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14- 1. Housekeeping Items. Any comments on Scott’s talk on the Salish Sea? His slides are up on the web site and, if you are interested in more information, let me know and I will print off some handouts he brought.
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Housekeeping Items • Any comments on Scott’s talk on the Salish Sea? His slides are up on the web site and, if you are interested in more information, let me know and I will print off some handouts he brought. • As you know, the class e-mail messages have not been working consistently. Did you get the one about the Global Issues Film Festival and, if so, did anyone go? • On Tuesday at 7, the film “Salmon Confidential” will be showing in Building 200, Room 203. • I’m still working my way through the outdoor exercises, but they should be done by Wednesday. • Today we’re going to focus on atmospheric science and air pollution, though we will skip over the material usually covered in GEOG 211: Atmospheric Environments.
Describe the composition, structure, and function of Earth’s atmosphere Outline the scope of outdoor air pollution andassess potential solutions Explain stratospheric ozone depletion and identify steps taken to address it Define acidic deposition and illustrate its consequences Characterize the scope of indoor air pollution and assess potential solutions Upon successfully completing this chapter, you will be able to
Central Case: The Rain and the big Nickel “Despite Canada’s success at reducing acid-causing emissions, acid deposition is still affecting our environment.” – Environment Canada • Mining and refining in Sudbury, Ontario generates high SO2 emissions, leading to acid rain • 1972: Built a 380m superstack to disperse emissions • 1980s: cleaned emissions prior to releasing them • Acidification and remediation studied at the Experimental Lakes Area in northwestern Ontario • Better ecological awareness today
The atmosphere and weather • Atmosphere = the thin layer of gases that surrounds Earth • Absorbs radiation and moderates climate • Transports and recycles water and nutrients • 78% nitrogen gas, 21% oxygen gas, 1% other gases • Its four layers differ in temperature, density and composition • Minute concentrations of permanent (remain at stable concentrations) and variable gases (varying concentrations) • Human activity is changing the amounts of some gases
The atmosphere is layered • Troposphere = bottommost layer • Air for breathing, weather • Temperature declines with altitude • Tropopause = limits mixing between troposphere and the layer above it • Stratosphere = 11-50 km (7-31 mi) above sea level • Drier and less dense, with little vertical mixing • Colder in its lower regions • Contains UV radiation-blocking ozone, 17-30 km (10-19 mi) above sea level
The atmosphere is layered (cont’d) • Mesosphere = 50-80 km (31-56 mi) above sea level • Extremely low air pressure • Temperatures decrease with altitude • Thermosphere = atmosphere’s top layer • Extends upward to 500 m (300 mi)
Atmospheric properties include temperature, pressure, and humidity • Atmospheric pressure = measures the force per unit area produced by a column of air • Relative humidity = the ratio of water vapor a given volume of air contains to the amount it could contain at a given temperature • Microclimate = different weather pattern on side of hill sheltered from wind or direct sunlight
Solar energy heats the atmosphere, helps create seasons, and causes air to circulate • The spatial relationship between the Earth and sun determines the amount of solar energy striking the Earth • Energy from the sun • Heats air • Moves air • Creates seasons • Influences weather and climate • Solar radiation is highest near the equator
Solar energy heats the atmosphere, helps create seasons, and causes air to circulate (cont’d) • Earth is titled on its axis by about 23.5% • Northern and Southern Hemispheres each tilt toward the sun for half the year • Results in change of seasons • Regions near equator largely unaffected • Near poles the effect is strong
Solar energy heats the atmosphere, helps create seasons, and causes air to circulate (cont’d) • Convective circulation = less dense, warmer air rises and creates vertical currents • Rising air expands and cools • Cool air descends and becomes denser, replacing warm air • Influences both weather and climate
The atmosphere drives weather and climate • Weather = specifies atmospheric conditions over short time periods and within a small geographic areas • Climate = describes patterns of atmospheric conditions across large geographic regions over long periods of time “Climate is what we expect; weather is what we get.” - Mark Twain
Front = the boundary between air masses that differ in temperature, moisture, and density Air masses interact to produce weather • Warm Front = the boundary where warm moist air replaces colder, drier air • Cold Front = the boundary where colder, drier air displaces warmer, moister air
Air masses interact to produce weather (cont’d) • High-pressure system = air that moves away from a center of high pressure as it descends • Brings fair weather • Low-pressure system = air moves toward the low atmospheric pressure at the center of the system and spirals upward • Clouds and precipitation
Air masses interact to produce weather (cont’d) • Normally there is vertical mixing • Thermal inversion = a layer of cool air occurs beneath a layer of warmer air • Inversion layer = the band of air in which temperature rises with altitude • Denser, cooler air at the bottom of the layer resists mixing
