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Journal of Environmental Radioactivity 114 (2012) 94e99

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Journal of Environmental Radioactivity

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Indicators of the Fukushima radioactive release in NW Romania

C. Cosma a, A.R. Iurian a,*, D.C. Nit�a a, R. Begy a, C. Cîndea b

aBabes-Bolyai University, Faculty of Environmental Science and Engineering, 30 Fântânele Street, 400294 Cluj-Napoca, RomaniabCluj County Department of Public Health, 5 Constanta Street, 400158 Cluj-Napoca, Romania

a r t i c l e i n f o

Article history:Received 22 July 2011Received in revised form24 November 2011Accepted 28 November 2011Available online 22 December 2011

Keywords:Fukushima131I134CsTransfer coefficientRainwaterSheep milk

* Corresponding author.E-mail address: iurian.andra@ubbcluj.ro (A.R. Iuria

0265-931X/$ e see front matter � 2011 Elsevier Ltd.doi:10.1016/j.jenvrad.2011.11.020

a b s t r a c t

As a result of the Fukushima nuclear release, 131I was found in different environmental media (rainwater,sheep and cow milk, herbage, sheep meat and thyroid tissue) in north-west Romania. On April 4, 2011a maximum value of 1.40 � 0.21 Bq/L in 131I activity was found in rainwater obtained from the Aradregion. The obtained value corresponded with the maximum of 131I concentration in air, as measured byToma et al. (2011) for the Pitesti area. One day later, sheep milk from the Cluj area was found to containa maximum activity of 9.22 � 0.95 Bq/L. A value of 0.85 � 0.07 mSv was calculated as the total monthlyeffective dose received by the population as a result of the ingestion of sheep milk and sheep meatcontaminated with 131I. Only rainwater samples contained 134Cs and 137Cs at levels close to minimumdetectable activity. Since the determined values could be influenced by Chernobyl 137Cs, the 137Csconcentrations are subject to uncertainty. The radioiodine transfer coefficients (Fm) and the concen-tration ratio (CR) from herbage to sheep milk, as well as sheep meat, from the Cluj-Apahida area are alsopresented.

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1. Introduction

On March 11, 2011, at 14:46, an earthquake with a magnitude of9 on the Richter scale occurred in the Pacific Ocean, and was fol-lowed by a tsunami several hours later. The Japanese Meteorolog-ical Agency estimated a distance of approximately 130 km betweenthe earthquake epicenter and the coast of Sanriku, on the east coastof Japan. These major natural events seriously influenced thecooling systems of the Fukushima Dai-ichi and Fukushima Dai-niNuclear Power Stations (Fukushima NPS), which were in opera-tion during the events. A nuclear accident followed the naturalevents, leading to high releases of radioactive material that span-ned the next several days (Nuclear Emergency ResponseHeadquarters, 2011). High radioactive releases were registered onMarch 15 and 16, 2011 (IAEA, 2011). The Nuclear and IndustrialSafety Agency of Japan estimated a total air discharge from theFukushima Dai-ichi Nuclear Power Station of approximately1.6� 1017 Bq for 131I, and 1.5�1016 Bq for 137Cs (Nuclear EmergencyResponse Headquarters, 2011).

An atmospheric dispersion model of the Fukushima radioactiveplume pathway was compiled by the Federal Institute for Geo-sciences and Natural Resources from Hannover for the time period

n).

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from March 12 to March 28, 2011, by assuming a constant hourlyrelease of radionuclides and a NWeSE direction (BGR Germany,2011). By analyzing backward trajectories, Lozano et al. (2011)found that radioiodine (131I) and cesium (137Cs and 134Cs) concen-trations in air samples collected from the Huelva area in Spain,during the period from March 15e17, 2011 until April 15e17, 2011,originated from Fukushima NPS, Japan. The assumption of thescientific community was that the radioactive cloud from Fukush-ima crossed the North Pacific Ocean and North America, and thatwhen it reached Europe through the Iberian Peninsula it wasdiluted. On Thessaloniki, Greece radioiodine contamination in airwas first detected during March 24e25, 2011 (Manolopoulou et al.,2011). Masson et al. (2011) reported that the Fukushima plume wasdetected in air in all parts of Europe, beginning on March 19, 2011,with a maximum observed in Central Europe. For the Europeanatmosphere, the particulate and gaseous 131I concentration in theair was 3e4 orders of magnitude lower than that following theChernobyl accident in 1986.

