Dark clouds

A very beautiful metaphor, the opportunity to explain to children the phenomenon of acid rain. Acid rain is one of the consequences of air pollution from the use of sulfur-rich fossil fuels such as oil, coal and natural gas;工厂、供暖和道路交通是主要原因。 The disastrous effects for biodiversity are numerous. The increased acidity of soils and rivers endangers many animals and plants lose the mineral nutrients necessary for their development.