NRES 351: exam 1 (tropospheric chem)

classical smog (London smog)

-combustion of high sulphur coal
-Constiuents: soot (fly ash, So2, Nacl, CasSo4)

photochemical smog

-petroleum combustion
-Constituents: NOx, VOCs, ozone, PANs, aldehyde

Particle size & respiratory toxicity

smaller particles are deposited deeper in the respiratory tract

Solubility & respiratory toxicity

more soluble particles are less likely to penetrate deep lung tissues
-SO2 is water soluble, but NO2 and O3 are not

Henry's Law (Kh)

the solubility of a gas in a liquid is directly proportional to the partial pressure of that gas on the surface of the liquid

Classic smog formation

Carbon based components
-Combustion of coal in prescence of low O2 emits CO2, CO, & C
Sulphur based components
-Combustion of S in coal emits SO2
-Water in the atmosphere oxidizes SO2 to SO3
-Reacts with O2 in atmosphere to form sulphuric acid

Stokes law

speed at which particles of sediment drops based on radius and density; bigger particles drop faster

Formation of photochemical smog

1. Combustion of N2 to form NO
2. Oxidation of NO to form NO2
3. Photolysis of NO2 to form O3
4. Hydroxyl radical formed from O3
5. OH radical reacts w/ hydrocarbons to form aldehydes, PANS, and haze

Classic vs. photochemical smog

Reductive vs. Oxidative

Ozone cracking

traces of ozone in the atmosphere attack double bonds in the chains of the materials

Decomposition of pigment by O3

Color changes of natural colorant/paper systems during exposure to 0.40 ppmv

SO2 impact on plant tissue

Oxidized to sulfate/sulfite
-Disrupts photosynthesis/metabolism

CaSo4 impact on cement

Sulfates can cause chemical changes of the cement constituents (crystallization and recrystallization new minerals), causing damage to porous cementitious materials