In order to determine the best intervention measures followinga nuclear disaster it is important to assess contamination level.Previous studies that conducted in Romania (e.g. Cosma, 2002)determined radioactivity levels in different environmental mediafollowing the Chernobyl accident. The work provided here presents131I, 134Cs, and 137Cs concentrations from the NWpart of Romania invarious environmental media following the Fukushima disaster. Bytaking into account measured 131I activity in fresh herbage and

C. Cosma et al. / Journal of Environmental Radioactivity 114 (2012) 94e99 95

sheepmeat, the transfer coefficients and the concentration ratio forradioiodine were also calculated.

2. Materials and methods

2.1. Sampling

In order to indentify Fukushima radioactivity indicators in thefive counties of Romania’s Nord-West region (Cluj, Bihor, Bistrita-N�as�aud, Maramures, and Arad), a specially organized samplingcampaign began on March 28, 2011. Since they were more acces-sible, the majority of samples were collected from Cluj county. Thesampling locations for each of the environmental media are pre-sented in Fig. 1.

The sampling sites, the dates, and the coordinates obtained fromGPS mobile readings are listed below (Table 1). The rains accom-panying the monitored period allowed the collection of a signifi-cant number of samples (10 samples) from various areas located inNW Romania. For each rain event water was collected in open-endcylindrical samplers with diameters from 22 cm to 40 cm. Asspecified in Table 1, samples from Cluj-Napoca (Cluj county) andArad (Arad county) consisted of rainwater collected on one day.Samples from Vârtop (Bihor county), Nucet (Bihor county), andT�agsoru (Bistrita-N�as�aud county) were collected as a mixture ofrainwater from the entire rain event, corresponding to the samplingtime (Table 1).

Sheep milk was collected from sheep that grazed in open fields,and whose principal daily intake was fresh herbage. Samplinglocations and dates are presented in Table 1. Cow milk from Lomb(Cluj county) was collected on April 6 and 12, 2011 from cows thatwere herded into open pasture on April 10, 2011. Milk samples werenot boiled prior to measurements. Samples of sheep meat andthyroid tissue were obtained from the same herd in Apahida(Cluj county).

Herbage from the Apahida (Cluj county) pasture was milled into0.5mmpieces, until a constant density was reached. Activities weremeasured with gamma spectrometry, without previous drying. Nochemicals were utilized during sample preparation.

2.2. Gamma-spectrometric measurements

Gamma-spectrometric measurements were performed usingtwo high purity germanium detectors (EG&G Ortec; 34.2% and30.0% relative efficiency, respectively) shielded with 10 cm of lead

Fig. 1. Sampling areas and the loc

and 3 mm of copper. In order to obtain 131I activity concentrationsthe 364.5 keV energy line was analyzed. Maestro software wasemployed for the automatic spectrum evaluation. The gamma-linesof 134Cs and 137Cs were also checked for the 604.7 keV and 661 keVenergies, respectively. The samples were measured using Marinelligeometry (0.7 L).

For liquid samples measurements, an aqueous liquid sourcewas prepared by 222Rn gas incorporation into a milk matrix. Forpreparation of the aqueous source, a Marinelli beaker was, first,partially filled with the liquid matrix, and, then, a specific volumeof gaseous radon was added from a calibrated source (regularlyverified in international intercomparison tests). After establishingequilibrium with its progenies, the sealed source was carefullymixed to ensure the homogeneous distribution of radionuclides.The quantitative measurement of radioiodine was performed bycomparing it with the activity of the source using a linear inter-polation of the energy line of 214Pb at 351.9 keV, close to the line of131I at 364.5 keV. The 134Cs and 137Cs concentrations were obtainedin the same manner, by interpolating the energy line of 214Bi at609.3 keV, close to the lines of 134Cs at 604.7 keV and 137Cs at661 keV.

