Air Pollution Notes

7.1 Introduction to Air Pollution (Pollutants)

Learning Objective: STB-2.A: Identify the sources and effects of air pollutants.
Essential Knowledge:
- STB-2.A.1: Coal combustion releases air pollutants including carbon dioxide, sulfur dioxide, toxic metals, and particulates.
- STB-2.A.2: The combustion of fossil fuels releases nitrogen oxides into the atmosphere. They lead to the production of ozone, formation of photochemical smog, and convert to nitric acid in the atmosphere, causing acid rain. Other pollutants produced by fossil fuel combustion include carbon monoxide, hydrocarbons, and particulate matter.
- STB-2.A.3: Air quality can be affected through the release of sulfur dioxide during the burning of fossil fuels, mainly diesel fuels.
- STB-2.A.4: Through the Clean Air Act, the Environmental Protection Agency (EPA) regulated the use of lead, particularly in fuels, which dramatically decreased the amount of lead in the atmosphere.
- STB-2.A.5: Air pollutants can be primary or secondary pollutants.
Air Pollution Basics
- Coal combustion (electricity): Responsible for respiratory irritation, smog, and acid precipitation.
- Fossil fuel/biomass combustion: Responsible for respiratory irritation and smog.
- $SO_2$ (Sulfur dioxide).
- Nitrogen Oxides ( $NO$ & $NO_2$ ).
- Carbon Monoxide ( $CO$ ).
- Particulate Matter ( $PM$ ).
- Ozone (tropospheric) ( $O_3$ ).
- Lead ( $Pb$ ).
- All FF combustion (gas esp.): Ozone, photochemical smog, and acid precipitation.
- Incomplete combustion: Ozone, lethal to humans.
- Photochemical oxidation of $NO_2$ : Respiratory irritation, smog, and plant damage.
- Metal plants, waste incineration: Neurotoxicant.
Clean Air Act (1970): Identified 6 criteria air pollutants that the EPA is required to set acceptable limits for, monitor, and enforce.
Air Pollutants vs. Greenhouse Gasses
- $CO_2$ is NOT one of 6 criteria pollutants in Clean Air Act (although 07’ SC ruling found EPA could regulate greenhouse gases and it began doing so in 09’)
 - $CO_2$ does not directly* lower air quality from a human health standpoint
 - Not toxic to organisms to breath
 - Not damaging to lungs/eyes
 - Does not lead to smog, decreased visibility
 - $CO_2$ is a greenhouse gas; it does lead to earth warming, and thus env. and human health consequences (basis for SC ruling in 07’)
- Bottom line: In APES, $CO2$ has not typically been included on FRQ scoring guides as an air pollutant (stick to sure fire air pollutants on FRQs: $SO2$ , $NOx$ , $O3$ , PM)
Coal Combustion
- Releases more air pollutants than other FFs; ~35% of global electricity.
- Releases $CO$ , $CO2$ , $SO2$ , $NO_x$ , toxic metals (mercury, arsenic, lead), and PM (often carries the toxic metals).
 - Impacts of $SO_2$
 - Respiratory irritant (inflammation of bronchioles, lungs), worsens asthma & bronchitis.
 - Sulfur aerosols (suspended sulfate particles) block incoming sun, reducing visibility & photosynthesis.
 - Forms sulfurous (grey) smog.
 - Combines with water & $O_2$ in atmosphere to form sulfuric acid → acid precipitation.
Nitrogen Oxides ( $NO_x$ )
- Released by combustion of anything, especially FFs & biomass.
 - $NOx$ refers to nitrogen oxides (both $NO$ , and $NO2$ ).
 - $NO$ forms when $N2$ combines with $O2$ (esp. during combustion).
 - $NO$ can become $NO2$ by reacting with $O3$ or $O_2$ .
 - sunlight converts $NO_2$ back into $NO$ .
- Env. & Human Health Impacts
 - Resp. irritant.
 - Leads to tropospheric ozone ( $O_3$ ) formation, which leads to photochemical smog.
 - Combines with water & $O_2$ in atm. to form nitric acid → acid precipitation.
EPA & Lead
- Before CAA, lead was a common gasoline additive; EPA began phaseout of lead from gasoline in 1974.
  - Vehicles made after 1974 are required to have catalytic converters to reduce $NO_x$ , $CO$ and hydrocarbon emissions (lead damages catalytic converters).
- Also a known neurotoxicant (damages nervous systems of humans).
Primary vs. Secondary Air Pollutants
- Primary
 - Emitted directly from sources such as vehicles, power plants, factories, or natural sources (volcanoes, forest fires).
 - $NOx$ , $CO$ , $CO2$ *, VOCs, $SO_2$ , PM, hydrocarbons.
- Secondary
 - Primary pollutants that have transformed in presence of sunlight, water, $O_2$ .
 - Occur more during the day (since sunlight often drives formation).
 - Tropospheric $O_3$ (Ozone).
 - Sulfuric acid ( $H2SO4$ ) & sulfate (SO_4^{2-}$).
 - Nitric acid (HNO3) & nitrate (NO3^-$).

