Typical mixing ratios for some compounds of environmental importance.
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Transcript of Typical mixing ratios for some compounds of environmental importance.
Typical mixing ratios for some compounds of environmental importance
Carbon dioxide 355 ppm Carbon monoxide 100 ppb to 20 ppm Ozone 1 to 100 ppb Methane 1.72 ppm Nonmethane hydrocarbon 1 ppt to < 1 ppb Nitric oxide (NO) 5 ppt to 1 ppb Nitrogen dioxide (NO2) 1 to 150 ppb Nitrous oxide (N2O) 310 ppb Sulfur dioxide 1 to 100 ppb CFCl3 (Freon 11) 200 ppt CF2Cl2 (Freon 12) 350 ppt
atmospheric pressure
The atmospheric pressure is the weight exerted by the overhead atmosphere on a unit area of surface
A Bh
vacuum
Mercury barometer
ghP HgA
Units for pressure
• International System of Units: Pascal (N/m2)• Hectopascal (hPa)• mm Hg or Torr• Millibar (mbar)• psi (lb/in2)
1 atm = 1.01325 x 105 Pascal (Pa) = 1.01325 x 103hPa
1 atm = 760 mmHg = 760 Torr1 atm = 1013.25 mbar
1 atm = 14. 7 psi
Ultraviolet protection by ozone
Ozone absorbs UV light in the solar irradiation that is harmful to life
• The major natural carrier of chlorine to the stratosphere is CH3Cl
CF2Cl2 2 Cl. + other products
CFCl3 3 Cl. + other products
CO formation from methane oxidation
CH4 + OH CH3 + H2O
+O2
C O
H
H
H
CH3OO
NONO2
+O2
CH H
O
+ HO2
hv
H
O+ HO2
O2
HO2
CO
Sulfur gases
-2 +4 +6H2SHydrogen sulfide(CH3)2SDimethylsulfide (DMS)CS2Carbon disulfideCOSCarbonyl sulfide
SO2Sulfur dioxide
H2SO4Sulfuric acidSO4
2-
Sulfate
Decreasing oxidation number (reduction reactions)
Increasing oxidation number (atmospheric oxidation)
Necessary ingredients for ozone formation
CH4 + .OH + O2 CH3OO. + H2O
CH3OO. + NO CH3O. + NO2
CH3O. + O2 HCHO + HO2.
HO2. + NO .OH + NO2
NO2 + h NO + O (2x)
O + O2 + M O3 + M (2x)
Net: CH4 + 4 O2 HCHO + H2O + 2 O3
VOC
Sunlight
Greenhouse
Glass, the material that greenhouse is made of, 1) transmit short-wavelength visible light, 2) absorbs and redirects the longer wavelengths of energy. These two aspects make the greenhouse warmer than outside air temperature.
Natural Greenhouse effect
The natural greenhouse effect causes the mean temperature of the Earth's surface to be about 33oC warmer than it would be if natural greenhouse gases were not present.
Enhanced greenhouse effect
When concentrations of greenhouse gases increase, more infrared radiation is returned toward the earth and the surface temperature rises.