Acid rain is a term that refers to rain or precipitation containing elevated hydrogen ion concentrations. The water collected from such rains is usually acidic rather than neutral. The primary cause of acid rain is the emission of nitrogen oxide and sulfur dioxide into the atmosphere. Acid rain is known to have many harmful effects on aquatic life, plants, animals, human beings, and infrastructure. Some adverse effects of acid rain are detailed in this article.
Effects on Acid Rain on Aquatic Animals
Acid rain can alter the pH value of surface water, which can cause severe damage to the aquatic life that lives in surface waters. Furthermore, acid rain can also contribute towards elevated aluminium concentration in the surface water. Excess aluminium in the water can prove fatal to fish and certain aquatic life forms. It can be noted that if the pH of the surface water drops to 5, the conditions will become inhospitable for the hatching of fish eggs. If the pH drops further, the conditions will become toxic enough to kill even adult fish. Therefore, acid rain can severely damage the biodiversity in rivers, lakes, and other bodies of water.
It can also be noted that some types of lakes containing limestone basement rocks can exhibit resilience towards acid rain. This is because the basement rocks containing carbonate minerals exhibit buffering properties and work to maintain the pH level of the water body. However, even in such ecosystems, acid rain can pose a serious threat to insect and fish life.
Effects of Acid Rain on Soil
The biological and chemical processes that occur inside soil can be seriously hampered by acid rains. For example, the microbes that cannot tolerate acidic environments fail to adapt to the lowered pH of the soil and die. The acidic environment goes on to denature the enzymes present in these microbes. Furthermore, the increased concentration of hydrogen or hydronium ions in the soil (as a consequence of acid rain) is believed to leach away certain nutrients that are essential for plant life, the most prominent example of which being magnesium. Increased hydronium ion concentration in the soil can also mobilize certain toxins in the soil, the most notable example of which being aluminium.
What is Soil Acidification?
Soil acidification can be defined as the buildup of hydrogen cations in soil, which is usually accompanied by a reduction in the soil pH. Acid rain is known to be a direct cause of soil acidification. The extent of the damage to plant life depends on the potency of the acid rain and the extent of soil acidification. For example, minor cases of soil acidification will not immediately kill plant life. However, the acidic water that is absorbed by plants growing in such soils dissolves vital nutrients and minerals before being carried away. This causes the plant to eventually die due to lack of nutrition.
Soils featuring a great extent of acidification become inhospitable for the growth of pH-sensitive plant life. In such soils, the essential nutrients are washed away at a much quicker rate, leading to the death of the plant. It can also be noted that acid rain that falls on the leaves of plants can cause the drying of the waxy leaf cuticle. Acidic water can also affect the ability of a plant to conduct photosynthesis by destroying chloroplast organelles.
Ocean Acidification as a Consequence of Acid Rain
Although the impact of acid rain on oceanic ecosystems is not as severe, it can have several negative effects on oceanic life forms. For example, a drop in the pH of the ocean water (commonly known as ocean acidification) can make it difficult for certain species of coastal life to create their exoskeletons, which is essential for their survival. Therefore, ocean acidification can contribute to a loss of biodiversity.
It is also important to note that ocean acidification can cause severe disturbances in the ocean’s food web or food chain. The loss of biodiversity as a consequence of acid rain is often accompanied by an immediate disturbance in the local food chain. For example, the exoskeletons of corals (which are made up of limestone) can be dissolved by acid rain, which may greatly affect their population in the affected area. This, in turn, will affect the population of their immediate predators.
Effects of Acid Rain on Human Beings
Although acid rain is not directly harmful to human beings, the gases that cause acid rains are. Sulfur dioxide and oxides of nitrogen, when present in large concentrations in the atmosphere, can cause respiratory problems in human beings. Furthermore, the fine particulate matter in the air can also contribute towards several medical conditions in humans such as bronchitis and asthma.
Acid rain also has an effect on the infrastructure created by humans. For example, buildings, statues, and historic monuments that are made up of marble, limestone, or other rocks containing calcium carbonate are susceptible to damage from acid rains. This is because the acids in the acid rain react with the calcium carbonate in the structures to form gypsum, which is then flaked off the structure. It can be noted that acid rain can severely diminish the aesthetic qualities of statues and monuments.
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