7.2 Photochemical Smog

Learning Objective: STB-2.B: Explain the causes and effects of photochemical smog and methods to reduce it.
Essential Knowledge:
- STB-2.B.1: Photochemical smog is formed when nitrogen oxides and volatile organic hydrocarbons react with heat and sunlight to produce a variety of pollutants.
- STB-2.B.2: Many environmental factors affect the formation of photochemical smog.
- STB-2.B.3: Nitrogen oxide is produced early in the day. Ozone concentrations peak in the afternoon and are higher in the summer because ozone is produced by chemical reactions between oxygen and sunlight.
- STB-2.B.4: Volatile Organic Compounds (VOCs), such as formaldehyde and gasoline, evaporate or sublimate at room temperature. Trees are a natural source of VOCs.
- STB-2.B.5: Photochemical smog often forms in urban areas because of the large number of motor vehicles there.
- STB-2.B.6: Photochemical smog can be reduced through the reduction of nitrogen oxide and VOCs.
- STB-2.B.7: Photochemical smog can harm human health in several ways, including causing respiratory problems and eye irritation.
Precursors
- $NO2$ | Broken by sunlight into $NO$ + $O$ (free $O + O2 → O_3$ )
- VOCs | Volatile organic compounds (hydrocarbons) that bind with $NO$ & form photochemical oxidants
- $O3$ | Forms when $NO2$ is broken by sunlight & free $O$ binds to $O_2$
- Sunlight | Drives $O3$ formation by breaking down $NO2 → NO + O$ ; then free $O$ atom binds with $O_2$
- Warmth | Hotter atm. temp. speeds $O_3$ formation, evaporation of VOCs & thus smog formation
- VOCs
 - Carbon-based compounds that volatilize (evaporate) easily (this makes them “smelly”).
 - Sources: gasoline, formaldehyde, cleaning fluids, oil-based paints, even coniferous trees (pine smell).
 - Resp. irr. in troposphere (@earth’s surface).
 - Damaging to plant stomata, limiting growth.
Normal $O_3$ Formation
- Morning commute leads to high $NO_2$ levels from car exhaust
- Sunlight breaks $NO_2$ into $NO + O$
- $O$ bonds with $O2$ to form $O3$
- At night, $O3$ reacts with $NO$ to form $NO2$ and $O2$ once again; $O3$ levels drop overnight
- $O3$ formation typically peaks in afternoon when sunlight is most direct and $NO2$ emissions from morning traffic have peaked
Photochemical Smog Formation
- Sunlight breaks $NO_2$ into $NO + O$
- $O$ bonds with $O2$ to form $O3$
- VOCs bond with $NO$ to form photochemical oxidants
- Without $NO$ to react with, $O3$ builds up instead of returning to $O2$ & $NO_2$ overnight
- $O_3$ combines with photochem. oxidants ( $NO$ + VOCS) to form photochemical smog
Factors That Increase Smog Formation
- Higher VOCs emissions (gas stations, laundromats, petrochem. & plastic factories)
- Increased vehicle traffic; increases $NO2$ emissions & therefore $O3$ formation
- More sunlight (summer, afternoon) = more $O_3$
- Warmer temperature, speedes evap. of VOCs and rxn that lead to $O_3$
- Urban areas have more smog due to all of these factors
 - More traffic → more $NO_2$
 - Hotter temps due to low albedo of blacktop
 - More VOCs due to gas stations & factories
 - More electricity demand; more $NO_x$ emissions from nearby power plants
Impacts & Reduction of Smog
- Env. | Reduces sunlight; limiting photosynthesis; $O_3$ damages plant stomata and irritates animal resp. tracts
- Humans | Resp. irritant; worsens asthma, bronchitis, COPD; irritates eyes
- Economic | Increased health care costs to treat asthma, bronchitis, COPD; Lost productivity due to sick workers missing work or dying; Decreased ag. yields due to less sunlight reaching crops & damage to plant stomata
- Vehicles | Decreasing the number of vehicles on the road decreases $NO_2$ emissions; Fewer vehicles = less gas = fewer VOCs
- Energy | Increased electricity production from renewable sources that don’t emit $NOx$ (solar, wind, hydro); Nat. gas power plants release far less $NOx$ than coal
- Reduction - Carpooling, public transport, biking, walking, working from home.

