抄録
Positive matrix factorization (PMF) was applied to daily wet deposition data from three stations in Japan to find the source profiles from which the precipitation samples are constituted. For most ions more than 90% of the weighted variation was explained with 4 factors. The factors are characterized by the following compounds: strong acids (H2SO4 and HNO3), (NH4)2SO4, NaCl, and CaSO4. The anion-cation balance was fairly good in the factors. Based on the chemical compositions of the factors, a time series of the factor contributions, and the results from trajectory analysis, the factors are considered to represent sea salt, soil, (NH4) 2SO4 and acidity. Although the total nss-SO4 wet deposition amount decreased in the last 7 years at Wajima station, the contributions of the (NH4) 2SO4 factor to nss-SO4 wet deposition were fairly constant (ca.50%). The acidity seemed to be controlled by the neutralization by soil particles.