For the herbage (having more than 80% water content), themeat, and the thyroid tissue samples the GES_MC Gamma-electronEfficiency Simulator programme was utilized; in particular, soft-ware designed for gamma radiation measurements (Fulea andCosma, 2009). In each case, obtained activities were decay-corrected to the sampling time (for rainwater, milk, meat, thyroid,and herbage), or to the date of the middle rainfall interval(for several days of mixed rainwater). No summing correctionswere applied for 134Cs.

In order to obtain an uncertainty for the counting statistics of20% (2d), the measurement time ranged from 45,000 s (sheep milkfrom Cluj area) to 112,000 s (rainwater from Cluj-Napoca),depending on sample activity. The minimum detectable activities(MDA Currie limit) of radioiodine in rainwater and milk samples,measured using shielded HpGe detectors, were 0.091 Bq (for theP-type Ortec detector) and 0.050 Bq (for the N-type Ortec detector).The minimum detectable activities for each sample type, as well asfor each of the three isotopes, are provided in the next section.Before the measurements began, the detector’s background spectraregistered 2.65 c/s for the P-type Ortec detector, and 3.9 c/s for theN-type Ortec detector. Background laboratory activity concentra-tions for 131I, 134Cs, and 137Cs measured in Cluj-Napoca have beenbelow MDA values during the last four years.

ation of Romania in Europe.

C. Cosma et al. / Journal of Environmental Radioactivity 114 (2012) 94e9996

3. Results and discussions

3.1. Radionuclides in rainwater

Fukushima fallout was first detected in rainwater samples fromCluj-Napoca (Cluj county) on March 28, 2011, 16 d after the majorreleases started. The obtained 131I activity of 0.055� 0.031 Bq/L wasclose to theMDA. Following this date, activity concentrations of 131I,134Cs and 137Cs were monitored in different environmental mediafor several days, until they decreased below the MDA. Radionuclideconcentrations, amounts of measured samples, and MDA values forevery nuclide and for every environmental indicator are listed inTable 2.

Measurements performed for rainwater suggest thata maximum activity for 131I in the area was likely obtained on April4, 2011 when a value of 1.40 � 0.21 Bq/L was measured in the Aradregion. The value is likely influenced by the atmospheric radio-iodine concentration, by the raining period, or by rainfall intensity.Another maximum for the 131I concentration in rainwater wasfound on April 8, 2011.

The Nuclear Institute from Pitesti-Mioveni (South Romania)performed a local daily survey of Fukushima radioactivity levels inair and wet deposition, for the period from March 23, 2011 to April22, 2011. Higher 131I concentration levels were determined for the11-d period. The temporal distribution was characterized by twoseparate peaks, on March 31, 2011 and April 4, 2011 (Toma et al.,2011). The rainwater activities obtained in this study were ingood agreement with measurements made in the Pitesti area forradioiodine in air (first maximum) and wet deposition during thebeginning of April. At the end of March, the maximum value foundin precipitation in the Pitesti areawas 1.3 Bq/L. Also, the radioiodinecontent of rainwater from Thessaloniki, Greece, following rainfallon March 29, 2011, had values up to 0.7 Bq/L (Manolopoulou et al.,2011).

