sustn- 100 exam 2

Mineral

An inorganic solid, occurring naturally in or on Earth's crust, with characteristic chemical and physical properties.

Indicator species

An organism that provides an early warning of environmental damage. Examples include lichens, which are sensitive to air pollution, and amphibians, which are sensitive to pesticides and other environmental contaminants.

Seed banks

(1) the stock, in species and abundance, of plant seeds in soil; (2) a place where plant seeds are stored in case of future need.

Sustainable city

A city with a livable environment, a strong economy, and a social and cultural sense of community; sustainable cities enhance the well‐being of current and future generations of urban dwellers.

Endemic

A disease that is constantly present, although often varying in prevalence and potency, in a region or population.

Suburban sprawl

A patchwork of vacant and developed tracts around the edges of cities; contains a low population density.

Habitat corridors

A protected zone that connects unlogged or undeveloped areas; wildlife corridors are thought to provide escape routes and allow animals to disperse so they can interbreed. Also called wildlife corridor.

Gentrification

A shift in an urban community toward more affluent residents and businesses; accompanied by increased property values and possibly increased property taxes.

Endangered species

A species that faces threats that may cause it to become extinct within a short period.

Strip mining

A type of surface mining in which a trench is dug to extract the minerals, then a new trench is dug parallel to the old one; the overburden from the new trench is put into the old trench, creating a hill of loose rock known as a spoil bank.

Mineral conservation

Conservation, including both reuse and recycling, extends mineral supplies. The reuse of items such as beverage bottles, which are collected, washed, and refilled, is one way to extend mineral resources. In recycling, used items such as beverage cans and scrap iron are collected, remelted, and reprocessed into new products. In addition to promoting specific conservation techniques such as reuse and recycling, public awareness and attitudes about resource conservation can be modified to encourage low waste. Reuse When the same product is used over and over again, both mineral consumption and pollution are reduced. The benefits of reuse are greater than those of recycling (see Chapter 23). Recycling a glass bottle requires crushing it, melting the glass, and forming a new bottle. Reusing a glass bottle simply requires washing it, which typically expends less energy than recycling. Reuse is a national policy in Denmark, where nonreusable beverage containers are prohibited. Several countries and states have adopted beverage container deposit laws, which require consumers to pay a deposit, usually a nickel or dime, for each beverage bottle or can that they purchase. The deposit is refunded when the container is returned to the retailer or to special redemption centers. Unredeemed deposits are generally used to provide revenue for environmental programs such as hazardous waste cleanups. In addition to encouraging reuse and recycling, thereby reducing mineral resource consumption, beverage container deposit laws save tax money by reducing litter and solid waste. Countries that have adopted beverage container deposit laws include the Netherlands, Germany, Norway, Sweden, and Switzerland, as well as parts of Canada and the United States. Recycling A large percentage of the products made from minerals—such as cans, bottles, chemical products, electronic devices, and batteries—is typically discarded after use. The minerals in some of these products—batteries and electronic devices, for instance—are difficult to recycle. Minerals in other products, such as paints containing lead, zinc, or chromium, are lost through normal use. However, the technology exists to recycle many other mineral products. Recycling of certain minerals is already a common practice throughout the industrialized world, including the United States, but there is much room for improvement (Table 15.3). TABLE 15.3 Recycling Rates for Metals in the United States, 2014 Mineral Percent Recycled Aluminum 52 Copper 33 Iron and Steel 50 Lead 68 Magnesium 46 Titanium 63 Source: USGS 2014 Minerals Yearbook. Recycling has several advantages beyond extending mineral resources. It saves unspoiled land from the disruption of mining, reduces the amount of solid waste that must be disposed of, and decreases energy consumption and pollution. Recycling an aluminum beverage can saves the energy equivalent of about 180 mL (6 oz) of gasoline. Recycling aluminum reduces the emission of aluminum fluoride, a toxic air pollutant produced during the processing of aluminum ore. About 64% of the aluminum cans in the United States were recycled in 2015, as reported by an industry association. Aluminum cans contain three times more recycled content than glass or plastic bottles, and they can be recycled over and over again. The aluminum industry, local governments, and private groups have established thousands of recycling centers across the country. It takes approximately six weeks for a used can to be melted, re‐formed, filled, and put back on a supermarket shelf. Clearly, even more recycling is possible. It may be that today's sanitary landfills will become tomorrow's mines, as valuable minerals and other materials are extracted from them. (In many countries, sanitary landfills are already treated as mines.) Changing Our Mineral Requirements We can reduce mineral consumption by becoming a low‐waste society. U.S. citizens have developed a "throwaway" mentality wherein damaged or unneeded articles are discarded. Industries looking for short‐term economic profits encourage this attitude, even though the long‐term economic and environmental costs of it are high. We consume fewer resources if products are durable and repairable. Laws such as those requiring a deposit on beverage containers reduce consumption by encouraging reuse and recycling. The throwaway mentality is also evident in manufacturing industries. Traditionally, industries consume raw materials and produce goods and a large amount of waste that is simply discarded (Figure 15.13a). Increasingly, manufacturers are finding that the waste products from one manufacturing process can become the raw materials for another industry. By selling these "wastes," industries gain additional profits and lessen the amounts of materials that must be discarded.

