Unit 7: Atmospheric Pollution

Notes

Unit 7: atmospheric pollution

7.1 - introduction to air pollutants

objective :

• identify the sources and effects of air pollutants

basics :

• write about specific air pollutants not just generally

• clean air act in 1970 give epa ability to monitor 6 air pollutants

• required to set limits (basically can punish)

sulfur dioxide :

• from coal combustion for electricity

• respiratory irritant

• smog

• acid precipitation

nitrogen oxides :

• nitric oxide and nitrogen dioxide

• all ff combustion (gas)

• warms ozone

• contributes to photochemical smog

• acid precipitation

carbon monoxide :

• incomplete combustion

• warms ozone

• lethal to humans

lead :

• metal plants

• waste incineration

• neurotoxicant

ozone (tropospheric) :

• photochemical oxidation of nitrogen dioxide

• respiratory irritant

• smog

• can cause plant damage

particulate matter :

• ff + biomass combustion

• respiratory irritant

• smog

air pollutants vs. greenhouse gasses :

• carbon dioxide is not one of the six criteria pollutants

• in 2007 the supreme court ruled the epa could regulate greenhouse gases so it did in 2009 (bc it's harmful to humans)

• carbon dioxide does not DIRECTLY lower air quality from a human health standpoint

• not toxic to organisms bc it's not damaging lung, eyes, leading to smog, decreased visibility

• leads to earth warming + environmental change DOES lead to human health consequences (basis for supreme court ruling in 2007)

• in apes, carbon dioxide is not an air pollutant

coal combustion :

• releases more air pollutants than any other ffs (35% of global electricity)

• releases carbon monoxide, carbon monoxide, sulfur dioxide, nitric oxide, nitrogen dioxide, mercury, arsenic, lead, and pm (which carries toxic metals)

• sulfur dioxide is released a lot in coal

• it is a respiratory irritant which worsens asthma + bronchitis

• creates sulfur aerosols which reflect the sun (lowers photosynthesis)

• forms sulfurous (grey) smog

• combines with water + oxygen in atmosphere to form acid rain

nitric oxides :

• released by combustion of anything (specifically ffs + biomass)

• nitric oxide forms when nitrogen combines with oxygen

• can become nitrogen dioxide if it reacts with ozone or oxygen again

• sunlight converts nitrogen dioxide back into nitric oxide

impacts :

• respiratory irritant

• leads to ozone formation, photochemical smog

• combines with water + oxygen in atmosphere to form nitric acid, acid precipitation

epa + lead :

• before caa (clean air act), lead was a common gasoline additive

• epa began to phaseout lead from gasoline in 1947

• vehicles made after 1974 had to have catalytic converters to reduce nitric oxide, nitrogen dioxide, carbon monoxide and hydrocarbon emissions

• also a neurotoxicant to humans (damages nervous system)

primary air pollutants :

• emitted directly from sources

• e.g. vehicles, power plants, volcanoes, forest fires

• nitric oxide, nitrogen dioxide, carbon monoxide, carbon dioxide, vocs (volatile organic carbons), sulfur dioxide, particulate matter, hydrocarbons

secondary air pollutants :

• have transformed in presence of sunlight, water, or oxygen

• occur more during the day bc of the sun

• tropospheric ozone

• sulfuric acid + sulfate

• nitric acid + nitrate

7.2 - photochemical smog

objective :

• explain the causes and effect of photochemical smog and methods to reduce it

precursors :

• ingredients for the smog

• nitrogen dioxide which is broken by sunlight into nitrogen oxide + oxygen

• oxide + oxygen = ozone

• volatile organic compounds (hydrocarbons) that bind with nitric oxide to form photochemical oxidants

• carbon-based compounds evaporating easily = gustation (e.g. gasoline, cleaning fluid, oil-based paints)

• ozone forms when nitric oxide is broken down by sunlight into nitrogen oxide + oxygen = ozone

• respiratory irritant in troposphere at earth's surface

• damaging to plant stomata, limiting growth

conditions :

• sunlight drives ozone formation bc more nitrogen dioxide is broken down

• also vocs evaporate faster so more smog formation

normal ozone formation :

• early morning traffic produced nitrogen dioxide

• sunlight breaks it into nitric oxide (no) + oxygen atom (o)

• the oxygen atom bonds with oxygen so ozone forms

• normally ozone formation peaks in afternoon, and at night the ozone breaks down and reforms nitrogen dioxide (cancels out)

photochemical smog formation :

• the normal ozone production stuff

• vocs bond with nitric oxide to form photochemical oxidants

• ozone cannot recombine with the nitric oxide bc vocs alr did

• leads to ozone buildup

• ozone + photochemical oxidants = photochemical smog

factors that increase formation of photochemical smog :

• increased traffic bc more nitrogen dioxide

• higher vocs emissions (e.g. gas stations, laundromats)

