Week 4 Air Quality Issues & Waste Mgt PDF

 The most significant local variation in Earth’s temperature is produced because the sun’s energy does not reach all places uniformly.  A combination of Earth’s roughly spherical shape and the tilt of its axis produces variation in the exposure of the surface to the sun’s energy.  The princi...

 The most significant local variation in Earth’s temperature is produced because the sun’s energy does not reach all places uniformly.  A combination of Earth’s roughly spherical shape and the tilt of its axis produces variation in the exposure of the surface to the sun’s energy.  The principal effect of the tilt is on the angles at which the sun’s rays strike different areas of the planet at any one time.  On average, the sun’s rays hit vertically near the equator, making the energy more concentrated and producing higher temperatures.  Near the poles, the sun’s rays hit more obliquely; as a result, their energy is spread over a larger surface area. Also, rays of light entering the atmosphere obliquely near the poles pass through a deeper envelope of air than does light entering near the equator.  This causes more of the sun’s energy to be scattered and reflected back to space, which in turn further lowers temperatures near the poles. Thus, solar energy that reaches polar regions is less concentrated, and temperatures are lower.  Seasons are determined primarily by Earth’s inclination on its axis. Earth’s inclination on its axis is 23.5 degrees from a line drawn perpendicular to the orbital plane.  During half of the year (March 21 to September 22) the Northern Hemisphere tilts toward the sun, and during the other half (September 22 to March 21) it tilts away from the sun.  The orientation of the Southern Hemisphere is just the opposite at these times. Summer in the Northern Hemisphere corresponds to winter in the Southern Hemisphere. Figure 5.9 Progression of seasons. Earth’s inclination on its axis remains the same as it travels around the sun. The sun’s rays hit the Northern Hemisphere obliquely during its winter months and more directly during its summer. In the Southern Hemisphere, the sun’s rays are oblique during its winter, which corresponds to the Northern Hemisphere’s summer. At the equator, the sun’s rays are approximately vertical on March 21 and September 22.  LEARNING OBJECTIVES  Describe the four layers of Earth’s atmosphere: troposphere, stratosphere, mesosphere, and thermosphere.  The atmosphere is an invisible layer of gases that envelops Earth. Oxygen (21%) and nitrogen (78%) are the predominant gases in the atmosphere, accounting for about 99% of dry air.  Other gases, including argon, carbon dioxide, neon, and helium, make up the remaining 1%. In addition, water vapor and trace amounts of various air pollutants, such as methane, ozone, dust particles, microorganisms, and chlorofluorocarbons (CFCs), are present in the air.  The atmosphere becomes less dense as it extends outward into space; as a result of gravity, most of the atmosphere’s mass is found near Earth’s surface.  The atmosphere performs several ecologically important functions.  It protects Earth’s surface from most of the sun’s ultraviolet radiation and X-rays as well as from lethal amounts of cosmic rays from space. Without this shielding by the atmosphere, most life would cease to exist. While the atmosphere protects Earth from high-energy radiation, it allows visible light and some infrared radiation to penetrate, and they warm the surface and the lower atmosphere.  This interaction between the atmosphere and solar energy is responsible for weather and climate.  Organisms depend on the atmosphere, but they maintain and, in certain instances, modify its composition. Atmospheric oxygen is thought to have increased to its present level as a result of millions of years of photosynthesis.  A balance between oxygen producing photosynthesis and oxygen-using respiration maintains the current level of oxygen. Figure 5.10 Density of the atmosphere. Earth’s atmosphere decreases in density and pressure with increasing altitude. The force of gravity is responsible for attracting more air molecules closer to Earth’s surface.  The atmosphere is composed of a series of four concentric layers—  the troposphere,  stratosphere,  mesosphere,  and thermosphere  The troposphere extends to a height of approximately 12 km (7.5 mi).  The temperature of the troposphere decreases with increasing altitude by about – 6ºC (–11ºF) for every kilometer.  Weather, including turbulent wind, storms, and most clouds, occurs in the troposphere.  In the next layer of atmosphere, the stratosphere, there is a steady wind but no turbulence.  Little water is found in the stratosphere, and the temperature is more or less uniform (–45ºC to – 75ºC) in the lower stratosphere; commercial jets fly here.  The stratosphere extends from 12 km to 50 km (7.5 mi to 30 mi) above Earth’s surface and contains a layer of ozone critical to life because it absorbs much of the sun’s damaging ultraviolet radiation.  The absorption of ultraviolet radiation by the ozone layer heats the air, and so temperature increases with increasing altitude in the stratosphere.  The mesosphere, the layer of atmosphere directly above the stratosphere, extends from 50 km to 80 km (30 mi to 50 mi) above Earth’s surface.  