Institut de Radioprotection et de Sureté Nucléaire (IRSN), PSE-ENV, SRTE/LRTA, SEREN/LEREN, SAME/LMRE, BP 3, 13115 Saint-Paul-lez-Durance, France.
Institut de Radioprotection et de Sureté Nucléaire (IRSN), PSE-ENV, SRTE/LRTA, SEREN/LEREN, SAME/LMRE, BP 3, 13115 Saint-Paul-lez-Durance, France.
Sci Total Environ. 2018 Dec 1;643:40-51. doi: 10.1016/j.scitotenv.2018.06.074. Epub 2018 Jun 21.
Tritium (H) and Carbon-14 (C) are radionuclides of natural (cosmogenic) origin that have also been introduced into the environment by humans since the middle of the last century. They are therefore not compounds that have only recently been released into the environment and they do not pose a recognized health threat due to their low radiotoxicity. However, they hold an important place among current concerns because they are being discharged into the environment by the nuclear industry in large quantities compared to other radionuclides. Those both radionuclides partly integrate organic matter during metabolic processes (i.e., photosynthesis) leading to organically bound forms that can be found in sediments. Organically bound tritium (OBT) analyses carried out on the sediments of the Rhône and its tributaries indicate a significant and historical tritium labelling of sedimentary particles all along the Rhône river, as well as in several northern tributaries, in particular the Ognon and the Tille rivers (tributaries of the Saone), the Doubs River and the Loue River (a tributary of the Doubs) and the Arve river. The recorded levels (10 to over 20,000 Bq/L) are very likely to be related to the presence of synthetic tritiated particles (technogenic tritium), which were used in the past in watchmaking workshops. Although overall contamination levels decrease from north to south in the Rhône watershed and fade over time, particularly due to the radioactive decay of tritium, this contamination source of technogenic tritium in the Rhône watersheds is currently still not negligible. Carbon-14 analyses show that the Rhône sediments generally display C levels close to the atmospheric reference values (231 Bq·kg of C in 2015) or even lower in most of cases, and show sporadic and weak labelling near nuclear facilities. The low C levels in the Rhône sediments are most likely related to the solid contributions from tributaries draining areas that are rich in fossil organic matter, and therefore devoid of C. In the Rhône watershed, the presence in solid particles of tritium in a form organically bound to synthetic compounds and of petrogenic (fossil) organic carbon, can potentially alter the apparent assimilation rates to the food chain of these two radionuclides.
氚（H）和碳-14（C）是天然（宇宙成因）来源的放射性核素，自上世纪中叶以来，人类也将它们引入环境中。因此，它们不是最近才释放到环境中的化合物，由于其低放射性毒性，它们不会构成公认的健康威胁。然而，由于它们在核工业中与其他放射性核素相比大量排放到环境中，因此它们在当前关注中占有重要地位。这两种放射性核素在代谢过程中（即光合作用）部分整合到有机物中，导致可以在沉积物中发现有机结合的形式。对罗纳河及其支流沉积物进行的有机结合氚（OBT）分析表明，整个罗纳河以及几个北部支流（特别是奥格农河和蒂勒河（索恩河的支流）、多河和卢河（多河的支流）以及阿尔沃河）的沉积物颗粒都有明显的历史放射性氚标记。记录的水平（10 到 20,000 Bq/L 以上）很可能与合成氚化粒子（人为氚）的存在有关，过去在制表车间中使用过这些粒子。尽管罗纳河流域的总体污染水平从北到南逐渐降低，并且随着时间的推移逐渐消失，特别是由于氚的放射性衰变，但目前罗纳河流域人为氚的这种污染来源仍然不可忽视。碳-14 分析表明，罗纳河沉积物的 C 水平通常接近大气参考值（2015 年为 231 Bq·kg 的 C），在大多数情况下甚至更低，并且在靠近核设施的地方显示出零星的弱标记。罗纳河沉积物中 C 水平较低的原因可能是，来自富含化石有机物的支流的固体物质贡献较大，因此缺乏 C。在罗纳河流域，合成化合物有机结合形式的氚和源自岩石的（化石）有机碳的固体颗粒中的存在，可能会改变这两种放射性核素进入食物链的表观同化率。
