118
1.1–7.5%, by 1N ammonium acetate solution is 2.4–40.8% and by 2N HNO 3 solution is 51.3–79.2% (Alexakhin et al. 1985) (Table 1).
The studies of Arkhipov et al. (1986) established the limits of the absolute and
relative content of gross, acid-soluble and exchangeable forms of natural radionuclides (
238
U,
232
Th,
226
Ra,
210
Po and
210
Pb) in the different types of soils of the Russian
Federation. The gross content of
238
U is 7.4–18.5 Bq kg
−1
in sod-podzolic soils,
22.2–37.0 Bq kg
−1
in chernozems, 25.9 Bq kg
−1
in kastanozems, 29.6 Bq kg
−1
in
brown semi-desert soils and 25.9 Bq kg
−1
in sierozems. The content of the acidsoluble forms of
238
U is 6–26% of the gross content, depending on the agrochemical
properties of the soil. The amount of exchangeable and water-soluble forms of
238
U
in sod-podzolic soils varies between 18% and 40%, in chernozem 9–12% of gross
soil content (Arkhipov et al. 1986).
By this means, a generalisation of the accumulated data indicates that intensive
and strong absorption of
238
U in soils occurs mainly due to organic matter and clay
minerals. The processes of ion exchange, complexation, hydrolysis and oxidationreduction designate the fixation of
238
U in soils.
To date, there is a lack of the investigation of the temporal aspects of
238
U absorption processes in various soils. The existing research methodologies do not allow to
fully evaluate the transformation of forms and mechanisms of radionuclide binding
in soils. One of the ways to overcome these difficulties can be carrying out complex
238
U full-scale and model studies (Arkhipov and Fedorova 1981).
Table 1 Rate and strength of sorption of
238 UO 2 (NO 3 ) 2 in different types of soils (in relation to the
original quantity), % (adopted from Alexakhin et al. 1985)
Soil type
Sorption
Desorption
H 2 O
1N CH 3 COONH 4
2N HNO 3
Sod-podzolic
97.0
1.7
2.4
54.6
Dark-grey forest
98.4
1.2
11.7
59.5
Grey forest
96.9
1.4
3.2
51.3
Brown forest
88.4
1.2
36.2
79.2
Chernozem
Leached
98.5
1.2
13.4
68.4
Podzolic
82.2
5.9
24.1
51.3
Usual
85.9
7.5
9.6
57.0
Southern
90.9
3.6
25.6
68.4
Firm
98.1
1.1
22.2
76.4
Meadow chernozem
89.1
5.6
22.3
69.5
Sod
82.2
5.9
24.1
51.3
Meadow
99.2
1.5
23.6
60.8
Humic-gleyed
98.1
1.1
14.8
72.8
Meadow-swampy
87.5
3.6
23.0
69.2
Dark kastanozem
93.6
3.8
32.8
77.2
Kastanozem
87.0
4.8
40.8
61.2
Light kastanozem
87.4
4.4
26.4
72.0
A. N. Ratnikov et al.
1.1–7.5%, by 1N ammonium acetate solution is 2.4–40.8% and by 2N HNO 3 solution is 51.3–79.2% (Alexakhin et al. 1985) (Table 1).
The studies of Arkhipov et al. (1986) established the limits of the absolute and
relative content of gross, acid-soluble and exchangeable forms of natural radionuclides (
238
U,
232
Th,
226
Ra,
210
Po and
210
Pb) in the different types of soils of the Russian
Federation. The gross content of
238
U is 7.4–18.5 Bq kg
−1
in sod-podzolic soils,
22.2–37.0 Bq kg
−1
in chernozems, 25.9 Bq kg
−1
in kastanozems, 29.6 Bq kg
−1
in
brown semi-desert soils and 25.9 Bq kg
−1
in sierozems. The content of the acidsoluble forms of
238
U is 6–26% of the gross content, depending on the agrochemical
properties of the soil. The amount of exchangeable and water-soluble forms of
238
U
in sod-podzolic soils varies between 18% and 40%, in chernozem 9–12% of gross
soil content (Arkhipov et al. 1986).
By this means, a generalisation of the accumulated data indicates that intensive
and strong absorption of
238
U in soils occurs mainly due to organic matter and clay
minerals. The processes of ion exchange, complexation, hydrolysis and oxidationreduction designate the fixation of
238
U in soils.
To date, there is a lack of the investigation of the temporal aspects of
238
U absorption processes in various soils. The existing research methodologies do not allow to
fully evaluate the transformation of forms and mechanisms of radionuclide binding
in soils. One of the ways to overcome these difficulties can be carrying out complex
238
U full-scale and model studies (Arkhipov and Fedorova 1981).
Table 1 Rate and strength of sorption of
238 UO 2 (NO 3 ) 2 in different types of soils (in relation to the
original quantity), % (adopted from Alexakhin et al. 1985)
Soil type
Sorption
Desorption
H 2 O
1N CH 3 COONH 4
2N HNO 3
Sod-podzolic
97.0
1.7
2.4
54.6
Dark-grey forest
98.4
1.2
11.7
59.5
Grey forest
96.9
1.4
3.2
51.3
Brown forest
88.4
1.2
36.2
79.2
Chernozem
Leached
98.5
1.2
13.4
68.4
Podzolic
82.2
5.9
24.1
51.3
Usual
85.9
7.5
9.6
57.0
Southern
90.9
3.6
25.6
68.4
Firm
98.1
1.1
22.2
76.4
Meadow chernozem
89.1
5.6
22.3
69.5
Sod
82.2
5.9
24.1
51.3
Meadow
99.2
1.5
23.6
60.8
Humic-gleyed
98.1
1.1
14.8
72.8
Meadow-swampy
87.5
3.6
23.0
69.2
Dark kastanozem
93.6
3.8
32.8
77.2
Kastanozem
87.0
4.8
40.8
61.2
Light kastanozem
87.4
4.4
26.4
72.0
A. N. Ratnikov et al.