Levels of radionuclide concentrations in benthic invertebrate species from the Balearic Islands, Western Mediterranean, during 2012–2018

1 Levels of radionuclide concentrations in benthic invertebrate species from the Balearic 1 Islands, Western Mediterranean, during the period 2012–2018 2 3 Authors: Santiago Hurtado-Bermúdez *(1), José María Valencia (2), Jorge Rivera-Silva (1), 4 José Luis Mas (1, 3), Irene Aparicio (4), Juan Luis Santos (4), Esteban Alonso (1, 4) 5 6 7 (1) Servicio de Radioisótopos, Centro de Investigación, Tecnología e Innovación 8 (CITIUS), Universidad de Sevilla, Av. Reina Mercedes 4B, 41012 Sevilla, Spain 9 (2) Laboratori d'Investigacions Marines i Aqüicultura (LIMIA). Direcció General de 10 Pesca i Medi Marí. Illes Balears. Avda. Ingenyer Gabriel Roca, 69, 07157 Port d'Andratx, 11 Spain 12 (3) Departamento de Física Aplicada I, Escuela Universitaria Politécnica, Universidad de 13 Sevilla, Spain 14 (4) Departamento de Química Analítica, Escuela Politécnica Superior, Universidad de 15 Sevilla, C/ Virgen de África 7, 41011 Sevilla, Spain 16 17 18 19 20 21 22 Declarations of interest: none 23 24 25 26 27 28 29 30 31 32 * Corresponding author. +34-954559750. E-mail address: [email protected] 33 34 2 Abstract 35 36 Baseline levels of radionuclides in the marine environment of the Balearic Islands in the 37 Western Mediterranean are non-existent. Because of their ecological role and 38 acknowledged sensitivity to pollutants, the activity concentrations of 210Po, 40K, 210Pb, 39 90Sr and 234Th were measured in two types of benthic invertebrates species (mussels and 40 sea urchins) sampled during the period 2012–2018. 41 42 The activity concentrations of 210Po; 40K; 210Pb and 234Th ranged from 38 ± 1 to 325 ± 11 43 Bq kg−1 dry weight (d.w.); 220 ± 10 and 996 ± 46 Bq kg−1 d.w.; from ND (lower than the 44 limit of detection) to 55 ± 8 Bq kg−1 d.w.; and from ND to 70 ± 15 Bq kg−1 d.w., 45 respectively. In all cases, no artificial 90Sr activity was detected in the collected samples. 46 The committed effective dose to humans was calculated to be in the range from 48 to 640 47 μSv year−1. 48 49 50 51 52 53 54 55 56 57 58 59 Keywords: benthic invertebrates; 210Po; 210Pb; 90Sr; 234Th; Balearic Islands 60 61 62 3 There are two well-known sources of radioactivity in the marine environment: 40K and 63 natural decay series of 238U and 232Th; and man-made radionuclides (137Cs, (239+240)Pu or 64 90Sr) (Polykarpov, 1966; Shannon and Cherry, 1967). These chemically-analogue 65 radionuclides of metabolically essential elements are bioaccumulated in tissues of the 66 marine species through different mechanisms (Carvalho, 2018). Therefore, these 67 radionuclides are introduced into the food chain via ingestion of marine food. In order to 68 evaluate intake of radionuclides by human, an assessment of radionuclide concentrations 69 in marine organisms must be carried out. The dose to the body (the energy absorbed from 70 internal irradiation due to ingestion of radionuclides) produces biological effects in 71 humans. An exhaustive radiation dose assessment establishes a baseline that is useful to 72 control any increase due to nuclear accidents or industrial activities (Feroz Khan et al., 73 2014). 74 75 Artificial radionuclides are mainly released in the environment by Nuclear power plant 76 (NPP) accidents (Chernobyl in 1986, or Fukushima Daiichi NPP in 2011), and nuclear 77 weapon tests (during the 1960s) (Fathivand and Amidi, 2007). Among the artificial 78 radionuclides, 90Sr is considered a key radionuclide to be controlled (Castrillejo et al., 79 2016). 