A second maximum was found for the 131I concentration inrainwater from Vârtop (Bihor county) and Cluj-Napoca(Cluj county), on April 8, 2011, and was not correlated with the131I activity in air in the Pitesti area. Therefore, this maximum doesnot represent the effect of an increase in air 131I activity from thesource (Fukushima NPS). The higher 131I concentration on April 8,2011 may be due to the intensity of rainfall or to changes in the

Table 1Sampling locations in the NW of Romania, characterized by altitude, latitude, and longit

Sampling locations for each sample type Sampling date (2011)

Rainwater

Cluj-Napoca (Cluj county) March, 28Cluj-Napoca (Cluj county) April, 2/5/6/9/13a

Arad (Arad county) April, 5Vârtop (Bihor county) April, 7e8Nucet (Bihor county) April, 5e8T�agsoru (Bistrita-N�as�aud county) (2 samples) April, 9e11

Sheep milkApahida (Cluj county) April, 5/14/19a

Lomb (Cluj county) April, 14Nucet (Bihor county) April, 6T�agsoru (Bistrita-N�as�aud county) April, 10V�aleni (Marmures county) April, 10/16a

Cow milkLomb (Cluj county) April, 6/12a

Sheep meatApahida (Cluj county) April, 20

Sheep thyroidApahida (Cluj county) April, 23

HerbageApahida (Cluj county) April, 14

a One sample per day was taken from the specified location. The sampling days are p

air-mass direction, by considering that the Pitesti and Clujareas are separated by the South Carpathians mountains(2200e2800 m).

Rainwater measurements performed in four Romanian countiesrevealed the presence of Fukushima 131I during the period fromMarch 28, 2011 to April 13, 2011. Low 131I activities were deter-mined for rainwater, with no impact on drinking water. On April 13,2011, one rainwater sample from Cluj-Napoca had a concentrationof 0.25 � 0.09 Bq/L for 131I. After this date no radioiodine could bedetected in precipitation.

Following the Fukushima accident, 134Cs was only observable inrainwater samples from Cluj-Napoca (Cluj county) and Nucet (Bihorcounty). In the Cluj-Napoca area, on March 28, 2011, 134Cs activitiesin rainwater had values of 0.042 � 0.023 Bq/L. Due to its relativelyshort half-life of 2.06 years, it is very unlikely that Chernobyl 134Csstill exists in nature.

The small 137Cs values that were determined after the Fukush-ima accident in rainwater samples, and presented above, could beinfluenced by 137Cs tracers from Chernobyl fallout, and may not bereliable. Unfortunately, no data were available in the studied areafor pre-Fukushima 137Cs activities in rainwater. The Chernobylaccident caused large amounts of cesium discharge in the atmo-sphere (UNSCEAR, 2000), and the Romanian territory was exposedto high radioactivity values (Cosma, 2002). Chernobyl 137Cs, havinga half-life of 30.06 years, could be found in open-air due to theresuspension of soil particles. As such, the values found for 137Csactivity concentrations in rainwater could result both from Cher-nobyl and Fukushima. Since the resulting 137Cs activities had verylow values, close to the MDA, a clear differentiation between eachcontribution could not be performed.

3.2. Milk concentration of 131I

Several samples of cow and sheep milk were measured, fromdifferent areas in NW Romania, beginning on April, 5 2011. Theresultant values are presented in Table 2. The highest 131I activitywas found in sheep milk that was collected on April 5, 2011 fromApahida (Cluj county). The obtained value was 9.22 � 0.95 Bq/L,which also represents the first measurement performed in this areafor sheep milk following Fukushima fallout. Due to a short 131I half-life of 8.02 days, the milk collected from sheep grazing from the

ude.

Altitude (m) Latitude Longitude

350 N 46�4601500 E 23�3300400

350 N 46�4601500 E 23�3300400

112 N 46�1001600 E 21�1805700

1150 N 46�3004800 E 22�4005600

460 N 46�2805100 E 22�3501600

444 N 46�4703500 E 24�1401400

362 N 46�4801100 E 23�4500900

443 N 46�4602700 E 23�3300100

460 N 46�2805100 E 22�3501600

444 N 46�4703500 E 24�1401400

529 N 47�4700000 E 24�0100600

443 N 46�4602700 E 23�3300100

362 N 46�4801100 E 23�4500900

362 N 46�4801100 E 23�4500900

362 N 46�4801100 E 23�4500900

resented between the slashes.

