Transcript Human Impact on the Biosphere ppt

Unit 2B Human Impact on the
Biosphere
Chapter 6 in the textbook
6.1 – A Changing Landscape
Agriculture
Development
Development
• Monoculture:
• Growth of cities and
suburbs is tied to
the high standard of
living.
practice of planting
a single productive
crop, year after
year
• Most important!
Dependable food
supply
• PRODUCE A LOT
OF WASTE!!!
Industrial
Growth
• Requires a lot of
energy to produce
and power
• Burn Fossil Fuels
(coal, oil, natural
gas)
• Waste discarded
into air/water/soil
6.2 Using Resources Wisely
1. Soil Resources
• Soil is needed to grow crops
(for food!)
• Healthy soil has nutrients, few
salts, and can hold moisture
while allowing extra water to
drain
• Healthy soil is created over
long periods of time by
interactions between soil and
the plants growing in it
Soil Erosion
• The removal of soil by water and wind
• Roots of growing plants normally hold soil
in place and prevent erosion
• If plants are removed, erosion can occur
more easily
• Also, erosion carries away nutrients that
make the soil healthy
Desertification
• The process of turning farmland into
desert that occurs due to farming,
overgrazing, drought, and climate change.
Deforestation
• The loss of forests
• Forests hold soil in place
and absorb CO2
• Without forests, soil
erosion can occur and
there will be more CO2 in
the atmosphere.
• Sometimes forests can
grow back, but it can take
centuries
2. Atmospheric Resources
• We need oxygen from the air
to breathe
• Ozone (O3) in the upper
atmosphere absorbs UV rays,
protecting us from skin
damage that causes cancer.
• Greenhouse gases (carbon
dioxide, methane, and water
vapor) hold heat in the
atmosphere to regulate Earth’s
temperature
Air Pollution
• Burning fossil fuels (coal, oil, natural gas)
release pollutants (harmful materials) into
the air
• This can affect breathing, and change
climate
Forms of Air Pollution
A. Smog- Gray-brown haze formed from chemical
reactions between air pollutants
- Harmful when breathed in
Forms of Air Pollution (cont.)
B. Acid Rain- Two of the elements released into the air
by the burning of fossil fuels are nitrogen
and sulfur
- When combined with water vapor, these
become acids, and fall as acid rain (below
pH of 5.0)
- Can kill plants and change the chemistry
of the soil
Forms of Air Pollution (cont.)
C. Greenhouse gases- In addition to nitrogen and sulfur, burning
fossil fuels also releases carbon into the
air as CO2
- Burning forests also release CO2
- CO2 is a greenhouse gas
- Excess greenhouse gases cause global
warming because they trap heat in the
atmosphere
Forms of Air Pollution (cont.)
D. Particulates- Microscopic particles of ash and dust
released by industries and diesel engines
- Can be breathed into the lungs and
cause health problems
3. Freshwater Resources
• We rely on fresh water for drinking, industry,
transportation, energy, and waste disposal
• Only 3% of Earth’s water is fresh (most of that is
frozen at earth’s poles)
• Freshwater ecosystems should be protected
Water Pollution
• Water pollutants come
from factories, oil spills,
automobiles, (etc.), or
can be washed off the
ground by rain.
• Most pollutants come
from industrial and
agricultural chemicals,
and residential sewage.
Positive Synergy
• Occurs when two pollutants have little
effect on their own, but multiply each
others effect when combined
Industrial and Agricultural
Chemicals
• Rainwater washes waste chemicals, fertilizers
and pesticides into the water supply.
• Excess fertilizer in the water can lead to
eutrophication
• When organisms (like primary producers) in the
water pick up chemicals, their bodies can’t get
rid of them, so they store them in their cells.
• When the consumers eat the producers, they eat
and store the chemicals too.
Biological Magnification
• As chemicals stored in
organisms travel up the
food chain, they become
more concentrated in the
bodies of the organisms
• This process is called
biological magnification
Biological Magnification (cont.)
