[O-08] Poster presentations by senior high school students

[O08-P05] Light scattering caused by sulfur particles makes Shirata river blue.

*Tomita Kazuma¹, Ryosuke Yoshida¹ (1.Shimoda high school)

Keywords:Shirata river, Izu, sulfur, colloid, water, geosite

The Shirata river flows from Mt. Amagi on the Izu Peninsula to Higashiizu Town in Shizuoka Prefecture, and this river possessed a sulfur mining site during the Edo period. We hypothesized that the Sirata river looks blue because of light scattering caused by colloidal sulfur particles, and have been trying to verify it for two years. Last year (JpGU 2021), we reported that the pH of the Sirata river was acidic and that the clay from the Sirata sulfur mine contained 30 percent (mass ratio) of sulfur. This year (JpGU 2022), we present three data to prove that sulfur particles make the Sirata river blue. The first data is the analysis of sulfide and sulfate ions (H₂S and SO₄^2-) in the water of the Sirata river. The second data is the quantification of blueness at each point of the Sirata river. The third data is the absence of blue components except sulfur particles in the water of the Sirata river.