Centro Nacional de Aceleradores (CNA), Universidad de Sevilla, Junta de Andalucía, Consejo Superior de Investigaciones Científicas, Parque científico y tecnológico Cartuja, Thomas Alva Edison 7, 41092, Sevilla, Spain; Dpto. de Física Aplicada I, Escuela Politécnica Superior, Universidad de Sevilla, Virgen de África 7, 41011 Sevilla, Spain; Department of Health, Medicine and Caring Sciences (HMV), Linköping University, 58183 Linköping, Sweden.
Centro Nacional de Aceleradores (CNA), Universidad de Sevilla, Junta de Andalucía, Consejo Superior de Investigaciones Científicas, Parque científico y tecnológico Cartuja, Thomas Alva Edison 7, 41092, Sevilla, Spain.
Sci Total Environ. 2021 Apr 15;765:142741. doi: 10.1016/j.scitotenv.2020.142741. Epub 2020 Oct 3.
The aim of this study was to assess the potential of combining the conservatively behaving anthropogenic radionuclides U and Np to gain information on the origin of water masses tagged with liquid effluents from Nuclear Reprocessing Plants. This work includes samples collected from three full-depth water columns in two areas: i) the Arctic Ocean, where Atlantic waters carry the signal of Sellafield (United Kingdom) and La Hague (France) nuclear reprocessing facilities; and ii) the western Mediterranean Sea, directly impacted by Marcoule reprocessing plant (France). This work is complemented by the study of the particle-reactive Pu isotopes as an additional fingerprint of the source region. In the Canada Basin, Atlantic waters showed the highest concentrations and Np/U ratios in agreement with the estimated values for North Atlantic waters entering the Arctic Ocean and tagged with the signal of European Nuclear Reprocessing Plants. These results may reflect the impact of the documented releases for the 1990s. In the Mediterranean Sea, an excess of U presumably caused by Marcoule is reflected in the lower Np/U ratios compared to the Global Fallout signal in all the studied samples. On the contrary, the Pu profiles were mainly governed by the Global Fallout. The impact of Marcoule as a local source is further corroborated when comparing the temporal evolution of these ratios between 2001 and 2013. The lowest Np/U ratios observed in 2001 at the surface reflect a previous local input that is no longer observed in 2013 as it had been homogenized through the whole water column. This work presents the use of Np as a new ocean tracer. A more accurate characterization of the main sources is still needed to optimize the use of U-Np as a new tool to understand transient oceanographic processes.
本研究旨在评估结合保守行为的人为放射性核素 U 和 Np 的潜力，以获取与核后处理厂液体流出物标记的水团起源有关的信息。这项工作包括从两个地区的三个全深水柱中采集的样本：i）北冰洋，其中大西洋水携带塞拉菲尔德（英国）和拉阿格（法国）核后处理设施的信号；ii）地中海西部，直接受到马库勒核后处理厂（法国）的影响。这项工作补充了对颗粒反应性 Pu 同位素的研究，作为源区的附加指纹。在加拿大盆地，大西洋水显示出最高的浓度和 Np/U 比值，与估计值一致，表明北大西洋水进入北冰洋，并带有欧洲核后处理厂的信号。这些结果可能反映了 1990 年代有记录的释放的影响。在地中海，与全球沉降物信号相比，所有研究样本中的 Np/U 比值较低，表明可能是由于马库勒的作用导致 U 过剩。相反，Pu 分布主要受全球沉降物控制。当比较 2001 年至 2013 年期间这些比值的时间演变时，马库勒作为局部源的影响得到进一步证实。2001 年在表面观察到的最低 Np/U 比值反映了先前的局部输入，而在 2013 年不再观察到，因为它已经通过整个水柱得到了均匀化。本工作提出了将 Np 用作新的海洋示踪剂。仍需要更准确地描述主要来源，以优化 U-Np 的使用，作为理解瞬态海洋过程的新工具。
