Europium-binding abilities of dissolved humic substances isolated from deep groundwater in Horonobe area, Hokkaido, Japan

Abstract

The binding of europium to dissolved humic substances (HSs), isolated from deep groundwater in the Horonobe area, Hokkaido, Japan, was evaluated by means of a three-dimensional fluorescence quenching technique. The Ryan and Weber model, extended by the charge neutralization model, was applied to the fluorescence quenching profiles to evaluate the conditional binding constants (K) at pH 5.0 and an ionic strength of 0.1. The K values for fulvic (FA) and humic acids (HA) in the Horonobe groundwater were comparable with each other regardless of the position of the fluorescence peaks. As compared with HSs from Lake Biwa, Aldrich, and Dando soil, the K values of the Horonobe groundwater HSs were the smallest, indicating that the Horonobe groundwater HSs have a lower affinity for the binding of europium compared to the HSs from surface environments. In addition, the results of the Aldrich-based comparison indicate that the Horonobe groundwater HSs have a lower binding affinity for trivalent lanthanides/actinides compared with other groundwater HSs obtained from different aquifer. These findings demonstrate that the characteristics and origin of deep groundwater HSs needs to be taken into consideration assessing the effects of HSs on the speciation of radionuclides in deep groundwater in geological disposal systems.

Evaluation of the Interactions between Water Extractable Soil Organic Matter and Metal Cations (Cu(II), Eu(III)) Using Excitation-Emission Matrix Combined with Parallel Factor Analysis

“…Previous studies mostly focused on the binding capacity of Eu(III) with specifically extracted fulvic acid and humic acid. The Eu(III) log K M were reported ranging between 4.90 to 5.03 for soil fulvic acid, 5.98 to 6.09 for soil humic acid, and 5.61 to 5.71 for Aldrich humic acid [ 34 ]. This study is a step forward in that Eu(III) stability constants with four components of soil WEOM were derived simultaneously ( Table 1 ).…”

Investigating the composition of dissolved organic matter in natural water in rare earth mine using EEM-PARAFAC analysis

“…Yet, despite the fluorescence intensity curves of C3 with concentration changes of U/Th, Gd/Dy, Tb/Ho, Tm/Lu and Er/Yb had a similar tendency, there was neither distinct correlation observed between fluorescence intensity and metal concentration, nor quenching effect shown in a wide range of metal concentrations, thus indicating that humic-like component was likely to absorb some metals in a considerably narrow concentration range, but in general irrelevant to the formation of new complex coordinated with rare earth elements such as Tm, Yb and Er. In a study conducted by Motoki [68] , a similar ideas might explain the reason, which proposed that the humic-like substances in the DOM of Horonobe groundwater had a lower binding affinity for lanthanides and actinides. Whereas, the interaction between dissolved rare earth metals and humic Environmental Science: Processes & Impacts Accepted Manuscript acids was described in some studies [69,70] , which discussed the influence of humic acid on the complexation behavior of lanthanides.…”

少量試料に適用可能な簡易分析法に基づく深部地下水中の溶存有機物の特性評価

“…官能基， 分子量分布などに関する分析が実施されている。 さらに，分離精製した腐植物質を用いて，放射性核種の アナログ元素であるユウロピウムとの錯形成能に関する 研究も行われている (Terashima et al, 2012) 。国外でも， 花崗岩が分布するカナダのホワイトシェル地域 (Vilks and Bachinski, 1996)や堆積岩が分布するドイツのゴア レーベン地域など (Artinger et al, 1999(Artinger et al, , 2000において， 数十～数千 L の地下水から分離精製した腐植物質の特 性が評価されている。一方，スイスのオパリナス粘土 (Courdouan et al, 2007a Christensen et al, 1996;Temminghoff et al, 1997) 。農薬や 炭化水素類など疎水性の有害有機物も，溶存腐植物質と の錯形成によって溶解度が上昇することが報告されてい る (たとえば，Chiou et al, 1986;Herbert et al, 1993 (Terashima et al, 2012;Saito et al, 2015;Kimuro et al, 2018) (たと えば，Becher et al, 1985;Knuutinen et al, 1988;Chin et al, 1994 (Terashima et al, 2012;Kimuro et al, 2018…”