Transcript What are resources?

What are resources?
Objectives
• Distinguish between renewable and nonrenewable
resources.
• Identify renewable and nonrenewable resources.
Vocabulary
– natural resource
– renewable resource
– sustainable yield
– nonrenewable resource
What are resources?
What are resources?
• You and every other living thing on Earth must
have certain resources to grow, develop,
maintain life processes, and reproduce.
• In addition to food and water, most animals also
need shelter.
What are resources?
Natural Resources
• Natural resources are the resources that Earth
provides, including air, water, and land; all living
things; and nutrients, rocks, and minerals in the
soil and deep in Earth’s crust.
• Neither matter nor energy can be created or
destroyed, but both can be changed from one
form to another.
• Natural resources are changed through cycling,
as in the carbon, nitrogen, and water cycles.
What are resources?
Renewable Resources
• Renewable resources are natural resources
that can be used indefinitely without causing a
reduction in the available supply.
• Resources that exist in an inexhaustible
supply, such as solar energy, also are
renewable resources.
• Renewable resources are replaced through
natural processes at a rate that is equal to,
or greater than, the rate at which they are
being used.
What are resources?
Renewable Resources
Living Things
– Plants and animals reproduce, and therefore, as
long as some mature individuals of a species
survive, they can be replaced.
– Humans who use natural resources responsibly
are practicing management techniques to replace
resources as they are used.
– A sustainable yield results when renewable
resources are replaced at the same rate at which
they are consumed.
What are resources?
Renewable Resources
Sunlight
– The Sun provides an inexhaustible source of
energy for all processes on Earth.
– Sunlight is considered to be a renewable resource
because it will continue to be available for at least
the next 5 billion years.
What are resources?
Nonrenewable Resources
• A nonrenewable resource is a resource that
exists in a fixed amount in various places in
Earth’s crust and can be replaced only by
geological, physical, and chemical processes
that take hundreds of millions of years.
• Nonrenewable resources
are exhaustible because
they are being extracted
and used at a much
faster rate than the
rate at which they
were formed.
What are resources?
Distribution of Resources
• Natural resources are not distributed evenly
on Earth.
• The availability of natural resources helps
determine the wealth and the power of countries
around the world.
• The United States has a high standard of living
and it consumes approximately 30 percent of
Earth’s mineral and energy resources each year,
even though it has only 6 percent of the world’s
population.
What are resources?
Distribution of Resources
This graph shows
the percentage of
crude oil that is
consumed by the
United States and
worldwide. Note
that the United
States consumes
27 percent of the
total crude oil used
each day.
Land Resources
Objectives
• Describe why land is considered to be a natural resource.
• Recognize the need to protect Earth’s land as a resource.
• Explain how humans adjust to the uneven distribution
of land resources.
Vocabulary
– desertification
– ore
– bedrock
– gangue
– aggregate
Land Resources
Land Resources
• Land is a valuable natural resource.
– Land provides places for humans and other
organisms to live and interact.
– Land also provides spaces for the growth of crops,
forests, grasslands, and for wilderness areas.
Land Resources
Protected Land
• Of all the land in the United States, 42 percent is
certified as public land, which consists of forests,
parks, and wildlife refuges.
• These land areas are federally administered to
protect timber, grazing areas, minerals, energy
resources, and recreational interests.
• National forests are managed for sustainable
yield and include multiple-use areas where
resources are used for many purposes, including
recreation.
Land Resources
Protected Land
• Wilderness areas are places that are maintained
in their natural states and protected from
development.
• The national park system preserves scenic and
unique natural landscapes, preserves and
interprets the country’s historic and cultural
heritage, and provides areas for various types
of recreation.
• National wildlife refuges provide protection of
habitats and breeding areas for wildlife, and some
provide protection for endangered species.
Land Resources
Soil
• It can take up to 1000 years to form just a few
centimeters of topsoil, yet it can be lost in a matter
of minutes as a result of erosion by wind or water.
• The loss of topsoil makes soil less fertile and less
able to hold water, which results in poorer crops.
• Topsoil is currently eroding faster than it forms on
about one-third of Earth’s croplands.
Land Resources
Soil
• Desertification, which can occur in arid and semiarid areas of the world, is the process whereby
productive land becomes desert.
• Desertification can be prevented by reducing
overgrazing and by planting trees and shrubs to
anchor soils and retain water.
Land Resources
Bedrock
• Underneath the topsoil is a layer of soil consisting
of inorganic matter, including broken-down rock,
sand, silt, clay, and gravel.
• Bedrock is a base of unweathered parent rock
underlying the soil that may consist of limestone,
granite, marble, or other rocks that can be mined
in quarries.