Temperatures drop steadily in the mesosphere to the lowest in the atmosphere—as low as –138ºC.  The thermosphere extends from 80 km to 480 km (50 mi to 300 mi) and is very hot.  Gases in the thin air of the thermosphere absorb X-rays and short- wave ultraviolet radiation.  This absorption drives the few molecules present to great speeds, raising their temperature in the process to 1000ºC or more.  The aurora, a colorful display of lights in dark polar skies, is produced when charged particles from the sun hit oxygen or nitrogen molecules in the thermosphere.  The thermosphere is important in long-distance communication because it reflects outgoing radio waves back to Earth without the aid of satellites.  Weather refers to the conditions in the atmosphere at a given place and time; it includes temperature, atmospheric pressure, precipitation, cloudiness, humidity, and wind.  Weather changes from one hour to the next and from one day to the next.  Climate refers to the average weather conditions that occur in a place over a period of years.  The two most important factors that determine an area’s climate are temperature— both average temperature and temperature extremes—and precipitation—average precipitation, seasonal distribution, and variability.  Other climate factors include wind, humidity, fog, and cloud cover.  Precipitation refers to any form of water, such as rain, snow, sleet, and hail, that falls from the atmosphere.  Precipitation varies from one location to another and has a profound effect on the distribution and kinds of organisms present.  One of the driest places on Earth is in the Atacama Desert in Chile, where the average annual rainfall is 0.05 cm (0.02 in).  Incontrast, Mount Waialeale in Hawaii, Earth’s wettest spot, receives an average annual precipitation of 1200 cm (472 in.).  Air Quality Issues Air Pollution: Types & Sources of Air Pollution, Effects of Air Pollution  Air Quality Issues Air quality issues refer to the presence of pollutants in the air that pose risks to human health, the environment, and the climate. These pollutants can come from natural sources, but most are the result of human activities. What is the composition of atmosphere? The atmosphere is a gaseous envelope surrounding Earth Excluding water vapor, four gases comprise most of the atmosphere: nitrogen (N2, 78.08%), oxygen (O2, 20.95%), argon (Ar, 0.93%), and carbon dioxide (CO2, 0.04%). pollutants, occur in much smaller concentrations. Air pollution: Various chemicals added to the atmosphere by natural events or human activities in high enough concentrations to be harmful. gases, liquids, or solids present in the atmosphere in high enough levels to harm humans, other organisms, or materials Although air pollutants can come from natural sources—as when lightning causes a forest fire or a volcano erupts— human activities release many kinds of substances into the atmosphere and make a major contribution to air pollution. Some of these substances are harmful when they precipitate (form a solid) and settle on land and surface waters, whereas other substances are harmful because they alter the chemistry of the atmosphere. Air pollution released by humans is concentrated in densely populated urban areas. Primary air pollutant: A harmful substance, such as soot or carbon monoxide, that is emitted directly into the atmosphere. Although many different air pollutants exist, we will focus on the seven most important types from a regulatory perspective: particulate matter, nitrogen oxides, sulfur oxides, carbon oxides, hydrocarbons, ozone, and air. Secondary air pollutant: A harmful substance formed in the atmosphere when a primary air pollutant reacts with substances normally found in the atmosphere or with other air pollutants. MAJOR CLASSES OF AIR POLLUTANTS Particulate matter consists of thousands of different solid and liquid particles suspended in the atmosphere. Solid particulate matter is generally referred to as dust, whereas liquid suspensions are commonly called mists. Particulate matter includes a variety of pollutants, such as soil particles, soot, lead, asbestos, sea salt, and sulfuric acid droplets. Particulate matter reduces visibility by scattering and absorbing sunlight. Urban areas receive less sunlight than rural areas, partly as a result of greater quantities of particulate matter in the air. Particulate matter corrodes metals, erodes buildings and sculptures when the air is humid, and soils clothing and draperies. First, it may contain materials—such as heavy metals, asbestos, or organic chemicals—that have toxic or carcinogenic effects. These toxins, upon contacting or being absorbed into the body, have a range of effects. Second, extremely small particles, even if not toxic, can get lodged deep in the lungs.  