Accumulation of 210Po by spiny dogfish (Squalus acanthias), elephant fish (Callorhinchus milii) and red gurnard (Chelodonichthys kumu) in New Zealand shelf waters

Concentrations of the natural radionuclide 210Po in the livers of 81 individual specimens of three fish species collected from waters of the Otago continental shelf, New Zealand, have been measured: spiny dogfish (Squalus acanthias), 4.2 ± 1.8 Bq kg-1wet weight (mean ± standard deviation, n=48); elephant fish (Callorhinchus milii), 136 ± 39 Bq kg-1 (n = 7); and red gurnard (Chelodonichthys kumu), 38 ± 13 Bq kg-1 (n = 26). Separate measurements showed that only a negligible fraction of the 210Po was supported by decay of the 210Pb parent (210Po/210Pb activity ratios were 15, 134 and 5.9 respectively for the three species), indicating that direct uptake of 210Po into the liver balances losses from excretion and radioactive decay. The radiation dose from 210Po in the livers accounted for between 88% and 99% of the total internal absorbed dose received by the fish species. The activity of 210Po in sea water from the study area was 0.9-2.2 mBq L-1, yielding concentration factors for 210Po in liver tissue in the range 3 x 103 to 100 x 103. No significant monophasic relationships were observed between the 210Po results and the measured concentrations of the elements Cd, Cu, Fe, Mn, Zn and Pb, except that Pb and 210Po were correlated (r = 0.511 ) in C. kumu. Copyright (1997) CSIRO Publishing