• more sunlight bc more ozone

• warmer temperatures bc vocs evaporate faster

• urban areas have more smog bc they have all of these factors

• more traffic, more nitrogen dioxide

• hotter temperatures bc low albedo of blacktop

• more vocs due to gas stations + factories

• more electricity demand so more nitrogen dioxide and nitric oxide emissions

environmental impacts :

• reduces sunlight so less photosynthesis

• damages stomata + irritates animal respiratory tracts

human impacts :

• for humans it worsens asthma, bronchitis, copd, eyes

economic impacts :

• increased health care costs to treat these

• lost productivity bc sick workers miss work or die

• decreases agricultural yields bc less sunlight reaching crops + damage to plant stomata

vehicle reduction :

• decreasing amt. of vehicles on the road (less nitrogen dioxide emissions)

• fewer vehicles = less gas = less vocs

energy reduction :

• increased electricity production from renewable sources bc no nitrogen dioxide + nitric oxide emissions

• natural gas power plants release a lot less nitrogen dioxide + nitric oxide than coal

7.3 - thermal inversion

objective :

• describe thermal inversion and its relationship with pollution

urban heat island effect :

• urban areas are hotter than surrounding suburban + rural areas

• lower albedo bc concrete + asphalt absorb more of the sun’s energy than areas with more vegetation

• absorbed sunlight is given off as infrared radiation

• vegetation reflects more sunlight

• evapotranspiration = water evaporating from surfaces and transpiration from plants carries heat from surface into the atmosphere

• cools off rural + suburban areas with more vegetation

thermal inversion :

• normally the atmosphere is warmest at earth’s surface + cools as altitude rises

• basically it just switches but cold air is still at the top

• bc of a warm air mass blocks the cold air

• it goes cold air -> warm air -> cooler air

• also bc of hot urban surfaces cooling overnight

• bc warm air rises air convection carries air pollutants away from earth’s surface

effects :

• air pollutants are trapped closer to earth

• respiratory irritation = asthma flare ups leading to hospitalizations, worsened copd, emphysema (obstructive lung disease)

• decreases tourism revenue

• decreased photosynthesis

7.4 - atmospheric carbon dioxide and particulates

natural sources :

• lightning strikes convert n2 in atmosphere into nitrogen dioxide + nitric oxide

• forest fires make carbon monoxide, particulate matter, nitrogen dioxide + nitric oxide

• plants emit volatile organic compounds (e.g. terpenes + ethylene from pine, fir, spruce, etc. + smoky mountains)

• volcanoes emit sulfur dioxide, particulate matter, carbon monoxide, and nitrogen oxides

living sources :

• respiration bc everything releases carbon dioxide through respiration

• not that major though

• natural particulate matter sources = sea salt, pollen, ash

• leads to haze (scattering of sunlight + reduced visibility)

• aerobic decomposition = decomposition of organic matter by bacteria in the presence of oxygen it releases carbon dioxide

• anaerobic decomposition = decomposition of organic matter by bacteria decomposers in low or oxygen-free conditions + releases methane

particulate matter :

• any solid or liquid particles suspended in air (also called particulates)

pm10 :

• pm10 micrometers

• particles or droplets like dust, pollen, ash

• too small to be filtered out by nose hairs + trachea cilia

• can irritate respiratory tract + cause inflammation

pm2.5 :

• pm2.5 micrometers

• more concerning bc can go deeper into lungs

• associated with chronic bronchitis + increased risk of lung cancer

• generally degrade lungs + respiratory tract

7.5 - indoor air pollutants

objective :

• identify indoor air pollutants

developing countries :

• developing nations rely on subsistence fuels (wood, manure, charcoal)

• biomass releases carbon monoxide, particulate matter, nitrogen oxides, and volatile organic compounds (can also cause deforestation)

• often combusted indoors with poor ventilation

• estimated that 3 billion people globally cook with subsistence fuels

• leads to 4 million deaths annually

developed countries :

• developed nations use more commercial fuels (coal, oil, natural gas)

• burned in well ventilated areas (e.g. furnaces, stoves)

• major indoor air pollutants in developing countries is from cleaning supplies, insulation, lead paint

pm + asbestos :

• e.g. smoke from indoor biomass combustion + asbestos

• asbestos is a long, silicate particle that was used in insulation

• now it is linked in lung cancer

• phased out of use but in older buildings

• not dangerous until asbestos particles enter air

• should be removed by professionals with ventilation in the area

• plastic to seal off area from rest of building

carbon monoxide :

• produced by incomplete combustion of any fuel source

• asphyxiant = causes suffocation due to binding to hemoglobin in blood which displaces oxygen

• lethal to humans in high concentrations especially with poor ventilation

• developed nations = can be detected by carbon monoxide detectors

• developing nations = emitted from biomass combustion for heating/cooking

volatile organic compounds :