MAJOR CLASSES OF AIR POLLUTANTS Lead, a soft metal that is used in industrial and chemical processes, has a variety of health impacts. Acute lead poisoning rarely results from outdoor exposure, but chronic effects can include permanently reduced cognitive ability, behavioral problems, slowed growth, hearing problems, and headaches. Airborne lead can be a problem both when it is inhaled and when it settles—in water and on surfaces including foods. MAJOR CLASSES OF AIR POLLUTANTS Nitrogen oxides are gases produced by the chemical interactions between atmospheric nitrogen and oxygen when a source of energy, such as combustion of fuels, produces high temperatures. Collectively known as NOx, nitrogen oxides consist mainly of nitric oxide (NO), nitrogen dioxide (NO2), and nitrous oxide (N2O). Nitrogen oxides inhibit plant growth and, when breathed, aggravate health problems such as asthma, a disease in which breathing is wheezy and labored because of airway constriction. They are involved in the production of photochemical smog and acid deposition (when nitrogen dioxide reacts with water to form nitric acid and nitrous acid). Nitrous oxide is associated with global warming (nitrous oxide traps heat in the atmosphere and is therefore a greenhouse gas) and depletes ozone in the stratosphere. Nitrogen oxides cause metals to corrode and textiles to fade and deteriorate. MAJOR CLASSES OF AIR POLLUTANTS Sulfur oxides are gases produced by the chemical interactions between sulfur and oxygen. Sulfur dioxide (SO2), a colorless, nonflammable gas with a strong, irritating odor, is a major sulfur oxide emitted as a primary air pollutant. Another major sulfur oxide is sulfur trioxide (SO3), a secondary air pollutant that forms when sulfur dioxide reacts with oxygen in the air. Sulfur trioxide, in turn, reacts with water to form another secondary air pollutant, sulfuric acid. Sulfur oxides cause acid deposition, and they corrode metals and damage stone and other materials. Sulfuric acid and sulfate salts produced in the atmosphere from sulfur oxides damage plants and irritate the respiratory tracts of humans and other animals. MAJOR CLASSES OF AIR POLLUTANTS Carbon oxides are the gases carbon monoxide (CO) and carbon dioxide (CO2). Carbon monoxide, a colorless, odorless, and tasteless gas produced in the largest quantities of any atmospheric pollutant except carbon dioxide, is poisonous and interferes with the blood’s ability to transport oxygen. Carbon dioxide, also colorless, odorless, and tasteless, is a greenhouse gas; its buildup in the atmosphere is associated with global climate change. MAJOR CLASSES OF AIR POLLUTANTS Hydrocarbons - organic compounds - hydrogen and carbon; the simplest hydrocarbon is methane (CH4). Small hydrocarbon molecules are gaseous at room temperature. Methane is a colorless, odorless gas that is the principal component of natural gas. (The odor of natural gas comes from sulfur compounds deliberately added so that humans can indirectly detect the presence of the explosive methane gas by smelling the sulfur-containing compounds.) Medium-sized hydrocarbons such as benzene (C6H6) are liquids at room temperature, although many are volatile and evaporate readily. The largest hydrocarbons, such as the waxy substance paraffin, are solids at room temperature. A variety of effects on human and animal health; injure the respiratory tract, and still others cause cancer. All except methane are important in the production of photochemical smog. Methane is a potent greenhouse gas linked to global climate change. MAJOR CLASSES OF AIR POLLUTANTS Ozone (O3) is a form of oxygen considered a pollutant in one part of the atmosphere but an essential component in another. In the stratosphere, which extends from 12 to 50 km (7.5 to 30 mi) above Earth’s surface, oxygen reacts with UV radiation coming from the sun to form ozone. Stratospheric ozone prevents much of the solar UV radiation from penetrating to Earth’s surface. Unfortunately, certain human-made pollutants (chlorofluorocarbons, or CFCs) react with stratospheric ozone, breaking it down into molecular oxygen, O2. Ozone in the troposphere is a secondary air pollutant that forms when sunlight catalyzes reactions between nitrogen oxides and volatile hydrocarbons. The most harmful component of photochemical smog, ozone reduces air visibility and causes health problems. Ozone stresses plants and reduces their vigor, and chronic (of long duration) ozone exposure lowers crop yields Chronic exposure to ozone is a possible contributor to forest decline, and ground-level ozone is a greenhouse gas associated with global climate change. SOURCES OF OUTDOOR AIR POLLUTION The two main human sources of primary air pollutants are transportation (mobile sources) and industries (stationary sources). Automobiles and trucks, known as mobile sources, generate significant quantities of nitrogen oxides, carbon oxides, particulate matter, and hydrocarbons as a result of the combustion of gasoline. Although diesel engines in trucks, buses, trains, and ships consume less fuel than other types of combustion engines, they produce more air pollution. One heavy-duty truck emits as much particulate matter as 15 automobiles, whereas one diesel train engine produces, on average, 10 times the particulate matter of a diesel truck. Pollutants from engines used in outboard motorboats, jet skis, and other mobile sources cause both air and water pollution. Electric power plants and other industrial facilities, known as stationary sources, emit most of the particulate matter and sulfur oxides released in the United States; they emit sizable amounts of nitrogen oxides, hydrocarbons, and carbon oxides. The combustion of fossil