Monitoring of Aerosol and Fallout Radioactivity in BelgradeAfter the Fukushima Reactors Accident

Jelena Nikolic & Gordana Pantelic &

Dragana Todorovic & Marija Jankovic &

Maja Eremić Savkovic

Received: 29 November 2011 /Accepted: 12 June 2012 /Published online: 4 July 2012# Springer Science+Business Media B.V. 2012

Abstract After the accident in Fukushima reactors,a daily monitoring programme was initiated in twolaboratories in Belgrade, one at the Vinčа Institutefor Nuclear Sciences and the other at Institute forOccupational Health Karajovic. Samples of aerosoland fallout, as well as the random samples of foodand water, were collected and analysed, usinggross alpha/beta and gamma spectrometry, in orderto establish the presence of traces of isotopesindicating Fukushima fallout. Gamma spectrometrymeasurement of these samples showed clear evi-dence of fission products 131I, 134Cs and 137Cswtihin 2 weeks after the accident. The activity dimin-ished with time due to dispersion in air and, incase of 131I, short half-life.

Keywords 131I . 134Cs . 137Cs . Aerosols . Fallout

1 Introduction

The Fukushima Daiici nuclear power plant accidentcaused a large regional release of radionuclides intothe atmosphere and subsequent radioactive contami-nation of the environment. Once released into theatmosphere, long-range atmospheric transport pro-cesses can cause a widespread distribution of radioac-tive matter. The fallout consisting of short-lived andlong-lived radionuclides eventually affects humanseither directly or indirectly by entering the food chainthrough plants and animals.

The radioactive contamination originating fromFukushima was detected not only in Japan and Asia,but also in the entire northern hemisphere, includingUSA and Europe (Chino et al. 2011; Diaz Leon et al.2011; Manolopoulou et al. 2011; Pittauerová et al. 2011;Wakeford 2011). The fallout spread from Fukushimaacross the Pacific ocean and American continent, thenover the Atlantic ocean, and finally came to Europe,where it was first detected in Iceland and Scandinavia.After that, all European countries reported detection ofthe elements originating from Fukushima reactors.

Serbia has developed a monitoring programme60 years ago. The contents of radionuclides are deter-mined in aerosol, soil, fallout (wet and dry deposition),rivers, lake and drinking water, human and animal food,on monthly basis. This network and monitoring pro-grammes were updated after the Chernobyl accident.

Water Air Soil Pollut (2012) 223:4823–4829DOI 10.1007/s11270-012-1238-x

J. Nikolic (*) :G. Pantelic :D. Todorovic :M. JankovicUniversity of Belgrade Vinča Institute of Nuclear Sciences,Mike Petrovića Alasa 12-14,11001 Belgrade, Serbiae-mail: jnikolic@vinca.rs

M. E. SavkovicSerbian Institute of Occupational Health“Dr Dragomir Karajović”,Deligradska 29,11000 Belgrade, Serbia

As a first response to the Fukushima accident, five aircollection stations and three fallout collection stations,situated in and around the Vinča Institute of NuclearSciences in Belgrade, were used for daily sample col-lection (Popović 2007). Also, the Institute for Ocupa-tional Health Karajovic analysed samples taken fromone air station situated in the centre of Belgrade andtwo fallout sampling sites in the nearby counties ofLazarevac and Obrenovac, producing a total of six airand five fallout sampling stations at the teritory ofBelgrade city region. Radionuclide content in aerosoland fallout was determined both in daily and compositemonthly samples. The coordinates and type of samplersare given in Table 1 (samples from the locations namedVinča 1, Vinča 2, Vinča 3, Vinča 4 and Belgrade 2 wereanalysed in the Vinca Institute of Nuclear Sciences, andsamples from locations Belgrade 1, Lazarevac andObrenovac were analysed in the Institute for Ocupa-tional Health Karajovic). A more detailed plan of mon-itoring is already in motion, and will include samplecollection from numerous stations distributed in otherparts of the country.

After a nuclear accident, contamination of food andland can occur either from deposition of material origi-nally introduced to atmosphere or through the foodchain. Because of that, random food and soil sampleswere analysed to confirm eventual presence of contam-ination. The food samples included green vegetables(spinach, greens and salad), cow and goat milk, grassand clover for cattle feed. The soil samples were col-lected at the Danube and Danube confluents’ coasts.

It was expected that some traces of isotopes re-leased from Fukushima accident should be detectedin the last week of March, according to previousinvestigations of release from nuclear weapons testsconducted in China in the mid-sixties of the twentieth

century (Todorovic 2000). The results presented in thispaper represent the investigation of daily measurementsof aerosol filters from six stations, fallout and compositesamples from five stations and random food and soilsamples obtained in the above-mentioned institutes.