7.3 Thermal Inversion

Learning Objective: STB-2.C: Describe thermal inversion and its relationship with pollution.
Essential Knowledge:
- STB-2.C.1: During a thermal inversion, the normal temperature gradient in the atmosphere is altered as the air temperature at the Earth's surface is cooler than the air at higher altitudes.
- STB-2.C.2: Thermal inversion traps pollution close to the ground, especially smog and particulates.
Urban Heat Island Effect
- Urban areas tend to have higher surface & air temperature than surrounding suburban and rural areas due to:
  - Lower albedo; concrete & asphalt absorb more of sun’s energy than areas with more vegetation (absorbed sunlight is given off as IR radiation - heat)
  - Less evapotranspiration; water evaporating from surfaces and transpiration from plants carries heat from surface into the atmosphere
    - This cools off rural & suburban areas which have more vegetation
Thermal Inversion
- Normally, the atmosphere is warmest at earth’s surface, and cools as altitude rises
  - Because warm air rises, air convection carries air pollutants away from earth’s surface & distributes them higher into the atmosphere
- During a thermal inversion, a cooler air mass becomes trapped near earth’s surface (Inverting normal gradient)
  - Due to a warm front moving in over it
  - Or due to hot urban surfaces cooling overnight while IR radiation absorbed during the day is still being released
  - Because cold air at the surface is trapped beneath the warmer mass above, convection doesn’t cary pollutants up & away
Effects of Thermal Inversion
- Air pollutants (smog, PM, ozone, $SO2$ , $NOx$ ) trapped closer to earth
- Respiratory irritation: asthma flare ups leading to hospitalization, worsened COPD, emphysema
- Decreased tourism revenue
- Decreased photosynthetic rate

7.4 Atmospheric $CO_2$ & PM

Learning Objective: STB-2.D: Describe natural sources of $CO_2$ and particulates.
Essential Knowledge:
- STB-2.D.1: $CO_2$ appears naturally in the atmosphere from sources such as respiration, decomposition, and volcanic eruptions.
- STB-2.D.2: There are a variety of natural sources of particulate matter.
Natural Sources of Air Pollutants
- Lightning Strikes Convert $N2$ in atm. to $NOx$
- Forest Fires
 - Combustion of biomass also releases $CO2$ & $H2O$ vapor (greenhouse gasses).
 - $SO2$ , PM, $CO$ , $NOx$
- Volcanoes
- Plants emit VOCs
 - Ex: terpenes & ethylene from pine, fir, spruce trees
 - This forms natural photochemical smog in Smoky Mountains
Natural Sources of $CO_2$ & PM
- Respiration
  - All living things (plants included) release $CO_2$ through respiration
- Decomposition
  - Aerobic Decomposition: Decomposition of organic matter by bacteria & decomposers in the presence of oxygen → releases $CO_2$
  - Anaerobic Decomposition: Decomposition of organic matter by bacteria & decomposers in low or oxygen-free conditions → releases $CH_4$ (methane)
- Natural PM Sources
  - Sea salt, pollen, ash from forest fires & volcanoes dust (windborne soil)
    - Leads to haze (scattering of sunlight & reduced visibility)
PM10 vs. PM2.5
- Particulate Matter: solid or liquid particles suspended in air (also referred to as “particulates).
- PM10 ( <10 micrometers)
 - Particles or droplets like dust, pollen, ash, or mold
 - Too small to be filtered out by nose hairs and trachea cilia; can irritate respiratory tract & cause inflammation
- PM2.5 ( <2.5 micrometers)
 - Particles from combustion (especially vehicles) smaller dust particles
 - More likely to travel deep into the lungs due to smaller size
 - Associated with chronic bronchitis and increased risk of lung cancer

