Diurnal variations of ²¹⁸Po, ²¹⁴Pb, and ²¹⁴Po and their effect on atmospheric electrical conductivity in the lower atmosphere at Mysore

The short-lived radon daughters (²¹⁸Po, ²¹⁴Pb, ²¹⁴Bi and ²¹⁴Po) are natural tracers in the troposphere in particular near the ground surface. They are electrically charged particles and are chemically reactive. As soon as they are formed they get attached to the aerosol particles of the atmosphere. Their behaviour is similar to that of aerosols with respect to their growth, transport, removal processes in the atmosphere. The electrical conductivity of the atmosphere is mainly due to the presence of highly mobile (small) ions. Hence the electrical conductivity of air at near the surface of the earth mainly due to ²²²Rn, ²¹⁸Po, ²¹⁴Pb, ²¹⁴Bi and ²¹⁴Po concentrations, and depends on aerosol concentrations and meteorological parameters. The individual radon progeny concentrations (²¹⁸Po, ²¹⁴Pb, and ²¹⁴Po) are measured using Air Flow meter. The concentration of radon in the atmospheric air is measured using Low Level Radon Detection System. The total energy released due to both radon and its progeny is computed in energy units (eV cm^-3s^-1) and is converted into ion-pair production rate (No. cm^-3 s^-1), 32 eV being the energy producing one-ion pair. The atmospheric electrical conductivity (both positive and negative) is measured using a Gerdien's apparatus with two identical tubes. The average values of ²¹⁸Po, ²¹⁴Pb, and ²¹⁴Po are respectively 13.70, 1.45 and 1.92 Bq m^-3 respectively. The average value of positive and negative electrical conductivity are 5.08 x 10^-14U^-1 m^-1 and 4.67 x 10^-14 U^-1 m^-1. The concentrations of radon, its progeny, and positive and negative conductivity show a similar kind of diurnal variations with maximum in the early morning hours and a minimum during day time. The activity is higher in winter than in summer and rainy season. (author)