Do you know "acid rain"

Acid rain is acidic precipitation that causes air pollution. It is generally believed that PH5.6 when atmospheric precipitation is in equilibrium with carbon dioxide gas is the natural acidity of precipitation, which is used as a criterion to judge whether it is acidified or not. When the PH value of precipitation is lower than 5.6, precipitation is called acid rain.

Why does precipitation turn sour? This is mainly the result of air pollutants being absorbed by clouds in the sky and constantly reacting in raindrops to form acidic substances. Acid rain does great harm to the environment and is called the "killer" from the air. It not only kills forests, but also affects the decrease and death of crops and freshwater organisms, and it will corrode buildings and all facilities exposed to the air, historical relics, and even endanger human health and the ecological balance of cities.

At present, acid rain pollution accounts for about 30% of China's land area, and it is developing at an alarming rate in some areas. The direct losses caused by agriculture and forests in Sichuan, Guizhou and Guangdong provinces alone amount to1800 million yuan every year. The main source of acid rain in China is a large number of sulfur dioxide pollutants discharged in the process of energy consumption with coal as the main source. Therefore, in order to control acid rain pollution, we must first control the total amount of sulfur dioxide emissions.