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Ecological Indicators 25 (2013) 197–199

Contents lists available at SciVerse ScienceDirect

Ecological Indicators

jo ur nal homep age: www.elsev ier .com/ locate /eco l ind

adioecological indexes of fallout measurementsrom the Fukushima nuclear accident

. Manolopoulou, S. Stoulos, A. Ioannidou, E. Vagena, C. Papastefanou ∗

ristotle University of Thessaloniki, Atomic and Nuclear Physics Laboratory, Thessaloniki 54124, Greece

r t i c l e i n f o

rticle history:eceived 12 August 2011eceived in revised form8 September 2012ccepted 22 September 2012

a b s t r a c t

Fallout from the Fukushima nuclear accident has been monitored for about 1 month in Thessaloniki,Northern Greece. Three different radionuclides, one short-lived, one relatively long-lived and one long-lived fission product were identified in air, grass and milk samples. The 131I, 137Cs and 134Cs activityconcentrations in air reached 497, 145 and 126 �Bq m−3, respectively on 4 April, 2011. These radionu-clides are of particular concern regarding their transfer from the environment to population through

eywords:31I37Cs34Csalloutco-indexesukushima nuclear accident

the ingestion pathways for the assessment of the Fukushima accident consequences. Radioecologicalindexes (eco-indexes) of fallout measurements in the air–grass–cow-milk–man pathway for 131I weredetermined, as they are related to radiological impact of the Fukushima derived radionuclides on thepublic and environment.

© 2012 Elsevier Ltd. All rights reserved.

. Introduction

On 11 March 2011, at around 08:15 CET Japan experienced aajor earthquake of ML = 9.0 magnitude followed by a tsunami

f catastrophic magnitude which caused a serious nuclear acci-ent occurred at the Fukushima Daiichi nuclear power plant37◦25′17′′N, 141◦1′57′′E), about 250 km north to Tokyo, capital ofapan. According to the IAEA update report of 17 March 01:15 UTCIAEA, 2011) problems on the cooling systems of the Fukushimaaiichi 1 of 439 MWe in power, Fukushima Daiichi 2 of 760 MWend Fukushima Daiichi 3 of 760 MWe, all boiling water reactors,WR were shut down automatically and no radiation release hadeen detected there.

On 26 March 2011, high values of radioactive deposition ofssion product radionuclides were occurred in the prefecture ofamagata, Japan, as high as 7500 Bq m−2 for 131I and 1200 Bq m−2

or 137Cs (IAEA, 2011). Two days later, on 28 March 2011, highalues of radioactive deposition of the above radionuclides wereccurred in the prefecture of Fukushima as high as 23,000 Bq m−2

or 131I and 790 Bq m−2 for 137Cs (IAEA, 2011).

According to the Rhenish Institute for Environmental Research

t the University of Cologne, Germany, a cloud containing radioac-ivity was formed in air over the Fukushima nuclear power plant,

∗ Corresponding author. Tel.: +30 2310 998005; fax: +30 2310 998058.E-mail address: papastefanou@physics.auth.gr (C. Papastefanou).

470-160X/$ – see front matter © 2012 Elsevier Ltd. All rights reserved.ttp://dx.doi.org/10.1016/j.ecolind.2012.09.016

NPP and moved over the Pacific Ocean, north from Japan in thedirection to the Arctic Ocean. Therefore, that radioactive cloudentered to the Atlantic Ocean over Iceland and then diffused overthe European continent (Jakobs, 2011). The transferred radioactiv-ity by that cloud caused detectable radioactive contamination inair over Thessaloniki, Northern Greece from 24 March 2011, to 25April 2011 and in more than 25 countries over Europe. Many inves-tigators have subsequently presented their initial observations andpreliminary results on the fallout from the Fukushima nuclear acci-dent, particularly in European countries (Masson et al., in press)and in USA as well (Bowyer et al., 2011) and early estimates of theradiological consequences have been done.

This paper reports on a series of measurements of the fissionproduct radionuclides present in air, grass and milk samples inThessaloniki, Northern Greece in order to determine some spe-cial radioecological indexes of fallout measurements from theFukushima nuclear accident. Although the measurements hererefer to the region of Thessaloniki, the concluding remarks shouldbe considered to be more general.

2. Experimental procedures

After the announcement of the Fukushima nuclear accident, the

Atomic and Nuclear Physics Laboratory of the Aristotle University ofThessaloniki at Thessaloniki, Northern Greece (40◦38′N, 22◦58′E)initiated measurements on fallout of the radioactive debristransported from Fukushima, Japan (37◦25′17′′N, 141◦1′57′′E).

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ontinuous monitoring had been carried out there for more than5 years, producing a clear picture of background radiation levelsrior to the accident.

Air sampling was carried out using a Staplex type TFIA-2 higholume air sampler operating with a glass fiber filter type TFAGF10 with dimensions 8 in. × 10 in. and the collection efficiency was5% of particles 0.5 �m and over. This design involves a regulatedir flow rate ranging from 28 to 31 L s−1. The length of collectioneriod was about 24 h. The sample quantity was about 2800 m3 ofir. This monitoring system set up is a routine system.

