PSI - Issue 36

Volodymyr Sydorenko et al. / Procedia Structural Integrity 36 (2022) 318–325 Volodymyr Sydorenko, Sergiy Yeremenko, Viola Vambol et al. / Structural Integrity Procedia 00 (2021) 000 – 000

323

6

40

30

C 1 C 2

20

Y, m

10

0

10

20

30

40 50 60

X, m

Fig.3. Isopleths of the surface concentration of 137Cs in the air after a forest fire: C1> 25; С2 <25 - surface concentrations of 137Cs emitted into the atmosphere (Bq / m 3 ) The distribution of specific activity, for example, radiocaesium, in the structural fractions of soils (dust) after a forest fire depends on their genetic type. Without explaining the nature of this phenomenon within the framework of this work, it was the subject of special studies, we note that in peat and soddy-podzolic loamy soils, the specific activity of 137Сs s increases with a decrease in the diameter of structural fractions. In order to reveal the regularities in the distribution of 137Cs activity in the structural fractions of soils and to determine it in that part of the soil that is transported by the wind (we are talking about structural fractions up to 1 mm in diameter, aeolian material), special aerodynamic experimental studies were carried out, the results which are given in Table 2.

Table 2 Specific activity of radiocaesium in soils and their erosional fraction Statistical indicator Sod-podzolic loamy

Sod-podzolic loamy

Peat

ground

aeolian material

ground

aeolian material

ground

aeolian material

Specific activity, 137Cs, Bq / kg

770

550

760

780

540

990

Standard error, Bq / kg

214,7

219,3

150,4

143,2

115,8

175,1

Standard deviation

607,2

620,4

425,5

405,1

463,0

700,2

Sample variance

368691

384882

181053

164100

214375

490327

Excess

4,68

6,84

0,84

0,21

3,98

0,74

Minimum

200

70

270

250

113

187

Maximum

2150

2045

1575

1505

1810

2470

Coefficient of variation

79,0

113,0

56,3

51,8

86,3

71,1

From the data given in Table 2, we see that the activity of 137Cs in the aeolian material of the three types of soils, analyzed, ranged from 540 on mineral soils to 990 Bq / kg on organogenic soils. Moreover, the activity of the aeolian material of peat bogs was 1.8 times higher than the specific activity of the aeolian material (0-5) cm in the soil layer. The coefficient of intensity of 137Cs deflation after a forest fire was determined according to the data of field observations: