Search

Grad Zagreb leži na šljunkovitim aluvijalnim nanosima rijeke Save koje sadrže velike količine prirodno profiltrirane podzemne vode. Voda se crpi na 7 vodocrpilišta iz 30 zdenaca. Na području PP Medvednica nalazi se 8 vodospremnika koji opslužuju gornje vodoopskrbne zone Grada Zagreba. Institut za medicinska istraživanja i medicinu rada, smješten nizvodno od Medvednice, provodi sustavno mjerenje koncentracija aktivnosti 137Cs u vodovodnoj vodi. U ovom radu bit će prikazani rezultati praćenja stanja koncentracija aktivnosti 137Cs tijekom višegodišnjeg perioda uzorkovanja (od Černobilske nesreće do danas), kao i izračun efektivne doze na čovjeka koja je posljedica konzumacije vodovodne vode Grada Zagreba. Uzorci su mjereni metodom visokorezolucijske gamaspektrometrije u energijskom rasponu 40 – 2000 keV koja je od 2010. godine akreditirana od Hrvatske akreditacijske agencije sukladno Normi HRN EN ISO/IEC 17025. Koncentracije aktivnosti 137Cs u vodovodnoj vodi kretale su se od 17, 68 ± 6, 61 Bqm-3 u 1987. godini (godina nakon nuklearne nesreće u Černobilu) do 0, 27 ± 0, 03 Bqm-3 u 2018. godini, dok su koncentracije aktivnosti u 2019. i 2020. godini bile ispod granice detekcije. Efektivna doza na čovjeka (procjena za konzumaciju 730 L godišnje) kretala se od 0, 28 μSv u 1987. godini do 2.5 nSv u 2018. godini. Ukupna efektivna doza na čovjeka u tom periodu iznosila je

Kontaminacija ekosustava umjetno stvorenim radionuklidima događa se već desetljećima. Ispušteni radionuklidi (posljedica testiranja nuklearnog oružja i nuklearnih nesreća) vežu se na veće molekule i čestice koje se nalaze u zraku. Na njihovo rasprostiranje bitno utječu meteorološki parametri kao što su vjetar i oborine. Uz zrak i tlo, oborine su jedan od prvih pokazatelja kontaminacije u atmosferi. Radionuklidi kao što su 137Cs i 90Sr duže vrijeme se nalaze u okolišu zbog relativno dugog vremena poluraspada i potencijalni su izvor kontaminacije biote. Oborine se svakodnevno, u dane s oborinama, sakupljaju na lokaciji Instituta. Dnevni se uzorci spajaju u zbrojni tromjesečni koji se nakon toga uparava na volumen 1 L. Koncentracije aktivnosti 137Cs izmjerene su gamaspektrometrijskim sustavom koji se temelji na ORTEC HPGe detektoru (FWHM 2, 24 keV na 1, 33 MeV 60Co s relativnom efikasnošću od 74, 2 % na 1, 33 MeV 60Co), spojenim s višekanalnim analizatorom. Za radiokemijsku analizu koncentracije aktivnosti 90Sr, uzorak je uparen do suhog. Standardnom metodom ekstrakcije s tributil fosfatom uz dodatak itrijevog nosača ekstrahiramo 90Sr temeljem radioaktivne ravnoteže s 90Y. Uzorci su mjereni u antikoincidentnom beta brojaču niskog osnovnog zračenja model RISØ GM-25-5. Metode su akreditirane prema zahtjevima norme HRN EN ISO / IEC 17025. Vrijednosti koncentracije aktivnosti 137Cs u oborinama za 2020. godinu se kreću u rasponu od 0, 52 Bq m-3 do 3, 15 Bq m-3. Srednja vrijednost je 1, 3 Bq m-3. Vrijednosti koncentracije aktivnosti 90Sr u oborinama za 2020. godinu se kreću u rasponu od 0, 06 Bq m-3 do 3, 78 Bq m-3. Srednja vrijednost koncentracije aktivnosti 137Cs iznosi 1, 3 Bq m-3, dok srednja vrijednost koncentracije aktivnosti 90Sr iznosi 1, 19 Bq m-3. Srednja vrijednost koncentracije aktivnosti 137Cs izražena po m2 pale oborine za 2020. godinu iznosi 0, 21 Bq m-2, dok za 90Sr iznosi 0, 14 Bq m- 2. Izmjerene koncentracije aktivnosti ne odstupaju značajno od izmjerenih vrijednosti prethodnih nekoliko godina. U radu je prikazan jedan dio sustavnih radioloških istraživanja koja Jedinica za zaštitu od zračenja Instituta za medicinska istraživanja i medicinu rada provodi na području Republike Hrvatske.

