Forest fires in European Russia: no reasons for radiophobia
After the forest fires in the central part of European Russia in July
and August 2010, a concern was expressed that resuspended radionuclides
from the areas, formerly contaminated due to the Chernobyl accident, can
be transferred by winds to other regions and cause an increase of the
background radiation. This concern has been reinforced by articles in
scientific journals, where questionable statements were made with
references to non-professional publications (mass media, websites of
unclear affiliation, commercial editions) or without any references at
all, e.g. in the volume 1181 of The Annals of the New York Academy of
Sciences (2009) dedicated to the Chernobyl accident (commented in [1]).
For example, the following statement was made without references:
"Chernobyl radionuclides concentrate in sediments, water, plants, and
animals, sometimes 100,000 times more than the local background level."
[2] Another example from the same source: "In territories with a high
density of ground-level radioactive contamination (in soil, water,
vegetation) the hot air resulting from the fires caused radionuclides to
be carried up to a height of 3 km and transported over hundreds of
kilometers (Konoplia et al., 2006)." The referred source (Konoplia et al.,
2006) is not in the reference list of the [2] and was not found. The last
example: "On September 6, 1992, radioactive aerosols lifted by a strong
wind from the 30-km Chernobyl zone reached the vicinity of Vilnius,
Lithuania (about 300 km away) in 5-7 h, where the 137Cs concentration
increased 100-fold (Ogorodnykov, 2002)." The quoted source [3] is largely
a belletristic text. The quotation is correct, but the statement is made
in [3] without references; it is not commented, how the measurements were
made, whether they were reliable or not; there are no figures neither of
initial nor of maximal radioactivity in the affected area. Publications
such as [2], providing no reliable or verifiable information, only foster
radiophobia. It is known that "Chernobyl hysteria" impeded nuclear energy
production in many countries, thus contributing to higher prices for
fossil fuel. Cui prodest scelus, is fecit.
Here follows a brief overview of available information on this theme.
One year after the Chernobyl accident, only about 2 % of the total
radioactivity initally released was remaining in the environment. 10 years
after the accident, less than 1 % remained. A great part of 137Cs, the
main dose-forming Chernobyl radionuclide remaining after the decay of
short-lived isotopes, is adsorbed to the soil matrix [4], thus being
hardly available for resuspension during forest fires. The resuspension,
estimated by modelling of forest fires, involved only around 5 % of total
137Cs in the area of the fire. Radiocesium is relatively weakly
bioaccumulated in wood. Activity concentrations in trees are significantly
lower than in the soil, leaf litter and understorey vegetation. In the
forests around Chernobyl, around 5 % of radionuclides are accumulated in
trees; 20-85% are in the understorey vegetation, the rest being in the
soil [5]. Resuspension coefficients decrease with the time elapsing after
the initial radioactive fallout according to an exponential law [6].
Kasparov et al. [7] concluded on the basis of experimental forest fires
that radionuclide retransfer causes no considerable additional
contamination of an area even under the most unfavourable conditions [7].
All contamination indices diminish drastically with the increasing
distance from the centre of a forest fire. For example, radiocontamination
is 3-5 orders of magnitude lower at 1500 meters from the fire centre, as
compared to 250 meters (at a windspeed 5 m/s) [5]. A non-convection
spreading of an aerosol is accompanied by rapid decrease of airborne
radioactivity and of its fallout with increasing distance from the
resuspension focus. Depending on the weather conditions, the resuspended
radioactivity and its fallout decreases dozens of times at a distance of
100 meters and thousands of times at a distance of several kilometres from
the fire centre (at a windspeed 5 m/s) [7]. The part of radioactivity
involved into a non-convection transfer amounts only to several percents
from the total radioactivity resuspended by a forest fire [7].
Convectional spreading with lifting of the aerosol to a height can prevent
the radiocontamination of an immediately adjacent zone, with a possible
location of the contamination maximum at a distance of 1.5-2 km from the
centre of the forest fire [7]. Note that a transfer of radionuclides by
convection is accompanied by dispersion during vertical displacements of
the aerosol and turbulences. As a result, at a distance of 20 km from the
forest fire, sedimentation from a radioactive aerosol makes only a
negligible addition to the radioactive background [7]. The radionuclide
fallout along the plume axis is negligible in comparison to the existing
contamination [8]. Radiation doses because of forest fires on
radiocontaminated territories are discussed only for firemen exposed in
the affected area [5,8] and personnel within the Chernobyl zone [5].