90Sr is a primary fission product (Habibi et al., 2015) with a long biological (13 80 years) and nuclear half-life (28.9 years) that persists in the environment for a long time. 81 Furthermore, 90Sr is a chemical analogue of calcium metabolizing in tissues with high 82 calcium content, such as bones, and consequently strontium is one of the most hazardous 83 radionuclides. 84 85 Concerning natural radionuclides, 238U decay chain includes 210Po, 210Pb, and 234Th. The 86 main sources of 210Po (T1/2 = 138 days) and 210Pb (T1/2 = 22.3 years) in the environment 87 4 are: dry and wet fallout of emanated 222Rn from the earth’s crust to the atmosphere 88 (Baskaran, 2011), radioactive decay of 226Ra dissolved in seawater (Bacon et al., 1976; 89 Carvalho and Fowler, 1993), and waste discharges from industries processing 90 technologically enhanced naturally occurring radioactive materials (TENORM) 91 (Carvalho et al., 2010; Villa et al., 2009). 92 93 210Po is a toxic element that releases locally the radiation dose through its alpha-particle 94 decay of 5.3 MeV originating a fatal damage to different organs and tissues (Stewart et 95 al., 2008). It is the major contributor to radiation dose received by humans in sea food, 96 such as fish, crustaceans and molluscs (Dahlgaard, 1996; Wildgust et al., 2000). On the 97 other hand, 210Pb is a beta emitter and the second highest radiotoxic radionuclide in the 98 natural decay chain (Štrok and Smodiš, 2011). Regarding 234Th, it is a natural 99 radionuclide with a half-life of 24.1 days. The radioactive levels of 234Th have been 100 published by previous studies in plankton (Marsh and Buddemeier, 1984; Paschoa et al., 101 1981). However, few studies have been carried out on bioaccumulation of 234Th in marine 102 organisms in the higher trophic levels (Ishikawa et al., 2004). 103 104 Finally, natural 40K has a very long half-life (T1/2 = 1.251×109 years) and the reported 105 activity concentrations represent the natural background levels for marine organisms 106 (Meli et al., 2008). The dose produced by 40K is due to its beta emission and it is negligible 107 compared to the radiation dose associated to 210Po (UNSCEAR, 2008). 108 109 Of all marine species, benthic invertebrates have been widely utilized as bioindicators for 110 assessing the contamination and ecotoxicology taking place in the marine environment 111 (Carvalho et al., 2010; Fonollosa et al., 2017; Francioni et al., 2007; Kiliç et al., 2014; 112 Rožmarić et al., 2012; Thébault et al., 2008; Topcuoǧlu et al., 2003; Uǧur et al., 2011). 113 5 114 As far as we known, there are no previous studies on radioactive pollution in the Balearic 115 Islands in the Western Mediterranean. In view of this fact, the main objectives of this 116 study are (1) to assess the activity concentration of 210Po, 40K, 210Pb, 90Sr and 234Th in two 117 types of benthic invertebrates distributed in the Balearic Islands, and (2) to estimate the 118 annual effective ingestion dose to human population due to seafood consumption. 119 120 Samples were collected at two sampling locations around the Balearic Islands (Western 121 Mediterranean), specifically at Menorca Island (BAL1/01 and BAL1/02) (see Fig. 1). The 122 BAL 1/01 location was at the Port of Mahon, near to the city of approximately 28,000 123 inhabitants. The collection sites are aquaculture zones of marine invertebrates. 124 Radioactivity levels were determined in two commercial invertebrate species regularly 125 sold in the domestic markets. The studied species included one mollusc bivalve species 126 (Mytilus galloprovincialis) and one sea-urchin echinoderm (Paracentrotus lividus). The 127 mussels were not native to Balearic Islands, they were transplanted in autumn from Ebro 128 Delta or Adriatic Sea regions. 