Analytical Sciences

Monitoring of the Palladium Concentration in River Water and Sediment at an Acidic Hot Spring Spa Area in Gunma Prefecture

Meichao ZHAO,*1 Nobuhiko WADA,*1,*2 Haruka SHINOZAKI,*1 Noriaki SEKO,*3 Masanobu MORI,*4 and Hideyuki ITABASHI*1

*1 Graduate School of Science and Technology, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma 376-8515, Japan
*2 Shanghai Shenglong Environment Remediation Technologies, Co., Ltd., Room 801, Building No. 1, 100 Qinzhou Road, Xuhui District, Shanghai 200235, China
*3 National Institutes for Quantum and Radiological Science and Technology (QST), Quantum Beam Science Research Directorate, Takasaki Advanced Radiation Research Institute, 1233 Watanuki-machi, Takasaki, Gunma 370-1292, Japan
*4 Faculty of Science and Technology, Kochi University, 2-5-1 Akebono-cho, Kochi 780-8520 Japan

In an effort to elucidate the deposition pathway of Pd in river sediments, we analyzed the amount of Pd in the river water and sediments of the Yukawa and Yazawa rivers, as well as in the sediments of the Shinaki dam-lake of the Kusatsu hot-spring area, which is located northwest in Gunma Prefecture of Japan. The crystal structures and elemental compositions of the river sediment samples differed significantly before and after neutralization. This was attributed to the lime input, which also affected the Pd abundance ratio obtained by the sequential extraction procedure. Additionally, the low leachability of Pd in the sediment suggested possible difficulties in its recovery. Considering the analysis of the Pd variation in the environments, it was concluded that the Pd content in the sediment of the Shinaki dam-lake was mainly supplied by the Yukawa river water inflowing the surrounding tributary rivers and hot-spring waters before neutralization, rather than the lime input.

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