In this work, a study of the radioactive content of some spring and bottled mineral waters originating fi-om metamorphic rock areas was carried out. A high content of radium isotopes (Ra-226, Ra-228), was found by radiometric analysis in the spring waters: Studenica (Ra-226: 289 mBq/L), Cibutkovica (Ra-226: 92, 4 mBq/L, Ra-228: 610 mBq/L), and Crni Guber (Ra-226: 120 mBq/L, Ra-228: 1170 mBq/L). On the other hand, the radiochemical results showed a higher concentration of U-238 in the bottled mineral water samples (dissolved uranium concentrations were from 0.21 mBq[L, for Kopaonik to 71.5 mBq/L fo Skadarska) than in the spring water samples (dissolved uranium concentrations were very low approximate to 10 mBq/L). The concentrations of all the present naturally occuring radionuclides: U-238, U-234, Th-232, Th-230, Th-228, Ra-228 and Ra-226 were determined by alpha/gamma spectrometric analysis. The activity ratios U-234/U-238, Ra-226/Th-230 and Th-228/Th-232, Ra-228/Th-228 were calculated and are discussed as an indication of the radioactive disequilibrium in bothe the U-238 and Th-232 radioactive series. The high contents of radium isotopes with respect to the equilibrium values expected from the respective parents Th-232/(Th-232 series) and Th-230 (U-238 series) found in the spring water samples is the main evidence for the existence of significant radioactive disequilibrium in both the radioactive series

Joksić, Jasminka D.

Miljanić, Šćepan S.

Radenković, Mirjana

Journal of the Serbian Chemical Society

In this work, a study of the radioactive content of some spring and bottled mineral waters originating frommetamorphic rock areas was carried out.Ahigh content of radium isotopes (226Ra, 228Ra), was found by radiometric analysis in the spring waters: Studenica (226Ra: 289 mBq/L), ^ibutkovica (226Ra: 92, 4 mBq/L, 228Ra: 610 mBq/L), and Crni Guber (226Ra: 120 mBq/L, 228Ra: 1170 mBq/L). On the other hand, the radiochemical results showed a higher concentration of 238U in the bottled mineral water samples (dissolved uranium concentrations were from 0.21 mBq/L, for "Kopaonik" to 71.5mBq/L fo "Skadarska") than in the spring water samples (dissolved uranium concentrations were very low » 10 mBq/L). The concentrations of all the present naturally occuring radionuclides: 238U, 234U, 232Th, 230Th, 228Th, 228Ra and 226Ra were determined by alpha/gamma spectrometric analysis. The activity ratios 234U/238U, 226Ra/230Th and 228Th/232Th, 228Ra/228Th were calculated and are discussed as an indication of the radioactive disequilibrium in bothe the 238U and 232Th radioactive series. The high contents of radium isotopes with respect to the equilibrium values expected from the respective parents 232Th/(232Th series) and 230Th (238U series) found in the spring water samples is the main evidence for the existence of significant radioactive disequilibrium in both the radioactive series

SCEPAN S. MILJANIC

MIRJANA B. RADENKOVIC

JASMINKA D. JOKSIC

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Natural radioactivity of some spring and bottled mineral waters from several central Balkan sites, as a way of their characterization

Jasminka Joksic

Mirjana Radenkovic

Scepan Miljanic

Crossref

Natural radioactivity of some spring and bottled mineral waters from several Central Balkan sites, as a way of their characterization

Repository of the Vinča Nuclear Institute (VinaR)

