Chapter 2 Linking legacies of the Cold War to arrival of anthropogenic radionuclides in the oceans through the 20th century

Plutonium isotopes as tracers for ocean processes: A review

“…It has been estimated that 12 PBq of 239+240 Pu was deposited in the World Ocean from atmospheric nuclear weapons tests (Hamilton, 2005) and the resulting Pu isotope inventory is shown in Table 2. The Pu isotopic composition in the debris from nuclear detonations varies considerably and depends on the explosive yield, test site location and weapon type (Perkins and Thomas, 1980).…”

“…The Novaya Zemlya testing grounds were used mainly for large-scale atmospheric tests, with most of the debris injected into the stratosphere, and hence contributed mainly to the global fallout with only minor local marine contamination (Osvath et al, 1999;Oughton et al, 2004 Pu atom ratio of about 0.03, equivalent to low-yield nuclear detonations Smith et al, 2000b). Most of the Marshall Islands tests were conducted near the surface, resulting in significant local and regional inputs of Pu to the marine environment (Buesseler, 1997;Robison and Noshkin, 1999 (Noshkin et al, 1987;Hamilton et al, 1996;Donaldson et al, 1997;Robison and Noshkin, 1999;Hamilton, 2005).…”

“…Consequently, about 78 % of the 238 Pu debris was deposited in the Southern Hemisphere, with the highest deposition between latitudes 20 °S and 50 °S (Perkins and Thomas, 1980). The accident has contributed to the total inventory of 238 Pu in the World Ocean with an estimated input of 238 Pu of about 0.32 PBq decay corrected to the year 2000 (Hamilton, 2005). As a result of the SNAP-9A incident the average 238 Pu/ 239+240 Pu activity ratio in global fallout increased from 0.019 ± 0.003 to 0.029 ± 0.005 in the Northern hemisphere and 0.14 ± 0.04 in the Southern hemisphere (values are decay corrected to 2000) (Perkins and Thomas, 1980).…”

Characterization and source term assessments of radioactive particles from Marshall Islands using non-destructive analytical techniques

“…The nuclear test program included air drops (4), barge detonations (35), tower detonations (13), surface detonations (10), and underwater detonations (3). The total yield for all tests conducted on Bikini and Enewetak Atolls was 109 Mt with an estimated fission yield of 53 % [UNSCEAR, 2000;Hamilton 2004]. At Bikini, the total yield was approximately 76.8 Mt with a fission yield of approximately 55 %.…”

“…The terrestrial and marine environments of each atoll are contaminated with a range of fission and activation products, and unfissioned nuclear materials [Hamilton, 2004] In general, a considerable fraction of radioactivity entering the environment from nuclear events such as nuclear weapons accidents, authorized or accidental releases of radioactive effluent and in nuclear weapon detonations is associated with particles. The size distribution of these radioactive particles or aggregates is typically log-normal [Eriksson, 2002; Shevchenko, 2004], i.e., most of the activity is carried by relatively few larger-sized particles.…”