Table 2Measured radionuclide activities in rainwater, sheep milk, cow milk, sheep meat, sheep thyroid, and herbage from different locations in NW Romania.

Sampling locations foreach sample type

Sampling period/Dateof sampling (2011)

Amount ofmeasured sample

131I activity (Bq/Lor Bq/kg)

134Cs activity (Bq/Lor Bq/kg)

137Cs activity (Bq/Lor Bq/kg)

MDA for 131I(Bq/L or Bq/kg)

RainwaterCluj-Napoca (Cluj county) March, 28 0.700 L 0.055 � 0.031 0.042 � 0.023 0.048 � 0.022 0.050Cluj-Napoca (Cluj county) April, 2 0.700 L 0.60 � 0.11 0.054 � 0.035 0.067 � 0.026 0.050Arad (Arad county) April, 4 0.500 L 1.40 � 0.21 <0.034b <0.039c 0.050Cluj-Napoca (Cluj county) April, 5 0.500 L 0.53 � 0.11 <0.034b <0.039c 0.050Cluj-Napoca (Cluj county) April, 6 0.600 L 0.50 � 0.10 <0.034b <0.039c 0.050Nucet (Bihor county) April, 5e8 0.700 L 0.72 � 0.12 0.045 � 0.025 0.078 � 0.031 0.050Vârtop (Bihor county) April, 7e8 0.700 L 1.69 � 0.25 <0.034b <0.039c 0.050Cluj-Napoca (Cluj county) April, 9 0.330 L 1.38 � 0.21 <0.034b <0.039c 0.050T�agsoru (Bistrita-N�as�audcounty) (2 samples)a

April, 9e11 0.700 L 0.38 � 0.07 <0.034b <0.039c 0.050

Cluj-Napoca (Cluj county) April, 13 0.700 L 0.25 � 0.09 <0.034b <0.039c 0.050Sheep milkApahida (Cluj county) April, 5 0.530 L 9.22 � 0.95 <0.031b <0.039c 0.050Nucet (Bihor county) April, 6 0.700 L 4.01 � 0.70 <0.031b <0.039c 0.050T�agsoru (Bistrita-N�as�aud county) April, 10 0.700 L 3.80 � 0.69 <0.051b <0.059c 0.091V�aleni (Marmures county) April, 10 0.700 L 3.70 � 0.66 <0.051b <0.059c 0.091Apahida (Cluj county) April, 14 0.320 L 3.80 � 0.64 <0.051b <0.059c 0.091Lomb (Cluj county) April, 14 0.700 L 3.21 � 0.71 <0.031b <0.039c 0.050V�aleni (Marmures county) April, 16 0.700 L 2.35 � 0.47 <0.031b <0.039c 0.050Apahida (Cluj county) April, 19 0.620 L 1.92 � 0.42 <0.031b <0.039c 0.050

Cow milkLomb (Cluj county) April, 6 0.700 L <0.062 <0.030b <0.033c 0.062Lomb (Cluj county) April, 12 0.700 L 0.37 � 0.13 <0.030b <0.033c 0.062

Sheep meatApahida (Cluj county) April, 20 0.425 kg 0.36 � 0.12 <0.039b <0.042c 0.701

Sheep thyroidApahida (Cluj county) April, 23 0.079 kg 180.7 � 6.3 <0.039b <0.042c 0.701

HerbageApahida (Cluj county) April, 14 0.042 kg 2.55 � 0.51 <0.030b <0.033c 0.065

a The mean of two samples is presented.b MDA value for 134Cs.c MDA value for 137Cs.

C. Cosma et al. / Journal of Environmental Radioactivity 114 (2012) 94e99 97

same pasture-land in Apahida (Cluj county), over a 14-day period,displayed a significant attenuation for 131I concentrations.

