Influence of Asian long-range eolian dust on chemical components and inorganic dust deposits of rainwater in northeast Japan
1998
Inoue, K. (Iwate Univ., Morioka (Japan). Faculty of Agriculture) | Hamaura, H. | Hiradate, S. | Kasai, O.
Five snow samples collected on Mt. Hachimantai (1400 m a.s.l.) in the months of May and June from 1991 to 1996 contained significant amounts of eolian dust. Fifty-four rainwater samples were collected at Morioka from Jan. 17, 1992 to April 27, 1994 and at Fukaura from Sept. 28, 1992 to Feb. 3, 1995; areas located in Northeast Japan. The pH values, concentration of chemical components, and amount of eolian dust in the rainwater samples were determined. Fifteen percent and 27% of the rainwater samples from Morioka and fukaura, respectively, were acid rain. About 76 and 57% of the inorganic dust deposits in the rainwater samples from Morioka and fukaura, respectively, were dominated by a 20 mu-m fraction and their depositions were marked from winter to spring, suggesting a strong influence of Asian long-range eolian dust. The annual deposition of nssSO4(2-) and nssCa(2+) in rainwater was 4.5 and 4.0 meq m(-2) in Morioka and 6.2 and 7.1 meq m(-2) in Fukaura, respectively. The chemical compositions of eolian dust deposits in the rainwater samples were compared with chinese loess and Hachimantai eolian dust in snow deposits. These deposits were characterized by almost the same chemical, physical and mineralogical properties. Sulfate in the Morioka rainwater is transported from China. In addition, the relatively low E factors of SO4(2-) of Japanese rainwater samples were partially influenced by sea salt, especially in the winter season. The present results suggest that the rainwater samples in Northeast Japan are strongly influenced by Asian long-range eolian dust
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