Chapter 7 - Summarized (Book) PDF

Water Quality, Accessibility, and Usage Concerns about Water Quality: o 2020 poll by Morning Consult: many Americans rate their water as good, but worry about national water quality. o High-profile contamination crises (Flint, Michigan & Newark, New Je...

Water Quality, Accessibility, and Usage Concerns about Water Quality: o 2020 poll by Morning Consult: many Americans rate their water as good, but worry about national water quality. o High-profile contamination crises (Flint, Michigan & Newark, New Jersey) raised awareness of water safety concerns. Daily Water Usage: o Average American uses 80–100 gallons/day (300–380 liters). o Water is often perceived as abundant, but over 3.5 million deaths/year are linked to contaminated water. o More than 1 billion people suffer from water scarcity globally. Water Scarcity and Droughts Global Water Availability: o Most water is not usable (saltwater, ice, atmospheric water, or in living organisms). Drought Example – Cape Town: o 2015–2018 drought: reservoirs dropped to 25% capacity, leading to strict water rationing. o Residents reduced consumption from 21 gallons/day to under 10 gallons/day. o Climate change expected to make droughts more frequent globally. Future Projections: o In the U.S., climate change and outdated infrastructure may make clean water unaffordable for one-third of households. Water Consumption in Production Embedded Water in Products: o 500 gallons (1,900 L) for 1 pound of pork. o 100 gallons (380 L) for 1 pound of potatoes. o 700 gallons (2,650 L) for 1 gallon of beer. Industrial Water Usage: o In 2015, U.S. industry used 15 billion gallons/day (57 billion L/day).  o Desalination in Israel provides 60% of the country’s water needs. Environmental Impact Aquatic Ecosystems: o Human activities are damaging aquatic ecosystems. o Freshwater systems (rivers, lakes) are declining faster than ocean habitats due to pollution and overuse. Glossary Embedded Water: The water used to produce goods that we consume. Reservoir: A part of Earth where a material (such as water) remains for a period of time; also refers to an artificial water body behind a dam. Hydrosphere: All the places that hold water on Earth, including surface water, groundwater, glaciers, and water in the atmosphere. Residence Time: The time a molecule of a nutrient (like water) spends in a particular reservoir. Aquifer: A subsurface area of rock or sediment where water can accumulate or pass through. Evapotranspiration: The combined water vapor released from Earth's land and water surfaces along with transpiration from plants. 7.1 Where on Earth Is All the Water? Human Water Loss: o Typical person loses 2–3 liters/day through sweating, exhaling, and excreting waste. Water Movement on Earth: o Water shifts in and out of living creatures, oceans, atmosphere, ice, surface water, and groundwater. o Each place where water resides is called a reservoir. o All reservoirs together make up Earth's hydrosphere, a closed system recycling water from one reservoir to another. Atmosphere's Water: o Water in the atmosphere is about 0.001% of Earth's total water. o Residence time for water in the atmosphere is about 10 days.  o Earth's surface receives about 500,000 cubic kilometers of precipitation/year, which is 43 times the volume of Lake Superior. Ocean as the Largest Reservoir: o Oceans hold 97% of Earth's water with a residence time of about 3,000 years. Fresh Water Distribution: o About 80% of Earth's fresh water is frozen in ice and snow. o The largest reservoir of liquid fresh water is in groundwater. o Groundwater forms when precipitation infiltrates the ground and accumulates in aquifers. o Groundwater moves slowly, often less than 1 foot/year, and may have a residence time of hundreds or thousands of years. o A small amount of fresh water is found in lakes, rivers, and streams. Groundwater Formation How Groundwater Forms: o Rainfall infiltrates the ground and accumulates in aquifers. o The water table separates the saturated zone below from the unsaturated zone above. o Rivers, streams, lakes, and ponds may be extensions of the water table. o In arid regions, the water table may lie deep, causing ephemeral streams to flow only intermittently. The Water Cycle Water's Movement: o Water shifts between Earth's major reservoirs: atmosphere, ocean, land, and beneath Earth's surface. o Most of Earth's water is held as salt water in the oceans. o Liquid fresh water is found as surface water or groundwater. o The largest fresh water reservoir is frozen in ice and snow. Transpiration and Evapotranspiration: o Plants release water vapor through transpiration, contributing about 10% of water vapor entering the atmosphere. o The combination of water vapor released from land, water surfaces, and transpiration from plants is