It is evident that the mean values are close to each other and if they are
combined, the total mean for all brown and green algae is the following:
10 + 1 Bq/kg (N ¼ 40, range 2–25 Bq/kg) for brown species and 8.6 + 0.7 Bq/kg
(N ¼ 40, range 3–28 Bq/kg) for the green ones. Mean Ra content in red algae is
15 Bq/kg, range 2–39 Bq/kg, which shows similar pattern of natural nuclide
accumulation by the algae species along the Black sea coast.
210 Pb content in all
algae species is in the range 3–40 Bq/kg, which is close to the values of
neighbouring Mediterranean Sea and shows the level of this nuclide from recently
deposited particles.
The radionuclide content in marine ecosystems and especially in algae is in the
limits of published data for the Black Sea and the Mediterranean.
The
137 Cs,
226 Ra and
210 Pb content of the radionuclides has been measured in
sediments and macroalgae located in several geographic zones along the Bulgarian
Black sea coast, during the period from 1991 to 1999. The accumulation capacity
and radionuclide content for different algae species also was determined for three
algae phyla in the marine environment. No great difference was found in nuclide
accumulation in algae, but the red species seem to accumulate nuclides to a higher
degree than the brown and green species.
The data show that macrophytes can be used as reliable indicators for marine
environmental assessment. With this paper we intend to fill the lack of data
concerning radionuclides in sediments and macroalgae along the whole Bulgarian
Black Sea coast. The data can be used as reference levels for further monitoring and
control of the marine ecosystem status (Table 18.5).
Figure 18.10 Nuclide content (Bq/kg) in green and brown algae Figs. 18.11,
18.12, 18.13 and 18.14. The analysis of all alga samples for natural radionuclides
content from
238 U series –
226 Ra and
210 Pb. Showed
226 Ra concentration values in
the range 2–28 Bq/kg for red (mean 15 Æ 2):, for brown 2–17 Bq/kg (mean
9.8 Æ 0.8) and for green 3–18 Bq/kg (mean 9 Æ 1). Accumulation intervals for
226
Ra are close for the two brown and for green Ulva rigida, Clad. vagabunda and Ent.
intestinalis. The
226 Ra mean values in different species can be arranged as follows:
Cer. rubrum > Clad. vagabunda ¼ Cyst. barbata > Cyst. crinita ¼ Ulva
rigida ¼ Ent. intestinalis > Chaetom. gracilis > Callith. corymbosum ¼ Cor.
officinalis.
The obtained
210 Pb average values content in studied algae vary between 4 and
35 Bq/kg (mean 15 Æ 1) for red, 2 and 21 Bq/kg (mean 11 Æ 1) for brown and from
3 to 16 Bq/kg (mean 8 Æ 1) for green algae. If
210 Pb mean values are arranged
depending on algae species, the following order is obtained:
Cer. rubrum > Calith. corymbosum > Cor. officinalis ¼ Cyst. crinita > Chaetom.
gracilis > Ent. intestinalis > Cyst. barbata > Clad. vagabunda > Ulva rigida
318
A. Strezov
combined, the total mean for all brown and green algae is the following:
10 + 1 Bq/kg (N ¼ 40, range 2–25 Bq/kg) for brown species and 8.6 + 0.7 Bq/kg
(N ¼ 40, range 3–28 Bq/kg) for the green ones. Mean Ra content in red algae is
15 Bq/kg, range 2–39 Bq/kg, which shows similar pattern of natural nuclide
accumulation by the algae species along the Black sea coast.
210 Pb content in all
algae species is in the range 3–40 Bq/kg, which is close to the values of
neighbouring Mediterranean Sea and shows the level of this nuclide from recently
deposited particles.
The radionuclide content in marine ecosystems and especially in algae is in the
limits of published data for the Black Sea and the Mediterranean.
The
137 Cs,
226 Ra and
210 Pb content of the radionuclides has been measured in
sediments and macroalgae located in several geographic zones along the Bulgarian
Black sea coast, during the period from 1991 to 1999. The accumulation capacity
and radionuclide content for different algae species also was determined for three
algae phyla in the marine environment. No great difference was found in nuclide
accumulation in algae, but the red species seem to accumulate nuclides to a higher
degree than the brown and green species.
The data show that macrophytes can be used as reliable indicators for marine
environmental assessment. With this paper we intend to fill the lack of data
concerning radionuclides in sediments and macroalgae along the whole Bulgarian
Black Sea coast. The data can be used as reference levels for further monitoring and
control of the marine ecosystem status (Table 18.5).
Figure 18.10 Nuclide content (Bq/kg) in green and brown algae Figs. 18.11,
18.12, 18.13 and 18.14. The analysis of all alga samples for natural radionuclides
content from
238 U series –
226 Ra and
210 Pb. Showed
226 Ra concentration values in
the range 2–28 Bq/kg for red (mean 15 Æ 2):, for brown 2–17 Bq/kg (mean
9.8 Æ 0.8) and for green 3–18 Bq/kg (mean 9 Æ 1). Accumulation intervals for
226
Ra are close for the two brown and for green Ulva rigida, Clad. vagabunda and Ent.
intestinalis. The
226 Ra mean values in different species can be arranged as follows:
Cer. rubrum > Clad. vagabunda ¼ Cyst. barbata > Cyst. crinita ¼ Ulva
rigida ¼ Ent. intestinalis > Chaetom. gracilis > Callith. corymbosum ¼ Cor.
officinalis.
The obtained
210 Pb average values content in studied algae vary between 4 and
35 Bq/kg (mean 15 Æ 1) for red, 2 and 21 Bq/kg (mean 11 Æ 1) for brown and from
3 to 16 Bq/kg (mean 8 Æ 1) for green algae. If
210 Pb mean values are arranged
depending on algae species, the following order is obtained:
Cer. rubrum > Calith. corymbosum > Cor. officinalis ¼ Cyst. crinita > Chaetom.
gracilis > Ent. intestinalis > Cyst. barbata > Clad. vagabunda > Ulva rigida
318
A. Strezov