[B-CG03] Earth and Planetary Science Frontiers for Life and Global Environment

[BCG03-P01] Desorption behavior of heavy metals from contaminated soils:A surface complexation modeling

*Natsumi Takeda¹, Keisuke Fukushi², Baasansuren Gankhurel¹, Akihiro Okuyama¹ (1.Kanazawa University, 2.Institute of Nature and Environmental Technology Kanazawa University)

Keywords:Surface complexation modeling, heavy metal, desorption

It is reported that soil at Kamegai mine in Toyama Prefecture contains heavy metals at a level that greatly affects human health. In this study, we conducted desorption experiments from the soils mainly composed of goethite collected at Kamegai mine under various environmental conditions to elucidate the desorption behavior of heavy metals. The results of the experiments showed that the desorption concentration of Pb, Cu, Cd and Zn decrease as the pH increased. When the pH increased further, these elements re-desorbed. Pb and Cu had the minimum desorption concentration at pH7, and Cd and Zn had the minimum concentration at pH8 and above. The behavior of this desorption concentration decrease can be explained by the mineral surface charge. However, the behavior of re-desorption at high pH can be explained by the chemical species. This mechanism could be explained thermodynamically by using surface complexation modeling. Finally, when modeling was performed under the experimental conditions based on the JIS standard conducted in the previous research, the results exceeded the environmental standard for a wide range of pH, and even for natural water condition. Therefore, proper treatment is required when using land in the Kamegai mine area.