The maximum 131I concentration in sheep milk, from April 5,2011, was higher than themaximum one reported in Giove, Italy formilk (5.24 � 0.60 Bq/L), corresponding to the same date (ISPRA,2011). The higher value obtained for 131I in sheep milk could bedue to the fact that approximately 100% of the dietary daily intakeof Apahida (Cluj county) sheep originated from fresh herbage. OnApril 14, 2011, Pittauerová et al. (2011) determined a value of0.08 � 0.02 Bq/kg for 131I in cattle milk, from an area where onlyapproximately 50% of the cattle’s daily diet in early April originatedfrom fresh grass. In Romania, in early May 1986, the maximumconcentration of radioiodine was 10 kBq/L in sheep milk, and1.37 kBq/L for consumer milk (Sonoc et al., 1995).

Panariti (1995) found that radioiodine was detected in sheepmilk 12s he24 h subsequent to herbage contamination. Based onthis experiment, a correlation can be made between the maximum131I activity found on April 4, 2011 in rainwater samples from Cluj-Napoca, and the 131I concentration in sheep milk from Apahida(Cluj county) on April 5, 2011.

One milk sample from un-pastured cow was measured on April6, 2011. In this sample, the 131I concentration had a value below theMDA. Several days later, on April 12, 2011, a value of 0.37� 0.13 Bq/Lwas found for 131I in cow milk from Lomb (Cluj county). Unlike

Table 3The weekly ingestion dose received by the local population eating sheep milk and meat

Sample description 131I activity Ingestion convfactor (Sv/Bq)

Sheep milk 4.00 � 0.61 Bq/L 22 � 10�9

Sheep fresh meat 0.36 � 0.12 Bq/kg

sheep, the daily dietary intake of cows herded in open pasture fromApahida (Cluj county) during early spring (March and April)consists of approximately 25% fresh herbage. The grazing patternclearly influenced the lower 131I activity in cowmilk as compared to131I concentrations in sheep milk, when considering that bothgrazed in open pasture.

In Romania, the National Commission for Nuclear ActivitiesControl set an admissible intake limit for milk products of 500 Bq/kg for 131I, and a limit of 370 Bq/kg for cesium (134Cs and 137Cs)(CNCAN, 2002). The limits can be applied to concentrated andanhydrous products and can be calculated according to therestructured product prepared for consumption. The limit is 66%higher than the Japanese maximum admissible limit for radio-iodine that was set in 2011 (300 Bq/L) (Ministry of Health, Labourand Welfare Japan, 2011). The values determined in Romaniansheep and cow milk following the Fukushima accident are muchlower than themaximum intake limits. No traces of cesium or otherartificial radionuclides were found in milk samples.

3.3. The transfer coefficients for radioiodine

The contamination of animal fodder, and hence animal productsfollowing radioactive fallout, is a key consideration when deter-mining internal doses to humans due to the natural food chain. The

contaminated with 131I.

ersion Estimated foodconsumption/week

Weekly 131I ingestiondose (mSv)

3 L 0.26 � 0.041 kg 0.08 � 0.03

Table 4131I activities and transfer coefficients for radioiodine.

Sample description 131I activity Transfer coefficients(Fm)

RecommendedFm valuesa

Concentrationratiob (CR)

1 Herbage (fresh meadow grass) 2.55 � 0.51 Bq/kg2 Sheep milkc 3.80 � 0.64 Bq/L 2.13 � 10�1 d/L 3.0 � 10�2�9.4 � 10�1 d/L 8.52 � 10�1 kg/L3 Sheep fresh meat 0.36 � 0.12 Bq/kg 2.03 � 10�2 d/kg 3.0 � 10�2 d/kg 8.13 � 10�2

a Howard et al. (2009); IAEA (2010).b CR is based on fresh weight concentrations of food product and dry weight concentrations of herbage.c The specified value corresponds to the middle date of the milk measurement period.

