Oural C R, Upchurch S B, Brooker H R
Department of Physics, University of South Florida, Tampa 33620.
Health Phys. 1988 Dec;55(6):889-94. doi: 10.1097/00004032-198812000-00004.
Gross-alpha radiation data from ground water samples are subject to variability introduced as a result of analytical procedure. For example, ground water in the surficial aquifer of central Florida commonly has gross-alpha radioactivity in excess of 555 Bq m-3 (15 pCi L-1). This activity, commonly unsupported by Ra, often results from the 222Rn progeny. The relatively short-lived daughters of 222Rn can give rise to variations in gross-alpha measurements of up to 2 orders of magnitude in replicate samples. Polonium-210, a longer-lived Rn daughter, is also found in concentrations greater than predicted by the Ra content. As a consequence, it is suggested that gross-alpha measurements include Po analyses with Ra and U when standards are exceeded. It should be recognized that, depending on the activity of 210Pb, 210Po activity may vary significantly with holding time. Variations of measured Po activity in replicate samples collected and prepared by present methods indicate that Po analyses may be inconsistent and frequently underestimate total Po activity. Sample preparation methods and measurement techniques are discussed which greatly improve the overall accuracy and consistency of gross-alpha and Po analyses.
来自地下水样本的总α辐射数据会因分析程序而产生变化。例如，佛罗里达州中部浅层含水层中的地下水通常总α放射性超过555 Bq m-3（15 pCi L-1）。这种放射性通常没有镭的支持，往往是由222Rn子体造成的。222Rn相对短寿命的子体可导致重复样本中总α测量值变化高达2个数量级。钋-210是一种寿命较长的Rn子体，其浓度也高于根据镭含量预测的浓度。因此，建议当超过标准时，总α测量应包括对镭和铀以及钋的分析。应该认识到，根据210Pb的放射性，210Po的放射性可能会随保存时间而显著变化。用现有方法采集和制备的重复样本中测量的钋放射性变化表明，钋分析可能不一致，并且经常低估总钋放射性。文中讨论了样本制备方法和测量技术，这些方法和技术大大提高了总α和钋分析的整体准确性和一致性。
