Classifying Resources
¨ Environmental goods and services may be classified as either renewable or nonrenewable.
¨ A renewable
resource can regenerate if it is alive, or can be replenished by biochemical cycles
if they are nonliving.
Ø
A tree is an example of a renewable resource,
because a new tree can grow in place of an old tree that dies or is cut down.
¨ A renewable resource is not necessarily unlimited.
¨ Fresh water can easily become limited by drought or overuse.
Ø
A nonrenewable resource is one that cannot be replenished by
natural processes.
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Fossil fuels-coal, oil, and natural
gas are nonrenewable resources. When they are depleted, they are gone forever.
Sustainable Development
¨ Sustainable development is a way of using natural resources without depleting them, and
providing for human needs without causing long-term environmental harm.
¨ Human activities can affect the quality and supply of renewable
resources such as land, forests, fisheries, air, and fresh water.
¨ Sustainable strategies must enable people to live comfortably and
improve their situation.
¨ The use of insects to control insect pests is one such strategy. This may help farmers reduce the use of pesticides.
Land Resources
¨ Land is a resource that provides space for human communities and
raw materials for industry.
¨ Land also includes the soils in which crops are grown.
¨ The most fertile soil is in the uppermost layer called topsoil.
¨ Such soil is produced by long-term interactions between the soil
and plants growing in it.
¨ Plowing the land removes the roots that hold the soil in place.
¨ Soil erosion is the wearing away of surface soil by water and wind.
Ø The Midwest loses roughly 47 metric tons of topsoil per hectare every year!
¨ In dry climates, a combination of farming, overgrazing, and drought
has turned once productive areas into deserts a process called desertification.
¨ There are a variety of sustainable-development practices that guard
against these problems.
Ø Contour plowing, in which fields are plowed across the slope of
the land to reduce erosion.
Ø Leaving the stems and roots of the previous year’s crop in
place to help hold the soil.
Ø Planting a field with rye rather than leaving it unprotected from
erosion.
Forest Resources
Ø Forests have been called the “lungs of the Earth” because
they remove carbon dioxide and produce oxygen.
Ø Forests provide:
Ø Wood for homes, paper, fuel
Ø Store nutrients
Ø Provide habitats and food for organisms
Ø Moderate climate
Ø Limit soil erosion
Ø Protect freshwater supplies
¨ Worldwide, about half of the area originally covered by forests
and woodlands has been cleared.
¨ Only about one-fifth of the world’s original old-growth forests
remain.
¨ Deforestation or the loss of forests can lead to severe erosion as soil is exposed to heavy rains.
¨ Erosion can wash away nutrients in the topsoil.
¨ Grazing or plowing after deforestation can change local soils and
microclimates that may prevent regrowth of trees.
¨ There are a variety of sustainable-development strategies for forest
management:
Ø Mature trees are harvested selectively to promote growth of younger
trees and promote the forest ecosystem.
Ø Foresters plant, manage, harvest, and replant tree farms.
Ø Tree geneticists are also breeding new, faster-growing tree varieties
that produce high quality wood.
Fishery Resources
Ø Fishes and other animals that live in water are a valuable source
of food for humanity.
Overfishing
¨ Overfishing, or harvesting fish faster than they can be replaced
by reproduction, greatly reduced the amount of fish in parts of the world’s ocean.
¨ From 1950-1990, the world fish catch grew from 19 million tons to
more than 90 million tons.
¨ By the early 1990’s, populations of cod and haddock had dropped
so low that researchers thought these fish might disappear.
¨ The declining fish populations are an example of the “tragedy
of commons”.
¨ “Tragedy of commons” is when people from several countries
take advantage of a resource but no one takes responsibility for maintaining it.
Sustainable Development
Ø
Because of the declining fisheries, the U.S. National
Marine Fisheries Service created guidelines for United States
commercial fishing.
Ø
The guideline specified how many fish, and of what
size, could be caught in various parts of the oceans.
¨ The regulations are helping fish populations to recover.
¨ Unfortunately, it caused loss of jobs in the short term, but will protect the
fishing industry for the future.
Aquaculture
Ø Aquaculture is the raising of aquatic animals for human consumption.
Ø It also helps to sustain fish resources.
Ø If it is not managed properly, aquaculture can pollute water and
damage aquatic ecosystems.
Air Resources
¨ Air is a resource that affects people’s health and it’s
quality remains a challenge for modern society.
¨ Smog is a mixture of chemicals that occurs as a gray-brown haze in the atmosphere.
¨ Smog is due to automobile exhaust and industrial emissions.
¨ Smog is considered a pollutant.
¨ A pollutant is
a harmful material that can enter the biosphere through land, air, or water.
¨ The burning of fossil fuels can release pollutants into the atmosphere.
¨ Toxic chemicals are nitrates, sulfates, and particulates which are
microscopic particles of ash and dust.
¨ Most industries have to control their emissions from factory smokestacks.
¨ Strict automobile emission standards and clean-air regulations have
greatly improved air quality in U.S. cities.
¨ The release of nitrogen and sulfur compounds into the atmosphere
when combined with water vapor form strong acids.
¨ When acid rain falls, it can kill plants and change the chemistry
of soils and standing-water ecosystems.
Freshwater Resources
¨ Americans use billions of liters of freshwater daily for drinking
and washing to watering crops and making steel.
¨ Pollution threatens water supplies in several ways.
Ø Improperly discarded chemicals can enter streams and rivers.
Ø Waste discarded on land can seep through soil and enter groundwater.
Ø Domestic sewage (sinks and toilets) which contain nitrogen can encourage
growth of algae and bacteria in aquatic habitats.
Ø Sewage containing microorganisms can spread disease among humans
and animals.
¨ One way of ensuring the sustainable use of water resources is to
protect the natural systems involved in the water cycle.
Ø Wetlands help to purify the water passing through them. Densely growing plants filter certain pollutants out of the water.
Ø Forests and other vegetation help to purify the water that seeps
into the ground.
¨ Water conservation is becoming an increasingly important aspect
of sustainable development.
¨ More than three quarters of all water consumed is used in agriculture.
Ø An example of conservation would be to use drip irrigation which
delivers water directly to plant roots. This reduces the amount of water lost
through evaporation.