129 6 130 Fig. 1. Map showing the study area and sampling stations. 131 132 Samples were collected from 2012 to 2018 at the two locations. The life cycle of the 133 invertebrate species and the commercial extraction periods established the sampling dates 134 (Table 1). 135 136 137 138 Table 1. Sampling locations and period. 139 Location Specie Coordinates Sampling period Puerto de Mahón (BAL 1/01) Mytilus galloprovincialis 39° 53.65′N–04° 16.10′E 2012–2018 Costa Este Menorca (BAL 1/02) Paracentrotus lividus 39° 52.40′N–04° 18.38′E 2012–2017 140 141 7 Adult specimens of the same species per sampling year were pooled together in order to 142 obtain at least, 100 g of dry weight to carry out the analytical methods. At least, 1,000 g 143 of wet flesh of each species were treated for each sampling year. 144 145 In the laboratory, the invertebrate samples were washed with distilled water in order to 146 remove the attached sand/silt. Then, their soft tissues were dissected, weighted, frozen at 147 -20 ºC, and freeze-dried for 24 h. Finally the dehydrated samples were weighted, crushed 148 and homogenized. 149 150 To determine 210Po activity concentration, a known activity of internal tracer 209Po was 151 added to the lyophilized sample in order to calculate the analytical recovery. First, 152 samples were digested with concentrated HNO3 and H2O2 during 24 h at low temperature 153 (<25 ºC) in order to avoid foam formation. The obtained solution was then digested at 154 high temperature (<80 ºC) and slowly evaporated to near dryness on a hot plate. The 155 obtained residue was dissolved again 2 or 3 times with concentrated HNO3 and H2O2 to 156 destroy all the organic material. Finally, the residue was dissolved in 100 mL of 1 M HCl 157 and filtered through a 0.45 µm pore filter. About 0.1 g of ascorbic acid salt was added to 158 the solution as a reducing agent. A silver disc was introduced into the solution 159 continuously stirred for 4 h at 85-90 ºC and pH 1.5–2.0 being 210Po spontaneously plated 160 onto the disc. The disc was then removed, washed with distilled water and acetone, and 161 dried. An alpha-spectrometry instrument (Alpha Analyst, Canberra) containing a 162 Passivated Implanted Planar Silicon (PIPS) detector was used for counting the disc. Alpha 163 spectrum analysis was performed using Alpha Analyst software taking into account the 164 decay corrections for 210Po and 209Po activities obtaining high chemical yields (>70%) 165 (Hurtado-Bermudez et al., 2017). 166 167 8 The radioanalytical method accuracy was validated by the analysis of certified reference 168 materials (CRM) provided by the International Atomic Energy Agency (IAEA-437, 169 IAEA-330 and IAEA-414). It was observed that obtained values were in good agreement 170 with the recommended values. 171 172 Regarding gamma-ray emitting radionuclides, lyophilized samples were sealed into 80 173 mL cylindrical beakers and were allowed to elapse at least 4 weeks before counting to 174 reach secular equilibrium between 226Ra and their daughters (214Pb and 214Bi). Samples 175 were counted for 1–3 days using a low-background Canberra HPGe GR-6022 detector 176 with 60% relative efficiency, surrounded by a 10 cm thick high-purity lead shield. The 177 absolute efficiencies of the detectors were calculated using Canberra LabSOCS software 178 taking into account the effect of self-attenuation of low energy gamma-rays within the 179 sample (Hurtado and Villa, 2010). The spectra were analyzed using Canberra Genie 2000 180 gamma software v3.2. 210Pb activity concentration was calculated by 46.5 keV gamma 181 emission, 226Ra activity concentration was obtained through 295 and 351 keV gamma-182 rays emitted by 214Pb. 40K was estimated using 1460.8 keV gamma emission. 