BIOLOGY
Class Notes
10-4
Aim: Effects on Ecosystems
(A) CHEMICAL POLLUTION
o Some examples of chemical pollution are oil spills, pesticides,
herbicides
o Many chemicals involved in pollution are carcinogenic—cancer
causing
o These different types of pollutants can result in a loss of biodiversity
o Loss of biodiversity would lead to many changes within an ecosystem
o Modern agriculture uses large amounts of chemicals
o DDT breaks down slowly in the environment and accumulates in
that fat tissue of animals
o Accumulation of DDT has also decreased biodiversity
(B) LOSS OF RESOURCES
o Many resources that cannot be replaces are being completely
destroyed—nonrenewable resources
 1—loss of species
 Various species are becoming extinct because of
human actions
 Deforestation—many species are losing their habitats
 The biosphere may lose about 1 million different
species in the next 50 years

2—loss of topsoil
o Rich topsoil cannot be replaced
o Humans have not practiced proper land management
which has lead to wind and rain removing rich topsoil
o Without a rich topsoil it is more difficult to grow
many plants which are necessary for organisms

3—loss of groundwater
o Large amounts of groundwater are being used faster
than natural processes can replace them
o What are some ways we can help conserve
groundwater?
(C) HUMAN POPULATION
o The death rate of humans has decreased because of increased technology and
better sanitation
o The birth rate has increased
o This is becoming a problem because the Earth has limited resources—it will
eventually run out of resources to support all the humans