2 Materials and Methods

Air samples were collected daily, 1 m above groundby airflow pump, pumping the air trough the filterpaper. At five locations (Table 1), F&J Digital HighVolume Environmental Air Sampling System DH-60810 Ev.2 was used and aerosol samples were col-lected using Whatman 41/No.5A, 20×25-cm filterpapers, with relative efficiency of 81 % for depositeddust. The samplers have constant flow rate, of average30–50 m3/h. The Petrianov FPP-15-1.5 type filter 40×40 cm with relative efficiency of 96 to 99 % was usedat one high volume ASS-500 station with average flowrate of 500 m3/h at the location Belgrade 2. The filterswere replaced every day at 8 a.m., covering a totalperiod from March 18 to April 30, 2011. Samples offallout (dry and wet precipitation) were collected inthe container 1 m above of uncultivated soil at loca-tions in the centre of Belgrade, the vicinity of VinčaInstitute, Lazrevac and Obrenovac.

The air filter samples collected at five stations(Vinča1, Vinča 2, Vinča 3, Vinča 4 and Belgrade 2)were cut in the form that corresponds to the measure-ment geometry and measured, without ashing, 5 h and5 days after sampling, on lowbackground alpha/betaproportonal counter Thermo Eberline FHT770T. Thecorrection factor for the cut surface/total surface of thefilter paper was calculated, so that the final resultrepresented the whole sample. The first measurement

Table 1 The coordinates ofsampling sites, type of aerosolsampler, fallout containerarea and sampling frequencyfor the sampling stations

Station Coordinates Aerosol sampler Falloutcontainer (m2)

Frequency ofsampling

Vinča 1 44°45′ N, 20°35′ E F&J System 0.16 Daily

Vinča 2 44°45′ N, 20°36′ E F&J System – Daily

Vinča 3 44°46′ N, 20°37′ E F&J System – Daily

Vinča 4 44°44′ N, 20°36′ E F&J System – Daily

Belgrade 1 44°48′ N, 20°28′ E ASS-500 station 0.1 Daily

Belgrade 2 44°47′ N, 20°25′ E F&J System 1 Daily

Lazarevac 44°23′ N, 20°16′ E – 0.1 Monthly

Obrenovac 44°39′ N, 20°12′ E – 0.1 Monthly

4824 Water Air Soil Pollut (2012) 223:4823–4829

produced the data on the total short- and long-livedradionuclides in air, and the second one produced thedata on the activity of long-lived radionuclides only.After the gross alpha and beta measurement at the day ofthe collection, these five daily filters were combined toform one composite sample and placed, without ashing,into a plastic container. Composite daily sample wasmeasured by gamma spectrometry using HP Ge detec-tion systems Canberra, relative efficiency 23 %, resolu-tion 1.89 keV at 1,332 keV. At the end of the month,samples from each aerosol station were combined toformmothly sample (i.e. 30 air samples from one stationwere combined in one composite monthly sample at thatstation) for gamma spectrometry measurement.

The air samples collected at the location Belgrade 1were measured, without ashing, using ultra-low back-groundHPGe detection systems Ortec-Ametek, relativeefficiency 40 % and resolution 1.85 keV at 1,332 keV.Fallout smples were collected using a plastic foil cover-ing the fallout container. After collection of the dailysample, the foil was placed into a plastic container andmeasured immediately without any other preparation inorder to aviod the loss of iodine. If there was any wetprecipitation, the content of the foil was placed into aplastic bottle of 250 ml without evaporation. Compositemonthly sample of the fallout was formed by collectingall daily samples from corresponding locations (exceptthe samples collected at Lazarevac and Obrenovacwhere monthly samples were obtained by exposing thesampler to the precipitation during the whole month)and prepared by mineralization at 450 °C. Daily andmonthly samples collected at the locations Vinča 1 andBelgrade 2 were measured at Vinča Institute of Nuclear

Sciences by HP Ge detection systems Canberra, relativeefficiency 23 %, and samples collected at the locationsBelgrade 1, Lazarevac and Obrenovac were mea-sured at Institute of Occupational Health Karajovicusing ultra-low background HP Ge detection systemsOrtec-Ametek, relative efficiency 40 %.

3 Results and Discussion

The daily measurement of aerosol filters and falloutstarted on March 18, 2011, 6 days after the accident atthe Fukushima Daiici nuclear power plant. The grossalpha and beta activity in aerosol filters measured 5 hafter sampling did not show any increase of activitycompared to measurements before the Fukushima ac-cident (Todorovic et al. 1996). The ratio of gross betaactivity/gross alpha activity in these measurement wasbetween 2 and 2.5 for the entire examination period,except for the filters exposed from March 29 to 30,when this ratio was betwen 2.7 and 3.7 for filterscollected at all stations.

