Spatial differences of chemical features of atmospheric deposition betweenrainy season and winter in the areas facing to the Japan Sea, Japan

Atmospheric deposition was collected using filtrating bulk samplers at 32 s ites in the areas facing to the Japan Sea(AFJS) from April 1991 to March 19 94. The data were analyzed for winter(January and February) and the rainy s eason(June and July) when the climate is just the opposite. The AFJS was ge ographically divided into five areas, that is western Tohoku(WT), Hokuriku( HR), eastern San-in(ES), western San-in(WS) and northern Kyushu(NK). WT, HR and ES receive more precipitation than other regions in winter. H+ deposit ions increase in winter except NK. This is mainly due to high winter H+ con centrations. In spite of large amounts of precipitation in WT, HR and ES in winter, nss-SO42- concentration was nearly equal to the average throughout Japan. Namely, nss-SO42- depositions in these areas were nearly twice the national mean. In WT, HR and ES, nss-Ca2+ concentrations in winter are lowe r than the average of the whole country(less than the half). This may be th e cause of the lower potentials of neutralization and the higher remaining acid concentrations in WT, HR and ES than NK and WS. (C) 1998 Elsevier Scie nce Ltd. All rights reserved.