Acid rain refers to the precipitation of atmospheric acidic substances into the underlying surface in the form of rain, snow, particulate matter, gaseous matter and water vapor. The first person to discover acid rain was M. Ducros, who published his article in the 1845. A journal of Pharmaceutical Chemistry confirmed its existence.

As an environmental issue, the modern scientific explanation of acid rain originated in the 1960s and 1970s from the study of regional sulfur dioxide (SO2) and nitrogen oxide (NOx) emissions by Swedish scientist Svante Oden, and north American scientist Gene Likens. Their work not only establishes the link between acid rain and emissions from coal-fired power plants and other industrial sources, but also affirms its impact on the ecological environment, such as acidification of water bodies and toxic effects on vegetation and fish.

In recent years, scientific research on acid rain has been making new progress. For example, our understanding of soil regulation and ecosystem remediation has improved significantly, revealing how plants and animals respond to low sedimentation levels and their regulatory factors, and quantifying the rate of ecosystem remediation. The regional scale of acid rain impacts, is enormous, and new observations are exploring the ability of ecosystems to recover from such large-scale disturbances. In addition, people are beginning to realize that sulfur dioxide and nitrogen oxides are closely related to the air pollutants mercury (Hg) and ozone (O3).

In conclusion to 3 important factors below.

1. 1. Acid Rain Effects on Aquatic Life

Acid rain have obvious effects on aquatic environments, such as the fish in rivers, lakes, swamps, and other plants and animals in their habitats. It will leach aluminum and other metal elements from the soil when it flows into the water by way of soil. The greater the flow of acid rain is, the more obvious the leached effect will be. Plants and animals in water can withstand acidic water and increased metal elements to a certain extent, while species or individuals with weak tolerance will withdraw from the ecosystem with the decrease of pH. In general, young individuals are more sensitive to environmental changes than mature ones. In water with a pH of 5, most fish eggs do not hatch, and adult fish cannot survive at a lower pH. Some acid lakes, for example, have no fish at all. Even if some species can tolerate progressively acidic environments, their prey can’t, and the loss of anyone link in the food chain can wreak havoc on the entire system.

2. Effects of Acid Rain on Terrestrial Plants.

Dead or dying trees are a hallmark of areas affected by acid rain. It will leach out the aluminum in the soil, thus causing harm to animals and plants. At the same time, it will cause the loss of soil minerals and nutrients, affecting the growth and development of plants. At high elevations, acid rain can exist in the form of fog or clouds and strip nutrients from plant leaves. Leaves gradually dry up and die. Plants have less area to photosynthesize and become more vulnerable to low-temperature stress at high elevations.

3. Effects on Humans.

Direct contact between humans and acid rain, such as walking in acid rain or swimming in an acid pond, does not cause serious harm to the body. However, when people are exposed to air containing pollutants that cause acid rain, such as sulfur dioxide and nitrogen oxides, their health is directly threatened. In the atmosphere, sulfur dioxide and nitrogen oxides react physicochemically to produce tiny particles of sulfate and nitrate, which can enter the body through the respiratory system. Numerous scientific studies have shown that the levels of these inhalable particles are directly related to people’s heart and lung function.  When the levels are high, the rate of sudden heart attacks and asthma will increase significantly. Nitrogen oxides can also react with other substances to form ozone (photochemical smog).