Prirodni i antropogeni radionuklidi prisutni su u našoj životnoj sredini. Prisutnost umjetno stvorenih radionuklida u okolišu posljedica je raznih događaja kao što su npr. nuklearna testiranja, te nuklearne i radiološke nesreće. Zbog toga se radionuklidi poput 137Cs i 90Sr mogu pronaći i u raznim namirnicama, uključujući mlijeko. Prisutnost tih radionuklida u mlijeku može biti potencijalno opasno za ljudsko zdravlje zbog njihovih dugih vremena poluraspada (T1 / 2 137Cs= 30, 17 god. ; T1 / 2 90Sr=28, 78 god.) te zbog njihove kemijske i metaboličke sličnosti s kalijem i kalcijem s kojima se lako zamijene u ljudskom organizmu. Za ljudsku prehranu najčešće se upotrebljava kravlje mlijeko koje predstavlja njen značajan dio. Ukoliko bi došlo do povećanih koncentracija aktivnosti 137Cs i 90Sr u toj namirnici ono bi predstavljalo značajan izvor kontaminacije radionuklidima putem hrane. U Jedinici za zaštitu od zračenja Instituta za medicinska istraživanja i medicinu rada godinama se provode istraživanja radioaktivnosti u okolišu. Između ostalog, u Jedinici se radiokemijskim metodama određuje aktivnost radionuklida u različitim uzorcima iz okoliša, uključujući mlijeko. Mlijeko se uzorkuje skupljanjem dnevnih uzoraka koji se zatim spajaju u zbirni dvomjesečni uzorak. Uzorak se zatim uparava pod infracrvenim žaruljama do suhog. Takav uzorak se spaljuje na otvorenom plamenu i zatim u peći na 450°C. U dobivenom pepelu određuje se koncentracija aktivnosti 137Cs gamaspektrometrijskom analizom. Za određivanje koncentracije aktivnosti 90Sr uzorak mlijeka spaljuje se na 650°C i radiokemijskom metodom ekstrakcije TBP-om uz dodatak itrij nosača određuje se koncentracija aktivnosti 90Sr kroz ravnotežu s 90Y koji se mjeri antikoincidentnim beta brojačem niskog osnovnog zračenja. Izmjerena prosječna vrijednost koncentracije aktivnosti 137Cs u mlijeku iz Pušće u 2020. godini iznosila je 27 mBq / L, a prosječna vrijednost koncentracije aktivnosti 90Sr iznosila je 21 mBq / L. Procijenjene efektivne doze zračenja odrasle populacije od unosa 137Cs i 90Sr mlijekom iz Pušće u 2020. godini iznosile su 35 μSv za 137Cs te 58 μSv za 90Sr i kao takve ne predstavljaju značajno opterećenje niti negativan utjecaj na ljudsko zdravlje.

