Unit 2: Lecture 13 - Air Pollution

particulate matter

soot, smoke, and ash from fuel (mainly coal) combustion; dust released during industrial processes; other solids from accidental and deliberate burning of vegetation

generated by human activity largely derived from point sources

long residence time

ozone layer

protective layer that absorbs ultraviolet radiation

ozone near the equator

ozone production rates are most rapid here, a consequence of strong sunlight

while

total ozone levels is highest toward poles (natural production and destruction rates & atmospheric circulation patterns)

ozone holes

extreme thinning of this protective shield of atmospheric ozone

how do CFCs destroy ozone?

1. UV radiation strikes a CFC molecule = chlorine is released

2. chlorine attacks ozone = forms chlorine monoxide

3. chlorine is freed again to destroy more ozone

→

a single chlorine atom can destroy many ozone molecules

acid rain

rain that is more acidic than normal

caused mainly by atmospheric sulfuric acid

acid rain effects

1. contaminate water supplies

2. damages structures and outdoor sculptures through its corrosive effects

thermal inversion

NORMALLY: within the lower atmosphere, air temperature decreases as altitude increases. warm, pollutant-bearing gases rise through the cooler, denser air.

there is a zone of relatively warmer air at some distance above the ground. pollutant gases are trapped below this warmer air layer.

control methods: air-pollutant emissions

1. trap the pollutants at the source

2. convert dangerous compounds to less harmful ones before effluent release

control method: particulate matter

filters

control method: carbon monoxide and nitrogen oxides

modifying the combustion process

lower combustion temperatures minimize the production of nitrogen oxides and moderate the production of carbon monoxide

carbon sequestration

storing carbon in some reservoir to remove it from atmospheric circulation

biological means: enhance natural carbon sinks; ex: reforestation

physical means: inject CO2 into geologic reservoirs, dissolve it in the ocean, or pipe into sea floor