Acid rain has been documented as a threat to the environment. How does acid rain impact the environment? We will examine the effects of acid rain on Earth’s natural processes and the possible damages to the living world.
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Acid rainA precipitation that is abnormally acidic because it contains dissolved pollutants, which can cause great environmental damage, can be defined as “precipitation that is dangerously acidic”. Normal rain will have a pH between 5.5 and 4.0. Acid rain, however, has a pH of around 4.0 due to its dissolved sulphur dioxide and nitrogen oxides. These are acidic pollutants.
How does acid rain affect the atmosphere?
Most of the sulphur dioxide, nitrogen oxides and other gases are emitted by humans through human activities like burning fossil fuels or exhaust fumes from vehicles. A small amount of the emissions are produced by natural processes like decaying vegetation or volcanic activity.
These sulphur dioxide, nitrogen oxide and other sulphur dioxide emissions diffuse into the atmosphere. They then dissolve in water droplets in clouds, forming sulphuric and nitric acids respectively. These cloud droplets can then be transported in the wind and formed acid rain by wet deposition. Alternately, some pollutant particles might not be dissolved in cloud water and form acid rain. Instead, they may return to Earth’s surface through dry evaporation.
Source: US Environmental Protection Agency
How does acid rain affect the water cycle?
Acid rain is precipitation that is released from clouds and reaches the Earth’s surface. Most of it is transported to rivers or lakes by surface runoff, groundwater flow, and a small fraction goes to lakes and rivers. This is where it mixes with existing water, increasing the acidity of the water. This drop in pH is especially dramatic for large amounts of rainfall entering a small water body.
Acid rain can also fall from the atmosphere as acid-snow when it is cold enough. This type of acid deposition can be especially damaging to the natural environment because it will accumulate on ground and then melt to release large amounts of acidic water into surrounding landscapes.
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How does acid rain affect soil and rock?
Limestone rocks are prone to erosion due to acid rain. The calcium carbonate found in limestone reacts to acidity, producing calcium sulfurate or calcium citrate, both of which are soluble products. This reaction also releases carbon dioxide gases. The soluble products will eventually be transported into rivers, where they may cause aquatic life damage. The reaction will also release carbon dioxide into the atmosphere, which will cause and exacerbate global warming.
Acid rain also causes a decrease in pH, which can affect the concentrations of various heavy metals present in the water. Acidic environments allow for more aluminium to be released from soil into the water, while calcium is less easily available and its concentration in the water is lower. The water’s concentration may rise, making it toxic to certain aquatic organisms. Conversely, the ecosystem could be affected if certain metals are reduced.
Source: Lennard & Goddek (2019).
How does acid rain affect plant growth and ecosystems?
Acid rain directly affects living organisms. Species that live in confined environments are particularly vulnerable because they can’t migrate to less acidic water. While some species can tolerate high pH changes, others cannot. For example:Many local fish populations were decimated by the rise in acidity in a number of lochs in Galloway in Scotland in the 1900s.
Acid rain can also cause damage to the waxy outer layer of plant leaf leaves. This makes them less able to photosynthesise effectively and increases their mortality risk. A high level of acid rain sensitivity can cause the initial loss or destruction of key species within an ecosystem. This could lead eventually to the death of other species which are dependent upon the key species for their survival.
Simulation of leaf damage caused by acid rain Source: Vernica et al. (2020)
How Acid Rain Affects Human Health
Acid rain and the pollutant particles of nitrogen oxide and sulphur dioxide that it is formed from have been linked directly to eye irritation, heart disease, and asthma. The formation of acid rain is not the only problem. Tropospheric Ozone, which is known for causing respiratory problems in people, is also a known side effect.
Source: Britannica
Answering the question about acid rain and its effects on the environment will reveal a variety of environmental problems as well as impacts on humans. To avoid further damage from acid rainfall, it is essential to identify the main sources and reduce their emissions in order for them to be less harmful. To reduce emissions from polluting sectors like electric utilities and vehicles, it is necessary to use cleaner technologies that can remove pollutant gases from the environment and prevent them from causing any environmental damage.
Featured Image by: Flickr (CC BY -NC-ND 2.0)
