Fog is formed frequently in mountain areas and is apt to cause forest decline, because fog has highly concentrated air pollutants and is readily acidified. The elucidation of the fog characteristics in the areas has been limited because successive observation is difficult in mountains. We have observed wet depositions and meteorological conditions at Mt. Oyama, located about 56 km west–southwest of Tokyo. The mountain meteorology was observed with various devices and the fog frequencies dependent on the altitude were roughly estimated from the meteorology of the base of the mountain. The precipitation amount of the throughfall at the mountain is much larger than that of rainfall, and the large deposition on the canopy is caused by not only fog but also drizzle. Fog and drizzle sample was collected by string-type passive fog collector, PFC, and the meteorological data relating to the collecting rate of PFC sample were observed. PFC samples were affected by rainwater under windy condition and the contribution of the rain to the PFC sample volume was evaluated to be about 30% in average. The sampling rate of PFC was related to the precipitation intensity of throughfall, and it became possible to estimate the air pollutants deposition on the canopy via wet deposition by the analysis of the samples of PFC as well as rain. The fog and drizzle may cause several times larger deposition of air pollutants on the canopies than the deposition via rain at high mountain forest.

由于雾气中的空气污染物浓度高，容易酸化，山区雾气形成频繁，容易造成森林衰退。由于山区难以连续观测，因此对该地区雾特征的阐明受到限制。我们在山上观察到湿沉积和气象条件。小山，位于东京西南偏西约 56 公里处。使用各种设备观测山地气象，根据山脚的气象粗略估计取决于海拔高度的雾频率。山上贯通的降水量远大于降雨量，树冠上的大量沉积不仅是雾，还有毛毛雨。雾和毛毛雨样品由串式被动雾收集器 PFC 收集，并观察与PFC样品收集率有关的气象数据。PFC 样品在大风条件下受到雨水的影响，雨水对 PFC 样品体积的贡献估计平均约为 30%。PFC的采样率与直通降水的降水强度有关，通过对PFC和雨水样品的分析，可以通过湿沉降来估计空气污染物在冠层上的沉积。雾和毛毛雨在树冠上造成的空气污染物沉积可能比高山森林通过雨水沉积大数倍。PFC 样品在大风条件下受到雨水的影响，雨水对 PFC 样品体积的贡献估计平均约为 30%。PFC的采样率与直通降水的降水强度有关，通过对PFC和雨水样品的分析，可以通过湿沉降来估计空气污染物在冠层上的沉积。雾和毛毛雨在树冠上造成的空气污染物沉积可能比高山森林通过雨水沉积大数倍。PFC 样品在大风条件下受到雨水的影响，雨水对 PFC 样品体积的贡献估计平均约为 30%。PFC的采样率与直通降水的降水强度有关，通过对PFC和雨水样品的分析，可以通过湿沉降来估计空气污染物在冠层上的沉积。雾和毛毛雨在树冠上造成的空气污染物沉积可能比高山森林通过雨水沉积大数倍。