Global Water Problems

Data on global water availability and use indicate that the amount of fresh water on the planet is adequate to meet human needs, even taking population growth into account. These data, though, do not consider the distribution of water resources in relation to human populations. For example, citizens of Bahrain, a tiny island nation in the Persian Gulf, have no freshwater supply and must rely on desalination of ocean water. Per capita water use varies greatly from country to country and from continent to continent, depending on the size of the human population and the available water supply. South America and Asia receive more than one‐half of the world's renewable fresh water (by precipitation). Although South America has more available water per person than Asia does, it does not have the potential to support as many people as its water supply would suggest. Most of South America's precipitation falls in the Amazon River basin, which has soil that is largely unsuited to conventional large‐scale agriculture. In contrast, because most of the precipitation in Asia falls on land more suitable to conventional agriculture, the water supply supports more people. Humans need an adequate supply of water year‐round. In some places, stable runoff, the portion of runoff from precipitation available throughout the year, is low even though total runoff is quite high. India's wet season—June to September—produces 90% of its annual precipitation. Most of the water that falls during India's monsoon quickly drains away into rivers and is unavailable during the rest of the year. Thus, India's stable runoff is low. Variation in annual water supply is an important factor in certain areas of the world. The African Sahel region (see Figure 4.22) has wet years and dry years, and the lack of water during the dry years limits human endeavors during the wet years. Since the late 1960s, the Sahel has experienced an ongoing drought that has had a devastating impact on the people and wildlife living in the region. Water and Climate Change climate Climate change will play an important role in future freshwater availability, as precipitation is expected to increase in some areas while it drops in others. Changes in rainfall may lead to abrupt changes in available surface water, since runoff is influenced by geologic factors such as soil permeability and biological factors such as amount of vegetation. One study indicated that a 10% decrease in rainfall in one part of Africa would lead to a 17% reduction in runoff, while the same precipitation decrease in another area would lead to a 50% reduction in runoff. This means that climate change will impact water supply more severely in some areas than in others. The study concluded that predicted variations in rainfall due to climate change will affect available surface water for one‐fourth of the African continent by 2100. Issues with water availability in turn hamper agriculture in affected parts of Africa, challenging researchers and farmers to adapt to variable water supplies. Climate change will affect available fresh water in other ways as well. The type of precipitation is important: Earlier, we noted how reduced snowfall in the Rocky Mountains and Sierra Nevada will impact water availability in the American West and Southwest. Sea‐level rise—caused by thermal expansion and surface ice melt—has already caused saltwater intrusion into drinking‐water sources for certain low‐lying island nations. Environmental Connections Climate Change and Crops in Southern Africa Researchers have carried out extensive modeling and analyses to predict future effects of climate change on agriculture in southern Africa, with findings published by the International Food Policy Research Institute. The rising temperatures and erratic precipitation associated with climate change are considered a real threat to the region's crop yields. Hot, dry conditions reduce soil moisture content and curb the growing season, effects that are expected to cause declines in average yields of major crops such as maize and sorghum. The increased variability in precipitation is proving particularly threatening to crop production. Most farms in the region are small operations, and farmers depend on rainfall to water their crops. Adaptations to changing conditions may include planting different, more drought‐resistant crops. Drinking‐Water Problems Many inhabitants of developing countries have insufficient water to meet the most basic drinking and household needs. The water exists—only about 1% of the Earth's water would suffice for the entire human population. However, this water is not available to many people; they have to spend large amounts of money or travel great distances to secure the water they need. Individual governments, the United Nations, the World Bank,1 nongovernmental organizations (NGOs), and civic organizations all sponsor water projects in developing countries. As described in the chapter opener, the UN Development Programme (UNDP) estimates that 663 million people lack access to safe drinking water Approximately 2.4 billion live without satisfactory sanitation services such as a latrine or toilet. These people risk disease because sewage or industrial wastes contaminate the water they consume; in fact, at least 1.8 billion of the world's people obtain drinking water from a fecally contaminated source. The World Health Organization (WHO) estimates that 80% of human illness results from insufficient water supplies and poor water quality caused by lack of sanitation. Nearly 1,000 children are estimated to die each year as a result of diarrheal diseases contracted through contaminated water and poor sanitation. Although many affected countries have installed or are installing public water systems, population increases can overwhelm efforts to improve the water supply. Population Growth and Water Problems As the world's population continues to increase, global water problems are becoming more serious. Earth's people and its water resources are often not concentrated in the same places, and severe climate events such as drought or flooding disrupt nations' abilities to provide stable water supplies, causing water stress (Interactive Figure 13.16). Interactive Figure 13.16 Global water stress In a 2013 World Resources Institute assessment, a nation's water supply is considered stressed if the ratio of water withdrawals to total water supply is high, meaning that water may be scarce for communities, farms, and industries. Thirty‐six countries face "extremely high" levels of water stress. (Several of these are small enough to not be easily visible here.) Question Which regions are most likely to experience high water stress? Asia has the world's largest available water resources—36% of the Earth's total. However, it is also home to 60% of the world's people, and the water resources are not evenly distributed across the population. In India, 18% of the world's population has access to only 4% of the world's fresh water. Thousands of villages have no local water, and more than half of the nation's groundwater wells are decreasing. Water supplies are precarious in large portions of China, owing to population pressures. The water table across much of the North China Plain, with a population more than twice that of the United States, is falling rapidly. Much of the water in the Yellow River is diverted for irrigation, leaving downstream areas with little or no water. Over the past several decades, the Yellow River has run dry hundreds of kilometers inland before it reaches the Yellow Sea. Iraq faces a particular geographical challenge: Headwaters of both the Tigris and the Euphrates rivers originate outside the country's borders. While current conflicts in Iraq overshadow the water issue, shortages in both quality and quantity of water remain an internal challenge. Water supply will continue to influence Iraq's relations with neighboring countries, especially those upstream, including Turkey, Syria, Jordan, and Saudi Arabia as well as Iran, with which Iraq has had armed conflicts for decades. Mexico has long faced serious water shortages. The main aquifer supplying Mexico City is dropping as much as 3.5 m (about 11 ft) per year. Aging infrastructure and rapid population growth there have driven many people to live along hillsides where they can access water delivered on trucks. The water table in Guanajuato, an agricultural state in Mexico, is also falling rapidly. Water stress isn't necessarily an unsolvable problem, and many nations, including some under extreme water stress, manage water resources effectively. These countries typically lack high rates of poverty. Singapore has a dense population and minimal water supplies, yet its investments in technology, international agreements, and conservations strategies allow it to meet its freshwater demands. Sharing Water Resources Among Countries Surface water is often an international resource. Around 260 of the world's major watersheds are shared between at least two nations. International cooperation is required to manage rivers that cross international borders. The Rhine River Basin The drainage basin for the Rhine River in Europe is primarily in five highly developed and densely populated countries—Switzerland, Germany, France, Luxembourg, and the Netherlands (Figure 13.17). Traditionally, Switzerland, Germany, and France used water from the Rhine for industrial purposes and then discharged polluted water back into the river. The Netherlands—which in 2010 got 82% of its water from beyond its borders—then had to clean up Humans remove so much water from the Amu Darya, Ganges, Indus, Nile, Yellow, and Colorado Rivers that their channels run dry during at least some parts of the year. Tensions are high along the Mekong River basin, shared by Laos, Thailand, and Vietnam, and the Indus River basin, shared between Pakistan and India. India and Bangladesh quarrel over the Ganges River. Slovakia and Hungary both depend on the Danube River. Developing cooperative international agreements on shared water resources is an urgent global issue. The Jordan River, which supplies water to Israel, Jordan, the West Bank, and the Gaza Strip, experienced a 90% reduction in flow between 1960 and 2010. Water use continues to increase because of population growth, agriculture, and industry. A collaborative study by the U.S. National Academy of Sciences, the Israel Academy of Sciences and Humanities, the Palestine Academy for Sciences and Technology, and the Royal Scientific Society of Jordan concluded that the future outlook in the region continues to be one of significant water stress. Participants urged their respective governments to cooperate in developing conservation measures such as reusing wastewater. Nonetheless, differential access between Israeli settlers on the West Bank, who use far more water than the neighboring Palestinians, provides a significant source of conflict. Northeastern Africa has a serious water‐use situation: the Nile River. Egypt uses most of the Nile's water (and has for millennia), even though 10 nations share the Nile River basin. Ethiopia and Sudan are expanding their use of the Nile River's flow to meet the demands of their rapidly growing populations; these actions could imperil Egypt's freshwater supply at a time when its population is increasing. The United Nations engineered an international water‐use agreement among the Nile River countries to help diffuse this potentially dangerous water situation, and the 10 nations in the region have formed the Nile Basin Initiative to review past agreements and work together to manage and develop their shared water resources.

Conservation biology

The scientific study of how humans impact organisms and of the development of ways to protect biological diversity.

Urban ecology

The study of living organisms and their habitats within urban environments.

Extinction and species endangerment

Extinction, the death of all individuals of a species, occurs when the last individual member of a species dies. Extinction is an irreversible loss: Once a species is extinct, it will never reappear. Biological extinction appears to be the eventual fate of all species, much as death is the eventual fate of all individuals. Biologists estimate that for every 2000 species that have ever lived, 1999 of them are extinct today. During the time span in which organisms have occupied Earth, a continuous, low‐level extinction of species, or background extinction, has occurred. At certain periods in Earth's history, maybe five or six times, there has been a second kind of extinction, mass extinction, in which numerous species disappeared during a relatively short period of geologic time. The course of a mass extinction episode may have taken millions of years, but that is a short time compared with the time that life has existed on this planet, which is estimated at about 3.5 billion years. The causes of past mass extinctions are not well understood, but biological and environmental factors were probably involved. A major climate change could have triggered the mass extinction of species. Marine organisms are particularly vulnerable to temperature changes; if Earth's temperature changed just a few degrees, it is likely that many marine species would become extinct. It is possible that mass extinctions of the past were triggered by catastrophes, such as the collision of Earth with a large asteroid or comet. The impact could have forced massive quantities of dust into the atmosphere, blocking the sun's rays and cooling the planet. Although extinction is a natural biological process, it is greatly accelerated by human activities. The burgeoning human population has spread into almost all areas of Earth. Whenever humans invade an area, the habitats of many organisms are disrupted or destroyed, which contributes to their extinction. Currently, Earth's biological diversity is disappearing at an unprecedented rate (Figure 16.4). Conservation biologists estimate that species are presently becoming extinct at a rate of 100 to 1000 times the natural rate of background extinctions. The International Union for Conservation of Nature (IUCN) listed more than 24,000 species as threatened with extinction in 2016, including 13% of birds, 25% of mammals, and 42% of amphibians. About 11,600 species of plants are currently threatened with extinctions. In late 2016 and early 2017, bee species were listed as endangered for the first time, including seven yellow‐faced bee species in Hawaii, and a bumblebee species in the continental United States. (See Environmental Connections in Chapter 5 for more on threats to bee species, and turn to You Can Make a Difference 16.1: Addressing Declining Biological Diversity to determine how you can help reduce threats to species.)

Invasive species

Foreign species that spread rapidly in a new area where they are free of predators, parasites, or resource limitations that may have controlled their populations in their native habitat.

High and low grade ores

High- grade ore: An ore that contains relatively large amounts of a particular mineral. Low grade ores:An ore that contains relatively small amounts of a particular mineral.