The Radiation Protection Unit of the Institute for Medical Research and Occupational Health in Zagreb monitors activity concentrations of radionuclides in environmental samples in the Republic of Croatia. This paper presents the results of monitoring 90Sr in samples of lettuce, chard and cabbage, obtained in the period from 2013 to 2017 at two locations, in Zagreb and Zadar. Results for the samples of lettuce, cabbage, and chard vary within two orders of magnitude, ranging from 18.2 mBq kg-1 for lettuce to 341 mBq kg-1 for chard, both samples being collected in Zagreb. These differences can be explained by various factors like pH, organic and chemical properties of soil, different climatic conditions, etc. We calculated the annual effective doses from 90Sr intake by ingestion. The highest value of 146.79 nSv was estimated for 2015 for Zagreb, and the lowest, 54.16 nSv, for Zadar for the same year. Since the upper limit of public exposure is 1 mSv per year, we can conclude that the estimated doses are low and do not present a health hazard for the population living at these locations and consuming these types of vegetables. Certainly, the radiological condition of the environment and the influence of all related factors should be monitored, in order to detect changes and potential radiological contamination that in the future possibly could have adverse effects on human health.

Radioactivity measurements and monitoring of the human environment in Croatia are part of the monitoring programme carried out by the Radiation Protection Unit of the Institute for Medical Research and Occupational Health in Zagreb. Among other radionuclides and samples, this includes radiostrontium and radiocaesium in milk. The objective of this paper was to present and discuss the activity concentrations of 137Cs and 90Sr in milk collected in the Osijek region in five consecutive years (from 2011 to 2015). The 137Cs activity concentrations ranged from 0.08 Bqm-3 to 65.88 Bqm-3, except for May 2011 when an activity concentration of 900.62 Bqm-3 was measured. This high value contributed to a higher effective dose for 2011. The 90Sr activity concentration ranged from 14.56 Bqm-3 to 86.08 Bqm-3. The average activity concentration for each year and radionuclide was calculated and the effective doses received from milk consumption were estimated for the adult population of the Osijek region. The effective doses received from 137Cs uptake by milk consumption ranged from 4 nSv up to 168 nSv for 2011. This effective dose was one order of magnitude higher than the effective doses for the four other years. The effective doses received from 90Sr uptake by milk consumption ranged from 51 nSv to 119 nSv. Continuous control and monitoring of radioactivity in food and the environment are necessary to detect possible future changes in radioactivity levels in the environment. This will result in the protection of the population from the negative effects of ionizing radiation.

At the Institute for Medical Research and Occupational Health in Zagreb, Croatia, research on environmental radioactivity has been carried out over a number of years. After the Fukushima accident in March of 2011, we have paid a special attention to its possible impact on the radioactivity of soil and precipitation in Northwest Croatia (Zagreb region). Before and after the accident, we determined the activity concentrations of 137Cs (A) in soil samples taken from three adjacent surface layers (depths of 0-5 cm, 5-10 cm, and 10-15 cm) as well as in samples of milk. Before the accident, A in the soil was nearly uniform, only slightly increasing with increasing depth. Shortly after the accident, we observed an increase of A in the topmost layer, which was in agreement with the values of A measured in fallout. In subsequent years, we have detected both the penetration of 137Cs deeper into the soil and the overall decrease in A. In 2010, the values of A in milk were quite uniform over the months, amounting to about 35 Bqm-3. In 2011, this increased to 199 Bqm-3 in average, mainly due to the large values measured in the summer months ; we attribute this effect to the influx of the radioactive matter from Fukushima. In consequence of the increased presence of 137Cs, the estimated yearly effective dose due to the intake of 137Cs via milk in 2011 was 200 nSv, which can be compared with 73 nSv in the period of 2010-2015.

We report on a part of a study of the environmental radioactivity in the Plitvice Lakes National Park that was carried out during 2011 and 2012. This part was focused on measuring the activity concentrations of important naturally occurring ( 40 K, 7 Be, 238 U, 235 U, 232 Th, 226 Ra, 210 Pb) and fission produced ( 90 Sr, 134 Cs, 137 Cs) radionuclides in collected samples of selected living organisms, these being moss, lichen, pine needles, mushrooms, earthworms, and fish. Our results suggest that the radiological load on the local biota was within the limits characteristic of Croatia, exhibiting no indication of negative trends. Only in one moss sample, we found an elevated activity concentration of 137 Cs. Taking into account that a low level of radioactivity in inorganic matter from the same environment was found in this study as well, we can conclude that the Plitvice Lakes National Park is a clean area from the point of view of radioecology.