Land Resources
Aggregates
• An aggregate is a mixture of gravel, sand, and
crushed stone that naturally accumulates on or
close to Earth’s surface.
• Aggregates are found in river valleys, in alluvial
fans, and in glacial moraines, eskers, kames,
and outwash plains.
• Aggregates used in construction are mixed with
cement, lime, gypsum, or other materials to form
concrete or mortar.
• The most commonly used natural aggregates are
sand, crushed or broken rocks, and gravel.
Land Resources
Ores
• An ore is a useful, natural resource that can be
mined at a profit.
• Ores can be classified by the manner in which
they formed.
• Some ores are associated with igneous rocks,
whereas others are formed by processes at
Earth’s surface.
Land Resources
Ores
Settling of Crystals
– Ores associated with igneous rocks may contain iron,
chromium, and platinum.
– Chromium and platinum ores can form when minerals
crystallize and settle to the bottom of a cooling body
of magma.
Land Resources
Ores
Hydrothermal Fluids
– Hydrothermal fluids are the most important sources of
metallic ore deposits.
– Atoms of metals such as copper and gold do not fit into
the crystals that form during the cooling process and
become concentrated in the remaining magma.
– Eventually, a solution rich in metals and silica moves
into the surrounding rocks to create ore deposits,
known as hydrothermal veins, along faults and joints.
Land Resources
Ores
Chemical Precipitation
– Ores of manganese and iron most commonly originate
from chemical precipitation in layers.
– Iron ores in sedimentary rocks are often found in bands
made up of alternating layers of iron-bearing minerals
and chert called banded iron formations.
Land Resources
Ores
Placer Deposits
– Heavy sediments, such as grains of gold and silver,
may be deposited in bars of sand and gravel when
stream velocity decreases.
– Placer deposits are sand and gravel bars that contain
heavier sediments such as gold nuggets, gold dust,
diamonds, platinum, and gemstones, as well as
rounded pebbles of tin and titanium oxides.
Land Resources
Ores
Concentration by Weathering
– Some ores form when the minerals in rocks are
concentrated by weathering.
– Aluminum forms in bauxite through weathering in
tropical climates.
– Other metals that become more concentrated as rocks
weather include nickel, copper, silver, lead, tin,
mercury, uranium, and manganese.
Land Resources
Other Land Resources
• Clay is used to make bricks, china, ceramics, tiles,
and pottery.
• Salt, or sodium chloride, occurs in deposits both
on Earth’s surface and underground.
• Deposits of both salt and gypsum, which is used
to make plaster, can form when seawater
evaporates.
Land Resources
Using Land Resources
• The extraction of some resources can have
negative impacts on the surrounding environment.
– Mines can destroy the original ground contours and
leave behind waste rock that can release pollutants.
– Gangue, which is the material left after ore is extracted
through grinding the parent rock, may release harmful
chemicals into groundwater or surface water.
– Mercury is used to extract gold from alluvial deposits.
– Materials that form acids as they weather, such as
pyrite, can be exposed through mining.
– Mining has been identified as the most dangerous
occupation in the United States.
Air Resources
Objectives
• Recognize that the atmosphere is an Earth resource.
• Describe the importance of clean air.
Vocabulary
– pollutant
– air pollution
Air Resources
Air Resources
• Air contains substances that all organisms need
to survive, including nitrogen, carbon dioxide,
hydrogen, helium, methane, ozone, neon,
and argon.
• Water vapor can make up as much as five
percent of air by volume.
• For animals, the most important component of
air is oxygen.
Air Resources
Origin of Oxygen
• Most organisms on Earth require oxygen or
carbon dioxide to maintain their life processes.
– Scientists hypothesize that 4.6 to 4.5 billion years ago,
Earth’s atmosphere included primarily carbon dioxide,
nitrogen, and water vapor.
– Early life-forms in the seas used carbon dioxide during
photosynthesis and released oxygen and water vapor.
– Over time, oxygen in the atmosphere built up to levels
that allowed the evolution of organisms that required
oxygen for life processes.
Air Resources
Disrupting Earth’s Cycles
• The geochemical cycles of Earth’s atmosphere
are in a delicate balance.
– Volcanic eruptions release various gases and dust
particles into the atmosphere.
– Photosynthetic organisms in the oceans and on land
take in and use carbon dioxide and release oxygen.
– Other organisms take in this oxygen and release
carbon dioxide.
Air Resources
Disrupting Earth’s Cycles
• Human activities that release carbon dioxide into
the atmosphere, such as burning fossil fuels, can
disrupt the geochemical cycles.
• Global warming, which is the gradual rising of
Earth’s average surface temperature, may be one
result of the human alteration of the carbon cycle.
