Radionuclides from the Fukushima accident in the air over Lithuania:measurement and modelling approaches

G. Lujanien _e a,*, S. By�cenkien _e a, P.P. Povinec b, M. Gera b

a Environmental Research Department, SRI Center for Physical Sciences and Technology, Savanoriu 231, 02300 Vilnius, Lithuaniab Faculty of Mathematics, Physics and Informatics, Comenius University, Bratislava, Slovakia

a r t i c l e i n f o

Article history:

Received 25 August 2011

Received in revised form

30 November 2011

Accepted 5 December 2011

Available online 27 December 2011

Keywords:

Fukushima accident

Aerosols

Iodine-131

Caesium-134,137

Plutonium-238,239þ240

a b s t r a c t

Analyses of 131I, 137Cs and 134Cs in airborne aerosols were carried out in daily samples in Vilnius,

Lithuania after the Fukushima accident during the period of MarcheApril, 2011. The activity concen-

trations of 131I and 137Cs ranged from 12 mBq/m3 and 1.4 mBq/m3 to 3700 mBq/m3 and 1040 mBq/m3,

respectively. The activity concentration of 239,240Pu in one aerosol sample collected from 23 March to 15

April, 2011 was found to be 44.5 nBq/m3. The two maxima found in radionuclide concentrations were

related to complicated long-range air mass transport from Japan across the Pacific, the North America

and the Atlantic Ocean to Central Europe as indicated by modelling. HYSPLIT backward trajectories and

meteorological data were applied for interpretation of activity variations of measured radionuclides

observed at the site of investigation. 7Be and 212Pb activity concentrations and their ratios were used as

tracers of vertical transport of air masses. Fukushima data were compared with the data obtained during

the Chernobyl accident and in the post Chernobyl period. The activity concentrations of 131I and 137Cs

were found to be by 4 orders of magnitude lower as compared to the Chernobyl accident. The activity

ratio of 134Cs/137Cs was around 1 with small variations only. The activity ratio of 238Pu/239,240Pu in the

aerosol sample was 1.2, indicating a presence of the spent fuel of different origin than that of the

Chernobyl accident.

� 2011 Elsevier Ltd. All rights reserved.

1. Introduction

On March 11, 2011 a strong earthquake followed by high

tsunami and fires damaged three reactors and a fuel pond at the

Fukushima Dai-ichi Nuclear Power Plant (NPP) in Japan with

releases of radionuclides to the atmosphere and the sea. According

to the NISA (Nuclear and Industrial Safety Agency) report from

1.3 � 1017 Bq to 1.5 � 1017 Bq of 131I and about 6.1 � 1015 to

1.3 � 1016 Bq of 137Cs were released to the atmosphere (NISA, 2011;

Chino et al., 2011). The consequences of this accident at the

beginning estimated as level 4 were raised to themaximum level of

7 on the INES (International Nuclear and Radiological Event Scale)

scale (IAEA, 2011), although the amount of discharged radioactive

materials comprised approximately 10% of the Chernobyl accident

only. Measurements carried out at Tokushima (about 700 km

southwest from the Fukushima NPP) indicated the maximum

activity concentration of particulate 131I in the air of w3 mBq/m3

which was observed on 6 April (Fushimi et al., 2011).

Worldwide monitoring activities started immediately after the

announcement of large radionuclide releases from the Fukushima

NPP. The particulate 131I activities of 4.4 mBq/m3 were detected on

19e21 of March in Seattle (USA) (Diaz Leon et al., 2011). According

to the CTBTO (Comprehensive Test-Ben Treaty Organization) data

the first signs of diluted airborne activities appeared over Europe

after 12 days of the Fukushima accident (Wotawa, 2011). The

elevated levels of radionuclides on aerosols derived from the

Fukushima NPP were detected at several sampling stations in Spain

(Lozano et al., 2011), Germany (Pittauerová et al., 2011), Greece

(Manolopoulou et al., 2011), Russia (Bolsunovsky and Dementyev,

2011). The most comprehensive radionuclide data over the

Europe has been compiled by Masson et al. (2011).

Anthropogenic radionuclides were introduced into the terres-

trial and marine environments primarily after the atmospheric

nuclear weapon tests carried out by the United States and the

former Soviet Union from the 1940s to the early 1960s (Livingston

and Povinec, 2002). Another source of anthropogenic radionuclides

is related to nuclear accidents. The most severe of them was the

Chernobyl accident when among other radionuclides about

1760 PBq of 131I, 47 PBq of 134Cs and 85 PBq of 137Cs were released

into the environment (IAEA, 2006). The consequences of the* Corresponding author. Tel.: þ370 5 2644856; fax: þ370 5 2602317.

E-mail address: lujaniene@ar.fi.lt (G. Lujanien _e).

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Journal of Environmental Radioactivity

journal homepage: www.elsevier .com/locate/ jenvrad

0265-931X/$ e see front matter � 2011 Elsevier Ltd. All rights reserved.

doi:10.1016/j.jenvrad.2011.12.004

Journal of Environmental Radioactivity 114 (2012) 71e80

Chernobyl accident on the environment and human health were

estimated as the worst in the nuclear accident history by its rating

to the highest level 7 on the INES scale. Until 12th March, 2011 the

second largest accident was the Kyshtym accident which occurred

on 29th September,1957, when due to problems in a cooling system

and followed explosion about 7.4� 105 TBq of radioactive materials

were released into the environment. As a result of this accident,

more than 10,000 people received significant radiation doses (Hu

et al., 2010).

The aim of the present study has been to estimate activity

concentrations of Fukushima airborne radioactive aerosols over

Lithuania with special emphasis on particle transport from

Fukushima to Europe (preliminary results were published by

Lujanien _e et al., 2011), and to compare the obtained results with

data gathered during the investigations of the Chernobyl accident.

