RADIONUCLIDES IN THE ADRIATIC SEA AND RELATED DOSE-RATE ASSESSMENT FOR MARINE BIOTA Branko Petrinec 1, *, Marko S ˇ trok 2 , Zdenko Franic ´ 1 , Borut Smodis ˇ 2 and Dijana Pavic ˇic ´-Hamer 3 1 Institute for Medical Research and Occupational Health, Ksaverskacesta 2, HR-10001 Zagreb, Croatia 2 Joz ˇef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia 3 Center for Marine Research, Ruder Bos ˇkovic ´ Institute, G. Palliage 5, 52210Rovinj, Croatia *Corresponding author: petrinec@imi.hr Received February 17 2012, revised July 6 2012, accepted August 1 2012 Artificial and natural radionuclides were determined in the Adriatic Sea in the seawater and sediment samples in the period from 2007 to 2011. The sampling areas were coastal waters of Slovenia, Croatia and Albania, together with the deepest part of the Adriatic in South Adriatic Pit and Otranto strait. Sampling locations were chosen to take into account all major geo- logical and geographical features of this part of the Adriatic Sea and possible coastal influences. After initial sample prepar- ation steps, samples were measured bygamma-ray spectrometry. In the seawater 40 K activity concentrations were in the range from 6063 to 10519 Bq m 23 , 137 Cs from 1.6 to 3.8 Bq m 23 , 226 Ra from 23 to 31 Bq m 23 , 228 Ra from 1 to 25 Bq m 23 and 238 U from 64 to 490 Bq m 23 . The results of sediment samples showed that 40 K was in the range from 87 to 593 Bq kg 21 , 137 Cs from 0.8 to 7.3 Bq kg 21 , 226 Ra from 18 to 35 Bq kg 21 , 228 Ra from 4 to 29 Bq kg 21 and 238 U from 14 to 120 Bq kg 21 . In addition, the ERICA Assessment Tool was used for the assessment of dose rates for reference marine organisms using the activityconcentrations of the determined radionuclides in seawater. The assessment showed that for the most of the organisms, the dose rates werewithin the background levels, indicating that the determined values for seawater does not pose a significant risk for the most of marine biota. In the study, the results are critically discussed and compared with other similar studies worldwide. Generally, the activityconcentrations of the examined radionuclides did not differ from those reported for the rest of the Mediterranean Sea. INTRODUCTION The Adriatic Sea, being a semi-enclosed part of the Mediterranean Sea is, due to its geophysical charac- teristics, more sensible to any kind of pollution, in- cluding radioactive contamination. Consequently, marine radioecology investigations take a significant part in an extended and still ongoing monitoring programme of radioactive contamination of human environment in Croatia (1) , which also include dose assessment (2) . In addition, natural as well as an- thropogenic radionuclides are used as radioactive tracers helping to describe a number of various geo- physical, biochemical and other processes (3, 4) . The characteristics of the Adriatic Sea basin with special interest on the marine radioecology were in detail described previously (1) . Regarding this study, seawater sampling locations were chosen in such a way that they cover most important urban areas and industrial activities alongside Croatian and Slovenian coast, as well as geographical features, which could influence the radionuclide concentrations. First, the location lies close to a historical city of Dubrovnik and is not affected by any industrial activities. Ploc ˇe is a major international port with frequent cargo ship transport activities. This sampling location can be affected by those activities. On the other hand, Split is the largest coastal city in Croatia with ≏190 000 inhabitants with a lot of different ferry lines and in- dustrial activities. Consequently, this location can be affected by sewage wastewaters as well as with other industrial activities. The location in Kas ˇtela is situ- ated close to a slag and ash repository with elevated natural radionuclide concentrations and therefore it can be expected that the influence of that waste could also be found in seawater. The Novigrad Sea is abay, which is connected with the Adriatic Sea through a relatively narrow channel. There are no industrial ac- tivities, which could influence the levels of radionu- clides, but because of a specific geographic position and because of limited exchange with the outer sea, the radionuclides could be enhanced. Close to the sampling location in Rijeka there is, as in the case of Ploc ˇe, a major international port for cargo ships. In addition, Rijeka is the second largest coastal city in Croatia with ≏150 000 inhabitants. Close to Rijeka there is also oil refinery and other industrial activities. The location in Plomin is situated in ≏200 m broad and a 2-km long bay with a small port and a major coal fired power plant situated with the slag and a nearby slag ash repository. The location in Rovinj, which is touristic city with no large industrial activ- ities, is not expected to be subjected to any substan- tial influence from the coast. The same can be expected also for location close to Piran. On the # The Author 2012. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com Radiation Protection Dosimetry (2012), pp. 1–11 doi:10.1093/rpd/ncs234 Radiation Protection Dosimetry Advance Access published August 26, 2012 at Trent University on August 27, 2012 http://rpd.oxfordjournals.org/ Downloaded from