called evapotranspiration. Take-Home Message Water cycles between Earth's major reservoirs: atmosphere, ocean, land, and underground. Most of Earth's water is in the ocean as salt water. Liquid fresh water exists as surface water and groundwater, while the largest fresh water reservoir is frozen in ice and snow. 7.2 How Does Fresh Water Support Life? Groundwater-dependent ecosystems: Communities that rely on groundwater for their water needs. Some ecosystems are entirely underground, hosting stygobites—organisms adapted to life in low-light, nutrient-scarce environments. Example: Niphargus aquilex (FIGURE 7.5a), a translucent, eyeless crustacean from underground ecosystems in England. Aboveground ecosystems: Groundwater surfaces as seeps and springs, supporting plant and insect life. In desert areas, they serve as vital water sources for animals like desert bighorn sheep (FIGURE 7.5b). Surface Water Surface water: Includes rivers, streams, lakes, and wetlands. Groundwater plays a key role by supplying fresh water and cooling surface water, creating habitats for fish and other species. Lakes and Ponds Lakes and ponds form in various ways: o Glacial lakes: Formed by glaciers retreating and carving out basins (Great Lakes) (FIGURE 7.6a). o Volcanic lakes: Created when water fills the crater of a collapsed volcano (Crater Lake) (FIGURE 7.6b). o Oxbow lakes: Formed when rivers change course, abandoning old channels (FIGURE 7.6c). These are lentic ecosystems, where the water is relatively still and divided into zones by distance from shore and light penetration (FIGURE 7.7). o Littoral zone: Shallow and near shore, hosting the most diverse life, including rooted plants.  o Pelagic zone: Deeper, with further divisions: ▪ Photic zone: Receives enough light for photosynthesis. ▪ Aphotic zone: Deeper, lacking sufficient light. Rivers and Streams Rivers and streams form from water flowing downhill, carving channels in the landscape. These are lotic ecosystems, characterized by flowing water that creates varied habitats (FIGURE 7.8): o Rapids and riffles: Fast-moving water. o Pools: Slower-moving sections. Food webs: Depend on organic matter (leaves, soil) from adjacent land, microbes, and algae. o Insect larvae: Break down organic matter, passing it to filter feeders (e.g., mussels, worms). o Herbivores: Feed on algae and moss. o Carnivores: Include beetles, crayfish, and fish like trout. Wetlands and Estuaries Wetlands: Found along streams and lakes, where the ground is permanently or seasonally saturated (FIGURE 7.8). o Formed by flooding from rivers, streams, lakes, or precipitation. o Swamps: Forested wetlands near rivers. o Marshes: Dominated by grasses and cattails. Wetlands fed by groundwater often accumulate organic matter. Freshwater Ecosystems and Human Impact Freshwater Ecosystems Freshwater systems include lakes, ponds, rivers, streams, wetlands, and estuaries. Wetlands are biologically diverse and include bogs, marshes, and swamps, providing habitats for plants, birds, amphibians, reptiles, and mammals.  Estuaries (where freshwater meets saltwater) are highly productive environments due to nutrient-rich sediment, with salt marshes and mangrove swamps supporting diverse plant and animal life. Human Impact on Fresh Water Flint Water Crisis: The switch to a more corrosive water source in Flint, Michigan, led to lead contamination, highlighting the importance of water treatment and the risks of poor management. Groundwater Withdrawals: Human activities have led to excessive groundwater use, especially in large aquifers like the Ogallala Aquifer. This water is being depleted faster than it can naturally recharge, threatening long-term sustainability. Consequences of Groundwater Depletion Ecosystem Damage: Groundwater-dependent ecosystems, such as wetlands and rivers, suffer from reduced water levels, harming native species. Subsidence: Over-pumping leads to land collapse (subsidence), permanently reducing the capacity of aquifers to store water. Saltwater Intrusion: In coastal areas, overuse of groundwater allows saltwater to infiltrate freshwater supplies, contaminating wells. Human Impact on Freshwater Systems Saltwater Intrusion and Subsidence Saltwater Intrusion: Overpumping of groundwater lowers the water table, allowing salt water to seep into freshwater aquifers, contaminating wells. Subsidence: Excessive groundwater pumping causes land to sink, as demonstrated in California’s San Joaquin Valley, where the ground has subsided by more than 7 feet over 48 years. Disruptions to Surface Water Systems Human-made surfaces like roads and parking lots increase runoff during storms, reducing groundwater recharge and causing flooding in rivers. Water Diversion Technologies: Dams, reservoirs, and canals (like California's State Water Project) divert water for human use