C. Cosma et al. / Journal of Environmental Radioactivity 114 (2012) 94e9998

oral pathway, by ingestion of milk or other foodstuffs contaminatedwith 131I, is the main route for the internal exposure of the pop-ulation (UNSCEAR, 2000). The estimated effective ingestion dosecan be calculated by taking into account the 131I activity concen-tration in food (Bq/kg), the amount of contaminated foodconsumed (kg), and the ingestion conversion factor for 131I (22 nSv/Bq) (IAEA, 1996). Estimated weekly doses received by the localpopulation consuming contaminated sheep milk and meat in themiddle of April 2011, are provided in Table 3.

The 131I activity in sheep milk was considered as an averagevalue for 131I concentrations for approximately one week, includingthe period from April 5, 2011 to April 19, 2011. If one considers thatfor the other three weeks of the same month, the weekly 131Iingestion dose decreased to half of the obtained value, then, thetotal monthly 131I ingestion dose was 0.85 � 0.07 mSv. After onemonth, from the first 131I detection in NW Romania, one canassumes that, in the future, no contribution of Fukushima 131I to theingestion dose received by the local population will be evident.

The total monthly effective dose due to the ingestion of sheepmilk and sheep meat contaminated with 131I is much lower thanthe monthly recommended generic reference level of approxi-mately 0.83 mSv (the annual dose is approximately 10 mSv) forintervention in prolonged exposure situations, set by the Interna-tional Commission on Radiological Protection (ICRP82, 1999). Also,the estimated monthly ingestion dose is lower than the monthlyeffective dose due to natural radiation by ingestion, which rangesbetween 0.016 and 0.083 mSv (annual dose 0.2e1 mSv) (UNSCEAR,2008).

In order to estimate radioiodine transfer coefficients (Fm) fromherbage to animals, samples of fresh meadow grass, milk, andsheep meat were taken from the same contaminated area in Apa-hida (Cluj county). The transfer coefficients are defined as the ratiobetween the radionuclide activity concentration in milk and thedaily dietary radionuclide intake (Ward and Johnson, 1965). Thesame authors also defined the meat transfer coefficient as the ratioof the radionuclide activity concentration in boneless meat to thedietary daily radionuclide intake. A major source of uncertainty inFm estimations is the determination of the daily radionuclideintake for agricultural animals which varies according to thefeeding strategy of the farmer’s dry matter digestibility. That thedietary composition for agricultural animals varies between andwithin countries, and also with season is well known (Howardet al., 2009). Using farmer’s information regarding the dietarycomposition of the sheep from Apahida (Cluj county), the dailydietary intake was determined to be 7 kg dry herbage. Otheradditional nutrients do not have an important contribution to thedaily dietary composition of sheep from Apahida (Cluj county).

Determining transfer coefficients for the assessment of long-term contamination is important because the conditions thatresult from experimental contamination are not always as relevantas the indigenous conditions created by accidental radionucliderelease (Sheppard et al., 2010;Whicker et al., 2001). However, sinceit varies with the animal body mass and the dietary intake rate, thetransfer coefficient has a disadvantage. An alternate method to

quantify the transfer from herbage to animal product is theconcentration ratio (CR), which is the equilibrium ratio of theradionuclide activity concentration in the food product (freshweight) divided by the radionuclide concentration in drymass feed.CR values can be derived by multiplying the transfer coefficientvalue by the daily dietary intake in kg/d (Howard et al., 2009; IAEA,2010; Sheppard et al., 2010). The CR has an advantage in that thedietary dry matter intake does not need to be calculated (IAEA,2010) if the dry daily dietary radioiodine intake from nutritionreviews is considered. Sheppard et al. (2010) suggested that unlikethe transfer coefficients the CR value for a given element may, ingeneral, be consistent across species.

