In order to facilitate the future research of aerosol physics and chemistry by using high altitude platforms in Japan, past observations on precursors and trace gases and aerosol species at the summit of Mt. Fuji are reviewed from the viewpoint of effects by the local wind circulation, which is distinctive meteorology to the mountain range. Although the observed concentrations of aerosol precursors and trace gases were influenced somewhat by the diurnal pattern of the up- and down-slope winds, amplitudes of the diurnal variation in their concentrations were generally smaller than those obtained at other mountains, such as Mauna Loa. For the case of 222Rn observation, 24 h moving averages of the 1 h data gave an excellent accordance with the simulated 1 day average by a chemical transport model. Those facts suggest that the precursors and trace gases data obtained at the summit of Mt. Fuji could characterize the free tropospheric air quality covering an extensive region over the Far East. On the other hand, mass as well as number concentrations of aerosol species exhibited its considerable susceptibility to the diurnal change of mountain and valley winds during summer. With the aid of advanced observation of mountain meteorology and the use of the latest simulation model with grids of a few hundred meters, atmospheric physical structures of the lower and middle troposphere in various scales and accompanied aerosol chemistry as well as its long-range transport and mixing processes should be investigated at the high altitude platforms including Mt. Fuji.
On the mountain side of Mt. Oyama, fog is frequently formed and pH of fogwater is low due to nitric acid formed from NOx. Recently, the concentration of fog components has increased because of a decrease in liquid water content (LWC) , which may be caused by a decrease of SPM as the condensation nuclei. The concentration of fog components becomes high when LWC is low, and acid fog events with fog water pH lower than 3.5 occur for about 20 % of fog duration at the mountainside (680 m a.s.l.) every year. It has been observed that the throughfall amount increased with an increase in altitude, although the precipitation amount does not depend on the altitude. It is caused by the fog deposition, which may be dominated by the fog formation frequency and the deposition rate of fog droplets depending on the wind velocity. The deposition of air pollutants on the canopies is caused by many path ways, rain, fog, gas, and aerosol. Deposited hydrogen ion is exchanged with metal ions in the leaves, and the application of simulated acid fog to the seedlings of fir, cedar, and beech in an experimental chamber showed that the amount of base cations leaching from leaves increased with decreasing pH of the applied acid fog solutions. Fir and beech seedlings were severely damaged by the long term application of simulated acid fog. Acid depositions on the surface soil is large in Mt. Oyama, and the soil has been acidified for recent years.
Mt. Norikura (36.1 °N, 137.5 °E, summit 3,026 m a.s.l.) is a high elevation site that has been utilized for atmospheric observations since the 1960s. This paper highlights the observation on number-size distributions of atmospheric aerosol particles performed at Mt. Norikura (2,770 m a.s.l.) in September 2001 and August-September 2002. First, we present the number-size distributions of the aerosol particles observed during nighttime (free tropospheric aerosol) , which was analyzed in terms of the relation to the air-mass transportation pathway, the cumulative precipitation amount in the air mass for the last 24 h, and the local precipitation rate. Results of the analysis suggest that the precipitation scavenging is an important process to modify the particle size distribution by decreasing the particle concentration. Considering the data for the air masses without the experience of precipitation scavenging before the arrival, the data suggests that air-mass transportation pathway is an important controlling factor especially for Aitken mode particle concentration. Next, we describe the relationship between occurrence of nucleation mode in particle number-size distributions and air-mass exchange associated with the diurnal variation of local wind system. The nucleation mode particles were observed in the mixed layer air transported by upslope valley wind but never observed in the free tropospheric air transported by down slope mountain wind, which suggest that new particle formation occurred in the mixed layer but never did in the free troposphere just above the mixed layer.
Aerosol and cloud in the free troposphere play an important role in the climate change. We provide the information, in this paper, on the physical and chemical properties of atmospheric aerosol in high mountain region at Mt. Tateyama area with respect to their temporal and spatial variability. This area is located in the center of Honshu island, Japan, near the Toyama bay on the coast of the Sea of Japan. We conducted the measurements of the chemical composition of fog waters as well as other related observations in the Mt. Tateyama area in autumn. It was found that the acidic fog observed at Murododaira (2,450 m) was not mainly due to nitrate but sulfate suggesting the remote source of the acidic matter. Also conducted was the analysis of snow layer sampled from Murododaira since 1970's. The piled layers of snow exhibit the chronology of transport and deposition of acidic matters, Asian dust and other pollutants from the continent to the Toyama area. Furthermore, we measured the aerosol optical properties by using a sky radiometer in the city of Toyama and Mt. Jodo (2,847 m). These measurements revealed that the aerosol optical thickness has a significant vertical variability at the top of the mountain.
Mt. Happo is located in the Japan Alps. The observation of aerosol has been conducted around the Happo-ike mountain lodge and acid rain monitoring station, which is one of the monitoring sites in Acid Deposition Monitoring Network in East Asia (EANET) , at an altitude of 1,850 m. Effects of long range transportation of air pollutants from sources in East Asia were investigated there. In this paper, we describe the characteristics of the monitoring points and the history of various observations together with a part of observational results. Monitoring of ozone concentration first started at the mountain lodge in 1985 and other observations such as aerosol, acid deposition, gases and meteorological parameters followed. Airborne particulate matters were collected by a low-volume air sampler from 1990 and after 1997 a tape air sampler was added. Intensive observations collaborated with National Institute for Environmental Studies were conducted four times in the period from 1991 to 1995, and the behavior of acidic and oxidizing substances were investigated. Volcanic gases, from Miyakejima volcano eruptions, were observed in 2000.
In order to reveal the contribution of valley wind to the concentration of aerosol at the top of Mt. Fuji from the lower areas, field observations were performed at the summit station (3,776 m a.s.l.) , 7.8th shelter (3,255 m a.s.l.) , and Tarobo shelter (1,300 m a.s.l.) on the mountain in the summer of 2007. We quantitatively evaluated the amount of aerosols transported from the lower areas to the top of Mt. Fuji by a valley wind using the concentrations and the meteorological parameters measured at each station. During the observation when a valley wind blew up, the concentration at the 7.8th shelter first rose and then that at the summit station increased for several days. A model analysis of transported aerosols showed that the transport of aerosols by a valley wind takes place with their dilution or supply. A model analysis based on particle dilution for the transported aerosols with the diameter of about 400 nm to which the contribution of supply is small showed that about 85 % of aerosols at the summit are transported from the lower areas. These results were also confirmed by the chemical analysis of aerosols sampled at the summit and Tarobo shelter during the observation in the summer of 2008.
We reviewed the effect of lunar dust (regolith) on humans from technological and biological point of views. In physicochemical properties of lunar dust, hazard-related factors are that silicon occupies about 50 % in composition, and that fibrous materials and nanoparticles are included. Animal exposure studies have been performed using a simulant of lunar dust, and it was speculated that the harmful effect of simulant lies between crystalline silica (positive control) and titanium dioxide (negative control). Fibrous materials may not have low solubility judging from the component. The nanoparticle in lunar dusts may have harmful potentials by the components. In microgravity, the deposition of particles with less than 1 μm in human lung did not decreased, but the deposition of particles with diameter of several μm decreased linearly with reducing the gravity. In microgravity the functions of macrophage including phagocytosis were suppressed. These data on the deposition of particles and the function of macrophage suggested that fine and ultrafine particles may be accumulated in the lung in microgravity. The researches on lunar dust and microgravity are preliminary and very much limited, therefore it is necessary to perform lots of researches in this field.