ION CONCENTRATION AND ACID DEPOSITION IN MOUNTAINOUS REGION OF JAPAN

Acid deposition on plains has been widely monitored. However, depositi on monitoring in mountainous regions has been much less common due to the difficulty of access. We monitored acid deposition at eight sites in mountainous regions in Japan from June till October in 1992. The pH of deposition samples obtained from mountainous regions was in the ra nge from 4.7 to 5.3, slightly higher than that measured in samples fro m plains. The relative abundances of anions and cations were mainly ns s-SO42>NO3->nss-Cl- and K+>NH4+>nss-Ca2+. The [NO3-]/[NO3-]+[nss-SO42- ]) ratio was 0.1 similar to 0.2 at sites of higher than 1500 m and gre ater than 0.3 at sites lower than 1500 m altitude. Ion concentrations in acid deposition in mountainous regions were lower than those in pla ins, however rainfall in mountainous regions was greater than that in plains. So total ion deposition in mountainous regions at some sites w as similar to that in plains.