Chapter 15 Air Pollution

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A bowl is formed by the Appalachian Mountains and this makes it more susceptible to pollution, much like Boise inversions. Dense smog gets trapped and cannot rise above the mountains. Chapter 15 Air Pollution. - PowerPoint PPT Presentation

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  • Chapter 15Air PollutionA bowl is formed by the Appalachian Mountains and this makes it more susceptible to pollution, much like Boise inversions. Dense smog gets trapped and cannot rise above the mountains

  • Air pollution: chemicals, particulate matter, or microorganisms found in the atmosphere at concentrations high enough to harm plants, animals, and materials such as buildings or to alter ecosystems

  • Air pollutants are found throughout the entire global system. Air Pollution is the 5th largest killer in India.China, India, Africa

  • Major Air PollutantsSulfur dioxide SO2Nitrogen oxides NO or NO2 (NOx)Carbon oxides CO, CO2 (COx)Early air pollution legislation didnt care about CO2, Particulate matter (ash, dust, combustion of gas or diesel black smoke)

  • COPrevents O2 from attaching to hemoglobin in blood. Odorless, Colorless, It is created by incomplete combustion of gas and is found in car emissions

  • Particulate Matter (PM)

    PM ranges in size from .01m to PM10. PM2.5, is of great concern, because nose hair does not filter it out and it can become embedded in the lungs. Asbestos.

    PM can also scatter light.

  • Particulate Matter

  • PM can create what is called a haze or smog.

  • Amazon has haze from slash and burning of rainforest

  • Major Air PollutantsVolatile organic compounds (VOC)Ozone in troposphereLeadMercury

  • Sulfates are considered to be secondary pollutants because they are transformed from primary pollutants.

  • Gas can become a VOC because it evaporates at room temperature, leaving a strong smell, is a hydrocarbon that can leave PM, The combustion of coal is the primary cause of mercury in the air. Dry cleaner fluid, spilled gas lighter fluid are additional VOC.

  • Primary PollutantsPrimary pollutants: polluting compounds coming directly out of smoke-stacks, exhaust pipes, or natural emission source E.g., CO, CO2, SO2, NOx, and most suspended particulate matter

  • Secondary PollutantsSecondary pollutants: pollutants transformed in the presence of sunlight, water, oxygen or other compounds E.g., ozone, sulfate, and nitrate

  • Air pollution comes from both natural and human sources.

  • Natural Sources of Air PollutionVolcanoesLightningForest firesPlants

  • Anthropogenic Sources of Air PollutionAnthropogenic: From the Greek,Anthropos, human -genesis, createdMeaning anything caused or created by human activity

  • Anthropogenic Sources of Air PollutionOn-road vehiclesPower plantsIndustrial processesWaste disposal

  • Photochemical smog is still an environmental problem in the United States.

  • Smog FormationSmog forms when sunlight, nitrogen oxides (Nox), and volatile organic compounds (VOCs) are present.

    California smog is mostly due to ozone and called brown smog. London has SO2 smog and is called tea and crumpets smog. Ok, I made that up, it is gray smog.

  • Smog FormationThe secondary pollutant ozone is a major component of photochemical smog.Sulfur is the main ingredient in sulfurous smog.

  • Photochemical Smog

  • Thermal InversionsThermal Inversion: a relatively warm layer of air at mid-altitude covers a layer of cold, dense air below.The warm inversion layer traps emissions (pollutants) that then accumulate beneath it.

  • Acid DepositionThese secondary pollutants further break down into nitrate and sulfate, which create the acid in acid deposition.

  • Acid DepositionAcid deposition: nitrogen oxides and sulfur oxides released into the atmosphere combine with atmospheric oxygen and water.These become the secondary pollutants nitric acid and sulfuric acid.

  • Acid Deposition

  • Metamorphic differences due to acid rain during development and pollution in the soil.

  • Effects of Acid DepositionLowers the pH of lake waterDecreases species diversity in aquatic ecosystemsMobilizes metals found in soils and releases these into surface watersDamages statues, monuments, and buildings and other structures

  • Pollution control includes prevention, technology, and innovation.Nitrates are produced in combustion of coal and gas. By reducing the temperature of burning the coal and gas, less NOx is produced

  • Ways to Prevent Air PollutionRemoving sulfur dioxide from coal by fluidized bed combustionCatalytic converters on cars Acatalytic converteris avehicle emissions controldevice that converts toxicpollutantsin exhaust gasto less toxic pollutants, bycatalyzingaredoxreaction(oxidation or reduction). Catalytic converters are used ininternal combustion enginesfueled by eithergasoline ordieselincludinglean burn engines.Scrubbers on smoke stacksBaghouse filtersElectrostatic precipitators

  • Why is there no leaded-gasoline anymore?The metals in the catalytic converter (platinum and palladium) cannot be exposed to lead to work properly. This lead to less lead and CO, NO in atm.

