The eruption of the Miyake-jima Volcano (34.08¿N, 139.53¿E) in the Izu Islands, Japan, 180 km SSW of Tokyo, began on 8 July 2000. A substantial amount of NH3 gas was found to be emitted from the Miyake-jima Volcano together with SO2 gas and that geochemically significant quantities of aerosol particles composed of ammonium sulfate form in the plume. Through the use of satellite images, the additional atmospheric deposition of ammonium sulfate caused an increase of phyto-plankton in the nutrient-deficient region south of the Kuroshio. The emission of volcanic gases from the Miyake-jima has likely been modifying the marine air quality as well as the open ocean ecosystem over parts of the western North Pacific for the past several years.