Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan.
Water Res. 2013 Mar 15;47(4):1570-84. doi: 10.1016/j.watres.2012.12.017. Epub 2012 Dec 27.
The saline groundwater collected at a depth of about 500 m in Horonobe, Japan, where an underground research laboratory (URL) has been built, is rich in saline (Na 4900 ppm, Cl 7600 ppm), iodine (42 ppm), and methane gas. We analyzed the colloids and ions of this groundwater mainly by employing a size exclusion chromatography (SEC) coupled on-line to ultraviolet-visible (UV-Vis) detection and inductively coupled plasma mass spectrometry (ICP-MS) technique and focused on the speciation of uranium and iodine, both of which are of particular importance for radioactive waste disposal. For this purpose, the groundwater sample was introduced to SEC columns after being passed through a 0.45 μm filter but without further pretreatment, such as isolation of colloids. The chromatographic profiles obtained with two different SEC columns were compared. This study revealed that uranium present in the groundwater at several tens of ppt was associated with low molecular weight silica species with neutral charge. The silica species were virtually free of metal elements such as Na, K, Mg, Ca, and Al. This study also found that almost all of the iodine in the groundwater was iodide (I(-)). The groundwater contained an unidentified organic colloid that was not a carrier for the radioactive waste-relevant elements Se, Sr, I, Cs, Th, and U.
在日本幌延地下研究实验室（URL）所在地，采集到深度约为 500 米的高盐地下水，其富含盐分（Na 4900 ppm，Cl 7600 ppm）、碘（42 ppm）和甲烷气体。我们主要采用尺寸排阻色谱（SEC）与紫外-可见（UV-Vis）检测和电感耦合等离子体质谱（ICP-MS）技术在线联用的方法，对这种地下水的胶体和离子进行了分析，重点研究了铀和碘的形态，这两者对于放射性废物处置尤为重要。为此，地下水样品在经过 0.45μm 过滤器过滤后，但未进行胶体分离等进一步预处理，就被引入 SEC 柱中。比较了使用两种不同 SEC 柱获得的色谱图。本研究表明，地下水中存在的数十 ppt 浓度的铀与带中性电荷的低分子量硅物种有关。这些硅物种实际上不含 Na、K、Mg、Ca 和 Al 等金属元素。本研究还发现，地下水中几乎所有的碘都是碘化物（I(-)）。地下水含有一种不明的有机胶体，它不是放射性废物相关元素 Se、Sr、I、Cs、Th 和 U 的载体。
