CHEMISTRY IN THE TROPOSPHERE // Photochemical smog

in StemSocial3 years ago

Author: @madridbg, through Power Point 2010, using public domain images.

Welcome to all those readers of the #Hive community who are passionate about scientific content associated with the world of chemistry. In this issue, it is the first of a series of knowledge associated with the phenomena that occur at the level of one of the layers of our planet (the troposphere), focusing on the chemical aspects behind photochemical smog, a phenomenon that affects the levels and quality of oxygen on earth.

INTRODUCTION


The chemistry behind the systems of layers that make up the planet is quite complex, in it we can find chemical processes catalyzed by solar radiation and others are associated with the activity of man on earth and natural phenomena.

Although it is true, the planet's atmosphere is made up of different layers that do not allow us to understand how it works (troposphere, stratosphere, mesosphere, thermosphere). In this particular, we will not focus on studying what is related to the layer where the greatest amount of human activities and all the earth's meteorological processes take place.

Therefore, our starting point is the troposphere, a region located about 12 kilometers above the Earth's surface, where the greatest amount of activities that affect planetary health (greenhouse effect, acid rain, photochemical smog, among others) take place and which have a direct incidence on the evolutionary activities of humans.

In this sense, through this publication we will make a tour of the environmental problems that are developed at the troposphere level, focusing on the photochemical smog and the chemical basis behind this phenomenon

Fig. 2. Layers of the Atmosphere. Author: @madridbg, through Power Point 2010, using public domain images.


ENVIRONMENTAL ISSUES AT THE TROPOSPHERE LEVEL


In this section of the topic, we will focus on describing some of the environmental problems that affect our planet as a result of human action, so it is not surprising that the layer closest to the earth (troposphere) is the one that is most easily modified or disturbed. In this sense, we will make a description of some of the environmental problems affecting the earth today. We will break them down below:

THE PHENOMENON OF ACID RAIN

This phenomenon is related to the production of sulfur dioxides (SO2) product of the combustion process that takes place in thermoelectric power plants. Sulfur dioxide in the presence of oxygen in the air, produces sulfur trioxide (SO3), a compound that when it comes into contact with rainwater produces sulfuric acid (H2SO4), one of the main responsible for the decrease in the pH of rainwater. This has caused aesthetic damage in the construction of cities and biological damage that threatens the life of fish, as well as forest species on the planet.

Fig. 3. Representation of sulfuric acid synthesis. Author: @madridbg, through Power Point 2010, using public domain images.

Fig. 4. Damage caused by acid rain. Edited by @madridbg. Author: Chris LeBoutillier

AIR POLLUTION

The industrialization of the cities, represents the main problem that attempts against the quality of the air that we breathe. The burning of fossil fuels, coupled with the large amount of waste (carbon monoxide and dioxide) generated by the millions of cars that travel through the big cities have altered the composition of the nitrogen-oxygen mixture in the air.

The problem is intensified when nitrogen monoxide (NO), generated in industrial processes and in automobiles, interacts with the air generating nitrogen dioxide (NO2) that when coming into contact with rainwater ends up generating nitric acid, further lowering the pH of the water and deepening the acid rain phenomenon.

Fig. 5. Industries are a continuous source of contamination in the areas where they operate. Edited by @madridbg. Author: Chris_LeBoutillier

GLOBAL WARMING

At a thermodynamic level, global warming is due to the breakdown of the thermal balance of the planet, as a result of the industrial activities of mankind. This balance was formed between the atmosphere and solar radiation, which reached our planet and emerged in the form of infrared energy.

At present, the balance is compromised due to the rupture of the ozone cup since much of the radiation does not return to space, but is concentrated in the troposphere as a result of greenhouse gases, causing an increase in the temperature of the earth. This effect can be seen with more significance at the level of the polar caps whose deterioration is alarming, due to the amount of ice that melts, which in turn generates meteorological variations that produce havoc in some cities.

Another alarming situation is what originates from photochemical smog, which we will study in depth in the following section.

Fig. 6. Global warming has been responsible for the loss of bio-diversity. Edited by @madridbg. Author: enriquelopezgarre


THE PHENOMENON OF PHOTOCHEMICAL SMOG


Chemically, smog is produced as a result of combustion, in many cases incomplete and carried out at high temperatures, for example in car engines and oil plants and refineries, where large amounts of waste are released into the air of the planet.

