INSTITUTE FOR MEDICAL RESEARCH AND OCCUPATIONAL HEALTH Radiation Protection Unit

1. INSTITUTE FOR MEDICAL RESEARCH AND OCCUPATIONAL HEALTH Radiation Protection Unit 137Cs Inventory in South Adriatic Branko Petrinec, Ph. D. Glasgow, 2012.

2. Samples were collected during the “International Scientific Cruise to Adriatic and Ionian Seas”, 17-28 September 2007, organized under the International Atomic Energy Project (IAEA) regional TC project RER/7/003 “Marine Environmental Assessment of the Mediterranean Region”.

3. The Adriatic Sea is: • An epicontinental semi-enclosed sea • Forming a distinct sub-region within the Mediterranean region • It is a deeply indented gulf (cca 800 km long and 200 km wide) • Situated between the Apennine and Balkan peninsulas • The Croatian part of the Adriatic Sea consists of - 79 islands 525 islets - 642 rocks and rocks awash • The shallowest part of the Adriatic Sea is in the Gulf of Trieste, and its deepest part is in the South Adriatic Pit (1.233 m)

4. In this investigation, distribution of 137Cs through the middle and southern Adriatic Sea was determined in sediments and sea water collected on five locations.Its purpose was to better understand some of the key processes that influence the distribution of radionuclides in the topmost part of the sediment column, and to estimate sedimentation rates.

8. RADIONUCLIDES OF INTEREST • 137Cs  • 40K • Thorium • Uranium • Radium

10. Sampling locations

11. Sediments Shipek grab sampler: mass ≈50 kg designed to collect a volume of 3 L sample from a sampling area of about 20 cm x 20 cm used to collect soft, fine grained to sandy materials from any depth with even a sloping bottom Corer sampler: sampling tool for sediment columns of different diameters the box corer with the diameter of 10 cm penetration depth of 30 cm the column was sliced every 2 cm, acquiring 100 ml of dry sediment

14. Gammaspectrometry • A gamma ray spectrometry system, based on a High-Purity Germanium Coaxial Photon Detector System ORTEC HPGe detector (FWHM 2.24 keV at 1.33 MeV 60Co and relative efficiency of 74.2% at 1.33 MeV), coupled to a computerized data acquisition system was used to analyze collected samples. • The detector was shielded by 10 cm thick led well internally lined with 2 mm copper and 2 mm cadmium foils. • Energy and efficiency calibration of the gamma spectrometer were carried out using calibration sources supplied by Czech Metrological Institute covering energy range between 80 and 2500 keV.

15. Quality assurance, proficiency tests and intercalibration measurements were carried out throughout participation in international programs organized by International Atomic Energy Agency (IAEA), World Health Organization (WHO) and Joint Research Centre (JRC). • The testing method is accredited by the Croatian Accreditation Agency according to the ISO Norm 17025. • Before measurement, samples were dried and homogenized.

16. RESULTS • Total inventory of 137Cs in sea sediments in south Adriatic, which has an area of about 60,000 km2, has been estimated to be 2.32 E+15 Bq. • Total inventory of 137Cs in sea water in south Adriatic, which has a volume of about 28172 km3, has been estimated to be (8.51 ± 0.24) E+13 Bq. • The highest value of 137Cs activity concentration has been found on a sampling location in Albania (1.24 E+5 Bqm-2), while, for comparison, 137Cs activity concentration on the location Jabuka Pit in middle Adriatic was found to be 5.79 E+4 Bqm-2.

19. In-situ gammaspectrometry

20. In-situ gammaspectrometry has been performed by a High-Purity Germanium Coaxial Photon Detector System ORTEC HPGe detector, resolution 1,67 keV on 1,33 MeV 60Co and relative efficacy 22.6% on 1.33 MeV 60Co. • Coaxial detector has a vertical configuration and was set vertically downwards, 1 meter above the ground level. • The detector is connected with a multichannel analyzer and an associated computer data acquisition system. • Acquisition time was 5000 seconds • Software for analysis was GammaVision.

24. CONCLUSIONS • The dose rates were calculated and the radiologic risk was assessed for the middle-Adriatic islands • The concentrations of activity of all measured radionuclides are very similar along the coast of the Adriatic sea • The sedimentation rate (137Cs method) is very small • Mineralogic analysis indicated that the contents of the sediments is very similar on all localities • Granulometric analysis of the particle size did not show significant changes in the distribution of particle sizes according to depth on any localities except Palagruža • The results for organic matter in sediment (LOI) indicate that there is a very small presence of organic matter in sediment

25. CONCLUSIONS • 137Cs in the Adriatic Sea sediments originated mainly from fallout with significant contribution of runoff visible only on a sampling site in Albania • In undisturbed sediments collected in South Adriatic Pit, the deepest part of the Adriatic Sea, could be distinguished two 137Cs peaks, one from 1960s, i.e., from the period of intense atmospheric nuclear tests, the other being the Chornobyl peak • Regarding radioactive contamination by fission products, the Adriatic Sea is unpolluted • Investigations of 137Cs activity concentrations in Adriatic marine environment is an important part of an overall monitoring programme and is conducted in accordance with the European Commission Recommendation from June 8, 2000.

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