Diurnal and seasonal variation of short-lived radon progeny concentration and atmospheric temporal variations of 210Pb and 7Be in Egypt

Radon and thoron progeny concentration variability in relation to meteorological conditions at Bucharest (Romania)

“…The lowest radon progeny concentrations are recorded during the springesummer months when atmospheric turbulence is high and soil humidity is also high. The data presented in this paper are in good agreement with literature data (Moses et al, 1963;Duen˜as et al, 1994;Eisenbud and Gesell, 1997;Winkler and Aehlig, 1998;El-Hussein et al, 2001;Winkler et al, 2001;Sesana et al, 2003). The lowest thoron progeny concentrations were recorded in the winter months characterised by significant snow coverage of the soil for many days.…”

“…The significant inverse correlations between radon/thoron progeny in air and wind speed during the aspiration interval are in good agreement with references in the literature (Moses et al, 1963;Ikebe, 1970;Porstendo¨rfer et al, 1994;Duen˜as et al, 1996a;Duen˜as et al, 1996b;El-Hussein et al, 2001;Winkler et al, 2001) and are mainly related to turbulent diffusion processes in the atmosphere. During strong winds, diffusion rates are high and therefore lower concentrations of radon, thoron and their progeny are observed near the ground.…”

“…Thoron progeny concentrations, Bq m A p r -9 4 J u l-9 4 O c t-9 4 J a n -9 5 A p r -9 5 J u l-9 5 O c t-9 5 J a n -9 6 A p r -9 6 J u l-9 6 O c t-9 6 J a n -9 7 A p r -9 7 J u l-9 7 O c t-9 7 J a n -9 8 A p r -9 8 J u l-9 8 O c t-9 8 J a n -9 9 A p r -9 9 A p r -9 4 J u n -9 4 A u g -9 4 O c t-9 4 D e c -9 4 F e b -9 5 A p r -9 5 J u n -9 5 A u g -9 5 O c t-9 5 D e c -9 5 F e b -9 6 A p r -9 6 J u n -9 6 A u g -9 6 O c t-9 6 D e c -9 6 F e b -9 7 A p r -9 7 J u n -9 7 A u g -9 7 O c t-9 7 D e c -9 7 F e b -9 8 A p r -9 8 J u n -9 8 A u g -9 8 O c t-9 8 D e c -9 8 F e b -9 9 A p r -9 9 The daily variations of radon and thoron progeny activity concentrations in the atmosphere for the analysed period follow the daily variations of the boundary layer and are similar to other daily variations in radon/thoron and their progeny levels reported in the literature (Moses et al, 1963;Fujinami and Esaka, 1988;Allegrini et al, 1994;Butterweck et al, 1994;Porstendo¨rfer, 1994;El-Hussein et al, 2001;Winkler et al, 2001;Magalhaes et al, 2003;Sesana et al, 2003). While the relative short-term variations of the exhalation rate are generally small (Porstendo¨rfer, 1994;Beck and Gogolak, 1979), experimental studies (Ikebe, 1970;Fujinami and Esaka, 1988;Porstendo¨rfer et al, 1994;Butterweck et al, 1994;Allegrini et al, 1994;Sesana et al, 2003) show that the daily fluctuations of radioactivity levels in the atmosphere are principally due to the relative short-term changes in the vertical diffusivity in the boundary layer.…”

Seasonal variations of aerosol residence time in the lower atmospheric boundary layer

“…As the attachment rates of 214 Pb radionuclides to aerosol particles and meteorological variables within the whole year were different, the activity concentrations varied between 0.2 and 3.87 Bq m À3 with an average value of 1:4 AE 0:27 Bq m À3 . This mean value was found to be lower than our previous mean value (4:9 AE 0:5 Bq m À3 ) which was obtained in the same location but at a height of 2 m above the ground level (El-Hussein et al, 2001). This deviation can be related to some factors: (1) the 222 Rn gas concentration decreases with height above the ground level, (2) the emanation rate of 222 Rn from the soil is influenced by the meteorological conditions where decreasing temperature and WS decreases the emanation rate, and (3) the activity concentration of short-lived radon progeny is influenced by their transport in the atmosphere, turbulent mixing conditions and by the radioactive decay (Jacobi and André, 1963).…”

“…As the relative rates of coagulation, deposition and other removal processes of 210 Pb from the atmosphere over the four seasons were different, the activity concentrations varied between 0.166 and 4.49 mBq m À3 with an average value of 1:2 AE 0:15 mBq m À3 . This mean value is found to be higher than our previous mean value of 0.37 mBq m À3 (El-Hussein et al, 2001). However, this can be related to the MRT of attached aerosol particles with long-lived radionuclides (half-life > 1 d) in the atmosphere.…”