Acid rain, a global environmental concern, is a form of precipitation with high levels of nitric and sulfuric acids. These acids fall to the ground, causing a wide range of harmful effects on the environment and living organisms, including humans.
The Science Behind Acid Rain
Acid rain is not purely acid falling from the sky but is, in fact, rainfall or atmospheric moisture mixed with elements and gases, making it more acidic than usual.
Formation of Acid Rain
Acid rain forms when sulfur dioxide (SO2) and nitrogen oxides (NOx) released into the atmosphere react with water, oxygen, and other substances to form airborne sulfuric and nitric acid. These gases are primarily produced by human activities, such as burning fossil fuels, which are often carried for hundreds of miles in the atmosphere by winds into rural areas.
When acid rain reaches the Earth’s surface, it flows across the surface in runoff water, enters water systems, and sinks into the soil.
pH Levels of Acid Rain
Normal rain is slightly acidic, with a pH of 5.6. However, acid rain generally has a pH between 4.2 and 4.4. The pH scale ranges from 0 to 14, with 7 being neutral. Acid substances have a pH less than 7, while alkaline (or base) substances have a pH greater than 7.
Devastating Effects of Acid Rain
The impacts of acid rain extend from the natural environment to human-made structures and can even affect human health.
Acid Rain and Aquatic Ecosystems
Acid rain poses a significant threat to aquatic environments, such as streams, lakes, and marshes. It can make waters more acidic, resulting in more aluminum absorption from soil, which is carried into lakes and streams. The heightened acidity and aluminum levels can be harmful to aquatic life, including crayfish, clams, fish, and other wildlife.
Acid Rain and Forests
Forests, particularly those at higher elevations, are severely affected by acid rain. The acid deposits rob the soil of essential nutrients such as calcium and cause aluminum to be released in the soil, which makes it hard for trees to take up water. The damage to trees and plants can also make them less able to withstand freezing temperatures, insects, and disease.
Acid Rain and Built Structures
Acid rain contributes to the corrosion of surfaces exposed to air pollution and is responsible for the deterioration of limestone and marble buildings and monuments. The acidic particles corrode metal and cause paint and stone to deteriorate more quickly. They also dirty the surfaces of buildings and other structures such as monuments.
Acid Rain’s Impact on Human Health
While acid rain itself is not harmful to humans, the pollutants that cause acid rain can be. SO2 and NOx, as well as sulfate and nitrate particles, can be inhaled into the lungs and have been linked to health issues such as heart attacks in people with increased heart disease risk and breathing difficulties for people with asthma.
Battling Acid Rain: Potential Solutions
The only way to combat acid rain is by curbing the release of the pollutants that cause it. This means burning fewer fossil fuels and enforcing air-quality standards.
Regulatory Measures
In the U.S., for example, the Clean Air Act of 1990 targeted acid rain, putting in place pollution limits that helped cut sulfur dioxide emissions by 88 percent between 1990 and 2017.
Technological Innovations
Promoting innovation and new technologies aimed at optimizing energy consumption and developing renewable energy can also be a significant step towards reducing the emission of pollutant gases.
Planting Trees
Planting trees can absorb polluted air, helping to mitigate the effects of acid rain. Trees absorb CO2, a significant contributor to acid rain, and release oxygen, helping to reduce the overall acidity of the atmosphere.