7.5 Indoor Air Pollutants

Learning Objective: STB-2.E: Identify indoor air pollutants.
Essential Knowledge:
- STB-2.E.1: Carbon monoxide is an indoor air pollutant that is classified as an asphyxiant.
- STB-2.E.2: Indoor air pollutants that are classified as particulates include asbestos, dust, and smoke.
- STB-2.E.3: Indoor air pollutants can come from natural sources, human-made sources, and combustion.
- STB-2.E.4: Common natural source indoor air pollutants include radon, mold, and dust.
- STB-2.E.5: Common human-made indoor air pollutants include insulation, Volatile Organic Compounds
- (VOCs) from furniture, paneling and carpets; formaldehyde from building materials, furniture,
- upholstery, and carpeting; and lead from paints.
- STB-2.E.6: Common combustion air pollutants include carbon monoxide, nitrogen oxides, sulfur dioxide, particulates, and tobacco smoke.
- STB-2.E.7: Radon-222 is a naturally occurring radioactive gas that is produced by the decay of uranium found in some rocks and soils.
Essential Knowledge:
- STB-2.F.1: Radon gas can infiltrate homes as it moves up through the soil and enters homes via the basement or cracks in the walls or foundation. It is also dissolved in groundwater that enters homes through a well.
- STB-2.F.2: Exposure to radon gas can lead to radon-induced lung cancer, which is the second leading cause of lung cancer in America.
Developing vs. Developed Countries
- Developing nations use more subsistence fuels such as wood, manure, charcoal (biomass)
  - These biomass fuels release $CO$ , PM, $NO_x$ , VOCs ( can also cause deforestation)
  - Often combusted indoors with poor ventilation, leading to high concentrations
  - Est. 3 billion people globally cook with subsistence fuels, resulting in est. 3.5 - 4.3 million deaths annually
- Developed nations use more commercial fuels (coal, oil, natural gas) supplied by utilities
  - Typically burned in closed, well ventilated furnaces, stoves, etc.
  - Major indoor air pollutants in developed nations come from chemicals in products: adhesives in furniture, cleaning supplies, insulation, lead paint
PM & Asbestos
- Particulates (PM) are a common indoor air pollutant
  - Ex: Smoke (from indoor biomass combustion or cigarettes), dust, and asbestos
- Asbestos is a long, silicate particle previously used in insulation (since been linked to lung cancer & asbestosis)
  - Phased out of use, but still remains in older buildings
  - Not dangerous until insulation is disturbed and asbestos particles enter air & then resp. tract
  - Should be removed by trained professionals with proper respiratory equipment, ventilation in the area it’s being removed from, plastic to seal off area from rest of the building
CO (Carbon Monoxide)
- CO is produced by incomplete combustion of basically any fuel
  - Not all the fuel is combusted due to low $O_2$ or temp.
- CO is an asphyxiant: causes suffocation due to CO binding to hemoglobin in blood, displacing $O_2$
  - Lethal to humans in high concentrations, especially with poor ventilation (odorless and colorless - hard to detect)
- Developed nations: CO released into home by malfunctioning natural gas furnace ventilation
  - Can be detected by carbon monoxide detectors (similar to smoke detectors)
- Developing nations: CO emitted from indoor biomass combustion for heating/cooking
VOCs (Volatile Organic Compounds)
- Chemicals used in variety of home products that easily vaporize, enter air, and irritate eyes, lungs, bronchioles
- Adhesives/sealants: chemicals used to glue carpet down, hold furniture together, seal panels
  - Formaldehyde is a common adhesive in particle board and carpet glues (new carpet smell)
- Cleaners: Common household cleaners and deodorizers such as febreeze
- Plastics and Fabrics: both can release VOCs themselves, or from adhesives used in production
Radon Gas
- Radioactive gas released by decay of uranium naturally found in rocks underground (granite especially)
  - Usually enters homes through cracks in the foundation & then disperses up from basement/foundation through home
  - Can also seep into groundwater sources & enter body through drinking water
  - 2nd leading cause of lung cancer after smoking
  - EPA recommends testing homes with airborne Radon monitor
  - Sealing cracks in foundation can prevent it from entering and increasing ventilation in the home can disperse it if it’s detected
Dust & Mold
- Natural indoor air pollutants that can worsen asthma, bronchitis, COPD, emphysema
  - Dust settles in homes naturally, is disturbed by movement, entering air and then respiratory tract
  - Mold develops in areas that are dark and damp and aren’t well ventilated (under sinks/showers, behind panels in walls and ceiling)
  - Black mold is a class of mold that releases spores into air
    - Especially harmful to resp. system
  - Can be removed by physically cleaning mold out and fixing the water leak or ventilation issue that lead to mold forming
Lead
- Found in paint in old homes (EPA banned lead paint in 78’)
- Paint chips off walls/windows and is eaten by small children (due to curiosity & sweet taste) or inhaled as dust
- Lead water pipes can also release lead into drinking water sources (as in Flint) but it’s less common than lead paint
- Damages central nervous system of children due to smaller size and still developing brain
- Can be removed from home by stripping lead paint and replacing with non-lead based paint
- Lead water pipes can be replaced by cities with copper pipes

