Acid rain is a result of the atmospheric moisture reacting with nitrogen oxide and sulfur dioxide. The resulting product of the reaction between the two gases and the water in the air gives a liquid with a pH of 5.3. The pH of the resulting precipitations is determined by the level of the concentration of these two gases in the atmosphere (Chris 2). The term acid rains refer to all forms of precipitation such a fog, mist, hail and storms with a pH value of 5.3 or below. The regular shower has an acidity of between 5.3 and 6.0 due to the presence of carbon dioxide in the air. The Carbon dioxide gas dissolves in the moisture to a carbonic acid which is a weak acid. Only pure water has a pH of 7.0.
The acid rain is deposited in two on to the earth surface, either through dry deposition or wet deposition. A wet deposition refers to when the deposition occurs in the form of rain, sleet, snow or fog. On the other hand, dry deposition refers to the deposit of the pollutants as dry particles, e.g., dust.
There are two major causes of acid rain, physical and artificial causes. The physical causes are innate phenomenon leading to the release of nitrogen oxide and sulfur dioxide (Chris 3). The innate causes include volcanic eruptions, which is the primary cause. The dangerous gases from the magma below the earth surface at high pressure during volcanic eruptions. Volcanic activities are the most significant natural contributor to acid rain (McCormick 12). Besides the volcanic eruption, other natural causes include lightning, decomposing vegetation, and wildfires. The decomposing vegetation release dimethyl sulfide, the sulfide contains sulfur a significant cause of acid rain. Lightning strikes generate nitrogen oxide in the atmosphere (McCormick 12). However, the lightning is the least natural cause of acid rain.
Other than volcanic eruptions, human activities Human activities are the primary causes of acid rain. Vehicles, industries, and power plants significantly contribute to the high amount of Nitrogen and sulfur gases in the atmosphere. The combustion of coal to produce electricity is one of the primary causes of nitrogen oxide and carbon dioxide. These two gases react with the humid air to form an acidic rain. Coal is a hydrocarbon with a high concentration of carbons molecules but lower hydrogen molecules. The carbon-hydrogen ration stands at 0.8 thus the necessary addition of hydrogen during combustion to produce energy. The incomplete combustion coal results in nitrogen and sulfur oxide gases.
The acid rain adversely affects the life existence of the ecosystem. When it rains, the acidic water sinks into the soil lowering its pH depending on the acidity of the rain. Acidic do not support any agricultural activity as most crops cannot grow in an acidic environment. Most plants cannot grow in soil having a pH below 5.3 as it is too acidic (Ernst-Detlef, Lange and Oren 302).Additionally, acidic water has leaching effect in the ground thus draining away nutrients living the land infertile. Besides, most living organisms cannot live in an acidic environment and most like likely die affecting the soil aeration. The addition lime can only neutralize the acidic soil. Lime is a calcium carbonate thus reacting with the acid to form carbon dioxide.
The aquatic life is also not spared by the damaging effects of water acidity. Most of the acid precipitation ends up in large water bodies like oceans and lakes. Most of aquatic animals and plants cannot survive in an acidic environment below the pH 4.8. The increased accumulations of acidic water in the oceans result in the change in the general ecosystem as the animals have to adapt or to the new environment or face extinction. Alternatively, they can migrate to a new environment that favors their existence. The inability for eggs to hatch at the pH below 5 meaning the most of the egg laying species can quickly become extinct.
The solution to acid rain is minimizing the emission of nitrogen oxide and nitrogen dioxide to the atmosphere. As noted earlier these two pollutants are the primary cause of acid rain thus controlling their discharge lowers the possibility of having acid rains.
Several regulations are in place to limit the amount of these pollutants released to air. There is increasing awareness campaigns to motivate people use green sources of energy such as solar and geothermal. These sources have minimal effect on the environment as they do not emit these hazardous gases to the atmosphere. Solar energy is one of the safest and affordable sources of energy. The use of these alternative energy sources is an excellent step in fighting the acid rain as they reduce the emission of the pollutant gases into the atmosphere.
Another way of reducing the acid rain is investing in electric trains, cars, and planes. Cars are one of the major contributors to the air pollution. The emissions from the automobiles are majorly carbon dioxide and smoke with few traces of nitrogen oxide and sulfur dioxide. The small trails if combined with the millions of cars on the road then it translate to a significant amount. Additionally, the carbon dioxide emitted by vehicles also reacts with the atmospheric vapor to form acid. Even though the acid rain due to carbon dioxide does not have a high PH, a high concentration of carbon dioxide can result in a relatively an acidic rain.
