226Ra u pitkoj vodi Hrvatske

Owing to its exceptional radiotoxicity 226Ra in drinking water may directly affect human health. Its presence was investigated in several categories of drinking water in Croatia: well water, tap water from several municipal water supply systems and bottled mineral water. The method of 226Ra determination was alpha-spectrometric measurement after radiochemical separation. The 226Ra content in all investigated categories of waters are below the legislative level permissible for human health.Zbog svoje izuzetne radiotoksičnosti, 226Ra u pitkoj vodi može izravno utjecati na ljudsko zdravlje. U radu je opisano istraživanje specifične aktivnosti 226Ra u pitkoj vodi Hrvatske, i to: u uzorcima bunarskih voda, uzorcima vodovodnih voda u nekoliko gradova Hrvatske i u mineralnim vodama. 226Ra je određen alfa-spektrometrijskim mjerenjem nakon radiokemijske separacije. Istraživanje je pokazalo da je količina 226Ra u svim ispitivanim kategorijama voda ispod razine koju zakonska regulative smatra tolerantnom po zdravlje čovjeka

Radioactive Waste Due to Electric Power and Mineral Fertiliser Production

Istraživanja prirodne radioaktivnosti uz poznate izvore zagađenja, bilo da se radi o prirodno povišenoj radioaktivnosti određenog područja ili o tehnološki povišenoj prirodnoj radioaktivnosti, provode se već nekoliko desetljeća u Jedinici za zaštitu od zračenja Instituta za medicinska istraživanja i medicinu rada u Zagrebu. Saznanja o tehnološki povišenoj prirodnoj radioaktivnosti omogućila su dosadašnja istraživanja radioaktivnosti u blizini termoelektrana na ugljen i tvornice mineralnih gnojiva. Svi ugljeni i fosfatne rude sadržavaju prirodnu radioaktivnost, članove uranova i torijeva prirodnoga radioaktivnog niza. Iskorištavanjem tih sirovina, ugljeni u termoelektrani i fosfatne rude u proizvodnji mineralnih gnojiva koncentriraju u sebi sadržanu radioaktivnost u čvrstom ostatku procesa kojemu su podvrgnute. Posljedično je koncentracija prirodnih radionuklida u otpadu nekoliko puta veća nego što su koncentracije prirodnih radionuklida inače prisutnih u okolišu, osobito u okolnome tlu. Sav se otpad iz proizvodnje odlaže na odlagališta, ondje se gomila i prisutni prirodni radionuklidi zbog dugog vremena poluraspada (npr. 226Ra: T1/2=1600 godina) ostaju trajna prijetnja okolišu. Rezultati znanstvenih spoznaja iskorišteni su prilikom sanacije odlagališta pepela i šljake, a poslužili su i u izradi kriterija pri odabiru uvoznih sirovina. Izmjerene koncentracije prirodnih radionuklida uvoznih energetskih ugljena, koji se danas rabe u termoelektrani na ugljen, pokazuju povoljniji omjer prirodnih radionuklida tako da je sav otpadni pepeo podoban za uporabu u graditeljstvu odnosno u cementnoj industriji.Radiation Protection Unit of the Institute for Medical Research and Occupational Health in Zagreb has been conducting systematic investigations of radioactive contamination of the Croatian environment by anthropogenic fission products as well as by naturally occurring radioactive material (NORM) since 1963. Several critical sites in Croatia were identified for NORM, that is, for slag and ash repositories from coalfired power plants and phosphogypsum repository from a mineral fertilizer production plant. As the coals and phosphate ores contain naturally occurring radionuclides, especially the members of the uranium and thorium radioactive chains, utilising these materials in various industries only enhances their natural radioactivity in residual waste. Consequently, the resulting activity concentrations of natural radionuclides in waste material could be several times higher than in the adjacent soil. These deposited materials pose permanent risk of radiation exposure due to the long physical half-life of natural radionuclides (e.g., T1/2= 1600 years for 226Ra). Results of scientific investigations related to natural radioactivity are used in the recovery of slag and ash repositories and landfills, as well as in establishing regulatory criteria targeting import of coal and phosphate ores. In consequence, recently measured activity concentrations of natural radioactivity in imported materials used nowadays in coal-fired power plants are significantly lower than in previously used raw materials. Therefore, slag and ash can be used as additive materials in cement productio

