Ion components in dustfall samples collected with deposit gauge in Kitakyushu City in the period from October 1987 to September 1989 were analyzed to discuss the deposition and seasonal variation of SO
42- and Ca
2+. High deposition of excess-Ca
2+(ex-Ca
2+) were observed in the inductrial area, and the amount decreased with increasing distance from the area. Depositions of ex-SO
42- showed a similar tendency. Deposition of ex-SO
42- increased during spring and summer, and decreased in winter months. Deposition of ex-Ca
2+ increased in the early spring (Fig.2). The positive relationship between the precipitation amount and deposition of ex-SO
42- was found (Fig.3). On the other hand, deposition of ex-Ca
2+ increased with increasing precipitation amount of up to 100-150 mm, but the deposition gradually decreased with precipitation amount over those values (Fig.3).
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