7.6 - Reduction of Air Pollutants

Learning Objective: STB-2.G: Explain how air pollutants can be reduced at the source.
Essential Knowledge:
- STB-2.G.1: Methods to reduce air pollutants include regulatory practices, conservation practices, and alternative fuels.
- STB-2.G.2: A vapor recovery nozzle is an air pollution control device on a gasoline pump that prevents fumes from escaping into the atmosphere when fueling a motor vehicle.
- STB-2.G.3: A catalytic converter is an air pollution control device for internal combustion engines that converts pollutants ( $CO$ , $NOx$ , and hydrocarbons) in exhaust into less harmful molecules ( $CO2$ , $N2$ , $O2$ , and $H_2O$ ).
- STB-2.G.4: Wet and dry scrubbers are air pollution control devices that remove particulates and/or gases from industrial exhaust streams.
- STB-2.G.5: Methods to reduce air pollution from coal-burning power plants include scrubbers and electrostatic precipitators.
Reducing Emissions = reducing air pollutants
- Drive less, walk/bike/bus more
- Conserve electricity (smart appliances)
- Eat more plants, less meat
- Renewable, non-pollution emitting energy (solar, wind, hydro)
Laws/Regulations
- Clean Air Act
 - Allows EPA to set acceptable levels for criteria air pollutants
 - Monitor emissions levels from power plants and other facilities
 - Tax/sue/fine corporations that release emissions above levels
- CAFE Vehicle Standards
 - (Corporate Average Fuel Economy) standards require the entire US “fleet” of vehicles to meet certain average fuel
 - Requires vehicle manufacturers to work to make more efficient vehicles
 - More efficient vehicles burn less gasoline and release less $NOx$ , PM, $CO$ , and $CO2$
- Pollution Credits
 - Similar to ITQs for fish
 - Companies that reduce emissions well below EPA-set levels earn pollution credits
 - They can sell these to companies that release more than acceptable levels
Reducing Vehicle Air Pollutants
- Vapor Recovery Nozzle
 - Capture hydrocarbon VOCs released from gasoline fumes during refueling
 - Separate tube inside nozzle captures vapors & returns them to underground storage tank beneath the gas station
 - Reduces VOCs, which contribute to smog & irritate resp. tracts
 - Also reduces benzene (carcinogen) released from gasoline vapors
- Catalytic Converter (CC)
 - Required on all vehicles after 1975
 - Contains metals (platinum & palladium) that bind to $NO_x$ and $CO$
 - CC converts $NOx$ , $CO$ , and other hydrocarbons into $CO2$ , $N2$ , $O2$ , and $H_2O$
Reducing $SOx$ & $NOx$
- Crushed Limestone ( $SO_2$ )
 - Used to reduce $SO_2$ from coal power plants
 - Crushed coal mixed with limestone (calcium carbonate) before being burned in boiler
 - Calcium carbonate in limestone combines with $SO2$ to produce calcium sulfate, reducing the $SO2$ being emitted
 - Calcium sulfate can be used to make gypsum wallboard or sheetrock for home foundations
- Fluidized Bed Combustion ( $NO_x$ )
 - 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
 - Also allows coal to be combusted at lower temp, which emits less $NO_x$
Wet & Dry Scrubbers
- Dry Scrubbers ( $NOx$ , $SOx$ , VOCs)
 - Large column/tube/pipe filled with chemicals that absorb or neutralize oxides ( $NOx$ , $SOx$ , VOCs) from exhaust streams (emissions)
 - Calcium oxide is a common dry scrubber additive which reacts with $SO_2$ to form calcium sulfite
- Wet Scrubbers ( $NOx$ , $SOx$ , VOCs + PM)
 - May involve chemical agents that absorb or neutralize $NOx$ , $SOx$ , VOCs, but also include mist nozzles that trap PM in water droplets as well
 - Mist droplets with pollutants and PM trapped in them fall to bottom of scrubber or get trapped @ top by mist eliminator
 - Sludge collection system traps polluted water for disposal
Reducing PM
- Electrostatic Precipitator
  - Power plant/factory emissions passed through device with a neg. charged electrode, giving particles a neg. Charge
  - Neg. charged particles stick to pos. charged collection plates, trapping them
  - Plates discharged occasionally so particles fall down into collection hopper for disposal in landfills
- Baghouse Filter (PM)
  - Large fabric bag filters that trap PM as air from combustion/industrial process passes through
  - Shaker device knocks trapped particles loose into collection hopper below
  - PM collected & taken to landfill