2. Samples and methods

2.1. Sampling

The ground level air samples were collected in a forested area on

the outskirts of Vilnius (54�420N, 25�300E). Perchlorvinyl filters FPP-

15 (w1 m2 surface) were exposed in a special building with blind

walls at the height of 1 m above the ground. High volume samplers

with flow rates from 2400m3/h to about 6000m3/h were used. The

sampling was carried out continuously. 131I, 137Cs and 134Cs were

measured by gamma-ray spectrometry using a HPGe detector

(relative efficiency of 42%, resolution of 1.9 keV at 1.33Mev). The

precision of 137Cs measurements by gamma-spectrometry was

better than �7% at 2s level.

The radiochemical analyses of Am and Pu were performed on

monthly samples (total volume w2.0 � 106 m3) of aerosol ashes

(about 30 g), which were dissolved in strong acids (HNO3, HCl, HF

and HClO4). The TOPO/cyclohexane extraction and radiochemical

purification using UTEVA, TRU and TEVA resins (100e150 mm)were

used for separation of Am and Pu isotopes. 242Pu and 243Am were

used as yield tracers in the separation procedure (Lujanien _e et al.,

2006). The alpha-spectrometry measurements of Pu and Am

isotopes deposited on stainless-steel discs were carried out with

the Alphaquattro (Silena) spectrometer. Accuracy and precision of

analysis were tested using reference materials IAEA-135, NIST SRM

No 4350B and 4357, as well as in intercomparison exercises, orga-

nized by the Risø National Laboratory (Denmark), and the National

Physical Laboratory (UK). The precision of Pu and Am measure-

ments was better than �8% and �10%, respectively (at 2s level).

2.2. Modelling

The transport of radionuclides was simulated using a Lagrangian

particle model which calculates trajectories of particles that follow

the instantaneousflow in the particle position (Závodský, 2011). The

output particle velocity is a sum of deterministic velocity and semi-

random stochastic velocity, generated by the Monte Carlo tech-

nique. The probability density function for the random component,

which simulates the atmospheric turbulence, is dependent on the

state of the atmospheric boundary layer. The model also takes into

account the radioactive decay of particles (e.g. in the case of 131I), as

well as their scavenging by dry and wet deposition. For the mete-

orological input, the Integrated Monitoring System e IMS Model

Suite Lagrangian dispersion model (MicroStep-MIS, 2011) has been

used. It calculates the spreading of radioactive materials with

special regard to changes in atmospheric conditions, especially

changes in wind direction. The meteorological input for the

dispersionmodelwas a time sequence analysis of atmospheric state

in GRIB format (WMO, 2009). The GFS global weather model was

used in simulation time span from 12 March to 27 March, 2011. The

3Dwind (u, v, vertical velocity) at upper airmodel levelswas needed

to simulate dispersion due to large-scale winds.

A characterization of radionuclide activities with respect to

categorized air mass backward trajectories was carried out for

estimation of potential location of the radioactivity source. Air mass

backward trajectories were generated using the Hybrid Single-

Particle Lagrangian Integrated Trajectory (HYSPLIT4) model

(Rolph, 2011) with the Final Analyses (FNL, year 2011) and the

Global Data Assimilation System (GDAS) meteorological databases

at the NOAA Air Resources Laboratory server (Rolph, 2011).

3. Results and discussion

3.1. Modelling of the Fukushima plume

For the assessment of contamination after the accident and

prediction of radioactive particle transport the Lagrangian model-

ling was applied. In order to describe the atmospheric processes

realistically, the vertical velocity, particle dissipation and turbu-

lence during the particle trajectory were considered. A single

release of 1015 Bq of 137Cs, which occurred on March 12, 2011 from

damaged Fukushima NPPwas analyzed. The initial plume height, as

a result of initial vertical velocity and buoyancy, was kept to be at

2000e3000 m. The meteorological data and simulated trajectories

revealed that the arrival times of particles released on 11 March,

2011 and 12 March, 2011 were different, and the particles were

transported at different altitudes. It was also obvious that the jet

stream affected the transport of emitted particles at upper atmo-

spheric levels. Examples of the trajectories simulated using the

Lagrangian dispersion model show (Fig. 1) that the first signs of

Fukushima released radionuclides could be detected in the Euro-

pean countries (e.g. Island) on 20 March, 2011. The performed

simulation indicated that particles released on 11 March, 2011

mainly appeared over Europe on 850 hPa on 13 April, 2011, at

700 hPa on 30 March, 2011 and at 500 hPa on 20 March, 2011.

Similar situation was observed for particles released on 12 March,

2011which arrived to Europe at 700 hPa on 1 April, 2011, at 500 hPa

on 21 March, 2011, and the particles at 850 hPa did not reach the

European territory. The particle arriving times are in a reasonable

agreement with experimental radionuclide data obtained for Vil-

nius (Lithuania), as discussed later.

3.2. Radionuclide data

The time course of 131I (aerosol component) and 137Cs concen-

trations measured in MarcheApril of 2011 in Vilnius is shown in

Fig. 2, comparedwith the course of the cosmogenic 7Be. The activity

concentrations of 131I and 137Cs ranged from 2 to 3800 mBq/m3 and

from 0.2 to 1070 mBq/m3, respectively. The first traces of 131I in

aerosol filters in Vilnius were found on 23 March. A considerable

increase in the 131I activity concentrations (up to about 2.4 mBq/

m3) was observed during the period of 28 Marche1 April. The

second maximumwas detected on 3e4 April, when up to 3.7 mBq/

m3 of 131I was measured in the atmosphere. Activities of 137Cs in

aerosol during this period increased up to 0.5mBq/m3 and 1.0 mBq/

m3, respectively. In addition to 131I and 137Cs, traces of other

radionuclides were detected in the aerosol filters as well.

Their concentrations in the most active sample collected on 3e4

April 2011 14:00e06:50 UTC were: 132I e 0.12 � 0.01 mBq/m3,132Te e 0.13 � 0.01 mBq/m3, 129Te e 0.40 � 0.04 mBq/m3,129mTee0.75 � 0.25 mBq/m3 and 136Cs e 0.080 � 0.0080mBq/m3.