234Th 183 activity concentration was assessed by analyzing the 63.3 keV gamma-ray. Each 184 uncertainty of activity concentration covered one sigma counting statistics. 185 186 The validation of the gamma-ray spectrometry analyses was carried out through the 187 successful participation on several intercomparison exercises organized by ICRM on 188 efficiency calibration and coincidence-summing correction (Lépy et al., 2012; Vidmar et 189 al., 2008). 190 191 90Sr activity concentration was determined by measuring its daughter 90Y in secular 192 equilibrium (Rivera-Silva et al., 2019). Samples were dried and ashed at 610ºC to remove 193 9 organic materials, and then 1 to 3 g of ashes were used for the analysis. About 20 mg of 194 Y carrier (Y2O3) was added to the ashes and then dissolved in 60 mL of 1 M HCl. Then, 195 pH value was adjusted to 1.2, by the addition of 2 g of citric and ascorbic acid and, finally, 196 it was transferred into a separation funnel containing 60 mL of 5% HDEHP in toluene. 197 After shaking for 5 minutes, the Sr/Y were separated whereas Y remained in the organic 198 phase. Y was back-extracted from HDEHP by shaking for 1 minute with 60 mL 0.08 M 199 HCl, and then 50 mL 3 M HCl. Yttrium was precipitated in the aqueous phase at pH to 200 9-10 as Y(OH)3. Then, it was dissolved in 1 mL of 65% HNO3, and transferred into a 201 plastic scintillation vial containing 19 mL of distilled water. The 90Y activity was 202 immediately measured in an ultralow background liquid scintillation spectrometer, 203 Quantulus 1220TM (PerkinElmer, Inc.) through Cerenkov counting. The spectra were 204 acquired and analyzed by WinQ and EASYView software. After the measurement, the 205 recovery yield was obtained by complexometric titration of Y with EDTA. 206 207 The radioanalytical method accuracy was validated by the analysis of certified reference 208 materials (CRM) provided by the International Atomic Energy Agency (IAEA-473, 209 IAEA-330 and IAEA-384). The obtained values were in good agreement with the 210 recommended values. 211 212 Activity concentrations of 90Sr, 210Po; 40K; 210Pb and 234Th in benthic invertebrate 213 samples in the sampling sites and for each sampling campaign are presented in Table 2. 214 215 216 217 218 219 220 16 Table 2. The obtained values were in range from 102-640 μSv/year to 48-111 μSv/year 338 for mussels and sea urchin, respectively. The annual ingestion doses, calculated for the 339 analyzed mussels, are similar to those reported in other studies (see Table 3), and are 340 within the interval of ingestion dose due to natural radiation (200–1000 μSv/year) 341 (UNSCEAR, 2011). However, the annual effective ingestion dose strongly depends on 342 the annual intake of seafood via diet. This fact should be taken into account when 343 comparing annual effective doses between different regions or countries. 344 345 346 References 347 348 349 350 Ambrosio, L., Russo, R., Salzano, A.M., Serpe, F.P., Ariano, A., Tommasi, N. De, Piaz, 351 F.D., Severino, L., 2018. Accumulation of Polychlorinated Biphenyls in Mussels: 352 A Proteomic Study. J. Food Prot. 81, 316–324. doi:10.4315/0362-028X.JFP-17-353 148 354 Bacon, M.P., Spencer, D.W., Brewer, P.G., 1976. 210Pb226Ra and 210Po210Pb 355 disequilibria in seawater and suspended particulate matter. Earth Planet. Sci. Lett. 356 32, 277–296. doi:10.1016/0012-821X(76)90068-6 357 Baskaran, M., 2011. Po-210 and Pb-210 as atmospheric tracers and global atmospheric 358 Pb-210 fallout: A Review. J. Environ. Radioact. 102, 500–513. 