J. Serb. Chem. Soc. 72 (6) 621–628 (2007) UDC 553.76:626.812:663.646:543.4/.5(497)JSCS–3594 Original scientific paperNatural radioactivity of some spring and bottled mineralwaters from several central Balkan sites, as a way oftheir characterizationJASMINKA D. JOKSI]1*, MIRJANA B. RADENKOVI]1 and []EPAN S. MILJANI]21Vin~a Institute of Nuclear Sciences, Radiation and Environmental Protection Laboratory, P. O.Box 522, 11001 Belgrade, Serbia and 2University of Belgrade – Faculty of Physical Chemistry,P. O. Box 137, 11001 Belgrade, (e-mail: jasnaj@vin.bg.ac.yu)(Received 14 May, revised 28 June 2006)Abstract: In this work, a study of the radioactive content of some spring and bottledmineral waters originating from metamorphic rock areas was carried out. Ahigh contentof radium isotopes (226Ra, 228Ra), was found by radiometric analysis in the spring wa-ters: Studenica (226Ra: 289 mBq/L), ^ibutkovica (226Ra: 92, 4 mBq/L, 228Ra: 610mBq/L), and Crni Guber (226Ra: 120 mBq/L, 228Ra: 1170 mBq/L). On the other hand,the radiochemical results showed a higher concentration of 238U in the bottled mineralwater samples (dissolved uranium concentrations were from 0.21 mBq/L, for "Ko-paonik" to 71.5 mBq/L fo "Skadarska") than in the spring water samples (dissolved ura-nium concentrations were very low  10 mBq/L). The concentrations of all the presentnaturally occuring radionuclides: 238U, 234U, 232Th, 230Th, 228Th, 228Ra and 226Rawere determined by alpha/gamma spectrometric analysis. The activity ratios 234U/238U,226Ra/230Th and 228Th/232Th, 228Ra/228Th were calculated and are discussed as an indi-cation of the radioactive disequilibrium in bothe the 238U and 232Th radioactive series.The high contents of radium isotopes with respect to the equilibrium values expectedfrom the respective parents 232Th/(232Th series) and 230Th (238U series) found in thespring water samples is the main evidence for the existence of significant radioactivedisequilibrium in both the radioactive series.Keywords: radioactivity: spring waters, mineral bottled waters, spectometry analy-sis, radioactive equilibirum, activity rations.INTRODUCTIONDue to the importance of drinking water for human life and the increased con-sumption of mineral waters, their quality must be carefully and systematically con-trolled. The recommended control of radioactivity levels in existing or new drink-ing water includes total alpha/beta activity measurements, as an indication of po-tentially enhanced radioactivity. In order to guarantee an exposure lower than 0.1621doi: 10.2298/JSC0706621J* Corresponding author.mSv/y, radioactivity levels for drinking water, recommended by the WHO (WorldHealth Organization), are 0.1 Bq/L for the gross alpha and 1 Bq/L for the gross betaactivity. The guideline levels are calculated using a water consumption rate of 2 Ldaily. For natural mineral waters, the measurement on the naturally occurringradionuclide 40K, which makes up about 0.12 % of natural potassium, is obligatory.1If the gross alpha and/or gross beta activity exceed the recommended values of0.1 Bq/L and 1 Bq/L, respectively, the contents of specific radionuclides have to bedetermined by alpha and/or gamma spectrometric measurements.During routine analysis of water samples mainly from Serbia, only a few samplesof spring waters were found to be above the limits of 1Bq/L for beta and 0.1 Bq/L foralpha activity. These are the waters from Serbia (Studenica, ^ibutkovica) and one fromBosnia and Herzegovina (Crni Guber). The distribution of naturally occurring radi-onuclides 238U, 234U, 232Th, 230Th, 228Th, 228Ra and 226Ra in these waters, obtainedby spectrometric analysis, gave evidence of very interesting cases of disequilibrium ofradioactive series in the 238U and 232Th decay chains. Since the consumption of springand mineral waters is continuously growing in most regions in Europe, the monitoringof the radioactivity of drinking water is becoming more important.2–4 Knowledge ofthe concentrations of uranium and radium in drinking water is important because anappreciable fraction of the absorbed uranium and radium is deposited in bones, with acorresponding contribution to the internal dose.5The objective of this study was to determine the concentrations of naturalradionuclides in some spring and some bottled mineral waters, and to comparethem with other studies conducted in the region and to discuss the obtained radio-activity ratios 234U/238U, 226Ra/230Th and 228 Th/232Th, 228Ra/228Th.EXPERIMENTALSpring water samples were