Hamilton Terry F, Martinelli Roger E, Kehl Steven R, McAninch Jeffrey E
Center for Accelerator Mass Spectrometry, CMELS, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94551-0808, USA.
J Environ Monit. 2008 Oct;10(10):1134-8. doi: 10.1039/b806077k.
We have determined the level and distribution of gamma-emitting radionuclides, plutonium activity concentrations, and 240Pu/239Pu atom ratios in tissue samples of giant clam (Tridacna gigas and Hippopus hippopus), a top snail (Trochus nilaticas) and sea cucumber (Holothuria atra) collected from different locations around Enewetak Atoll. The plutonium isotopic measurements were performed using ultra-high sensitivity accelerator mass spectrometry (AMS). Elevated levels of plutonium were observed in the stomachs (includes the stomach lining) of Tridacna clam (0.62 to 2.98 Bq kg(-1), wet wt.), in the soft parts (edible portion) of top snails (0.25 to 1.7 Bq kg(-1)), wet wt.) and, to a lesser extent, in sea cucumber (0.015 to 0.22 Bq kg(-1), wet wt.) relative to muscle tissue concentrations in clam (0.006 to 0.021 Bq kg(-1), wet wt.) and in comparison with previous measurements of plutonium in fish. These data and information provide a basis for re-evaluating the relative significance of dietary intakes of plutonium from marine foods on Enewetak Atoll and, perhaps most importantly, demonstrate that discrete 240Pu239Pu isotope signatures might well provide a useful investigative tool to monitor source-term attribution and consequences on Enewetak Atoll. One potential application of immediate interest is to monitor and assess the health and ecological impacts of leakage of plutonium (as well as other radionuclides) from a low-level radioactive waste repository on Runit Island relative to background levels of fallout contamination in Enewetak Atoll lagoon.
我们测定了从埃尼威托克环礁不同地点采集的巨蛤（大砗磲和库氏砗磲）、马蹄螺（大马蹄螺）和海参（黑海参）组织样本中发射伽马射线的放射性核素水平及分布、钚活度浓度和240Pu/239Pu原子比。钚同位素测量采用超高灵敏度加速器质谱法（AMS）进行。在大砗磲的胃（包括胃黏膜）中观察到钚水平升高（0.62至2.98 Bq kg(-1)，湿重），在马蹄螺的软组织（可食用部分）中（0.25至1.7 Bq kg(-1)，湿重），以及在较小程度上，海参中（0.015至0.22 Bq kg(-1)，湿重），相对于蛤类肌肉组织浓度（0.006至0.021 Bq kg(-1)，湿重）以及与之前鱼类中钚的测量值相比。这些数据和信息为重新评估埃尼威托克环礁海洋食物中钚的膳食摄入量的相对重要性提供了基础，也许最重要的是，表明离散的240Pu239Pu同位素特征很可能提供一个有用的调查工具，以监测埃尼威托克环礁的源项归因及其后果。一个直接相关的潜在应用是监测和评估鲁尼特岛上低水平放射性废物处置库中钚（以及其他放射性核素）泄漏相对于埃尼威托克环礁泻湖沉降污染背景水平对健康和生态的影响。
