Chapter 7 Water How Do We Use It and Affect Its Quality PDF

CHAPTER 7 Water: How Do We Use It and Affect Its Quality? Copyright © 2023 W. W. Norton & Company, Inc.  Chapter 7 Outline 7.1 Where on Earth Is All the Water? 7.2 How Does Fresh Water Support Life? 7.3 How Do Humans Impact Fresh Water? 7.4 Can We Improve Access to Fresh Wate...

CHAPTER 7 Water: How Do We Use It and Affect Its Quality? Copyright © 2023 W. W. Norton & Company, Inc.  Chapter 7 Outline 7.1 Where on Earth Is All the Water? 7.2 How Does Fresh Water Support Life? 7.3 How Do Humans Impact Fresh Water? 7.4 Can We Improve Access to Fresh Water? 7.5 How Do We Keep Fresh Water Clean? 7.6 Why Is Frozen Water Important? 7.7 How Does the Ocean Support Life? 7.8 How Can Humans Impact the Ocean? 7.9 What Can I Do?  Chapter Objectives: This chapter will help you… To describe how water on Earth moves among all three phases of matter: solid, liquid, and gas. To understand how water cycles between the atmosphere, ocean, snow and ice pack, groundwater, and surface water. To understand that groundwater and surface water are our sources of liquid fresh water and that these two systems are linked. To identify ways that human activities impact both the availability and quality of fresh water. To recognize that most of Earth’s freshwater is frozen in permafrost, ‫ الترب(ة الص(قيعية‬glaciers ‫األنه(ار الجليدي(ة‬, and sea ice. ‫الجلي(د‬ ‫البحري‬ To describe the diversity of life in the oceans, and how humans impact it.  Value of Water (1 of 3) The UN estimates that approximately 3.5 million people die each year from contaminated water, and that one-fifth of the world’s population suffers from water scarcity. Droughts and shortages are projected to become more frequent, which will make water scarcity more common. Unavailable freshwater is held in salt water, frozen glaciers, suspended in the air, and held in the bodies of living organisms.  Value of Water (3 of 3) Embedded water is a concept that accounts for the water that is used to produce goods we consume. ‫المي اه المدمج ة" ه و المص طلح ال ذي يطل ق على المي اه‬ ‫المخفية المستخدمة إلنتاج األشياء التي نعتبرها أمرا مفروغا‬ ‫منه‬. In 2015, the United States' industrial water use was about 57 billion liters per day. Pollution from human activities and climate change contribute to the decline in freshwater biodiversity and water supply. Middle Eastern countries with inadequate freshwater resources, meet 60% of their water needs with desalinated ocean water.  Embedded Water ‘Embedded Water’ is the term for the hidden water that’s used to produce the things we take for granted. For example, it takes around 2,700 litres of water to produce one cotton t-shirt – that’s enough for one person to drink for 900 days! What we mean is that it takes 2,700 litres to grow the cotton and physically construct the t- shirt – that’s the ‘Embedded Water’ cost that we rarely think about.  7.1 Where on Earth Is All the Water? (1 of 4) Water is constantly moving in and out of cells, oceans, the atmosphere, surface water, groundwater, frozen ice, and snow. Places where water spends time are called reservoirs. Reservoirs make up the Earth's hydrosphere: a closed system that recycles water molecules again and again between reservoirs. The amount of time a molecule spends in a particular reservoir is known as residence time.  Where on Earth Is All the Water? (2 of 4) The atmosphere holds about 0.001% of Earth's total water supply, with an average residence time of 10 days. The ocean holds about 97% of Earth's water supply, with an average residence time of 3,000 years. Almost 80% of Earth's fresh water is frozen. Groundwater is the largest reservoir of liquid fresh water and feeds into the oceans, lakes, and rivers.  Where on Earth Is All the Water? (3 of 4) ~500,000 cubic kilometers of water falls from the atmosphere per year. 75% of global precipitation falls into oceans. When precipitation falls to the ground, some water drains down and accumulates in subsurface areas of rocks or sediments forming an aquifer. ‫طبقة المياه الجوفية‬ The average residence time of water in an aquifer is hundreds or thousands of years.  Where on Earth Is All the Water? (4 of 4) The top of the groundwater reservoir is called the water table, which marks the boundary between the saturated and unsaturated zones.  Take-Home Message Water cycles between Earth's major reservoirs in the atmosphere, in the ocean, on land, and beneath Earth's surface. Most of Earth's water is held in the ocean as salt water. All significant supplies of liquid fresh water on Earth exist as surface water or groundwater. The largest reservoir of fresh water on the  7.2 How Does Fresh Water Support Life? Groundwater-dependent ecosystems are communities of organisms that require groundwater to meet at least some of their water needs. Aboveground, groundwater may seep to the surface, supplying fresh water during dry periods to plants and animals.  