Acid Rain In The Environment

Introduction

When pollutants from the atmosphere, such nitrogen oxides and sulphur oxides, interact with precipitation and descend with the rain, acid rain results. Wet and dry acid deposition are the two different forms of acid deposition. Humans are harmed by acid rain, which also aggravates allergies and skin conditions and is thought to contribute to about 550 annual premature deaths. Additionally, historical structures like buildings and monuments are destroyed by acid rain. Therefore, it is vital to take action to stop acid rain. Sulphur dioxide and nitrogen oxide emissions can be reduced, cleaner fuels can be used instead, waste gases can be treated, and acids can be neutralized to prevent acid rain.

Acid Rain: What Is It?

• As the name suggests, the most basic definition of acid rain is the precipitation of acid in the form of rain.

• Acid rain is a term used to describe highly acidic water droplets that form in the atmosphere as a result of air pollution, especially the excessive levels of sulphur and nitrogen created by vehicles and industrial processes.

• Wet and dry acid deposition are the two different forms.

• Wet deposition refers to any form of precipitation that deposits acids on the surface of the planet after removing them from the atmosphere.

• In the absence of precipitation, detrimental dry deposition of particles and gases attaches to the ground through dust and smoke.

Acid Deposition

• Acidic deposition, which can take many different forms, includes acid rain.

• Wet deposition and dry deposition are the two primary divisions of them.

• Wet deposition is the term used to describe rain, sleet, snow, or fog that has been more acidic than typical.

• Acidic gas and particles are referred to as dry deposition.

• Around half of the acidity of the atmosphere is returned to the globe as a result of dry deposition.

Types Of Acid Deposition

Wet Deposition

• Wet deposition is what we most usually associate with acid rain.

• Rain, snow, fog, and hail fall to the ground along with sulfuric and nitric acids that have formed in the sky.

• Because this acidic water seeps into the ground and washes over it, it has an effect on a wide variety of plants and animals.

• Rain-out, which occurs when particles are absorbed into cloud drops that fall to the earth, and washout, which occurs when materials beneath a cloud are pulled down by rain or snow that falls, are the two ways that precipitation removes gases and particles from the atmosphere.

Dry Deposition

• In areas with dry weather, the acid chemicals are deposited through dry deposition.

• The gases and acidic particles may immediately settle on surfaces (such as water, vegetation, or structures), or they may react while being carried through the atmosphere to generate larger particles that could be harmful to human health.

• Dry gas and particle depositions on these surfaces can be eliminated by runoff from rainstorms.

• The amount of acidity in the air that settles as a dry deposition on the soil in a particular area depends on how much rain falls there.

Sources Of The Substances That Cause Acid Rain

• Acid rain is mostly caused by sulphur and nitrogen. Both artificial and natural factors contribute to their release into the atmosphere.

Sulphur

• Natural Sources of Sulphur: Sulphur is a naturally occurring element that may be found in seas and oceans. It is also released during volcanic eruptions and biological processes like the breakdown of organic matter in the soil.

• Artificial Sources: Burning coal produces 60% of the world's sulphur dioxide (SO2), while petroleum products contain 30% of it.

• Sulphur is released into the atmosphere during the smelting of metal sulphide ores to obtain pure metals.

• As a byproduct of the industrial production of sulfuric acid in the fertilizer, chemical, and metallurgical industries, sulphur is also emitted into the atmosphere.

Biological Sources of Nitrogen

• Lightning, volcanic eruptions, and biological processes are some of the natural causes of nitrogen release.

• Microorganism breakdown, nitrogen fixation, absorption, mineralization, nitrification, and denitrification are some of the biological processes.

• Anthropogenic Sources: Man-made reasons for the release of nitrogen include forest fires and the combustion of oil, coal, and gas.

Formic Acid

• Forest fires cause biomass to burn, which releases formaldehyde (HCHO) and formic acid (HCOOH) into the atmosphere.

• Large levels of formaldehyde are photo-oxidized, creating formic acid in the environment.