• chemicals used in variety of home products that easily vaporize, enter air, and irritate stuff

• adhesives/sealants = chemicals used to glue carpet down, hold furniture together + have formaldehyde (carcinogenic)

• cleaners = febreeze, ecolab

• plastics also can

radon gas :

• radioactive gas released by decay of uranium naturally in rocks underground

• enters home through foundationary cracks + disperses up

• can also seep into groundwater sources + enter body through drinking water

• second leading cause of lung cancer after smoking

• epa recommends testing homes with airborne radon monitor

• sealing cracks in foundation can prevent it from entering + increasing ventilation in the home can disperse if detected

dust + mold :

• dust = dead human skin cells

• settles naturally in homes, can enter respiratory tract

• mold develops in areas that are dark and damp and aren’t well ventilated

• black mold releases spores in air which is harmful to the respiratory system

• can be removed by physically cleaning it out + fixing the leak forming it

lead :

• found in paint in old homes

• paint chips off walls/windows and is eaten by small children

• or inhaled as bust

• lead water pipes can also release lead into drinking water sources

• less common than lead paint

• in children it is a neurotoxicant

7.6 - reduction of air pollutants

objective :

• explain how air pollutants can be reduced at the source

reducing emissions :

• drive less, walk/bike/bus mor

• conserve electricity

• eat more plants, less meat

• renewable energy (solar, wind, hydroelectric)

clean air act :

• allows epa to set levels for air pollutants

• monitor emissions and hurt companies who don’t comply

cafe vehicle standards :

• corporate average fuel economy

• requires vehicle manufacturers to work to make more efficient vehicles

• more efficiency vehicles burn less gasoline

pollution credits :

• if you bring levels low you get credits

• incentivises to release few credits

• how tesla is profitable bc you can sell the credits

vapor recovery nozzle :

• captures hydrocarbon volatile organic compounds released from gasoline

• reduces volatile organic compounds (less smog + irritants)

• also reduces benzene (carcinogenic compound)

catalytic converter :

• required on all vehicles after 1975

• filters exhaust coming out of engine

crushed limestone :

• for sulfur

• made of calcium carbonate

• gets trapped as calcium sulfate

• can be used for gypsum wallboards or sheetrock

fluidized bed combustion :

• for nitrogen

• blasting in jets of air

• changes the nitrogen into a bubbling bed

• allows coal to be combustion at lower temperatures (less nitrogen oxides)

dry scrubbers :

• large column with chemicals that reacts with air pollutants

• traps the air pollutants

wet scrubbers :

• has some chemical agent that traps the chemicals

• also has a mist apparatus

• grabs on to particulate matter

electrostatic precipitator :

• power plant emissions go through a device which gives the particles a negative charge + then they stick to positively charged plates to be trapped

baghouse filter :

• large fabric bag filters that trap particulate matter as air from industrial processes

• pm is collected then taken to the landfill

7.7 - acid deposition

objective :

• describe acid deposition

• describe the effects of acid deposition on the environment

sources of nitrogen oxides + sulfur dioxide :

• primary pollutants that cause most acid precipitation

• sulfur dioxide = coal fired power plants, diesel

• nitrogen oxides = vehicle emissions

limiting acid rain :

• higher cafe standards

• more public transit

• renewable energy source

• more efficient electricity use

• since clean air act acid deposition increased

chemistry :

• no2 + so2 react with o2 and water in the atmosphere forming nitric + sulfuric acid

• basically the acids can separate into ions which then join the rain

soil/water acidification :

• acidity = higher h+ on concentration, lower ph

• h+ displace nutrients from the soil

• also make toxic metals more soluble in water

• can slow growth or kill plants + animals living in the soil or water

mitigating acid rain :

• limestone is a natural base that can neutralize acidic soil/water

• calcium carbonate reacts with h+ ions to neutralize (move ph closer to seven) the acidic water

• regions have natural limestone in bedrock (natural)

• humans can simulate this by spreading limestone powder over things

• acid rain can also corrode human structures

• obviously limit so2 + nox

7.8 - noise pollution

objective :

• describe human activities that result in noise pollution and its effects

urban noise pollution :

• any sound loud enough to cause physiological stress

• construction, transportation, manufacturing plants, domestic activity (loud neighbors, lawn mowing, home projects)

wildlife effects :

• animals can also suffer from hearing loss

• caterpillars hearts beat faster when exposed to highway noise pollution

• lack of hearing can also make predators not find prey

aquatic effects :

• from ship engines, sonar, oil, gas ships

• physiological stress = faster heart rate, hearing loss

• whales rely on vocal communication so hearing loss = deadly

• seismic surveying = ships sending huge air blasts into the water to see if there is oil + is really loud

• obviously disrupts the aquatic life bc causes hearing loss