chapter 15: air pollution
Big ideas: air is shared by everyone on the planet, crosses international borders without consent, impacts innocents with little power.
6 major pollutants: “criteria pollutants”
Mnemonic: SOX/NOX, CO/O3, PM/Pb
2007 add CO2, VOC, Hg
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SO2
From Methionine (amino acid in living things) in fossil fuels
Combines with water in the air to make H2SO4 (sulfuric acid)
NOx
Various forms of oxidized nitrogen, which alone is inert and makes up 78% of the atmosphere at sea level
From high temperature combustion (e.g. auto engines, esp. high efficiency ones, which burn at higher temps)
Also from decomposition of fertilizers (e.g. Ammonium Nitrate)
CO carbon monoxide
Emission from car exhaust, or other incomplete combustion:
C + O2 —> CO2
If not enough O2, then CO forms
Toxic, permanently attaches to hemoglobin rendering it useless for respiration. 30 day life cycle for hemoglobin
See also CO2 and climate change, > 400ppm since 2012, 407ppm today
Air Quality monitoring: Purple Air:
Check out other locations...
PM
PM2.5 is most dangerous, smaller particles lodge deep in the lungs, beyond ability of pulmonary cilia to flush out
PM5, PM10 larger particles
Main cause: coal fired power plants, diesel engines, oil fired power plants (soot)
See also vog: PM2.5 particles of ash with SO2 dissolved in water droplets: physical abrasive + corrosive acid = respiratory damage
Ozone
Ozone in stratosphere is good, in troposphere bad
Stratospheric ozone is necessary to filter UV radiation. CFC (chloro-fluro-carbons) destroy this layer this way:
This caused an ozone hole over antarctica:
How did we solve this? 1987 Montreal Protocol:
Tropospheric ozone causes lung and eye irritation, and is toxic to some organisms
Pb
Gasoline additive (tetraethyl lead, improves octane rating cheaply), replaced by other worse carcinogenic (cancer causing) chemicals like MTBE:
https://en.wikipedia.org/wiki/Methyl_tert-butyl_ether
Decreases mental capacity (e.g. Roman insanity theory)
Found in coal smoke, along with Mercury and other heavy metals. Sludge from mining is worse.
VOC
Volatile organic compounds, e.g. gasoline vapors (why your gas cap must be on or you get a dashboard warning):
https://en.wikipedia.org/wiki/Volatile_organic_compound
Smog and other photochemical reactions:
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Primary and secondary pollutants:
Secondary pollutants: need a chemical reaction (often energy from sunlight) to form (see figures above)
See PANs: Peroxyacyl nitrates: formed from VOCs, NOx
https://en.wikipedia.org/wiki/Peroxyacyl_nitrates
Thermal inversions: London fog, US, Donora, PA 1948 k.20, sick 7000
1952 London 4000-12,000 dead, three nights
Mexico city 1996 300 dead, 400K sick
How?
Normally, the sun heats the surface, warming the air there, which rises. Cooler air aloft then falls to replace this rising air.
In an inversion, warmer air aloft traps the air at the surface (no temperature difference, so no mixing), causing the pollution to be trapped in the lower levels. Most dangerous in valleys or bowl shaped cities (London, Mexico City, Denver, Donora).
Los Angeles has severe smog in the daytime, when hotter air draws in ocean air ("onshore breeze"), but the cycle reverses at night when the water is warmer than the land, so they have an "offshore breeze".
Acid rain: plants, fish, structures. Check this out:
SO2 + O2, water = H2SO4 (sulfuric acid)
NO3 + O2, water = HNO3 (nitric acid)
“Acid snow” yes, acid snow...
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W. VA had rain more acidic than stomach acid in the 1970's
Important: Know how a power plant air scrubber works (just like the nuclear plant diagram)
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IAP-indoor air pollution
Leading cause of death in LDC (women)
Burning manure for fuel, open pit fires, CO, PM10
Sick building syndrome: formaldehyde, CO2, VOC
Main culprits: VOC, CO, Radon, Lead, formaldehyde, asbestos, PM10
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Asbestos-asbestosis, mesothelioma
Radon 222-lung cancer (smoke demo-lungs)
AIR QUALITY LABS
• Air Quality: Air quality can be assessed using various
methods.
• Particulates: Sticky paper can be used to collect
air particulates from various sources, and then the
paper can be examined under a microscope. It is
not possible to see the smallest particulates, but
they do color the white paper.
• Ozone: In this lab, an ecobadge or a homemade
potassium iodide gel sampler is hung or worn in
order to collect data on tropospheric ozone. The
badge or KI sample changes color in the presence
of ozone and becomes more intensely colored as
the amount of ozone increases.
• Carbon dioxide: In this lab, a commercial sampling
device is used to determine the amount of
carbon dioxide in an air sample. Car exhaust,
burning tobacco, or other pollutants can also be
sampled.
Pollution roundup:
Chapter 8 of Princeton Review for AP:
http://physics.hpa.edu/physics/apenvsci/apes_exam_prep/apes_princeton/ch08-pollution.pdf
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