Summer Ionic Pollution of Easterly Cold Wind (Yamase) Fog at the Hachimantai Mountain Range in Northern Japan

To make clarify the pollution mechanism of the fog which occurs in Yamase, which is a local weather phenomenon in summer of cold wind blown from the edge of the Okhotsk Sea high-pressure region to the northern Pacific coast ofJapan, fog water samples were collected at Akita Hachimantai in 2003. The Yamase fog pollution level is lower than that of usual weather conditions. The total ion, nss-SO sub(4) super(2-) and NO sub(3) super(-) concentrations of fog water in Yamase are lower than those of other wind directions. Therefore the pH of fog water in Yamase is higher than other cases and the Yamase fog is not acidified. The component ratio of NH sub(4) super(+) of fog water in Yamase is higher than that of nss-SO sub(4) super(2-) because fog droplets would take up gaseous NH sub(3) generated from the ground surface, rather than (NH sub(4)) sub(2)SO sub(4).