ANSTO, Sydney, Australia.
ANSTO, Sydney, Australia.
Sci Total Environ. 2019 Nov 15;691:572-583. doi: 10.1016/j.scitotenv.2019.06.531. Epub 2019 Jul 2.
Since the 1956 completion of nuclear testing at the Montebello Islands, Western Australia, this remote uninhabited island group has been relatively undisturbed (no major remediations) and currently functions as high-value marine and terrestrial habitat within the Montebello/Barrow Islands Marine Conservation Reserves. The former weapons testing sites, therefore, provide a unique opportunity for assessing the fate and behaviour of Anthropocene radionuclides subjected to natural processes across a range of shallow-marine to island-terrestrial ecological units (ecotopes). We collected soil, sediment and biota samples and analysed their radionuclide content using gamma and alpha spectrometry, photostimulated luminescence autoradiography and accelerator mass spectrometry. We found the activity levels of the fission and neutron-activation products have decreased by ~hundred-fold near the ground zero locations. However, Pu concentrations remain elevated, some of which are high relative to most other Australian and international sites (up to 25,050 Bq kg of Pu). Across ecotopes, Pu ranked from highest to lowest in the following order: island soils > dunes > foredunes > marine sediments > and beach intertidal zone. Low values of Pu and other radionuclides were detected in all local wildlife tested including endangered species. Activity concentrations ranked (highest to lowest) terrestrial arthropods > terrestrial mammal and reptile bones > algae > oyster flesh > whole crab > sea turtle bone > stingray and teleost fish livers > sea cucumber flesh > sea turtle skin > teleost fish muscle. The three detonations (one from within a ship and two from 30 m towers) resulted in differing contaminant forms, with the ship detonation producing the highest activity concentrations and finer more inhalable particulate forms. The three sites are distinct in their Pu and Pu atom ratios, including the Pu transported by natural process or within migratory living organisms.
自 1956 年澳大利亚西部蒙特贝洛群岛核试验完成以来，这个偏远无人居住的岛屿群相对未受干扰（没有进行重大补救），目前作为蒙特贝洛/巴罗群岛海洋保护区内具有高价值的海洋和陆地生境发挥作用。因此，这些前武器试验场为评估在一系列浅海到岛屿陆地生态单元（生态位）中受自然过程影响的人类世放射性核素的命运和行为提供了独特的机会。我们收集了土壤、沉积物和生物群样本，并使用伽马和阿尔法光谱法、光激发发光放射自显影和加速器质谱分析法分析了它们的放射性核素含量。我们发现，在接近零地带的位置，裂变和中子活化产物的活性水平下降了约一百倍。然而，钚的浓度仍然很高，其中一些相对于大多数其他澳大利亚和国际地点（高达 25,050 贝克勒尔公斤钚）来说仍然很高。在生态位中，钚的浓度从高到低依次为：岛屿土壤>沙丘>前沙丘>海洋沉积物>和海滩潮间带。在所有测试的当地野生动物中，包括濒危物种，都检测到钚和其他放射性核素的低浓度。活性浓度排名（从高到低）为：陆地节肢动物>陆地哺乳动物和爬行动物骨骼>藻类>牡蛎肉>整个螃蟹>海龟骨>黄貂鱼和硬骨鱼肝脏>海参肉>海龟皮>硬骨鱼肌肉。三次爆炸（一次来自一艘船内，两次来自 30 米高的塔）导致了不同形式的污染物，其中船爆产生了最高的活性浓度和更细更可吸入的颗粒形式。这三个地点在钚和钚原子比方面是不同的，包括通过自然过程或在迁徙生物体内运输的钚。
