How long can humans typically live without food? 3 Weeks
How long can humans typically live without water? 3 days
What two kinds of water are found on Earth? Fresh water and salt water.
Which type of water do most human uses require? Fresh water
Is water a renewable or non-renewable resource? Why? Renewable resource; it is circulated in the water cycle.
Why are oceans important? Almost all of Earth’s water is in the oceans.
What percent of Earth’s surface is covered in water? 71%
What percent of Earth’s water is salt water in oceans and seas? Nearly 97%
About what percent of Earth’s fresh water is frozen in glaciers and polar icecaps? Approximately 77%
The freshwater that humans use mainly comes from where? Lakes and rivers and from a relatively narrow zone beneath Earth’s surface.
What is surface water? All the bodies of fresh water, salt water, ice, and snow that are found above ground.
How do streams form? As water from falling rain and melting snow drains mountains, hills, plateaus, and plains.
What is a river system? A flowing network of rivers and streams draining a river basin.
What is the largest river system in the world? Amazon River system.
What is a watershed? The area of land that is drained by a water system.
Why does the amount of water in a watershed vary throughout the year? Rapidly melting snow as well as spring and summer rains can dramatically increase the amount of water in a watershed. At other times of the year, the river system that drains a watershed may be reduced to a trickle.
Where does most of the freshwater that is available for human use exist? Underground
What is groundwater? The water that is beneath the Earth’s surface.
What is an aquifer? Body of rock or sediment that stores groundwater.
What is porosity? The percentage of the total volume of a rock or sediment that consists of open spaces.
What is permeability? The ability of a rock or sediment to let fluids pass through its open spaces or pores.
What is an example of a permeable material? Gravel, sandstone, limestone, sand, etc.
What is an example of an impermeable material? Clay, granite, etc.
What is a recharge zone? An area in which water travels downward to become part of an aquifer.
Why are recharge zones environmentally sensitive? Because any pollution in the recharge zone can also enter the aquifer.
What is a well? A hole that is dug or drilled to reach groundwater.
According to the World Health Organization, how many people lack access to a clean, reliable source of fresh water? 1 billion people.
What are the three major uses for water? Residential use, agricultural use, and industrial use.
Most of the freshwater used worldwide is used for what purpose? To irrigate crops
What percent of water used in the world is used for industrial purposes? 19%
What percent of water used worldwide is for household purposes? 10%
How many gallons of water does the average person in the United States use per day? 79 gallons
How many gallons of water does the average person in India used per day? 11 gallons
What is a pathogen? A virus, microorganism, or other substance that causes disease.
What purposes does industry around the world use water to meet? Manufacture goods, dispose of wastes, and to generate power.
How much water used in the world is used for agricultural purposes? 67%
As much as what percentage of the water used in agriculture evaporates? 80%
What is irrigation? A method of providing plants with water from sources other than direct precipitation.
What are the various goals that water management projects can meet? Bringing water to make a dry area habitable, creating a reservoir for drinking water, or generating electric power.
What is a dam? A structure that is built across a river to control a river’s flow.
What is a reservoir? An artificial body of water that usually forms behind a dam.
What is a hydroelectric dam? Use the power of flowing water to turn a turbine that generates electrical energy.
What is percent of the world’s electrical energy is generated using hydroelectric dams? 20%
Interrupting a river’s flow can have consequences, what are these consequences? Land behind a dam is flooded – people are displaced and entire ecosystems can be destroyed. Fertile sediment builds up behind a dam instead of enriching the land farther down the river and farmland below may be less productive. Dam failure can be another problem – if a dam bursts the people living along the river below may be killed.
What is one method to help prevent so much water loss due to evaporation in agricultural uses of water? Drip irrigation systems.
What is the most widely used water conservation practice in industry? The recycling of cooling water and wastewater.
What are some household technologies that have been developed to save water? Low-flow toilets, watering at night, xeriscaping.
What are two possible solutions to water shortage problems? Desalination and transporting fresh water.
What is desalination? The process of removing salt from ocean water.
Why is it not possible for some countries to use desalination practices? It consumes a lot of energy and is too expensive.
What is water pollution? The introduction into water of waste matter or chemicals that are harmful to organisms living in the water or to those that drink or are exposed to the water.
What are the two underlying causes of water pollution? Industrialization and rapid human population growth.
What pollution comes from two types of sources, what are these sources? Point and nonpoint sources
What is point-source pollution? Discharged from a single source
What is an example of point-source pollution? Factory, wastewater treatment plant, leaking oil tanker, etc.
What is non-point source pollution? Pollution that comes from many sources rather than from a single specific site.
What is an example of non-point source pollution? Pollution in a body of water from streets and storm sewers.
What is wastewater? Water that contains wastes from homes or industry.
What is one way communities have used wastewater sludge? Toxicity can be reduced to safe levels and used as fertilizer; combined with clay to make bricks.
What is artificial eutrophication? A process that increases the amount of nutrients in a body of water through human activities, such as waste disposal and land drainage.
What are the major causes of eutrophication? Fertilizer and phosphates
Why is eutrophication not a positive occurrence in an ecosystem? Eutrophication can lead to excessive algae growth. Algal blooms can form. Also, as algae die and decompose, most dissolved oxygen is used and fish and other organisms suffocate in the oxygen-depleted water.
What is thermal pollution? A temperature increase in a body of water that is caused by human activity and that has harmful effect on water quality and on the ability of that body of water to support life.
What detrimental effects can thermal pollution have on an ecosystem? It can cause large fish kills if the discharged water is too warm for the fish to survive. If the temperature of a body of water rises even a few degrees, the amount of oxygen the water can hold decreases significantly.
How do pollutants usually enter groundwater? When polluted surface water percolates down from the Earth’s surface.
Why is groundwater pollution one of the most challenging environmental problems in the world? It recharges very slowly, so the process for some aquifers to recycle water and purge contaminants can take hundreds of years. Pollution can cling to the rock and soil that make up an aquifer, so even if all of the water in an aquifer were pumped out and replaced with clean water, the groundwater could still become depleted.
What percent of ocean pollution is from activities on land, near the coasts? At least 85%
Approximately how many gallons of oil from tanker accidents is spilled into the ocean each year? About 37 million gallons
What is biomagnification? The accumulation of pollutants at successive levels of the food chain.
What was the Clean Water Act of 1972 designed to accomplish? Restore and maintain the chemical, physical, and biological integrity of the nation’s waters.
As a result of the Clean Water Act of 1972, lakes that are fit for swimming has increased by what percent? 30%
What resulted from the Oceans Act of 2000? Created the U.S. Commission on Ocean Policy to develop recommendations for a new coordinated and comprehensive national ocean policy.