14:00 〜 14:15
[BCG10-02] 段階的間隙水抽出による岩石間隙中の反応-輸送現象の不均質性の評価
キーワード：間隙水、溶解、移流
Heterogeneity of dissolution/precipitation and solute transport in rock pores has been drawing attention in recent years. This phenomenon has been often studied using numerical calculation, but direct analysis of pore water is important to know what is actually occurring in pores. However, most previous studies have analysed the composition of bulk pore solution and it is difficult to discuss the detail of reactive-transport behaviour in pores using the bulk composition. In the present study, an experimental technique to sequentially extract pore water by applying various gas pressures to wet sample was used. With this technique, pore water can be extracted for each pore radius, which provides information on the heterogeneity of reaction and transport in pores. In the experiment, pure water was first passed through a sandstone core to induce dissolution in pores (flow-through reaction), then pore water was extracted for each pore size and solute concentrations were measured. The result of the experiment showed that the concentrations of Na, Ca, Mg, and Si increased with decreasing pore radius and that the concentration increases of Ca, Mg, and Na were greater than that of Si. Qualitatively, this result can be explained by a numerical model of the advection and dissolution in a single tube for different pore radii. However, the observed concentration increases were significantly greater than the model calculation, and it seems possible to evaluate the extent of the mixing of solutions in narrow pore and large pore by comparing the model calculation and experimental result.