Department of Chemistry and Biochemistry, University of Mississippi, University, 116 Taylor Meadows Dr, MS 38677, USA.
J Environ Radioact. 2013 Oct;124:29-36. doi: 10.1016/j.jenvrad.2013.03.002. Epub 2013 Apr 29.
Three underground nuclear tests, including the Unites States' largest, were conducted on Amchitka Island, Alaska. Monitoring of the radiological environment around the island is challenging because of its remote location. In 2008, the Department of Energy (DOE) Office of Legacy Management (LM) became responsible for the long term maintenance and surveillance of the Amchitka site. The first DOE LM environmental survey occurred in 2011 and is part of a cycle of activities that will occur every 5 years. The University of Alaska Fairbanks, a participant in the 2011 study, provided the lichen (Cladonia spp.), freshwater moss (Fontinalis neomexicanus), kelp (Eualaria fistulosa) and horse mussel (Modiolus modiolus) samples from Amchitka Island and Adak Island (a control site). These samples were analyzed for (239)Pu and (240)Pu concentration and (240)Pu/(239)Pu atom ratio using inductively coupled plasma sector field mass spectrometry (ICP-SFMS). Plutonium concentrations and (240)Pu/(239)Pu atom ratios were generally consistent with previous terrestrial and marine studies in the region. The ((239)+)(240)Pu levels (mBq kg(-1), dry weight) ranged from 3.79 to 57.1 for lichen, 167-700 for kelp, 27.9-148 for horse mussel, and 560-573 for moss. Lichen from Adak Island had higher Pu concentrations than Amchitka Island, the difference was likely the result of the higher precipitation at Adak compared to Amchitka. The (240)Pu/(239)Pu atom ratios were significantly higher in marine samples compared to terrestrial and freshwater samples (t-test, p < 0.001); lichen and moss averaged 0.184 ± 0.007, similar to the integrated global fallout ratio, whereas kelp and mussel (soft tissue) averaged 0.226 ± 0.003. These observations provide supporting evidence that a large input of isotopically heavier Pu occurred into the North Pacific Ocean, likely from the Marshall Island high yield nuclear tests, but other potential sources, such as the Kamchatka Peninsula Rybachiy Naval Base and Amchitka Island underground nuclear test site cannot be ruled out.
在阿拉斯加的阿留申群岛上进行了三次地下核试验，其中包括美国规模最大的一次。由于该岛地理位置偏远，因此对其周围放射性环境的监测极具挑战性。2008 年，美国能源部（DOE）的遗留物管理办公室（LM）开始负责长期维护和监测阿留申群岛的核试验场。2011 年进行了第一次 DOE-LM 环境调查，这是每 5 年进行一次的一系列活动的一部分。阿拉斯加大学费尔班克斯分校是 2011 年研究的参与者，它提供了来自阿留申群岛和阿达克岛（对照点）的地衣（Cladonia spp.）、淡水苔藓（Fontinalis neomexicanus）、巨藻（Eualaria fistulosa）和贻贝（Modiolus modiolus）样本。这些样本使用电感耦合等离子体质谱扇形场质谱仪（ICP-SFMS）分析了（239）Pu 和（240）Pu 浓度和（240）Pu/（239）Pu 原子比。Pu 浓度和（240）Pu/（239）Pu 原子比与该地区以前的陆地和海洋研究基本一致。地衣中的（239）+（240）Pu 水平（mBq kg(-1)，干重）范围为 3.79-57.1，巨藻为 167-700，贻贝为 27.9-148，苔藓为 560-573。阿达克岛的地衣 Pu 浓度高于阿留申群岛，这可能是由于阿达克岛的降水量高于阿留申群岛。与陆地和淡水样本相比，海洋样本中的（240）Pu/（239）Pu 原子比明显更高（t 检验，p < 0.001）；地衣和苔藓的平均值为 0.184 ± 0.007，与全球综合沉降比相似，而巨藻和贻贝（软组织）的平均值为 0.226 ± 0.003。这些观察结果提供了有力的证据，表明大量同位素较重的 Pu 输入到北太平洋，很可能来自马绍尔群岛的高产量核试验，但不能排除其他潜在来源，如堪察加半岛的里海海军基地和阿留申群岛的地下核试验场。