Grass samples was cut from an area of 3 m2 (0.125 kg grass per2) for each sample at the same time in the university campus of

he Aristotle University of Thessaloniki, at Thessaloniki, Northernreece.

Milk samples were also collected from cows at the same periodn the nearest area of the city of Thessaloniki. The activity ofach milk sample of 1 L volume was measured in a Marinellieaker.

All the samples were measured for radioactivity using a highurity and low background Ge detector of high resolution (1.9 keVt 1.33 MeV) and high efficiency (42%). The activity concentra-ions of radionuclides were measured for 131I using the 0.364 MeVamma-ray photons, for 137Cs using the 0.662 MeV gamma-rayhotons and for 134Cs using the 0.605 MeV gamma-ray photons. The-spectroscopic system was calibrated using standard referenceources in all case, the overall efficiency being known to accura-ies of better than 5% for the filter geometry and about 12% for thearinelli system.

. Measurement results

.1. Air

Air sampling for the Fukushima debris commenced on March 24nd continued until April 25 and onwards. Sampling was performedvery 2 days. The results of the activity concentrations of aerosol-ound radionuclides in air from March 24, 2011 through April 25,011 due to the nuclear accident at Fukushima, Japan, are presented

n Table 1. It is noted that radioiodine and radiocesium isotopesere not present in air in Thessaloniki, Greece before March 24,

011.The activity concentration of 131I in particulate form in air

43 �Bq m−3 was first observed on March 24, 2011, while gaseousodine concentrations were not measured. Two days later, on March

able 1articulate 131I and 137+134Cs, in �Bq m−3, in air at Thessaloniki, Northern Greece for the p

Date 131I 137Cs

24–25 March 143 ± 21 <11a

26–27 March 332 ± 28 18 ± 4

28–29 March 150 ± 19 7.5 ± 1.2

29–30 March 160 ± 20 7.5 ± 1.2

31 March–01 April 296 ± 36 19 ± 6

01–02 April 340 ± 36 23 ± 7

02–03 April 324 ± 34 39 ± 5

04–05 April 497 ± 53 145 ± 18

05–06 April 324 ± 35 85 ± 11

06–07 April 196 ± 25 33 ± 5

08–09 April 304 ± 32 37 ± 6

10 April 425 ± 48 27 ± 9

13–14 April 71 ± 10 27 ± 5

14–15 April 58 ± 8 <5a

16–17 April 63 ± 8 <6a

18–19 April 64 ± 8 11 ± 3

20–21 April 58 ± 8 14 ± 4

22–23 April 32 ± 5 9 ± 3

24–25 April 15 ± 4 <6a

a MDA, minimum detectable activity.

ndicators 25 (2013) 197–199

26, 2011, 131I in air peaked to 332 �Bq m−3. Gaseous iodine con-centrations were several times higher at least in several places inEurope from where results were reported (Masson et al., in press).Cesium-137 was first observed in air on March 26, 2011 and itsactivity concentration was 18 �Bq m−3, whereas that of 134Cs was12 �Bq m−3, giving a ratio of 137Cs/134Cs = 1.5. According to themeasurements of KEK High Energy Accelerator Research Organi-zation at Tsukuba, Japan, the ratio 137Cs/134Cs was equal to 0.97,almost 1.0, at the period 15 March, 2011 14:39–15 March, 201117:34 h local time (KEK, 2011). The ratio of 137Cs/134Cs (Table 1)in air in Thessaloniki was first 1.5 on March 26, 2011 and thendeclined to almost 1.0 as was expected and observed in Fukushima,Japan when escaped from nuclear reactors (KEK, 2011). The higherratio of 137Cs/134Cs in Thessaloniki probably results from dilutionof 134Cs from Fukushima with older 137Cs from local resuspension.It is noteworthy that Bowyer et al. (2011) measured 133Xe in air,a short-lived (5.2 days) product of nuclear fission, on March 16,2011 at the Pacific Northwest National Laboratory (PNNL) at Rich-land, Washington (46◦16′47′′N, 119◦16′53′′W) located more than7000 km from the emission point in Fukushima, Japan (37◦25′17′′N,141◦1′57′′E).

In Athens (37◦59′N, 23◦33′E), the capital of Greece, in CentralGreece, the highest concentration of particulate 131I in air wasobserved on March 26, 2011 250 �Bq m−3 in Aghia Paraskevi area(GAEC, 2011) and much higher 347 �Bq m−3 on March 31, 2011 inZografou area (NTUA, 2011).

The first peak of 131I between 24 and 28 March 2011 shows the131I that first escaped from the Fukushima nuclear power plant. Thepresence of more than one peak of 131I and 137+134Cs indicates that131I and 137+134Cs were continuously transferred from Fukushima,Japan to Greece till April 25, 2011, at least. Beside this, a sharp peakof 0.65 �Sv h−1 was observed on March 16, 2011, in the dose rateat Tsukumba, Japan, in the KEK High Energy Accelerator ResearchOrganization, then dropped to 0.2 �Sv h−1 on March 17, 2011 andremained almost stable to at least 01 April 2011 (KEK, 2011).

