Acid Rain

Uros Osmokrovic

Science 9A

Mr. Youell

20.03.2015

Acid rains

Acid rain is rain that has lower pH value than normal rain that falls in unpolluted parts of territory. Acid rain is mixture of CO2, NOx and SO2 and water. Carbon dioxide, sulfur dioxide and nitrous oxide combined with clouds in our atmosphere form Acid rains, Acid snow and even acid fog (Figure 1).  pH value of Carbonic acid is 3.8 , sulfuric is 1 and nitric acid is 1. We can conclude that Carbonic acid is not that much acidic as sulfuric and nitric acid. Carbonic acid is mixture of CO2 and water. CO2 is broadcast from large factories, cars and even we create CO2, but not in big concentrations like factories. NOx and SO2 is broadcast from factories too. All of compounds for acid rains are emitted by human creations. We need to adjust those concentrations so nature can adapt. Nature is made to adapt to various changes, but we emitted a lot of CO2, NOx and SO2 in small period of time so if we continue like this we will have great problems. It doesn't mean that only human’s produce gas that forms acid rains, acid rain can be produced by nature too. Nature can fight against acid rains. Limestone is nature’s weapon to defend against acid rains. In reaction between acid and limestone you get neutral solution, but from time to time a lot of acid rains will wash away the limestone.

Figure 1 (SO2 and NOx forms H2SO4 and HNO3 which are strong acids)

So why acid rains are so important and what impact do they have on our world? Firstly we already know that a lot of organic material dissolve in acid. With that information we have we can conclude that  everything will dissolve in acid rain too. Acid rain has low pH values so it makes streams rivers and sea acidic. Water surfaces can neutralize themselves with surrounding soil, like I mentioned limestone. If there is not enough soil that can neutralize acid in water surfaces then water becomes acidic. In areas where buffering level is low, acid rains releases aluminum which is highly toxic for aquatic organisms. That is why many aquatic organisms can’t adapt and eventually they die. All sorts of fishes and frogs can’t reproduce in acidic water. One of the most acidic lake is Little Echo pond in Franklin, New York. Acid rain doesn't only affect aquatic surfaces, it affects forests and soil too. Acid rain dissolves leaves of trees, it pollutes soil, it makes trees vulnerable on a lot of diseases. It deposits nitrates in forests and it is leading to increase nitrogen. Nitrogen is essential gas for plants. Nitrate is salt of nitric acid.  Nitrates can remove calcium and magnesium from the soil. When there is no calcium in the soil plants absorb aluminum nitrate (Which reacted with nitrate acid) for the soil, and they die from it. From this you can see that acid rains destroy all substances form soil so plants and trees can’t live anymore. Some forests are extinguished because of acid rain.(Figure 2)

Figure 2 ( Trees in the middle of the forest don’t have leaves because of acid rain)

 Acid rains don’t have great impact on human health, but it destroys building statues. Quantity of acid rains is increasing from year to year. Biggest quantity of acid rains are emitted in China.  (Figure 3)

(Figure 3 quantity of acid rains in million metric tons per year)

We can see that quantity of acid rain is increasing, so what can we do about it? The first step in solving a problem is to see what problem is. Problems are high concentrations of NOx, SO2 and CO2. How can we reduce concentration of those gasses in air? Firstly we can travel by public transportation, which will reduce nitrogen oxide in air. We can use coal that has less sulfur in it, so we can reduce sulfur in atmosphere too.  We can use scrubbers; those are devices that chemically remove SO2 from gas that leaves smokestack. Similar to scrubbers are catalytic converters that reduces NOx from gas that leaves the car.  Instead we can ride bicycles or even walk to near destinations. Cars and factories are not the only problem. Beside that we need to start saving energy. We should turn off computer, video games, machines when we don’t use them. We should use air conditioning in small amounts.  People should start buying equipment that uses less electricity. To lower pH value in lakes we should put a lot of limestone in them so it can neutralize with acids that are in water.  We need to spread the word about acid rains so everybody can be informed. We need to do this together, we can’t do this alone!