Air polution in Kagoshima city and Sakurajima caused by volcanic ash from Mt. Sakurajima (part IX) : investigation from April 1, 1986 through March 31, 1987

The volcanic ash from Mt. Sakurajima was collected together with rain water monthly from April 1986 to March 1987 at 14 locations in Kagoshima city and 7 locations in Sakurajima. After the samples had been filtered, the residue was dried and weighed, and the filtrate was analyzed for SO_4^{2-}, Cl-and water-soluble matter as well as for pH. The amount of sulfur oxides absorbed on a PbO_2-candle were measured at the same locations (except for 2 locations of Sakurajima) as with ashfall measurement. The average monthly ashfall at the 14 locations in Kagoshima city was 211 ton/km^2 and that at 7 locations in Sakurajima was 2,056 ton/km^2. Both values were half, or less than half of those values observed in the last fiscal year. The falling weights of SO_4^{2-}, Cl^- and water-soluble matter for this fiscal year were generally lower than those for the last year. However, the frequency of acidic rain was considerably higher than that for the last year. The average amount of sulfur oxides absorded on the PbO_2-candle in Sakurajima for this fiscal year was much less than the corresponding average for the last year