Variation of pH in atmospheric precipitation in cities of Jilin province

Through statistical analysis on data of atmospheric precipitation samples of 8 cities from 1992 to 1997, this paper discussed temporal and spatial variations of pH in atmospheric precipitation in Jilin Province, China. Monitored pH value in the 8 representative cities was converted into hydrogen ion consistency and average consistency was calculated by weighting precipitation, then mean pH value was calculated according to average hydrogen ion consistency. Results show that atmospheric precipitation of cities in Jilin Province is basically neutral, but in Tumem and Hunchun cities atmospheric precipitation is seriously acid. The average pH value of atmospheric precipitation of the eastern cities of Tumen and Hunchun in many years is 5.12 and 5.38 respectively, and the atmospheric precipitation acidity in the two cities is quite serious with the extreme low pH is 3.91 and 4.28 respectively. Most of the acid precipitation occurred in summer and autumn seasons in the 8 monitored cities, so that the low pH value of atmospheric precipitation occurred in summer and autumn seasons and high pH value occurred in winter and spring seasons. The temporal and spatial variations of pH in atmospheric precipitation in Jilin Province are attributed to both local sources and peripheral sources, and are related to both natural and artificial factors.