Transcript Earth’s Nonliving Resources

Earth’s Nonliving Resources
P.Lobosco
Land and Soil Resources

More than 6 billion people now inhabit the
Earth. Materials removed from the Earth and
used by people are called natural resources.
Scientists divide the Earth’s natural resources
into two groups, nonrenewable and renewable.
Nonrenewable Resources

Nonrenewable Resources cannot be replaced
by nature. Fossil fuels are nonrenewable
resources. Minerals, such as copper and iron,
are also nonrenewable resources.
Renewable Resources

Renewable resources S can be replaced by
nature. Wood is a renewable resource. Water
is a renewable resource. Soil is also a
renewable resource, but soil formation is an
extremely slow process. Nature can take
anywhere from 500 years to 1000 years to
replace every 2.5 centimeters of topsoil that
have been lost.
Land Use

One-third of the Earth’s surface is covered by
land. Only a small amount of this land can be
used for farming or for living space. All land is
not suitable for all uses. Land is used for
cities, highways, forests, farms and pastures.
Even though the population continues to grow,
land is a limited resource.
Land Use

Land is needed for building cities to house the
increasing human population. Land is also
needed for farming and industry. These needs
have to be carefully weighed and balanced. If
too much is used for cites, then not enough will
be left for farms. Both uses are important.
Food Production

An increasing population requires an increase
in food production. New and improved crop
varieties must be developed. Farms must be
made more productive wit made fertile.h better
growing methods. Land that is unusable for
farming must be made fertile. Irrigation is one
way to do this. Land is also needed for raising
animals and to produce food for the animals.
Land Management

If limited land resources are to be preserved,
land use must be carefully planned and
managed. Different land areas are best suited
for different purposes .
Farm Management
. Crops use up nutrients in the soil. When one
type of crop is grown on the same land for too
long, depletion may result. Farmers need to
alternate crops that extract different nutrients.
This is known as crop rotation. Contour
plowing involves planting crops across the face
of a slope of land. In strip cropping, farmers
plant strips of low cover crops between strips
of other crops. This holds down the soil.
Erosion
Crops are grown in topsoil. In many areas,
topsoil is lost because of erosion. Erosion is
the carrying off of soil by water or wind. Poor
land management speeds up its process.
Worldwide topsoil is being lost 10 times faster
than new soil is being formed. Contour
plowing, strip cropping and terracing can
prevent erosion. Terracing is plowing the slope
into a series of level steps to slow down water
runoff. Windbreaks prevent wind erosion.
Desertification

Regions too dry to support crop growth ca
support grasslands. These grasslands have
traditionally been used for grazing. Too many
animals on the land results in overgrazing.
Overgrazing leaves the topsoil exposed to wind
erosion. Dry grasslands then become deserts.
Desertification is taking place all over the
world.
Land and Soil Reclamation

Sometimes land is disturbed to reach valuable
minerals. It may be possible for the land to be
reclaimed, or restored to its original condition. Land
reclamation involves several steps. First, the valuable
topsoil is carefully removed and stored. Then the less
valuable layers below are stripped away. The needed
minerals are removed and shipped. The disturbed soil
must be protected from erosion and pollution. Then
the layers are put back. The final step is seeding and
planting the land.
Water Resources

Even though water is a renewable resource,
there is a limited supply of fresh water. Most of
the Earth’s water, 97%, is in the oceans.
Uses of Water

In the United States, billions of liters of water
are used every day. Each person in the United
States uses more than 260 liters of water daily.
Water is also needed for irrigation. Industry
uses more than 60 billion liters of water every
day.
Water Supply

The Earth’ supply of fresh water is constantly
renewed by the water cycle. A cycle is a
continuous, repeating chain of events. The
water cycle is the movement of water from the
Earth’s surface to the atmosphere and back to
the surface.
The Water Cycle

In the first step of the water cycle, water on the Earth’s
surface is heated by the sun and evaporates. This gas
or water vapor rises into the atmosphere. As water
vapor rises into the upper atmosphere, it cools,
condenses and forms clouds. This is the second step.
During the third step of the water cycle, the water falls
back to the surface of the Earth as precipitation. Most
precipitation falls directly into oceans,lakes, rivers and
streams. Some falls to the land and runs off.
Eventually it returns to the atmosphere and the cycle
continues.
Sources of Fresh Water

Most of the Earth’s water resources are in
oceans, lakes, rivers and streams. Water is
also found in the soil as groundwater and
frozen as ice in glaciers and polar icecaps.
Water in the ocean is too salty to be used. Ice
in glaciers is not directly available. So the main
sources for fresh water for human use are
groundwater, fresh water lakes and rivers.
Groundwater

More than 300 billion liters of groundwater are
taken out of the ground daily in this country for
use on farms and in factories. Half the drinking
water in the United States comes form
groundwater. It takes hundreds of years for
groundwater to accumulate. In many areas of
the country it is being used faster than it is
being replaced. The levels of groundwater are
dropping and lakes and rivers may dry up.
New Sources of Fresh Water


Desalination is the process by which salt is
removed from ocean water. Some cities in the
United States such as Key West, Florida have
built desalination plants.These plants supply 20
million liters of fresh water daily.
Icebergs could possible be moved to large
coastal cities and mined for fresh water.
Scientists are not sure of the environmental
effects the movement of glaciers might have.
Mineral Resources

A mineral is defined as a naturally occurring
chemical substance found in soil. Minerals are
used to make a variety of products, from silver
jewelry to aluminum cans. Minerals are
nonrenewable resources. Minerals are either
metallic or non metallic.metallic minerals
include copper, iron and aluminum.
Nonmetallic minerals include quartz, limestone
and sulfur.
Ores

To obtain a useful mineral, the minerals must
be mined or removed from the Earth. Deposits
of minerals that can be mined at a profit are
called ores. If the percentage of a mineral in
an ore is high, the ore is called a high-grade
ore. Ore are found all over the Earth. The
Earth’s crust is a storehouse of minerals.
Iron

Iron is the most widely used metal extracted
from metallic ores. Other substances can be
added to iron to make steel. Steel is an alloy,
or a substance made of two or more metals.
Chromium is added in the steel making
process to provide resistance to rusting.
Other Minerals

Other metals removed from metallic ores
include copper, which is used in electric wires
and aluminum which is used in cans. Gold and
silver, used in jewelry, are also found in
metallic ores.
Mining and Processing Ores

Once mineral deposits have been located, they
must be mined. Open-pit mining can have
disastrous effect on land and groundwater
resources. Mining the ore is the first step. To
extract the mineral from the ore, impurities in
the ore are removed. A purified mineral
remains. The mineral is then processed and
sent to the plant to make the final product.
Mining the Oceans

The minerals in the Earth’s crust have been formed
over millions or billions of years. The Earth contains a
limited amount of mineral. The present rate of mining
cannot continue or the supply will be exhausted. One
answer is to reuse or recycle minerals. Another is to
find new materials to take their place. Another
possibility is the ocean floor. Many minerals such as
manganese, nickel, cobalt, and copper have been
found on the ocean floor. If these deposits can be
mined economically, they may provide a valuable new
source of mineral.