• The higher the trophic
level, the greater the
concentration of chemicals
• Roughly 10 times greater
at each trophic level
• This can cause serious
problems for wildlife, and
even for humans who eat
fish
6.3 Biodiversity
Biodiversity• The variety of all forms of life in the
biosphere.
• Three types: ecosystem diversity, species
diversity, and genetic diversity.
3 Types of Biodiversity
1. Ecosystem Diversity- The variety of
habitats, communities, and ecological
processes in the biosphere.
2. Species Diversity- the number of
different species in the biosphere
3. Genetic Diversity- all of the variations in
genetic information (genes) carried by
the organisms of the biosphere.
Threats to Biodiversity
•
Human activities can alter biodiversity by
causing the extinction of certain species.
1. Altered habitats: changing or removing a
habitat to farm or build on the land
- Habitat fragmentation- splitting an ecosystem
into pieces by developing an area
2. Hunting: killing animals for food, sport, or
to sell body parts (like skin, fur, tusks,
etc.)
3. Invasive species (also called “introduced”
or “exotic”): non-native organisms brought
into an ecosystem.
4. Pollution: forms of pollution can affect the
ability of new generations to survive.
- Pesticides can prevent birds from laying
eggs
- Acid rain can make water more acidic,
affecting the survival of aquatic organisms
5. Climate Change: the increase in global
temperature.
- species are adapted to survive in a
certain temperature range.
- it is uncertain how disruptive climate
change will be to the biodiversity on Earth.
Conserving Biodiversity
1. Protect Individual Species- placing
endangered species into zoos or
aquariums where they can safely
reproduce.
- The goal is to later place the organisms back
into the wild.
Conserving Biodiversity (cont.)
2. Preserving Habitats and Ecosystemsprotect the areas where organisms live.
- Ecological Hot Spots- places with large
numbers of species and habitats that are in
danger of extinction.
Conserving Biodiversity (cont.)
3. Incentives to change behavior- US government offers tax credits to
people who put up solar panels or buy
hybrid cars
- Industries are paid money when they
release less pollution
6.4 Meeting Ecological
Challenges
Renewable Resources
•
Resources that can be
produced or replaced
quickly after they have been
used.
Examples:
1. Trees- can grow back (relatively)
quickly after they have been cut
down.
2. Sun, wind, water, geothermal (all
can be used for energy)
3. Biomass- garbage, wood, waste,
plants, landfill gases (all can be
reused for energy)
Nonrenewable Resources
•
Resources that can not be
replenished within a
reasonable amount of time
after they have been used.
Examples:
1. Fossil Fuels- coal, oil, natural
gas
-
Take millions of years to form
Once they are used up, they
will be gone forever
These
resources
are “finite”!!
Ecological Footprint
• Refers to the human impact on
the environment
• Describes the total land and
water needed to provide for an
individual and make harmless its
wastes
• Takes into account what is
needed to provide energy, food,
water, and shelter, and to
absorb wastes like sewage and
greenhouse gases
Comparing Footprints
• It is hard to calculate the exact size a
footprint for a person, country, or the world
• Estimated footprint sizes show that
Americans have a footprint 4 times larger
than the global average
Comparing Footprints
Sustainability
•
The ability to use resources in a
responsible way, thinking about the
future
Examples:
1.
2.
3.
4.
5.
6.
7.
leave stems and roots from crops to prevent erosion
Replant trees
Sewage treatment to protect the water
Plants roots filter water in the ground, so maintain the
land that the water runs through
Remove cars that pollute excessively from the road
Remove excess chemicals from gasoline
Use more renewable resources than nonrenewable
A Sustainable Future•
•
Means how to face ecological challenges
so that our resources are not gone or
unhealthy in the future
How do scientists face ecological
challenges?
1. Recognize the problem
2. Determine the causes
3. Show us how to change our behavior to help
or fix the problem