Plutonium AMS measurements in Yangtze River estuary sediment

Plutonium isotope measurements from across continental Australia

“…It is plausible that the more consistent rainfall in the south-east of Australia removes more of the fallout isotopes from the atmosphere because it falls year round, whereas in the north there is essentially no rainfall for 4 months of the year during the dry season, while the intense rains of the wet season rapidly remove any fallout isotopes that are present in the atmosphere at the time leaving little for subsequent rainfall. Such an effect has been reported by Knies et al [25] who measured 10 Be and 36 Cl in the course of individual rainfall events and found significantly more isotope near the beginning of an event than at the end. In order to investigate this further, we are currently measuring other fallout nuclides in the samples, and making a more detailed assessment of regional fallout at the sites using annual fallout and rainfall records for each region.…”

“…The reduction in agricultural productivity, in part brought about by differences between soil production and loss rates, is a major issue for land management across much of the mainland and plutonium measurements are currently being used to assess the balance between soil loss and formation rates [8]. Plutonium isotopes have also found use as chronological markers in fresh and estuarine sediments [9,10]: the horizon of the first appearance of individual isotopes in the sediment profile, the peak(s) in fallout concentrations and changes in the plutonium isotope ratios all correspond to known ages. More recently, coral archives have been shown to provide historic records of shifts in the plutonium isotopic ratios and have potential for use as a probe of changes in ocean currents that could potentially arise as a result of climate change [11].…”

Using239Pu as a tracer for fine sediment sources in the Daly River, Northern Australia

“…The most commonly used anthropogenic isotope to assess soil redistribution rates is caesium-137 ( 137 Cs). [14]) have been used as soil and sediment tracers [15][16][17][18][19][20][21][22][23][24]. Like 137 C, they fell out in rain and attached strongly to soil particles upon reaching Earth's surface, and like 137 Cs, they have been shown to be suitable tracers of soil erosion and sediment transport [16,19,21,25].…”

No Fukushima Dai-ichi derived plutonium signal in marine sediments collected 1.5–57 km from the reactors

“…In contrast to the Japanese terrestrial environment, where pre Fukushima 240 Pu/ 239 Pu ratios were found to be in accordance with global fallout, nuclear weapon detonations at the Pacific Proving Grounds (PPG) have been linked to elevated Pu ratios in samples from off the Japanese coast as well as in most of the North Pacific region. The 240 Pu/ 239 Pu atom ratios in samples of riverine and marine sediments as well as seawater collected before the FDNPP accident were found to range within 0.17 and 0.32 (Oikawa et al, 2015;Tims et al, 2010;Zheng and Yamada, 2004). Seawater and sediment samples from this area will be influenced by global fallout and long-range transported debris from tests at the PPG and particularly those that took place at the Bikini andEniwetok atolls during 1946 -1958.…”

“…Seawater and sediment samples from this area will be influenced by global fallout and long-range transported debris from tests at the PPG and particularly those that took place at the Bikini andEniwetok atolls during 1946 -1958. A total of 66 nuclear weapon tests were conducted at the PPG, and in the early 1950s some very high yield detonations were conducted (Björklund and Goliath, 2009;Tims et al, 2010). Enhanced levels of the higher mass Pu isotopes were produced in the early detonations by multiple neutron captures in 238 U present in natural U-tamper materials (Diamond et al, 1960).…”