122
plants reached a constant value and did not increase at a concentration of
1000 mg kg
−1
(Zimakov and Lazarev 1984). Malikov et al. (1988b) studied on
leached chernozem and noticed an increase in the concentration of
238
U in the soil
from 100 to 500 mg kg
−1
caused an increase in AC of
238
U for alfalfa, Sudan grass
and roots of red and sugar beet by a factor of 1.8–4.7 and had practically no effect
on the accumulation of uranium by peas, cucumbers and tomatoes.
The data of the greenhouse experiment with spring barley on sod-podzolic
medium loamy soil contaminated with UO 2 (NO 3 ) 2 × 6H 2 O showed that at a
238
U
concentration of 150 mg kg
−1
of soil, there was a detectable inhibition of barley
plants, which appeared in a 1.2-fold decrease in growth in comparison with the
control. The decrease in the biomass of barley straw at a concentration of
238
U of
100–150 mg kg
−1
of soil was 1.5–2.0 times, and the mass of grain decreased by a
factor of 1.2. The levels of radionuclide content in barley straw were 2.5–8.0 times
higher than in grain. Application of the modified diatomite-based sorbent in an
amount of 0.5 g kg
−1
to the soil containing 100 mg kg
−1
of
238
U reduced the accumulation of radionuclide by barley straw in average by 10% (Kuliyeva and Kasyanenko
2009).
The process of intake of
238
U in plants occurs continuously throughout the entire
vegetation period, and plants accumulate the radionuclide per unit mass in the earlier phases of their development more than in later phases (Ratnikov et al. 2007).
The largest amount of
238
U in plants accumulates in the earing phase of oats and
barley (Ratnikov et al. 2007) (Table 4).
Over the time, the physical and chemical state and strength of
238
U fixation in
radioactively contaminated soils may change. Thus, in model-field experiments, it
was found that the biological absorption of a radionuclide depends on its initial
Table 4 The concentration of
238 U in oat and barley plants during the vegetation period, Bq kg
−1
dry weight
Types of soils
Oats
Barley
20-day
plants
Vegetative mass after
45 days
20-day
plants
Vegetative mass after
45 days
Sod-podzolic sandy
loam
(Vladimir region)
6.0
13.2
4.7
10.2
Sod-podzolic sandy
loam
(Moscow region)
9.8
22.7
6.5
15.1
Sod-podzolic medium
loamy
(Kaluga region)
6.9
10.8
5.2
8.4
Grey forest medium
loamy
(Kaluga region)
5.3
9.2
4.2
7.0
Leached chernozem
(Tula region)
4.5
7.1
3.1
5.9
Greenhouse experiment (Adopted from Kuliyeva and Kasyanenko 2009)
A. N. Ratnikov et al.
plants reached a constant value and did not increase at a concentration of
1000 mg kg
−1
(Zimakov and Lazarev 1984). Malikov et al. (1988b) studied on
leached chernozem and noticed an increase in the concentration of
238
U in the soil
from 100 to 500 mg kg
−1
caused an increase in AC of
238
U for alfalfa, Sudan grass
and roots of red and sugar beet by a factor of 1.8–4.7 and had practically no effect
on the accumulation of uranium by peas, cucumbers and tomatoes.
The data of the greenhouse experiment with spring barley on sod-podzolic
medium loamy soil contaminated with UO 2 (NO 3 ) 2 × 6H 2 O showed that at a
238
U
concentration of 150 mg kg
−1
of soil, there was a detectable inhibition of barley
plants, which appeared in a 1.2-fold decrease in growth in comparison with the
control. The decrease in the biomass of barley straw at a concentration of
238
U of
100–150 mg kg
−1
of soil was 1.5–2.0 times, and the mass of grain decreased by a
factor of 1.2. The levels of radionuclide content in barley straw were 2.5–8.0 times
higher than in grain. Application of the modified diatomite-based sorbent in an
amount of 0.5 g kg
−1
to the soil containing 100 mg kg
−1
of
238
U reduced the accumulation of radionuclide by barley straw in average by 10% (Kuliyeva and Kasyanenko
2009).
The process of intake of
238
U in plants occurs continuously throughout the entire
vegetation period, and plants accumulate the radionuclide per unit mass in the earlier phases of their development more than in later phases (Ratnikov et al. 2007).
The largest amount of
238
U in plants accumulates in the earing phase of oats and
barley (Ratnikov et al. 2007) (Table 4).
Over the time, the physical and chemical state and strength of
238
U fixation in
radioactively contaminated soils may change. Thus, in model-field experiments, it
was found that the biological absorption of a radionuclide depends on its initial
Table 4 The concentration of
238 U in oat and barley plants during the vegetation period, Bq kg
−1
dry weight
Types of soils
Oats
Barley
20-day
plants
Vegetative mass after
45 days
20-day
plants
Vegetative mass after
45 days
Sod-podzolic sandy
loam
(Vladimir region)
6.0
13.2
4.7
10.2
Sod-podzolic sandy
loam
(Moscow region)
9.8
22.7
6.5
15.1
Sod-podzolic medium
loamy
(Kaluga region)
6.9
10.8
5.2
8.4
Grey forest medium
loamy
(Kaluga region)
5.3
9.2
4.2
7.0
Leached chernozem
(Tula region)
4.5
7.1
3.1
5.9
Greenhouse experiment (Adopted from Kuliyeva and Kasyanenko 2009)
A. N. Ratnikov et al.