Considering the above, forest fires in the Chernobyl area bear no risk of
significant radiocontamination today.
References
1. Jargin SV. Overestimation of Chernobyl consequences: Poorly
substantiated information published. Radiat Environ Biophys 2010; DOI:
10.1007/s00411-010-0313-1.
2. Yablokov AV, Nesterenko VB, Nesterenko AV. 8. Atmospheric, water,
and soil contamination after Chernobyl. Ann N Y Acad Sci. 2009;1181:223-
36.
3. Ogorodnykov BI. Chernobyl: Fifteen years later. In: Chernobyl:
duty and courage (in Russian) Moscow, 2002; Volume 1, Chapter 2. Available
at: http://www.iss.niiit.ru/book-4/glav-2-24.htm (accessed 19/09/2010).
4. Smith J, Beresford NA. Chernobyl - catastrophe and consequences.
Chichester: Springer, 2005.
5. Azarov SI. Atmospheric contamination by 137Cs during forest fires
in the Chernobyl area (in Russian with English summary). Radiats Biol
Radioecol. 1996;36(4):506-15.
6. Budyka AK, Ogorodnikov BI. Effect of some natural processes on the
formation and characteristics of aerosols in regions polluted with
radionuclides (in Russian with English summary). Radiats Biol Radioecol.
2001;41(6):695-9.
7. Kashparov VA, Lundin SM, Kadygrib AM, et al. Radio-ecological and
hygienic assessment of consequences of forest fires in the areas polluted
during the Chernobyl accident (in Russian with English summary). Gig
Sanit. 2001;(1):30-5.
8. Yoschenko VI, Kashparov VA, Protsak VP, et al. Resuspension and
redistribution of radionuclides during grassland and forest fires in the
Chernobyl exclusion zone: part I. Fire experiments. J Environ Radioact.
2006;86(2):143-63.
Rapid Response:
Forest fires in European Russia: no reasons for radiophobia
After the forest fires in the central part of European Russia in July
and August 2010, a concern was expressed that resuspended radionuclides
from the areas, formerly contaminated due to the Chernobyl accident, can
be transferred by winds to other regions and cause an increase of the
background radiation. This concern has been reinforced by articles in
scientific journals, where questionable statements were made with
references to non-professional publications (mass media, websites of
unclear affiliation, commercial editions) or without any references at
all, e.g. in the volume 1181 of The Annals of the New York Academy of
Sciences (2009) dedicated to the Chernobyl accident (commented in [1]).
For example, the following statement was made without references:
"Chernobyl radionuclides concentrate in sediments, water, plants, and
animals, sometimes 100,000 times more than the local background level."
[2] Another example from the same source: "In territories with a high
density of ground-level radioactive contamination (in soil, water,
vegetation) the hot air resulting from the fires caused radionuclides to
be carried up to a height of 3 km and transported over hundreds of
kilometers (Konoplia et al., 2006)." The referred source (Konoplia et al.,
2006) is not in the reference list of the [2] and was not found. The last
example: "On September 6, 1992, radioactive aerosols lifted by a strong
wind from the 30-km Chernobyl zone reached the vicinity of Vilnius,
Lithuania (about 300 km away) in 5-7 h, where the 137Cs concentration
increased 100-fold (Ogorodnykov, 2002)." The quoted source [3] is largely
a belletristic text. The quotation is correct, but the statement is made
in [3] without references; it is not commented, how the measurements were
made, whether they were reliable or not; there are no figures neither of
initial nor of maximal radioactivity in the affected area. Publications
such as [2], providing no reliable or verifiable information, only foster
radiophobia. It is known that "Chernobyl hysteria" impeded nuclear energy
production in many countries, thus contributing to higher prices for
fossil fuel. Cui prodest scelus, is fecit.
Here follows a brief overview of available information on this theme.
