Abstract
Rainfall was collected in bulk by means of a bulk type filtered acid precipitation sampler at 5 different collection points. Setagaya, Okutama, Atsugi, Ninomiya and Fuji in the Kanto area. The collection began in September 1996 and lasted for one year.
Concentrations of Na+, NH4+, K+, Ca2+, Mg2+, Cl-, NO3+ and SO4+ ions in the rain-fall as well as pH values were measured by means of Ion chromatography and pH meter. The mean value of pH in rainfall was between 4.47 and 5.36.
An investigation was carried out to evaluate the ratio of Ca2+, Mg2+, Cl- and SO4+ ions that originated in sea salt to the total ions in the acid rain, based on the assumption that all Nat ion are derived from sea salt.
Therefore, the average contribution percentage of ss-K+, ss-Ca2+, ss-Mg2+, ss-Cl- and ss-SO4+ ions originated from sea salt (ss-) were 11.39, 1.76, 44.45, 70.45 and 11.98% espectively.
Volume-weighted precipitation of sea salt ions decreased with an increase in distance from North latitude 35 degrees, except from Setagaya. Setagaya was highly polluted by human work sources. Because it is estimated that sea salt ions were captured and then concentrated in the polluted air. Volume-weighted precipitation of non sea salt ions were etagaya>Atsugi>Fuji, inomiya> Okutama In order of amount.
