Online map of Chinese environmental pollution and the key management areas distribution.

Acid rain

Since the atmosphere contains a certain amount of carbon dioxide under normal conditions and dissolves in water during precipitation to form a weakly acidic carbonic acid, the normal rainwater is slightly acidic and has a pH of 5.6-5.7. Acid rain promotes acidification of rivers and lakes, attenuation of forests,reduction of grain production,and corrosion of materials.

As early as 1872, humans discovered acid rain,at the international conference in June 1982, precipitation (including rain, snow, frost, fog, sputum, sputum, etc.) with a pH of less than 5.0 was officially designated as "acid rain."In 1982, the United Nations recognized acid rain as a global environmental pollution problem.In 2000, China's acid rain distribution area has accounted for 40% of the country's land area, mainly distributed in the south of the Yangtze River.

According to the national standards for surface water,China's water quality is divided into five categories. The higher the category, the worse the water quality. According to the monitoring in January 2005, the water quality of the seven major rivers of the Pearl River, the Yangtze River, the Songhua River and the Huaihe River accounted for 28.4%. The main pollutants were permanganate,ammonia nitrogen and petroleum pollution.