Mosses and Some Mushroom Species as Bioindicators of Radiocaesium Contamination and Risk Assessment

Mosses, lichens, mushrooms are able to efficiently accumulate different radioactive elements from their environment to a much higher degree than other vegetation. They are sensitive bioindicators of radioactive contamination for various ecosystems, particularly in the event of a nuclear accident and uncontrolled emission oh fission products. Results of systematic, long-term measurements of 137Cs activities in mosses and in some edible mushroom species in North Croatia for the post-Chernobyl period (1986–2007) are summarized. The study was conducted in the Radiation Protection Unit of the Institute for Medical Research and Occupational Health in Zagreb, as a part of an extensive monitoring program of the Croatian environment. In the overall observed period the highest activity concentration of 137Cs deposited by fallout has been recorded in 1986, which is the year of Chernobyl accident, causing peak 137Cs activity concentration in moss of 8800 Bq/kg in May 1986. In the same period mean 137Cs activity concentration in grass was 390 Bq/kg. The highest value of 137Cs activity concentration in Cortinarius caperatus mushrooms of 1351 Bq/kg has been recorded in 1989. Fitting the measured 137Cs activity concentrations to the theoretical curve the ecological half-life of 137Cs in moss was found to be around 978 days, in grass around 126 days in the period 1986–1990, in Cortinarius caperatus mushroom around 5865 days (16.1 years). Regarding the risk assessment to Croatian population, due to consumption of mushrooms, the collective effective dose for Croatian population, estimated to be about 35 mSv per year, was found to be quite low. Therefore, it can be concluded that mushroom consumption was not a critical pathway for the transfer of radiocaesium from fallout to humans after the Chernobyl accident

226Ra and 228Ra in Croatian Rivers

The presence of natural radionuclides in Croatian rivers emphasizes the need for its continuous monitoring. Therefore results of 226Ra and 228Ra determination in Croatian river waters are presented in this paper. 226Ra and 228Ra were chosen as a possible source of human exposure due to their high radio-toxicity. Fifty liters of river water samples were collected from the Danube, Drava, Sava, Krka and Neretva rivers twice a year from 2002 to 2006. It is showed that activity concentrations of 226Ra ranged from 6.54 mBq/L to 59.44 mBq/L and 228Ra activity concentrations ranged from 2.57 mBq/L to 20.76 mBq/L. The highest values of both 226Ra and 228Ra were measured in the river Drava, and the lowest values in the river Sava. Statistically significant differences were not observed between radium concentrations from two watersheds (the Black Sea and the Adriatic Sea watershed), nor between 226Ra/228Ra ratio in rivers individually. The number of collected samples is insufficient to make more statistically significant conclusions. However the data obtained in this study could be the baseline for evaluating possible future changes

