Unit 3- Air Pollution Flashcards
Atmosphere:
• Thin layer of gases that surrounds Earth
• Permanent gases- remain at stable concentrations
• Variable gases- Vary in concentration from time or place to place as a result of natural processes or human activities
Emergence of autotrophic microbes that emit oxygen as a by product of photosynthesis caused oxygen to build up in an atmosphere that was mainly CO2, N, CO, and H2
Troposphere Stratosphere Ozone Layer Mesosphere Thermosphere
Troposphere
○ Bottommost layer
○ Provides air we need to survive
○ Movement of air within troposphere is largely responsible for the planet’s weather
○ Thin (11 km) compared to other layers, but contains 3/4 of the atmosphere’s mass because air is denser near Earth’s surface
○ Tropospheric air temperature declines by 6 degrees C for each km in altitude, reaching -52 degrees at its highest point
Tropopause
§ Altitude at which temperatures stop declining with altitude
Acts like a cap, limiting mixing between the troposphere and the stratosphere
Stratosphere
○ Similar in composition to troposphere, but is 1000 times as dry and less dense
○ Gases experience little vertical mixing, so once substances and pollutants enter it, they remain there for a long time
Maximum temperature of -3 degrees at its higher altitude, but is older lower down because ozone and oxygen absorb and scatter UV radiation so the upper stratosphere is warmer
Ozone Layer
○ Greatly reduces the amount of UV radiation that reaches the Earth’s surface
UV radiation damages living tissue and induces mutations in DNA, ozone layer provides protection
Mesosphere
○ Air pressure is extremely low
Temperatures decrease with altitude, reaching lowest point at the top of the mesosphere
Thermosphere
○ Top layer
Extends to 500 km above sea level
Weather
Atmospheric conditions over short time periods in small geographic areas
Climate
Pattern of atmospheric conditions found across large geographic regions over long periods
Canadian Environmental Protection Act (CEPA) and Air Pollutants:
• Groups pollutants of great concern into 4 categories ○ Criteria air contaminants (CACs) ○ Persistent organic pollutants ○ Heavy metals Toxic air pollutants
Criteria Air Contaminants (CACs):
• Produced in varying quantities by a number of processing (i.e. burning of fossil fuels)
First to come under government regulation due to impact on human health
Sulphur Dioxide Nitrogen Dioxide Particulate matter Volatile Organic Compounds Carbon Monoxide Ammonia Tropospheric Ozone
Sulphur Dioxide
○ Colourless gas with a strong odour
○ Results from combustion of coal for electricity generation and industry
Can react to form sulphuric acid, which can fall as acid rain
Nitrogen Dioxide
○ Highly reactive, foul smelling, reddish brown gas
○ Contributes to smog and acid rain
○ Along with nitric oxide, nitrogen dioxide belongs to a family of nitrogen oxides
Result when atmospheric nitrogen and oxygen react at high temperature created by combustion engines (i.e. cars, coal…etc)
Particulate Matter (PM)
○ Solid or liquid particles small enough to be suspended in the atmosphere
○ Also called suspended particulates (SP)
○ Includes primary pollutants like dust and soot, as well as secondary pollutants like sulphates and nitrates
○ Can damage respiratory tissues when inhaled
Released mainly from coal combustion
Volatile Organic Compounds (VOCs or VOX)
○ Carbon containing chemicals used in and emitted by vehicle engines and a variety of solvents and industrial processes, as well as many household chemicals
○ i.e. methane, propane
Most comes from human activity
Carbon Monoxide
○ Colourless odourless gas produced by incomplete combustion of fuel
○ Vehicles are the main source
Binds to hemoglobin in red blood cells, preventing them from carrying oxygen
Ammonia
○ Colourless gas with a strong odour
○ Generated from livestock waste and fertilizer production
○ Poisonous if inhaled in great quantities
In the atmosphere, combines with sulphates and nitrates to form secondary fine particulate matter
Tropospheric Ozone
○ Ground level ozone (not ozone in the stratosphere)
○ Forms and accumulates at ground level
○ Results from interaction of sunlight, heat, nitrogen oxides, and carbon containing chemicals
○ Secondary pollutant
Instable, can release a free oxygen atom that can react to damage tissues
Persistent Organic Pollutants (POPs):
• Can last in environment for a long time
• Volatile, can travel great distances in the air
• Remain in environmental reservoirs for a long time, take a long time to degrade
• Can enter food supply and impact human health in low quantities
Come from industrial chemicals
Heavy Metals:
- Can be transported by ait, enter food and water supply, and reside for long periods in sediments
- Occur in particulate matter form, or attach to small particles that can be transported atmospherically
- Poisonous even in low concentrations
- Long range transport of atmospheric pollutants (LRTAP) carry pollutants across continents through atmospheric currents and deposit them on land and water surfaces
- i.e. lead, mercury
Toxic Air Pollutants:
• Category of “other” pollutants identified as being harmful or toxic
○ i.e. cancer causing, reproductive defects…etc
• Overlaps with other types of air pollutants
i.e. Lead is a air pollutants, but also appears in other categories
Smog:
• Most common, widespread air quality problem
• Unhealthy mixtures of air pollutants that often form over urban areas
Industrial smog- grey air smog formed by CO and soot when coal and oil is partially combusted, also contains sulphur dioxide
Airshed
Geographic area associated with a particular air mass
○ People who live within the same airshed experience similar weather
Airsheds are topographically constrained
