ranger uranium mine in northern Australia were performed to investigate the effect of these variables within a tropical region.Measurements were taken at the waste rock dumps, ore stockpiles, mine pits, and at sites where effluent water with elevated (226)Ra concentration has been spray irrigated over land, as well as at sites outside the mine. The sites selected represented a variety of geomorphic regions ranging from uranium-bearing rocks to ambient soils. Generally, wet season rains reduced (222)Rn exhalation but at a few sites the onset of rains caused a step rise in exhalation flux densities. The results show that parameters such as (226)Ra activity concentration, soil grain size and soil porosity have a marked effect on (222)Rn flux densities. For similar geomorphic sites, (226)Ra activity concentration is a dominant factor, but soil grain size and porosity also influence (222)Rn exhalation. Surfaces with vegetation showed higher exhalation flux densities than their barren counterparts, perhaps because the associated root structure increases soil porosity and moisture retention.Repeated measurements over one year at eight sites enabled an analysis of precipitation and soil moisture effects on (222)Rn exhalation. Soil moisture depth profiles varied both between seasons and at different times during the wet season, indicating that factors such as duration, intensity and time between precipitation events car, influence (222)Rn flux densities considerably. (c) 2009 Elsevier Ltd. All rights reserved.