Yucca Mountain

In 1954, before the first commercial nuclear power plant opened, the U.S. government decided to be responsible for all high‐level waste associated with electricity production. In 1982, passage of the Nuclear Waste Policy Act required the first site to be operational by 1998. It also legally required the U.S. government to take ownership of nuclear wastes. Since 1999, radioactive wastes from the manufacture of nuclear weapons have been stored permanently in deep underground salt beds at the Waste Isolation Pilot Project (WIPP) near Carlsbad, New Mexico. However, the deadline for completion of an operational high‐level radioactive civilian waste repository was postponed from 1998 to 2010 then to 2017—and it probably will be postponed again. In a 1987 amendment to the Nuclear Waste Policy Act, Congress identified Yucca Mountain in Nevada as the only candidate being formally considered as a permanent underground storage site for high‐level radioactive wastes from commercially operated power plants (Figure 12.20). Yucca Mountain could take the 42,000‐plus tons of spent fuel produced in the United States to date plus spent fuel that will be produced until about 2025. At that time, Yucca Mountain would be full, and a new geologic depository will be needed. If and when spent fuel is stored at Yucca Mountain, it will be in a huge complex of interconnected tunnels located in dense volcanic rock 300 m (1000 ft) beneath the mountain crest. Canisters containing high‐level radioactive waste may be stored in the tunnels. The U.S. Department of Energy (DOE) has spent billions of dollars conducting feasibility studies on Yucca Mountain's geology. Results indicate that the site is safe, at least from volcanic eruptions and earthquakes. However, the suitability of Yucca Mountain has been mired in scientific, management, cost, public opposition, and scheduling controversies, and Nevadans oppose the selection of their state for a radioactive waste site. In 2002 Congress finally approved the choice of Yucca Mountain as the U.S. nuclear waste repository, despite the state of Nevada's opposition. In 2004, U.S. federal courts decided that any permanent burial site must meet standards of the EPA for the next 1 million years—an increase from the previous 10,000‐year standard. Guaranteeing safety over a million‐year period stretches the credibility of any scientific assessment. In 2008, the DOE formally submitted its application for a license to operate the facility, but under the Obama administration, the application was withdrawn. For some time, the nuclear industry has been weighing whether to file a lawsuit to require that the process go forward. The Yucca Mountain site, some 145 km (90 mi) northwest of Las Vegas, is controversial in part because it is near a volcano (its last eruption may have occurred 20,000 years ago) and active earthquake fault lines. The possibility of a volcanic eruption at Yucca Mountain is currently considered remote (1 chance in 10,000 during the next 10,000 years). Concerns that earthquakes might disturb the site and raise the water table, resulting in radioactive contamination of air and groundwater, were examined when a magnitude 5.6 earthquake occurred in 1992 about 20 km (about 12 mi) from Yucca Mountain. Scientists were already monitoring water table elevation, and they measured a 1‐m change caused by the earthquake. The water table is some 800 m (2625 ft) beneath the mountain crest, so water elevation changes due to earthquake activity are not considered a serious problem by most (but not all) experts. Transporting high‐level wastes from nuclear reactors and weapons sites is a major concern of opponents of the Yucca Mountain site. The typical shipment would travel an average of 2300 miles, and 43 states would have these materials passing through on their way to Yucca Mountain. Eight states—Illinois, Indiana, Iowa, Kansas, Missouri, Nebraska, Utah, and Wyoming—would contain major transportation corridors to Yucca Mountain. Around the world, more than two dozen countries plan to store their spent uranium fuel in deep underground deposits. Many of these countries are facing similar challenges of public opposition to proposed sites. France, long considered a nuclear power success story, has been unable to select a permanent site. In Sweden, apparent agreement on a site came only after the country agreed to discontinue nuclear power—that decision has since been revisited as energy demand and climate change concerns increase.

Endangered Species Act and Habitat Conservation Plans

In 1973 the Endangered Species Act (ESA) was passed in the United States, authorizing the U.S. Fish and Wildlife Service (FWS) to protect endangered and threatened species in the United States and abroad. Many other countries now have similar legislation. The ESA requires a detailed study of a species to determine if it should be listed as endangered or threatened. Currently, more than 1600 species in the United States are listed as endangered or threatened. The ESA provides legal protection to listed species to help reduce their danger of extinction. This act makes it illegal to sell or buy any product made from an endangered or threatened species. The ESA requires the FWS to select critical habitats and design a detailed recovery plan for each species listed. The recovery plan includes an estimate of the current population size, an analysis of what factors contributed to its endangerment, and a list of activities to help the population recover. Currently, 1158 U.S. endangered or threatened species have approved recovery plans. The ESA was updated in 1982, 1985, and 1988. It is considered one of the strongest pieces of U.S. environmental legislation, in part because species are designated as endangered or threatened entirely on biological grounds. Currently, economic considerations cannot influence the designation of endangered or threatened species. Biologists generally agree that as a result of passage of the ESA in 1973, fewer species became extinct than would have if the law had not been passed. The ESA is one of the most controversial pieces of environmental legislation. It does not provide compensation for private property owners who suffer financial losses because they cannot develop their land if a threatened or endangered species lives there. The ESA has also interfered with some federally funded development projects. The ESA was scheduled for congressional reauthorization in 1992 but has been entangled since then in political wrangling between conservation advocates and those who support private property rights. Conservation advocates think the ESA does not do enough to save endangered species, whereas those who own land on which rare species live think the law goes too far and infringes on property rights. Another contentious issue is the financial cost of the law. Critics say that federal and state governments spend too much, given the little bit of environmental gain that the ESA accomplishes. Some critics—notably business interests and private property owners—view the ESA as an impediment to economic progress. The Trump administration has expressed strong support for this particular perspective on the ESA. Those who defend the ESA point out that nearly all of the approximately 34,000 past cases of endangered species versus economic development were resolved through some sort of compromise. Compromise is crucial to the success of saving endangered species because, according to the U.S. General Accounting Office, more than 90% of endangered species live on at least some privately owned lands. Some critics of the ESA think the law should be changed so that private landowners are given economic incentives to help save endangered species living on their lands. For example, tax cuts for property owners who are good land stewards could make the presence of endangered species on their properties an asset instead of a liability. Defenders of the ESA agree that the law is not perfect. Relatively few endangered species have recovered enough to be delisted—that is, removed from protection of the ESA (Figure 16.19). However, the FWS reports that hundreds of listed species are stable or improving; it expects as many as several dozen additional species to be delisted in the next decade or so. However, many species are considered conservation reliant—that is, they may never recover sufficiently to be delisted. The 1982 amendment of the ESA provided a way to resolve conflicts between protection of endangered species and development interests on private property: habitat conservation plans (HCPs). HCPs vary greatly, from small projects to regional conservation and development plans. Habitat conservation plans allow a landowner to "take" (injure, kill, or modify the habitat of) a rare species if the "taking" doesn't threaten the survival or recovery of the threatened or endangered species on that property. If a landowner sets aside land as habitat for the rare species, he or she then has the right to develop part of the property without threat of legal action by the FWS. Conservationists point out that HCPs do not provide any promise of recovery of rare species. In some cases, conservationists are concerned that HCPs may actually contribute to a species' extinction.

Restoration ecology

The study of the historical condition of a human‐damaged ecosystem, with the goal of returning it as close as possible to its former state.

Groundwater

The supply of fresh water under Earth's surface that is stored in underground aquifers.

4 energy policy objectives

Objective 1: Increase Energy Efficiency and Conservation Over the past several decades, the efficiency of many technologies has improved. But despite gains, global energy use continues to increase. Improvement must occur on many fronts, from individuals conserving heating oil by weatherproofing their homes, to groups of commuters conserving gasoline by carpooling, to corporations developing more energy‐efficient products. Often, it is difficult for individuals or companies to invest in purchases that reduce energy use in the long run if those investments are costly in the short run. Similarly, companies may not recover costs of research that leads to more efficient technologies. In other cases, individuals may not know about energy costs or available opportunities to reduce those costs. One objective of an effective energy policy, then, is to support or provide long‐term investment in conservation and efficiency while also informing citizens about true energy costs and alternatives. An energy policy that was effective, although controversial, was the nationwide 55‐mile‐per‐hour speed limit, which was the law in the United States from 1974 to 1995. Fuel consumption increases approximately 50% if a car is driven at 75 mph rather than at 55 mph. However, many Americans objected that the 55‐mph speed limit increased their travel times and that lost time was more expensive to businesses than were energy gains. By contrast, most cities and states have planning policies that promote large, unimpeded roads and freeways, a policy choice that encourages vehicle use. Objective 2: Secure Future Fossil‐Fuel Energy Supplies Environmental Science Basics: Fossil Fuels A comprehensive national energy strategy could include the environmentally sound and responsible development of domestically produced fossil fuels, especially natural gas. Three concerns exist about this element of a national energy strategy: security, economics, and the environment. Oil is an internationally traded commodity, and much of it comes from a small number of countries. Countries (including the United States) that import large quantities of oil are rightfully concerned about secure sources. Oil is a global commodity, so increasing oil production in any country increases the global supply but has a limited impact on that country's own supply. Everyone, environmentalists included, recognizes the need for a dependable energy supply. Securing a future supply of fossil fuels, whether domestic or foreign, is a temporary strategy because fossil fuels are nonrenewable resources that will eventually be depleted, regardless of how efficient our use or how much we conserve. In the United States, maintaining a secure energy supply for the short term should be balanced by developing alternative energy sources for the long term. Objective 3: Develop Alternative Energy Sources An effective long‐term energy strategy will focus on identifying, researching, and developing inexpensive, environmentally benign, and widely available energy resources. In the past few years, the cost of new electrical generation from solar and wind resources has dropped, driving increased investment in those resources. Additional research and incentives will increase the contribution of these renewable alternatives to global energy resources. A gasoline or carbon tax could finance programs to achieve a sustainable energy future. One recent policy change in the United States makes it easier for individual electricity consumers to both sell energy back to the grid and buy it from the grid. Early private adopters of rooftop solar panels had to keep their units independent from the grid, since it was difficult to ensure that the quality of electricity produced was the same as that coming from the grid. Modern solar panel designs, however, convert electricity to a form compatible with the grid. An increasing number of consumers are now able to watch their power meters run backward as they supply electricity to the grid! Objective 4: Meet Previous Objectives Without Further Damage to The Environment We must weigh the environmental costs of using a particular energy source against its benefits when it is considered as a practical component of an energy policy. Any country can require that its domestic supplies of fossil fuels be developed with as much attention to the environment as possible. This may make those fuels less competitive on the global market, but it would bring the benefit of a better quality of life for the citizens of that country. One option in the United States is a 5‐cent tax on each barrel of domestically produced oil or ton of domestically produced coal to establish a reclamation fund for some of the environmental damage caused by drilling or mining, production, and refining. This could be accompanied by a similar tariff on oil and coal imported from countries that do not have similar requirements.