The invention of the electric train is one the most significant breakthrough in control the air pollution associated with transport. The diesel engines in trains have a substantial contribution of the atmospheric nitrogen oxide and sulfur dioxide. Moreover, most of the passengers especially cargo trains, are still powered by coal.
Coal is one of the leading sources of carbon dioxide to the atmosphere and the major causes of greenhouses effect. In 20011, coal plants in the United States only emitted 1.7 million tons of carbon dioxide (EIA). Besides the carbon dioxide, coal plants also produce a significant amount of sulfur dioxide and nitrogen oxide that are the primary causes of acid rain. Reducing the reliance on coal as a source of energy is critical in control air pollution. In fact, there is an ongoing campaign by the United Nations Environment Program (UNEP) to stop the usage of coal as a source of power.
Apart from using alternative sources of fuel, there should be legislation that controls the use of coal. For instance, the United States Clean Air and Water Acts demand the factories minimize the amount pollutants released to the atmosphere and water respectively. Such legislations limit the reckless use of products such as coal that emits nitrogen oxide and dioxide to the atmosphere. The UN should develop a guideline for accepted limit for the two pollutants from each country. Some nations do not have any existing legislation to control the menace.
The use of coal and petroleum is still very prevalent developing countries, this due to lack of enough funds to invest in environmentally friendly products like the electric trains and LPG gas. World Bank and other developed nations can have a partner with such countries in areas like infrastructural development. For instance, they can help the developing countries construct modern railway transport system that uses electric trains instead of the diesel engines.
The removal of sulfur (II) oxide from waste gas also contributes to the reduction of acid rain. This process is called Flue Gas Desulphurization (FGD). This process involves fitting exhaust chimney with a wet scrubber. The scrubber is responsible for the extraction of the sulfur gas from the fumes (Sun, Cheng and Baig 67). Besides the scrubber, a slurry calcium carbonate is injected into the chimney. The sulfur dioxide gas present in the fumes dissolve in the wet surface forming sulfuric acid, the acid then reacts with the calcium carbonate (lime) to give a less harmful carbon dioxide. Apart from the carbon dioxide, the reaction also produces calcium sulfate that is deposited on the linings of the chimney. The sulfate deposits are removed physically from the surface of the exhaust pipes.
Another solution to acid rain is an investment in the mass transport system. As noted earlier, motor vehicles are one of the leading contributors to air pollution. Having a well-developed mass transport system limits the number of cars on the roads at a particular time. Fewer vehicles on the streets mean there is reduced pollution emission sources are reduced. Furthermore, the mass transport system can be electric trains or buses. Additionally, solar buses can be used in tropical areas with sufficient sunshine. These two options have zero emission to the environment thus lowering the accumulation of the pollutants that result in acid rains.
The installations of scrubbers on the linings of the industrial exhaust chimney have played a significant role controlling the nitrogen and sulfur oxides emission to the air. Besides the volcanic eruptions, industrial emissions are the primary causes of the acid rain. The scrubbers extract any traces of sulfur and nitrogen oxides by reacting with two gases to form a sulfuric acid and nitric acid respectively. The acids are then passed through a lime solution creating a carbonate that is physically removed from the chimneys’ lining.
In conclusion, acid rain is a result of nitrogen oxide and sulfur dioxide reacting with the vapor. These two gases react with atmospheric moisture to form an acid water that the precipitates to the ground. The sources of these two gases can either be natural or human-made. Whereas there is very little control on the physical causes, human-made sources can be regulated.
Chris, Park C. Acid Rain (Routledge Revivals): Rhetoric and Reality. Routledge, 2013.
EIA. January 2012. 11 November 2017.
Ernst-Detlef, Schulze, Otto L. Lange and Ram Oren. Forest decline and air pollution: a study of spruce (Picea abies) on acid soils. Vol. 77. Springer Science & Business Media, 2012.
McCormick, John. Acid Earth: the global threat of acid pollution (Vol. 4). Routledge, 2013.
Sun, Mingyang, Jiaai Hou, et al. “The relationship between speciation and release ability of mercury in flue gas desulfurization (FGD) gypsum.” Fuel 125 (2014): 66-72.