taken at the locations of Studeni~ki izvori and Lazarevac (Serbia)and Srebrenica (Bosnia and Herzegovina). A map of the sampling sites is shown in Fig. 1.Spring water samples of 10 L were first acidified to pH 2 and then preconcentrated by evapora-tion under an infrared light to about 450 mL (Table I).6TABLE I. Characteristics of the spring mineral watersName Location Type of water Geological setting of aquiferStudeni~ki izvori Studeni~ka reka, Studenica HCO3–Na Various schists^ibutkovica Reka Grabovica, Lazarevac HCO3–Na Limestone crystalline schiestsCrni Guber Srebrenica HCO3–Na BauxiteThe studied commercially available bottled natural mineral waters are summarized in Table II,together with some basic data on the aquifers. Water samples(8–12L) are acidified to pH 2 andpreconcentrated by evaporation under an infrared light to 450 mL.After preconcentration, all water samples were sealed into Marrineli beakers and left for 28days to reach the radioactive equilibrium betweeen 226Ra and daughters (214Bi and 214Pb). Gam-ma-spectrometric measurements were performed using a HPGe Canberra detector with a countingefficiency of 23 %. The activity of 228Ra was determined indirectly from its daughter, the 228Ac iso-622 JOKSI], RADENKOVI] and MILJANI]tope (338.4 keV and 911.2 keV energies). The radium isotope 226Ra was determined from its daugh-ters 214Pb (295.1 keV and 351.9 keV) and 214Bi (609.3 keV, 1120.3 keV and 1764.5 keV). The 40Kactivity was determined from the 1460.8 keV energy line.TABLE II. Characteristics of the Serbian bottled mineral watersTrade name Location Under-grounddepth/mType of water Geological settings ofaquifer"Mivela" Velu}e 90–120 HCO3–Na,Mg Various schists"Karadjordje" Smederevska Palanka 10–12 HCO3–Na,Mg,Ca Limestone crystallineschists"Kopaonik" Brus 700 HCO3–Na Limestone,vulcanites"Prolom: Prolom Spa 200 HCO3–Na Vulcanites"Skadarska" Skadarlija Brewery 61 HCO3,SO4–Ca,Mg Karstified limes"Heba" Bujanovac Spa 200 HCO3–Na Crystalline schistsThe preparation of thin-layer radioactive sources for alpha-spectrometric analysis included theprior radiochemical procedure of separation of uranium and thorium from the sample matrix and puri-fication from each other and finally electroplating onto stainless steel discs.7 Low-level activity mea-surements were performed using a Canbera alpha-spectrometry counting system, consisting of a vac-uum chamber (20 mbar), PIPS-detector (300 mm2 surface), with a counting efficiency of 15 % at a dis-tance of 25 mm, a multichannel energy scale of 9.1 keV/ch and a resolution of 24 keV for 241Am.The water samples were pretreated by evaporating to dryness and ashing with NaNO2, at 550°C. After precipitation of the hydroxides, the ion-exchange extraction of uranium and thorium fromthe matrix and separation and fractionation was performed using a DOWEX 14 (100–200 mesh)chloride-conditioned resin. A further eluation on the ion-exchange resin was required for the purifi-cation of the obtained uranium and thorium fractions. After extraction of iron, thin-layer radioactivesources for alpha-spectrometry measurements were obtained from the uranium fraction by theNATURAL RADIOACTIVITY OF WATERS FROM CENTRAL BALKAN 623Fig. 1. Map of Serbia and its vicinity; location ofthe investigated water resources are marked.Talvities electroplating procedure. The talvities procedure was also employed for the thorium frac-tion but the obtained sources had to be covered by VINS foil before measurements to prevent detec-tor contamination by recoil.To obtain the radiochemical yield 232U and 229Th standard tracer solution (Harwell Labora-tory, UKAEA, England) were added to each sample.RESULTS AND DISCUSSIONThe gross alpha and beta activaties of the analyzed bottled mineral waterswere within the recommended values, except for the "Heba" and "Karadjordje"samples, where the beta activities were enhanced due to the 40K concentration of1530 and 2800 mBq/L, respectively. The high values of the total alpha and totalbeta activities found in three of the examined natural spring water originating fromthe metamorphic rock area, having a similar chemical compositions (carbon-acid),are due to the high content of naturally occuring radionuclides of the 238U and232Th series. The contect of racionuclides in bottled and spring mineral waters ob-tained by alpha and gamma spectrometry are summarized in Table III.It can be seen that the 238U and 234U isotope concentrations in the bottled waters(dissolved uranium concentrations were very low  10 