The ratio of 131I/137Cs (Table 1) in air in Thessaloniki was first18.4 on March 26, 2011 depended on the short half life of 131I andthen decreased to 3.4 on April 04, 2011. Beside this, the radioactivecloud was first richer in 131I, as iodine is a more volatile elementthan cesium. That change was repeated again from April 10, 2011

to April 23, 2011.

131I and 137+134Cs as well were not detected in air after April 27,2011 and till May 26, 2011. The detectable limit of 131I was then4 �Bq m−3 and of 137Cs was 5 �Bq m−3.

eriod 24 March 2011–25 April 2011.

134Cs 131I/137Cs 137Cs/134Cs

<9a

12 ± 3 18.4 1.55 ± 15 ± 111 ± 5 15.6 1.715 ± 3 14.8 1.540 ± 4 8.3 1.0126 ± 11 3.4 1.283 ± 9 3.8 1.036 ± 4 5.9 0.932 ± 4 8.2 1.218 ± 7 15.7 1.524 ± 8 2.6 1.1<5a

<6a

8 ± 3 5.8 1.410 ± 3 4.1 1.47 ± 2 3.6 1.3<6a

M. Manolopoulou et al. / Ecological Indicators 25 (2013) 197–199 199

Table 2Activity concentrations of fission product radionuclides in grass samples (Bq kg−1).

Date of sampling 131I 137Cs 134Cs

Soil Grass Soil Grass Soil Grass

7 April 2011 ND 0.84 ± 0.13b 46 ± 5.2 0.38 ± 0.05b ND <0.07a,b

1.31 ± 0.17c 0.33 ± 0.11c NDc

ND, not detected.a MDA, minimum detectable activity.b Wet grass.c Air dried grass.

Table 3Activity concentrations of fission product radionuclides in cow’s milk (Bq L−1).

Date of sampling 131I 137Cs 134Cs

3

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hc

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a

B

wCi

Cd

30 March 2011 1.20 ± 0.13 0.092 ± 0.026 <0.047 April 2011 0.35 ± 0.05 0.15 ± 0.03 <0.04

.2. Grass

The dry and wet deposition of fission product radionuclides onhe ground is responsible for the contamination of grass. Rainfallvents had occurred on 28–29 Mach 2011 with height of precipi-ation 180 mm. The results of the activity concentrations of fissionroduct radionuclides in grass are summarized in Table 2. Iodine-31 was detected in grass in the level of a becquerel per kg. Cesium37 + 134 were also detected and measured in the grass samples.

.3. Milk

Iodine-131 was also detected and measured in the cow’s milkroduced and collected on March 30, 2011, with a level of 1.2 Bq L−1

nd dropped to 0.35 Bq L−1, on April 7, 2011, that is four timesower (Table 3). Cesium-137 in milk is probably from Chernobylnd global fallout since no 134Cs was found.

. Radioecological indexes

The fission product radionuclides passed into the food chainy foliar deposition with subsequent metabolic incorporation intolants, e.g. by foliar absorption, so that they were transferred intoontaminated food products, especially milk, which indeed is theost important indicator of such transfer.In the air–grass–cow-milk–man pathway for 131I, in which the

uman thyroid dose is affected by ingestion, the following ratiosan readily be derived:

= Cg

Ca, m3 kg−1

nd

= Cm

Cg, kg L−1

here Ca is the radionuclide activity concentration in air, Bq m−3,g the radionuclide activity concentration in grass, Bq kg−1, and Cm

s the radionuclide activity concentration in cow’s milk, Bq L−1.From the data of Tables 1–3, taking into account

a = 196 �Bq m−3, Cg = 0.84 Bq kg−1 and Cm = 0.3 Bq L−1 for theate of 07 April 2011 in the mid time period of measurements,

values of A and B ratios as high as 4286 m3 kg−1 and 0.36 kg L−1,respectively, were obtained. These ratios are considered as eco-indexes, that is radioecological indexes for a nuclear accidentregarding the consequences to humans from routine releases ofreactor effluents. In the case of the Chernobyl reactor accident,Papastefanou et al. (1988) following environmental measurementsat Thessaloniki, Greece, estimated the values of A and B ratiosas equal to 4233 m3 kg−1 and 0.15 kg L−1, respectively. In theliterature, Soldat (1963), as cited in Eisenbud (1973), based onstudies at Hanford Laboratories, in Richland, WA, which is amongthe largest atomic plants in the USA, found that over a 2-yeargrowing season for the Hanford workers, the corresponding valuesfor A and B ratios were as high as 4200 m3 kg−1 and 0.15 kg L−1,respectively.

5. Conclusions

The eco-indexes were determined from the fallout mea-surements from the Fukushima nuclear accident as follows:A = Cg/Ca = 4286 m3 kg−1 and B = Cm/Cg = 0.36 kg L−1, where Ca is theradionuclide activity concentration in air, Cg is the radionuclideactivity concentration in grass, and Cm is the radionuclide activ-ity concentration in cow’s milk. The obtained results are in awell agreement as in the case of the Chernobyl accident before25 years, with the corresponding values of A = 4233 m3 kg−1 andB = 0.15 kg L−1.

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