fuels, especially coal, is responsible for most of these emissions. The top three industrial sources of toxic air pollutants—that is, chemicals released into the air that are fatal to humans at specified concentrations—are the chemical industry, the metals industry, and the paper industry. URBAN AIR POLLUTION Air pollution localized in urban areas, where it reduces visibility, is often called smog. The word smog was coined at the beginning of the 20th century for the smoky fog that was so prevalent in London because of coal combustion. Today there are several different types of smog. Traditional London-type smog—that is, smoke pollution—is sometimes called industrial smog. The principal pollutants in industrial smog are sulfur oxides and particulate matter. The worst episodes of industrial smog typically occur during winter months, when combustion of household fuel such as heating oil or coal is high. In December 1952, 4000 Londoners died in the world’s worst industrial smog incident. An additional 8000 people died within the next two months, possibly due to the lingering effects of the smog, although the exact causes of death for these people have never been explained. Because of air quality laws and pollution-control devices, industrial smog is generally not a significant problem in highly developed countries today, but it is often serious in many communities and industrial regions of developing countries. Hazardous air pollutants: Air pollutants that are potentially harmful photochemical smog: A brownish-orange and may pose long-term health risks to haze formed by chemical reactions involving sunlight, nitrogen oxide, and people who live and work around hydrocarbons. chemical factories, incinerators, or other facilities that produce or use them. Photochemical smog - brownish-orange smog is called photochemical because light—that is, sunlight—initiates several chemical reactions that collectively form its ingredients. First noted in Los Angeles in the 1940s, photochemical smog is generally worst during the summer months. Both nitrogen oxides and hydrocarbons are involved in its formation. One of the photochemical reactions occurs among nitrogen oxides (largely from automobile exhaust), volatile hydrocarbons, and oxygen in the atmosphere to produce ground level ozone; this reaction requires solar energy. The ozone formed in this way then reacts with other air pollutants, including hydrocarbons, to form more than 100 different secondary air pollutants (peroxyacyl nitrates, or PANs, for example) that injure plant tissues, irritate eyes, and aggravate respiratory illnesses in humans. Effects of Air pollution Air pollution injures organisms, reduces visibility, and attacks and corrodes materials such as metals, plastics, rubber, and fabrics. The respiratory tracts of animals, including humans, are particularly harmed by air pollutants, which worsen existing medical conditions such as chronic lung disease, pneumonia, and cardiovascular problems. Most forms of air pollution reduce the overall productivity of crop plants, and when combined with other environmental stressors, such as low winter temperatures or prolonged droughts, air pollution causes plants to decline and die. Air pollution is involved in acid deposition, global climate changes, and stratospheric ozone depletion. AIR POLLUTION AND HUMAN HEALTH Generally speaking, exposure to even low levels of pollutants such as ozone, sulfur oxides, nitrogen oxides, and particulate matter can irritate eyes and inflame the respiratory tract. Evidence shows that many air pollutants suppress the immune system, increasing susceptibility to infection. In addition, evidence continues to accumulate that exposure to air pollution during respiratory illnesses may result in the development later in life of chronic respiratory diseases, such as emphysema and chronic bronchitis Health Effects of Specific Air Pollutants Both sulfur dioxide and particulate matter irritate the respiratory tract and, because they cause the airways to constrict, actually impair the lungs’ ability to exchange gases. People suffering from emphysema and asthma are sensitive to sulfur dioxide and particulate pollution. Nitrogen dioxide also causes airway constriction and, in people suffering from asthma, an increased sensitivity to pollen and dust mites (microscopic animals found in household dust). Health Effects of Specific Air Pollutants  Children and Air Pollution Air pollution is a greater health threat to children than it is to adults. Can restrict lung development, making children more vulnerable to health problems later in life. A child has a higher metabolic rate than an adult and needs more oxygen. To obtain this oxygen, a child breathes more air—about two times as much air per pound of body weight as an adult. This means that a child breathes more air pollutants into the lungs. A 1990 study in which autopsies were performed on 100 Los Angeles children who died for unrelated reasons found that more than 80% had early-stage lung disease. Children who breathe the most polluted air (higher concentrations of nitrogen dioxide, particulate matter, and acid vapor) have less lung growth than children who breathe cleaner air. If the children moved to areas with less particulate air pollution, their lung development increased, but if they moved to areas with worse particulate air pollution, their lung development decreased. Exposure to lead is also a particular concern for young children. It can slow development and lead to permanent reductions in mental ability.  