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Atmospheric pollutants in the lower atmosphere essay.

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Introduction

Atmospheric pollutants in the lower atmosphere The atmosphere becomes polluted by both natural processes and the activities of humans. Volcanoes can release toxic gases including sulfur dioxide. Lightning produces toxic nitrogen oxides and ozone. Let us examine some gases that pollute the lower atmosphere. Lower atmospheric pollutants often include particulates such as soot from forest fires and the exhaust from industry. Metal dusts and concrete dusts also are atmospheric pollutants, as are vapours from solvents used in industry and domestically. Carbon dioxide The concentration of carbon dioxide has shown a gradual increase during the twentieth century. The burning of fossil fuels such as coal and oil products has caused this gradual increase in carbon dioxide levels. This increase in carbon dioxide is one of the factors that scientists believe has added to global warming. This is sometimes referred to as the 'enhanced greenhouse effect'. Carbon dioxide absorbs infrared (IR) ...read more.

Middle

Its natural concentration in the troposphere is about 0.1 ppm, but this may rise 500 times in locations where there is a high density of automobile traffic. Nitrogen oxides (NOx) Emissions from road traffic are the principal sources of nitrogen oxides such as NO and NO2. In the combustion chamber, nitrogen and oxygen combine in the presence of a spark to form nitric oxide (NO). This gas in turn reacts with oxygen to form NO2. The conversion to nitrogen dioxide is catalysed by carbon compounds and sunlight. NO can also react with any tropospheric ozone (O3) to produce NO2. N2(g) + O2(g) 2NO(g) 2NO(g) + O2(g) 2NO2(g) NO(g) + O3(g) NO2(g) + O2(g) Atmospheric studies show that the concentration of nitrogen oxides in the air in cities is greatest when traffic volume peaks. ...read more.

Conclusion

Nitrogen dioxide is also oxidised to form nitric acid, which contributes to acid rain. Ozone Ozone is a pollutant in the lower atmosphere. Tropospheric ozone represents about 10% of all the atmospheric ozone. It is generated as shown by the equation in the previous section (Nitrogen oxides). The higher UV levels in summer lead to greater photochemical smog problems at this time. The natural background level of ozone in the troposphere is about 0.02 ppm whereas in photochemical smog the level may rise to 0.3 ppm or higher. Measurements of ozone levels in Australian capital cities over the last 30 years show that following an initial decline in the 1980s, the levels have remained fairly steady (~0.13 ppm average maximum hourly levels in Sydney) rather than declining. Ozone is very poisonous at levels above 20 ppm. It readily oxidizes organic tissue and thus disrupts normal biochemical reactions in the body. It irritates the eyes and causes breathing difficulties. ...read more.

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Response to the question

#1# The response is well laid out with excellent care taken to lay the essay out in a logical manner with care taken to explain the effects of each gas thoroughly. Starting out with a logical plan of where you ...

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Response to the question

#1# The response is well laid out with excellent care taken to lay the essay out in a logical manner with care taken to explain the effects of each gas thoroughly. Starting out with a logical plan of where you are going with your essay will save you time in the long run and may stop you from making sill mistakes in the future. The response covers all of the main gases that can be attributed to global warming.

Level of analysis

#2# The level of detail put into each of the gases is superb with the amount of research put in really showing through. The essay could had been made better with a conclusive paragraph summing all of the points up, as it makes a neater end to the essay. Putting detail into your points to back them up gives them more credit and also shows to the examiner that you cared enough about the work to spend the time researching the topic.

Quality of writing

#3# The writing is of a very high level with some terms being used being only found in A-level. The fact that some words have been put in bold draws the examiners attention to them quickly, this means that marking points are easily found instead of the examiner having to go searching from them. The spelling and grammar are fine.


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