土壤氡析出率影响因素及估算模型

Discussion of influencing factors on the radon exhalation rate and theoretical model

目的通过对某定点处土壤氡析出率的长期测量观察,分析并总结环境因素对氡析出率的影响规律。方法使用ERS-2静电收集式氡采样测量仪,每次采样累积时间40min,每10分钟测量一次氡浓度,通过线性拟和求算出土壤表面氡析出率;利用已有的数学模型对测量结果进行估算和评价;同时测量环境空气的湿度、温度、土壤含水量和土壤氡浓度。结果春季土壤氡析出率平均值为(24·9±5·6)mBq/(m2·s),夏季平均值为(11·9±3·4)mBq/(m2·s)。结论在影响土壤氡析出率的诸因素中,湿度非常重要,而环境温度对氡析出率的影响相对较小;测量期间环境气压变化不明显,没有观测到气压对析出率的影响。开展土壤射气系数的研究,将有助于阐明多种环境因素对土壤表面氡析出率的影响。

Objective Long term continuous measurements of radon exhalation were conducted at one site in order to clarify the contribution of the environmental factors. Methods The radon concentration was measured by ERS-2 Electrostatic-Radon/Thoron-Sampler in 40 minutes. The sampler monitored the concentration at intervals of 10 minutes. The radon exhalation rate was determined by the linear increase of the concentration. The result was estimated with a theoretical model. At the same time, the temperature, barometric pressure, and the humidity of the soil and air are measured. Results The exhalation rate of radon is （24.9 ± 5.6） mBq/（m^2 ^s） in spring and （11.9 ± 3.4） mBq/（m^2 ·s） in summer while the humidity of the soil and air in summer are markedly higher than that in spring. Conclusions The main influencing factor on the variation of exhalation rate is the humidity. The influence of temperature and barometric pressure was not observed. It will make the mechanism for radon exhalation more clear to study the emanation power of soil.