Waste Management Waste management refers to the processes involved in handling waste from its generation to its disposal, with the goal of reducing its environmental and health impacts. Effective waste management involves several stages, including collection, transportation, treatment, and disposal of waste. The major types of waste include household waste, industrial waste, hazardous waste, agricultural waste, and electronic waste (e-waste). Key Types of Waste: 1.Municipal Solid Waste (MSW): Everyday items discarded by households, businesses, and institutions (e.g., food scraps, packaging, paper, and plastics). Key Types of Waste: 2. Industrial Waste: Generated from manufacturing, mining, and other industries, often including hazardous materials. Key Types of Waste: 3. Hazardous Waste: Contains toxic substances that can be dangerous to human health and the environment (e.g., chemicals, batteries, medical waste). Key Types of Waste: 4. E-waste: Discarded electronic items like computers, phones, and TVs, which can contain harmful materials like lead and mercury. Key Types of Waste: 5.Agricultural Waste: Produced from farming and includes manure, crop residues, and pesticides. 1. Collection 2. Sorting and segregation: 3. Transportation: 4. Recovery 5. Disposal Waste Management Methods: 1.Landfilling: The most common method, where waste is buried in designated land areas. Modern landfills are designed to minimize environmental impact by preventing leaching of harmful chemicals into the ground and water. However, they still contribute to greenhouse gas emissions (methane) and can cause long-term environmental damage. Waste Management Methods: 2.Incineration: Burning waste at high temperatures to reduce its volume and mass. This method can generate energy, but it releases pollutants into the atmosphere, such as dioxins and heavy metals, unless emissions are carefully controlled. Waste Management Methods: 3.Recycling: Recovering materials from waste products and reprocessing them into new products. Commonly recycled materials include paper, plastic, glass, and metals. Recycling reduces the need for raw materials and minimizes waste in landfills. Waste Management Methods: 4.Composting: Organic waste (e.g., food scraps, yard waste) is broken down into a nutrient-rich soil additive. This method reduces landfill waste and promotes sustainable agriculture. Waste Management Methods: 5. Waste-to-Energy (WtE): A process where waste is burned to produce electricity or heat. Though it reduces waste volumes, it can also emit harmful gases if not properly managed. Waste Management Methods: 6. Bioremediation: Using microbes or plants to break down hazardous waste materials in soil or water. This method can be useful for treating contaminated sites. Waste Management Methods: 7. Source Reduction: Efforts to reduce the generation of waste in the first place by changing consumption patterns, improving product design, or using fewer materials. Challenges in Waste Management: Increasing Waste Volumes: As populations grow and consumption rises, managing larger amounts of waste becomes a critical issue. Inefficient Recycling Systems: In many regions, recycling rates are low due to lack of infrastructure, public awareness, or economic incentives. Hazardous Waste Management: Handling toxic and hazardous materials safely is a complex and costly process, requiring specialized disposal techniques. E-waste: With rapid technological advancements, discarded electronics are piling up, leading to significant environmental and health risks, particularly in regions where safe recycling methods are not available. Impacts of Poor Waste Management: Environmental: Improperly managed waste can pollute water bodies, soil, and air. For example, plastic waste in oceans harms marine life, and toxic leachates from landfills can contaminate groundwater. Public Health: Exposure to improperly handled waste, especially hazardous and medical waste, can lead to diseases, respiratory issues, and long-term health complications. Economic: Inefficient waste management systems can lead to increased costs for governments and businesses, while also reducing the lifespan of landfills and increasing the need for expensive clean-up efforts. Sustainable Waste Management Practices: 1.Circular Economy: This approach emphasizes reusing, repairing, refurbishing, and recycling products and materials to create a closed-loop system, reducing the need for raw materials and waste. 2.Zero Waste Movement: A philosophy aimed at eliminating waste by redesigning systems to make it possible to reuse all resources without sending them to landfills or incinerators. 3.Extended Producer Responsibility (EPR): A policy approach where manufacturers are made responsible for the end-of-life disposal of their products. This can encourage the design of products that are easier to recycle or reuse. 4.Public Awareness Campaigns: Encouraging communities to reduce waste, recycle more, and engage in sustainable practices like composting.