mBq/L) are higher than in thesamples of spring water (dissolved uranium concentrations range from 0.21 mBq/Lfor "Kopaonik" to 71.5 mBq/L for "Skadarska"). These uranium concentrations arecomparable with some others from the region.3,4 They are even lower than those in624 JOKSI], RADENKOVI] and MILJANI]Fig. 2. a) Total urani-um content (ppm) andb) 234U/238U activityratio in the measuredmineral bottled andspring waters.TABLEIII.Activities(mBq/L)ofuranium,thoriumandpotassiumisotopesintheinvestigatedwatersamplesWaterSampleU-238U-234U-235Th-232Th-230Th-228Ra-228Ra-226K-40"Mivela"0.29±0.060.21±0.07<0.02<0.86<0.8614±5<3<26155±26"Karadjordje"7.61±1.005.05±0.750.22±0.11<0.2<0.24.75±0.53<326280±400"Kopaonik"0.21±0.18<0.16<0.02<0.2<0.24.75±0.5318±529±7300±31"Prolom"9.38±1.1018.9±2.10.34±0.1<0.4<0.210.4±1.9M3<26<70"Skadarska"43.4±4.626.3±2.81.8±0.4<0.06<0.066.91±0.85<334±5230±8"Heba"0.22±0.050.73±0.11<0.05<0.05<0.0515.04±1.62100±1560±61530±30CrniGuber5.36±1.06.6±1.3<0.371.20±0.4<0.24152±181170±110120±16750±12Studenica3.80±0.464.7±0.60.17±0.040.44±0.100.350±0.086.00±0.77<202280±2541700±260^ibutkovica2.20±0.22.1±0.2<0.20.90±0.32.4±0.548.9±4.0610±20092.4±30.51670±120some bottled waters from Northen Italy.8 The 234U/238U activity ratio values in thebottled samples were within the range from 0.6–3.3, which is in accordance with thereported results.8,9 However, the low content of 238U in the "Heba" (0.22 mBq/L)and "Prolom" (9.38 mBq/L) samples corresponds to a 234U/238U ratio greater than 1(2 and 3.3, respectively), Fig. 2. The 234U excess compared to the 238U content inwaters may be explained by in situ leaching through alpha-recoil tracks.10 The samecorrelation in well waters was attributed to the changes in the oxidizing/reducingconditions of the aquifer environment,11 being characteristic in oxidizing zones.12Elevated temperatures and strong reducing conditions usually result in the oppositerelations, due to the acceleration of isotope exchange processes.13The 234U/238U ratios obtained for the spring waters Crni Guber, Studenica and^ibutkovica were 1.22, 0.95 and 1.24, respectively, indicating the 238U series ra-dioactive equilibrium.The content of 226Ra and 228Ra isotopes, originating from the 238U and 232Thdecay series, was quite low in the analyzed bottled mineral waters, compared to thevalues obtained for other bottled mineral waters3,4 and the investigated spring wa-ters (Crni Guber, Studenica and ^ibutkovica).The spring water samples were poor in uranium and rich in radium. The highestconcentrations of the Ra isotopes were found in the limestone regions, where Ra ismore soluble in HCO3– waters.9 The values obtained show that a large a amount of226Ra does not necessarily indicate a high 238U content, since the radium may migrateand be deposited randomly from the surrounding rock areas.14 In geothermal sources,where the temperature is high and the concentration of chlorine elevated and the reduc-ing potential is very weak, the 226Ra/238U ratios are often high,15 even in the order of103–104.16 In a reducing medium, with uranium less mobile than radium, the disap-pearance of sulphates allows high radium concentrations in solution.17The high content of radium isotopes with rescept to the equilibrium values, ex-pected from the parent isotopes 232Th(232Th series) and 230Th(238U series), foundin the spring water samples, are evidence of the existence of a significant radioac-tive disequililbrium in both radioactive series.The 226Ra concentration in the spring mineral waters, exceeding the equilib-rium value corresponding to the 230Th content, with 226Ra/230Th ratios of 38.5 and6514 (Table IV), for the ^ibutkovica and Studenica samples, respectively, show asignificant of disequilibrium level of the 238U series.TABLE IV. Radioactivity ratios of radionuclides from the 238U and 232Th series in the spring watersamplesMineral water 234U/238U 226Ra/230Th 228Th/232Th 228Ra/228ThCrni Guber 1.24 / 126.7 7.7Studenica 1.24 6514 13.6 /^ibutkovica 0.95 38.5 54.3 12.4626 JOKSI], RADENKOVI] and MILJANI]Considering the 232Th series, the 228Ra/228Th and 228Th/232Th ratios obtainedfor the spring waters were much higher than expected from the amounts determinedfor the parent isotopes (Table IV). The 228Ra excess in the waters may be attributedto the different solubility of thorium and radium and a partly upward diffusion fromthe surrounding sediments.9 In the decay process from 232Th to 228Th, the 228Raradionuclide (t1/2 = 5.75 y) is in the middle. Since the chemical properties of