APES unit 7 (atmospheric pollution)

FRQ tip about air pollution

write about air pollutants, not just air pollution as an idea

clean air act (1970) (CAA)

identified 6 criteria air pollutants that the EPA is required to set acceptable limits for, monitor, and enforce

SO2

sulfur dioxide; from coal combustion; respiratory irritant, smog, and acid precipitation

NOx

nitrogen oxides (NO and NO2); all ff combustion; O3, photochem smog, acid precipitation

CO

carbon monoxide; incomplete combustion; O3; lethal to humans

PM

particulate matter; ff/biomass combustion; respiratory irritant, smog

O3

ozone (tropospheric); photochemical oxidation of NO2; respiratory irritant, smog, plant damage

Pb

lead; metal plants, waste incineration; neurotoxicant

air pollutants vs greenhouse gasses

CO2 doesn't directly lower air quality so not typically considered an air pollutant; air pollutants lower air quality, greenhouse gasses don't

coal combustion in polluting air

releases more air pollutants than other ffs; ~35% of global electricity

impacts of SO2

respiratory irritant, sulfur aerosols block incoming sun, forms smog, acid precipitation

impacts of NOx

respiratory irritant, leads to O3 formation, acid precipitation

lead used to be added to ________

gasoline, but the EPA began the phaseout of lead from gasoline in 1974

primary air pollutants

emitted directly from sources such as vehicles, power plants, factories, or natural sources; NOx, CO, CO2, VOCs, SO2, PM, hydrocarbons

secondary air pollutants

primary pollutants that have transformed in presence of sunlight, water, O2; occur more during the day; tropospheric O3, sulfuric acid, sulfate, nitric acid, nitrate

precursors to photochemical smog

NO2 broken by sunlight into NO + O; volatile organic compounds that bind with NO and form photochemical oxidants; forms when NO2 is broken by sunlight and free O binds to O2

conditions for photochemical smog

sunlight (drives O3 formation by breaking down NO2) and warmth (hotter atm. temp. speeds O3 formation, evap. of VOCs and thus smog formation)

peak O3 formation time

in the afternoon when sunlight is most direct and NO2 emissions from morning traffic have peaked

photochemical smog formation

NO2 is broken into NO + O by the sun; NO bonds with VOCs to form photochemical oxidants; free O bonds with O2 to form O3; instead of reacting with the NO, O3 just builds up; O3 and photochemical oxidants combine to form photochemical smog

factors that increase photochemical smog formation

more sun, warmer temps., higher VOCs emissions, more vehicle traffic

environmental impacts of photochemical smog

reduces sunlight (limits photosynthesis); O3 damages plant stomata and irritates animal respiratory tracts

human impacts of photochemical smog

respiratory irritant (worsens asthma, bronchitis, COPD); irritates eyes

economic impacts of photochemical smog

increased healthcare cost to treat health problems; lost productivity due to sick workers missing work or dying; decreased ag. yields due to less sunlight and damage to plant stomata

ways to reduce photochemical smog through vehicles

decreasing the number of vehicles on the road decreases NO2 emissions; fewer vehicles = les gas = fewer VOCs; carpooling, public transport, biking, walking, working from home

ways to reduce photochemical smog through energy production

increased electricity production from renewable sources that don't emit NOx (solar, wind, hydro); natural gas power plants release far less NOx than coal

thermal inversion

cold air gets trapped at the surface, and warm air is above it so air convection carries air pollutants higher into the atmosphere

effects of thermal inversion

air pollutants trapped closer to earth; respiratory irritation; decreased tourism revenue; decreased photosynthetic rate

natural sources of air pollutants

lightning strikes, forest fires, plants, volcanoes

natural sources of CO2 and PM

respiration, sea salt, pollen, ash, dust, aerobic decomp., anaerobic decomp.

aerobic decomposition

decomposition of organic matter by bacteria and decomposers in the presence of oxygen (releases CO2)

anaerobic decomposition

decomposition of organic matter by bacteria and decomposers in low or oxygen-free conditions (released CH4)

particulate matter (PM)

solid or liquid particles suspended in air (aka particulates)

PM10

< 10 micrometers particulates (Ex: dust, pollen, mold, ash etc.)