One year after the Chernobyl accident, only about 2 % of the total
radioactivity initally released was remaining in the environment. 10 years
after the accident, less than 1 % remained. A great part of 137Cs, the
main dose-forming Chernobyl radionuclide remaining after the decay of
short-lived isotopes, is adsorbed to the soil matrix [4], thus being
hardly available for resuspension during forest fires. The resuspension,
estimated by modelling of forest fires, involved only around 5 % of total
137Cs in the area of the fire. Radiocesium is relatively weakly
bioaccumulated in wood. Activity concentrations in trees are significantly
lower than in the soil, leaf litter and understorey vegetation. In the
forests around Chernobyl, around 5 % of radionuclides are accumulated in
trees; 20-85% are in the understorey vegetation, the rest being in the
soil [5]. Resuspension coefficients decrease with the time elapsing after
the initial radioactive fallout according to an exponential law [6].
Kasparov et al. [7] concluded on the basis of experimental forest fires
that radionuclide retransfer causes no considerable additional
contamination of an area even under the most unfavourable conditions [7].
All contamination indices diminish drastically with the increasing
distance from the centre of a forest fire. For example, radiocontamination
is 3-5 orders of magnitude lower at 1500 meters from the fire centre, as
compared to 250 meters (at a windspeed 5 m/s) [5]. A non-convection
spreading of an aerosol is accompanied by rapid decrease of airborne
radioactivity and of its fallout with increasing distance from the
resuspension focus. Depending on the weather conditions, the resuspended
radioactivity and its fallout decreases dozens of times at a distance of
100 meters and thousands of times at a distance of several kilometres from
the fire centre (at a windspeed 5 m/s) [7]. The part of radioactivity
involved into a non-convection transfer amounts only to several percents
from the total radioactivity resuspended by a forest fire [7].
Convectional spreading with lifting of the aerosol to a height can prevent
the radiocontamination of an immediately adjacent zone, with a possible
location of the contamination maximum at a distance of 1.5-2 km from the
centre of the forest fire [7]. Note that a transfer of radionuclides by
convection is accompanied by dispersion during vertical displacements of
the aerosol and turbulences. As a result, at a distance of 20 km from the
forest fire, sedimentation from a radioactive aerosol makes only a
negligible addition to the radioactive background [7]. The radionuclide
fallout along the plume axis is negligible in comparison to the existing
contamination [8]. Radiation doses because of forest fires on
radiocontaminated territories are discussed only for firemen exposed in
the affected area [5,8] and personnel within the Chernobyl zone [5].
Considering the above, forest fires in the Chernobyl area bear no risk of
significant radiocontamination today.
References
1. Jargin SV. Overestimation of Chernobyl consequences: Poorly
substantiated information published. Radiat Environ Biophys 2010; DOI:
10.1007/s00411-010-0313-1.
2. Yablokov AV, Nesterenko VB, Nesterenko AV. 8. Atmospheric, water,
and soil contamination after Chernobyl. Ann N Y Acad Sci. 2009;1181:223-
36.
3. Ogorodnykov BI. Chernobyl: Fifteen years later. In: Chernobyl:
duty and courage (in Russian) Moscow, 2002; Volume 1, Chapter 2. Available
at: http://www.iss.niiit.ru/book-4/glav-2-24.htm (accessed 19/09/2010).
4. Smith J, Beresford NA. Chernobyl - catastrophe and consequences.
Chichester: Springer, 2005.
5. Azarov SI. Atmospheric contamination by 137Cs during forest fires
in the Chernobyl area (in Russian with English summary). Radiats Biol
Radioecol. 1996;36(4):506-15.
6. Budyka AK, Ogorodnikov BI. Effect of some natural processes on the
formation and characteristics of aerosols in regions polluted with
radionuclides (in Russian with English summary). Radiats Biol Radioecol.
2001;41(6):695-9.
7. Kashparov VA, Lundin SM, Kadygrib AM, et al. Radio-ecological and
hygienic assessment of consequences of forest fires in the areas polluted
during the Chernobyl accident (in Russian with English summary). Gig
Sanit. 2001;(1):30-5.
8. Yoschenko VI, Kashparov VA, Protsak VP, et al. Resuspension and
redistribution of radionuclides during grassland and forest fires in the
Chernobyl exclusion zone: part I. Fire experiments. J Environ Radioact.
2006;86(2):143-63.
Competing interests: No competing interests