Abstract
The pH of meteoric water was determined for 995 and 736 samples respectively in Tokyo (1973-1980) and Tsukuba (1980-Apr. 1984). The mean value of pH during the observation period was 4.5 both in Tokyo and Tsukuba. It was found that the distribution of the hydrogen ion concentration in meteoric precipitation is of the lognormal type. The percentages of occurrence of acid rain (pH<4) were 26% in Tokyo and 10% in Tsukuba, while those of the precipitation amount were 7.0% in Tokyo and 4.3% in Tsukuba. The apparent constancy for many years of pH of meteoric water in Tokyo may be due to the buffering action of calcium carbonate suspension against nitric acid.
