ABSTRACT
Losses of Rn during transportation and storage may occur, if sampling vessels are permeable to gas, or if they have leaky stopcocks and caps. Analytical methods that have been used in other laboratories for the determination of Rn are briefly described hereafter, followed by detailed descriptions of the methods used in this study at the US Geological Survey's laboratory in Denver, Colo. In the direct liquid-scintillation counting method, a 10-mL water sample is mixed with 5 mL of toluene-based liquid-scintillation fluid, followed by measurement of radioactivity in a liquid-scintillation counter. In the extraction concentration and liquid-scintillation counting method, a large-volume water sample, about 500 mL, is extracted with 20 mL of toluene in a closed system, and toluene is separated from the water for liquid-scintillation counting. Label and transport samples to the laboratory in the same manner described for the surface-water samples.
