Acid Rain

How Acid Rain Affects Organisms in Aquatic Biomes

Through the advancement of technology, the issue of the air surrounding the earth might have been one of the most often matters to be brought up and discussed among scientists and engineers. Acid rain is one of the more serious environmental problems and it is closely related to the air pollution. Nowadays, it has affected large part of US, Europe and Canada. People start to be concerned about acid rain since it is getting worse in the passed years. The effect of the acid rain most often leads to another bad effect. For example, the acid rain will cause the lake and streams to be acidic. Thus, it will also affect the ecosystem inside the water.

Acid rain is one form of air pollution that is caused by automobiles, certain industrial operations, and electric power plants that burn fossil fuels like coal, natural gas, and oil. These processes emit the gases sulfur dioxide and nitrogen oxides into the atmosphere, where they combine with water vapor in clouds to form sulfuric and nitric acids.

Although researches had been made and people start to know about acid rain, the fact that we live in a world that uses fossil fuel in almost all the electricity that powers modern life causes the acid rain to be emitted more and more into the atmosphere. Nowadays, the air pollution had reached to a point where the idea of reducing acid rain is not a subject of individual and scientists anymore; instead it is also our responsibility as people that live in the same world to know more about this matter and learn ways to help prevent it from getting worse.

The term “Acid Rain” is a broad term used to describe several ways in which acid falls out of the atmosphere. A more precise term is acid deposition. There are two parts of acid deposition, wet and dry. Acidic rain, fog, and snow are some common example of wet deposition. As these acidic form flows to the ground, it affects most of their surroundings including plants and animals. The strength of the effects depends on many factors including how acidic the water is, the chemistry of the soil involved, and the types of animals and plants and their reliance to the water. Dry deposition on the other hand, refers to acidic gases and particles. The wind is what usually blows these acidic particles onto building, cars, home, and trees. When rainstorm is present, it can wash the dry deposited gases and particles from trees and other surfaces. However, when that happens, the runoff water adds that acid to the acid rain, making the combination more acidic and dangerous than the falling rain alone.

The effect of acid rain varies from one area to another area. They can damage forest and soils, fish and other living things, materials, and even human health can also be affected. The most observable environmental effect of acid rain has been the loss of fish in acid sensitive lakes and streams. Since many species of fish are not able to survive in acidic water; thus acid rain can cause fish and other animals living inside an affected lake or water to be killed and can even completely eliminate fish species. The following two pictures depict how acid rain can harm fishes as well as pollute streams.

The majority lakes and streams have a pH level between six and eight. Some lakes are naturally acidic even without the effects of acid rain. For example, Little Echo Pond in New York has a pH level of 4.2. There are several routes through which acid rain can enter the lakes. Some chemical substances exist as dry particles in the atmosphere, while others enter directly into the lake in a form of precipitation. Acid rain that has fallen on land can be drained through sewage systems leading to lakes. Another way acids can enter the lake is by spring acid shock. At the time acid snow melts in the spring, the acids in the snow seeps into the ground and some run-off the ground and into lakes.

Spring is a vulnerable time for many species since this is the time for reproduction. The sudden change in pH level is dangerous because the acid can cause serious deformities in their young. Generally, the young of most species are more sensitive than the elders. However, not all species can tolerate the same amount of acid. For example, frogs may tolerate relatively high levels of acidity, while snails are more sensitive to pH changes.

Sulfuric acid in polluted precipitation interferes with the fish's ability to take in oxygen, salt, and nutrients. For freshwater fish, maintaining osmoregulation, the ability to maintain a state of balance between salt and minerals in the organism's tissue, is essential to stay alive. As shown in the figure in the next page, acid molecules cause mucus to form in their gills preventing the fish to absorb oxygen well. Furthermore, a low pH level will throw off the balance of salt in the fish's tissue. Calcium levels of some fish cannot be maintained due to the changes in pH level. This causes a problem in reproduction: the eggs are too brittle or weak. Lacking calcium causes weak spines and deformities in bones. Sometimes when acid rainfall runs off the land, it carries fertilizers with it. Fertilizer helps stimulate the growth of algae because of the amount of nitrogen in it. However, because of the increase in the death of fish the decomposition takes up even more oxygen. This takes away from surviving fish. In other terms, acid rain does not help aquatic ecosystems in anyway.

In general, acid rain affects lakes and streams in two ways, which are chronic and episodic. Chronic, a long-term acidification results, form years of acidic rainfall. It reduces the alkalinity or buffering capacity and increases the acidity of the water. Chronic acidification may reduce the levels of nutrients such as calcium, which, over time, may weaken the fish and other plants and animals in an aquatic ecosystem. Episodic acidification is a sudden jump in the acidity of the water. The heavy rainstorm could produce an episodic acidification. It also happens in the spring, because the sulfates and nitrates will concentrate in the lowest layers of a snow pack. In the spring, when that snow melts, it will be more acidic than normal. Episodic acidification can cause sudden shifts in water chemistry. This may lead to high concentrations of substances such as aluminum, which may be toxic to fish.

The fossil fuels that have been burned by humans could increase the chemical balance of the ocean which is also known as the seawater acidity levels. According to researchers from UW, the National Oceanic and Atmospheric Administration’s Pacific Marine Environmental