An ecosystem is a community of plants and animals that are interconnected to each other and they rely on each other for the food cycle. Everything in an ecosystem is connected. If some link is affected or harmed due to any reason, the effects are carried on to further links of an ecosystem as well. Talking about the acid rain, it is simply the acid decomposition due to the reaction of SO2 and NO2 with water and oxygen.
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Acid rain, also known as acid decomposition, includes a form of precipitation with acidic components. This includes sulfuric and nitric acids that fall on the ground from the atmosphere in both wet or dry forms. It can be anything including rain, snow, fog, dust or hail that is acidic.
Acid rain is formed due to the emission of sulfur dioxide and nitrogen oxides into the atmosphere and is further transported by wind and air currents. SO2 and NO2 react with water, oxygen and other chemicals present to form sulfuric acid and nitric acid. This does not necessarily mean that acid rain is formed with the reaction of these chemicals. Rather, a small portion of acid rain happens due to natural phenomena such as volcanoes, burning of fossil fuels, etc. The sources of SO2 and NO2 in the atmosphere are:
Manufacturing, industries and oil refineries
Vehicles and heavy equipment
Burning of fossil fuels to generate electricity. Portions of SO2 and NO2 come from electric generators.
These are carried away by carriers such as wind over long distances and even across borders. This is a problem for everyone and not only for people living in nearby affected areas. This creates adverse effects on various life forms including wildlife, aquatic life and soil. The effects of acid rain on aquatic life are seen in streams, lakes and marshes. It creates a disturbance in an ecosystem where life forms exist. Below is a brief discussion on the effects of acid rain.
The adverse effects are seen mostly in aquatic life forms and water bodies. Water flows through the soil, acidic rainwater leach, aluminium from the soil and further flows into streams and lakes. Some aquatic animals can tolerate acidic water but there are many animals which are acid-sensitive and are not able to tolerate acidic water. As a result, they die due to a decline in the pH level. Generally, the young ones in the aquatic ecosystem are adversely affected as they are acid-sensitive. At pH 5, eggs of fish cannot hatch and at a lower pH level than this, some adult fishes also lose their life.
Acid rain removes nutrients and minerals from the soil that are needed by trees to grow. Dead and decaying trees become the common sight of acid rain-affected areas. Coming to high elevations, acidic fog and clouds take away nutrients from tree foliage and make them needle-like. As a result, they do not absorb sunlight and become weak, less able to withstand freezing temperatures.
Some deposits are dry. Sometimes, dust particles become acidic as well and are called dry deposition. When acid rain and dry acidic particles fall to earth, the nitric and sulfuric acid which make the atmosphere acidic falls on monuments, buildings and statues. It damages the surface. These acidic particles corrode the metals and due to that, the paint and stone deteriorate more quickly. This finally results in costly repairing and replacement, increased maintenance costs and loss of detailing on stones and monuments and other vintage structures.
Many areas that experience acid rain do not suffer. It is because those areas can buffer the acid rain by neutralizing the acidity in the rainwater. This capacity depends upon the thickness and composition of the soil and also the bedrock. Finely textured clay soils have greater buffering capacity than coarse-textured soils.
It is described as an ongoing decrease in the pH levels of Earth’s oceans. The main cause of ocean acidification is the burning of fossil fuels. The ocean absorbs about 30 percent of the carbon dioxide that is released in the atmosphere. The issue of ocean acidification is the decreased production of shells of shellfish and other aquatic life with carbonated shells. It is also named ‘the evil twin of global warming’.
Q1. How Does Acid Rain Affect Human Health?
Ans: Walking in acid rain or swimming in acid rain affected lake is dangerous to humans. When the pollutants that cause acid rain and sulfate and nitrate particles are in the air, they cause harm to human life.
SO₂ and NO₂ react with the atmosphere to form sulfate and nitrate particles that people can inhale into their lungs. Casualties such as heart attacks and the effect on lung functions such as breathing difficulties for asthma people are interrelated with these particles. In addition to this, NO₂ emissions also contribute to ozone layer depletion which is harmful to human health. The casualties further affect visibility. NO₂ reacts with another pollutant and makes the air hazy and difficult to see through.
Q2. How Does Acid Rain Affect Plants? Are these Effects Reversible?
Ans: The impact ranges from minimal to severe, depending on the country and also the acidity of rain. Acid rain and acid fog damage the surface of leaves. It further reduces trees’ ability to withstand severe climatic conditions and hinders the process of germination and reproduction. As a result, the trees’ regenerative capability is reduced. Acid rain also depletes the supply of important nutrients to the trees from the soil. Trees affected by acid rain also have difficulty withstanding other stresses such as drought, diseases and also extremely cold weather.
This is reversible, but it takes many years. In some areas, it may even take hundreds of years to get things back to normal. Soil nutrients need to be replenished to basic levels through processes such as weathering, which takes time.