Determination of the apparent complexation constants of deep groundwater humic acid with Zr (IV) by CE-ICPMS

CE-ICPMSによる地下水フミン酸とZr(IV)の見かけの錯生成定数の決定

紀室 辰伍   ; 鈴木 慎也*; 舘 幸男  

Kimuro, Shingo; Suzuki, Shinya*; Tachi, Yukio

As components of dissolved organic materials in the groundwater, humic acid (HA) is of significant importance in the environmental behavior of metals, since their mobility is influenced by the complexation with HA. Experimental data detailing the interaction of the tetravalent cations with HA is currently limited, mainly due to the assumption that the low solubility and strong hydrolysis behavior of tetravalent cations preclude the formation of complex under aqueous environmental condition. However the data is of importance for the safety assessment of geological disposal. In this study, capillary electrophoresis, coupled with inductively coupled plasma mass spectrometry (CE-ICPMS) was applied to the interaction of HAs with Zr (IV) to determine the apparent complexation constants. HA was isolated from deep groundwater at 250m depth of Horonobe, Hokkaido, Japan. As a result, the characteristic complexation property of groundwater HA was revealed by the comparative study. Additionally, the validity of equilibrium constants of groundwater HA, which were determined by other experimental methods in previous study was discussed.