Abstract:By using the daily observation data of acid rain from 32 stations from 2007 to 2014 as well as Yichang and Wuhan Stations during 1990-2014, we studied the variation of acid rain in Hubei Province. The results indicated that the precipitation of the region shows weak acidity and the mean pH is 4.68. The intensity has been in the trend of getting weak since 2008, maintaining a weak level between 2007 and 2014. The areas with pH less than 4.5 are located in the Three Gorges Valley, some areas of western part, the west of southeastern part, and the southern part of Hubei. The average annual frequency of acid rain and strong acid rain is 69.5% and 24.4% respectively. The frequency tends to decline while the strong acid rain shows the trend of decreasing significantly since 2009. The areas where acid rain occurs frequently are located in most southern part and the east of northwestern part of Hubei. The average annual electrical conductivity is 50.3 μs·cm-1, showing a pattern of high in central part and low in west and east part. The pH value is lower in winter than in summer while the frequency and electrical conductivity are higher in winter than in summer. The intensity of acid rain in Wuhan has been inclining to increase since 2005, retaining a strong during 2006-2012 while the electrical conductivity has a increasing trend. Both the intensity and pollution level are higher in Yichang than in Wuhan. In addition, the content of nitrogen oxides over Hubei Province tended to spread and increase. The sulphur dioxide content in Wuhan tends to decline while the nitrogen dioxide content tends to increase. Because of this change the acid rain components in Hubei may transform from sulfate to sulfate combined with nitric acid.