• Deforestation has changed precipitation
patterns in the tropical rain forests of the
Amazon River Basin.
Air Resources
Disrupting Earth’s Cycles
In the Amazon River
Basin, scientists estimate
that 1 hectare (ha, about
2.47 acres) of rain forest
is cut down each hour.
Nearly 20 million ha of
rain forest is destroyed
each year worldwide.
This graph indicates the
fate of the world’s
tropical rain forests if
the current rate of
deforestation continues.
Air Resources
Disrupting Earth’s Cycles
• Nitrogen oxides released by human activities are
converted to nitric acid, which returns to Earth in
acid precipitation.
• Sulfur released into the atmosphere is converted to
sulfuric acid, which also forms acid precipitation.
• Pollutants are substances that can adversely
affect the survival, health, or activities of
organisms.
• Air pollution results when pollutants in air occur
in quantities that become harmful to human health
and the health of the environment.
Air Resources
Sources of Air Pollution
• Air pollution has both natural and human origins.
– Natural sources of air pollution include volcanic
eruptions and forest fires.
– Human sources of air pollution include gases, smoke,
and dust.
– The largest human source of air pollution is the burning
of fossil fuels in power plants and motor vehicles.
– In some large cities, motor vehicles are responsible for
80 to 88 percent of the air pollution.
Air Resources
Sources of Air Pollution
• When humans inhale harmful gases, the gases
can be absorbed by the bloodstream and interfere
with various body systems.
• Pollution can also cause burning eyes, irritated
throats, and breathing difficulties.
• As clean air in the troposphere moves across
Earth’s surface, it collects both naturally occurring
and human-made pollutants.
Air Resources
Sources of Air Pollution
Transport and Dilution
– Transport of pollutants downwind from their origin
depends upon wind direction and speed, topographical
features, and the altitude of the pollutants.
– If air movement in the troposphere is turbulent, some
pollutants are diluted and spread out, which reduces
their concentration.
Air Resources
Sources of Air Pollution
Transformation and Removal
– Some pollutants undergo chemical changes, called
photochemical changes, that are triggered by reactions
with ultraviolet (UV) radiation.
– Some air pollutants can undergo physical changes and
become heavy enough to fall back to Earth’s surface.
– Air pollutants are removed from the atmosphere in
precipitation, which includes snow, mist, and fog, as
well as rain.
Air Resources
Indoor Air Pollution
• About 90 percent of the furniture sold in the
United States also contains formaldehyde,
which is just one of the many air pollutants
that occurs indoors.
Air Resources
Indoor Air Pollution
Air Resources
Indoor Air Pollution
“Sick” Buildings
– Indoor air pollutants have been linked to headaches,
coughing, sneezing, burning eyes, nausea, chronic
fatigue, and flulike symptoms.
– A building is said to be “sick” when these symptoms
are experienced by 20 percent of its occupants.
– Often, these symptoms disappear when the affected
people go outside.
– New buildings are more likely to be “sick” than
older buildings.
Air Resources
Indoor Air Pollution
Radon Gas
– Radon-222 is a colorless, odorless, and tasteless
naturally occurring gas produced by the radioactive
decay of uranium-238.
– Outdoors, radon gas seeps from the ground into the
atmosphere, where it is diluted to harmless levels.
– Radon gas can enter through cracks in a foundation
and build up to high levels indoors.
– Once indoors, radon gas decays into radioactive
elements that can be inhaled, causing an increased
risk of lung cancer.
Water Resources
Objectives
• Explain the importance of clean freshwater.
• Analyze how water is distributed and used on Earth.
• Identify ways in which humans can reduce the need for
increasing production of freshwater resources.
Vocabulary
• desalination
Water Resources
Water Resources
• The oceans contain 97 percent of the planet’s
water, which means that only 3 percent of
Earth’s water is freshwater.
• Of this freshwater, about 2.997 percent is either
locked up in ice caps and glaciers or stored as
groundwater that is too deep to extract.
• Only 0.003 percent of Earth’s total volume of
water is available to humans for domestic,
agricultural, and industrial purposes.
Water Resources
The Importance of Water
• About 71 percent of Earth’s surface is covered
by water.
• The oceans help regulate climate, provide
habitats for marine organisms, dilute and degrade
many pollutants, and help shape Earth’s surface.
• Freshwater is an important resource for
agriculture, transportation, recreation, and
numerous other human activities.
• Most animals are about 50 to 65 percent water by
weight, and even trees may be composed of up to
60 percent water.
Water Resources
The Importance of Water
Liquid Water
– Water can exist as a liquid over a wide range of
temperatures because of the hydrogen bonds between
water molecules.