Lakes and Ponds (1 of 3) Freshwater sources, such as rivers, streams, lakes, and wetlands, are called surface water. Lakes and ponds form when water fills areas cut out by slowly retreating glaciers (masses of ice that flow over land surfaces), by volcanic eruptions.  Rivers and Streams Flowing water systems, such as rivers and streams, are lotic ecosystems, which have different habitats created by variations in their flow. Lentic ‫ مي((اه س((اكنة‬and lotic ‫ مي((اه جاري((ة‬ecosystems are two types of freshwater ecosystems that differ primarily in their water flow characteristics: Lotic Ecosystems: Flowing water Definition: Lotic ecosystems refer to flowing water bodies, such as rivers, streams, and creeks. Lentic Ecosystems. Standing water. Definition: Lentic ecosystems refer to static or slow-moving water bodies, such as lakes, ponds, and wetlands.  Lotic water = Flowing water ‫المياة المتحركة‬ Lentic Ecosystems. Standing water  Life in Wetlands and Estuaries Wetlands ‫األراضي الرطبة‬ are areas where the ground is seasonally or permanently saturated with water. Wetlands form along the edges of lakes and streams, or in land depressions that fill with precipitation or groundwater. Forested wetlands are called swamps. Wetlands dominated by grasses and cattails are called marshes ‫أهوار‬. Estuaries ‫ مصبات األنهار‬are wetlands where fresh water  Wetlands Cattai Marshes ls Estuaries ‫مصبات األنهار‬ Forested wetlands are called swamps  Take-Home Message Freshwater ecosystems include those that are groundwater dependent, as well as those in lakes, ponds, rivers, streams, wetlands, and estuaries. In lentic ecosystems ‫ المياة الساكنة‬, zones of life are defined by distance from shore and depth in the water. In lotic ecosystems ‫ المياة المتحركة‬, zones of life are defined by the speed of water flowing through them. Wetlands are areas where the ground is seasonally or permanently saturated with water and include some of the most biologically diverse areas on Earth.  7.3 How Do Humans Impact Fresh Water? Humans impact freshwater systems in two broad ways: by withdrawing or diverting water, and by adding pollutants. Humans use more freshwater for crop irrigation than for any other purpose.  Increased Withdrawals from Groundwater Systems (1 of 2) Advances in technology have caused the global use of groundwater to expand 10- fold since 1950. Groundwater is considered a renewable resource, but the replacement, or recharge, time is over 10,000 years. Human use far exceeds resupply. Aquifers sealed off by surrounding rock can no longer recharge from precipitation and contain “fossil water” with a residence of millions of years. These aquifers are non-renewable, so withdrawals from them are considered water mining.  Increased Withdrawals from Groundwater Systems (2 of 2) Groundwater depletion shrinks rivers and wetlands. Depletion can also lead to saltwater intrusion from the ocean, contaminating freshwater wells. Excessive groundwater withdrawals can also cause subsidence ‫ هبوط فى (االرض‬, a sinking or collapse of the ground surface. Subsidence permanently reduces the aquifer’s ability to store water.  Disruptions to Surface Water Systems (1 of 3) Impervious surfaces ‫األسطح غير المنفذة‬, such as pavement and rooftops, divert water to storm drains and nearby waterways instead of to soil surfaces. Water runoff ‫ جري(ان المي(اه‬increases the peak flows of rivers, causing flooding, erosion of the riverbanks, and the removal of fish eggs from streambeds. Runoff prevents water from draining into the soil, reducing groundwater recharge. Water  Disruptions to Surface Water Systems (2 of 3) Dams, reservoirs, canals, and pipelines divert water from where it naturally flows. Dams cause increased rates of freshwater evaporation, decreased water flow, and act as barriers to migrating fish. Dams also prevent nutrient-rich sediment from traveling downstream, forcing it to accumulate in the reservoir.  Disruptions to Surface Water Systems (3 of 3) Around 2000 BCE, the Egyptians invented the first canal systems to use water from the Nile River for irrigation. Man-made canals and channels contribute to the loss of wetlands by preventing seasonal flooding and lowering the water table. Negative effeact Diverting surface water upstream reduces the amount of available water downstream.  