7.7 Acid Rain

Learning Objective:
- STB-2.H: Describe acid deposition.
Essential Knowledge:
- STB-2.H.1: Acid rain and deposition is due to nitrogen oxides and sulfur oxides from anthropogenic and natural sources in the atmosphere.
- STB-2.H.2: Nitric oxides that cause acid deposition come from motor vehicles and coal-burning power plants. Sulfur dioxides that cause acid deposition come from coal-burning power plants.
Learning Objective:
- STB-2.I: Describe the effects of acid deposition on the environment.
Essential Knowledge:
- STB-2.I.1: Acid deposition mainly affects communities that are downwind from coal-burning power plants.
- STB-2.I.2: Acid rain and deposition can lead to the acidification of soils and bodies of water and corrosion of human-made structures.
- STB-2.I.3: Regional differences in soils and bedrock affect the impact that acid deposition has on the region-such as limestone bedrock's ability to neutralize the effect of acid rain on lakes and ponds.
Major Sources
- Sources of $NOx$ & $SO2$
 - $SO_2$ - Coal fired power plants, metal factories, vehicles that burn diesel fuel
 - $NO_x$ - vehicle emissions, diesel generators coal power plants
- $NOx$ and $SO2$ are the primary pollutants that cause most acid precipitation
 - Reducing $NOx$ & $SO2$ emissions reduces acid deposition
 - Higher CAFE Standards
 - More public transit
 - Renewable energy sources
 - More efficient electricity use
 - Since passage of Clean Air Act, acid deposition has decreased significantly
Acid Formation
- $NOx$ and $SO2$ react with $O2$ and $H2O$ in the atmosphere, forming nitric and sulfuric acid
 - Sulfuric acid and nitric acid dissociate in the presence of water into sulfate and nitrate ions, and hydrogen ions ( $H^+$ )
 - Acidic rain water (higher $H^+$ conc.) deceases soil and water pH; can limit tree growth in forests down wind from major $SO2$ & $NOx$ sources
Env. Effects of Acid Rain
- Soil/Water Acidification
  - $H^+$ ions displace or leech other pos. charged nutrients ( $Ca^{2+}$ , $K^+$ ) from soil
  - $H^+$ ions also make toxic metals like aluminum and mercury more soluble in soil and water
    - This can slow growth or kill plants and animals living in the soil or water
  - Acidity = higher $H^+$ ion concentration, lower pH
Env. Effects of Acid Rain
- pH Tolerance
 - Aquatic species have diff. pH tolerances
 - As pH decreases (more acidic) outside optimal range for a species, pop. declines
 - When pH leaves range of tolerance, they cannot survive at all, due to:
 - Aluminum toxicity
 - Disrupted blood osmolarity ( $Na^+/Cl^-$ balance disrupted at low pH)
 - Indicator species can be surveyed and used to determine conditions of an ecosystem (soil, water, etc.)
 - Ex: high whitemoss/filamentous algae pop. indicates pH < 6.0
 - High crustacean pop. indicates pH > 6.0
Mitigating Acid Rain
- Limestone
 - Calcium carbonate ( $CaCO3$ ) reacts with $H^+$ ions, forming $HCO3$ and giving off $Ca^{2+}$
