SO2 Emission and Acid Rain Change in Chongqing

Based on the acid rain data measured at Shapingba weather station in Chongqing from 1993 to 2007 and the emission data of SO₂ in Chongqing, Guizhou and Sichuan, the acid rain change trend and its relationship with SO₂ emission were analyzed. The results indicated that in the past 15 years, the change trend of the pH value of the precipitation in Chongqing changed between 3.8 and 4.5. The annual variation trend was increasing. In the past 15 years, acid rain (pH<;5.6) frequency in Chongqing was high and increased with fluctuate. The frequency of acid rain exceed relatively strong intensity (pH<;4.5) had greatly annual change, which was mainly between 30% and 80%. There was relativity between SO₂ emission and pH value in Chongqing. The pH value was influenced mainly by SO₂ emission besides other factors such as meteorological condition. SO₂ emission in Guizhou and Sichuan could have some influence to acid rain in Chongqing. In which Guizhou could be the main distal contamination emission source area.