Atmospheric Changes and Energy Loss Due to Industrial and Residential Combustion of Hydrocarbon Fuels
Susan M. Burke
Your feedback is important to us!
After viewing our curriculum units, please take a few minutes to help us understand how the units, which were created by public school teachers, may be useful to others.
Give FeedbackLesson 3
Air Pollution Chemistry
Nitrogen—The atmospheric chemistry of nitrogen oxides is more complex than that of sulfur and because of the 40% increase in NOx emissions from Ohio, Illinois and Indiana, nitrogen compounds are of paramount concern. Nitrogen reactions include the following: (1) Nitrogen reacts with oxygen to form nitrogen oxide which rapidly oxidizes further to produce nitrogen dioxide: (2) Ozone is produced in the presence of nitrogen oxides when photochemical reactions and hydrocarbon reactions take place: (3) Nitrogen oxides react with H20 to form nitric acid, a great contributor to acid precipitation, and: (4) Nitrogen oxides result in the production of PAN (pereoxyacetyl nitrate) which has a deleterious effect in laboratory testing of vegetation. Both nitrogen oxide and nitrogen dioxide have a low ‘dry deposition’ velocity and stay airborne longer. They are less water soluble than sulfur oxides making cleansing by washout limited. Oxidation of NO2 to HNO3 involves the OH radical of atmospheric ozone. Nitric acid aerosols are removed from the atmosphere by dry deposition.
12
(figure available in print form)
Sulfur, the greatest mass quantitatively of air pollutants is attributed to sulfur dioxide emissions and particulate matter. Both in dry deposition and when reacting with H20 to form dilute sulfuric acid, sulfur has taken its environmental toll.
(figure available in print form)
Concurrent with the above process of dry deposition, rainout, and washout, a continuous homogenous oxidation of sulfur dioxide occurs in the presence of ultraviolet energy. The oxidation rapidly increases in the presence of nitrogen oxide and olefinic hydrocarbons which act as catalysts. Particulate sulfates have a greater atmospheric lifetime than does sulfur dioxide and sulfuric acid aerosol can stay in the air for 2-4 days and travel 1000 plus km with an atmospheric speed of 20 km per hour.
13
The particulate matter both solid and liquid aerosols, arise in the atmosphere from condensation or dispersion and drop by gravitational settling. The particulate matter varies in size and is measured in the atmosphere in mG/m
3
(milligrams per cubic meter) because being non-gaseous it is not possible to measure it by volume. The particulate matter has an effect on the environment by scattering or absorbing sunlight. Cities effected receive 15-20% less or sometimes 1/3 reduced solar radiation. Particulates reduce visibility by attenuating air molecules therefore reducing contrasts.
14
(Appendix 7)
(figure available in print form)
Carbon dioxide, a byproduct of hydrocarbon consumption and specifically dense in areas of great coal combustion, enters the atmosphere in relatively large quantities. The ambient C02 pressure remains fairly constant however due to plant utilization in photosynthesis and therefore poses no great threat. With increased CO2 atmospheric radiation balances are subject to change. Increased C02 which allows visible infrared (heat) rays to penetrate but prevents terrestrial radiation can cause the earth’s surface temperature to rise. This is known as the ‘greenhouse’ effect.
15
Appendix 8. A past value of 290 ppm of C02 has now increased to 337 ppm or 15% more. The earth’s surface temperature increases 1.9°C for every doubling in the ppm amount of atmospheric C02. When temperature inversions occur or there is movement of high pressure cold fronts, severe smog episodes result. These episodes pose extreme environmental problems and thousands of human fatalities.
16