Tetsuya Adzuhata

Cloud droplet size dependence of the concentrations of various ions in cloud water at a mountain ridge in northern Japan

Acid precipitation is one of the global environmental problems affecting terrestrial and aquatic ecosystems. Our research group has recently studied the acid precipitation in Hyogo and Akita Prefectures in Japan, combining chemical analysis of ions with analysis of meteorological conditions, and has analyzed the source of pollutants by Ž . factor analysis Ozeki et al., 1995, 1997; Ogawa et al., 1998a,b . It is known that fogrcloud water is significantly more acidic and has higher concentrations of chemical Ž . components than rain water e.g., Waldman et al., 1982; Hosono et al., 1994 . The mechanism of uptake of ion components into cloud droplets, especially for the difference between ions, is not completely understood. Cloud water and rain water samples were collected at the Hachimantai mountain range in Akita Prefecture in northern Japan to obtain information on the mechanism of uptake of ion components into cloud droplets. The chemical composition of the cloud water was analyzed and compared with that of the rain water. The relationship among ion concentrations in the cloud water and droplet size was examined Ž X X Cloud water samples were collected along the mountainside 39856 N, 140851 E, . Ž . 1465 m, a.s.l. of Mt. Mokkodake 1578 m, a.s.l. , a mountain ridge in the Hachimantai Ž . Ž range. A passive fog sampler Okita, 1961 with a cylindrical Teflon wire screen Model . FWP-500, Usui Kogyo Kenkyusho was exposed during the period from August to Ž . September 1997. Rain water samples were collected at Akita City Akita University

Evaluation of ionic pollutants in cloud droplets at a mountain ridge in northern Japan using constrained oblique rotational factor analysis

The scavenging of aerosol particles by precipitation and fogrcloud plays an important role in the distribution and concentration of pollutants in the atmosphere. Our research group has recently studied the acid precipitation in Hyogo and Akita Prefectures in Japan, combining chemical analysis of ions and analysis of meteorological Ž . Ž conditions, and has analyzed the ionic pollutants salts by factor analysis Ogawa et al., . 1998a,b, 1999a,b; Ozeki et al., 1995, 1997 . In general, it is known that fogrcloud water is significantly more acidic and has higher concentrations of chemical components than Ž . rain water e.g., Waldman et al., 1982, Hosono et al., 1994, Ogawa et al., 1999a,b . But the mechanism of uptake of ion components into cloud droplets, especially for the Ž difference between ions, is not completely understood. In our previous works Ogawa et . al., 1999a,b , cloud water and rain water samples were collected at the Hachimantai mountain range in Akita Prefecture in northern Japan to obtain information on the mechanism of uptake of ion components into cloud droplets. We obtained the information about relationship among ion concentrations in the cloud water and droplet size Ž . Ogawa et al., 1999a,b . In this work, we tried to analyze the seasonal change of ionic pollutants in cloud water due to a variation of mesoscale precipitation system and their dependence upon the cloud droplet size using constrained oblique rotational factor analysis, which has

Chemical Characterization of Acid Fog and Rain in Northern Japan Using Back Trajectory and Oblique Rotational Factor Analysis

Fog/cloud and rain water were collected at the mountainside of Hachimantai range in northern Japan and rain water was also collected at Akita City in order to investigate the air pollutant scavenging mechanism. The concentrations of various ions in these samples were analyzed, and the fog drop size and the wind direction were measured at each fog event. The fog at Hachimantai range had a very high total ion concentration, and was considerably acidified by non sea salt (nss-) SO42− and NO3−, compared with the rain at Akita and all sites in Hachimantai range. Using the oblique rotational factor analysis, three factors were extracted as the air pollutants; A: (NH4)2SO4+H2SO4, B: sea salts+HNO3+H2SO4, C: NH4NO3+OH−. These salts are well-known as the cloud condensation nuclei (CCN). Combining the factor analysis with the 72h back trajectory at 850hPa level, the contribution of Factor A was closely connected to the long-range transportation of anthropogenic or natural aerosol in air masses of continental origin.

Relationships between chemical compositions and meteorological conditions for fog and rain at Hachimantai range, and rain at Akita city in Japan.

Acid fog and rain samples were collected at Mountain range of Hachimantai and at Akita City in Japan. Various ion concentration of these sample were analyzed using an ion chromatography and pH meter. The NO3- concentration of rain at Akita increased gradually year to year. The fog water had a high concentration of various ions compared with the rain. The highest concentration was observed in the weather chart of high pressure on Japan Island. The fog water had a low concentration for various ions in autumn compared with those in spring, so that this result agreed with the fact that the autumn sky is clear and clear in Japan.