The variations in the activity concentrations of studied radio-

nuclides can be due to the different arrival time of radioactive

particles predicted by the Lagrangian modelling. The particles

G. Lujanien _e et al. / Journal of Environmental Radioactivity 114 (2012) 71e8072

released on 11 March, 2011, and according to the prognosis they

should appear over the Europe at 850 hPa on 13 April, 2011, were

not detected in Vilnius. The particles arriving at 700 hPa were

detected on 30 March, 2011, while the particles at 500 hPa

appearing on 21 March, 2011, were detected in Vilnius on 22e23

March. The particles released on 12 March, 2011 and which were

expected over Europe at 700 hPa on 1 April, 2011 were not detected

at our sampling station, whereas a clear maximum in activity

concentrations of 131I, 134Cs and 137Cs was observed on 4 April, 2011.

The particles that were supposed to be over Europe at 500 hPa on

24 March, 2011 were detected with one day delay on 25 March,

2011. It seems therefore that the Fukushima plumewhich arrived to

Europe at high altitudes did not necessarily reach the near-surface

level.

On the other hand, meteorological conditions at the site

(e.g. precipitation) could affect the activity concentrations. The

amount of precipitation given in Fig. 2 revealed that it could have

a certain effect on changes in activity concentrations of studied

radionuclides. However, no correlationwas found between the 131I,137Cs and 7Be activity concentrations and the amount of precipi-

tation (R ¼ �0.01, �0.09 and �0.07, respectively), indicating that

the influence of precipitation was in general negligible. Nonethe-

less, from data shown in Fig. 2 it can be seen that the increase in 131I

and 137Cs activity concentrations was accompanied by the rise of7Be activities. In addition, 131I and 137Cs activities well correlated

(R¼ 0.69 and R¼ 0.75, respectively) with the activity concentration

of 7Be (Fig. 3).

The cosmogenic 7Be (half-life of 53.3 days) is mainly produced in

the lower stratosphere (w70%) and the rest in the upper tropo-

sphere. It has been widely used to study vertical air mass transport

Fig. 1. Particles spacing on 20 March, 2011 at 12:00 UTC (top) and on 27 March, 2011 at 18:00 UTC (bottom); shades of red indicate particles in the bottom layer, up to 3 km; black to

dark blue indicate the middle layer, up to 6 km height; and light blue indicates the upper layer; the trajectories were simulated using the Lagrangian dispersion model (time of the

particles release was on 12 March 2011). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

24 26 28 30 1 3 5 7 9 11 13

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

March April 2011

137Cs

R=-0.09 (n=29)131

I

R=-0.10 (n=29)

137C

s,1

31I,

µB

qm

3

0

2

4

6

8

10

7Be, m

Bq

/m3

Pre

cip

itatio

n, m

m;

Precipitation

7Be

R=-0.07 (n-29)

Fig. 2. Activity concentration of 131I, 137Cs and 7Be in aerosol samples as well as

precipitation amount in Vilnius in 2011.

G. Lujanien _e et al. / Journal of Environmental Radioactivity 114 (2012) 71e80 73

(e.g. Lujanas and Lujanien _e, 2007). An increase in the 7Be activity

concentrations in summer and autumn season was explained by

a vertically downward transport within the troposphere (Koch

et al., 1996) and by a stratosphere-troposphere exchange (Jordan

et al., 2003; Land and Feichter, 2003). The high 7Be activity

concentrations in the surface air were also interpreted by the

downward and upward atmospheric flows in the troposphere

caused by a pair of travelling anticyclone and extra tropical cyclone

that passes over Japan in spring and autumnwith a period of a few

days (Yoshimori, 2005). It was supposed that the air of low

temperature flows downward from convergence in the Rossby

waves to divergence in the surface anticyclone, and the warm air

moves upward from convergence in the surface cyclone to diver-

gence in the Rossby waves. In these studies an increase in the

activity concentrations in the near-surface atmosphere was asso-

ciated with downward movements of air masses. Thus, the positive

correlation between the anthropogenic radionuclides and 7Be

(Fig. 3) can be an indication of their arrival from the upper layers of

the troposphere.

On the other hand, short-lived radon decay products, such as the

terrigenous 210Pb, 212Pb and 214Pb can also be used as atmospheric

tracers to study air masses transport (Sheets and Lawrence, 1999).

The main source of 212Pb (half-life of 10.6 h) in the air is 220Rn (half-

life of 54 s) exhalation from the earth’s surface, therefore 212Pb

activity concentrations reflect local conditions (at height of about

1 km), contrary to 222Rn (half-life of 3.82 d) progenies 214Pb

(half-life of 26.8 min) and 210Pb (half-life of 22.3 y). The residence

times of radon decay products in the ambient air were estimated to

be similar to that of 7Be (about 8 days). About 76% of the 214Pb

activity and 67% of the 212Pb activity were usually associated with

aerosol particles in the 0.08e1.4-mm size range, though a small shift

in the aerosol size distribution was observed for 214Pb

(Papastefanou, 2009). Seasonal variations of 212Pb and 210Pb

isotopes were found to be distinctly different in the lower atmo-

sphere while the behaviour of 214Pb was similar to that of 210Pb. It

was concluded therefore that airborne concentrations of 212Pb,

contrary to those of 210Pb could be strongly influenced by local

emissions (Sheets and Lawrence, 1999). This behavior and shift in

the size distribution can be attributed to the variation in half-lives

of Pb isotopes and their parents. Both parents are gaseous species

but their different half-life under particular local conditions such as

exhalation, mixing height and intensity can result in their various

vertical and horizontal transports. 222Rn of longer half-life has

a higher potential to be more widely distributed vertically and

horizontally. On the other hand, due to different half-lives of Pb

isotopes, they can serve for indication of events occurring on

different time scales. Kownacka (2002) reported that activity

concentrations of 210Pb were almost constantly distributed above

1 km, and did not decrease with altitudes. An increase in 210Pb and

other natural radionuclide concentrations in the stratosphere was

also observed after the large volcanic eruptions. Abe et al. (2010)

