Acid Rain

Ivan Cukanić

Mr. Patrick Youell

March 19th 2015

Science 9E

Acid Rain

     Acid rain can be described as any form of precipitation with high levels of nitric and sulfuric acid. Because of its highly acidic nature, it can even dissolve stone. Rain (or any other form of precipitation) is a part of the water cycle, which means that water from bodies of water on land evaporates, and then comes back down to earth by precipitating (rain, snow, hail...). This cycle has been constant for millions of years. However, the water, in most cases, is not clean.

     Vapor mixes and bonds with carbon dioxide (CO2) in the air and bonds with it, making (H2CO3), which has can be as as acidic as pH 5.7. As thefreedictionary.com defines, pH is  "the symbol for the logarithm of the reciprocal of hydrogen ion concentration in gram atoms per liter, used to express acidity or alkalinity of a solution on a scale of 0 to 14, where less than 7 represents acidity, 7 neutrality, and more than 7 alkalinity"  After the reaction where H2CO3 is formed, it combines with water (H2O), it creates two acids. The resulting acids are HCO3 (Bicarbonate, aka hydrogen carbonate) and H3O (Hydronium ion). Eo Earth informs us that this is a normal, natural reaction, but sometimes in nature, when in surplus, rotting vegetation and erupting volcanoes are the cause for acid rain, for they emit nitrogen oxides (NOx) and sulfur dioxide (SO2). NO and SO2, which mix in the air to make nitric (HNO3) and sulfuric acid (H2SO4). These acids have a Ph between 3 and 1, depending on how many millimoles are measured. In human society, these gases (NOx and SO2) are emitted by mostly by factories and vehicles. These two gases react with vapor in the air and create acids, the same ones rotting vegetation and erupting volcanoes make, but this time in much larger quantities. Humans are the cause of the emission of these gases, as shown in figure 1, where the effects are also described. The emission of NOx and SO2 has increased 35% in 15 years, from 1990 to 2005. If we continue at this rate, in a century or more, most bodies of water will turn acidic.

(Figure 1: A diagram of the water cycle with a factory producing gas that mixes with the water added)

     Acid rain has many negative effects. The effects are ecological and cultural. Acid rain makes bodies of water acidic because of the water cycle, as EPA.gov states. This makes the body of water absorb aluminum from the soil, which makes the body of water toxic to aquatic life. The food chain affects almost all life, so if aquatic life is affected, then other land animals and birds will get intoxicated too, and could eventually lead to extinction. With the above mentioned increase in acids in precipitation, more and more bodies of water are getting acidic. There has been a very large increase of acidic bodies of water in the last 50 years. In time, large bodies of water such as oceans will get acidic if humans do not do anything about this issue, marine life could get intoxicated and cause a major extinction. Also, acid rain destroys forests, as seen in figure 2. It turns the water acidic, which may be toxic for certain plants. However, all plants are affected by the aluminum that is being dragged out of the soil by the acid and the acid "robs the soil of essential nutrients", as National Geographic would put it. This would mean that an entire forest, in the most extreme case, can be destroyed with acid rain. In society, acid rain can be very harmful. Acid rain is known to easily dissolve limestone and marble, and other types of stone containing large amounts of calcium carbonate. It is also known to increase the corrosion rate in metals such as iron, steel, copper and bronze. That is partially the reason why statues, gravestones, building facades and historic monuments are getting damaged. Writing in walls or surfaces made of some metals, limestone or marble can be damaged so much it becomes completely illegible. This makes job of archeologists very hard because certain evidence is gone. For this reason, in some countries, a protective shield of some sort is placed over the building/statue.

(Figure 2: A forest destroyed by acid rain)
     With the rates of acid rain getting higher, it is endangering life on Earth. Factories and vehicles using fossil fuel are producing millions of tons of NOx and SO2, which further combine with water to make acid rain. If factories used renewable energy sources, such as solar energy or wind power. Vehicles could all be electric and this would make acid rain much less common. Figure 3 demonstrates the effects of factories on acid rain and ultimately humans. However, for economic and political reasons this will not happen in the near future. Oil, coal and gas are a very big business controlled by politically powerful people, who can control the decisions of other important company owners and politicians, but it is left to the people to buy electric cars instead of regular cars that run on fossil fuels. If all the cars and other smaller transportation vehicles were electric, it would greatly contribute to decreasing the amount of acid rain that falls.
(Figure 3: A creative illustration of the harm of acid rain on humans caused by factories)








Bibliography:

http://environment.nationalgeographic.com/environment/global-warming/acid-rain-overview/


http://www.epa.gov/acidrain/effects/surface_water.html


http://www.eoearth.org/view/article/149814/





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