Humans and the Environment
While, all living things have impacts on the
environment, humans have a larger impact than
other organisms. Some reasons for the greater
• Pursuit of resources – food, coal, wood
•Generation of wastes and pollution –
radioactivity, garbage etc
• These activities can upset ecosystem
• Prevent soil production
• Interrupt natural food pyramids and energy
Changes brought about by humans can cause
harm to populations of other organisms.
Use of resources creates wastes, changing
composition of air, soil and water.
Significant problems from pollution of the air
Ozone in the stratosphere keeps 95-99% of
the sun’s ultraviolet radiation from striking
In 1974, it was reported that ozone in the
stratosphere was declining because of man-
made compound known as
Used in styrofoam and refrigerants.
The Ozone Hole over the Antarctic
allows through UV radiation that
•Decrease in marine and amphibian
Carbon Dioxide is a product of burning fossil
fuels made up of carbon.
Carbon Dioxide is a greenhouse gas. CO2
traps heat near the Earth’s surface.
The Greenhouse effect will lead to global
warming which could cause
How Will Climate Change Influence
• Creates barriers to migration from
one climate to the other
• Environment could change faster than
pace of evolutionary change in
• Could lead to massive extinction of
Burning of coal produces sulfur dioxide
and nitrous dioxide which react with
water in the atmosphere to create
H2SO4 and HNO3
These acids combine with rain to
increase acidity (lower pH)
• Impacts of Acid Rain on the
- Acidification of Lakes
Kills aquatic insects
- Wash nutrients from soils
Impacts the food chain
• Lakes, rivers and groundwater can be
polluted from activities within a
watershed. (The land over which rain
water drains to fill bodies of water)
– Examples: Runoff from farms, inappropriate
disposal of household chemicals, discharge
from manufacturing, spills etc.
PCB’s in the Hudson River
• PCB’s are an oily liquid that were used in
electrical equipment to prevent
overheating and fires.
• PCB’s build up in the tissues of animals
because they do not like to be in water,
rather they like to be in fatty substances.
• PCB’s built up in bodies of fish and then in
the bodies of animals that eat fish
The storing of a chemical in living things is
Other Examples of Bioaccumulation
• DDT – Build up of insecticides in birds
which prevented reproduction.
• Mercury – Build of toxic metal which
causes neurological problems in animals.
Bioaccumulation influences the entire food
chain. The top predator usually has the
highest quantity of chemical.
All of these pollution related
problems influence the ecosystem
and can result in habitat loss for
Habitat is the place where a species can meet all of
its life function needs:
Where it can get the food that matches its designs,
water, appropriate shelter from cold and predation
and reproduce to continue its species.
Any impact that influences an animals ability
to meet habitat needs could cause a
decline in population of a species
In addition to air and water pollution, what
human activities can lead to habitat
– Cutting down of forests
– Building Cities that prevent movement of
– Diversion of water ways