showed that distributions of the 7Be and 210Pb nuclides were

uniform in the range of a few hundred kilometers in the horizontal

direction and up tow1 km height, whereas 212Pb activity concen-

trations varied greatly depending on the geographical location and

altitude of the observation site. The recent studies indicated

a similar behavior of 7Be and 210Pb, and that they cannot be used as

independent tracers to study atmospheric processes. Although the

behavior of 212Pb and 214Pb is not fully understood yet, they can be

used as independent atmospheric traces. A weak correlation was

found in 7Be and 212Pb records (0.39), while no correlation was

observed for 7Be and 214Pb (�0.16), indicating different sources of

Pb isotopes. The 212Pb and 214Pb records may therefore indicate

different atmospheric processes. Most probably 212Pb is an indi-

cator of horizontal transport at lower heights (up to 1 km),

however, a weak correlation showed that this transport was

limited. On the other hand, 214Pb represents short time events at

our site. An increase in the activity ratios of 7Be/212Pb and 7Be/214Pb,

accompanied by an increase in 137Cs and 131I activity concentrations

observed during the studied periodmay indicate that the dominant

source of Fukushima originated radionuclides at our site was at

higher altitudes. Therefore, an increase in the 7Be/212Pb and7Be/214Pb activity ratios in this case can be used for an indication of

the downward air mass transport.

The activity concentration of 137Cs as well as the 134Cs/137Cs,7Be/212Pb and 7Be/214Pb activity ratios in aerosol samples in the

studied episode after the Fukushima accident are presented in

Fig. 4. The 134Cs/137Cs activity ratio in Vilnius was close to 1 (N¼ 30,

Mean ¼ 0.782, S.D. ¼ 0.345, Median ¼ 0.938). In samples collected

on 24March, and from 26 to 27March, the activity concentration of134Cs was below the detection limit. In the most active sample

collected on 3e4 April the 134Cs/137Cs activity ratio was equal to

1.00 � 0.05.

Fig. 5 shows the wind speed and wind vectors indicating the jet

stream at 500 hPa for 24e25 March which affected the transport of

the Fukushima plume to Europe. The strong meanders on the jet

stream resulted in the downward air mass transport, as it is indi-

cated by an increase in the 7Be activity concentrations (Fig. 2), as

well as by an increase in the activity ratios of 7Be/212Pb and7Be/214Pb (Fig. 4). A similar increase in the activity concentrations of131I, 137Cs and 7Be, together with enhanced activity ratios of7Be/212Pb and 7Be/214Pb observed on 23, 24, 27 and 31 March, as

0 2000 4000 6000 8000

0

200

400

600

800

1000

1200

7Be, µBq/m

3

137C

s,

µB

q/m

3

137Cs

R = 0.75 (n=29)0

1000

2000

3000

4000

131I, µ

Bq

/m3

131I

R = 0.69 (n= 29)

Fig. 3. 137Cs and 131I activity concentrations plotted against the 7Be activity concen-

tration in aerosol samples collected during the Fukushima plume episode.

24 26 28 30 1 3 5 7 9 11 13

0.1

1

10

100

1000

March April 2011

137Cs

137C

sµB

q/m

3

0.01

0.1

1

10

100 Ratio

of ra

dio

nu

clid

es7

Be/212

Pb7Be/

214Pb

134Cs/

137Cs

Fig. 4. Activity concentration of 137Cs and 134Cs/137Cs, 7Be/212Pb and 7Be/214Pb activity

ratios in aerosol samples in Vilnius in 2011.

G. Lujanien _e et al. / Journal of Environmental Radioactivity 114 (2012) 71e8074

well as on 4 April, can be interpreted as a downward transport of air

masses carrying the Fukushima plume radionuclides from higher

layers of the troposphere (Figs. 2 and 4). The low relative humidity

over the sampling site (Fig. 5) observed at 500 hPa on 4 April can

serve as an additional confirmation of air flow from the upper levels

of the atmosphere.

A slightly different pattern of the radionuclide record observed

from 28 to 31 March can be explained by the effect of precipitation

(Fig. 2) that could remove the Fukushimaderived radionuclides and/

or preferably wash out aerosol particles carrying cosmogenic 7Be

due to their different chemical composition and size distribution

(Lujanien _e et al., 1998; Lujanien _e, 2000, 2003). Another possible

explanation can be variations of the transport altitudes and arrival

time of the Fukushima radioactive particles. The NOAA HYSPLIT

model (Draxler and Rolph, 2011) was used to assess the transport

pattern and to explain the deviation in radionuclide activity

concentrations found in Vilnius. A large number of air mass back-

ward trajectorieswere calculated over the time of interest. Themost

typical trajectories, capable to provide a proper interpretation of the

observed radionuclide variations (Fig. 6), show backward air mass

transport starting at 500 (red triangles), 3000 (blue squares), and

7000m (green circles) above the ground level (AGL). Trajectories are

labelled every 24 h by a filled symbol. The vertical projection of the

trajectories with time is shown in the panel below the map. The air

mass backward trajectories calculated for 30 March can serve as an

example of complicated pathway of air masses (Fig. 6A). The back-

ward trajectories were calculated for three 500, 3000 and 5000 m

AGL for 315h. The airmasses at 500mwere caught up into a cyclonic

system,while airmasses at 3000 and 5000mwere lifted and rapidly

transported over the North America to Europe. It seems that

radioactive particles have had a greater chance of being transported

at higher atmosphere levels. They can be removed in the lower layer

of the atmosphere due to various reasons, e.g. rainfall characteris-

tics, fog formation or growth of aerosol particles and their deposi-

tion. Thus, there was a higher probability that activity

concentrations of radionuclides found on 28e31 March were

diluted by clean air masses, and/or they were reduced by precipi-

tation in the near-surface level and/or marine boundary layer

(w1 km) during their long-range transport from Japan.

The air masses which arrived on 1e2 April were affected both by

cyclone and anticyclone systems, and they brought rather clean air

to Europe (Fig. 6B). During these days the activity concentrations of131I and 137Cs dropped to 150e190 mBq/m3 and 8e16 mBq/m3,

respectively (Fig. 2), however, on 4 April they again rose up to

2280e3690 mBq/m3 and 609e1026 mBq/m3, respectively. It should

be noted that an increase in radionuclide activities was detected in

the most European countries (Masson et al., 2011).

