Air Lecture Notes.docx

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Western University
Environmental Science
Environmental Science 1021F/G
Geoff Stewart

Air Lecture Notes Troposphere  Air we breathe  Note level of CO2 (0.038%) is small but not insignificant. This low amount is required to keep balance in Earth's climate & health of  Greenhouse gases - required to maintain health of Earth, but can be harmful if in abundance  VOCs = volatile organic compounds o Synthetic harmful chemicals in everyday products (paint, carpet, upholstery, cosmetics)  NO(x) - nitrous oxide Outdoor Air Pollution  Air pollutant = chemical that at high concentration causes damage  Air pollutants: Small particulate matter, SO2, ozone, lead  Natural sources of pollutants: fire, dust, salty sea spray (vaporized salt can be a pollutant) o Although they're natural, they can still harm  Mobile sources: shipping vessel, plane, train, car, anything that pollutes and moves around  Stationary sources: factories,  Primary pollutants: chemicals that come directly from source of pollutants (factory vent, exhaust pipe, volcano)  Secondary pollutant: chemicals formed from chemical rxns among primary pollutants  Why should CO2 be considered an air pollutant? o It's at unnaturally high concentrations o It's causing problems Results of climate change resulting from chemical pollutants: Change in precipitation patterns  o Where/when it falls  Change in ability to grow in fertile soils that get more or less rain than previously  Rising sea levels o Water melting from glaciers, snow caps Organic in chemical sense = chemical compounds contain Photochemical smog hydrogen, oxygen, and carbon  Combination of air pollutants, NOx, heat, and sunlight  Creates bad ozone  Erodes solid structures, irritates eyes & breathing (esp. felt by asthmatics)  Increased by global warming  Plants that produce VOCs: sycamore, poplar, oak, and Kudzu vine (invasive species in SW ON) Industrial Smog  Sulphur dioxide (SO2), drops of slupheric acid, and suspended particles o No NOx  Caused by burnin coal & oil  Gray in colour Reducing Smog:  Reducing activities that create smog  Precipitation o Then pollutants go into water system  Wind o Disperses pollutants so they can't react w/ each other o Doesn't get rid of problem, but dilutes it o Therefore tall buildings, hills, and mountains block wind and prevent pollutants from dispersing (valleys naturally have more smog) Increasing Smog  Grasshopper effect o Taller smokestacks are built intended to prevent pollutants from falling on city - prevents smog in that area o Pollutants just gather elsewhere, this doesn't fix the problem  Cities hold in heat (heat islands) Air Pollution from Acid Deposition  Acid deposition o wet: precipitation contaminated w/ sulphuric acid  Usually falls away from source, because it needs to gather in clouds, combine w/ water  Can cause leaching by breaking down toxic metals (eg. Lead) and carrying that to water source o dry: compounds that fall to ground near source  Fish particularly sensitive to acid o Changes chemistry in body of water, makes water more acidic o Fish suffocate o Particularly issue in spring when acid snow melts and goes directly to bodies of water where fish live  Plants can't survive acidic soils o Decreases immune function o Nutrients leach, calcium deficiency o Burns the plants o Less able to photosynthesize - become yellow because less chlorophyll  Acid-loving plants thrive, changing plant community  Reduce soil buffering capacity - soils less able to withstand harm from pH fluctuations - will become acidic Solutions to Acid Deposition  Neutralizing chemicals added to water & soil Lecture Part 2 Terminology: Global warming = average temperature increase on land, water, air Global climate change = changes in aspects of Earth's climate  Warmer or cooler  More/less precipitation  Wind force & direction Global air circulation is affected by  Uneven heating of Earth - equator to north/south hemispheres & seasonally  Created basically by rising warm air, falling cool air o Cold air cell falls, warmed by Earth, picks up  Air cell patterns o Moist at equator o Deserts at 30 N & 30 S o Temperate forests 60 N & 60 S  Rotation of Earth on axis (Coriolis effect) o Earth appears to be moving faster at equator because circumference is bigger o Air is pushed West from Northeast & Southeast at equator o Deflection winds: N hemisphere winds go West to East, S hemisphere winds go East to West Historical Climate Change  Global temperature o Earth always in periods of rising & cooling o Last major glacial period 12 tya (relatively stable since - helped human development into agricultural revolution, green revolution) o We are currently on an increase in temperature, beginning within last 100 years  Air composition (various greenhouse gases, etc.)  Sea levels  Glacial procession & recession Studying Change  Ice cores o Preserved precipitation from last hundreds of years o Air bubbles analysed for Concentration of Greenhouse gasses, others on slide   Sediment cores o Former species present  Pollen, seeds, fossils  A species found here similar to rainforest species - we can conclude we likely had a much warmer climate tya  Conclusions: from ice core samples, although CO2 levels have fluctuated, they've never been above 300 ppm. We're at 381.9, this increase post-industrial revolution Cause of up & down in CO2 l
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