Simultaneous measurements of radon (Rn222) and thoron (Rn220) in the atmospheric surface layer

Abstract
Simultaneous, direct measurements of the radon and thoron contents in the air near the ground have been made, using apparatus adapted from those of Norinder et al. (1952) and Israel (1964). Data of the diurnal variations and the vertical distributions of radon and thoron are presented. According to measurements the vertical gradients of radon and thoron are greatest near the ground surface at night. The ratios between the concentrations of thoron and radon vary on an average from 0.1 to about 3.0 in the layer up to the height 3 m above the ground surface. Fourier analyses are made of variations with time of radon and thoron concentrations. For radon a few harmonics represent the diurnal wave. For thoron, however, several harmonics are needed. DOI: 10.1111/j.2153-3490.1973.tb00612.x