13.3 Results
Each sample was evaluated for its radionuclide concentrations and in some cases,
like the off-shore water samples from Constanta Est 6 and 7, the measurements
were under the minimum detectable activity (MDA) and no radionuclide was
clearly identified above the background radiation. Water samples provide specific
issues regarded to the gamma scattering and attenuations within the sample and the
actual efficiency and calibration correction coefficients needed to be adjusted for
the actual experimental setup using LabSOCS detector simulation. While other
codes like GESPECOR (Sima and Arnold 2002) provide a consistent overview, we
employed LabSOCS as the spectrometer supplier main method for parameter
correction (Done et al. 2015) (Table 13.1).
Soil samples, mainly sediments, raised specific issues related to the homogeneity
due the fact that each area has specific soil compositions. In order to provide
accurate results, each sample has to be corrected to its specific density, weight
and size – meaning for each sample, different detector coefficient corrections
needed to be applied. The presence of wood and other materials was avoided due
the fact that they have high concentrations of
40 K (Table 13.2).
Table 13.1 Seawater sample radionuclide evaluation
#
Sample
Radionuclide
Activity [Bq/l]
MDA [Bq/l]
1
Constanta EST 2
40
K
5.10 Æ 0.6
0.90
2
214
Bi
2.59 Æ 0.34
0.17
3
214
Pb
2.45 Æ 0.36
0.20
4
241
Am
0.13 Æ 0.07
0.12
5
Constanta EST 3
40
K
4.40 Æ 0.51
0.90
6
214
Bi
0.52 Æ 0.07
0.18
7
214
Pb
0.56 Æ 0.08
0.18
9
Constanta EST 4
40
K
3.10 Æ 0.36
0.98
10
Constanta EST 5
40
K
4.7 Æ 0.55
0.98
11
214
Bi
1.28 Æ 0.17
0.18
12
214
Pb
1.06 Æ 0.16
0.18
13
Sf. Gheorghe 2
40
K
8.30 Æ 0.95
0.68
14
214
Bi
0.25 Æ 0.03
0.13
15
214
Pb
0.24 Æ 0.04
0.14
16
Sf. Gheorghe 3
40
K
17.20 Æ 1.98
0.84
17
214
Bi
2.02 Æ 0.26
0.18
18
214
Pb
2.06 Æ 1.26
0.20
19
Sf. Gheorghe 3
40
K
4.90 Æ 0.57
0.87
20
214
Bi
1.55 Æ 0.20
0.17
21
214
Pb
1.26 Æ 0.39
0.20
Only the valid data (determinations greater the MDA Minimum Detectable Activity – were
presented
13 Radionuclides Assessment for the Romanian Black Sea Shelf
225
Each sample was evaluated for its radionuclide concentrations and in some cases,
like the off-shore water samples from Constanta Est 6 and 7, the measurements
were under the minimum detectable activity (MDA) and no radionuclide was
clearly identified above the background radiation. Water samples provide specific
issues regarded to the gamma scattering and attenuations within the sample and the
actual efficiency and calibration correction coefficients needed to be adjusted for
the actual experimental setup using LabSOCS detector simulation. While other
codes like GESPECOR (Sima and Arnold 2002) provide a consistent overview, we
employed LabSOCS as the spectrometer supplier main method for parameter
correction (Done et al. 2015) (Table 13.1).
Soil samples, mainly sediments, raised specific issues related to the homogeneity
due the fact that each area has specific soil compositions. In order to provide
accurate results, each sample has to be corrected to its specific density, weight
and size – meaning for each sample, different detector coefficient corrections
needed to be applied. The presence of wood and other materials was avoided due
the fact that they have high concentrations of
40 K (Table 13.2).
Table 13.1 Seawater sample radionuclide evaluation
#
Sample
Radionuclide
Activity [Bq/l]
MDA [Bq/l]
1
Constanta EST 2
40
K
5.10 Æ 0.6
0.90
2
214
Bi
2.59 Æ 0.34
0.17
3
214
Pb
2.45 Æ 0.36
0.20
4
241
Am
0.13 Æ 0.07
0.12
5
Constanta EST 3
40
K
4.40 Æ 0.51
0.90
6
214
Bi
0.52 Æ 0.07
0.18
7
214
Pb
0.56 Æ 0.08
0.18
9
Constanta EST 4
40
K
3.10 Æ 0.36
0.98
10
Constanta EST 5
40
K
4.7 Æ 0.55
0.98
11
214
Bi
1.28 Æ 0.17
0.18
12
214
Pb
1.06 Æ 0.16
0.18
13
Sf. Gheorghe 2
40
K
8.30 Æ 0.95
0.68
14
214
Bi
0.25 Æ 0.03
0.13
15
214
Pb
0.24 Æ 0.04
0.14
16
Sf. Gheorghe 3
40
K
17.20 Æ 1.98
0.84
17
214
Bi
2.02 Æ 0.26
0.18
18
214
Pb
2.06 Æ 1.26
0.20
19
Sf. Gheorghe 3
40
K
4.90 Æ 0.57
0.87
20
214
Bi
1.55 Æ 0.20
0.17
21
214
Pb
1.26 Æ 0.39
0.20
Only the valid data (determinations greater the MDA Minimum Detectable Activity – were
presented
13 Radionuclides Assessment for the Romanian Black Sea Shelf
225