In order to explain the origin of the second maximum in the

radionuclide courses (Fig. 2), the air mass backward trajectories

were calculated for 1000, 3000 and 5000 m heights. The results

showed (i) a direct transfer from Fukushima across the Pacific

Ocean, (ii) a transport through the North Pole, and (iii) a pathway

through the Greenland and Iceland (Fig. 6. C). The air masses at

1000 and 5000 mwere rapidly transported, while the air masses at

3000 m exhibited rather slow transport, and most probably these

air masses provided a transfer of contaminated air already present

over the Greenland. These results are in good agreement with the

prognoses made by the CTBTO (Wotawa, 2011) explaining two

maxima of the Fukushima plume observed over Europe.

We can conclude that themeasured activityconcentrations at the

site of investigation resulted from a complicated air mass transport,

arrival time, arrival height, meteorology and downward air mass

transport. The downward transport was found to be an important

factor affecting activity concentrations in the surface air. Higher

activities can be transported over long distances at higher altitudesFig. 5. The wind speed, wind vectors and relative humidity at 500 hPa for 24e25

March and 3 April, 2011.

G. Lujanien _e et al. / Journal of Environmental Radioactivity 114 (2012) 71e80 75

Fig. 6. Backward trajectories of air masses transport ending on 30 March, 1 April and 4 April, 2011 in Vilnius.

G. Lujanien _e et al. / Journal of Environmental Radioactivity 114 (2012) 71e8076

with higher probability, due to the precipitation effect and rather

short residence time ofwater soluble aerosols in the boundary layer.

3.3. Comparison with the Chernobyl accident

The consequences of the Fukushima accident were estimated to

be close to the Chernobyl accident according to the given level 7 on

the INES scale (IAEA, 2011). The long-term radiological impact of the

Chernobyl accidenton the environment andhumansdue to released

radioactivity, migration, resuspension of deposited radionuclides

has been studied over 20 years. During the accident, and the post

Chernobyl period, many measurements of gamma, beta and alpha-

emitters in aerosol samples were carried out in Vilnius (Lujanas

et al., 1994; Lujanien _e et al., 1997, 1999, 2009). A wide spectrum of

radionuclides and “hot particles”were detected in Vilnius following

the Chernobyl accident, when activity concentrations were there

higher by 4 orders of magnitude as compared to the Fukushima

accident. The maximum activities in Vilnius during the first week

after the Chernobyl accident were 45.2 Bq/m3 for 131I (aerosol

fraction) and 27.9 Bq/m3 for 137Cs. The 132Te and 103Ru activity

concentrations inAprileMay,1986 ranged from0.1Bq/m3 to51.0Bq/

m3 and from 0.1 Bq/m3 to 20.3 Bq/m3, respectively (Fig. 7).

In the Chernobyl plume Zr, Nb, Ru and Ce isotopeswere detected

in the air as well. In addition, the presence of “hot particles” of

0.37e22.2 mm in size carrying beta-emitters, and “hot particles” of

0.7e2 mm containing alpha-emitters (233U, 234U, 235U, 238Pu, 239Pu,240Pu, 241Am, 242Cm, 244Cm) in 1986 were also found in aerosol

filters collected in Vilnius. The activity ratio of 238Pu/239,240Pu

varied from 0.44 to 0.5 and the atom ratio of 240Pu/239Pu ranged

from 0.41 to 0.42. The high activities detected in Vilnius after the

Chernobyl accident were explained by quite close location

(480 km) of the site.

Furthermore, the Chernobyl accident resulted in contamination

of large areas of the Earth’s surface in Europe including six million

ha of forested land of the Ukraine, Belarus and Russia (De Cort et al.,

1998). The 137Cs surface deposition (Fig. 8) exceeded 1480 kBq/m2

(0.03% of the European territory). The prediction of 137Cs surface

deposition after the Fukushima accident was made using

a numerical atmospheric chemistry/transport model Polyphemus/

Polair3D, and compared with contamination of Europe after the

Chernobyl accident (Winiarek et al., 2011). The results indicated

obvious differences in the consequences of the Chernobyl and

Fukushima accidents, especially at the level of highly contaminated

territories. However, a contamination of the marine environment

and a deposition to the bottom sediments were not taken into

account in this model. It is expected that the main radiological

problems will arise from contaminated seafood, while the atmo-

spheric deposition will again trigger discussions on the impact of

low-level radiation doses on the public.

Areas with high Chernobyl 137Cs ground depositions located

close to Lithuania have been a source of the secondary contami-

nation due to the forest fires and soil resuspension for a long time

(Lujanien _e et al., 2009). The transport of aerosol particles, which

derived from resuspension and/or forest fires in 1997e2001 and

2005e2006 was modelled using the HYSPLIT. The backward

trajectories were calculated for 4 selected sectors for 72 h at the

heights of 20, 500 and 1000 m AGL (Fig. 8). However, not all

calculated trajectories were possible to assign to a particular sector.

Very complicated trajectories that did not match any sector were

associated with sector 0.

In both studied periods a weak correlation between the 137Cs

activity concentration and height (R ¼ 0.28 (20 m), 0.32 (500 m),

and 0.31 (1000 m) in 1997e2001; and for 2005e2006 R ¼ 0.41

(20 m), 0.49 (500 m), and 0.49 (1000 m)) was found for the Cher-

nobyl sector, while for other sectors no correlation was observed. A

dissimilar behaviour of Pu isotopes was explained by their different

volatility as compared to Cs ones. This is again in good agreement

with results obtained in 2005e2006 (Fig. 9) where 239,240Pu

activities ranged from 2 to 49 nBq/m3, with maxima observed in

May (29 and 49 nBq/m3, respectively), and they obviously derived

from soil resuspension. The 241Am activity concentrations varied

from 1 to 25 nBq/m3 and the highest values were also detected in

May. Variations in the 241Am/239,240Pu activity ratios from 0.27 to

0.65 were found in the analyzed samples with the average value

of 0.44.