In this sense, smog is a combination of acid rain, air pollution and global warming, since the reactions generated in these phenomena are catalyzed by the action of light, causing a photochemical process, hence the term smog which means cloud of pollution.

Although it is true, there are many substances that are considered pollutants, according to research we will mention carbon dioxide (CO2), carbon monoxide (CO), nitrogen monoxide (NO), which are considered as primary pollutants, since they participate in a series of chemical reactions that produce intermediate substances that threaten the health of the planet.

Therefore we will instruct the reader on the transformations that one of the above-mentioned substances undergoes. In this sense, nitric oxide (NO) released into the air by the action of automobile combustion, is rapidly transformed into nitrogen dioxide (NO2), a substance that in the presence of sunlight catalyzes and decomposes, forming monoatomic oxygen (O) and again nitrogen monoxide. According to the following reaction.

Fig. 7. Representation of the synthesis of nitrogen monoxide by the action of ultraviolet light. Author: @madridbg, through Power Point 2010, using public domain images.

Up to this point the reaction seems harmless, the difficulty begins when the monoatomic oxygen starts its harmful path generating ozone (O3) that at tropospheric level is highly harmful.

Fig. 8. Representation of ozone formation at the tropospheric level. Author: @madridbg, through Power Point 2010, using public domain images.

The planetary ozone fulfills a double function and behaves like a bipolar person, to describe it in some way, at the atmospheric level is an excellent ally that protects life on the planet. It is in charge of filtering solar radiation so that it does not impact the earth's surface with much energy.

Fig. 9. Function of the ozone layer. Edited by @madridbg. Author: one94

On the other hand, at a tropospheric level it is highly destructive since, being very reactive, it can react with many substances of our daily life. For example, it reacts with the hydrocarbons in the rubber of cars causing cracks on them. It also affects lung tissues and other biological molecules.

Another problem caused by the presence of ozone, is the excessive synthesis of (NPA) peroxyacetyl nitrate, which occurs when it interacts with aldehydes or ketones. This substance is a lacrimator par excellence.

In general, this phenomenon attacks the crops, produces respiratory problems, poor visibility of the areas where it occurs, lung cancer as it deteriorates the membranes, also produces the formation of free radicals that rise into the atmosphere attacking the ozone in that area, which contributes to the degradation of the barrier that protects us from sunlight.

Fig. 10. Urban area in the presence of photochemical smog. Author: Martin Vorel


CONTRIBUTIONS OF THE THEME


Through research, we can delimit the different problems that afflict the planet as a consequence of the human being's rentier action, which leave aside the environmental welfare and focus on activities that improve the economy and social welfare. Similarly, we can glimpse the different mechanisms of chemical reactions that are present in some of the environmental problems studied.

BIBLIOGRAPHY CONSULTED


[1] Chang, R. (2010). Química. Decima edicion. McGraw-hill Interamericana editores. ISBN: 978-607-15-0307-7.

[2] Garcés, L and Hernández M. (2004). Acid rain: a physicochemical phenomenon of local occurrence. Lasallian Research Journal, vol. 1. No. 2. Lasallian University Corporation. Antioquia, Colombia.. Article: Online Access

[3] Granados D; López, G and Hernández M. (2010). Acid rain and forest ecosystems. Chapingo Magazine. Series Ciencias Forestales y del Ambiente 16(2): 187-206. Article: Online Access

[4] Mathews, C. K.; Van Holde, K. E.; Ahern, K. G. (2002) . Bioquímica. PEARSON EDUCACIÓN, S. A., Madrid, ISBN: 978-84-832-2694-0. Materia: Bioquímica, 577. ÁREA: CIENCIAS

[5] McMURRY E., John y Fay C., Robert. (2008). Química general. Quinta edición PEARSON EDUCACIÓN, México, 2009 ISBN: 978-970-26 1286-5.

[6] Ralph, H. Petrucci, William S. Harwood, E. Geoffrey Herring. (2003). QUIMICA GENERAL. Octava edición. PEARSON EDUCACIÓN. S.A., Madrid.

[7] Vargas Francisco. (1996). Prevention And Control Of Chemical Products Risk. Rev Esp Public Health. 70: 409-420. N. 4. Article: Online Access

[8] WADE,LEROY. (2011). . ORGANIC CHEMISTRY. VOLUME 2. SEVENTH EDITION. PEARSON EDUCATION, MEXICO, 2011 ISBN: 978-607-32.()793-5.


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