Water Pollution (1 of 3) A point source of freshwater pollution is a clearly identifiable source of contamination, such as a drainpipe, channel, ditch, or well. A nonpoint source is a broad or diffuse source of pollution that is less easily identified, such as agriculture, residential runoff, or airborne pollutants from industry. The most common type of water pollution is sediment pollution, when large amounts of loose soil are swept into waterways by erosion from agriculture, forestry, and urban development. Sediment pollution causes turbid (cloudy) waters, which reduces light penetration, restricts plant growth, and reduces nutrient levels. What Are the Causes and Effects of Water Pollution? Water pollution Any change in water quality that can harm living organisms or make the water unfit for human uses such as irrigation and recreation. It involves contamination by one or more: Chemicals. Excessive heat. Types of sources. Point sources: ‫التلوث من مصدر ثابت‬ Discharge pollutants into bodies of surface water at specific locations by means such as drainpipes, ditches, and sewer lines. Non-point sources: ‫التلوث من مصادر غير ثابتة‬ Broad and diffuse areas, rather than specific points, from which pollutants enter bodies of water or air. Agriculture is the biggest nonpoint water pollution source (toxic fertilizer runoff ).  Pollution Comes from a Number of Sources Types of pollution sources: Point-source pollution is easy to identify. This is the pollution that comes from a single place. ‫التلوث من مصدر ثابت‬ Nonpoint source pollution is the pollution that comes from many places, all https:// at once. ‫التلوث من مصادر غير ثابتة‬ education.nationalgeographic.or g/resource/point-source-and- nonpoint-sources-pollution https://www.youtube.com/watch? v=ONmJFucvag0 https://www.youtube.com/watch? v=2WHW3F5qG18 Examples of point sources vs non-point sources  Water Pollution (2 of 3) Biological pollution refers to the presence of disease-causing bacteria, viruses, and protozoa. Biological pollution occurs when water is contaminated by manure, untreated sewage, or food-processing wastes. Chemical pollution can be caused by agriculture, mining, energy production, and fuel leaks. Air pollutants react with water vapor to fall as acid rain, changing the chemistry of lakes and ponds.  Water Pollution (3 of 3) A common chemical pollutant is agricultural fertilizer, which causes eutrophication. Fertilizers increase nutrient availability, causing rapid phytoplankton and algae growth, death and decomposition. The decomposition process consumes the available oxygen, suffocating fish and other oxygen-dependent organisms. Eutrophic Lakes Oligotrophic lakes  Take-Home Message Humans impact freshwater systems by physically disrupting and polluting them. The slow recharge rate of groundwater systems often lag behind the rate of human withdrawals. Surface water withdrawals and diversions also cause ecological harm by diminishing and obstructing stream flows. Water pollutions comes in the form of added chemicals, disease-causing organisms, and/or physical changes. Water pollution can result from agriculture, mining, industry, and biological contaminants like sewage.  7.4 Can We Improve Access to Fresh Water? More than a billion people suffer from water scarcity. Increasing water scarcity will lead to increasing conflicts within and between countries over water access. In some regions of Africa, more than half of the population lacks access to safe drinking water. Some people walk 3 hours or more a day to obtain water. A sustainable development goal of the United Nations is water security, defined as reliable access to safe and affordable water.  Where Does the Water Go? Globally, agriculture uses the largest share of water (70%), followed by industry (20%), and public water supplies for residential use (10%). These uses are considered consumptive because the water is removed and not returned to the same source. The bottled water industry removes billions of gallons a year of water to be shipped around the world.  Water Shortages A water shortage occurs where a large percentage of available water has been withdrawn for human use. A drought is a period of low precipitation and high evaporation rates, which can lead to water shortages. Megadroughts can last decades. Droughts can occur in temperate climates as well as arid, desert environments. Conservation is the first way to manage a water shortage.  Water Conservation Conservation within cities includes landscaping measures, such as not watering lawns and planting drought-tolerant plants. Conservation methods around agriculture include infrastructure improvements, such as repairing pipes and conduits to reduce water waste. New irrigation technology and smart systems release water in small targeted amounts only when needed. Farmers can also switch to crops that require less water. Another effective conservation measure is water recycling, which takes residential water, treats it, then uses it for agriculture, industry, or landscape irrigation.  