First evidence of plutonium and uranium fallout on a Southern Ocean Island (Macquarie Island, 54°S, 158°E)

• Other Authors: SAUNDERS, KRYSTYNA (hasPrincipalInvestigator), SAUNDERS, KRYSTYNA (processor), Australian Antarctic Data Centre (publisher)
• Format: Dataset
• Language: unknown
• Published: Australian Antarctic Data Centre
• Subjects: geoscientificInformation; inlandWaters; NUCLEAR RADIATION EXPOSURE; EARTH SCIENCE; HUMAN DIMENSIONS; ENVIRONMENTAL IMPACTS; NUCLEAR ENERGY PRODUCTION/USE; ECONOMIC RESOURCES; ENERGY PRODUCTION/USE; ISOTOPES; PALEOCLIMATE; OCEAN/LAKE RECORDS; FALLOUT; NUCLEAR MONITORING; SEDIMENT CORERS; LABORATORY; FIELD SURVEYS; OCEAN > SOUTHERN OCEAN > MACQUARIE ISLAND; GEOGRAPHIC REGION > POLAR; Antarctic; Pacific; Southern Ocean; Antarc*; Macquarie Island; Ocean Island
• Online Access: https://researchdata.edu.au/first-evidence-plutonium-54s-158e/1821972; https://doi.org/10.26179/9zkj-6g87; https://data.aad.gov.au/metadata/records/AAS_4156_Macquarie_Island_Plutonium_Uranium; http://nla.gov.au/nla.party-617536

This plutonium and uranium dataset is the first nuclear weapons testing fallout history for a sub-Antarctic island. It is based on a lake sediment core from a small, unnamed lake on Macquarie Island. A 54.0 cm sediment core was collected in 2010. It was sampled at 0.5 cm increments, dated using 210Pb (ages calculated using the constant flux, constant sedimentation model) and 14C. The upper 18.0 cm dated back to ca. 1900 based on 210Pb dating. Plutonium and uranium fallout isotopes 239Pu, 240Pu, 241Pu and 236U were measured on the upper 19.0 cm of the core. Analyses were conducted at the Australian Nuclear Science and Technology Organisation using the Vega Accelerator (https://www.ansto.gov.au/our-facilities/centre-for-accelerator-science/vega-accelerator) following methods described by Hotchkis et al. (2019). The profile demonstrated the onset of nuclear weapons testing at 12.0-12.5 cm (late 1940s based on 210Pb dating) with a 240/239Pu atom ratio of 0.24. This coincides with ratios typical of US testing in the Pacific Proving Grounds, which were the dominant source of global fallout at the time. Concentrations of all isotopes sharply increased between 12.5-9.5 cm and peaked at 9.5-10.0 cm, which, based on 210Pb dating corresponds to ca. 1963. In the late 1950s and early 1960s, there was a change to a lower 240/239Pu atom ratio of 0.17 coinciding with the shift from US testing dominating global fallout to that of the former Soviet Union. Hotchkis, M.A.C. et al. (2019) https://doi.org/10.1016/j.nimb.2018.07.029. Spreadsheet details 1. Notes – information on the sediment core and description of each data worksheet 2. Plutonium_unnamed lake – raw plutonium data 3. Uranium_unnamed lake – raw uranium data Samples collected from an unnamed Lake west of Major Lake, Macquarie Island. Fieldwork conducted in March 2010. Analyses conducted between January-December 2019.