Current Exposure of Croatian Population to Ionising Radiation

Od vremena otkrića radioaktivnosti i postepenog ovladavanja i iskorištavanja pojava vezanih uz radioaktivnost razvijala se i ideja o potrebi zaštite od ionizirajućeg zračenja. Zaštita od zračenja razvila se u sustavnu djelatnost, a danas je to razvijena doktrina i znanstvena disciplina koja holističkim pristupom vodi brigu o zračenju, o ljudima izloženima zračenju, ali istodobno i o ljudskom okruženju i o okolini. Razvojni trendovi znanosti o zračenju, zaštite od zračenja i tehnološkog područja koje se njima bavi, neprestano unose nove sastavnice u doktrinu zaštite od zračenja, što novim preporukama dovodi do minimiziranja izlaganja zračenju. Radiološke nesreće dodatno senzibiliziraju ljude na opasnosti od ionizirajućeg zračenja. Nuklearne nesreće, kao ona u Černobilu 1986. godine, postavljaju pred cjelokupnu zajednicu pitanja o granicama doza ionizirajućeg zračenja, kako na lokalnoj tako i na međunarodnoj razini. Svakodnevni intenzivni promet robe, ljudi i usluga dodatno otkriva probleme vezane uz ograničavanja koja su nužna u slučaju mogućih nuklearnih nesreća većih razmjera. No, istodobno postavlja se pitanje i o uspostavi i održavanju jednako vrijednih standarda radiološke zaštite. Brojnim propisima i preporukama pokušava se urediti život i djelatnost ljudi u stvarnom životnom okruženju na način da se minimiziraju rizici i očuva radiološka čistoća habitata. Institut za medicinska istraživanja i medicinu rada iz Zagreba (IMI) ovlašten je za obavljanje stručnih poslova zaštite od ionizirajućeg zračenja. Suradnici Jedinice za zaštitu od zračenja IMI različitim analitičkim metodama određuju aktivnost bilo kojeg radionuklida u bilo kojem uzorku, kao i doze ionizirajućeg zračenja u bilo kojoj točki prostora. Tako npr. provode gamaspektrometrijske analize uzoraka za utvrđivanje koncentracije aktivnosti radiocezija u uzorcima namirnica, kao i u uzorcima predmeta opće uporabe namijenjenim izvozu ili onih uvezenih u Hrvatsku. Izdaju se mišljenja - certifi kati u kojima se poziva na preporuke i mišljenje Europske zajednice, kao i na nacionalnu legislativu.In theory, limits of radioactive contamination of food should be based on risk analysis, but in practice this procedure is compromised by economic reasons. This paper looks into the EU limits for radiocaesium in foodstuffs after the Chornobyl accident and gives a few examples of effective dose assessment of 137Cs. Croatia has harmonised radiation protection regulations with international and EU standards. This article presents the effective doses in the adult population of Croatia assessed at the Radiation Protection Unit of the Institute for Medical Research and Occupational Health. The assessment included ingestion, inhalation, and external exposure, and distinguished between radionuclide intake through food, water, and injection in medical procedures. Our results show low 137Cs activity concentrations, which are within limits, even though the radiation standards are very stringent. Therefore, their contribution to the effective dose is very small (<0.1 mSv)

Radioaktivnost tla u Hrvatskoj I. – prirodnopojavni lanci raspada

The assessment of environmental radioactivity much relies on radionuclide content in soil. This stems from the significant contribution of soil to both external and internal exposure to ionising radiation via direct emission of gamma radiation and soil-to-plant radionuclide transfer, respectively. This motivated us to carry out a systematic research on the radioactivity of soil in Croatia to obtain relevant data that can be used as a basis for understanding the related effects of geomorphological, biogeographical, and climatological properties of the environment. We collected samples of the surface layer of uncultivated soil (0–10 cm) at 138 sites from all over the country and measured them for radionuclide activity concentrations by means of high-resolution gamma-ray spectrometry. This resulted in radioactivity maps containing data on activity concentrations of representative radionuclides in the environment. In this paper, which is the first in our two-part presentation, we focus on the naturally occurring 232Th and 238U decay chains and their correlations with the diversity of Croatian regions. For both of the chains, activity concentrations were the highest in the Dinaric region, the lowest in the Pannonian region, and intermediate in the Adriatic region. Relatively high concentrations of 226Ra in the soil of the Dinaric region implied a possibility of an enhanced emanation of its progeny 222Rn into the air. Activity concentrations of 210Pb were additionally elevated in areas with dense vegetation, most probably due to an atmospheric deposition of airborne 210Pb onto the surface of plants and their eventual decomposition on the ground.U radioaktivnosti okoliša velika se pažnja posvećuje radionuklidima u tlu. Taj interes slijedi iz značajnih doprinosa tla I vanjske i unutarnje izloženosti ionizirajućem zračenju izravnom emisijom gama-zračenja i transferom radionuklida iz tla u biljke. To nas je motiviralo da provedemo sustavno istraživanje radioaktivnosti tla u Hrvatskoj kako bismo dobili relevantne podatke kao osnovu za razumijevanje pripadnih učinaka geomorfoloških, biogeografskih i klimatoloških svojstava okoliša. Prikupili smo uzorke površinskoga sloja (0–10 cm) nekultiviranoga tla s 138 lokacija diljem zemlje te smo mjerili koncentracije aktivnosti u njima koristeći se visokorezolucijskom gamaspektrometrijom. To je rezultiralo mapama radioaktivnosti hrvatskoga tla, koje sadržavaju podatke o koncentracijama aktivnosti reprezentativnih radionuklida u okolišu. U ovom radu, koji je prvi u našoj dvodijelnoj prezentaciji, fokusirali smo se na prirodnopojavne 232Th i 238U lance raspada i njihove korelacije s raznolikošću hrvatskih regija. Za oba su lanca koncentracije aktivnosti bile najviše u dinarskom području, najniže u panonskom području i srednje u jadranskom području. Posebice, relativno visoke koncentracije 226Ra u tlu dinarskoga područja impliciraju mogućnost povišene emanacije njegova potomka 222Rn u zrak. Koncentracije aktivnosti 210Pb bile su dodatno povišene u područjima s gustom vegetacijom, vrlo vjerojatno zbog atmosferske depozicije iz zraka na biljke te na njihovu konačnu dekompoziciju na tlu

