Recent Characteristics of Fog Water Chemistry at Mt. Tateyama, Central Japan: Recovery from High Sulfate and Acidity.

Measurements of chemical compositions in the fog water at Murododaira (36.6°N, 137.6°E, altitude 2450 m), Mt. Tateyama, on the Sea of Japan side of central Japan, were performed mainly in autumn, and the characteristics of chemical climatology before 2010 and after 2017 were compared. Strong acid fogs that were sometimes detected before 2010 were not observed after 2017, and the pH of the fog water increased. Since 2017, the concentration of SO₄²⁻ in the fog water has decreased significantly, and it has been observed that the fog water tends to be purified. There was no significant difference in the concentrations of ionic components except H⁺ and SO₄²⁻ between before 2010 and after 2017. The nssSO₄²⁻/NO₃⁻ ratio in the fog water was high before 2010 but has decreased in recent years. The large reduction in SO₂ emissions in China in the 2010s has had a major impact on the fog water chemistry at Mt. Tateyama. [ABSTRACT FROM AUTHOR]