359 doi:10.1016/j.jenvrad.2010.10.007 360 Carvalho, F.P., 2018. Radionuclide concentration processes in marine organisms: A 361 comprehensive review. J. Environ. Radioact. 186, 124–130. 362 doi:https://doi.org/10.1016/j.jenvrad.2017.11.002 363 Carvalho, F.P., Fowler, S.W., 1993. An experimental study on the bioaccumulation and 364 turnover of polonium-210 and lead-210 in marine shrimp. Mar. Ecol. Prog. Ser. 365 102, 125–134. doi:10.3354/meps102125 366 Carvalho, F.P., Oliveira, J.M., Alberto, G., 2011. Factors affecting 210Po and 210Pb 367 activity concentrations in mussels and implications for environmental bio-368 17 monitoring programmes. J. Environ. Radioact. 102, 128–137. 369 doi:10.1016/j.jenvrad.2010.11.003 370 Carvalho, F.P., Oliveira, J.M., Alberto, G., Vives i Batlle, J., 2010. Allometric 371 relationships of 210Po and 210Pb in mussels and their application to 372 environmental monitoring. Mar. Pollut. Bull. 60, 1734–1742. 373 doi:10.1016/j.marpolbul.2010.06.025 374 Castrillejo, M., Casacuberta, N., Breier, C.F., Pike, S.M., Masqu??, P., Buesseler, K.O., 375 2016. Reassessment of 90Sr, 137Cs, and 134Cs in the Coast off Japan Derived 376 from the Fukushima Dai-ichi Nuclear Accident. Environ. Sci. Technol. 50, 173–377 180. doi:10.1021/acs.est.5b03903 378 Charmasson, S., Le Faouder, A., Loyen, J., Cosson, R.P., Sarradin, P.-M., 2011. 210Po 379 and 210Pb in the tissues of the deep-sea hydrothermal vent mussel Bathymodiolus 380 azoricus from the Menez Gwen field (Mid-Atlantic Ridge). Sci. Total Environ. 381 409, 771–777. doi:10.1016/j.scitotenv.2010.10.025 382 Dahlgaard, H., 1996. Polonium-210 in mussels and fish from the Baltic-North sea 383 estuary. J. Environ. Radioact. 32, 91–96. doi:10.1016/0265-931X(95)00081-K 384 Desideri, D., Meli, M.A., Roselli, C., 2011. Natural radionuclides in seafood from the 385 central Adriatic Sea (Italy). Health Phys. 100, 160–166. 386 doi:10.1097/HP.0b013e3181ea50d4 387 Deudero, S., Box, A., March, D., Valencia, J.M., Grau, A.M., Tintore, J., Calvo, M., 388 Caixach, J., 2007. Organic compounds temporal trends at some invertebrate 389 species from the Balearics, Western Mediterranean. Chemosphere 68, 1650–1659. 390 doi:https://doi.org/10.1016/j.chemosphere.2007.03.070 391 Fathivand, A.A., Amidi, J., 2007. Derived intervention levels for edible parts of 392 foodstuffs consumed in Iran. Health Phys. 93, 109–112. 393 doi:10.1097/01.HP.0000259902.46364.a2 394 Feroz Khan, M., Godwin Wesley, S., Rajan, M.P., 2014. Polonium-210 in marine 395 mussels (bivalve molluscs) inhabiting the southern coast of India. J. Environ. 396 Radioact. 138, 410–416. doi:https://doi.org/10.1016/j.jenvrad.2014.06.023 397 Fonollosa, E., Peñalver, A., Aguilar, C., Borrull, F., 2017. Bioaccumulation of natural 398 radionuclides in molluscs from the Ebro Delta area. Environ. Sci. Pollut. Res. 24, 399 208–214. doi:10.1007/s11356-016-7783-x 400 Fowler, S.W., 2011. 210Po in the marine environment with emphasis on its behaviour 401 within the biosphere. J. Environ. Radioact. 102, 448–461. 402 18 doi:https://doi.org/10.1016/j.jenvrad.2010.10.008 403 Francioni, E., de L.R. Wagener, A., Scofield, A.L., Depledge, M.H., Cavalier, B., 2007. 404 Evaluation of the mussel Perna perna as a biomonitor of polycyclic aromatic 405 hydrocarbon (PAH) exposure and effects. Mar. Pollut. Bull. 54, 329–338. 406 doi:10.1016/j.marpolbul.2006.11.003 407 Habibi, A., Boulet, B., Gleizes, M., Larivière, D., Cote, G., 2015. Rapid determination 408 of actinides and (90)Sr in river water. Anal. Chim. Acta 883, 109–16. 