radiumand thorium are different, the high 228Th content derives from 228Ra.CONCLUSIONRadiochemical analyses of some natural mineral bottled waters from severallocations in the central Balkan area showed the presence of naturally occurringradionuclides from both the 238U and 232Th series. The relevant activity ratios234U/238U, 226Ra/230Th, 228Th/232Th, 228Ra/228Th were indicative of radioactivedisequilibrium, especially in the spring water samples.Higher 238U activities in some bottled, when compared with the examinedspring waters, show the reverse trend in the 238U activity versus the 234U/238U ac-tivity ratio. The 238U and 234U isotope concentrations in the bottled waters werefound to be up to 71.5 mBq/L.The contents of 226Ra and 228Ra isotopes were quitelow and, in some cases below the detection limit.The very high 226Ra and 228Ra activities in the spring waters do not necessar-ily indicate high concentrations of their parents in the 238U and 232Th series.The analyzed water samples are selected for analysis due to their enhancedgross alpha/beta activity. The study gives a contribution to the radionuclides map-ping of natural mineral waters in metamorphic petrology areas.I Z V O DPRIRODNA RADIOAKTIVNOST NEKIH IZVORSKIH I FLA[IRANIHMINERALNIH VODA SA NEKOLIKO LOKACIJA NA CENTRALNOMBALKANU, KAO NA^IN WIHOVE KARAKTERIZACIJEJASMINKA D. JOKSI]1, MIRJANA B. RADENKOVI]1i []EPAN S. MIQANI]21Institut za nuklearne nauke Vin~a, Laboratorija za za{titu od zra~ewa i za{titu `ivotne sredine"Za{tita", P. P. 522, 11001 Beograd i2Univerzitet u Beogradu – Fakultet za fizi~ku hemiju, P. P. 137,11001 BeogradU ovom radu su prikazani rezultati ispitivawa sadr`aja radionuklida u nekimizvorskim i fla{iranim mineralnim vodama koji poti~u iz metamofrnih oblasti. Uizvorskim mineralnim vodama je izmeren visok sadr`aj radijumovih izotopa (226Ra,228Ra): Studenica (226Ra: 2280 mBq/L), ^ibutkovica (226Ra: 92,4 mBq/L, 228Ra: 610 mBq/L) iCrni Guber: (226Ra: 120 mBq/L, 228Ra: 1170 mBq/L). Sa druge strane, ve}a koncentracija238U je detektovana u fla{iranim mineralnim vodama (koncentracije uranijuma sekre}u od 0,21 mBq/L za "Kopaonik" do 71,5 mBq/L za "Skadarsku") nego u izvorskim(koncentracije uranijuma su reda veli~ine  10 mBq/L). Koncentracije prisutnihradionuklida, 238U, 234U, 232Th, 230Th, 228Th, 228Ra i 226Ra, su odre|ena alfa i gamaspektrometrijski. Kao indikacija radioaktivne neravnote`e u oba niza (238U, 232Th) izra-NATURAL RADIOACTIVITY OF WATERS FROM CENTRAL BALKAN 627~unati su i diskutovani slede}i odnosi: 234U/238U, 226Ra/230Th, 228Th/232Th, 228Ra/228Th. Uuzorcima izvorskih voda sadr`aj radijumovih izotopa je iznad ravnote`ne vrednostikoja se o~ekuje na osnovu sadr`aja roditeqskih nuklida.(Primqeno 14. maja, revidirano 28. juna 2006)REFERENCES1. Guidelines for Drinking Water Quality (2nd Edition, Vol. 1, 4.1.3. Recommedations), WHO(World Health Organization), Geneva, 19962. C. Kralik, M. Friedrich, F. Vojin, J. Environ. Radioac. 65 (2003) 2333. T. Kovacs, E. Bodrogi, P. Dombovari, J. Somlai, C. Nemeth, A. Capote, S. Tarjan, RadiationProtection Dosimetry 108 (2004) 1754. A. Martin Sancehz, M. P. Rubio Montero, V. Gomez Esobar, M. Jurado Vargas, Appl. Radiat. Iso-topes 50 (1999) 10495. Sources effects and risks of ionizing radiation, UNSECAR, Report to the General Assembly,United Nations, New York, 19936. D. Proti}, Mineral and thermal waters in Serbia, Posebna izdanja, 17, Belgrade, 1995 (in Serbian)7. M. Radenkovi}, D. Vukovi}, V. [ipka, D. Todoriv}, J. Radioanal. Nucl. Chem. 208 (1996) 4678. R. Rusconi, M. Forte, G. Abbate, R. Gallini, G. Sgorbati, J. Radioanal. Nucl. Chem. 260 (2004) 4219. M. Ivanovich, S. Russel, Uranium Series Disquilibrium Applications to Environmental Prob-lems., Chalderon, Oxford, 198210. J. C. Cuttell, M. Ivanovich, J. H. Tellam, J. W. Loyd, Appl. Geochem. 3 (1998) 25511. J. B. Cowart, J. K. Osmond, Preceedings in isotope technique in groundwater hydrology II, In-ternational Atomic Energy Agency (IAEA), 1974, p. 13112. O. K. Hakam, A. Choukri, J. L. Reyss, M. Lferde, J. Environm. Rad., 57 (2001) 17513. J. Kronfeld, J. A. S. Adams, J. Hydrol. 22 (1974) 7714. Tieh-Chi Chu, Jeng-Jong Wang, J. Nucl. Radioanal. Sci. 1 (2000) 515. J. G. Zukin, D. E. Harmond, T. L. Ku, W. A. Elders, Geochim. Cosmochim. Acta 51 (1987) 171916. A. L. Herczeg, H. J. Simpson, R. F. Anderson, Chem. Geol. 72 (1988) 18117. C. Beaucaire, P. Toulhoat, Appl. Geochem. 2 (1987) 426.628 JOKSI], RADENKOVI] and MILJANI]NATURAL RADIOACTIVITY OF WATERS FROM CENTRAL BALKAN 625