Time variation of gross beta activity concentrationin aerosol samples measured 5 days after sampling atfive aerosol sampling stations measured by VinčaInstitute of Nuclear Sciences is presented on Fig. 1.These measurements also showed the maximum betaactivity on filters exposed from March 29 to March 30.The highest value of 3.6 mBq/m3 was measured ataerosol filter collected at Vinča 3 station. This corre-sponds to the highest detected 131I activity in aerosolfilters which will be shown later in this paper. Thispeak of activity is expected, according to previous

Fig. 1 Time variation ofgross alpha beta activityconcentration in aerosol atlocations Vinča 1, Vinča 2,Vinča 3, Vinča 4 and Bel-grade 2, measured by VinčaInstitute of Nuclear Sciences5 days after sampling; theresults are given at two-sigma level of uncertainty

Water Air Soil Pollut (2012) 223:4823–4829 4825

experience, to occur 15–20 days after the release ofradioactive contaminants, and here, this presumptionis confirmed (Todorovic 2000). The dates on all fig-ures correspond to days when the filters were changedon aerosol pumps.

On March 23, the depostion of 131I was detected onaerosol samples (as it can be seen in Fig. 2) and the firstdetection of 134Cs occured on March 29 (shown inFig. 3). The highest activity observed for 131I in aerosolwas 1.6 mBq/m3 on March 29 and 30. 131I activity inaerosol decreased after April 12. Figures 2 and 3 repre-sent the mean values obtained daily from compositesamples (as described in the Introduction section),where Institut Vinca represents the composite samplesfrom locations Vinča 1, Vinča 2, Vinča 3, Vinča 4 andBelgrade 2 (since those were measured at Vinča Instituteof Nuclear Sciences) and Institut Karajovic represents

the samples from location Belgrade 1. The resultsobtained from the latter show higher values, presumablydue to greater average flow rate at that station.

During the first week of the measurement, only the137Cs activity was measurable, but that was estimatedto be a consequence the Chernobyl accident. Theaverage 137Cs activity in the first week was 1 μBq/m3 which is at the same level as the value obtained in2010. The average 137Cs activity in aerosol in Bel-grade in 2010 was 0.78 μBq/m3 with the maximumvalue 1.8 μBq/m3 in March 2010 (Serbian RadiationProtection and Nuclear Safety Agency 2011).

The maximum value for 134Cs in aerosol was0.14 mBq/m3 on March 29 and 30 and 0.136 mBq/m3

on April 8 and 9. The maximum values for 137Csin aerosol were 0.16 and 0.144 mBq/m3 at thesame days (Fig. 4). According to the measurement

Fig. 2 Time variation of131I activity concentrationin daily aerosol samplesmeasured by Vinča Instituteof Nuclear Sciences (InstitutVinca) and measured by In-stitute for OccupationalHealth Karajovic (InstitutKarajovic), 5 h after sam-pling; the results are given attwo-sigma level ofuncertainty

Fig. 3 Time variation of134Cs activity concentrationin daily aerosol samplesmeasured by Vinča Instituteof Nuclear Sciences (InstitutVinca) and measured by In-stitute for OccupationalHealth Karajovic (InstitutKarajovic), 5 h after sam-pling; the results are given attwo-sigma level ofuncertainty

4826 Water Air Soil Pollut (2012) 223:4823–4829

of KEK (2011), the 137Cs/134Cs ratio was aprox-imately equal to unity. In our measurement, the137Cs/134Cs ratio was equal to 1.1, which showspresence of 137Cs from Chernobyl accident. Themeasurement results over the years showed thatevery winter and spring, there is a certain airexchange between the stratosphere and the tropo-sphere, vertical mixing within the troposphere andthe washout effects, which leads to increasing of 137Csactivity in aerosol (Todorovic 1997; Jankovic andTodorovic 2011).

134Cs and 137Cs were first detected in aerosol sam-ples collected at air sampling station Belgrade 1 (Figs. 3and 4) because the air flow rate at ASS 500 station ismuch higher than on other sampling stations, and hence,the perceptibility is greater. After April 23 the dailydeposition of 134Cs was below minimal detectable

concentration (MDC) which was 8.4 μBq/m3 and137Cs below 6.4 μBq/m3.

Measured concentrations of 134Cs and 137Cs incomposite monthly aerosol samples collected at allstations except Lazarevac and Obrenovac are pre-sented in Table 2, at the uncertainty level of twosigma. The results showed similar activity concentra-tion ratio 137Cs/134Cs as it was in the daily measure-ment. The measured 131I activity was below detectionlimit, due to short half-life of iodine and because themonthly samples represent mineralised daily filters,from which iodine dissapeared as a volatile element,and its value is not presented in Table 2.

The time variation of 131I inventory in fallout col-lected at meterorological stations Vinča 1 and Bel-grade 1 is shown in Fig. 5. After April 17 the dailydeposition of 131I was below 0.1 Bq/m2.