The 238Pu/239,240Pu activity ratios in aerosol samples collected in

Vilnius during the Chernobyl accident were in the range 0.44e0.50,

while the 240Pu/239Pu atom ratios in the same samples ranged from

0.41 to 0.42. The 240Pu/239Pu atom ratios in monthly samples in

Vilnius in 1995e2003 varied from 0.14 to 0.40, whereas in samples

collected during forest fires the ratio was between 0.19 and 0.23. In

addition, an exponential decrease in the 240Pu/239Pu atom ratio

from 0.30 to 0.19 (mean values) was observed during 1995e2003.

The characteristic 238Pu/239,240Pu activity ratio of global fallout is

0.03, while that of the Chernobyl accident is 0.45 (Livingston and

Povinec, 2002). The enhanced activity ratios of 238Pu/239,240Pu

(from 1 to 3) have been measured in environmental samples

derived from industrial nuclear effluents. The highest ratio of238Pu/239,240Pu ¼ 25.3 was reported in October 1982 and was

attributed to discharges from the reprocessing plants at La Hague

and Sellafield (Martin and Thomas, 1988).

In order to check the presence of Pu isotopes in samples

collected after the Fukushima accident between 23 March and 15

April, 2011 (N ¼ 30, sampling air volume ofw2 � 106) all samples

were combined together to form one sample and Pu isotopes were

separated and measured by means of alfa-spectrometry (Fig. 10).

The activity concentration of 239,240Pu in this integrated samplewas

found to be 44.5 � 2.5 nBq/m3, very close to the value measured in

May, 2005 (Fig. 9), and higher than the activity measured in

AprileMay, 2006. The values measured in March, 2006

(12.0 � 0.6 nBq/m3) and May, 2006 (29.2� 1.5 nBq/m3) could serve

therefore as reference data for comparison. From the spectrum

shown in Fig. 10 it can be seen that the activity of 238Pu is higher

than that of 239,240Pu (by a factor of 1.2).

The 238Pu/239,240Pu activity ratios in aerosol samples observed in

May 1986 at Tsukuba, Japan ranged from 0.04 to 0.33. The aero-

dynamic diameter of particles carrying the Chernobyl derived

plutoniumwas estimated to be of 1.1e7 mm and the mean monthly239,240Pu activity concentration increased only by 0.03 mBq m�3

29 1 4 7 10 13 16 25 1 4

1

10

100

1000

10000

1986JuneMayApril

Ac

tiv

ity

co

nc

en

tra

tio

n, m

Bq

/m3

131I

137Cs

103Ru

Fig. 7. Activity concentrations of 131I, 137Cs, 103Ru in aerosol samples in Vilnius in 1986.

G. Lujanien _e et al. / Journal of Environmental Radioactivity 114 (2012) 71e80 77

Fig. 8. An example of 72 h air mass backward trajectories ended at Vilnius sampling site at 19 UTC at 20, 500, 1000 m AGL on 29 January, 1997, on 06 June, 1999 and on 03 February,

2001 for 4 analyzed sectors (modified after De Cort et al., 1998).

5 6 7 8 9 10 11 12 1 2 3 4 5 6 7

0

10

20

30

40

50 239,240Pu

241Am

2005-2006

239

,240P

u,

241A

m, n

Bq

/m3

0

1

2

3

4

137C

s, µ

Bq

/m3

137Cs

Fig. 9. Activity concentrations of 239,240Pu and 241Am in monthly aerosol samples and

monthly average activity concentrations of 137Cs in 2005e2006 in Vilnius.

Fig. 10. Alfa-spectrum of Pu isotopes separated from aerosol samples collected

between 23 March and 15 April.

G. Lujanien _e et al. / Journal of Environmental Radioactivity 114 (2012) 71e8078

(Hirose and Sugimura, 1990). This is approximately the same level

as observed in the aerosol samples collected in Vilnius.

The activity ratio of 238Pu/239,240Pu detected at the Fukushima

site was reported to be 2 (TEPCO, 2011). Assuming the background

ratio equal to the global fallout determined on the basis of the long-

term measurements at the Vilnius site (Lujanien _e et al., 2009) we

can estimate the contribution of the Fukushima plutonium by

simple calculations (Hirose and Sugimura, 1990) using the

following equation:

Fð%Þ ¼ 100$ðRM � RGÞ=ðRF � RGÞ

where F is the Fukushima originated 239,240Pu fraction, RM, RG and RFare the measured, global fallout and Fukushima derived ratios of238Pu/239,240Pu, respectively. According to these estimations the

contribution of the Fukushima derived 239,240Pu is 59% or 26.4

nBq/m3.

The mean activity concentration of 137Cs found in Vilnius

during the studied period was 118 mBq/m3. The background 137Cs

activity concentration can be estimated from the sample collected

one week before the accident and it was 0.7 � 0.1 mBq/m3. From

these estimations the mean Fukushima originated 239,240Pu/137Cs

ratio could be 2$10�4. The activity ratio of 239,240Pu/137Cs in the

Chernobyl originated hot particles was 2$10�2. A fractionation

during the long-distance transport may have resulted in the

variation of the ratio at different locations (Pöllänen et al., 1997;

Hirose and Sugimura, 1990). Further analyses (ICPMS and AMS)

are in progress, which will help to explain Pu origin in this

sample.

4. Conclusions

From the presented data on variations of activity concentrations

of studied radionuclides, from the analyses of meteorological

situation, and on the basis of the modelling exercises we can

conclude that the complicated air mass transport, different arrival

time, arrival height and downward air mass transport resulted in

two maxima of 131I and 137Cs activity concentrations in the near-

surface atmosphere. An increase in the 131I and 137Cs activity

concentrations up to 3800 mBq/m3 and up to 1070 mBq/m3 was

observed on 28 March e 1 April and up to 500 mBq/m3 and up to

1000 mBq/m3 was found on 3e4 April, respectively. In addition to131I and 137Cs, traces of other radionuclides were detected, and 132I,132Te, 129Te, 129mTe and 136Cs among them. The comparison of the

Chernobyl and Fukushima accidents indicated the higher activity

concentration of radionuclides by 4 orders of magnitude and

a broader spectrum of radionuclides in the Chernobyl plume as

compared to the Fukushima one. Large collected air volumes

allowed us to determine for the first time in Europe the activity

ratio and concentration of Fukushima derived 238Pu and 239,240Pu

isotopes. Approximately twice higher Pu activity concentration as

expected, and 238Pu/239,240Pu ratio not typical either for global

fallout or the Chernobyl accident was found in the integrated

aerosol sample.

