Analytical Sciences

Evaluation of Ionic Pollutants of Acid Fog and Rain Using a Factor Analysis and Back Trajectories

Tetsuya ADZUHATA,*  Junko INOTSUME,* Tomoko OKAMURA,* Ryoei KIKUCHI,* Toru OZEKI,** Masahiro KAJIKAWA,* and Nobuaki OGAWA*

*Faculty of Engineering and Resource Science, Akita University, 1-1, Tegata Gakuen-cho, Akita 010-8502, Japan
**Hyogo University of Teacher Education, Yashiro-cho, Kato-gun, Hyogo 673-1494, Japan.

Fog and rain water samples were collected at the same time in the Akita Hachimantai mountain range in northern Japan from June to September in 1998 and 1999. The various ion concentrations in these samples were analyzed, and the fog droplet sizes were measured for each fog event. As the fog droplet size increased, the ion concentration decreased. The slope of log-log plots of the concentration versus the droplet size differed with the kind of ion. In order to characterize the air pollutant, moreover, these data were quantitatively analyzed by an oblique rotational factor analysis. We found that three factors were extracted as the air pollutant source: (NH₄)₂SO₄, acids (HNO₃ + H₂SO₄) and sea-salt. Combining the factor analysis with the 72 h back-trajectory at 850 hPa level, we found that the contribution of each factor varied with the transport pattern of air masses.

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