Miljanic, Scepan S.

VinaR - Repository of the Vinča Institute of Nuclear Sciences

J. Serb. Chem. Soc. 72 (6) 621–628 (2007) UDC 553.76:626.812:663.646:543.4/.5(497)
JSCS–3594 Original scientific paper
Natural radioactivity of some spring and bottled mineral
waters from several central Balkan sites, as a way of
their characterization
JASMINKA D. JOKSI]1*, MIRJANA B. RADENKOVI]1 and []EPAN S. MILJANI]2
1Vin~a Institute of Nuclear Sciences, Radiation and Environmental Protection Laboratory, P. O.
Box 522, 11001 Belgrade, Serbia and 2University of Belgrade – Faculty of Physical Chemistry,
P. O. Box 137, 11001 Belgrade, (e-mail: jasnaj@vin.bg.ac.yu)
(Received 14 May, revised 28 June 2006)
Abstract: In this work, a study of the radioactive content of some spring and bottled
mineral waters originating from metamorphic rock areas was carried out. Ahigh content
of radium isotopes (226Ra, 228Ra), was found by radiometric analysis in the spring wa-
ters: Studenica (226Ra: 289 mBq/L), ^ibutkovica (226Ra: 92, 4 mBq/L, 228Ra: 610
mBq/L), and Crni Guber (226Ra: 120 mBq/L, 228Ra: 1170 mBq/L). On the other hand,
the radiochemical results showed a higher concentration of 238U in the bottled mineral
water samples (dissolved uranium concentrations were from 0.21 mBq/L, for "Ko-
paonik" to 71.5 mBq/L fo "Skadarska") than in the spring water samples (dissolved ura-
nium concentrations were very low  10 mBq/L). The concentrations of all the present
naturally occuring radionuclides: 238U, 234U, 232Th, 230Th, 228Th, 228Ra and 226Ra
were determined by alpha/gamma spectrometric analysis. The activity ratios 234U/238U,
226Ra/230Th and 228Th/232Th, 228Ra/228Th were calculated and are discussed as an indi-
cation of the radioactive disequilibrium in bothe the 238U and 232Th radioactive series.
The high contents of radium isotopes with respect to the equilibrium values expected
from the respective parents 232Th/(232Th series) and 230Th (238U series) found in the
spring water samples is the main evidence for the existence of significant radioactive
disequilibrium in both the radioactive series.
Keywords: radioactivity: spring waters, mineral bottled waters, spectometry analy-
sis, radioactive equilibirum, activity rations.
INTRODUCTION
Due to the importance of drinking water for human life and the increased con-
sumption of mineral waters, their quality must be carefully and systematically con-
trolled. The recommended control of radioactivity levels in existing or new drink-
ing water includes total alpha/beta activity measurements, as an indication of po-
tentially enhanced radioactivity. In order to guarantee an exposure lower than 0.1
621
doi: 10.2298/JSC0706621J
* Corresponding author.
mSv/y, radioactivity levels for drinking water, recommended by the WHO (World
Health Organization), are 0.1 Bq/L for the gross alpha and 1 Bq/L for the gross beta
activity. The guideline levels are calculated using a water consumption rate of 2 L
daily. For natural mineral waters, the measurement on the naturally occurring
radionuclide 40K, which makes up about 0.12 % of natural potassium, is obligatory.1
If the gross alpha and/or gross beta activity exceed the recommended values of
0.1 Bq/L and 1 Bq/L, respectively, the contents of specific radionuclides have to be
determined by alpha and/or gamma spectrometric measurements.
During routine analysis of water samples mainly from Serbia, only a few samples
of spring waters were found to be above the limits of 1Bq/L for beta and 0.1 Bq/L for
alpha activity. These are the waters from Serbia (Studenica, ^ibutkovica) and one from
Bosnia and Herzegovina (Crni Guber). The distribution of naturally occurring radi-
onuclides 238U, 234U, 232Th, 230Th, 228Th, 228Ra and 226Ra in these waters, obtained
by spectrometric analysis, gave evidence of very interesting cases of disequilibrium of
radioactive series in the 238U and 232Th decay chains. Since the consumption of spring
and mineral waters is continuously growing in most regions in Europe, the monitoring
of the radioactivity of drinking water is becoming more important.2–4 Knowledge of
the concentrations of uranium and radium in drinking water is important because an
appreciable fraction of the absorbed uranium and radium is deposited in bones, with a
corresponding contribution to the internal dose.5
The objective of this study was to determine the concentrations of natural
radionuclides in some spring and some bottled mineral waters, and to compare
them with other studies conducted in the region and to discuss the obtained radio-
activity ratios 234U/238U, 226Ra/230Th and 228 Th/232Th, 228Ra/228Th.
EXPERIMENTAL
Spring water samples were taken at the locations of Studeni~ki izvori and Lazarevac (Serbia)
and Srebrenica (Bosnia and Herzegovina). A map of the sampling sites is shown in Fig. 1.
Spring water samples of 10 L were first acidified to pH 2 and then preconcentrated by evapora-
tion under an infrared light to about 450 mL (Table I).6
TABLE I. Characteristics of the spring mineral waters
Name Location Type of water Geological setting of aquifer
Studeni~ki izvori Studeni~ka reka, Studenica HCO3–Na Various schists
^ibutkovica Reka Grabovica, Lazarevac HCO3–Na Limestone crystalline schiests
Crni Guber Srebrenica HCO3–Na Bauxite
The studied commercially available bottled natural mineral waters are summarized in Table II,
together with some basic data on the aquifers. Water samples(8–12L) are acidified to pH 2 and
preconcentrated by evaporation under an infrared light to 450 mL.
After preconcentration, all water samples were sealed into Marrineli beakers and left for 28
days to reach the radioactive equilibrium betweeen 226Ra and daughters (214Bi and 214Pb). Gam-
ma-spectrometric measurements were performed using a HPGe Canberra detector with a counting
efficiency of 23 %. The activity of 228Ra was determined indirectly from its daughter, the 228Ac iso-
622 JOKSI], RADENKOVI] and MILJANI]
tope (338.4 keV and 911.2 keV energies). The radium isotope 226Ra was determined from its daugh-
ters 214Pb (295.1 keV and 351.9 keV) and 214Bi (609.3 keV, 1120.3 keV and 1764.5 keV). The 40K
activity was determined from the 1460.8 keV energy line.
TABLE II. Characteristics of the Serbian bottled mineral waters
Trade name Location Under-ground
depth/m