but can increase evaporation and prevent fish migration. River Channelization: Straightening rivers disrupts ecosystems, as seen in Florida's Kissimmee River, where channelization dried up 50,000 acres of wetlands. Impact of Surface Water Diversions Dams block sediment movement, depriving ecosystems downstream of nutrients. Water diversion in places like the Colorado River’s estuarine habitats and Australia's Macquarie Marshes has reduced wetland areas by over 50%. Water Pollution Point-Source Pollution: Pollution from a single identifiable source, like drainpipes. Nonpoint-Source Pollution: Diffuse pollution, such as agricultural runoff and airborne contaminants. Sediment Pollution: The most common type, affecting water clarity and harming aquatic life. Chemical Pollution: Agriculture (eutrophication) and energy production (lead, salts, acid rain) significantly degrade water quality. Lead Contamination and Environmental Justice Lead service lines in the U.S. still expose 10 million homes to contamination. Lower-income households are less likely to afford pipe replacement, prompting calls for federal programs to cover costs, as seen in Washington, D.C. Agricultural and Energy Industry Impacts Agriculture increases salt concentrations in freshwater systems, disrupting water chemistry. Energy industries contribute to chemical pollution, including vehicle leaks and acid rain from coal plants. Biological Pollution Runoff contaminated with manure or untreated sewage carries microorganisms that cause diseases like cholera, leading to 2 million deaths annually worldwide. Take-Home Message Humans disrupt freshwater systems through physical alterations and pollution, with groundwater systems being particularly vulnerable due to their slow recharge rate. Save Money and Reduce Waste  Bottled water is about 2,000 times more expensive than tap water. Tap water is a better choice to save money and reduce plastic waste. You can check the quality of your tap water through the EPA’s Consumer Confidence Report (https://www.epa.gov/ccr). Where Does the Water Go? Water supply is influenced by surface water, groundwater, and rates of precipitation, evaporation, and transpiration. Human use often moves water far from its source, with agriculture using 70%, industry 20%, and public water supplies 10%. These are consumptive uses, meaning water is not returned to its source, and a portion is lost through evaporation or embedded in products. Bottled water consumption in the US reached over 14.4 billion gallons in 2019, surpassing soda consumption. Water Shortages In 2015, California ordered a 25% reduction in water use due to a severe drought, the first in its history. Droughts can occur in unexpected places, like southern Florida, and lead to serious water shortages. California and much of the western US experienced a megadrought in 2021, with rising populations, heavy groundwater use, and higher temperatures contributing to frequent shortages. Conservation efforts, like using less water, are essential to managing these problems. Water Conservation Cape Town reduced water loss by fixing leaky pipes. California set water conservation goals, using social media, outreach campaigns, and door-to-door visits to high water users. Landscaping changes, like reducing lawn watering and planting drought-tolerant plants, had the biggest impact. Fines were imposed on water districts and consumers not meeting conservation targets. Agricultural Water Conservation Agriculture consumes the most water globally.  In California, 80% of human water use is for irrigating 9 million acres of farmland. Traditional irrigation wastes nearly 50% of water through evaporation and runoff. New irrigation technologies (e.g., drip systems, smart sensors) improve efficiency. Farmers are switching to less water-intensive crops like grapes and pomegranates during droughts. Water Recycling Water recycling treats residential wastewater for agricultural, industrial, or landscape use. Southern California’s Groundwater Replenishment System treats and injects water into local aquifers. This reduces reliance on over-pumping and combats seawater intrusion. Water Scarcity Water scarcity is a major issue in many regions, with distant water sources requiring long daily treks. Dams and reservoirs have traditionally addressed water supply but can harm the environment. Droughts deplete reservoirs and increase evaporation, limiting their effectiveness. 