31
Type of Biota
71
Kattegat
75
Belt Sea
81
Baltic Sea
West
83
Baltic Sea
East
85
Bothnian
Sea
87
Bothnian
Bay
89
Gulf of
Finland
91
Gulf of
Riga
137 Cs:
Marine fish:
round fish, flesh
35 ±8
125 ±36
164 ± 18
164 ± 20
188 ±26
261 ± 28
194 ±67
round fish, edible parts
153 ± 32
154 ± 18
230 ± 29
206 ± 28
211 ±8
flat fish, flesh
63 ±33
215 ± 6
129 ± 15
160 ±48
Freshwater fish:
Pike, flesh
Esox lucius
310 ±50
564 ± 220
555 ±111
602±142
Perch, flesh
Perea fluviatilis
285 ± 76
Aquatic Plants:
Brown algae,
Fucus vesiculosus
188 ± 39
215 ±26
453±145
522 ± 73
622 ±100
1247 ±424
390±156
“Sr:
Marine fish:
round fish, flesh
0.23 ± 0.06
0.39 ±0.13
0.34 ±0.15
round fish, edible
parts
3.0 ±0.5
3.1 ± 0.7
6.4 ±1.6
2.7 ±0.5
4.2
(1 value)
flat fish, flesh
1.1 ±1.2
1.2 ± 1.1
3.4 ±2.4
Freshwater fish:
Pike, flesh
Esox lucius
1.7 ± 0.5
1.5 ±0.4
4.0 ±1.5
Perch, flesh
Perea fluviatilis
3.1 ±1.4
Aquatic Plants:
Brown algae,
Fucus vesiculosus
206±165
162 ± 94
821 ±174
858 ± 96
664±163
Table 1:
,37 Cs and “Sr concentration
factors and standard
uncertainties of fish (in I kg 1
wet) and Fucus vesiculosus (in
I kg 1 dry) estimated in different
model-related Baltic Sea areas
for the years 1988/1990 - 2006.
Marine fish have been grouped
as follows:
Round fish : herring, cod and
whiting; Flat fish : flounder,
plaice and dab.
freshwater contributions to the Baltic
seawater, the marine biota concentration
factors (CF) as recommended by the
International Atomic Energy Agency IAEA
(1985 and 2004) cannot be used. As the
earlier determinations of concentration factors
(HELCOM 1995) suffered partly from non
equilibrium states of the Chernobyl-derived
Cs in biota, new estimates of the CFs were
obtained from biota and seawater data from
the years up to 2006, starting from 1990
( 137 Cs) and 1988 ( 90 Sr). For each year, nuclide
and water box, a CF value was calculated
using the ratio between the annual means of
the biota specific activity and surface seawater
activity concentrations. The various time
series of CF values were treated statistically
including robust methods ensuring reduced
influence from outliers. Table 1 shows the
results of estimated concentration factors of
fish and Fucus vesiculosus.
It is clear that for marine fish species the
137 Cs CF values increase from western Baltic
Sea areas to eastern/northern areas, which
is explained by the corresponding increase
of freshwater contributions to the seawater.
The values from Table 1 have been used
for comparing the modelled and measured
137 Cs and 90 Sractivities offish and Fucus
vesiculosus, respectively. See Chapter 4
(modelling/dose) for these results.
3C.4.2 Activity concentrations
The following tables show extreme values of
activity concentrations for the representative
beta/gamma-emitting radionuclides, 137 Cs
and 90 Sr, and the alpha emitters, 239 24 °Pu
and 241 Am, as observed during the period
1999-2006.
The values obtained for the dominant
fish species are shown in Table 2. One
outstanding 137 Cs value of 41 Bq kg 1 wet
weight was observed for cod; it belonged to
a single large specimen (collected in 2000,
Southern Baltic Proper); the next highest
value was 23 Bq kg 1 wet weight. The latter
value then represents the maximum value for
the marine fish species. Among the freshwater
fish, represented by pike and perch, pike
showed even larger 137 Cs values due to their
higher concentration factors. While perch
were collected in the Gulf of Riga, pike were
collected in waters adjacent to the Finnish
coast. The larger 137 Cs values for pike were
observed near the coast of the Bothnian Sea.
For "Sr, a radionuclide mainly derived from
nuclear weapons testing fallout and related
runoff from rivers, values for specific activity
are more than two orders of magnitude lower
than those of 137 Cs. The "Sr activities in the
flesh of flat fish species (flounder, plaice)
exhibit slightly larger values than in round fish
Baltic Sea Environment Proceedings No. 117
