Abstract
The properties of initial (until 2 mm) and succeeding rainfall at Ikoma-shi in Nara prefecture, where located in the middle of Osaka-shi and Nara-shi, were investigated over 1993 to 1995. The appearance percentages of initial and succeeding rainfall below pH 5.6 were approximately 93% and 75%, respectively. The contents of Cu2+ (μg/L) in the rain water increased as pH becomes lower. Although the relationship between pH and the electric conductivity showed some scatter, the electric conductivity increased exponentially as pH becomes lower. As a results of the determination of main ion species containing in the rain water of 1995, the contents (mol/L) in the initial rainfall were 2 to 3 times compared with these in the succeeding rainfall for Na+, K+, NH4+, C1-, NO3- and also were 4.5 to 5.0 times for Mg2+, Ca2+, SO42-. The linear relationship was recognized between pAi (=-log ((NO3-) + (SO42-))) which shows the hydrogen ion concentration corresponding to the molar concentration of NO3- and SO42- and the logarithm of the electric conductivity (logλ), but was not recognized between pAi and pH. The occurrence source of Na+ and Clin the rain water suggested to be due to the sea salt.
