Applicability of the closed-circuit accumulation chamber technique to measure radon surface exhalation rate under laboratory conditions

Intercomparison of Radon Flux Monitors at Low and at High Radium Content Areas under Field Conditions

“…Given that, a relationship is obtained with = 0.287 for 10% and = 0.625 for 20% maximum deviation. A similar theoretical study was completed [ 18 , 19 ] considering two points for the linear fit, but in this approach, pairs of values every 10 min from Figure 5 were used.…”

“…Other studies were experimentally based on the accumulation chamber method [ 15 , 16 ], resulting as a standard method reflected in the ISO 11665-7:2012 “Accumulation method for estimating surface exhalation rate” [ 17 ]. However, the quality and reliability of radon flux measurements is still challenging because of the influence that the monitor response, the installation of the accumulation chamber, the environmental parameters, and the soil properties could have on the measurements themselves, as reported by [ 18 , 19 ]. Research in this field is still ongoing, and many questions need to be answered.…”

Metrology for low-cost CO<sub>2</sub> sensors applications: the case of a steady-state through-flow (SS-TF) chamber for CO<sub>2</sub> fluxes observations

“…where V (m 3 ) and A (m 2 ) are the volume of the chamber and the enclosed soil surface area, respectively, CO 2_slope (ppm s −1 ) is the slope of the linear increment of the CO 2 concentration during the early accumulation time, P and T are the atmospheric pressure and the environmental temperature within the chamber, and R (m 3 Pa K −1 mol −1 ) is the universal gas constant. It has been pointed out that the linear approach of the accumulation method is only reliable for short time periods (Davidson et al, 2002;Grossi et al, 2012;Gutiérrez-Álvarez et al, 2020). Otherwise, the gradients of the environmental parameters between the inside and outside chamber could influence the measurement, probably yielding leakages of unknown origin in the chamber.…”

“…However, in the last decade, the improvement in the precision and the decrease in cost of non-dispersive infrared (NDIR) CO 2 sensors have made them more useful for multiple purposes (Yasuda et al, 2012). Their low weight and dimensions allow for their utilisation in a wide variety of applications, including unoccupied aerial vehicles (Kunz et al, 2018), CO 2 measurement network areas (Kim et al, 2018;Song et al, 2018), and for the study of the distribution of CO 2 in large regions, as in the case study of Switzerland (Müller et al, 2020). In order to be able to use these sensors in the outdoor atmosphere, a metrological effort is needed to (i) ensure a traceable and stable calibration, (ii) evaluate and correct the influence of the environmental parameters, such as temperature, relative humidity, and pressure, on the sensor response, and (iii) estimate the total uncertainty related with the sensor calibrations and corrections.…”

New application of low cost sensors for continuous CO<sub>2</sub> flux measurements

“…where 𝑉𝑉 (m 3 ) and 𝐴𝐴 (m 2 ) are the volume of the chamber and the enclosed soil surface area respectively, 𝐶𝐶𝐶𝐶 2_𝑠𝑠𝑠𝑠𝑃𝑃𝑠𝑠𝑠𝑠 (ppm•s -1 ) is the slope of the linear increment of the CO2 concentration during the early accumulation time, P and T are the atmospheric pressure and the environmental temperature within the chamber, and R (m 3 ⋅Pa⋅K −1 ⋅mol −1 ) is the universal gas constant. It has been underlined that the linear approach of the accumulation method is only reliable for short times (Davidson et al, 2002;Grossi et al, 2012;Gutiérrez-Álvarez et al, 2020). Otherwise, gradients of environmental parameters between the inside and outside chamber could influence the measurement, probably yielding to leakages of unknown origin in the chamber.…”