Environmental Science and Sustainability Ch8 - Air PDF

CHAPTER 8 Air: What Are We Breathing? Copyright © 2023 W. W. Norton & Company, Inc. Chapter 8 Outline 8.1 What Makes Up the Air We Breathe and Our Atmosphere? 8.2 What Is Weather and How Does It Change? 8.4 How Does the Atmosphere Become Polluted? 8.6 What Is Acid Rain? 8.7 How Are We Respondi...

CHAPTER 8 Air: What Are We Breathing? Copyright © 2023 W. W. Norton & Company, Inc. Chapter 8 Outline 8.1 What Makes Up the Air We Breathe and Our Atmosphere? 8.2 What Is Weather and How Does It Change? 8.4 How Does the Atmosphere Become Polluted? 8.6 What Is Acid Rain? 8.7 How Are We Responding to Pollution in the Atmosphere? Chapter Objectives: This chapter will help you… name the most prominent gases found in the atmosphere. describe how the four layers of Earth’s atmosphere are distinguished by varying characteristics. explain what an air mass is and how it rises, falls, and circulates with changes in temperature, moisture, and wind conditions. define and provide examples of primary and secondary pollutants. describe how secondary pollutants in the atmosphere react to cause smog, ozone layer depletion, and acid deposition (acid rain). compare and contrast different policies aimed at improving air quality. 8.1 What Makes Up the Air We Breathe and Our Atmosphere? The air around us is actually a mixture of many gases. Earth’s atmosphere is mostly composed of constantly moving gases, and contains 78% nitrogen (N2), 20% oxygen (O2), and smaller amounts of argon, carbon dioxide (C02), water vapor, and other compounds. These atoms and molecules in the form of gases continually bounce around, collide in, and fill whatever space or volume is available. How Is Earth’s Atmosphere Structured? (1 of 3) The atmosphere is divided into four layers with different pressures, temperatures, and compositions. Most of the atmosphere’s mass is within a 5- to 10-mile-thick layer above Earth known as the troposphere. The troposphere holds most of the water vapor in the atmosphere. The air in this layer is dynamic and creates our weather conditions. How Is Earth’s Atmosphere Structured? (2 of 3) The next layer, extending 30 miles above the troposphere, is the stratosphere, which contains the ozone layer. Stratospheric ozone absorbs ultraviolet solar radiation, which has a warming effect on the stratosphere, while shielding life below from damage. How Is Earth’s Atmosphere Structured? (3 of 3) The next layer, the mesosphere, lies above the stratosphere and has the coldest temperatures, which fall as low as –148°F. Above the mesosphere is the thermosphere, which is warmer due to solar and cosmic radiation, and less dense due to low levels of gravity. Aurora Take-Home Message The air in our atmosphere is a combination of gases that envelop Earth. The four main layers of the atmosphere support life by producing weather, containing the air we breathe, and filtering harmful ultraviolet radiation. 8.2 What Is Weather and How Does It Change? Weather refers to short-term variations in conditions such as temperature, moisture, and wind in a specific place. Weather is different from climate, which is the long-term average (usually 30 years) of weather conditions for a given region. Temperature Temperature is a measure of hotness or coldness of something using a thermometer. Earth is warmed by the Sun due to solar radiation reaching Earth’s surface. Temperature variations across Earth’s surface are mostly due to changes in the amount of radiation at various latitudes. Land and water features also affect temperature variations. Large bodies of water heat up and cool down slowly. This means coastal area temperatures change less than areas farther inland. Wind, Fronts, and Storms Wind is air in motion as it flows from high-pressure to low-pressure areas. Wind is a major force in regulating the hydrologic (precipitation) cycle Take-Home Message Weather is defined as the short-term variations in temperature, moisture, and wind conditions. Climate is defined as the long-term average of weather conditions for a given region. Weather is impacted by differences in solar energy received and by elevation, where landmasses are located, and proximity to bodies of water. Air masses rise, fall, and circulate horizontally according to changes in temperature, pressure, and water vapor content. This creates wind and local weather patterns. 8.4 How Does the Atmosphere Become Polluted? In Chapter 3, we learned how matter is conserved, so when we burn wood or fuel, the matter doesn’t “go away”; instead, it changes form and persists as emissions in the atmosphere. When the addition of materials into the atmosphere adversely affects the health of humans and/or other organisms, we consider this air pollution. The effects of outdoor air pollution are influenced by atmospheric circulation patterns. Primary Pollutants (1 of 3) A primary pollutant is a substance that is harmful in its directly emitted form. A common primary pollutant we are exposed to is carbon monoxide (CO) in car exhaust from incomplete combustion when a car idles. Other examples of pollutants in the atmosphere include agricultural pesticides, benzene from gasoline production, and asbestos from construction. This photo shows incomplete combustion – if a flame has enough oxygen, it burns hot and blue. A yellow flame indicates the flame is burning cooler and producing carbon monoxide. Primary Pollutants (2 of 3) Particulate matter (PM) is a form of air pollution made up of tiny particles and droplets less than 10 micrometers (μm) in size that are suspended in the air we breathe and can cause respiratory ailments. The smallest particulate matter particles can be especially dangerous since they can be absorbed by the lungs and enter the blood stream. Primary Pollutants (3 of 3) Other examples of primary pollutants are toxic metals such as lead, mercury, and arsenic, which can travel in airborne particles. Lead is a neurotoxin that can accumulate in the body and cause delays in mental and physical development, as well as kidney damage. Volatile organic