Transcript Ch 6 Humans in the Biosphere

1 Review What causes soul erosion? Why is soil erosion
a problem
Apply Concepts What are 3 ways in which the
agricultural and forestry industries can improve the
sustainability of soil
2 Review How is fresh water both a renewable and a
limited resource
Explain why are some pollutants more harmful to
organisms at higher trophic levels
Propose a Solution Pick one source of water pollution
and describe a way in which we can reduce its effect.
CH 6 HUMANS IN THE BIOSPHERE
6.2 Using Resources Wisely
Soil Resources

Topsoil
 Mineral
and nutrient-rich portion of soil
 Absorbs and retains moisture
 Rich in organic matter and nutrients
 Allows water to drain
 Low in salts.
Soil Resources


Can be a renewable resource if it is managed
properly
Can be damaged or lost if it is mismanaged
 1930’s
“Dust bowl.”
Soil Erosion




Removal of soil by water or wind
Occurs fasters without plants
Also removes organic materials
Humans cause by over use of land and logging.
Desertification
Process of farmland
or other productive
biome into desert
 Change due to
overgrazing, over
farming, or drought
 40 percent of Earth’s
land is at risk.

Deforestation



Loss of forests
Hold soil in place, protect the quality of fresh
water supplies, absorb carbon dioxide, and help
moderate local climate
Forests can regrow after cutting, but it takes
centuries for succession to produce mature, oldgrowth forests
 Old
growth considered non renewable.
Soil Use and Sustainability



Leaving stems and roots of the previous year’s crop
in the soil
Crop rotation
Contour plowing
 Plant

crops across and not down slopes
Terracing
 Shaping

the land to create level “steps”
Selective harvest of trees.
Freshwater Resources


Can be either renewable or non renewable
Only 3 percent of Earth’s water is fresh water and
most of that is locked in ice at the poles.
Water Pollution

Pollutant
 Harmful

material that can enter the biosphere
Point source pollution
 Enter
water supplies from a single source
 Think an actual pipe

Non point source pollution
 Enter
water supplies from many smaller sources.
Water Pollution


May enter both surface water and underground
water
Primary sources are industrial and agricultural
chemicals, residential sewage, and nonpoint
sources.
Biological Magnification

When a pollutant, such
as DDT, mercury, or a
PCB, is picked up by an
organism and is not
broken down or
eliminated from its
body.
Biological Magnification




Primary producers pick up a pollutant from the
environment
Herbivores eat those producers and concentrate
and store the compound
Carnivores eat the herbivores and concentrate and
store the compound
Concentrations may reach 10 million times their
original concentration.
Residential Sewage




Contains lots of nitrogen and phosphorus
Can stimulate blooms of bacteria and algae that
rob water of oxygen
Oxygen-poor areas called “dead zones” can appear
Also contains microorganisms.
Water Quality and Sustainability





Protect wetlands
Sewage treatment
Pollution control
Careful agricultural practices
Water conservation.
Atmospheric Resources



Oxygen
Ozone
Greenhouse gases.
Air Pollution

Smog
 Chemical
reactions in industrial processes and
automobile exhaust

Acid rain
 Nitrogen
and sulfur compounds combine with water
to form nitric and sulfuric acid
 From burning fossil fuels.
Air Pollution

Greenhouse gases
 Burning
fossil fuels and forests releases stored carbon
 Agriculture releases methane

Particulates
 Microscopic
particles of ash and dust released by
certain industrial processes and certain kinds of diesel
engines.
Air Quality and Sustainability

Emission standards and clean-air regulations.
1.
2.
3.
Each year, the U.S. EPA estimates emissions from a
variety of sources. Look at the graph on pg 137.
Interpret Data Describe the overall trend in
emissions since 1980. Is this what you would
expect given the trends in energy consumption
and automobile travel- Explain?
Interpret Data How does the graph differ from
one that shows absolute values for emissions?
Describe that graph/
Infer What do you think has contributed to the
trends you see in this graph? Why would the EPA
be particularly interested in this data?