Offshore drilling/Deepwater Horizon

On April 22, 2010, the Deepwater Horizon, a drilling platform in the Gulf of Mexico, exploded. As the platform collapsed, its equipment detached from the Macondo oil well, 1500 m (about 6000 ft) below the surface and 90 km (50 mi) from the southern coast of the United States. Massive quantities of oil began to gush from the well, spreading across the seafloor and up to the surface. British Petroleum (the company that owned the platform) used a variety of strategies to try to seal the wellhead. After many unsuccessful attempts, the flow of oil was finally stopped in mid‐July of 2010. Between the explosion and July 15, when flow was completely stopped, around 5 million barrels (210 million gallons) of oil gushed from the well. Lighter than water, most of this oil rose to the surface, where wind and currents spread it widely. At its maximum, the oil slick covered an area of nearly 75,000 km2 (29,000 mi2). Oil reached the southern coast of Mississippi by early May and the Louisiana coast shortly thereafter (Interactive Figure 11.17a). Several techniques were used to remove the oil from the ocean surface and shores, including deploying a fleet of over 6,000 ships and boats to scoop up or divert the oil, setting fires to burn oil, and applying dispersants that act like dish soap to prevent the oil from concentrating.

Environmental Impacts of Refining Minerals

On average, approximately 80% or more of mined ore consists of impurities that become wastes after processing (Table 15.2). These wastes, called tailings, are usually left in giant piles on the ground or in ponds near the processing plants (Figure 15.5a). The tailings contain toxic materials such as cyanide, mercury, uranium, and sulfuric acid. Left exposed in this way, these toxic substances contaminate the air, soil, and water (Figure 15.5b). Heavy metals in mine tailings at the Bunker Hill Superfund site in northern Idaho, for example, have leached (washed) into the south fork of the Coeur d'Alene River, killing fish and waterfowl. TABLE 15.2 Ore and Waste Production for Selected Minerals Mineral Amount of Mined Ore (Million Tons) Percentage of Ore That Becomes Waste During Refining* Iron ore 2958 60 Copper 1663 99 Gold 745 99.99 Lead 267 97.5 Aluminum 128 81 * Data do not include the overburden of rock and soil that originally covered the ore deposits. Source: Adapted from Table 6.4 on page 117 in G. Gardner, et al. State of the World, 2003. New York: W.W. Norton & Company (2003) and based on data from U.S. Geological Survey and Worldwatch. w0402-0403-c FIGURE 15.5 Environmental impact of disposed tailings. Source: J.K. Otton, R.A. Zielinski, and R.J. Horton. Geology, Geochemistry, and Geophysics of the Fry Canyon Uranium/Copper Projects Site, Southeastern Utah—Indications of Contaminant Migration. U.S. Geological Survey Scientific Investigations Report 2010-5075 (2010). Smelting plants have the potential to emit large quantities of air pollutants during mineral processing. One impurity in many mineral ores is sulfur. Unless expensive pollution‐control devices are added to smelters, the sulfur escapes into the atmosphere, where it forms sulfuric acid. The environmental implications of the resulting acid precipitation are discussed in Chapter 19. Pollution‐control devices for smelters are the same as those used when sulfur‐containing coal is burned—scrubbers and electrostatic precipitators (see Figure 19.9). See Case in Point: Copper Basin, Tennessee, for a stark example of environmental degradation caused by smelting operations. Case in Point | Copper Basin, Tennessee Copper Basin, Tennessee, in the southeast corner of Tennessee, near its borders with Georgia and North Carolina, is a historic example of environmental degradation caused by smelting. Until relatively recently, the Copper Basin area progressed from lush forests to a panorama of red, barren hills baking in the sun (Figure 15.6a). Few plant or animal species could be found—just 130 km2 (50 mi2) of hills with deep ruts gouged into them. How did this degradation occur? p0404-0405-c FIGURE 15.6 Environmental devastation near Ducktown, Tennessee. During the middle of the 19th century, copper ore was discovered near Ducktown in southeastern Tennessee. Copper mining companies extracted the ore from the ground and dug vast pits to serve as open‐air smelters. They cut down the surrounding trees and burned them in the smelters to produce the high temperatures needed to separate copper metal from other contaminants in the ore. The ore contained great quantities of sulfur, which reacted with oxygen in the air to form sulfur dioxide. As sulfur dioxide from the smelters billowed into the atmosphere, it reacted with water, forming sulfuric acid that fell as acid precipitation. The deforestation and acid precipitation triggered ecological ruin of the area within a few short years. Acid precipitation quickly killed any plants attempting a comeback after removal of the forests. Because plants no longer covered the soil and held it in place, soil erosion cut massive gullies into the gently rolling hills. Of course, the forest animals disappeared with the plants, which had provided their shelter and food. The damage did not stop there. Soil eroding from the Copper Basin, along with acid precipitation, ended up in the Ocoee River, killing its entire aquatic community. Beginning in the 1920s and 1930s, several government agencies, including the Tennessee Valley Authority and the U.S. Soil Conservation Service, tried to replant a portion of the area. They planted millions of loblolly pine and black locust trees as well as shorter ground‐cover grasses and legume plants that tolerate acid conditions, but most of the plants died. The success of such efforts was marginal until the 1970s, when land reclamation specialists began using new techniques such as application of seed and time‐released fertilizer by helicopter. These plants had a greater survival rate, and as they became established, their roots held the soil in place. Leaves dropping to the ground contributed organic material to the soil. The plants provided shade and food for animals such as birds and field mice, which slowly began to return. Today, reclamation of Copper Basin continues under a 2001 agreement between the state of Tennessee and the U.S. Environmental Protection Agency, with the goal of having the entire area under plant cover (Figure 15.6b). (Of course, the forest ecosystem's full recovery will take at least a century or two.) Water treatment efforts are also restoring the Ocoee River, where fish and invertebrates are returning. Other contaminants found in many ores include the heavy metals lead, cadmium, arsenic, and zinc. These elements have the potential to pollute the atmosphere during the smelting process. Cadmium, for example, is found in zinc ores, and emissions from zinc smelters are a major source of environmental cadmium contamination. In humans, cadmium is linked to high blood pressure; diseases of the liver, kidneys, and heart; and certain types of cancer. In addition to airborne pollutants, smelters emit hazardous liquid and solid wastes that can cause soil and water pollution. Pollution‐control devices prevent such hazardous emissions, although the toxic materials captured must be safely disposed of or they will still cause environmental pollution.

Sustainable Water Use

The use of water resources in a fashion that does not harm the essential functions of the hydrologic cycle or the ecosystems on which present and future humans depend.

Colorado River Basin

One of the most serious water supply problems in the United States is in the Colorado River basin. The river's headwaters are formed from snowmelt in Colorado, Utah, and Wyoming, and its major tributaries—collectively called the upper Colorado—extend throughout these states. The lower Colorado River runs through part of Arizona and then along the border between Arizona and both Nevada and California before crossing into Mexico and emptying into the Gulf of California. The Colorado River provides some or all of the water used by 35-40 million people, including the cities of Denver, Las Vegas, Albuquerque, Phoenix, Los Angeles, San Diego, and Salt Lake City. It irrigates 1.8 million hectares (4.5 million acres) of fruit, vegetable, and field crops that together with animal production are worth approximately $5 billion per year. The Colorado River has 49 dams, 11 of which produce electricity by hydropower. More than 30 Native American tribes live along the Colorado River and claim rights to some of its water. The river provides $1.5 billion per year in revenues from almost 30 million people who use it for recreation. The most important of all the treaties regulating use of Colorado River water is the 1922 Colorado River Compact. It stipulates an annual allotment of 7.5 million acre‐feet of water to the lower Colorado (California, Nevada, Arizona, and New Mexico) and the remainder to the upper Colorado (Colorado, Utah, and Wyoming). However, the Colorado River Compact overestimated the average annual flow of the Colorado River, which at the time was thought to be 15 million acre‐feet. This overallocation was enshrined in the multistate agreement. Mexico receives a share of the Colorado River, as stipulated by a 1944 treaty. Consequently, the Colorado River water is often completely consumed before it can reach the Pacific Ocean, causing serious problems for the ecosystem and inhabitants of the Colorado River delta (Figure 13.13). To compound the problem, as more and more water is used, the lower Colorado becomes increasingly salty as it flows toward Mexico; in places, the Colorado River is saltier than the ocean. As a result of diversion for irrigation and other uses in the United States, the Colorado River usually dries up before reaching the Gulf of California in Mexico. Over the decades, competing demands on Colorado River water have produced renegotiations between parties and redrawn allocations. Prolonged drought in the region has compounded the conflict but also contributed to greater water conservation and recent decreases in per capita water use. Colorado River basin stakeholders continue to work together to address water supply and demand imbalances.