409 doi:10.1016/j.aca.2015.04.025 410 Hurtado-Bermúdez, S., Jurado-González, J.A., Santos, J.L., Díaz-Amigo, C.F., 411 Aparicio, I., Mas, J.L., Alonso, E., 2018. Baseline activity concentration of 210Po 412 and 210Pb and dose assessment in bivalve molluscs at the Andalusian coast. Mar. 413 Pollut. Bull. 133, 711–716. doi:10.1016/j.marpolbul.2018.06.034 414 Hurtado-Bermúdez, S., Jurado-González, J.A., Santos, J.L., Díaz-Amigo, C.F., 415 Aparicio, I., Más, J.L., Alonso, E., 2019. Geographical origin of bivalve molluscs 416 in coastal areas using natural radioactivity fingerprinting and multivariate 417 statistical analyses: Andalusian coast as case of study. J. Hazard. Mater. 367, 706–418 714. doi:https://doi.org/10.1016/j.jhazmat.2019.01.027 419 Hurtado-Bermudez, S., Mas, J.L., Villa-Alfageme, M., 2017. A sequential 420 determination of90Sr and210Po in food samples. Food Chem. 229. 421 doi:10.1016/j.foodchem.2017.02.077 422 Hurtado, S., Villa, M., 2010. An intercomparison of Monte Carlo codes used for in-situ 423 gamma-ray spectrometry. Radiat. Meas. 45, 923–927. 424 doi:10.1016/j.radmeas.2010.06.001 425 IAEA, 2014. Radiation Protection and Safety of Radiation Sources: International Basic 426 Safety Standards (GSR Part 3). Int. At. Energy Agency Vienna 3, 471. 427 doi:STI/PUB/1578 428 Ishikawa, Y., Kagaya, H., Saga, K., 2004. Biomagnification of 7Be, 234Th, and 228Ra 429 in marine organisms near the northern Pacific coast of Japan. J. Environ. Radioact. 430 76, 103–112. doi:https://doi.org/10.1016/j.jenvrad.2004.03.021 431 Kiliç, T., Belivermiş, M., Çotuk, Y., Topçuoǧlu, S., 2014. Radioactivity concentrations 432 in mussel (Mytilus galloprovincialis) of Turkish Sea coast and contribution of 433 210Po to the radiation dose. Mar. Pollut. Bull. 80, 325–329. 434 doi:10.1016/j.marpolbul.2013.12.037 435 Kim, S.H., Hong, G.H., Lee, H.M., Cho, B.E., 2017. 210Po in the marine biota of 436 19 Korean coastal waters and the effective dose from seafood consumption. J. 437 Environ. Radioact. 174, 30–37. doi:https://doi.org/10.1016/j.jenvrad.2016.11.001 438 Lépy, M.C., Altzitzoglou, T., Anagnostakis, M.J., Capogni, M., Ceccatelli, A., De 439 Felice, P., Djurasevic, M., Dryak, P., Fazio, A., Ferreux, L., Giampaoli, A., Han, 440 J.B., Hurtado, S., Kandic, A., Kanisch, G., Karfopoulos, K.L., Klemola, S., Kovar, 441 P., Laubenstein, M., Lee, J.H., Lee, J.M., Lee, K.B., Pierre, S., Carvalhal, G., 442 Sima, O., Van Tao, C., Thien Thanh, T., Vidmar, T., Vukanac, I., Yang, M.J., 443 2012. Intercomparison of methods for coincidence summing corrections in 444 gamma-ray spectrometry-part II (volume sources). Appl. Radiat. Isot. 70, 2112–445 2118. doi:10.1016/j.apradiso.2012.02.079 446 Marsh, K.V., Buddemeier, R.W., 1984. Radionuclides in plankton from the South 447 Pacific Basin, US DOE Technical Report, UCRL-89843. doi:10.2172/5078845 448 McDonald, P., Baxter, M.S., Scott, E.M., 1996. Technological enhancement of natural 449 radionuclides in the marine environment. J. Environ. Radioact. 32, 67–90. 450 doi:10.1016/0265-931X(95)00080-T 451 Meli, M.A., Desideri, D., Roselli, C., Feduzi, L., 2008. Natural Radioactivity in the 452 Mussel Mytilus Galloprovincialis Derived from the Central Adriatic Sea (Italy). J. 453 Toxicol. Environ. Heal. Part A Curr. Issues 71, 1270–1278. 454 doi:http://dx.doi.org/10.1080/01932690801934562 455 Nonova, T., Tosheva, Z., 2016. 90Sr, 210Pb, 210Po and Ra isotopes in marine 456 macroalgae and mussel Mytilus galloprovincialis from the Bulgarian Black Sea 457 zone. J. Radioanal. Nucl. Chem. 307, 1183–1194. doi:10.1007/s10967-015-4502-x 458 Paschoa, A.S., Baptista, G.B., Wrenn, M.E., Eisenbud, M., 1981. Dosimetry of Natural 459 and Man-Made Alpha Emitters in Plankton. AN - 15522003; 348656, PROC. 460 SER. IAEA. pp. 695-716. 1981. 461 Polykarpov, G.G., 1966. Radioecology of Aquatic Organisms. North Holland, New 462 York. 463 Rivera-Silva, J., Hurtado-Bermúdez, S., Villa-Alfageme, M., Manjón, G., 2019. 