The Trouble with Acid Rain

Acid rain occurs when sulfur dioxide (SO2) and nitrogen oxides (NOx) are emitted in the atmosphere and interact with water, oxygen and other chemicals to form sulfuric and nitric acids.  Once these compounds mix with water, they fall to the ground in the form of precipitation. Most of the SO2 and NOx that causes acid rain comes from the burning of fossil fuels and vehicles/heavy equipment.

While normal rain has a pH around 5.6, acid rain falls between 4.2 and 4.4 on the pH scale. Normal rain is slightly acidic because carbon dioxide dissolves into it forming a weak carbonic acid.

The effect of acid rain on trees. Photo from Ludwig Werle/Getty images

The effect of acid rain on trees. Photo from Ludwig Werle/Getty images

Acid rain can have many adverse effects on the environment, especially on water bodies such as streams, rivers, lakes and wetlands. This acidity makes its way to the aquatic life that inhabit the water and can make the environment toxic through the leaching of aluminum from the acid rainfall. Those species that are acid-sensitive are at risk as the pH of the water becomes more acidic. According to the U.S. Environmental Protection Agency, a pH of 5 inhibits most fish eggs from hatching and lower pH levels can even kill off adult fish species.

Acid rain damages forests as well by harming the tree foliage and releasing aluminum in the soil. The aluminum impedes the trees’ abilities to soak up water from the ground. Likewise, the acidity also removes important nutrients from the soil that trees need for growth.

The environments that do not endure the serious detrimental effects of acid rain have a buffering capacity. A buffering capacity is a resistance to changes in pH and allows an ecosystem to neutralize the acidic rainwater. The capacity depends on factors regarding the soil and underlying bedrock of the region but can highly benefit the ecosystem as the effects of acid rain are lessened.

Acid rain is not a commonly discussed topic, however, it is one we need to address. There are some natural causes of acid rain such as volcanoes and lightning but the most common causes are caused by humans. Stopping acid rainfall can only be accomplished by decreasing the emissions that cause it in the first place. Through a decrease in industrial practices, and a greater importance placed on renewable energy sources rather than fossil fuels, we can work to halt acid rain and restore the health of our environment.


Marissa Rollman