3. Air Pollution has been around a long time. Roman philosopher, Seneca, wrote of the heavy air of Rome in 61 AD. Edward I of England banned the burning of sea coal in craftsman’s furnaces be prohibited because of foul smelling fumes, 1306. Elizabeth I of England banned the burning of coal while Parliament was in session.
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20. Gaseous Air Pollutants Significance as Air Pollutant Properties of Importance Formula Name Some are emitted from automobiles and industries others are formed in the atmosphere. Many C x H y or HC Hydrocarbons Damage to vegetation and property. Produced mainly during the formation of photochemical smog. Highly reactive O 3 Ozone Formed during complete combustion. Possible effects in producing changes in global climate. Colourless and odorless CO 2 Carbon Dioxide Product of incomplete combustion. Poisonous. Colourless and odorless CO Carbon Monoxide Major component in the formation of photochemical smog. Brown to orange gas NO 2 Nitrogen Dioxide Produced during high temperature high pressure combustion. Oxidizes to NO 2 . Colourless gas NO Nitric Oxide Relatively inert. Not produced in combustion Colourless gas N 2 O Nitrous Oxide Highly poisonous Rotten egg odor H 2 S Hydrogen Sulfide Highly corrosive Soluble in water to form sulfuric acid SO 3 Sulfur Trioxide Damage to vegetation, property and health Colourless gas, highly soluble in water to form sulfurous acid SO 2 Sulfur Dioxide
32. ATMOSPHERIC CO 2 INCREASE OVER PAST 1000 YEARS Jacob: Intergovernmental Panel on Climate Change (IPCC) document, 2001 Concentration units: parts per million (ppm) number of CO 2 molecules per 10 6 molecules of air CO 2 CONCENTRATION IS MEASURED HERE AS MIXING RATIO
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40. Absorption Spectra of Atmospheric Gases Anthes, p. 55 CH 4 CO 2 N 2 O H 2 O O 2 & O 3 atmosphere WAVELENGTH (micrometers)
53. Anthropogenic perturbations to stratospheric ozone Role of CFC’s for reaction of Antarctic ozone hole Cl + O 3 ->ClO+O 2 ClO+NO 2 ->CLONO 2 General cycle of ozone destruction in the stratosphere:
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Editor's Notes
There are many chemical reactions involved in producing the photochemical smog. We only list a few important ones ( note the chemical symbols used here are not necessary exact, some are ‘descriptive’ only): (1) NO 2 + h NO + O ( h represents a photon) fast (2) O + O 2 + M O 3 + M ( M represents a neutral molecule) (3) O 3 + NO NO 2 + O 2 (4) O + HC (hydrocarbon) stable product + F.R. (free radical) slow (5) O 3 + HC S.P. + F.R. (6) F.R. + HC S.P. + F.R. ( Being a stable product doesn’t mean it is pleasant! It can be irritating to our body .) (7) F.R. + NO F.R. + NO 2 fast (8) F.R. + NO 2 Stable Product (PAN-Type, Peroxyacetyl Nitrate ) (9) F.R. + F.R. Stable product For our purpose here, the most important reactions are (1)-(3).
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