• These three substances are the principal ones responsible for the acidity of rain in the atmosphere.

• The main causes of the acidity of rain in the atmosphere are these three chemicals.

Acid Rain: Characteristics

Composition

• The two potent acids that make up acid rain are nitrogen oxide and sulphur dioxide.

• When these two gases interact with the oxygen and water in the atmosphere, sulfuric and nitric acids are produced.

• Thus, sulphur dioxide and nitrogen oxide are the primary chemical components of acid rain.

• Only a small amount of the SO2 and NOX that causes acid rain comes from volcanic eruptions or other natural sources, such as burning fossil fuels.

Acidity

• A scale that is used to quantify acidity is the pH scale. This scale's range is 0 to 14.

• 0 is the least acidic number, whereas 14 is the most alkaline.

• Unpolluted rain would have a pH of between 5 and 6.

• As a result of increased pollution from sulphur dioxide and nitrogen oxide, the pH of the air can become as acidic as 4.

• Acid rain can travel great distances in the atmosphere.

Common Features of Acid Rain Regions

Areas that are susceptible to acid rain attacks share the following traits:

• They are primarily found in the industrialized belt of the northern hemisphere.

• They are typically highland or mountainous areas that get a lot of rain and snow.

• Due to the abundance of water, they have a number of lakes and streams in addition to another area that is covered in flora.

• Because they are uplands, they usually feature thin soils and glaciated bedrock.

Difference Between Normal And Anthropogenic Acidified Lakes

Particulars	Normal Acidified Lakes	Anthropogenic Acidified Lakes
Colour	By humic compounds, a brown to yellow colour is produced.	Due to lower primary productivity, the water is very clear.
Transparency & Organic Carbon Concentration	Transparency is low and dissolved organic carbon concentrations are significant.	The transparency is excellent while the amounts of dissolved organic carbon are low.
Buffering And pH	High buffering but low pH.	Poor buffering is prevalent.
Aquatic Life	Aquatic life is abundant.	Several of the more delicate taxa, including blue-green algae, some bacteria, snails, mussels, crustaceans, mayflies, and fish, either experience a drop in population or even get eliminated.

Acid Rain's Effects On The Soil

• Hydrogen ions in the soil interact with nutrient cations like potassium and magnesium, causing nutrient leaching and rendering the soil infertile.

• A decline in soil organism respiration occurs along with this.

• An increase in soil ammonia caused by a reduction in other nutrients slows the rate of decomposition. The soil's nitrate content is also seen to be lower.

• Since Indian soils are typically alkaline and have a considerable capacity for buffering, acid rain has less of an impact there.

Effects On Animals

• Documentation of acid rain's impacts on wildlife is difficult because they are frequently imperceptible.

• However, it has been demonstrated that acid rain has a range of negative direct and indirect effects on the reproduction and survival of wildlife populations.

• It has been suggested that acid rain can have an indirect impact on wildlife by allowing metals bound to soil and sediment to be released into the aquatic environment, where animals, like birds, that eat in that habitat may consume harmful compounds.

• It has been suggested that acid rain can have an indirect impact on wildlife by allowing metals bound to soils and sediments to be released into aquatic environments, where animals, like birds, that eat in these environments may consume harmful compounds.

Effects On Humans

• Numerous harmful impacts of acid rain on human health.

• The most noticeable symptoms are offensive smells, reduced sight, and irritation of the skin, eyes, and respiratory system.

• Some of the direct effects include cancer, emphysema of the lungs, and chronic bronchitis.

• The detrimental effects on human health are a result of elevated concentrations of dangerous heavy metals as manganese, copper, cadmium, and aluminum.

• Higher altitude acid rain produces a thick acidic fog that hangs low in the sky and reduces visibility.

• In addition to its negative effects on air quality, acid rain also significantly affects the ecosystem balance.

• Acidic rain causes lost harvests because it can injure trees and crops when it rains directly on them.

