“…For example, in Fig. 5 the values of TS for our samples are significantly lower than previously reported, and 2.3 ± 0.2 times lower for our rock samples compared with Lee et al (2010) for a single sample, and 2.0 ± 0.3 times lower for our soil samples compared with Markkanen and Arvela (1992) and Iskandar et al (2004), who both used several soil samples. Note, however, that in our study we have measured EC Ra from a larger number of rock and soil samples and over a wider range of EC Ra values but with a narrower temperature range than in these three previous studies (Table 1).…”
Section: Discussioncontrasting
confidence: 62%
“…This method has the advantage of keeping the same sample for each individual estimate of TS, and to allow examining the TS for each sample separately, but does The two TS values are labelled in: a refers to the first method and b refers to the second method as described in the text. (Markkanen and Arvela, 1992;Iskandar et al, 2004;Lee et al, 2010) are also plotted for comparison (dashed lines).…”
Section: Resultsmentioning
confidence: 99%
“…It was also recognized long ago using concrete samples (Gabrysh and Davis, 1955;Auxier et al, 1974;Ingersoll, 1983) and identified to be less pronounced than the effect of water content (Auxier et al, 1974;Stranden et al, 1984;Markkanen and Arvela, 1992). Nevertheless, the size of the temperature effect investigated by a few workers with a few samples only (Iskandar et al, 2004;Lee et al, 2010), remains unclear. Reported values of temperature sensitivity vary from 0.7 % • C −1 to 1.5 % • C −1 for soil samples (Markkanen and Arvela, 1992) and from 1 % • C −1 to more than 4 % • C −1 for rock samples (Stranden et al, 1984).…”
Abstract. Temporal variations of radon concentration, or spatial variations around geothermal systems, are partly driven by the effect of temperature on the radon source term, the effective radium concentration (EC Ra ). EC Ra from 12 crushed rock and 12 soil samples from Nepal was measured in the laboratory using the radon accumulation method and Lucas scintillation flasks at three temperatures: 7, 22 and 37 • C. For each sample and at each temperature, 5 or 6 measurements were carried out, representing a total of 360 measurements, with an EC Ra average varying from 1.1 to 75 Bq kg −1 . While the effect is small, EC Ra was observed to increase with temperature in a significant and sufficiently reproducible manner. The increase was approximately linear with a slope (temperature sensitivity, TS) expressed in % • C −1 . We observed a large heterogeneity of TS with average values (range min-max) of 0.79 ± 0.05 (0.16-2.0) % • C −1 and 0.61 ± 0.05 (0.10-2.0) % • C −1 , for rock and soil samples, respectively. While this range overlaps with the results of previous studies, our values of TS tend to be smaller. The observed heterogeneity implies that the TS, rather poorly understood, needs to be assessed by dedicated experiments in every case where it is of consequence for the interpretation.
“…For example, in Fig. 5 the values of TS for our samples are significantly lower than previously reported, and 2.3 ± 0.2 times lower for our rock samples compared with Lee et al (2010) for a single sample, and 2.0 ± 0.3 times lower for our soil samples compared with Markkanen and Arvela (1992) and Iskandar et al (2004), who both used several soil samples. Note, however, that in our study we have measured EC Ra from a larger number of rock and soil samples and over a wider range of EC Ra values but with a narrower temperature range than in these three previous studies (Table 1).…”
Section: Discussioncontrasting
confidence: 62%
“…This method has the advantage of keeping the same sample for each individual estimate of TS, and to allow examining the TS for each sample separately, but does The two TS values are labelled in: a refers to the first method and b refers to the second method as described in the text. (Markkanen and Arvela, 1992;Iskandar et al, 2004;Lee et al, 2010) are also plotted for comparison (dashed lines).…”
Section: Resultsmentioning
confidence: 99%
“…It was also recognized long ago using concrete samples (Gabrysh and Davis, 1955;Auxier et al, 1974;Ingersoll, 1983) and identified to be less pronounced than the effect of water content (Auxier et al, 1974;Stranden et al, 1984;Markkanen and Arvela, 1992). Nevertheless, the size of the temperature effect investigated by a few workers with a few samples only (Iskandar et al, 2004;Lee et al, 2010), remains unclear. Reported values of temperature sensitivity vary from 0.7 % • C −1 to 1.5 % • C −1 for soil samples (Markkanen and Arvela, 1992) and from 1 % • C −1 to more than 4 % • C −1 for rock samples (Stranden et al, 1984).…”
Abstract. Temporal variations of radon concentration, or spatial variations around geothermal systems, are partly driven by the effect of temperature on the radon source term, the effective radium concentration (EC Ra ). EC Ra from 12 crushed rock and 12 soil samples from Nepal was measured in the laboratory using the radon accumulation method and Lucas scintillation flasks at three temperatures: 7, 22 and 37 • C. For each sample and at each temperature, 5 or 6 measurements were carried out, representing a total of 360 measurements, with an EC Ra average varying from 1.1 to 75 Bq kg −1 . While the effect is small, EC Ra was observed to increase with temperature in a significant and sufficiently reproducible manner. The increase was approximately linear with a slope (temperature sensitivity, TS) expressed in % • C −1 . We observed a large heterogeneity of TS with average values (range min-max) of 0.79 ± 0.05 (0.16-2.0) % • C −1 and 0.61 ± 0.05 (0.10-2.0) % • C −1 , for rock and soil samples, respectively. While this range overlaps with the results of previous studies, our values of TS tend to be smaller. The observed heterogeneity implies that the TS, rather poorly understood, needs to be assessed by dedicated experiments in every case where it is of consequence for the interpretation.
“…Overall, as a global average, at least 80 % of the radon emitted into the atmosphere comes from the uppermost ground layer [1]. The second most important contributor to environmental radon is emanation from groundwater sources [2, 3]. On the other hand, radon has many useful geophysical applications and has been applied as a natural tracer in various fields of hydrology, geochemistry and oceanography.…”
Section: Introductionmentioning
confidence: 99%
“…RAD7 detectors and synthetic water having varying amounts of NaCl and sea salt were used in their investigation. Lee et al [2, 3] have also reported the dependence of the radon k upon both temperature and groundwater impurities. They used LSC techniques and real groundwater samples in their work.…”
A simple method for the direct determination of the air-loop volume in a RAD7 system as well as the radon partition coefficient was developed allowing for an accurate measurement of the radon activity in any type of water. The air-loop volume may be measured directly using an external radon source and an empty bottle with a precisely measured volume. The partition coefficient and activity of radon in the water sample may then be determined via the RAD7 using the determined air-loop volume. Activity ratios instead of absolute activities were used to measure the air-loop volume and the radon partition coefficient. In order to verify this approach, we measured the radon partition coefficient in deionized water in the temperature range of 10–30 °C and compared the values to those calculated from the well-known Weigel equation. The results were within 5 % variance throughout the temperature range. We also applied the approach for measurement of the radon partition coefficient in synthetic saline water (0–75 ppt salinity) as well as tap water. The radon activity of the tap water sample was determined by this method as well as the standard RAD-H2O and BigBottle RAD-H2O. The results have shown good agreement between this method and the standard methods.
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