 - This “neutralizes” acidic water/soil, moving it closer to a pH of 7
 - Limestone (calcium carbonate) is a natural base that can neutralize acidic soil/water
 - Regions with limestone bedrock have some natural buffering of acid rain
 - Humans can also add crushed limestone to soils/waters to neutralize
- Limiting $SO2$ & $NOx$
 - Decreasing these primary pollutants that drive acid rain can reduce it
 - Renewable energy sources, decreasing coal comb.
 - Fluidized bed combustion & lower burning temp. for existing coal power plants
 - Dry or wet scrubbers
 - Acid rain can corrode human structures, especially those made from limestone

7.8 Noise Pollution

Learning Objective: STB-2.J: Describe human activities that result in noise pollution and its effects.
Essential Knowledge:
- STB-2.J.1: Noise pollution is sound at levels high enough to cause physiological stress and hearing loss.
- STB-2.J.2: Sources of noise pollution in urban areas include transportation, construction, and domestic and industrial activity.
- STB-2.J.3: Some effects of noise pollution on animals in ecological systems include stress, the masking of sounds used to communicate or hunt, damaged hearing, and causing changes to migratory routes.
Urban Noise Pollution
- Construction: jack hammers, trucks, concrete pouring
- Transportation: cars, busses, trains
- Industrial activity: manufacturing plants
- Domestic activity: neighbor’s music, lawn mowing, home projects
- Any noise at great enough volume to cause physiological stress (difficulty communicating, headaches, confusion) or hearing loss
Wildlife Effects (land)
- Noise pollution can disrupt animal communication, migration, and damage hearing
  - Physiological stress: caterpillar hearts beat faster when exposed to simulated highway noise pollution
    - Could drive pollinator species decline
  - Hearing: can prevent predators from hearing prey and vice versa; can prevent mates from locating each other (both of these decrease chances of survival)
Wildlife Effects (Aquatic)
- Aquatic noise pollution comes from the noise of ship engines, military sonar, and seismic air blasts from oil & gas surveying ships
  - Physiological stress: hearing loss, disrupted communication, mating calls, predator and prey navigation
  - Whales are especially prone to having migration routes disrupted as their vocal communication is disrupted
  - Seismic surveying ships send huge air blasts down into the water, searching for oil by recording how the echo is returned from ocean floor
    - So loud that researchers off the coast of Virginia can detect blasts from coast of Brazil

Air Pollution Notes

7.1 Introduction to Air Pollution (Pollutants)

7.2 Photochemical Smog

7.3 Thermal Inversion

7.4 Atmospheric CO2CO_2CO2​ & PM

7.5 Indoor Air Pollutants

7.6 - Reduction of Air Pollutants

7.7 Acid Rain

7.8 Noise Pollution

7.4 Atmospheric $CO_2$ & PM