Tailings

Piles of loose rock produced when a mineral such as uranium is mined and processed (extracted and purified from the ore).

Acid mine drainage

Pollution caused when sulfuric acid and dissolved materials such as lead, arsenic, and cadmium wash from coal and metal mines into nearby lakes and streams

Water Conservation

Population and economic growth place an increased demand on Earth's water supply. Today there is more competition than ever among water users with different priorities, and water conservation measures are necessary to guarantee sufficient water supplies. Most water users use more water than they really need, whether it is for agricultural, industrial, or direct personal consumption. With incentives, these users will lower their rates of water consumption. Many studies have shown that programs combining increased prices for water, improved technology, and effective educational tools motivate consumers to conserve water. Reducing Agricultural Water Waste Irrigation generally makes inefficient use of water. Traditional irrigation methods practiced for more than 5000 years involve flooding the land or diverting water to fields through open channels. Plants absorb about 40% of the water applied to the soil by flood irrigation; the rest usually evaporates into the atmosphere or seeps into the ground. One of the most important innovations in agricultural water conservation is microirrigation, also called drip or trickle irrigation, in which pipes with tiny holes bored in them convey water directly to individual plants (Figure 13.23). Microirrigation substantially reduces the water needed to irrigate crops, usually by 40% to 60% compared to center‐pivot irrigation or flood irrigation, and it also reduces the amount of salt left in the soil by irrigation water. p0338 FIGURE 13.23 Microirrigation Cutaway view of soil shows a small tube at the root line. Tiny holes in the tube deliver a precise amount of water directly to roots, eliminating much of the waste associated with traditional methods of irrigation. Photographed in Fresno, California. Another important water‐saving measure in irrigation is the use of lasers to level fields, allowing a more even water distribution. As a laser beam sweeps across a field, a field grader receives the beam and scrapes the soil, leveling it. Because farmers must use extra water to ensure that plants growing at higher elevations of a field receive enough, laser leveling of a field reduces the water required for irrigation. A technology that has advanced significantly in the past few years is a combination of low‐energy precision application (LEPA) irrigation and geographic information systems (GIS). LEPA involves dragging hoses across fields in a computer‐controlled pattern. Water is released only when and where needed. Less water pumped and sprayed means less energy used, less evaporation, and less runoff of unused water. GIS uses signals from satellites to identify locations for irrigation within 20 cm (8 in.) or less of the target plants. LEPA and GIS irrigation in parts of Texas has allowed an eightfold water use reduction. The use of sound water management principles in agriculture reduces water consumption. Traditionally, western farmers were allotted specific amounts of water at specific times, with a "use it or lose it" philosophy. This approach encourages waste. Instead, a field's water needs should be carefully monitored (by measuring rainfall and soil moisture) to determine when to irrigate and how much water to apply. These water management strategies effectively reduce overall water consumption. Although advances in irrigation technology are improving the efficiency of water use, many challenges remain. For one thing, sophisticated irrigation techniques are expensive. Few farmers in highly developed countries, let alone subsistence farmers in developing nations, can afford to install them. Another challenge is that irrigation needs to make much greater use of recycled wastewater instead of fresh water that could be used for direct human consumption. Reducing Industrial Water Waste Electric power generators and many industries require water (recall from Chapters 10 to 12 that power plants heat water to form steam, which turns the turbines). In the United States, five major industries—chemical products, paper and pulp, petroleum and coal, primary metals, and food processing—consume almost 90% of industrial water. Water use by these industries does not include water used for cooling purposes. Stricter pollution‐control laws provide some incentive for industries to conserve water. Industries usually recapture, purify, and reuse water to reduce their water use and their water treatment costs. For example, in 2010, Jackson Family Wines in California implemented a water recycling system estimated to eventually save the winery up to 6 million gallons of water annually while reducing energy usage; in 2015 the winery launched efforts to restore diminished creeks and populations of juvenile trout and salmon supported by the creeks. It is likely that water scarcity, in addition to more stringent pollution‐control requirements, will encourage further industrial recycling. The potential for industries to conserve water by recycling is enormous.

Agriculture and water

Population growth in arid and semiarid regions intensifies water shortage. More people need food, so additional water resources are diverted for irrigation. Also, the immediate need for food prompts people to remove natural plant cover to grow crops on marginal lands subject to frequent drought and subsequent crop losses. Livestock overgraze the small amount of plant cover in natural pastures. The resulting bare soil cannot absorb the water as well when the rains do come, and runoff is greater. Because the precipitation does not replenish the soil, crop productivity is poor and people are forced to cultivate food crops on additional marginal land. Removing too much fresh water from a river or lake can have disastrous consequences in local ecosystems. Humans can remove perhaps 30% of a river's flow without greatly affecting the natural ecosystem. In some places, however, considerably more is withdrawn for human use. In the arid American Southwest, 70% or more of surface water is often removed. When surface water is overdrawn, wetlands dry up. Natural wetlands play many roles, such as serving as a breeding ground for many species of birds and other animals. Estuaries, where rivers empty into seawater, become saltier when surface waters are overdrawn, and this change in salinity reduces the productivity associated with estuaries. Aquifer depletion from excessive removal of groundwater lowers the water table. Prolonged aquifer depletion can empty an aquifer, eliminating it as a water resource. In addition, aquifer depletion from porous sediments causes subsidence, or sinking, of the land above it. Some areas of the San Joaquin Valley in California have sunk as much as 8.5 m (28 ft) since the 1920s, including ongoing subsidence rates (2015-2016) as high as 0.6 m (2 ft) per year. The limestone bedrock of Florida erodes as groundwater moves through it, sometimes causing a sinkhole, a large surface cavity or depression where an underground cave roof has collapsed. Sinkholes occur more frequently when droughts or excessive pumping of water causes a lowering of the water table. Saltwater intrusion occurs along coastal areas when groundwater is depleted faster than it recharges (Figure 13.10). Saltwater intrusion is also occurring in low‐lying parts of the world due to sea‐level rise associated with global climate change. Well water in such areas eventually becomes too salty for human consumption or other uses. Once it occurs, saltwater intrusion is difficult to reverse. climate

Surface water

Precipitation that remains on the surface of the land and does not seep down through the soil.

Human causes of species endangerment

Scientists generally agree that the single greatest threat to biological diversity is land use change, which causes loss of habitat. The spread of invasive species, overexploitation, and pollution (including climate change from CO2 pollution) are also important factors contributing to declining global biological diversity. Underlying these direct causes of biological diversity loss are human population increase; increasing economic activity; increased use of technology; and social, political, and cultural factors (Interactive Figure 16.8). All of these direct and indirect factors interact in complex ways, and so it is most effective to deal with the problem of declining biological diversity using a systems perspective. Addressing a single factor, such as overexploitation, without considering the other factors that may amplify declining biological diversity is probably doomed to failure. The United Nations' Sustainable Development Goals (SDGs; see Chapter 8), particularly Goal 15, Life on Land, promote a coordinated global effort to end human threats to Earth's biological diversity. Interactive Figure 16.8 Causes of declining biological diversity In this highly simplified diagram, indirect causes (blue) interact with and amplify the effects of one another and of direct causes (purple). Land Use Change Most species facing extinction today are endangered because of the destruction, fragmentation, or degradation of habitats by human activities. We demolish or alter habitats when we build roads, parking lots, bridges, and buildings; log forests for timber; and clear forests to graze domestic animals or grow crops (Figure 16.9; also see Figure 17.11). We drain marshes to build on aquatic habitats, thus converting them to terrestrial ones, and we flood terrestrial habitats when we build dams with their reservoirs. Exploration and mining of minerals, including fossil fuels, disrupt the land and destroy habitats. Habitats are altered by outdoor recreation, including off‐road vehicles, hiking off‐trail, golfing, skiing, and camping. Because most organisms are utterly dependent on a particular type of environment, habitat destruction reduces their biological range and ability to survive. p0467 FIGURE 16.9 Land use change These soybean fields surround a small sliver of tropical rain forest. Photographed in Mato Grosso, Brazil. As the human population has grown, the need for increased amounts of food has resulted in a huge conversion of forests and other natural lands into croplands and permanent pastures. According to the UN Food and Agriculture Organization, total agricultural lands currently occupy 36% of Earth's land area (see Figure 17.1). Agriculture has a major impact on aquatic ecosystems because of the diversion of water for irrigation. Little habitat remains for many endangered species. The grizzly bear, for example, occupies about 2% of its habitat in the lower 48 states of the United States prior to European colonization. Human population growth and the extraction of resources have destroyed most of the grizzly's wilderness habitat. Habitat destruction, fragmentation, and degradation are happening around the world. As entire habitats are transformed for human purposes, many species are becoming extinct, and the genetic diversity within many surviving species is declining. Africa provides a vivid example of a systems issue—the conflict between humans and species such as elephants over land use. African elephants are nomads that require a lot of natural landscape in which to forage for the hundreds of kilograms of food that each consumes daily. In Africa, people are increasingly pushing into the elephants' territory to grow crops and graze farm animals. A study of 25 African regions with both wild areas and human settlements found that when human density increases to a certain level, the elephants migrate out of the area. The problem is that the wild areas to which elephants can move are steadily shrinking. One of the great challenges is finding a way to allow people and elephants to coexist in an increasingly crowded world. Invasive Species Biotic pollution, the introduction of a foreign species into an ecosystem in which it did not evolve, often upsets the balance among the organisms living in that area and interferes with the ecosystem's normal functioning. (See the chapter opener for an example in the Florida Everglades.) Unlike other forms of pollution, which may be cleaned up, biotic pollution is usually permanent. The foreign species may compete with native species for food or habitat or may prey on them. Generally, an introduced competitor or predator has a greater negative effect on local organisms than do native competitors or predators. Foreign species whose introduction causes economic or environmental harm are called invasive species (Interactive Figure 16.10). Interactive Figure 16.10 Invasive species Selected examples of the approximately 4300 established foreign species considered invasive, a subset of the tens of thousands of species that have been accidentally or deliberately introduced into the United States. Although invasive species may be introduced into new areas by natural means, humans are usually responsible for such introductions, either knowingly or unknowingly. The water hyacinth was deliberately brought from South America to the United States because it has lovely flowers. Today it has become a nuisance in Florida waterways, clogging them to such an extent that boats cannot easily move, and crowding out native species. Islands are particularly susceptible to the introduction of invasive species. The brown tree snake was accidentally introduced in Guam, an island in the West Pacific, shortly after the end of World War II. Thought to have arrived from the Solomon Islands on a U.S. Navy ship, the brown tree snake thrived and is now estimated to number about 2 million. It consumed rain‐forest birds in large numbers; as a result, 9 of Guam's 12 native species of forest birds are extinct in nature. The snakes have also decimated Guam's small reptiles and mammals. In 2013, the U.S. Department of Agriculture began experimental efforts to control the brown snake population by parachute‐dropping dead mice laced with acetaminophen, which is toxic to the snake but not to humans. The program is showing promising results, with some bird populations increasing. Overexploitation Sometimes species become endangered or extinct as a result of overharvest or deliberate efforts to reduce their numbers. Many of these species prey on game animals or livestock. Ranchers, hunters, and government agents have reduced populations of large predators such as the wolf and grizzly bear. Predators of game animals and livestock are not the only animals vulnerable to human control efforts. Some animals are killed because their lifestyles cause problems for humans. The Carolina parakeet, a beautiful green, red, and yellow bird endemic to the southern United States, was extinct by 1920, exterminated by farmers because it ate fruit and grain crops.

