Chemical Characteristics of Fog Water at Mt. Tateyama, Near the Coast of the Japan Sea in Central Japan

摘要

Measurements of the chemical composition of fog water at Murododaira (altitude, 2,450 m), on the western slope of Mt. Tateyama near the coast of the Japan Sea, were performed each autumn from 2004 through 2007. Strong acidic fogs (pH<4) containing high concentrations of nssSO_4(2-) were frequently observed in the autumn of 2005, when the air mass at Mt. Tateyama originated mainly from the polluted regions of Asia. The ratio of NO_3~-ssSO_4~(-2) in fog water was relatively high in 2004 and 2007. High concentrations of nssCa~(2+) derived from dust particles were detected in 2006. Background Kosa particles might have been predominant in the free troposphere and could have neutralized acidic fogs in the autumn of 2006. High concentrations of sea-salt components were also observed in October 2005. The sea-salt particlesrnmight have been transported from the Pacific Ocean by a strong typhoon, and significant Mg~(2+) loss was observed. Peroxides higher than 100 μM, which are seriously harmful to vegetation were sometimes detected.