  • Baghouse filter removes particles by using a series of filters. It is the most common means of removing particle pollution.

  • Particles given a negative charge, after attaching to plate, it is disposed of.

  • Particles are scrubbed from the exhaust stream by water droplets. The sludge is collected and disposed of. All three filters requires additional energy and emit heat pollution. They are very expensive to prevent PM air pollution

  • The stratospheric ozone layer provides protection from ultraviolet radiation.Ultra Violet has 3 sub wavelengths of energy

    UV-A passes through atm. w/o being absorbed and can cause skin cancer.

    UV-B, UV-C can cause severe tissue damage, DNA damage,

    Ozone blocks 99% of UV-B and UV-C

  • Stratospheric Ozone The stratospheric ozone layer exists roughly 45-60 kilometers above the Earth.Ozone has the ability to absorb ultraviolet radiation and protect life on Earth.

  • Formation and Breakdown of OzoneUV-C radiation breaks the bonds holding together the oxygen molecule, leaving two free oxygen atoms: O2 + UV-C 2 OSometimes these free oxygen atoms produce ozone: O2 + O O3Ozone breaks down into O2 and free oxygen atoms when it absorbs both UV-C and UV-B light: O3 + UV-B + UV-C O2 + O

  • Anthropogenic Contributions to Ozone DestructionCertain chemicals can break down ozone, particularly chlorine.The major sources of chlorine in the stratosphere are compounds known as chlorofluorocarbons (CFCs).CFCs are used in refrigeration and air conditioning, as propellants in aerosol cans, and as blowing agents to inject air into foam products like Styrofoam.

  • Anthropogenic Contributions to Ozone DestructionCFCs released into the troposphere disperse into the stratosphere.

  • Anthropogenic Contributions to Ozone DestructionIn the stratosphere, UV radiation has enough energy to break the bond connecting chlorine to the CFC molecule, producing Cl atoms.The Cl atoms act as catalysts and can break apart the ozone molecules.

  • Anthropogenic Contributions to Ozone DestructionInitially, chlorine breaks ozones bonds and pulls off one atom of oxygen, forming a chlorine monoxide molecule and O2: O3 + Cl ClO + O2Next, a free oxygen atoms pulls the oxygen atom from ClO, liberating the chlorine atom and creating one oxygen molecule: ClO + O Cl + O2

  • Anthropogenic Contributions to Ozone DestructionOne chlorine atom can catalyze the breakdown of as many as 100,000 ozone molecules before it leaves the stratosphere.This depletes the ozone layer.

  • Depletion of the Ozone LayerGlobal ozone concentrations have decreased by more than 10%.Depletion is greatest at the poles.Decreased stratospheric ozone has increased the amount of UV-B radiation that reaches the surface of Earth.

  • Indoor air pollution is a significant hazard, particularly in developing countries.More die from indoor air pollution than out door air pollution(2nd hand smoke)90% of deaths attributed to indoor pollution are in developing countries. 56% of those deaths are children under 5

  • Indoor Air PollutantsWood, animal manure or coal used for cooking and heating in developing countries.Lack of indoor ventilation can lead to carbon monoxide (CO) poisoning and increase in particulates in the air.This increases the risk for respiratory diseases such as infections and even cancer.

  • Indoor Air Pollutants

    In developed countries, people are spending more time inside.Houses are sealed more tightly for better insulation.This results in increased exposure to a number of indoor air pollutants.

  • Indoor Air Pollutants

    Asbestos: insulating mineral fiber found in older buildings, which must be removed by professionals.Carbon Monoxide: CO detectors should be installed where natural gas or wood stoves are used, as CO is odorless.

  • Indoor Air Pollutants

    Radon: radioactive gas released by some rocks into the soil, and migrates into homes in certain areas of the country.VOCs: many home products can give off these solvent fumes, such as building materials, plastics, and fabrics and carpets.

  • Review QuestionsDefine air pollution. What are several types of major air pollutants?What is carbon monoxide, and why is it so dangerous?What is smog?

  • Review Questions5. What is the difference between a primary and a secondary pollutant?What are some natural sources of air pollution?Give some examples of anthropogenic air pollution.

  • Review QuestionsHow do thermal inversions form? Why are they important in air pollution events? How does smog form? Define acid deposition. Describe some effects of acid deposition. What are some methods used to reduce air pollution?

  • Review Questions What is the stratospheric ozone layer? How does it form? Why is this layer important to humans and other organisms? What are some indoor air pollution problems in (a) developing and (b) developed countries?

    **Key Idea #1: Identify the major air pollutants and where they come from.********************Key Idea #2: Explain how photochemical smog and acid deposition are formed and describe the effects of each.***********Key Idea #3: Examine various approaches to the control and prevention of outdoor air pollution.******Key Idea #4: Explain the causes and effects of stratospheric ozone depletion.**********Key Idea #5: Discuss the hazards of indoor air pollution, especially in developing countries.*********