2004 Volume 53 Issue 12 Pages 1427-1434
In recent years, various pollutants are being brought from the Asian Continent to the coastal areas facing the Japan Sea, Japan and are causing the acidification of precipitation during the winter. The amounts and compositions of the pollutants vary depending on the areas. In this work, the precipitation samples were collected at nine coastal areas (Fukuoka, Hagi, Yonago, Tottori, Fukui, Ishikawa, Toyama, Kashiwazaki, and Akita) from July 2000 to June 2001; also the regional and seasonal changes of the chemical compositions of the pollutants contained in the precipitation samples were examined so as to understand the influences of long-distance transportation. As a result, the pH values of the precipitation samples collected October to February were low for all sampling locations. The concentrations of Na+ion and Cl− ion, both sea-salt ions, increased in the winter season. The concentrations of nss-Ca2 +ion, nss-SO42−ion, NO3−ion and NH4+ion, on the other hand, increased in March and April. The sea-salt ions and the acidic mixture of sulfuric and ammonium sulfate were transported by seasonal winter monsoons; however, the pollutants increasing in March and April were transported by the spring jet streams. In this study, the chemical data were also examined by principal component analysis and the features of major nine ions contained in the pollutants were extracted.