According to previous studies, 131I is rapidly adsorbed and fixedin the structure of plant leaves and only a small fraction can beremoved by water (Heinemann and Vogt, 1980). Hence, even if thecontaminated area was washed by rain several times duringthe studying period (March 28, 2011eApril 13, 2011), most of theradioiodine remained on the herbage, and had a high probability ofbeing grazed. In Table 4, the radioiodine activities and the transfercoefficients from herbage to sheep milk and sheep meat in theApahida (Cluj county) area are presented. The 131I activities in freshherbage could be influenced by local 131I deposition or by thecollectable mass per area. Unfortunately, no other measurementson fresh grass were made to confirm this assumption. Pittauerováet al. (2011) reported considerable variety between radionuclide(131I, 134Cs, 137Cs) activities in grass from three different locations inGermany on different sampling dates. On April 13, 2011, a value of3.58 � 0.13 Bq/kg was reported for Schiffdorf grass.

For the radioactive isotope of iodine, Fm values (for milk andfresh sheep meat) are comparable to those previously published,and with the revised recommended transfer coefficient valuespresented in the IAEA handbook on transfer parameters (Howardet al., 2009; IAEA, 2010). Most of the available data on the radio-nuclide transfer to sheepmilk are largely derived from experimentswith oral administration. Howard et al. (1993), based ona controlled experiment with measured intakes of Chernobyl-contaminated herbage, reported an Fm value of 2.9 � 10�1 d/L.The obtained concentration ratio for 131I in sheep milk lies withinthe IAEA’s recommended values, with a minimum of 2.5 � 10�1 kg/L and amaximum of 8.8� 10�1 kg/L (IAEA, 2010). For radioiodine insheep meat, there is no CR recommended value available in theliterature.

Following the Chernobyl accident, the consumption of freshmilk contaminated with 131I had the largest contribution to thethyroid dose (UNSCEAR, 2000). In order to establish the thyroidaccumulation of radioiodine for sheep, a thyroid sample wasmeasured on April 23, after more than 17 days of radioactive 131Ideposition in the area (from March 28, 2011 to April 13, 2011). Thesheep thyroid concentration of 131I (180.7 Bq/kg) was higher, bya factor of 70, than the radioiodine activity in fresh meadow grass.Due to the rapid transfer of radioiodine throughout the sheep foodchain, doses accumulated rather quickly in thyroid tissue. Thelargest difference between these two values is due to the contin-uous accumulation of radioiodine over the exposure period.

C. Cosma et al. / Journal of Environmental Radioactivity 114 (2012) 94e99 99

4. Conclusions

Beginning on March 28, 2011, Fukushima 131I was detected attrace levels in all of the rainwater and milk samples collected fromNW Romania. The obtained radioiodine concentrations are compa-rable with those reported in other European countries (Greece,Germany, and Italy), and are much lower than the maximum levelsset by Romanian authorities, with no concern for the public. Themaximum value determined on April 4, 2011 in rainwater wascorrelated with the maximum 131I activity in air as measured byToma et al. (2011) in the Pitesti area in South Romania. On April 5,2011, sheep milk from the Cluj area showed a maximum 131Iconcentration of 9.22 � 0.95 Bq/L. The total monthly effective dosereceived by the population due to the ingestion of sheep milk andsheepmeat contaminated with 131I was found to be 0.85� 0.07 mSv.

Cesium-134 was found only in rainwater samples from Cluj-Napoca (Cluj county) and Nucet (Bihor county). Due to the resus-pension of 137Cs in the atmosphere, following the Chernobyl acci-dent, the low values (close to MDA) registered for this radionuclidein rainwater are subject to uncertainty.

The transfer factors (Fm) for radioiodine are important whenconsidering the natural food chain, and were obtained for sheepmilk (2.13 � 10�1 d/L) and sheep meat (2.03 � 10�2 d/kg). Thecalculated values are comparable with the revised recommendedtransfer coefficient values presented in the IAEA handbook ontransfer parameters (Howard et al., 2009; IAEA, 2010).

Acknowledgement

This paper was realized with the support of the POSDRUCUANTUMDOC “Doctoral Studies for European Performances inResearch and Innovation” project - ID79407 and of the EURODOC“Doctoral Scholarships for research performance at European level”project e ID 59410, funded by the European Social Fund andRomanian Government.

The authors much appreciate the reviewers’ suggestions inimproving the quality of the present work.

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