Water Scarcity (1 of 3) Dams are often built to provide a constant water source, but 25% of the world’s population experiences decreases in water availability because of dams. Privatizing water, where a private company owns and manages the water supply, can lead to high prices and declining water quality. Water privatization has also led to additional water scarcity in regions already suffering severe water shortages.  Water Scarcity (2 of 3) Harvesting rainwater and desalination, removing salt from seawater to create fresh water, are possible solutions to water scarcity. Water-harvesting systems as old as 4,000 years have been discovered in the Middle East. Runoff from rooftops or at ground level is captured and directed through pipes or channels to a catchment, such as a cistern or holding pond. In the arid Marwar region of Rajasthan, India, more than 250 water-harvesting structures serve more than 200,000 people.  Water Scarcity (3 of 3) Many countries in the Middle East use large-scale desalination plants to meet their water needs. Desalination plants use heat to evaporate water (leaving the salt behind) or pumps to run water through membranes that filter out the salt. Both technologies are costly and energy-intensive. The extracted salt must also be disposed of in a way that does not damage the environment. New smaller-scale technologies using solar panels and more efficient filters are making desalination more accessible and affordable.  Take-Home Message Water security requires access to safe and affordable water. Unfortunately, many people around the world live in areas suffering from water scarcity. When rates of outflow exceed rates of inflow, the supply of available water in an area diminishes. Measures to improve access to water can include conservation measures such as water harvesting or converting seawater to fresh water through desalination.  7.5 How Do We Keep Fresh Water Clean? (1 of 3) Globally, 2.5 billion people lack access to sanitary wastewater systems and 1.8 billion people use a source of drinking water that is contaminated with sewage. More than 1 million liters of raw sewage are dumped into India’s Ganges River every minute. Most developed nations use septic tanks or sewage treatment plants to filter and treat wastes and produce clean water. Sewage Treatment Reduces Water Pollution Septic tank systems (most popular method) Wastewater or sewage treatment plants Primary sewage treatment Physical process Secondary sewage treatment Biological process with bacteria Tertiary or advance sewage treatment Special filtering processes Bleaching and disinfection Living machines Uses solar greenhouses and artificial marshes to purify water.  How Do We Keep Fresh Water Clean? (2 of 3) The UN invests more than $10 billion per year to improve water security and sanitation. The Millennium Development Goal to Ensure Environmental Sustainability has provided 2.5 billion people with improved drinking water supplies since 1990. Small-scale water purification technologies include ceramic filters and the solar Watercone, which uses the heat of the sun to kill pathogens, remove particulates, and desalinate seawater. Green roofs can reduce runoff, improving infiltration and uptake by plants.  How Do We Keep Fresh Water Clean? (3 of 3) Regulations are also important for clean water. Nonpoint sources of water pollution are difficult to regulate, but actions can still be taken. Farmers can limit the amount of fertilizers and pesticides they use, and leave vegetated buffer zones around crops to slow surface runoff. Public awareness campaigns about pollution are another important tool.  Take-Home Message Addressing water pollution involves setting and enforcing standards for water quality, investing in and encouraging infrastructure and technology, and establishing policies that promote and preserve water quality.  7.6 Why Is Frozen Water Important? (1 of 3) More than 95% of Earth’s glaciers are found near the poles in Greenland and Antarctica. Earth’s glaciers have been losing mass since the 1970s. If all of Greenland’s ice melted, sea- levels would raise by about 6 meters. If all of Antarctica’s ice melted, sea- levels would raise by about 60 meters. A large input of fresh glacial meltwater will disrupt ocean currents, which are a major influence on global climate.  Why Is Frozen Water Important? (2 of 3) Sea ice is defined as frozen water that covers about 15% of the ocean for at least part of the year. Most sea ice is seasonal. Sea ice impacts global climate through its reflectivity or albedo: by deflecting the Sun’s rays, sea ice has a cooling effect on the ocean water below it. When sea ice melts, the temperature of the ocean increases, but it does not contribute to sea-level rise.  