Peroxide concentrations in fog water at mountainous sites in Japan

Measurements of peroxide concentrations in fog water were conducted near th e summit of Mt. Norikura (altitude, 2770m) in central Japan, and at the mid slope of Mt. Oyama (altitude, 680m), southwest of the Kanto Plain. The conc entrations of peroxide at Mt. Norikura, far from industrial regions, ranged from 3 to 120 muM during the summer and early autumn in 1993. The potentia l capacity for SO, oxidation appears to be very high near the summit of Mt. Norikura. Analysis of the chemical composition of three-stage size-fractio nated fog water samples collected at Mt. Norikura showed that the concentra tions of peroxide were apparently independent of droplet size, whereas the concentrations of chemical constituents mainly derived from secondary aeros ols and the acidity were higher in smaller droplets. Peroxide concentration s in fog water were low (< 5 muM) at Mt. Oyama, located near heavy industri al areas, and lower than those in rain water sampled simultaneously (0.2-33 mu M). Especially, peroxide was scarcely detected in strongly acidic fogs (< 0.2 mu M). Peroxide might have been decomposed by SO2 (S(IV)) oxidation in the aqueous-phase.