Analysis of precipitation chemistry at a rural site in Hiroshima Prefecture, Japan

Event basis measurements of precipitation chemistry at Shobara, the rural area of the northeastern part in;Hiroshima Prefecture in Japan, during the period 1984-1988, were assessed for determining the sources of major ions, and for understanding the relation between ionic concentrations and synoptic meteorological situations. Seasonal patterns of the volume-weighted mean concentrations for major ions except H+ could be characterized by winter maxima and summer minima. Principal component analysis was performed on monthly ionic deposition. Varimax rotated three principal components accounting for approximately 90% of the total variance in the data set, could be interpreted to be acid, seasalt and soil. From back-trajectories for an event using 850 hPa winds, it was found that the volume-weighted mean concentration of non-sea-salt (nss -) SO42- for the air-mass transported from the northern part of Asian Continent was highest, and that the majority of high nss-SO42- concentrations for an event were observed for the continental air-mass under the condition of light precipitation amount. (C) 1999 Elsevier Science Ltd. All rights reserved.