12.2.2 Natural Radioactivity Studies
The study of the daily variation of radon and thoron daughters in the free atmosphere in connection with meteorological parameters was initiated at ERL in 1977
in order to better understand daily and seasonal variation of natural radioactivity
and to improve the response of the network in emergency situations based on gross
beta measurements of aerosol filters.
New methodology and formulas for the interpretation and calculation of
Radon (
222
Rn), Thoron (
220 Rn) and residual (anthropogenic) activities from
gross beta measurements of aerosol samples were introduced in daily measurements at the NERSN stations (Sima 1978; Sima et al. 1986).
This methodology, slightly modified, was used for the studies on Radon and
Thoron daughters in moffets (Sonoc et al. 1984b) and for the estimation of the
diffusion coefficient (K z ) in the atmospheric boundary layer (Dovlete et al. 1986).
More complex meteorological and aerosol radioactivity experiments performed
in situ on the meteorological platform at ERL, enabled us to confirm that stability
class, temperature gradient in the boundary layer and soil moisture were the
important parameters influencing the level of natural radioactivity in the lower
atmosphere (boundary layer). The influence of snow cover on the concentrations of
Radon and Thoron daughters in the atmosphere was the object of the study
presented in (Sima et al. 1983).
The methodology based on air filtration for the determination of the gamma
emitting daughters of
222 Rn and
220 Rn from the atmosphere were published and
used for
214 Pb,
214 Bi,
212
Pb,
212 Bi measurements at ERL (Dovlete 1983). The
method for the determination of natural radioactivity on aerosol filters based on
alpha spectrometric measurements was presented in (Sonoc and Sima 1992).
12.2.3 Danube Radioactivity
The ERL participated in the Danube International Expedition from Tulcea to
Bratislava (24 august–4 October 1978) (Ghedeonov 1983) to study the radioactivity
along the river. Water, sediment, aquatic vegetation and fish samples were measured on board of the research vessel using high resolution GeLi detectors and
Compton suppression spectrometers. The
137 Cs specific activity in Danube water
was less than 5 Bq/m
3 .
The radioactivity monitoring programme for Danube and Danube delta were
continued in the period 1979–1984. Sediment samples from Danube (Drobeta Tr
Severin and Sulina) and Razelm Lake for the period 1979–1981 were analysed and
the results presented in (Dovlete et al. 1983b; Sonoc et al. 1984a).
Natural radionuclides like
40 K, radionuclides from natural radioactive series of
U-Ra and Th were identified in sediment samples, together with
137 Cs.
206
C. Dovlete et al.
The study of the daily variation of radon and thoron daughters in the free atmosphere in connection with meteorological parameters was initiated at ERL in 1977
in order to better understand daily and seasonal variation of natural radioactivity
and to improve the response of the network in emergency situations based on gross
beta measurements of aerosol filters.
New methodology and formulas for the interpretation and calculation of
Radon (
222
Rn), Thoron (
220 Rn) and residual (anthropogenic) activities from
gross beta measurements of aerosol samples were introduced in daily measurements at the NERSN stations (Sima 1978; Sima et al. 1986).
This methodology, slightly modified, was used for the studies on Radon and
Thoron daughters in moffets (Sonoc et al. 1984b) and for the estimation of the
diffusion coefficient (K z ) in the atmospheric boundary layer (Dovlete et al. 1986).
More complex meteorological and aerosol radioactivity experiments performed
in situ on the meteorological platform at ERL, enabled us to confirm that stability
class, temperature gradient in the boundary layer and soil moisture were the
important parameters influencing the level of natural radioactivity in the lower
atmosphere (boundary layer). The influence of snow cover on the concentrations of
Radon and Thoron daughters in the atmosphere was the object of the study
presented in (Sima et al. 1983).
The methodology based on air filtration for the determination of the gamma
emitting daughters of
222 Rn and
220 Rn from the atmosphere were published and
used for
214 Pb,
214 Bi,
212
Pb,
212 Bi measurements at ERL (Dovlete 1983). The
method for the determination of natural radioactivity on aerosol filters based on
alpha spectrometric measurements was presented in (Sonoc and Sima 1992).
12.2.3 Danube Radioactivity
The ERL participated in the Danube International Expedition from Tulcea to
Bratislava (24 august–4 October 1978) (Ghedeonov 1983) to study the radioactivity
along the river. Water, sediment, aquatic vegetation and fish samples were measured on board of the research vessel using high resolution GeLi detectors and
Compton suppression spectrometers. The
137 Cs specific activity in Danube water
was less than 5 Bq/m
3 .
The radioactivity monitoring programme for Danube and Danube delta were
continued in the period 1979–1984. Sediment samples from Danube (Drobeta Tr
Severin and Sulina) and Razelm Lake for the period 1979–1981 were analysed and
the results presented in (Dovlete et al. 1983b; Sonoc et al. 1984a).
Natural radionuclides like
40 K, radionuclides from natural radioactive series of
U-Ra and Th were identified in sediment samples, together with
137 Cs.
206
C. Dovlete et al.