210Po concentration in fish, algae, mussel and beach sand samples in Turkish coast of the Black Sea

The natural radionuclide 210Po is the major contributor to the radiation dose received by humans from the sea food consumption. The main source of 210Po in the environment is the exhalation of 222Rn gas from the ground into the atmosphere. The radionuclides fall to the sea water and oceans together with aerosol particles by washout and sedimentation. The other source include burning of fossil fuel, uranium, phosphate and lead ore processing industries and tetraethyl lead used for car engines. The entrance of the radionuclides to the human body are via inhalation or ingestion. The major contribution for 210Po received via food consumption especially is originated from fish and shell fish by which it is strongly accumulated in relatively high concentration. This can lead to increase the radiation dose delivered to man by significant factor. In this study the concentration of 210Po were determined in algae, fish, mussel and beach sand samples collected from four different coastal zones of the Black Sea in Turkey from selected stations namely Sile, Trabzon, Sinop and Zonguldak during the period of 1998-2001. The sampling and analysis were carried out as a part of the 'Marine Environmental Assessment of the Black Sea Region' Technical Cooperation Project, RER/2/003 undertaken by the six Black Sea countries which is supported by IAEA. For the determination of 210Po in samples the standard techniques was used. Known activity of 209Po were added as an isotopic tracer. Samples were completely dissolved with mineral acids (HNO3, H2O2). When the solution was clear, concentrated HCl was added and the solution was gently evaporated to near dryness. After evaporation, polonium was plated onto silver disc in 0.5 M HCl in presence of ascorbic acid. Alpha counting of sample was performed using a silicon surface barrier detectors connected to a PC. The mean 210Po concentrations measured in mussel, algae, fish and beach sand samples from the four different locations on Turkish coast of Black Sea namely Sile, Sinop, Trabzon and Zonguldak are presented. The mean 210Po concentrations over the study period in the beach sand and algae was observed to vary between 8.3 - 18.5 Bq.kg-1dry and 15.4 - 29.9 Bq.kg-1dry, respectively while those in fish samples for T. trachurus, M. Barbatus and M. euxinus were found to vary between 1.9 - 7.4 Bq.kg-1wet, 5.8-6.7 Bq.kg-1wet and 1.3 - 1.6 Bq.kg-1wet respectively. The mean 210Po concentration of the mussels used for human consumption having shell length ≥ 5 cm averages is found to be changing between 18.4 - 32.1 Bq.kg-1wet. Reliable systematic data is accumulated as a result of joint monitoring work of the Marine Environmental Assessment of the Black Sea Region Technical Cooperation Project. A preliminary comparison of the values obtained by the project group are in good agreement. However further study on the sea food consumption habits of the Turkish Black Sea population and intake dose assessment for 210Po must be undertaken in order to cover public health concern due to radioactivity in the Black Sea marine environment