Type of water Geological settings of
aquifer
"Mivela" Velu}e 90–120 HCO3–Na,Mg Various schists
"Karadjordje" Smederevska Palanka 10–12 HCO3–Na,Mg,Ca Limestone crystalline
schists
"Kopaonik" Brus 700 HCO3–Na Limestone,vulcanites
"Prolom: Prolom Spa 200 HCO3–Na Vulcanites
"Skadarska" Skadarlija Brewery 61 HCO3,SO4–Ca,Mg Karstified limes
"Heba" Bujanovac Spa 200 HCO3–Na Crystalline schists
The preparation of thin-layer radioactive sources for alpha-spectrometric analysis included the
prior radiochemical procedure of separation of uranium and thorium from the sample matrix and puri-
fication from each other and finally electroplating onto stainless steel discs.7 Low-level activity mea-
surements were performed using a Canbera alpha-spectrometry counting system, consisting of a vac-
uum chamber (20 mbar), PIPS-detector (300 mm2 surface), with a counting efficiency of 15 % at a dis-
tance of 25 mm, a multichannel energy scale of 9.1 keV/ch and a resolution of 24 keV for 241Am.
The water samples were pretreated by evaporating to dryness and ashing with NaNO2, at 550
°C. After precipitation of the hydroxides, the ion-exchange extraction of uranium and thorium from
the matrix and separation and fractionation was performed using a DOWEX 14 (100–200 mesh)
chloride-conditioned resin. A further eluation on the ion-exchange resin was required for the purifi-
cation of the obtained uranium and thorium fractions. After extraction of iron, thin-layer radioactive
sources for alpha-spectrometry measurements were obtained from the uranium fraction by the
NATURAL RADIOACTIVITY OF WATERS FROM CENTRAL BALKAN 623
Fig. 1. Map of Serbia and its vicinity; location of
the investigated water resources are marked.
Talvities electroplating procedure. The talvities procedure was also employed for the thorium frac-
tion but the obtained sources had to be covered by VINS foil before measurements to prevent detec-
tor contamination by recoil.
To obtain the radiochemical yield 232U and 229Th standard tracer solution (Harwell Labora-
tory, UKAEA, England) were added to each sample.
RESULTS AND DISCUSSION
The gross alpha and beta activaties of the analyzed bottled mineral waters
were within the recommended values, except for the "Heba" and "Karadjordje"
samples, where the beta activities were enhanced due to the 40K concentration of
1530 and 2800 mBq/L, respectively. The high values of the total alpha and total
beta activities found in three of the examined natural spring water originating from
the metamorphic rock area, having a similar chemical compositions (carbon-acid),
are due to the high content of naturally occuring radionuclides of the 238U and
232Th series. The contect of racionuclides in bottled and spring mineral waters ob-
tained by alpha and gamma spectrometry are summarized in Table III.
It can be seen that the 238U and 234U isotope concentrations in the bottled waters
(dissolved uranium concentrations were very low  10 mBq/L) are higher than in the
samples of spring water (dissolved uranium concentrations range from 0.21 mBq/L
for "Kopaonik" to 71.5 mBq/L for "Skadarska"). These uranium concentrations are
comparable with some others from the region.3,4 They are even lower than those in
624 JOKSI], RADENKOVI] and MILJANI]
Fig. 2. a) Total urani-
um content (ppm) and
b) 234U/238U activity
ratio in the measured
mineral bottled and
spring waters.
T
A
B
L
E
II
I.
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ct
iv
it
ie
s
(m
B
q
/L
)
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r
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le
U
-2
3
8
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-2
3
4
U
-2
3
5
T
h
-2
3
2
T
h
-2
3
0
T
h
-2
2
8
R
a-
2
2
8
R
a-
2
2
6
K
-4
0
"M
iv
el
a"
0
.2
9
±
0
.0
6
0
.2
1
±
0
.0
7
<
0
.0
2
<
0
.8
6
<
0
.8
6
1
4
±
5
<
3
<
2
6
1
5
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±
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6
"K
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ad
jo
rd
je
"
7
.6
1
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.0
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.0
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±
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.7
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±
0
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1
<
0
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<
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5
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o
p
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ro
lo
m
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9
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M
3
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"S
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.4
±
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eb
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.0
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±
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±
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rn
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.3
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±
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<
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ib
u
tk
o
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ic
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<
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±
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.3
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.4
±
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8
.9
±
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.0
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±
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2
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±
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1
6
7
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±
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2
0
some bottled waters from Northen Italy.8 The 234U/238U activity ratio values in the
bottled samples were within the range from 0.6–3.3, which is in accordance with the
reported results.8,9 However, the low content of 238U in the "Heba" (0.22 mBq/L)
