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