Large-scale circulation systems produce global climate patterns • Hadley cells =a pair of convective air currents near the equator wheresurface air warms, rises, and expands • Ferrel cells and polar cells = convective cells that lift air and create precipitation at 60 degrees latitude north and south • These interact with Earth’s rotation to produce global wind patterns • Coriolis effect = the north-south air currents of the convective cells appear to be deflected from a straight path
Large-scale circulation systems produce global climate patterns (cont’d) • Doldrums = near the equator • Few winds • Trade winds = between the equator and 30 degrees latitude • Blow from east to west • Westerlies = from 30 to 60 degrees latitude • Originate from the west and blow east
Outdoor Air Pollution 14-25
Outdoor air pollution • Air pollutants = gases and particulate material added to the atmosphere • Can affect climate or harm people • Air pollution = the release of pollutants • Outdoor (ambient) air pollution = pollution outside • Has recently decreased due to government policy and improved technologies in developed countries • Developing countries and urban areas still have significant problems
Natural sources can pollute • Dust storms = Hundreds of millions of tons of dust are blown westward across the Atlantic Ocean by trade winds every year • From Africa to the Americas • Unsustainable farming and grazing, erosion and desertification
Natural sources can pollute (cont’d) • Volcaniceruptions = release large quantities of particulate matter, sulfur dioxide & other gases • Can remain for months or years • Aerosols = reflect sunlight back into space and cool the atmosphere and surface • Sulphur dioxide
Natural sources can pollute (cont’d) • Burning vegetation = pollutes atmosphere with soot and gases • Over 60 million hectares of forests and grasslands burn per year • Fires are made more severe by human action • Decades of fire suppression • Fires from “slash-and-burn” clearing of forests
We create various types of outdoor air pollution • Point Sources = specific spots where large quantities of pollutants are discharged (power plants and factories) • Nonpoint Sources = more diffuse, consisting of many small sources (automobiles) • Primary Pollutants = directly harmful and can react to form harmful substances (soot and carbon dioxide) • Secondary Pollutants = form when primary pollutants interact or react with constituents or components of the atmosphere (tropospheric ozone and sulfuric acid)
CEPA identifies harmful airborne substances • 1999: Canadian Environmental Protection Act • Environment Canada groups pollutants of greatest concern into four categories: • Criteria air contaminants • Persistent organic pollutants • Heavy metals • Toxic air pollutants
CEPA identifies harmful airborne substances (cont’d) • Criteria air contaminants = pollutants judged to pose especially great threats to human health, produced by a number of processes (burning of fossil fuels) • Sulphur dioxide (SO2) • Nitrogen dioxide (NO2) • Particulate matter (PM) • Volatile organic compound (VOC or VOX) • Carbon monoxide (CO) • Ammonia (NH3) • Tropospheric ozone (O3)
Bad Air Days weighingtheissues Are you sensitive to smog? Do you suffer from itchy eyes, burning lungs, or other symptoms on “bad air days”? Do you think there is a smog problem in your area? • If you visit the website of the National Air Pollution Surveillance Network (NAPS), maintained by Environment Canada, you can watch animations of severe smog events in which ground-level ozone exceeded the accepted air quality standard levels over very large areas of both Canada and the United States (www.etc-te.ec.gc.ca/NAPS/naps_smog_e.html).
CEPA identifies harmful airborne substances (cont’d) • Persistent organic pollutants = can last in the environment for long periods of time, they are volatile (evaporate readily) • They can enter food supply • Bioaccumulate in body tissues • Significant impact on human health and environment • Come primary from human activity • Examples include industrial chemicals • PCBs • DDT • Contaminants from incomplete combustion processes
A Current Controversy Involves Incinerators • In Europe, Energy From Waste incinerators are operated with virtually zero pollution, but in North America they inspire mortal fear. Metro Vancouver wants to build one at Duke Point. Earlier it wanted to build one that would send emissions down the Fraser Valley, and this was vigourously opposed.
CEPA identifies harmful airborne substances (cont’d) • Heavy metals = can be transported by air, water, and food supply, and can reside in the sediment for long periods of time • Poisonous even in low concentrations • Accumulate in body tissues • Carried long distances from source • Mercury and lead
CEPA identifies harmful airborne substances (cont’d) • Toxic air pollutants = broad category of “other” pollutants as being harmful or toxic • Cause cancer • Cause developmental or neurological problems in various body systems. • Overlaps with other types of air pollutants (lead, ozone) • Most are produced by human activities (smelting, sewage treatment, industrial processes)
Investigating Your Region’s Air Quality weighingtheissues How polluted is the air near where you live? Go to the National Pollutant Release Inventory (NPRI) website at www.ec.gc.ca/pdb/npri/npri_home_e.cfm. Use the Google Earth mapping tool to check on the amounts of pollutants released in your own province or local area. • Are there any specific facilities in your area that are major emitters of atmospheric pollutants?