What causes Acid Rain?

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Rain water has some level of acidity but when hydrogen ion concentration(H⁺)is more the pH has a lower number. If the pH is less than 7 it is considered acidic, 7 being neutral. Normally the pH of rainwater is estimated to be around 5.6 but when the pH is lower than this value the rain is called Acid Rain. Acid rain is caused due to the many activities that take place on earth. Sometimes it is manmade and at other times natural such as when there is a volcano. Volcanos spew out ash which is high in sulfur compounds though majority of it is water vapor and a small percentage of other gases. When these sulfur compounds along with a bunch of other gases such as carbondioxide mix with rain, dissolve in water, due to their water solubility, and make the rain water acidic in nature.  As far as man made contribution to Acid rain is due to coal-burning power plants, factories that don't treat the gases that escape out, traffic congestion. All these result in acid precipitation, or fall back directly as acidic particles and gases. Acid Rain in general is a result of higher concentrations of both wet and dry mixture of sulfuric acid and nitric acid in the atmosphere.  The damaging effects of  acid rain can be seen in the waterways such as the lakes, marshlands and streams and destruction of the trees on higher elevations. The direct effect of acid rain is not felt by us most of the time but the fine particles of sulfur and nitrates can enter indoors and cause lung disorders such as asthma or bronchitis.

What are the natural sources of acid rain?

• Bacterial Decompositions: When animals and other living organisms die these bodies are attacked by different kinds of bacteria which help in the rotting of the body which is a part of the decomposition process. This decomposition though is useful to us as nature helps in recycling the dead this way, it also leads to the side effects of discharge of hazardous gases, which contributes to  acid rain.
• Natural Fires: Fires that happen naturally in forests and over oil-wells obliterate important resources.These natural fires also result in the generation of acids in the atmosphere which later come down as acid rain. The gases formed in these fires are hazardous though the fire may be natural, the gases produced are not different from the artificially produced fossil fuels.
• Volcanic Eruptions: Volcanic eruptions spew out gases which contribute to acid formation. The lava that comes out of a volcano is a mix of melted minerals. These minerals are at extremely high  temperatures under the surface of the earth. They always shift in a semi-solid state and when this semi-solid composition of minerals finds an escape in the earth’s crust, it escapes through the vents in the volcano and along with the mixture of minerals come out various other acid forming gases. The major gas released is water vapor but other gases such as sulfur-di-oxide, hydrogen sulfide, carbon monoxide, hydrochloric acid are also released in to the atmosphere which get leached out of the atmosphere when there is rain thus contributing to the acid rain.

What are the man-made sources of acid rain?

• Fossil Fuels: The production of nitrogen oxide in the environment is also contributed by the burning of fossil fuels. These fuels can be blazed by different plants in massive amounts or in lesser amounts by people. However, the whole effect is terrible than the atmosphere can tolerate. As the population grows up, not only the number of automobiles has increased, but also the number of houses with kitchens. Consequently, the emission of gases has considerably augmented.
• Automobiles: Over the past decade and also at present, usage of automobiles has been on a steady augment. These automobiles produce about half of the world’s total emission of nitrogen oxide. As the number of vehicles increases, the emission of nitrogen oxide also is increased. Consecutively, this nitrogen oxide reacts with the water droplets in the atmosphere and causes the formation of acid. These droplets hit earth in the form of acid rains.
• Production Plants: Production plants, with the use of coal as their key fuel, throughout the world produce 100 million tons of sulfur dioxide, which is approximately equal to 70% of that obtainable in the earth. This sulfur dioxide goes up and then remains hovering in the air, till it reacts with water to form acid. During condensation, these acid droplets form acid rains and cause destruction on the atmosphere.

What are the chemical sources of acid rain?

• Sulfur dioxides : Sulfur dioxides are discharged by burning coal, paper production, and melting metals. Sulfur dioxide can damage plant life, damage metals, and also creates lung problems.
• Nitrogen oxides : Nitrogen Oxides are discharged into the atmosphere through burning fuels like gasoline and coal. When nitrogen oxides react with volatile organic compounds, they create breathing troubles in people with asthma.
• Chlorofluorocarbons (CFCs) : CFCs are the chemicals that are used in industries such as  refrigeration, air conditioning systems, and consumer products.
• Carbon dioxide: Carbon dioxide is released by burning coal, oil, and natural gas.
• Volatile organic compounds (VOCs): VOCs are discharged into the environment by burning gasoline, wood, coal, or natural gas, solvents, paints, glues, etc.

What are the effects of acid rain?

Acid rain causes acidification of lakes and streams and causes damage to trees at elevations such as red spruce trees above 2,000 feet and many forest top soils. Acid rain also disintegrates buildings, statues, and sculptures that are major elements of any country’s artistic tradition. Sulfur oxide and nitrogen oxide gases and their particulate matter derivatives which are  sulfates and nitrates affect public health. 

How can the public contribute to reduce these issues?

By using alternative energy sources, public can help reduce these harmful effects. There are other sources of electricity other than fossil fuels which are nuclear power, hydropower, wind energy, geothermal energy, and solar energy. In all these, nuclear and hydropower are extensively used. Wind, solar, and geothermal energy have not yet been tried together on a significant amount. Also, there are alternative energies available to power automobiles, counting natural gas powered vehicles, battery-powered cars, fuel cells, and combinations of alternative and gasoline powered automobiles but these technologies have to be developed further more to be useful as these are currently still in the experimental phase and quite expensive for the average man to use them .

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