Why Is Frozen Water Important? (3 of 3) The cryosphere also includes permafrost, which is water perpetually frozen in soil or rock. Permafrost can extend as deep as several thousand feet belowground and remain frozen for hundreds of thousands of years. Melting permafrost contributes to sea- level rise. Melting permafrost also releases methane, a greenhouse gas that contributes to the increasing rate of global warming. A thawing permafrost layer can lead to severe impacts on people and the environment. For instance, as ice-filled permafrost thaws, it can turn into a mud slurry that cannot support the weight of the soil and vegetation above it. Infrastructure such as roads, buildings, and pipes could be damaged as permafrost thaws. https://www.civilsdaily.com/burning-issue-tha wing-permafrost-and-its-effects / https://www.youtube.com/watch? v=E4kD9FYXlWk  Take-Home Message Earth’s frozen water makes up the cryosphere, including sea ice, glaciers, seasonal ice and snow, and permafrost. Glacial ice and permafrost are formed from freshwater frozen on land, and sea-level rises when they melt or thaw. Sea ice is formed from ocean water and does not raise the sea-level when it melts.  7.7 How Does the Ocean Support Life? (1 of 3) Oceans contain many different ecosystems that receive varying levels of sunlight. Unique organisms live in the intertidal zone and are adapted to both high and low tide conditions, including star fish, sea anemones, barnacles, burrowing crabs, and species of seaweeds.  How Does the Ocean Support Life? (2 of 3) Just beyond the intertidal zone, the shallow water area just above the continental shelf is called the neritic zone. The neritic zone has plentiful sunlight leading to an abundance of phytoplankton (algae), which provides food for shrimp, jellyfish, snails, and small fish. Tropical coral reefs grow in the neritic zone and support diverse ecosystems by providing protection and structure for algae.  Take-Home Message The ocean contains many types of ecosystems. These ecosystems are zones organized by depth and sunlight penetration, ranging from the intertidal zone on the seashore to the deep open ocean.  7.8 How can Humans Impact the Ocean? Human food and energy production and waste disposal impact the ocean. Since the 1950s, global annual fish catch has increased more than 5 times. Terrestrial food production also affects oceans with fertilizer run-off creating dead zones. The use of fossil fuels affects the ocean with oil spills and the burning greenhouse gases can lead to ocean acidification. Plastic waste can entangle sea life and also breaks down into very small pieces ingested by marine organisms. Some Major Human Impacts on Ocean Life (1 of 2) Some Major Human Impacts on Ocean Life (2 of 2)  Take-Home Message Humans impact ocean life through various forms of pollution, altering water chemistry and temperature, and by overharvesting seafood.  Question 1: Answer When water sinks into the ground and reaches a layer of bedrock or dense clay that it cannot pass through, the water accumulates saturating cracks and pores to form areas called ___________________. A. The hydrosphere. B. Residence time. C. Aquifers (Correct). D. Fresh water. E. Glaciers.  Question 2: Answer Estuaries are wetlands where fresh water meets saltwater. These areas are among the most biologically rich areas on Earth because _________________. A. They provide a supply of fresh water during dry periods. B. Of evapotranspiration. C. Of the absence of light and low-nutrient environment supports stygobites. D. They receive abundant light and nutrient-rich sediments (Correct). E. They have variations in flows ranging from turbulent rapids and riffles to relatively still ponds.  Question 3: Answer Groundwater withdrawals can damage groundwater-dependent ecosystems because subsidence may occur. Subsidence is when _____________________________. A. Groundwater is replaced. B. The ground surface sinks, tilts, or collapses (Correct). C. Water mining is renewable. D. Recharge of groundwater resources occurs. E. Existing pipes and plumbing fixtures release lead into drinking water.  Question 5: Answer Humans use more freshwater for _____________________ than for any other purpose. A. Agricultural irrigation of crops (Correct). B. Cooking and drinking. C. Household use. D. Industrial processes. E. Producing hydrogen fuel.  Credits This concludes the Lecture PowerPoint presentation for Environmental Science and Sustainability, Chapter 7, by David Montgomery and Daniel Sherman For more resources, please visit https://digital.wwnorton.com/environsci2 Copyright © 2023 W. W. Norton & Company, Inc.