Observation reports of acid rain collected on Mt. Tateyama (2018)

Acid rain observations were done at 10 observation points from Katsuradai (660 m a. s. l.) to Murodo-daira (2450 m a. s. l.) in Mt. Tateyama and Toyama Science Museum in Toyama city. Some rain collectors set at Mt. Tateyama had been turned over by the strong wind of the typhoon during observation periods in 2018. Precipitations were increased with the rise in altitude (altitude effect). Concentrations of nitrate ions were decreased with the rise in altitude (altitude effect). However, it was observed during July to September that concentrations of non-sea salt sulfate ion increased with rise in altitude. Concentrations of ammonium ions at observation points of Mt. Tateyama were fluctuated in July and August though that concentrations showed altitude effect like as nitrate ion in September and October. These phenomena were similar to observations in 2017. Value of pH was the lowest at observation point of Murodou-daira in July and August. It was considered that the lowest pH at Murodou-daira was due to transported acidic constituent from the Asian Continent, because nitrate contribution ratio was the lowest. Number concentrations of suspended particles in precipitation collected at Oiwake (1800 m a. s. l.) from 18 to 29, August were the highest from other observation points, and sample water seemed pale yellow. These particles might be due to the Asian dust.