Fig. 4 Time variation of137Cs activity concentrationin aerosol in daily aerosolsamples measured by VinčaInstitute of Nuclear sciences(Institut Vinca) and mea-sured by Institute for Occu-pational Health Karajovic(Institut Karajovic), 5 h aftersampling; the results aregiven at two-sigma level ofuncertainty

Table 2 134Cs and 137Csactivity and their ratio in theaerosol, monthly samples; theresults are given at two-sigmalevel of uncertainty

Month Station 134Cs (μBq/m3) 137Cs (μBq/m3) 137Cs/134Cs

March Vinča 1 6.3±0.8 8±1 1.3

Vinča 2 12±1 14±2 1.2

Vinča 3 10±1 14±2 1.4

Vinča 4 14±2 16±2 1.1

Belgrade 1 28.0±0.2 32±1 1.1

Belgrade 2 11±2 12±2 1.1

April Vinča 1 27±3 36±4 1.3

Vinča 2 19±2 23±2 1.2

Vinča 3 20±2 24±2 1.2

Vinča 4 17±2 24±2 1.4

Belgrade 1 68±2 87±2 1.3

Belgrade 2 18±2 24±2 1.3

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134Cs inventory was below detection limit (MDC0

0.2 Bq/m2) in all monthly fallout samples, while 137Cswas detected in two samples. MDC for 134Cs is ratherhigh due to small efficiency of the measurementequipment in this energy region and small falloutcollecting area. The results are presented in Table 3(results for 134Cs were omitted since they all are belowMDC) with the uncertainty level of two sigma.

The 131I and 134Cs activities were below detectionlimit in all food and soil samples, exept in one goatmilk sample collected on March 30 in a village nearParaćin where 131I activity was (0.16±0.04) Bq/l.137Cs activity was below detection limit in all foodsamples, but because of its long half-life, it is detectedin the soil samples and will remain for a long timeas a consequence of Chernobyl (Pantelić et al.2000) rather than Fukushima accident. Regardless

of some differences in the absolute values of ac-tivity concentrations, all results, obtained from allsamples and measured in both laboratories, showsimilar pattern increase of values in time to themaximum at about 15–20 days from the date ofthe release of contaminants and after that a slowdecrease, until the values are below MDC.

4 Conclusions

The Fukushima nuclear accident fission products weredetected in the Republic of Serbia, regardless of thegreat distance from Fukushima and the pathway of theair masses. The detected isotopes were 131I, 134Cs and137Cs with the highest activity observed for 131I inaerosol on March 29 and 30. Maximum values for134Cs and 137Cs in aerosol were also on March 29and 30 and on April 8 and 9. The measured radionu-clide concentrations in aerosols were three to fourorders of magnitude lower than the concentraton mea-sured in Belgrade in 1986. after the Cernobyl accident(Todorović 2000; FC 1989), which was expected be-cause of the well-known dilution effects.

Reasonably good agreement between the measure-ment activities of 131I, 134Cs and 137Cs was observed forthe levels measured in aerosol and fallout. The discrep-ancies between the results obtained in two institutes aredue to different climate conditions and different relativeefficiency of the measurement equipment. The 131I and134Cs activities were below detection limit in all foodsamples, except in one goat milk sample collected onMarch 30. From these results, we can conclude that the

Fig. 5 Time variation of131I inventory in fallout inBelgrade, at locations Vinča1 measured by Vinča Insti-tute of Nuclear Sciences(Institut Vinca) and Bel-grade 1, measured by Insti-tute for Occupational HealthKarajovic (Institut Kara-jovic), 5 h after sampling;the results are given at two-sigma level of uncertainty

Table 3 137Cs inventory in fallout, monthly samples; the resultsare given at two-sigma level of uncertainty

Month Station Station 137Cs (Bq/m2)

March Vinča 1 0.24±0.06

Belgrade 1 <0.12

Belgrade 2 <0.03

Lazarevac <0.35

Obrenovac <0.21

April Vinča 1 <0.18

Belgrade 1 <0.24

Belgrade 2 0.21±0.03

Lazarevac <0.44

Obrenovac <0.34

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contamination did occur but in amounts that are notconsidered threatening for the general population.

Since our measurements were carried out as a re-sponse to a potential threat from contamination and onlyin a few locations that cover a small part of our country,the results should be regarded as a preliminary investi-gation. The aim was to establish the method for fastresponse and control in case of contamination. In thatrespect, the number of results obtained is not largeenough for a more in-depth analysis, but can provide avery useful insight, that is to be used for further refin-ment of the monitoring procedures.

Acknowledgments The investigation was partially supportedby the Ministry of Education and Science of the Republic ofSerbia under the following Project III43009.

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