1 / 58

The Atmosphere

The Atmosphere. Composition. Nitrogen (~78%) Oxygen (~21%) Argon (~0.93%) Carbon dioxide (~0.039%) Rest is made of trace gases Water vapor (~1%). Density and Pressure. Sea level is the densest region Atmospheric pressure is the measure of mass per unit of air

kaitlin-dennis
Download Presentation

The Atmosphere

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The Atmosphere

  2. Composition • Nitrogen (~78%) • Oxygen (~21%) • Argon (~0.93%) • Carbon dioxide (~0.039%) • Rest is made of trace gases • Water vapor (~1%)

  3. Density and Pressure • Sea level is the densest region • Atmospheric pressure is the measure of mass per unit of air • Decreases as altitude increases

  4. Basic Layers • Thermosphere • Mesosphere • Stratosphere • Troposphere

  5. Troposphere • 75-80% of all air in the atmosphere • Extends up about 11 mi @ equator & 5 mi @ poles • Where all the weather is • We live here

  6. Stratosphere • Extends from top of troposphere to about 30 mi above the Earth • Less matter, less water vapor, and way more ozone (O3) • Where the “ozone hole” is

  7. Stratospheric Ozone • Forms when O2 interacts with UV radiation • Blocks about 95% of harmful radiation • Prevents oxygen in the troposphere from becoming ozone

  8. Ozone Hole • First really noticed/ studied in 1970’s • Over the Antarctic and Australia • Seems to be cyclical (gets bigger then shrinks) • Caused almost entirely by human-made CFCs (no natural source of CFCs)

  9. Air Pollution • Presence of chemicals in the atmosphere in high enough concentrations to affect both organisms and climate • Effects can range from a minor irritant or cause of death

  10. Natural Sources of Air Pollution • Volcanoes • Decaying plants • Forest fires • Sea spray • Dust storms

  11. Air Pollutants • Natural • Stationary • Mobile

  12. Sources of pollution in –ED countries • Transportation (mostly cars and trucks) • Electric power plants that burn coal or oil • Industry (especially steel mills, metal smelters, oil refineries, and pulp/paper mills)

  13. Primary v Secondary Sources • Primary pollutants are emitted directly into the atmosphere and are potentially harmful • Soot and carbon dioxide • Secondary pollutants are primary pollutants that have reacted in the air and changed into a new form

  14. Criteria Air Pollutants • Most common air pollutants • EPA is required to collect scientific and medical information on their effects • National Ambient Air Quality Standards (NAAQS- known as “nax”) specify the maximum levels of concentration of these pollutants allowable in outside air.

  15. CAP #1 Particulates • All airborne pollutants either liquid or solid • Includes pollen, dust, soot, smoke, acid condensates, etc • Range in size from fly ash (thumbnail) to tiny aerosols (less than 1 µm)

  16. CAP #1 Particulates Sources • Combustion • Forest fires • Industrial processes • Vehicle exhaust Effects • Can cause respiratory disease  depends on: • Size of the particle • Chemical nature  Air Pollution over China!

  17. CAP #2 Sulfur Dioxide (SO2) Sources • Mainly from burning coal • Metal smelters • Industrial boilers • Oil refineries Effects • Reacts with water to form sulfuric acid  Acid Rain • Contributes to respiratory illness & aggravates existing heart and lung diseases

  18. Sources

  19. CAP #3 Carbon Monoxide • Odorless, colorless, poisonous Sources • Incomplete combustion from cars and industry Effects • CO has a greater affinity for hemoglobin that oxygen headaches, drowsiness, and death

  20. CAP #3 Carbon Monoxide (CO) • CO is a product of incomplete combustion: Ex: C8H18 + O2 CO + H20 + hydrocarbons (not enough O2  incomplete combustion) Ex: C8H18 + O2 CO + H20 (lots of O2  complete combustion) Amount of incomplete combustion is reduced by a catalytic converter

  21. CAP #4 Nitrogen Oxides (NOx) • Nitrogen oxides are formed when combustion occurs at very high temperatures Sources • Burning fuels in vehicles & power plants Effects • Precursor of ozone/ smog • Reacts with water to form nitric acid  acid rain • Contributes to eutrophication • Aggravates respiratory diseases

  22. CAP #5 Lead • Excessive exposure to lead may cause neurological impairments such as seizures, mental retardation, & behavioral disorders. • Even at low doses, lead exposure is associated with damage to the nervous systems of fetuses &young children, resulting in learning deficits & lowered IQ

  23. Leaded gasoline • Many countries in Northern Africa, the Middle East, and former Soviet nations still use leaded gasoline • The US banned leaded gasoline in 1995 (CA in ‘92) • NASCAR still used it until 2005…

  24. CAP #6 Ground Level Ozone • Ozone, NO2, and PANs are the main constituents of photochemical smog NOx + VOCs + sunlight  ozone + PANs + hydrocarbons • VOCs= volatile organic compounds from fuels, paints, & glues • PANs= Peroxyacetylnitrate

