An analysis on spatial/temporal evolution of acid rain in China (1993-2006) and its causes

The acid rain observation network of China Meteorological Administration (CMA) was first established in 1989, with 22 stations. It maintained 85 to 88 stations from 1993 to 2005, After more sfations established in 2006 and 2007, the station number of the network has rapidly increased to 294. Considering the continuity of data, the data used in this paper is the 14-year observations of the 88 stations' network from 1993 to 2006. Based on the latest 14 years observations of the acid rain network, statistics and analysis results show that the acid rain dominated in the vast regions south of the Yangtze River, and the limited presence of acid rain zone was also observed in the northern part of the country. The 14-year acid rain data indicate that an expanding tendency of acid rain zones was obvious especially in northern China, but it remained virtually unchanged in southern China. And the most severe acid rain polluted zone gradually moved from Southwest China to Central China and the central part of South China. As far as acid intensity of rain is concerned, 1993-1998 was the period of severest acid rain, the intensity of acid rain slightly reduced in 1999-2002, increased again in 2003-2006, and reached the average acidity of the period of 1993-1998 by the end of 2006.In addition, the rain acidity in northern China increased markedly. For the causes of the rain acidity situation in China, this paper explains it in terms of the sulfur dioxide emissions and the monitoring data of rainwater chemicals.