Transcript Humans in the Biosphere

Humans in the Biosphere
How have human activities shaped
local and global ecology?
The Effect of Human Activity
1. Agriculture
– Benefit: food production
– Environmental cost: impact on fresh water and
fertile soil
The Effect of Human Activity
2. Development
– Benefit: higher standard of living
– Environmental cost: production of lots of wastes
The Effect of Human Activity
3. Industrial growth
- Benefit: conveniences of modern life
- Environmental cost: requires lots of energy
to produce and power products.
Question:
• How might more productive agricultural
practices affect a developing nation’s
population?
• Its environmental health?
Sustainable Development
• Renewable resources: resources that can be
produced or replaced by a healthy ecosystem
– Ex. Plants, trees, sun…
• Nonrenewable resources: resources that can
not be replaced within a reasonable amount
of time.
– Ex: fossil fuels( coal, oil, natural gas), water
Sustainable development
• Providing for human needs while preserving
the ecosystem that produce natural resources.
– Causes no long-term harm to the soil, water and
climate
– Consume little energy and material as possible
– Flexible to survive environmental stresses
Using Resources Wisely
• 3 major environmental concerns:
– Soil erosion
– Water pollution
– Air pollution
Soil
• Healthy soil supports both agriculture and
forestry
• Topsoil – contains nutrients and minerals
essential to growth
• Can be a renewable resource if managed
properly
• Soil erosion – removal of soil by water and
wind (over farming, over grazing…)
Soil erosion
• Desertification – turning farmland into
dessert by over farming, over grazing,
seasonal drought and climate change
• Deforestation – loss of forests, trees hold soil
in place
Soil Use and Sustainability
• Leave stems and roots in ground
• Crop rotation
• Altering the shape of the land- contour
farming
Freshwater Resources
• Freshwater is usually a renewable resource
but if not removed faster than can be
replaced: nonrenewable
• Aquifer: underground water reserve
–
Water pollution
• Harmful materials that enter the biosphere
and water source
– Point source pollution: from single source like an
oil spill
– Nonpoint sources – pollution from smaller
sources, such as oil and grease off streets
• Primary pollution sources
– Agricultural chemicals, residential sewage and
nonpoint sources
Water quality and sustainability
• Watershed conservation – clean up pollution
• Sewage treatment
• IPM – integrated pest management, instead of
pesticides (ladybugs)
• Conserving water – drip irrigation
Biological Magnification
• Pollutant is picked up by an organism and not
broken down but collects in body tissues.
• As food eats food, the pollutant concentration
increases ten fold.
• At highest trophic levels, concentrations may
reach 10 million times their concentration.
– Ex. DDT, bold eagles, mercury, pregnant women
Acid Rain
• Steps:
– Coal –burning power plants put smoke high into
the atmosphere
• The smoke contains high levels of sulfur
• The smokestacks were to dissipate the smoke,
backfired
• Smoke combines with water vapor =sulfuric acid
• Acidified precipitation = ACID RAIN
Acid Rain
Effects of Acid Rain
• Most prominent in the Northeastern United
States and Southeastern Canada
– Why…
• pH scale, below 7 = Acid
– Under 5, results in damage to organisms, statues…
Effects of Acid Rain
Ozone Layer
• O3, protective shield in upper atmosphere
• Layer is thinning and disappearing
• Allows more UV rays into environment
– Why is this an issue?
Destruction of Ozone
• CFC’s – Chlorofluorocarbons
– Heat exchanger, refrigerator coolant, aerosol propellant,
foaming agents
• UV rays are strong enough to break the bonds in
CFC’s, releasing chlorine atoms, which in turn react
with ozone, destroying it
• Limit or ban use of CFC’s
– US – limit CFC’s in aerosol’s
Ozone Depletion
• CFCs escape into
amosphere
• CFCs destroy ozone
• More UV radiation
reaches Earth’s surface
• Skin cancer cases
increase
Good and Bad Ozone
• Good
– Protective layer, absorbs UV rays
– Between 11 – 16 miles above sea level
• Bad (forms when sun and emissions react)
– Corrosive, reactive gas
– Pollutant at surface levels
– Irritates and damages lungs and eyes, suppresses immune
system