Radioaktivnost tla u Hrvatskoj II.: 137Cs, 40K i brzina apsorbirane doze

We took samples of uncultivated soil from the surface layer (0–10 cm) at 138 sites from all over Croatia and measured their radionuclide activity concentrations with high-resolution gamma-ray spectrometry. This second part of our report brings the results on 40K and 137Cs to complement those on the 232Th and 238U decay chains addressed in the first part. Together they give the most complete picture of radioactivity of Croatian soil so far. Activity concentrations of 40K were the highest in the Pannonian region, and there was an opposite trend for 137Cs. We found that the concentrations of 137Cs tended to increase with altitude, annual precipitation, and vegetation density. The concentration ratio of 137Cs and K in soil, which indicates the potential for 137Cs entering food chains via uptake by plants, was the lowest in agriculturally important areas in the east of the Pannonian region. In addition, we used the obtained results on activity concentrations to calculate the related absorbed dose rate as a measure of external exposure to ionising radiation from soil. The sum of the absorbed dose rates for naturally occurring radionuclides and 137Cs showed that external exposure was generally the highest in the Dinaric region and Istrian Peninsula.Uzorkovali smo površinski sloj (0–10 cm) nekultiviranog tla na 138 mjesta diljem Hrvatske i mjerili koncentracije aktivnosti radionuklida u prikupljenim uzorcima visokorezolucijskom gamaspektrometrijom. U ovom radu, koji je drugi dio naše dvodijelne prezentacije, fokus je na 40K, 137Cs i brzini apsorbirane doze zbog prisutnosti radionuklida u tlu. Ti rezultati dopunjuju one vezane uz 232Th i 238U lance raspada, što vodi do dosad najcjelovitije slike radioaktivnosti tla u Hrvatskoj. Koncentracije aktivnosti 40K bile su najviše u hrvatskom panonskom području, a trend za 137Cs bio je suprotan. Našli smo da su koncentracije 137Cs pokazivale tendenciju porasta s nadmorskom visinom, količinom oborine i gustoćom vegetacije. Omjer koncentracija 137Cs i K u tlu, a koji predstavlja potencijal za ulaz 137Cs u hranidbene lance apsorpcijom putem biljaka, bio je najmanji na istoku panonskoga područja gdje se nalaze poljoprivredno važne površine. Rezultate za koncentracije aktivnosti iskoristili smo za izračun posljedične brzine apsorbirane doze kao mjere vanjske izloženosti ionizirajućem zračenju iz tla. Zbroj brzina apsorbirane doze za prirodnopojavne radionuklide i 137Cs pokazao je da je vanjska izloženost općenito bila najveća u dinarskom području i na istarskom poluotoku