The damage of acid rain on forests and wildlife

Martyna Szalach

What is acid rain?

Acid rain is a broad term but it includes any form of precipitation with acidic properties, be it rain, snow, hail, fog, or dust. It is caused by the emission of sulphur dioxide and nitrogen oxides. These gases react with water, oxygen, and other chemicals in the atmosphere to form sulfuric and nitric acid, which later mix with cloud moisture, and reduce the pH of precipitation.

The compounds which produce acid rain are released from burning fossil fuels, and power plants, vehicles, and other industrial operations are their main sources. A small portion of the chemicals which cause acid rain comes from natural sources such as volcanoes, but most of them come as a result of human activities. Their emission cannot be easily stopped since burning of fossil fuels is still the primary means of generating electricity.

How does it harm the environment?

Acid rain does not exactly kill trees, but, since forests are very sensitive to changes in soil, it makes irreversible damage that may stop the growth. A healthy forest soil has a pH value of around 5.5 – 7.0, while acid rain may even have a pH of 3.0 – 4.0. The decrease of pH makes the soil more acidic, which means it loses nutrients important for the correct growth of a tree, such as calcium and magnesium. There’s also the direct leaf damage which reduces the plant’s photosynthesis capability, and makes it more vulnerable to insects, fungi, and other diseases.

The effect of acid rain can be clearly seen in aquatic environments like lakes, streams, rivers and marshes that have their own ecosystem with many different species of plants and animals all depending on each other for survival. Acid rain falls directly on these areas as it runs off the land. Some types of plants and animals are able to tolerate the acidity of the water and moderate amounts of aluminium (that is released by the acid introduced to the ecosystem). However, others that are more acid-sensitive will not survive the circumstances. Generally, the young of the species are more likely to be affected by the acidity than adult animals, but with the level of pH being high enough some adult fish die. At pH 5 most fish eggs cannot hatch and it can also form deformity in those young fish, which also struggle to take in oxygen. it all comes down to the food web collapse; the disappearance of a fish equals in the decline of the predators that feed on them. That’s why the damage is so noticeable; every harm done to a species leads to the fall of another.

What can be done about it?

As of now, acid rain cannot be easily eliminated, but there are actions to be taken in order to significantly reduce its amount. The most effective solution would be replacing burning fossil fuels with renewable energy sources. Solar, wind and hydroelectric energy reduces air pollution and the emission of gases which form acid rain. What can be done as a short term solution is the instalment of scrubbers to factories and power plant smokestacks. Once the smoke from the factory enters the scrubber, it is sprayed with a mixture that’s usually water and chemicals like powdered limestone (calcium carbonate) then the pollutants attach to the liquid, and only clean gas emerges without all the contaminants. It is also known that cars are a major source of nitrogen oxide because of the fuel burned in a car’s engine. The modern technology is able to provide catalytic converters that if used by majority of people can greatly reduce nitrogen oxide emission. A catalytic converter is a device in a car exhaust system that is able to convert the harmful gases into less harmful substances before they are released. Looking forward to the future electric and hydrogen cars will be the best choice for the reduction of acid rain as they do not directly exhaust emissions while driving. We should also think about our individual actions; saving energy, reducing electricity usage, proper hazardous waste disposal and using public

transportation does have an impact. The public awareness should be raised, as our individual actions will only work if a large group is committed. For already damaged areas ecosystem restoration is possible. While it doesn’t stop the damage from being done it still provides long-term, environmental benefits. Reforestation is an act of planting trees in areas where forest have been damaged or destroyed by acid rain. The introduction of plants and animals that are resistant to the acidic conditions is also done.