25% of the global population faces reduced water access due to dam-related diversions. Privatization of Water Privatized water management often leads to higher prices than municipal systems. Atlanta reclaimed control of its water supply after privatization led to high costs and poor quality. Nestlé's purchase of Sacramento’s water rights caused controversy during California’s water shortages. Water Harvesting Water harvesting captures and stores rainwater for future use. Ancient techniques still work today, such as in India’s Marwar region where it now serves 200,000 people. Harvesting reduces the need for expensive, distant water transport during shortages. Desalination Desalination removes salt from seawater to provide fresh water, especially in the Middle East and parts of the U.S. Desalination plants are costly, energy-intensive, and pose environmental risks from salt disposal. New solar-powered desalination technologies may lower costs and environmental impact. Take-Home Message Water security requires access to safe, affordable water. Solutions to water scarcity include water conservation, recycling, harvesting, and desalination. Glossary Water security: Reliable access to safe and affordable water. Drought: Extended periods of low precipitation leading to water shortages. Water recycling: Treating wastewater for reuse in agriculture or industry. Desalination: Process of removing salt from seawater to produce fresh water. Water Cleanliness Some U.S. communities, like Flint, Michigan, suffer from unsafe water. Globally, 2.5 billion people lack sanitary wastewater systems. 1.8 billion people use water contaminated with sewage. Cow Milk vs. Almond Milk Almond milk production uses less water than cow milk. California’s almond industry uses 10% of the state’s water, replacing more water- intensive crops. Cow milk production requires more water and has a 40-times larger environmental impact due to resource use and emissions. Water Quality and Environmental Impacts Pasture-Raised Dairy vs. Plant-Based Milks Environmental impacts depend on product type, production region, and what it replaces. Comparison involves energy, water use, and climate impacts. Consumers should consider these factors when choosing between products like dairy or soy milk. Improving Water Quality: Global and Local Efforts In developed countries, treated wastewater is standard. United Nations Efforts: Since 1990, over 2.5 billion people gained access to improved drinking water. Household Technologies: Local solutions like ceramic filters and solar water purifiers help in areas lacking infrastructure. Green Technologies: Green roofs and permeable pavements reduce urban runoff. Water Regulation in the United States Safe Drinking Water Act: Sets limits on contaminants in drinking water. Clean Water Act: Regulates pollution from point sources like factories. Stories of Discovery: Recycled Water for Drinking Southern California’s Groundwater Replenishment System: Recycles wastewater into drinkable water for 2.5 million people. Benefits include combating water shortages, reducing ocean pollution, and lowering reliance on imported water. Community Resistance to Water Recycling Despite technology, public opposition exists due to distrust in recycled wastewater. Outreach efforts should focus on transparency and education about the safety and benefits of water recycling. Frozen Water and Glaciers Glaciers' Role: Store freshwater for thousands of years.  Global Concern: Melting glaciers contribute to rising sea levels, potentially threatening coastal areas and disrupting ocean currents. Cryosphere: Earth’s Frozen Water The cryosphere includes all frozen water on Earth: glaciers, sea ice, seasonal snow, and permafrost. Glacial and permafrost melting contributes to sea-level rise, while sea ice melting does not. Sea ice reflects sunlight (albedo), cooling ocean water and regulating climate. Thawing permafrost releases methane, a potent greenhouse gas, accelerating global warming. Ice Ages and Glacial Impact Ice ages occur when Earth’s temperature significantly drops. Glaciers covered large areas of land, reshaping landscapes through erosion and carving out features like the Great Lakes. Glacial periods, like the most recent one, had glaciers over 1 mile thick covering parts of the continents. The Ocean’s Diverse Ecosystems 1. Intertidal Zone o Where ocean meets land, submerged at high tide and exposed at low tide. o Species like crabs, starfish, and barnacles adapt to both wet and dry conditions. 2. Neritic Zone o Shallow waters above the continental shelf with abundant sunlight. o Rich in photosynthetic organisms like phytoplankton, forming the base of the food web. o Coral reefs, diverse ecosystems, are found here. 3. Open Ocean Zones o Divided into vertical layers based on depth and sunlight. o Near-surface zones support photosynthesis and large predators like whales. o Deep zones feature bioluminescent organisms and communities near hydrothermal vents. Take-Home Message The cryosphere plays a crucial role in regulating sea levels and global climate. Ocean ecosystems vary by depth and light penetration, supporting a wide range of life forms from intertidal species to deep-sea organisms. 4o