Acknowledgements

This research was partially supported by the Structural Funds of

EU - the Research and Development Operational Program funded

by the ERDF (project No. 26240220004). The authors thank

students of the Chemical Department of the Vilnius University for

technical assistance. The authors gratefully acknowledge the

NOAA Air Resources Laboratory (ARL) for the provision of the

READY website (http://www.arl.noaa.gov/ready.php) used in this

publication.

References

Abe, T., Kosako, T., Komura, K., 2010. Relationship between variations of 7Be, 210Pband 212Pb concentrations and sub-regional atmospheric transport: simulta-neous observation at distant locations. J. Environ. Radioact. 101, 113e121.

Bolsunovsky, A., Dementyev, D., 2011. Evidence of the radioactive fallout in thecenter of Asia (Russia) following the Fukushima nuclear accident. J. Environ.Radioact. 102 (11), 1062e1064.

Chino, M., Nakayama, H., Nagai, H., Terada, H., Katata, G., Yamazawa, H., 2011.Preliminary estimation of release amounts of 131I and 137Cs accidentally dis-charged from the Fukushima Daiichi nuclear power plant into the atmosphere.J. Nucl. Sci. Technol. 48, 1129e1134.

De Cort, M., Dubois, G., Fridman, Sh.D., Germenchuk, M.G., Izrael, Yu.A., Janssens, A.,Jones, A.R., Kelly, G.N., Kvasnikova, E.V., Matveenko, I.I., Nazarov, I.M.,Pokumeiko, Yu.M., Sitak, V.A., Stukin, E.D., Tabachny, L.Ya., Taturov, S.Yu.,Avdyushin, S.I., 1998. Atlas of Caesium Deposition on Europe after the Cher-nobyl Accident European Commission report EUR16737, Luxembourg.

Diaz Leon, J., Jaffe, D.A., Kaspar, J., Knecht, A., Miller, M.L., Robertson, R.G.H.,Schubert, A.G., 2011. Arrival time and magnitude of airborne fission productsfrom the Fukushima, Japan, reactor incident as measured in Seattle, WA, USA.J. Environ. Radioact. 102, 1032e1038.

Draxler, R.R., Rolph, G.D., 2011. HYSPLIT (Hybrid Single-particle Lagrangian Inte-grated Trajectoy). NOAA Air Resources Laboratory, Silver Spring, MD, USA.http://ready.arl.noaa.gov/HYSPLIT.php.

Fushimi, K., Nakayama, S., Sakama, M., Sakaguchi, Y., 2011. Measurement of airborneradioactivity from the Fukushima reactor accident in Tokushima, Japan. J. Phys.Soc. Jpn. arXiv:1104.3611v2.

Hirose, K., Sugimura, Y., 1990. Plutonium isotopes in the surface air in Japan: effectof chernobyl accident. J. Radioanal. Nucl. Chem. Articles 138, 127e138.

Hu, Q.-H., Weng, J.-Q., Wang, J.-S., 2010. Sources of anthropogenic radionuclides inthe environment: a review. J. Envirom. Radioact. 101, 426e437.

IAEA, 2006. Environmental Consequences of the Chernobyl Accident and TheirRemediation: Twenty Years of Experience. RARS, Vienna.

IAEA, 2011. Briefing on Fukushima Nuclear Accident. www.iaea.org/newscenter/news/tsunamiupdate01.html/ 12 April 2011.

Jordan, C.E., Dibb, J.E., Finkel, R.E., 2003. 10Be/7Be tracer of atmospheric transportand stratosphere-troposphere exchange. J. Geophys. Res. 108, 4234e4247.

Koch, D.M., Jacob, D.J., Graustein, W.C., 1996. Vertical transport of troposphericaerosols as indicated by 7Be and 210Pb in a chemical tracer model. J. Geophys.Res. 101, 18,651e18,666.

Kownacka, L., 2002. Vertical distributions of beryllium-7 and lead-210 in thetropospheric and lower stratospheric air. Nukleonika 47, 79e82.

Land, C., Feichter, J., 2003. Stratosphereetroposphere exchange in a changingclimate simulated with the general circulation model MAECHAM4. J. Geophys.Res. 108, 8523e8532.

Livingston, H.D., Povinec, P.P., 2002. Millennium perspective on the contribution ofglobal fallout radionuclides to ocean science. Health Phys. 82, 656e668.

Lozano, R.L., Hernández-Ceballos, M.A., Adame, J.A., Casas-Ruíz, M., Sorribas, M., SanMiguel, E.G., Bolívar, J.P., 2011. Radioactive impact of Fukushima accident on theIberian Peninsula: evolution and plume previous pathway. Environ. Int. 37,1259e1264.

Lujanas, V., Lujanien _e, G., 2007. Application of cosmogenic radionuclides in ozonetracer studies. J. Radioanal. Nucl. Chem. 274, 287e291.

Lujanas, V., Mastauskas, A., Lujaniene, G., Spirkauskaite, N., 1994. Development ofradiation in Lithuania. J. Environ. Radioact. 23, 249e263.

Lujanien _e, G., Aninkevi�cius, V., Lujanas, V., 2009. Artificial radionuclides in theatmosphere over Lithuania. J. Environ. Radioact. 100, 108e119.

Lujanien _e, G., �Sapolaite, J., Remeikis, V., Lujanas, V., Jermolajev, A., Aninkevi�cius, V.,2006. Cesium, americium and plutonium isotopes in ground level air of Vilnius.Czech. J. Physiol. 56 (Suppl. 4), D55eD61.

Lujanien _e, G., Lujanas, V., Mastauskas, A., Ladygien _e, R., Ogorodnikov, B.L.,Stelingis, K., 1998. Influence of physico-chemical forms of radionuclides on theirmigration in the environment. Radiochim. Acta 82 (1), 305e310.

Lujanien _e, G., 2000. Investigation of cosmogenic radionuclide carriers in theatmosphere. Czech. J. Phys. 50, 321e329.

