Abstract
In order to identify the characteristic chemical composition of falling snow in Shinjo, we collected snow samples during four winter seasons (from 1999/00 to 2002/03), and measured their pH, EC and major ionic components. More than 70 ％ of the snow samples were acid snow with pH less than 5.0.The average range of pH was from 4.7 to 4.9 in each year. The concentration of sea-salt components (Na+ and Cl-)tended to rise in the strong northwest winter monsoon. The nssSO4 2- concentration of samples were slightly higher than NO3- concentration. The nssCa2+/NO3- ratios suggested that NO3- mainly originated from nearby areas, while nssSO4 2- was transported from the Asian continent. The nssCa2+ concentration were increased depending on the influence of airborne yellow sand. Moreover, falling snow in Shinjo became more acidified year to year during 1991 to 2003, and we determined it was highly possible that snow acidification was influenced mainly by elevated NO3- concentration.