Table 10.1

TABLE 10.1 Advantages and Disadvantages of Several Major Energy Sources climate Source Geographic Distribution Portability Versatility Worst‐Case Event Day‐to‐day Pollution (Not Climate Change) Climate Change Potential Scale Reliability Nuclear fission Uranium found in a limited number of places Fuel can be moved, but must be used in a fixed location Used to generate electricity Reactor failure and release unlikely, but could cause thousands of deaths and long‐term contamination Typically low Low after construction Large power plants only Can run all the time Solar photovoltaic Widely available Limited Used to generate electricity Low risk Low Very low Flexible Daily and seasonal variability Hydropower Found in a limited number of places Cannot be moved Mostly used to generate electricity, but sometimes for mechanical energy Dam collapse rare, but could cause thousands of deaths Low, but permanent disruption to upstream and downstream ecosystems Low after construction Flexible but depends on location Can run all the time Natural gas Found in a limited number of places Can be piped or trucked; often condensed Can be used for heating, cooking, transportation, and industry Natural gas plant or pipeline explosion unlikely, but could cause hundreds of deaths Lowest of the fossil fuels; can burn cleanly High Flexible Can run all the time Coal Found in a limited number of places Fuel can be moved, but must be used in a fixed location Used to generate electricity, for heating, and in industry Power plant failure could cause some deaths Difficult to burn cleanly; releases sulfur, nitrogen, and soot to air, land, and water Highest Flexible Can run all the time Oil Found in a limited number of countries Highly portable, especially when refined into gasoline, diesel, and other fuels Highly versatile; can be used for heating, cooking, transportation, and industry Refinery accident could cause some deaths Refining can be dirty, and burning gasoline, diesel, and other fuels releases pollutants High Very flexible Can run all the time Wind Available in most countries, but not everywhere in those countries Cannot be moved Mostly used to generate electricity, but sometimes for mechanical energy Low risk Low Low Flexible Seasonal and unpredictable variability Geothermal Available in most countries, but not everywhere in those countries Cannot be moved Used to generate electricity, occasionally for heating Low risk Low Low Usually mid to large scale Can run all the time Energy Consumption Conspicuous differences in per person energy consumption are found from country to country (Figure 10.1). Inhabitants of wealthier countries typically consume much more energy per person than those in poorer countries. Although less than 20% of the world's population lived in highly developed countries in 2017, they used 60% of the commercial energy consumed worldwide.

Payback time

The amount of time required to recover a capital expenditure through the savings from that initial expenditure.

Conserving Water at Home

The average U.S. citizen uses 265 L (70 gal) of water per day at home on indoor uses: approximately 27% to flush toilets, 22% for washing clothes, 19% for baths and showers, 16% used from faucets, and 14% lost through leaks. As a water user, you have a responsibility to use water carefully and wisely. The cumulative effect of many people practicing personal water conservation measures has a significant impact on overall water consumption. You can adopt these measures yourself. The bathroom is a good place to start because most of the water used in an average home is for showers, baths, and flushing toilets (see cartoon): 1. Install water‐saving showerheads and faucets to cut down significantly on water flow. Low‐flow showerheads, for example, reduce water flow from 5 to 9 gal per minute to 2.5 gal per minute. Replacing one old showerhead brings a home $30 to $50 each year in water and energy savings. You can also save water by replacing washers on leaky faucets. 2. Install a low‐flush toilet or use a water displacement device in the tank of a conventional toilet. Low‐flush toilets require only 2 gal or less per flush, compared with 5 to 9 gal for conventional toilets. To save water with a conventional toilet, fill an empty plastic bottle with water and place it in the tank to displace some of the water. Don't put the bottle where it will interfere with the flushing mechanism; don't add bricks to the tank, because they dissolve over time and can cause costly plumbing repairs. 3. An important way to conserve water at home is to fix leaky fixtures. For example, a toilet with a silent leak could waste 30 to 50 gal of water each day. You can test for a silent leak by putting food coloring in the reserve tank. If the color shows up in the toilet bowl before you flush, you have a leak. 4. If you are in the market for a washing machine, high‐efficiency washing machines require less water than traditional models and also require less energy and less detergent. Always adjust the water level to match the size of the load. 5. Modify your personal habits to conserve water. Take short showers, no longer than 10 minutes. Avoid leaving the faucet running. Allowing the faucet to run while shaving consumes an average of 20 gal of water; you will use only 1 gal if you simply fill the basin with water or run water only to rinse your razor. You may save as much as 10 gal of water a day by wetting your toothbrush and then turning off the tap while you brush your teeth, as opposed to running the water the entire time. 6. Surprisingly, you will save water by using a dishwasher, which typically consumes about 12 gal per run, instead of washing dishes by hand with the tap running—but only if you run a full load of dishes. That 12 gal of water is used regardless of whether the dishwasher is full or half‐empty. 7. If you have a yard, evaluate your landscaping. Use native or drought‐resistant plants suitable for your region, and employ conservation methods such as replacing lawns with rocks or synthetic grass. Remember that wasting water costs you money. Conserving water at home reduces your water bill and heating bill: If you are using less hot water, you are using less energy to heat that water.

Saving energy at home

The average household spends about $3500 each year on utility bills. This cost can be reduced considerably by investments in energy‐efficient technologies. When buying a new home, a smart consumer should demand energy efficiency. Although a more energy‐efficient house might cost more, depending on the technologies employed, the improvements usually pay for themselves in two or three years. Any time spent in the home after the payback period means substantial energy savings. Energy efficiency has become an essential element of design codes nationwide and will almost certainly be an important part of future home designs. Some energy‐saving improvements, such as thicker wall insulation, are easier to install while the home is being built. Other improvements can be made in older homes to enhance energy efficiency and, as a result, reduce the cost of heating the homes. Examples include installing thicker attic insulation, installing storm windows and doors, caulking cracks around windows and doors, replacing inefficient appliances and furnaces, and adding heat pumps. Many of the same improvements provide energy savings when a home is air‐conditioned. Additional cooling efficiency is achieved by insulating the air conditioner ducts, especially in the attic; buying an energy‐efficient air conditioner; and shading the south and west sides of a house with deciduous trees. Window shades and awnings on south‐ and west‐facing windows reduce the heat a building gains from its environment. Ceiling fans can supplement air conditioners by making a room feel comfortable at a higher thermostat setting. Make sure your ceiling fan is set to draw warm air toward the ceiling in the summer, and reverse this setting in the winter. Other energy savings in the home include the following (see figure): Replace incandescent bulbs with more energy‐efficient light bulbs. Install a programmable thermostat, which cuts heating and air‐conditioning costs up to 33%. Lower the temperature setting on water heaters to 140°F (with a dishwasher) or 120°F (without). Install low‐flow shower heads and faucet aerators to reduce the amount of hot water used. Eliminate energy "vampires," or appliances that draw electricity even when they're not in use. (A study by researchers at Cornell University suggests that American households waste $3 billion each year on electricity vampires).

