Bi-weekly samples of aerosol particles, acidic gases and ammonia were collected using 4-stage filter-pack method from April 2004 to March 2017 at Tateyama Mountain area (Tateyama station, altitude: 1,180 m a.s.l.). The dominant ionic species in aerosol particles were non-sea-salt (nss) SO₄²⁻ and NH₄⁺. Long-term trends of nssSO₄²⁻ and NH₄⁺ during the period of 2005 to 2016 were −5.9 and −4.9 %/yr, respectively. NO₃⁻ concentrations were nearly unchanged. Factors contributing to seasonal variations and annual trends in these components were discussed, considering changes in emissions in Japan and China, in addition to air mass transport conditions. Observations at multiple remote sites would be useful for refining emission inventories, atmospheric chemical transport models, and further understanding of the atmospheric environment.

The granulation process of a slurry droplet containing a water-soluble polymer in a spray dryer is investigated. Although there have been many studies on the drying behavior of a single-component slurry droplet, there have been few reports for a multicomponent slurry droplet. This is due to the complexity and difficulty in evaluating the drying behavior of a multicomponent slurry droplet. Therefore, for the production of granules from multicomponent materials by a spray dryer, its operating conditions are usually determined by trial and error. To optimize the practical granule production process, the drying behavior of multicomponent slurry droplets should be studied. In this study, the drying behavior of a silica slurry droplet containing polyvinyl alcohol (PVA) is investigated. The drying behavior of a droplet suspended on the tip of a needle was observed. The effect of the volume fraction of PVA on the drying behavior and the morphology of a dried granule is studied. The effect of drying condition on the granule formation process is also investigated. As a result, the structure of dried granules was strongly influenced by PVA concentration. Segregation of PVA in the dried granules was observed. Based on the results, the drying process diagram is presented.