Atmosphere pollutant agents: acid rain
The world evolves in an accelerated or disproportionate way if you want, in regard to industrial and technological development, all these advances have brought with them a series of consequences that every day become more noticeable on our planet.
Pollutants of the atmosphere
The waste generated by the action of man has broken the harmonic balance of the Earth, for example the emissions of gases from the burning of fossil fuels, the diversification of industrial processes and the growing demand for energy, are the main causes of agentspollutants in the atmosphere.
The increase in these pollutants has brought repercussions such as the weakening of the ozone layer, global warming, greenhouse effect and acid rain, as well as disorders associated with people’s health.
Acid rain
A rain as acid can be considered when the value of its pH is less than 5, this phenomenon originates when the water vapor concentrated in the atmosphere product of evaporation by solar radiation, reacts with sulfur oxides and nitrogen. These oxides enter the classification of acid oxides, are binary compounds constituted by oxygen and a non -metallic element, and have the ability to react with water causing acid. But how do these gaseous oxides arrive at our atmosphere?
Nitrogen oxides emissions
The presence of nitrogen oxides in the atmosphere is associated in more than 70% to emissions from automotive combustion either of gasoline such as diesel, burning of coal and natural gas in thermoelectric plants, also generate a considerable portionof emissions of these oxides but due to the regulations imposed internationally their incidence has decreased considerably, although perhaps it is not yet sufficient. The smoke from vehicles is the main responsible for the presence of nitrogen oxides in the atmosphere
When an un controlled combustion process occurs, the high temperatures generated provide sufficient energy to the nitrogen molecules present in the air, to end up breaking and producing the oxidation of nitrogen to nitric oxide and nitrous oxide, that is, they usuallyThey are incomplete combustions by -products, since free oxygen is completely burned in complete combustion and should not react with nitrogen. This is the reason why carburation engines produce many more nitrogen oxides emissions, than injection engines where more controlled combustions are carried and that produce greater energy efficiency.
Sulfur oxides emissions.
The emanations A of sulfur dioxide (SO2) and sulfur trioxide (SO3) at the anthropogenic level are usually associated with oil refining processes and natural coal burning processes. Oil refineries generate emissions with high concentrations of sulfur oxides.
Natural coal in its composition contains approximately 3 % by weight of sulfur and that is why it represents one of the main sources of these emissions, since it is widely used for the generation of electricity through its combustion, due toits abundance in nature and the low cost it represents.
Volcanic sulfur dioxide.
Another sources that contribute to the increase in these oxides in the atmosphere is volcanic activity, when eruptions are generated.
An example of this was the eruption of the Laki volcano in Iceland in the year of 1783, the toxic cloud of sulfur dioxide conducive acid rain in various regions of Europe and the world, affecting agriculture, which generated a period of hungry of three threeyears.
In 2014, a study conducted by the Canary Islands Volcanological Institute to the Fogo Volcano in Tenerife, through the use of optical sensors determined that after the eruptions of said volcano, emanations of up to 12 thousand tons of daily sulfur dioxide were recorded, an impressive figure without a doubt. Once the main sources of emission of these gaseous oxides are known, let’s see how acid rain forms.
Reactions involved in the formation of acid rain.
Both sulfur dioxide (SO2) and nitrous (no) oxide have less chemical stability than sulfur trioxide (SO3) and nitric oxide (NO2) in respectively, which is why in atmospheric conditions they end up reacting andbecoming these species of greater stability. In this way they add to those already directly from emissions as shown in the following image. Both oxides when coming into contact with water react according to the following equations:
- SO3 reaction. Sulfur trioxide promotes sulfuric acid formation.
- NO2 reaction. Nitric oxide encourages nitric acid formation.
The species formed from these oxides, have the ability to give protons, dissociating the H+ ion that is responsible for reducing the pH of the water that subsequently rushes to the earth in the form of rain.
Consequences and effects of acid rain.
It is responsible for the acidification of rivers, lakes and seas, which represents a serious problem for aquatic ecosystems, which are altered by the variations of pH in the water causing the death of fish and other ways of life. Macaba with vegetation causing trees, grasslands and various species of plants to wilt.
In addition to directly destroying vegetation, the acidification produced in the soils does not allow the development and growth of new species, which is why acid rain represents a big problem for agriculture worldwide. It contributes to the eutrophication phenomenon, since the nitrates and sulfates it provides, generate the nutrients for the accelerated proliferation of algae that consume the dissolved oxygen in the water.
Acid rain corrodes metal and concrete structures. Metals oxidize in an acidic medium due to their tendency to lose electrons, in the case of concrete or cement infrastructures they all present in their composition a high percentage of calcium carbonate Caco3 an alkaline salt that easily reacts with acids, whatimplying its wear.
It has generated hambruna periods in various regions of the planet, since by not allowing an optimal development of agriculture, nor the growth of animal food, it makes food production difficult.
At present, the areas that are most affected by acid rain are:
- East of the United States, specifically the regions surrounding the city of New York for intense industrial activity and contamination associated with vehicular traffic.
- Germany is also a victim of acid rain, but it is worth mentioning that this is one of the most industrialized countries in Europe and all this industrialization translates into more emissions to the atmosphere.
- Holland and Denmark have been other affected countries, but in these cases the problem has not been caused by their own emissions but by those from the United Kingdom.
Actions to take
All actions to reverse this phenomenon must be directed in attacking the causes that generate it, the main thing is to reduce the emissions of these polluting agents for this we must:
- Reduce the use of fossil fuel, among which are oil derivatives and natural coal.
- Use filters in vehicles that minimize the presence of pollutants in their emissions.
- Reduction in the circulation of carburation vehicles and foster the use of vehicles with injection system.
- Greater control and commitment by the authorities of the various countries in environmental matters.
- The gases of chimneys of the industries must be previously treated before being issued to the atmosphere, all this to ensure that they comply with the limits in the concentrations of pollutants allowed by environmental legislation.
- Promote the use of electric transport.
- In previous publications I talked about some methods for the elimination of these oxides responsible for acid rain.
- The problem of sulfur dioxide in combustion gase emissions and theoretical foundations for washing with calcium carbonate.
- Titanium dioxide as an alternative against air pollution.
All the efforts we make in this sense, however small that they seem in some way they will contribute to reverse all these damages that we have been promoting to our planet. We’re still on time!
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