  25. CAP #6 Ground Level Ozone • VOCs, NOx, & sunlight are needed for ozone • The hotter the day, the higher the levels of ozone and other photochemical oxidants • Ozone “season”: May 1- Sept 30

  26. CAP #6 Ground Level Ozone • Exposure causes decreased lung function, inflammation of the airways, & aggravates lung diseases such as asthma • Ozone also affects vegetation & ecosystems, leading to reductions in agricultural crop & commercial forest yields, reduced growth & survivability of tree seedlings, & increased plant susceptibility to disease, pests, & other environmental stresses (ex: harsh weather)

  27. Photochemical Smog • Forms when a mixture of NOx & volatile organic hydrocarbon compounds react with sunlight to create 100+ secondary pollutants

  28. Trees = Smog? • Some tree species (some oaks, sweet gums, poplars, and kudzu) emit VOCs • Only a factor if a forest is near a major city

  29. Formation of Smog

  30. Industrial Smog • Made of sulfur dioxide, sulfuric acid, & suspended particulates • Created when coal & oil are burned • Primarily a problem in the late 19th/ early 20th century (London smog) & developing countries

  31. Atmospheric Inversions • Atmospheric inversion: cool air (heavier than warm air) is unable to rise and mix and remain stable • Where and when are thermal inversions likely to occur?

  32. Atmospheric Inversions • Form in a town/ city that is located in a valley surrounded by mountains & gets cold, cloudy weather for part of the year • Donora, PA • Form in a large metropolis w a sunny climate, light winds, mountains on 3 sides, & an ocean coast • Los Angeles, CA

  33. Factors that increase OAP • Urban buildings • Hills & mountains • High temperatures (more smog in hot climates) • Grasshopper effect (send pollutants to poles) • How might this effect polar critters?

  34. Factors that decrease OAP • Rain & snow (dry cities have more photochemical smog) • Salty sea spray from the ocean • Wind (takes away polluted air & brings in fresh air) • Why might this also be a negative?

  35. Acid Deposition • Pollutants expelled from smokestacks from power plants & factories travel on the wind to other areas (as far away as 600 mi!) and can cause regional air pollution • During their trip, secondary pollutants form

  36. Acid Deposition • Wet deposition is acidic precipitation, snow, fog, and cloud vapor with a pH of less than 5.6 • Dry deposition is dry acidic particles that fall from the sky • Within 2-3 days, pretty close to emission source

  37. Acid Rain • Generally, rain water has a pH value of 5.6 because of the carbon dioxide from air dissolved in it • Any rainfall has a pH value less than 5.6 is defined as acid rain • Some regions have rain with a pH as low as 2.3! (1000x normal acidity!!!)

  38. Vulnerability to Acid Rain • An ecosystem’s sensitivity to acid preparation is determined by the chemical composition of its soil and bedrock (buffering capacity ability to neutralize acids) • Low buffering capacity  naturally acidic soil and/or granite rock • High buffering capacity  alkaline soils and/or limestone bedrock • Over time, soil’s buffering capacity can be overwhelmed by acidic inputs

  39. Effect on Aquatic Ecosystems • Most freshwater organisms do best in waters that are slightly alkaline (pH=8) • Fish population decline is largely due to acid induced reproductive failure • Acid shock often follows spring snow melt (also a critical developmental period for many larvae) • Acidified lakes appear extremely clear

  40. Acid Deposition & Heavy Metals • As pH decreases, toxic metals (Al, Mn, Pb, Zn, Hg, & Cd) dissolve out of sediments or soils and can leach into the aquatic environment. These metals can • Bioaccumulate in fish tissues making them dangerous for humans to eat • Kill fish by damaging their gills (especially Al) • Acidification can cause the conversion of moderately toxic inorganic Hg to the highly toxic organic methylmercury

  41. Other Environmental Effects • Deterioration of buildings, statues, and metals • Reduction of crop yields some crops are diminished and others are stimulated • Damage to forest productivity: • Most affected are conifers at high elevations • Direct damage to leaves • Increase in the solubility and leaching of soil-bound ions of Al, killing root hairs • Loss of essential plant nutrients (Ca, K, Mg) from the soil

  42. Effects of Acid Precipitation

  43. Pollution Control Efforts • By the 1960s large-scale fuel-switching from coal to natural gas and oil had significantly reduced smoky conditions in most Am. Cities • Bans on home refuse burning & utilization of pollution control devices further reduced air pollution • Early air quality laws relied on voluntary compliance by states, many of which were reluctant to adopt strict controls for fear of driving away industry (jobs, tax-base, etc…) • Pollution levels continued to rise until the public outcried

  44. Clean Air Act • Spurred by the environmental movement, Congress passed the 1970 CAA. • Strengthened in early 1990’s by Bush • Has the following provisions: 1. Development of the NAAQS for the 6 criteria air pollutants *penalties were set for nonattainment areas

  45. Clean Air Act 2. Emission limitations for new stationary sources (factories and power plants) *NOT retroactive for stationary sources in operation prior to 1970 *required stationary sources to obtain operating permits specifying allowable levels of pollutant emission as well as required control measures

More Related