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20 Cards in this Set
- Front
- Back
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environmental effect of LA smog
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when LA still had agriculture...crop yields decreased
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natural ozone level
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20 ppb
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1975
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two way catalytic converted introduced
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primary pollutants in LA smog
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NO ad NO2- combustion
CO- combustion HC- industry, cars, plants (directly emitted) |
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secondary pollutants in LA smog
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ozone
particles (formed chemically) |
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why LA is perfect place to make ozone
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lots of cars
lots of sun sitting in a basin |
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carbon monoxide
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emitted combustion engines when there's little O2
levels affected by inversions, wind |
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CO highest @
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morning (lower inversion) and evening (stronger winds) rush hrs
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nitrogen oxides (NO, NO2)
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very hot temperatures (diesel engines- trucks)
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NOx chemistry
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NO and NO2 interconverted once a minute
need light! only happens during day |
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hydrocarbons (HC/VOC)
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plants
solvents fuel fumes unburned fuel |
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ozone
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in troposphere= bad
in stratosphere= good |
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9 hr difference btwn emission of primary and emergence of secondary pollutants (O3)
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...
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ozone formation in troposphere
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NO2 + sunlight --> O + NO
O2 + O --> O3 but gets converted back |
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levels of _____ determine ozone levels
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oxygen
UV radiation NOx, HC, CO + low inversions |
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OH radical
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react with nearly all molecules in atmosphere except permanent gasses, H2O, CO2
*cleaning agent of atmosphere *BUT also makes O3 |
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ozone machine (chart) 2 cycles turning
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OH --> HO2 and vice versa
NO --> NO2 and vice versa |
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shortcut to normal NOx cycle?
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ozone not destroyed?
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how does radical cycling stop?
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chemical reaction removing radicals, sun goes down
-goes into particles, drops (acid rain) |
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3 step ozone forming process
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1. fuel (CO/HC) degraded by reaction with OH radical
2. HO2 reacts w/ NO forming NO2, remakes OH 3. NO2 broken up w/ sunlight, makes O3 molecule |