and "Prolom" (9.38 mBq/L) samples corresponds to a 234U/238U ratio greater than 1
(2 and 3.3, respectively), Fig. 2. The 234U excess compared to the 238U content in
waters may be explained by in situ leaching through alpha-recoil tracks.10 The same
correlation in well waters was attributed to the changes in the oxidizing/reducing
conditions of the aquifer environment,11 being characteristic in oxidizing zones.12
Elevated temperatures and strong reducing conditions usually result in the opposite
relations, due to the acceleration of isotope exchange processes.13
The 234U/238U ratios obtained for the spring waters Crni Guber, Studenica and
^ibutkovica were 1.22, 0.95 and 1.24, respectively, indicating the 238U series ra-
dioactive equilibrium.
The content of 226Ra and 228Ra isotopes, originating from the 238U and 232Th
decay series, was quite low in the analyzed bottled mineral waters, compared to the
values obtained for other bottled mineral waters3,4 and the investigated spring wa-
ters (Crni Guber, Studenica and ^ibutkovica).
The spring water samples were poor in uranium and rich in radium. The highest
concentrations of the Ra isotopes were found in the limestone regions, where Ra is
more soluble in HCO3
– waters.9 The values obtained show that a large a amount of
226Ra does not necessarily indicate a high 238U content, since the radium may migrate
and be deposited randomly from the surrounding rock areas.14 In geothermal sources,
where the temperature is high and the concentration of chlorine elevated and the reduc-
ing potential is very weak, the 226Ra/238U ratios are often high,15 even in the order of
103–104.16 In a reducing medium, with uranium less mobile than radium, the disap-
pearance of sulphates allows high radium concentrations in solution.17
The high content of radium isotopes with rescept to the equilibrium values, ex-
pected from the parent isotopes 232Th(232Th series) and 230Th(238U series), found
in the spring water samples, are evidence of the existence of a significant radioac-
tive disequililbrium in both radioactive series.
The 226Ra concentration in the spring mineral waters, exceeding the equilib-
rium value corresponding to the 230Th content, with 226Ra/230Th ratios of 38.5 and
6514 (Table IV), for the ^ibutkovica and Studenica samples, respectively, show a
significant of disequilibrium level of the 238U series.
TABLE IV. Radioactivity ratios of radionuclides from the 238U and 232Th series in the spring water
samples
Mineral water 234U/238U 226Ra/230Th 228Th/232Th 228Ra/228Th
Crni Guber 1.24 / 126.7 7.7
Studenica 1.24 6514 13.6 /
^ibutkovica 0.95 38.5 54.3 12.4
626 JOKSI], RADENKOVI] and MILJANI]
Considering the 232Th series, the 228Ra/228Th and 228Th/232Th ratios obtained
for the spring waters were much higher than expected from the amounts determined
for the parent isotopes (Table IV). The 228Ra excess in the waters may be attributed
to the different solubility of thorium and radium and a partly upward diffusion from
the surrounding sediments.9 In the decay process from 232Th to 228Th, the 228Ra
radionuclide (t1/2 = 5.75 y) is in the middle. Since the chemical properties of radium
and thorium are different, the high 228Th content derives from 228Ra.
CONCLUSION
Radiochemical analyses of some natural mineral bottled waters from several
locations in the central Balkan area showed the presence of naturally occurring
radionuclides from both the 238U and 232Th series. The relevant activity ratios
234U/238U, 226Ra/230Th, 228Th/232Th, 228Ra/228Th were indicative of radioactive
disequilibrium, especially in the spring water samples.
Higher 238U activities in some bottled, when compared with the examined
spring waters, show the reverse trend in the 238U activity versus the 234U/238U ac-
tivity ratio. The 238U and 234U isotope concentrations in the bottled waters were
found to be up to 71.5 mBq/L.The contents of 226Ra and 228Ra isotopes were quite
low and, in some cases below the detection limit.
The very high 226Ra and 228Ra activities in the spring waters do not necessar-
ily indicate high concentrations of their parents in the 238U and 232Th series.
The analyzed water samples are selected for analysis due to their enhanced
gross alpha/beta activity. The study gives a contribution to the radionuclides map-
ping of natural mineral waters in metamorphic petrology areas.
I Z V O D
PRIRODNA RADIOAKTIVNOST NEKIH IZVORSKIH I FLA[IRANIH
MINERALNIH VODA SA NEKOLIKO LOKACIJA NA CENTRALNOM
BALKANU, KAO NA^IN WIHOVE KARAKTERIZACIJE
JASMINKA D. JOKSI]
1
, MIRJANA B. RADENKOVI]
1
i []EPAN S. MIQANI]
2
1
Institut za nuklearne nauke Vin~a, Laboratorija za za{titu od zra~ewa i za{titu `ivotne sredine
"Za{tita", P. P. 522, 11001 Beograd i
2
Univerzitet u Beogradu – Fakultet za fizi~ku hemiju, P. P. 137,
11001 Beograd
U ovom radu su prikazani rezultati ispitivawa sadr`aja radionuklida u nekim
izvorskim i fla{iranim mineralnim vodama koji poti~u iz metamofrnih oblasti. U
izvorskim mineralnim vodama je izmeren visok sadr`aj radijumovih izotopa (226Ra,
228Ra): Studenica (226Ra: 2280 mBq/L), ^ibutkovica (226Ra: 92,4 mBq/L, 228Ra: 610 mBq/L) i
Crni Guber: (226Ra: 120 mBq/L, 228Ra: 1170 mBq/L). Sa druge strane, ve}a koncentracija
238U je detektovana u fla{iranim mineralnim vodama (koncentracije uranijuma se
kre}u od 0,21 mBq/L za "Kopaonik" do 71,5 mBq/L za "Skadarsku") nego u izvorskim
(koncentracije uranijuma su reda veli~ine  10 mBq/L). Koncentracije prisutnih
radionuklida, 238U, 234U, 232Th, 230Th, 228Th, 228Ra i 226Ra, su odre|ena alfa i gama
spektrometrijski. Kao indikacija radioaktivne neravnote`e u oba niza (238U, 232Th) izra-
NATURAL RADIOACTIVITY OF WATERS FROM CENTRAL BALKAN 627
~unati su i diskutovani slede}i odnosi: 234U/238U, 226Ra/230Th, 228Th/232Th, 228Ra/228Th. U
uzorcima izvorskih voda sadr`aj radijumovih izotopa je iznad ravnote`ne vrednosti
koja se o~ekuje na osnovu sadr`aja roditeqskih nuklida.
(Primqeno 14. maja, revidirano 28. juna 2006)
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628 JOKSI], RADENKOVI] and MILJANI]
NATURAL RADIOACTIVITY OF WATERS FROM CENTRAL BALKAN 625


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Natural radioactivity of some spring and bottled mineral waters from several central Balkan sites, as a way of their characterization

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