ats INTERNATIONAL SYMPOSIUM ON TRACE GASES AND RADIOACTIVITY 3809 1 librium with Rn™ will be smaller d level but will extend to greater pepeven -ratio eet Sort a > Table 1). imental proof of the disturbance in ty layer of the radioactive equiliben Rn™ and Pb™or Bi™is possible 1eous measurements of Rn™ with the r of the scintillation chamber method 4 and Bi™ by the filter method. A aneous measurements of this kind, rather undefined terrain, were made 't al. [1959]. The average Bi™‘/Rn™ measurements at a height of 1 to 10 st of them during daytime—was 0.4 ioactive equilibrium was found only er strong inversions at night and in g. Minimum values of about 0.2 to served in the noon and afternoon. proof of the theoretical results resurements of the Rn™ and Pb™ les in the boundary layer during pether constant atmospheric stability. ‘oretical results demonstrate the posbtaining valuable information on the } im © 2 ° j 3 es 0,1 Le eT £ 0,05 2 a a a —- 5 0 | 3 Altitude 10 1Skm Vertical variation of the Pb™/Rn and Po”*/Pb”® ratios for different values of the removal half-life 7 (calculated with K profile NNN). mixing rate in the boundary layer from mea- surements of the ratios of Rn™ and its decay products. Pband Po’. The vertical distribution of Pb”? (ti. = 19.4 years) and Po” (t,. = 138 an =z 1 Rn atom/em?’sec and with fe of removal). —— 40 0.0! km 30km 10km 20km LT a, Tkm km 0,2 o~ Fig. 8. 100 rm | ON E 10m 05 days) is limited by the washout and rainout of these nuclides in the troposphere. Their removal was taken into account by ineluding the term with the removal rate A in (1) and (2). The corresponding half-life of elimination is T = (In 2)/A. The assumption of a constant value of A is but a rough approximation, valid only for average conditions and time periods which are long compared with the duration of single precipitation processes. Because of the nature of this assumption, calculations of the equilibrium Pb” and Po” profiles were not justified for extreme turbulence conditions; therefore, the computations were restricted to the mean K profile NNN given in Figure 1.