– The hydrogen bonds cause water’s surface to contract
and allow water to adhere to and coat a solid.
– Water also has a high boiling point, 100°C, and a low
freezing point, 0°C.
Water Resources
The Importance of Water
Heat Storage Capacity
– Liquid water can store a large amount of heat without a
correspondingly high increase in temperature.
– This property protects organisms that live in water from
abrupt temperature changes, and it is also responsible
for water’s ability to regulate Earth’s climate.
– Water absorbs large quantities of heat as it changes
into water vapor.
Water Resources
The Importance of Water
Water as a Solvent
– Liquid water can dissolve a wide variety of compounds.
– This ability enables water to carry nutrients into, and
waste products out of, the tissues of living things.
– Water also dilutes water-soluble waste products of
humans and thus serves as an all-purpose cleanser.
Water Resources
The Importance of Water
Solid Water Expands
– Water expands when it freezes.
– Because ice has a lower density than liquid water, it
floats on top of water causing bodies of water to freeze
from the top down.
– Ice forming in existing cracks can fracture rocks, thus
becoming part of the weathering process.
Water Resources
Location of Freshwater Resources
• Freshwater resources are not distributed evenly
across Earth’s landmasses.
– Although the United States has plenty of freshwater,
much of it is concentrated in the eastern states or
has been contaminated by agricultural or industrial
processes.
– Worldwide, water distribution is a continuing problem,
even though most continents have plenty of water.
– About 25 countries, primarily in Africa, experience
chronic water shortages.
Water Resources
Location of Freshwater Resources
Countries experience
severe water stress
when there is less
than 1000 m3 of
freshwater per
person. Extreme
water stress occurs
when there is less
than 500 m3 of
freshwater per
person.
Water Resources
Use of Freshwater Resources
• The current rate of withdrawal of freshwater from
both surface and groundwater sources worldwide
is five times greater than it was just 50 years ago.
– About 70 percent of the water withdrawn each year is
used to irrigate 18 percent of the world’s croplands.
– About 23 percent of freshwater is used for cooling
purposes in power plants, for oil and gas production,
and in industrial processing.
– About 7 percent goes to domestic and municipal uses.
Water Resources
Use of Freshwater Resources
Water Resources
Managing Freshwater Resources
• Most countries manage their supplies of
freshwater by building dams, transporting surface
water, or tapping groundwater.
• Some countries also have had success removing
the salts from seawater to provide needed
freshwater supplies.
Water Resources
Managing Freshwater Resources
Dams and Reservoirs
– Building dams is one of the primary ways that countries
try to manage their freshwater resources.
• Large dams are built across river valleys, usually to
control flooding downstream.
• Reservoirs behind dams capture the rivers’ flow, as
well as rain and melting snow.
• Dams and reservoirs currently control between 25
and 50 percent of the total runoff on every continent.
Water Resources
Managing Freshwater Resources
Transporting Surface Water
– Many countries use aqueducts, tunnels, and
underground pipes to bring water from areas where it
is plentiful to areas in need of freshwater supplies.
• The California Water Project transports water from
northern California to southern California.
• There is a demand for even more water to be
diverted to the south to which the residents of
northern California object.
• Conflicts over the transport of surface water will
probably increase as human populations create
higher demands for water.
Water Resources
Managing Freshwater Resources
Tapping Groundwater
– In the United States, about 23 percent of all consumer
freshwater consists of groundwater pumped from
aquifers.
– Groundwater normally moves from points of high
elevation and pressure to points of lower elevation and
pressure at a rate of only about 1 m/year.
– Drawdown occurs when the withdrawal rate of an
aquifer exceeds its natural recharge rate, and the water
table is lowered.
– Groundwater depletion can affect stream flow and can
result in the intrusion of salt water into shallow aquifers
in coastal areas.
Water Resources
Managing Freshwater Resources
Desalination
– Desalination is the process of removing salt from
ocean water to provide freshwater.
– Desalination occurs when salt water is distilled.
• The water is first heated until it evaporates, then it
is condensed and collected.
• The evaporation process leaves the salts behind.
• Most countries that use desalination to produce
freshwater use solar energy to evaporate sea water.
Water Resources
Managing Freshwater Resources
Reducing Freshwater Use
– The best way to meet the need for freshwater is to use
available supplies more efficiently.
• Farmers can prevent evaporation of irrigation
water by using irrigation methods such as
trickle irrigation.
• Industries can use recycled water instead of clean
freshwater for manufacturing processes.
• Many domestic uses can be reduced by installing
low-flow toilets, using plants that are droughtresistant for landscaping, and fixing leaky pipes
and faucets.