compounds (VOCs) result from fossil fuel burning or using carbon-based compounds like paint or solvents. These VOCs can be found in higher concentrations indoors. Common VOCs are formaldehyde, toluene, and acetone, which can cause eye, nose, and throat irritation as well as headaches after prolonged exposure. Secondary Pollutants (1 of 2) Secondary pollutants are the product of reactions occurring in the atmosphere. Smog is a mixture of secondary pollutants resulting from reactions between sunlight and chemicals in the atmosphere. Smog forms when VOCs and nitrogen oxides (NOx) from fossil fuel combustion interact with sunlight at warm temperatures. Ground level ozone can damage animal lung tissue and chlorophyll in plants. Secondary Pollutants (2 of 2) In normal conditions, air is usually warm at the surface and gets cooler at higher altitudes. Thermal inversion happens in some urban areas and involves warm air capping a cooler layer of air below, which prevents air circulation. This results in polluted air becoming trapped over a surface area for an extended period. Take-Home Message Air pollution is the addition of materials into the atmosphere that affect the health of humans and/or other organisms. Primary pollutants are directly harmful in their emitted form. Secondary pollutants are produced by reactions that occur in the atmosphere. Landforms can worsen pollution by trapping it in a localized area. 8.6 What Is Acid Rain? (1 of 2) Normal rainwater is slightly acidic pH of 5.6. In the 1970s, rising sulfur dioxide (SO2) and nitrogen oxide (NOx) levels emitted into the atmosphere from human sources like car exhaust, agricultural and industrial processes reacted with water vapor to form sulfuric acid (H2SO4) and nitric acid (HNO3). Acid deposition is the acid created from these air pollutants around the world that then precipitates from the sky. This is also known as “acid rain.” What Is Acid Rain? (2 of 2) Acid deposition has changed the pH of thousands of lakes in eastern Canada and New England. Freshwater lakes have a natural pH between 6 and 8, and lower pH levels due to acid precipitation are affecting developmental stages and physical development of insect and fish species. Acid deposition changes soil pH and important soil microbes, affecting plant growth and mortality. Acid deposition wears away human structures and artwork, especially limestone and marble ones. AT A GLANCE Air Pollution Take-Home Message Acid rain occurs when sulfur dioxide and nitrogen oxides react with water vapor in the atmosphere or water at ground level to form acidic solutions. Ecosystems are negatively impacted by acid which can alter the pH of soil and water. The effects of acid deposition can be felt far from the source of the pollution. 8.7 How Are We Responding to Pollution in the Atmosphere? (1 of 3) Policy strategies addressing air pollution in the United States have been successful, seen in the reduction of many pollutants even as the country experienced increased population growth. The Clean Air Act of 1970 is a law in the United States that established two important policy strategies: air quality standards and regulations of the source of pollutants. Under the Clean Air Act, the Environmental Protection Agency assesses health risks for common pollutants in the air to determine maximum allowable concentrations of each. 8.7 How Are We Responding to Pollution in the Atmosphere? (3 of 3) In 1990, amendments to the Clean Air Act of 1970 added a new policy strategy, the tradeable emission allowance policy, where the EPA sets the total allowable annual emissions for a pollutant from utilities, then divides this total into tradeable units called allowances, which are bought and sold. This is an example of the US cap-and-trade policy strategies, which are market-driven strategies. Some air pollution policies attempt to influence commuters and consumers, like bus and carpool lanes on major commuter routes and fuel efficiency car labels. Take-Home Message Concerted federal action to address air pollution in the United States began with the Clean Air Act of 1970. Policy strategies to address air pollution include establishing and monitoring air-quality standards, regulating air pollution sources, establishing tradable permits for pollutants, and creating incentives to influence commuter and consumer behavior. Question 1 What gas composes the largest portion of Earth's atmosphere? A. oxygen B. nitrogen C. sulfur D. hydrogen Question 1 Answer What gas composes the largest portion of Earth's atmosphere? A. oxygen B. nitrogen (Correct) C. sulfur D. hydrogen Question 2 Typical patterns of atmospheric conditions in a specific location over years, decades, and longer time periods are described by _________________. A. climate B. sunspots C. the moon D. weather Question 2 Answer Typical patterns of atmospheric conditions in a specific location over years, decades, and longer time periods are described by _________________. A. climate (Correct) B. sunspots C. the moon D. weather Question 3 Morning commutes in urban areas can result in which type of secondary air pollution? A. ozone depletion B. acid rain C. smog D. carbon monoxide Question 3 Answer Morning commutes in urban areas can result in which type of secondary air pollution? A. ozone depletion B. acid rain C. smog (Correct) D. carbon monoxide Question 4 Which of the following is a successful market-driven mechanism for addressing air pollution in the United States? A. international treaties from global conferences B. carbon taxes C. carbon neutrality D. cap-and-trade Question 4 Answer Which of the following is a successful market-driven mechanism for addressing air pollution in the United States? A. international treaties from global conferences B. carbon taxes C. carbon neutrality D. cap-and-trade (Correct) Credits This concludes the Lecture PowerPoint presentation for Environmental Science and Sustainability, Chapter 8, by David Montgomery and Daniel Sherman For more resources, please visit https://digital.wwnorton.com/environsci2 Copyright © 2023 W. W. Norton & Company, Inc.