Transcript G The clean-up teams - Papanui High School

G
The clean-up teams
The clean-up teams
Decomposers
Compost
Sewage treatment
Nutrient cycles
The clean-up teams
As living things, all microbes need a source of energy
(food). However, this ‘food’ need not be compounds we
consider edible. There are microbes that break down
oil spills, remove excess nitrogen from polluted water,
turn smelly H2S gas into sulfates and make fossil fuels
from buried swamps.
An oil-contaminated
beach can clean itself
within a few months
through the action of
naturally-occurring
bacteria which digest
hydrocarbons.
Decomposers
A decomposer is an organism
that breaks down materials,
changing them into smaller
particles. While earthworms,
maggots and slaters are
classified as decomposers,
most decomposition is done by
a wide variety of bacteria and
fungi.
These microbes make nutrients
such as nitrogen, sulfur,
phosphorus and carbon
available to other living things.
Saprophytic mushrooms are
beginning to break down
this tree stump.
Trees use nutrients from the
soil to make wood and leaves.
Dead leaves are broken
down by microbes to
make nutrient-rich soil.
The dead wood is broken
down by invertebrate and
microbial decomposers.
Compost
When we compost kitchen and
garden waste, we speed up the
natural process of
decomposition. The centre of a
compost heap gets hot, and this
allows thermophilic (heat loving)
microbes to thrive. These
microbes are able to break down
more complex molecules (such as
fat), and the heat they generate
kills weed seeds and pathogenic
microbes. The finished compost
becomes a valuable nutrient
source for a new crop of plants.
Sewage treatment
Sewage contains human waste and often contains
human pathogens. Sewage treatment plants are needed
to prevent these human pathogens from spreading.
A variety of aerobic and anaerobic microbes are used
in sewage treatment which digest the compounds
contained in the sewage. Human pathogens die because
the conditions at the sewage plant are not suitable for
their survival.
Nutrient cycles
Ecosystems are very
complicated. You may
have drawn food
chains or food webs to
show how energy
moves through an
ecosystem. Scientists
draw nutrient cycles,
such as the nitrogen
cycle or the carbon
cycle, to show how
specific elements are
recycled within an
ecosystem.
The nitrogen cycle shows how
nitrogen is recycled in nature.
The clean-up teams
Microbes live in many different conditions and can obtain
energy from many different types of compounds.
Most decomposition of dead plant and animal material is
done by microbes. This decomposition recycles nutrients
such as nitrogen, carbon, sulfur and phosphorus, making
these elements available for other living things.
Composting recycles kitchen and garden waste in a heap
with a hot centre that kills weed seeds and pathogens.
Sewage treatment uses microbes to break down human
waste products.
6G 1 A heap of rot 6G 2 Sewage treatment
6G 3 The nitrogen cycle
6G 4 Quiet! Microbes at work
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