• The availability of fish is unbalanced, which hurts the fishing business.

Damages Buildings

• Buildings and structures are harmed by acid rain because it corrodes exposed metal and dissolves stone.

• Before people were aware of the problems caused by acid rain, metals, limestone, and marble were extensively used as building materials exposed to rain and fog.

• Calcium carbonate or calcium-based compounds present in some of these goods can be dissolved by acid rain.

• Although sandstone is more resistant to acid rain, it can eventually develop black surface deposits.

Acid Rain: Global Scenario

• Most of Scandinavia, Canada, the North and Northeastern States, and Northern Europe (particularly West Germany and upland Britain) all exhibit these traits.

• A few of the hotspots for acid rain on either side of the Atlantic are the New York Adirondack Mountains, the Great Smoky Mountains, parts of Wisconsin and Minnesota, and the Colorado Rockies.

India's Acid Rain

• There have been several cases of acid rain in India in the past, but they were relatively sporadic.

• India has reported cases of acid rain, notably in the rural districts of Silent Valley and Bhubaneswar as well as the industrial neighborhoods of Chembur and Colaba in Mumbai, adjacent to the Singrauli Super Thermal Power Plant, and with an average pH value of 5.3.

• Along with more recent reports from Kalyan, Chembur, Sinhagad, and Delhi, acid rain has recently been reported in the National Capital Region of Panipat in Delhi.

• Pune's rainfall has been recognised to have an alkaline pH, however its value has been declining.

• An increase in sulphate and nitrate ions and a reduction in calcium ions are the main contributors.

• The pH of the rain in the areas of Agra and Delhi has likewise fallen over time.

• The IITM has been researching acid rain for the last three decades.

• The pH is higher (pH>7.0) in the north and northwest of India.

• India's northeastern and southern regions have slightly lower pH values (6.0–7.0).

• The fact that acid rain may not materialize is the only positive news for India.

• This is because the nation's soils, which are typically alkaline-rich, and its tropical climate neutralize the toxins.

Actions To Prevent Acid Rain

Lowering the levels of sulphur dioxide and nitrous oxides

• Numerous strategies have been developed by scientists to lessen the amount of sulphur dioxide produced by coal-fired power plants.

• Utilizing coal with less sulphur is one alternative. Another method to get rid of some sulphur from coal is to "wash" it.

• At the power plant, scrubbers can be added to remove sulphur dioxide from gases leaving the smokestack.

• Some power stations are changing their coal-burning procedures due to the production of nitrogen oxides during the combustion of coal and other fossil fuels.

Cleaner Vehicles

• The main polluting sources that cause acid rain are cars and trucks.

• When all of the vehicles on the road are combined, a single car does not release a lot of pollution, yet it does.

• The quantity of nitrogen oxides and other pollutants produced by new vehicles must therefore be restricted by automakers.

• One such piece of technology found in autos is the catalytic converter.

• For more than 20 years, this piece of machinery has been utilized to reduce the amount of nitrogen oxides produced by vehicles.

• In some new cars, cleaner fuels like natural gas are also an option.

• Automobiles with low emissions produce less pollutants and are better for the environment.

Desulphurization of Flue Gas

• A group of methods known as flue-gas desulfurization (FGD) are used to remove sulphur dioxide (SO2) from the exhaust flue gases of fossil-fuel power plants as well as from other sulphur oxide-producing processes like waste incineration.

• The majority of FGD systems have two phases: one to remove fly ash and another to remove SO 2.

• It has been tried to remove fly ash and SO2 together in a single scrubbing vessel.

• As a result, these technologies significantly reduce SO2 emissions.

Conclusion

The 1970s saw the destruction of numerous regions in North America and Western Europe due to acid rain. Since then, steps done in various directions to combat the problem have steadily contributed to some degree of containment. According to recent studies, developing countries like China and India are just as seriously at risk from acid rain as certain historically developed countries were. Even the latter needs a lot of time to recover entirely from the earlier instances of severely corrosive rain.