activities at any given station from the NERSN and other European countries like
Ukraine, Germany, Greece etc. The results obtained in different countries show a
remarkably similar time dependence for different distances from Chernobyl, soil
characteristics, climatological conditions etc. These results confirm that the atmospheric radionuclide resuspension processes are tightly coupled to the surrounding
ecosystems and to large timescale weather patterns (Viswanathan et al. 2000).
In further studies the initial experimental dataset for time series of deposition
was increased from 16 to 23 stations across Romania, for new analyses of the
deposition dynamics of
137 Cs, D(t). Using 23 selected stations and a longer period
of time (1987–1994), based this time on annually cumulated deposition samples, a
value which is closer to the previous one:
DðtÞ $ expðÀð0:0017 Æ 0:0007Þ tÞ
This value corresponds to 1.08 years effective half live.
The above was documented mainly for
137 Cs, but the same tendency was
observed also for
125
Sb and
106 Ru, based on annual cumulated deposition samples
from five NERSN station for the period 1987–1991.
The decline in
137
Cs activity concentrations in the environment is found to be
remarkably consistent over the period (1986–1992) by (Smith et al. 1999). They
linked diffusion of radiocesium into the illite lattice to changes in its long-term
environmental mobility and bioavailability. They found a long term exponential
decrease with a mean value k ¼ 0.00128 Æ 0.0005 day
À1 .
It is important to note that the study of the post Chernobyl deposition in Romania
is based on gamma spectrometric measurements performed at the same laboratory
(Environmental Radioactivity Laboratory Bucharest-Afumati) on the samples from
different sampling stations of the network (NERSN) having the same methodology
for sampling (IMH-CNA 1976; Suschny 1969). The samples were prepared daily at
the NERSN, measured beta global immediately and after 5 days, and cumulated
monthly for gamma spectrometric measurements. The ERL participated regularly
in annual intercomparison runs organised by IAEA Marine Environment Laboratory and IAEA Seibersdorf Laboratories between 1986 and 1993.
12.3.2 Deposition Velocities
Mean deposition velocities (cmÁs
À1 ) estimated from atmospheric aerosol and deposition measurements in Romania ( May 1986 at 21 stations from NERSN) and their
standard deviations, compared to data reported for Neuherberg from (Rosner et al.
1990) are presented in Table 12.1.
12 Pre and Post-Chernobyl Environmental Radioactivity in Romania: a Review
211
Ukraine, Germany, Greece etc. The results obtained in different countries show a
remarkably similar time dependence for different distances from Chernobyl, soil
characteristics, climatological conditions etc. These results confirm that the atmospheric radionuclide resuspension processes are tightly coupled to the surrounding
ecosystems and to large timescale weather patterns (Viswanathan et al. 2000).
In further studies the initial experimental dataset for time series of deposition
was increased from 16 to 23 stations across Romania, for new analyses of the
deposition dynamics of
137 Cs, D(t). Using 23 selected stations and a longer period
of time (1987–1994), based this time on annually cumulated deposition samples, a
value which is closer to the previous one:
DðtÞ $ expðÀð0:0017 Æ 0:0007Þ tÞ
This value corresponds to 1.08 years effective half live.
The above was documented mainly for
137 Cs, but the same tendency was
observed also for
125
Sb and
106 Ru, based on annual cumulated deposition samples
from five NERSN station for the period 1987–1991.
The decline in
137
Cs activity concentrations in the environment is found to be
remarkably consistent over the period (1986–1992) by (Smith et al. 1999). They
linked diffusion of radiocesium into the illite lattice to changes in its long-term
environmental mobility and bioavailability. They found a long term exponential
decrease with a mean value k ¼ 0.00128 Æ 0.0005 day
À1 .
It is important to note that the study of the post Chernobyl deposition in Romania
is based on gamma spectrometric measurements performed at the same laboratory
(Environmental Radioactivity Laboratory Bucharest-Afumati) on the samples from
different sampling stations of the network (NERSN) having the same methodology
for sampling (IMH-CNA 1976; Suschny 1969). The samples were prepared daily at
the NERSN, measured beta global immediately and after 5 days, and cumulated
monthly for gamma spectrometric measurements. The ERL participated regularly
in annual intercomparison runs organised by IAEA Marine Environment Laboratory and IAEA Seibersdorf Laboratories between 1986 and 1993.
12.3.2 Deposition Velocities
Mean deposition velocities (cmÁs
À1 ) estimated from atmospheric aerosol and deposition measurements in Romania ( May 1986 at 21 stations from NERSN) and their
standard deviations, compared to data reported for Neuherberg from (Rosner et al.
1990) are presented in Table 12.1.
12 Pre and Post-Chernobyl Environmental Radioactivity in Romania: a Review
211