effects of PM10 on humans

too small to be filtered out by nose hairs and trachea cilia; can irritate respiratory tract and cause inflammation

PM2.5

< 2.5 micrometers, from combustion (especially vehicles)

effects of PM2.5 on humans

more likely to travel deep into the lungs due to smaller size; associated with chronic bronchitis and increased risk of lung cancer

major indoor air pollutants in developed nations come from ________

chemicals in products (adhesives in furniture, cleaning supplies, insulation, lead paint)

carbon monoxide (CO) as an indoor air pollutant

produced by incomplete combustion of basically any fuel; it's an asphyxiant (causes suffocation due to CO binding to hemoglobin in blood, displacing O2)

VOCs as an indoor air pollutant

from adhesives, sealants, formaldehyde, cleaners, plastics, fabrics, etc

radon gas as an indoor air pollutant

radioactive gas released by decay of uranium naturally found in rocks underground (especially granite); seeps through cracks in homes

dust and mold as an indoor air pollutant

natural indoor air pollutants that can worsen asthma, bronchitis, COPD, emphysema

lead as an indoor air pollutant

found in paint in old homes; paint chips off and is eaten by small children or inhaled as dust; lead pipes; damages central nervous system of children

pollution credits

companies that reduce emissions well below EPA-set levels earn pollution credits and can sell them to companies that release more than the acceptable levels

corporate average fuel economy (CAFE) standards

requires the entire US 'fleet' of vehicles to meet certain average fuel, which makes them more efficient, reducing NOx, PM, CO, and CO2 release

vapor recovery nozzle

capture hydrocarbon VOCs released from gasoline fumes during refueling; reduces VOCs

catalytic converter (CC)

converts NOx, CO, and other hydrocarbons from cars into CO2, N2, O2, and H2O

crushed limestone to reduce SO2

crushed coal mixed with limestone before being burned; calcium carbonate in limestone combines with SO2, reducing SO2 emissions

fluidized bed combustion to reduce NOx

fluidizing jets of air pumped into combustion 'bed'; jets of air bring more O2 into rxn, making combustion more efficient and bringing SO2 into more contact with calcium carbonate in limestone

dry scrubbers

large column/tube/pipe filled with chemicals that absorb or neutralize oxides from emissions

wet scrubbers

same thing as dry scrubbers, but also include mist nozzles that trap PM in water droplets

electrostatic precipitator

power plant/factory emissions passed through device with a negative charged electrode, giving particles a negative charge; those particles stick to positively charged collection plates, trapping them

baghouse filter

large fabric bag filters that trap PM as air from combustion/industrial processes passes through

major sources of SO2

coal fired power plants, metal factories, vehicles that burn diesel fuel

major sources of NOx

vehicle emissions, diesel generators, coal power plants

how to limit acid rain

reduce NOx and SO2 emissions (higher CAFE standards, more public transit, renewable energy sources, more efficient electricity use, etc.)

how acid rain is made through NO2

NO2 + O2 and H2O = NHO3 (nitric acid) -> NO3- and H+ ion

how acid rain is made through SO2

SO2 + O2 and H2O = H2SO4 (sulfuric acid) -> H2SO2 and 2 H+ ions

why do nitric and sulfuric acid split into ions

they dissociate in the presence of H2O

higher H+ concentration = lower ________

pH

environmental effects of acid rain

soil/water acidification, pH tolerance

soil/water acidification

H+ ions displace/leech other pos. charged nutrients from soil and also make toxic metals more soluble in soil and water (slow growth or kill plants and animals)

how pH tolerance is affected by acid rain

as pH decreases outside optimal range for a species, the pop. declines

indicator species

species that can be surveyed and used to determine conditions of an ecosystem

mitigating acid rain

limestone reacts with H+ ions, which 'neutralizes' the soil

noise pollution

any noise at great enough volume to cause physiological stress (difficulty communicating, headaches, confusion) or hearing loss

noise pollution effects on land wildlife

disrupts animal communication migration, and damage hearing

noise pollution effects on aquatic wildlife

hearing loss, disrupted communication, mating calls, predator and prey navigation

sources of aquatic noise pollution

ship engines, military sonar, and seismic air blast