Baseline concentration of 210Po in Sargassum from the Northern Gulf

The concentration of the 210Po is of enormous interest because of its large contribution to the natural radiation dose received by marine organisms and human populations consuming seafood. In fact natural 210Po is responsible for higher radiation doses to humans consuming marine products than is plutonium and other man-made radionuclides. Many marine organisms are capable of concentrating 210Po in their tissues. 210Po is an alpha emitter in the 238U series, with 138-d half-life, that is supplied to seawater from atmospheric inputs and river runoff, however, the main source of 210Po in the environment is 222Rn exhalation from the ground. Assessing the impact of radionuclides in the environment requires the establishment of baseline levels in the environmental compartments. The objective of this study was to establish baseline levels in Sargassum. Two most common species of Sargassum found in the northern Gulf were analysed for 210Po. These macro-algae were collected from three different locations during January 2013. This study sets the baseline for 210Po concentration in northern Gulf, 210Po is absorbed from water and concentrated by Phytoplankton and macro-algae. This concentrated 210Po can then be passed along to the next trophic level of the marine food web. The 210Po concentration measured in Sargassum boveanum (4.405 - 4.952 BqKg-1) was significantly higher (p>0.084) than Sargassum oligocystum (3.838 - 4.358 BqKg-1). The 210Po concentration in these seaweeds from the Arabian/Persian Gulf were substantially lower than those found in various Phytoplankton and macro-algae species from other regions; this may be due to the lower background 210Po concentration in the Kuwait marine waters (0.282 - 0.382 mBq l-1). The 210Po concentrations in seawater measured at the 3 stations during January 2013 were less than those reported previously from the same region sampled in May 2010. The lower 210Po concentration might be a result of higher winter - spring time productivity of seaweeds in the Gulf that may have had a quenching effect due to biological dilution, resulting in a 210Po depletion in seawater. The concentration factor for Sargassam boveanum varied between 1.3 - 1.6 8 104 and for Sargassam oligocystum between 1.1 - 1.6 8 104, these values are approximately 10 times higher than the IAEA recommended value of 1 * 103. Document available in abstract form only. (authors)