Extinction

The death of the last individual of a species.

Habitat fragmentation

The division of habitats that formerly occupied large, unbroken areas into smaller, isolated areas by roads, fields, cities, and other land‐transforming activities. Also called fragmentation.

International Perspective on Minerals

The economies of industrialized countries require the extraction and processing of large amounts of minerals to make products. Most of these highly developed countries rely on the mineral deposits in developing countries, having long since exhausted their own supplies. As developing countries become more industrialized, their own mineral requirements increase correspondingly, adding further pressure to a nonrenewable resource. In fact, humans have consumed more minerals since World War II than were consumed in the previous 5000 years, from the beginning of the Bronze Age to the middle of the 20th century (Interactive Figure 15.8). Interactive Figure 15.8 Annual U.S. use of raw nonfuel minerals, 1900-2010. Source: USGS National Minerals Information Center (2012) Mining in the United States has clearly caused many serious environmental problems. The problems in developing countries that rely on mining for a significant part of their economies are as great as or greater than those faced by highly developed countries. The governments in developing countries lack the financial resources and infrastructure to deal with acid mine drainage and other serious environmental problems caused by hardrock mining. To complicate the issue, foreign companies often have significant mining interests in developing countries. For example, France, Germany, Great Britain, Japan, Russia, Spain, and the United States have been involved at various times during the past two centuries in mining (some would say exploiting) ores containing tin, zinc, copper, and lead in Bolivia. The mining district of Bolivia faces catastrophic environmental degradation resulting from decades of mining abuse. Worldwide Mineral Production and Consumption At one time, most of the highly developed countries had rich resource bases, including abundant mineral deposits that enabled them to industrialize. In the process of industrialization, they largely depleted their domestic reserves of minerals and as a result must increasingly turn to developing countries. This is particularly true for European countries, Japan, and, to a lesser extent, the United States. The level of mineral consumption varies widely between highly developed and developing countries. The United States and Canada, which have not quite 5% of the world's population, consume about 25% of many of the world's metals. It is too simplistic, however, to divide the world into two groups, the mineral consumers (highly developed countries) and the mineral producers (developing countries). Although many developing countries do lack any significant mineral deposits, the world's 10 most resource‐rich nations—in terms of value of metal and ore reserves—are not all the wealthiest: South Africa, Russia, Australia, Canada, Brazil, China, Chile, the United States, Ukraine, and Peru. Mineral production and consumption in China are increasing dramatically as China industrializes. For example, in 2015 China produced about 55% of the world's primary aluminum (aluminum obtained from ores, not from recycling). China also consumed most of this aluminum, making it both the world's largest producer and biggest consumer of primary aluminum. Because industrialization increases the demand for minerals, developing countries that at one time met their mineral needs with domestic supplies become increasingly reliant on foreign supplies as economic development occurs. South Korea is one such nation. During the 1950s it exported iron, copper, and other minerals. South Korea has experienced dramatic economic growth from the 1960s to the present and, as a result, must now import iron and copper to meet its needs. Mineral Distribution Versus Consumption The metallic element chromium provides a useful example of global versus national distribution and consumption. Chromium is used to make vivid red, orange, yellow, and green pigments for paints; chrome plate; and, combined with other metals, certain types of hard steel. Chromium has no known substitute for many of its important applications, including jet engine parts. Industrialized nations that lack significant chromium deposits, such as the United States, must import essentially all of their chromium. South Africa is one of only a few countries with significant deposits of chromium. Zimbabwe and Turkey also export chromium. Although world reserves of chromium are adequate for the immediate future, the United States and several other industrialized countries are utterly dependent on a few countries for their chromium supplies. Many industrialized nations have stockpiled strategically important minerals to reduce their dependence on potentially unstable suppliers. The United States and others have stockpiles of strategic minerals such as titanium, tin, manganese, chromium, platinum, and cobalt, mainly because these metals are critically important to industry and defense; in the United States, stockpiles have been decreasing since 1994. For some years, China has been stockpiling rare earth metals, now possessing about 95% of their global stocks. There are 17 rare earth metals, including dysprosium and terbium, which are important in high‐technology applications like hybrid‐car batteries, wind turbines, and laser‐guided missiles. In recent years, China's stockpiling of these rare earth metals and its tariffs on their export caused market prices to skyrocket. By 2015, however, a glut of suppliers and the forced removal of tariffs triggered steep drops in the minerals' value. Despite their name, rare earth metals are not necessarily rare; the designation refers to the fact that these minerals are rarely found in their pure form. Evaluating Our Mineral Supplies Will we run out of supplies of important minerals? To address this question, we must first examine how large the global supply of various mineral reserves and mineral resources is. Mineral reserves are currently profitable to extract, whereas mineral resources are potential resources that may be profitable to extract in the future. The combination of a mineral's reserves and resources is its total resources or world reserve base Estimates of mineral reserves and resources fluctuate with economic, technological, and political changes. A mineral's availability can be affected by conflict in regions where it is found. If the price of a mineral on the world market falls, certain borderline mineral reserves may slip into the mineral resource category; increasing prices may restore them to the mineral reserve category. When new technological methods decrease the cost of extracting ores, deposits ranked in the mineral resource category are reclassified as mineral reserves. If the political situation in a country becomes so unstable that mineral reserves cannot be mined, they are reclassified as mineral resources; a later shift toward political stability may cause the minerals to be placed on the mineral reserve list again. It is extremely difficult to forecast future mineral supplies. In the 1970s, projections of escalating demand and impending shortages of many important minerals were commonplace. There are three reasons that none of these shortages actually materialized. First, new discoveries of major deposits occurred in recent decades—iron and aluminum deposits in Brazil and Australia, for example. Second, plastics, synthetic polymers, ceramics, and other materials replaced metals in many products. Third, a global economic slump resulted in a lower consumption of minerals. However, it is always possible that changes in the world economic situation—such as the rapid economic development of China—will contribute to future mineral shortages. Economic factors aside, the prediction of future mineral needs is difficult because it is impossible to know when or if there will be new discoveries of mineral reserves or replacements for minerals (such as plastics). It is impossible to know when or if new technological developments will make it economically feasible to extract minerals from low‐grade ores. With these reservations in mind, most experts currently think mineral supplies, both metallic and nonmetallic, will be adequate during the 21st century. However, several important minerals—mercury, tungsten, and tin, for example—may become increasingly scarce during that period. Another reasonable projection is that the prices of even relatively plentiful minerals, such as iron and aluminum, will increase during your lifetime. The eventual depletion of large, rich, and easily accessible deposits of these metals means that we will have to mine and refine low‐grade ores, which will be more expensive.

Mass extinction

The extinction of numerous species during a relatively short period of geologic time.

Subsurface mining

The extraction of mineral and energy resources from deep underground deposits

Surface mining

The extraction of mineral and energy resources near Earth's surface by first removing the soil, subsoil, and overlying rock strata (i.e., the overburden).

Medicinal, agricultural, and industrial importance of organisms

The genetic resources of organisms are vitally important to the pharmaceutical industry, which incorporates into its medicines many hundreds of chemicals derived from organisms. From extracts of cherry and horehound for cough medicines to certain ingredients of periwinkle and mayapple for cancer therapy, derivatives of plants play important roles in the treatment of illness and disease (Figure 16.3). Many of the natural products taken directly from marine organisms, such as tunicates, red algae, mollusks, corals, and sponges, are promising anticancer or antiviral drugs. The AIDS (acquired immune deficiency syndrome) drug AZT (azidothymidine), for example, is a synthetic derivative of a compound from a sponge. The 20 best‐selling prescription drugs in the United States are either natural products, natural products that are slightly modified chemically, or synthetic drugs whose chemical structures were originally obtained from organisms. p0461 FIGURE 16.3 Medicinal value of the rosy periwinkle The rosy periwinkle (Catharanthus roseus) produces chemicals effective against certain cancers. Drugs (e.g., Vincristine) from the rosy periwinkle have increased the chance of surviving childhood leukemia from about 5% to more than 95%. The agricultural importance of plants and animals is indisputable, because we must eat to survive. However, the kinds of foods we eat are limited compared with the total number of edible species. Many species that are nutritionally superior to our common foods probably exist. Winged beans are a tropical legume from Southeast Asia and Papua New Guinea. Because the seeds of the winged bean contain large quantities of protein and oil, they may be the tropical equivalent of soybeans. Almost all parts of the plant are edible, from the young, green fruits to the starchy storage roots. Modern industrial technology depends on a broad range of products from organisms. Plants supply oils and lubricants, perfumes and fragrances, dyes, paper, lumber, waxes, rubber and other elastic latexes, resins, poisons, cork, and fibers. Animals provide wool, silk, fur, leather, lubricants, waxes, and transportation, and they are important in medical research. Insects secrete a large assortment of chemicals that represent a wealth of potential products. Certain beetles produce steroids with birth‐control potential, fireflies produce a compound that may be useful in treating viral infections, and some fly species show promise as a source of new antibiotics. Centipedes secrete a fungicide that could help protect crops. Because biologists estimate that perhaps 90% of all insects have not yet been identified, insects represent an important potential biological resource.