We report on a part of a study of the environmental radioactivity in the Plitvice Lakes National Park that was carried out during 2011 and 2012. This part was focused on measuring the activity concentrations of important naturally occurring ( 40 K, 7 Be, 238 U, 235 U, 232 Th, 226 Ra, 210 Pb) and fission produced ( 90 Sr, 134 Cs, 137 Cs) radionuclides in collected samples of soil, lake water, and river water, and also on determining the ambient dose equivalent rate H*(10)/t. Activity concentrations were determined by means of a high- resolution gamma ray spectrometry, except in the case of 90 Sr for which radiochemical separation and beta counting were used. The measured values of activity concentration were similar to those in other parts of continental Croatia. H*(10)/t was determined using continuously operating ALARA electronic dosimeters, and its value between April 2011 and October 2012 amounted to 77 ± 7 nSv/h. The only unusual feature we observed were large fluctuations of H*(10)/t in April 2011, which most likely occurred due to the Fukushima accident but did not last long.

A method for the rapid determination of radioactivity in cases of release into the environment as well as in cases of nuclear/radiological accidents is described. These measurements would enable a direct risk assessment for humans and biota, without any sampling and at a considerably larger number of locations than in previous studies. Thus obtained, the substantially expanded dataset is expected to shed more light on the properties of environmental radioactivity both in the region studied and in other similar areas. Field measurements will be performed and samples of soil and biota will be collected in order to compare field results with laboratory measurements. Once the method has been validated, previously unexplored locations will be included in the study. Our measurements at numerous locations will also provide control values for comparison in cases of any unplanned or accidental radiological event. An assessment of the possible effects of radionuclide concentrations on the human food chain and biota will be performed within the appropriate models used worldwide exactly for this purpose. In this way, the project should contribute to regional, European, and global efforts towards understanding the radiological impact on ecosystems. Field measurements will also address certain issues in the environmental metrology of radioactive substances, e.g., simultaneous determination of activity concentrations and related dose rates. This will serve as a tool for rapid risk assessment in emergency situations.

Nuklearne probe, radiološke nesreće te primjena nuklearne tehnologije u ljudskoj djelatnosti odgovorni su za prisutnost umjetnih radionuklida u okolišu, pa tako i u raznim namirnicama koje ulaze u hranidbeni lanac čovjeka. Mlijeko je vrlo zastupljena namirnica u prehrani čovjeka, a pogotovo djece. U slučaju povećanih koncentracija aktivnosti 137Cs i 90Sr u mlijeku, ono postaje značajan izvor kontaminacije putem hrane. U ovom radu prikazane su izmjerene koncentracije aktivnosti 137Cs i 90Sr u mlijeku zagrebačke regije u 2011. godini. Na temelju tih rezultata procijenjene su efektivne doze zračenja dobivene unosom 137Cs i 90Sr mlijekom za 2011. godinu. Iako procijenjene efektivne doze zračenja za odraslu populaciju zagrebačke regije ne predstavljaju značajno opterećenje, važno je neprekidno pratiti radioaktivnost u hrani i okolišu kako bi se stanovništvo zaštitilo od negativnih učinaka ionizirajućeg zračenja.

Two different procedures have been used for isolation of water-insoluble β-glucans from brewer’s yeast: alkaline-acidic isolation (AA) and alkaline-acidic isolation with mannoprotein removal (AAM). The obtained β-glucans were then dried by air-drying, lyophilization and combination of sonication and spray-drying. β-Glucan preparations obtained by AA and AAM isolations had similar values of dry mass, total polysaccharides, proteins and organic elemental microanalysis. The mass fractions of β-glucan in total polysaccharides were significantly affected by different isolation procedures. Fourier transform infra-red (FTIR) spectra of all preparations had the appearance typical for (1-3)-β-D-glucan. Lyophilization and especially air-drying caused a higher degree of agglomeration and changes in β-glucan microstructure. Sonication followed by spray-drying resulted in minimal structural changes and negligible formation of agglomerates.