464 Comparison and validation of methods for the determination of 90Sr by Cerenkov 465 counting in biological and sediment samples, including green chemistry metrics. J. 466 Radioanal. Nucl. Chem. 320, 109–122. doi:10.1007/s10967-019-06436-6 467 Rožmarić, M., Rogić, M., Benedik, L., Štrok, M., Barišić, D., Gojmerac Ivšić, A., 2012. 468 210Po and 210Pb activity concentrations in Mytilus galloprovincialis from 469 Croatian Adriatic coast with the related dose assessment to the coastal population. 470 20 Chemosphere 87, 1295–1300. doi:10.1016/j.chemosphere.2012.01.039 471 Shannon, L. V, Cherry, R.D., 1967. Polonium-210 in marine plankton [2]. Nature 216, 472 352–353. doi:10.1038/216352a0 473 Stewart, G.M., Fowler, S.W., Fisher, N.S., 2008. Chapter 8 The Bioaccumulation of U- 474 and Th-Series Radionuclides in Marine Organisms. Radioact. Environ. 475 doi:10.1016/S1569-4860(07)00008-3 476 Štrok, M., Smodiš, B., 2011. Levels of 210Po and 210Pb in fish and molluscs in 477 Slovenia and the related dose assessment to the population. Chemosphere 82, 970–478 976. doi:10.1016/j.chemosphere.2010.10.075 479 Thébault, H., Rodriguez y Baena, A.M., Andral, B., Barisic, D., Albaladejo, J.B., 480 Bologa, A.S., Boudjenoun, R., Delfanti, R., Egorov, V.N., El Khoukhi, T., Florou, 481 H., Kniewald, G., Noureddine, A., Patrascu, V., Pham, M.K., Scarpato, A., 482 Stokozov, N.A., Topcuoglu, S., Warnau, M., 2008. 137Cs baseline levels in the 483 Mediterranean and Black Sea: A cross-basin survey of the CIESM Mediterranean 484 Mussel Watch programme. Mar. Pollut. Bull. 57, 801–806. 485 doi:10.1016/j.marpolbul.2007.11.010 486 Topcuoǧlu, S., Ergül, H.A., Baysal, A., Ölmez, E., Kut, D., 2003. Determination of 487 radionuclide and heavy metal concentrations in biota and sediment samples from 488 pazar and rize stations in the eastern Black Sea. Fresenius Environ. Bull. 12, 695–489 699. 490 Uǧur, A., Özden, B., Filizok, I., 2011. Spatial and temporal variability of 210Po and 491 210Pb in mussels (Mytilus galloprovincialis) at the Turkish coast of the Aegean 492 Sea. Chemosphere 83, 1102–1107. doi:10.1016/j.chemosphere.2011.01.032 493 Uğur, A., Yener, G., Bassari, A., 2002. Trace metals and 210Po (210Pb) concentrations 494 in mussels (Mytilus galloprovincialis) consumed at western Anatolia. Appl. Radiat. 495 Isot. 57, 565–571. doi:10.1016/s0969-8043(02)00141-0 496 UNSCEAR, 2011. Report of the United Nations Scientific Committee on the Effects of 497 Atomic Radiation 2010 -, United Nations Publication. 498 doi:10.1080/09553007014550131 499 UNSCEAR, 2008. Sources and effects of ionizing radiation. Rep. to Gen. Assem. I, 500 116. 501 Vidmar, T., Aubineau-Laniece, I., Anagnostakis, M.J., Arnold, D., Brettner-Messler, R., 502 Budjas, D., Capogni, M., Dias, M.S., De Geer, L.E., Fazio, A., Gasparro, J., Hult, 503 M., Hurtado, S., Jurado Vargas, M., Laubenstein, M., Lee, K.B., Lee, Y.K., Lepy, 504 21 M.C., Maringer, F.J., Medina Peyres, V., Mille, M., Moralles, M., Nour, S., 505 Plenteda, R., Rubio Montero, M.P., Sima, O., Tomei, C., Vidmar, G., 2008. An 506 intercomparison of Monte Carlo codes used in gamma-ray spectrometry. Appl. 507 Radiat. Isot. 66, 764–768. doi:10.1016/j.apradiso.2008.02.015 508 Villa, M., Mosqueda, F., Hurtado, S., Mantero, J., Manjón, G., Periañez, R., Vaca, F., 509 García-Tenorio, R., 2009. Contamination and restoration of an estuary affected by 510 phosphogypsum releases. Sci. Total Environ. 408. 511 doi:10.1016/j.scitotenv.2009.09.028 512 Wildgust, M.A., McDonald, P., White, K.N., 2000. Assimilation of 210Po by the 513 mussel Mytilus edulis from the alga Isochrysis galbana. Mar. Biol. 136, 49–53. 514 515