Centre for Marine Ecosystem Research, School of Science, Edith Cowan University, Joondalup, WA, 6027, Australia; School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD, 4072, Australia.
Radiation and Nuclear Sciences Unit, Forensic and Scientific Services, Queensland Health Department of Health, Coopers Plains, QLD, 4108, Australia; Australian Radiation Protection and Nuclear Safety Agency, Yallambie, VIC, 3085, Australia.
J Environ Radioact. 2024 Sep;278:107505. doi: 10.1016/j.jenvrad.2024.107505. Epub 2024 Jul 22.
Three nuclear weapons tests were conducted in the 1950s at the Montebello Islands, Western Australia. The detonations were of different yields and configurations (two tower tests, one ship test), and led to substantial radionuclide contamination within the surrounding terrestrial and marine ecosystems. The region possesses great ecological and recreational significance, particularly within the marine environment. However, studies conducted so far have largely neglected the marine ecosystem which makes up the majority of the Montebello Island Marine Park and in which most test fallout would have deposited. Here we investigated the distribution of the transuranic radionuclides Pu, Pu and Am in marine sediment from the Montebello Islands. Marine sediment samples near Operation Mosaic G2 and Operation Hurricane were collected and analysed by gamma and alpha spectrometry. Activity concentrations of Pu across both series ranged from 45 to 2900 Bq kg, while Am levels ranged from 2.8 to 70 Bq kg. Higher activity concentrations were observed in sediment near the land-based, higher yield Mosaic G2 test, compared with the ship-based, lower yield Hurricane test. Sediment samples located closer to the detonation site were also observed to have higher activity concentrations. Radioactive particles of 0.94 mm and 1.5 mm in diameter were identified by analysis of size-fractioned sediment via investigation of Eu levels, photostimulated autoradiography and point gamma spectroscopy. Particles were confirmed to have transuranic radionuclide interiors, with surface coatings which were dominated by vitrified CaCO Their long-term resistance to weathering and subsequent persistence in the marine environment can therefore be attributed to their coated structural form. Our study confirms the persistence of transuranic radionuclides in Montebello Island marine sediment and highlights the need for additional studies to improve our understanding of the nuclear legacy in this region.
在 20 世纪 50 年代，澳大利亚西部的蒙特贝洛群岛进行了三次核武器试验。这些爆炸的爆炸威力和配置不同（两次塔式试验，一次舰上试验），导致周围陆地和海洋生态系统中存在大量放射性核素污染。该地区具有重要的生态和娱乐意义，特别是在海洋环境中。然而，迄今为止进行的研究在很大程度上忽视了构成蒙特贝洛岛海洋公园大部分的海洋生态系统，而大部分试验沉降物都沉积在其中。在这里，我们研究了来自蒙特贝洛群岛的海洋沉积物中钚、钚和镅这三种超铀放射性核素的分布。在“马赛克行动 G2”和“飓风行动”附近收集并分析了海洋沉积物样本，采用伽马和阿尔法谱法进行了分析。两个系列的 Pu 跨距活动浓度范围为 45 至 2900 Bq kg，而 Am 水平范围为 2.8 至 70 Bq kg。与基于船舶、低产的“飓风行动”相比，基于陆地、高产的“马赛克行动 G2”试验附近的沉积物中观察到更高的活性浓度。靠近爆炸点的沉积物样本也观察到更高的活性浓度。通过对 Eu 水平、光刺激自动成像和点伽马光谱进行分析，对大小分级的沉积物进行分析，确定了直径为 0.94 毫米和 1.5 毫米的放射性颗粒。颗粒被确认为具有超铀放射性核素内部，表面涂层主要由玻璃化的 CaCO 组成。它们对风化的长期抵抗力以及随后在海洋环境中的持久性可归因于它们的涂层结构形式。我们的研究证实了超铀放射性核素在蒙特贝洛岛海洋沉积物中的持久性，并强调需要进行更多研究来提高我们对该地区核遗留物的认识。