Lujanien _e, G., 2003. Study of removal processes of 7Be and 137Cs from the atmo-sphere. Czech. J. Phys. 53, A57eA65.

Lujanien _e, G., Lujanas, V., Jank�unait _e, D., Ogorodnikov, B.I., Mastauskas, A.,Ladygien _e, R., 1999. Speciation of radionuclides of the chernobyl origin inaerosol and soil samples. Czech. J. Phys. 49 (1), 107e112.

Lujanien _e, G., By�cenkien _e, S., �S�ciglo, T., Povinec, P.P., Gera, M., Bartok, J., Ga�zák, M.,2011. Radionuclides from the Fukushima Accident in Europe e Modelling theAir Mass Transport. In: Proceedings FSKD 2011, vol. 4, 26-28 July, 2011,Shanghai, China, pp. 2775e2777.

Lujanien _e, G., Ogorodnikov, B., Budyka, A., Skitovich, V., Lujanas, V., 1997.An investigation of changes in radionuclide carrier properties. Adv. Space. Res.35, 71e90.

Manolopoulou, M., Vagena, E., Stoulos, S., Ioannidou, A., Papastefanou, C., 2011.Radioiodine and radiocesium in Thessaloniki, Northern Greece due to theFukushima nuclear accident. J. Environ. Radioact. 102, 796e797.

Martin, J.M., Thomas, A.J., 1988. Anomalous concentrations of atmosphericplutonium-238 over Paris. J. Environ. Radioact. 7, 1e16.

Masson, O., Baeza, A., Bieringer, J., Brudecki, K., Bucci, S., Cappai, M., Carvalho, F.P.,Connan, O., Cosma, C., Dalheimer, A., Didier, D., Depuydt, G., De Geer, L.E., De

G. Lujanien _e et al. / Journal of Environmental Radioactivity 114 (2012) 71e80 79

Vismes, A., Gini, L., Groppi, F., Gudnason, K., Gurriaran, R., Hainz, D.,Halldorsson, O., Hammond, D., Hanley, O., Holey, K., Homoki, Zs., Ioannidou, A.,Isajenko, K., Jankovick, M., Katzlberger, C., Kettunen, M., Kierepko, R., Kontro, R.,Kwakman, P.J.M., Lecomte, M., Leon Vintro, L., Leppänen, A.-P., Lind, B.,Lujanien _e, G., Mc Ginnity, P., Mc Mahon, C., Mala, H., Manenti, S.,Manolopoulou, M., Mattila, A., Mauring, A., Mietelski, J.W., Møller, B.S.,Nielsen, P., Nikolick, J., Overwater, R.M.W., Palsson, S.E., Papastefanou, C.,Penev, I., Pham, M.K., Povinec, P.P., Ramebäck, H., Reis, M.C., Ringer, W.,Rodriguez, A., Rulík, P., Saey, P.R.J., Samsonov, V., Schlosser, C., Sgorbati, G.,Silobritiene, B.V., Söderström, C., Sogni, R., Solier, L., Sonck, M., Steinhauser, G.,Steinkopff, T., Steinmann, P., Stoulos, S., Sykora, I., Todorovic, D., Tooloutalaie, N.,Tositti, L., Tschiersch, J., Ugron, A., Vagena, E., Vargas, A., Wershofen, A.H.,Zhukova, O., 2011. Tracking of airborne radionuclides from the damagedFukushima Dai-ichi nuclear reactors by European Networks. Environ. Sci.Technol. 45, 7670e7677.

Microstep, 2011. http://www.microstep-mis.com/index.php?lang¼en&site¼src/products/radiation_monitoring/ims_model_suite, 23.5.2011 [online].

NISA, 2011. http://www.nisa.meti.go.jp/.Papastefanou, C., 2009. Radon decay product aerosols in ambient air aerosol and air.

Qual. Res. 9, 385e393.Pittauerová, D., Hettwig, B., Fischer, H.W., 2011. Fukushima fallout in Northwest

German environmental media. J. Environ. Radioact. 102, 877e880.Pöllänen, R., Valkama, I., Toivonen, H., 1997. Transport of radioactive particles from

the chernobyl accident. Atmos. Environ. 31 (21), 3575e3590.

Rolph, G.D., 2011. Real-time Environmental Applications and Display SYstem(READY). NOAA Air Resources Laboratory, Silver Spring, MD. Website. http://ready.arl.noaa.gov.

Sheets, R.W., Lawrence, A.E., 1999. Comparative temporal behavior of radon- andthoron-progeny in surface air over the midwestern U.S. J. Radioanal. Nucl.Chem. 242, 761e767.

TEPCO, 2011. Detection of Radioactive Material in the Soil in Fukushima DaiichiNuclear Power Station. http://www.tepco.co.jp/en/press/corp-com/release/11032812-e.html.

Winiarek, V., Bocquet, M., Roustan, Y., Birman, C., Tran, P., 2011. AtmosphericDispersion of Radionuclides from the Fukushima-Daichii Nuclear Power Plant.http://cerea.enpc.fr/fr/fukushima.html.

WMO, 2009. World meteorological organization: manual on Codes. InternationalCodes. In: Part B e Binary Codes. Part C e Common Features to Binary andAlphanumeric Codes. WMO-No. 306, vol. I.2. Secretariat of the World Meteo-rological Organization, Geneva. pp.740.

Wotawa, G., 2011. Accident in the Japanese NPP Fukushima: Synthesis of OurCurrent Calculations and CTBTO Data Shows Global Spread of Air MassesOriginating from Japan (Update: 25 March 201116:00). http://www.zamg.ac.at/docs/aktuell/Japan2011-03-25_1600_E_2.pdf.

Yoshimori, M., 2005. Beryllium 7 radionucleide as a tracer of vertical air masstransport in the troposphere. Adv. Space Res. 36, 828e832.

Závodský, D. (Ed.), 2011. Atmospheric Chemistry and Air Pollution Modelling.Leonardo da Vinci Programme. Matej Bel University, Banská Bystrica, pp. 127.

G. Lujanien _e et al. / Journal of Environmental Radioactivity 114 (2012) 71e8080