Ecosystem services and species richness

The living world is a complex system. Each ecosystem is composed of many separate parts, the functions of which are organized and integrated to maintain the ecosystem's overall performance. The activities of all organisms are interrelated; we are linked and dependent on one another and on the physical environment, often in subtle ways. When one species declines, other species linked to it may decline or increase in number. Consider, for example, the role of alligators in the environment (Figure 16.2). The American alligator helps maintain populations of smaller fishes by eating the gar, a fish that preys on them. Alligators dig underwater holes that other aquatic organisms use during droughts, when the water level is low. The nest mounds they build are enlarged each year and eventually form small islands colonized by trees and other plants. In turn, the trees on these islands support heron and egret populations. The alligator habitat is maintained in part by underwater "gator trails," which help clear out aquatic vegetation that might eventually form a marsh. p0460 FIGURE 16.2 Role of alligators in the environment The American alligator (Alligator mississippiensis) plays an integral, but often subtle, role in its natural ecosystem. Photographed at Cypress Flats, Louisiana. Bacteria, protists, animals, fungi, and plants are instrumental in many environmental processes essential to human existence. Forests are not just a potential source of lumber; forests provide watersheds from which we obtain fresh water, control the number and severity of local floods, and reduce soil erosion. (See the Chapter 14 opener for a vivid example of the consequences of erosion, a landslide in Washington State.) Many flowering plant species depend on insects to transfer pollen for reproduction. Animals, fungi, bacteria, and protists help keep the populations of various species in check so that the numbers of one species do not increase enough to damage the stability of the entire ecosystem. Soil dwellers, from earthworms to bacteria, develop and maintain soil fertility for plants. Bacteria and fungi perform the crucial task of decomposition, which allows nutrients to cycle in the ecosystem. All these processes are ecosystem services, important environmental benefits that ecosystems provide to people, such as clean air to breathe, clean water to drink, and fertile soil in which to grow crops. Ecosystem services maintain the living world, including human societies, and we are completely dependent on them. (Table 5.1 summarizes some important ecosystem services.) The loss of only a few species from an ecosystem endangers the other organisms in unpredictable ways. Just as a car runs less smoothly if some parts are missing, the removal of species from a community makes an ecosystem run less smoothly. If enough species are removed, the entire ecosystem will change. Species richness within an ecosystem provides the ecosystem with resilience, that is, the ability to recover from environmental changes or disasters (see the discussion of species richness and community stability in Chapter 5).

Biodiversity

The number, variety, and variability of Earth's organisms; consists of three components: genetic diversity, species richness, and ecosystem diversity.

Aquifers

Underground caverns and porous layers of sand, gravel, or rock in which groundwater is stored.

Smart growth

Urban planning and transportation strategy that mixes land uses.

Gray water

Water that has already been used for a relatively nonpolluting purpose, such as showers, dishwashing, and laundry; gray water is not potable, but it can be reused for toilets, plants, or car washing.

Restoration of Mining Lands

When a mine is no longer profitable, the land can be reclaimed, or restored to a seminatural condition, as has been done to most of the Copper Basin in Tennessee. The goals of reclamation include preventing further degradation and erosion of the land, eliminating or neutralizing local sources of toxic pollutants, and making the land productive for purposes other than mining. Restoration also makes such areas visually attractive (Figure 15.7). p0406 FIGURE 15.7 Reclaimed copper‐mined land This reclaimed and remediated land is a formerly active portion of the Highland Valley copper and molybdenum mine, which still maintains operations near Logan Lake, British Columbia. A great deal of research is available on techniques of restoring lands degraded by mining, called derelict lands. Restoration involves filling in and grading the derelict land to its natural contours, then planting vegetation to hold the soil in place. The establishment of plant cover is not as simple as throwing a few seeds on the ground. Often the topsoil is completely gone or contains toxic levels of metals, so special types of plants that tolerate such a challenging environment must be used. According to experts, the main limitation on the restoration of derelict lands is not a lack of knowledge but a lack of funding. The Surface Mining Control and Reclamation Act of 1977 requires reclamation of areas that were surface‐mined for coal (see Chapter 11). However, no federal law is in place to require restoration of derelict lands produced by other kinds of mines. Recall from the chapter introduction that the General Mining Law makes no provision for reclamation. Creative Approaches to Cleaning Up Mining Areas Although wetlands are widely known to provide beneficial wildlife habitats, few people realize the potential of wetlands to help clean up former mining lands. Creating and maintaining wetlands is expensive, although it is cost effective when compared to using lime to reduce the water's acidity. Wetlands tend to trap sediments and pollutants that enter them from upstream areas, so the quality of water resources located downstream from wetlands is improved. Although a single wetland provides these benefits, a series of wetlands constructed in the affected drainage basin is much more effective. Consider the area around Butte, Montana, where copper was mined for 100 years. This area is one of the largest Superfund sites in the United States. Its soil and water are contaminated with copper, zinc, nickel, cadmium, and arsenic. Many cleanup technologies have been developed and tested in Butte, including the design and construction of artificial wetlands. As contaminated water seeps into the wetland, bacteria consume the sulfur draining from the mines, making the water less acidic. As the water becomes less acidic, zinc and copper precipitate (settle out of solution) and enter the sediments. Constructed wetlands typically take 50 to 100 years to neutralize the acid enough for aquatic life to return to rivers and streams downstream from acid mine drainage. This time estimate is based on observations of more than 800 wetland systems constructed at coal mining sites in Appalachia, the region in the eastern United States that encompasses the central and southern Appalachian Mountains. Scientists are also using plants to remove heavy metals from former mining lands. Phytoremediation is the use of specific plants to absorb and accumulate toxic materials such as nickel from the soil. Although most plants do not tolerate soils rich in nickel, some plants, such as twist flower (Streptanthus polygaloides), thrive on it. This species is a hyperaccumulator, a plant that absorbs high quantities of a metal and stores it in its cells. The plants can be grown on nickel‐contaminated land, harvested, and hauled to a hazardous waste site for disposal. Alternatively, the plants are burned, and nickel is obtained from the ashes. Phytoremediation has great potential to decontaminate mining and other hazardous waste sites and to extract valuable metals from soil in an environmentally benign way. (See Chapter 23 for further discussion of phytoremediation.)

Watershed

a drainage basin An ecosystem where all water runoff drains into a single body of water

Food deserts

a neighborhood in which low-quality , processed foods are far easier to acquire than nutritionally dense, fresh foods

Brownfields

an urban area whose redevelopment is hindered due to possible contamination

Megacities

cities with more than 10 million people

Renewable energy

energy from a source that is not depleted when used, such as wind or solar power.

Background extinction

normal extinction of various species as a result of changes in local environmental conditions The continuous, low‐level extinction of species that has occurred throughout much of the history of life.

Biomass energy

renewable energy derived from burning organic materials such as wood and alcoholBiomass, one of the oldest fuels known to humans, consists of such materials as fast‐growing plant and algal crops, crop wastes, sawdust and wood chips, animal wastes, and wood (Figure 12.8). Biomass contains chemical energy that comes from the sun's radiant energy, which photosynthetic organisms use to form organic molecules. Biomass is a renewable form of energy when used no faster than it is produced; deforestation and desertification can result when biomass is overused (see Chapter 17). Biomass cannot replace fossil fuels. The entire photosynthesis production of the continental United States amounts to only half of our current energy use—and that would mean devoting it to no other uses, including food, paper, and construction materials.

Table 15.1

some important minerals and their uses Aluminum: aircraft, motor vehicles, packaging (cans, foil) water treatment Chromium: chrome plate, dyes, and paints, steel alloys (cutlery) Cobalt: corrosion and wear resistant alloys, pigments (cobalt blue) Gold: jewelry, money, electronics, aerospace, restorative dentistry Iron: steel (alloy of alloy) buildings and machinery Magnesium: beverage cans, electronic devices, firecrackers, flames Mercury: industrial chemicals, electric and electric applications, batteries Molybdenum: high temperature alloys for aircraft, industrial motors Nickel: coins, metal plating, alloys with various uses Potassium: fertilizers, photography Silver: jewelry, silverware, photography, electronics Titanium: alloy in steel and other industrial, alloys, pigment in paints and plastics Zinc: Galvanizing steel, alloys (brass) anode in alkaline batteries Gysum: drywall, plaster of Paris Soil conditioner Silicon: electronic devices, semiconductors, natural stone, glass, concrete Sulfur: Industrial chemicals, insecticides, gunpowder, vulcanized tires

Urbanization

the process in which people increasingly move from rural areas to densely populated cities