Transcript Pollution - Ms Curran`s Leaving Certificate Biology

1.4.9 Human Impact on an
Ecosystem 1
Pollution
Human Impact on Ecosystems
We are going to look at 3 ways that humans
affect ecosystems:
1. Pollution
2. Conservation
3. Waste Management
Note: from Syllabus Clarifications – Pollution
must be related to habitat studied.
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Pollution
What it is
Types of pollution
Pollutants
Effects of pollutants
Control of pollutants
Ecological impact of one human activity
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Pollution
Pollution is any human addition
(contamination) to a habitat or the
environment that leaves it less able to
sustain life.
It is the most harmful human impact and
affects air, fresh water, sea, soil and land.
Chemicals of human origin that harm the
environment are called pollutants.
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Industrial/Air
Pollution
Agricultural
Pollution
– slurry, if it gets
into a river/pond
Some types of Pollution
Domestic
Pollution
River/Water
Pollution
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Pollutants
are produced by human activities
• CO2 from respiration is not a pollutant –
why?
• excess CO2 from burning fossil fuels is
• SO2 from marshes & volcanoes is not –
why?
• SO2 from factory chimney is
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Pollutants
Some pollutants are normally present in an
environment, e.g. CO2, but levels are
increased by human activity.
Other pollutants never exist in an environment
e.g. oil slick, CFCs
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From the Syllabus & Guidelines
The Syllabus states: “Study the effects of
any one pollutant.”
The Guidelines for Teachers states: “Give
the effects of one pollutant from any of the
following areas: domestic, agricultural,
industrial.” and
“Give an example of one way in which
pollution may be controlled in the selected
area.”
What follows is only a sample of the
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pollutants available.
Effect of one pollutant from one area
- Agricultural, Industrial or Domestic
Area
Pollutant
Source
Effects
Washed or Formation of algal
Slurry &
Agricultural
leached
blooms and
Fertiliser
from land eutrophication
Forms ‘acid rain’
Sulphur
Burning
Industrial
dioxide
fossil fuels More detail later
Non-biodegradable
Domestic
Plastic bags Shopping Suffocate small
animals, Litter
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Eutrophication & Algal bloom
eutrophication: a condition where lakes
become over-enriched with nutrients,
resulting from excess artificial fertilisers
washed into rivers and lakes.
There is a rapid increase in the growth of alga
(algal bloom) as they use up the nutrients.
When all the nutrients are used up the algae
die and are broken down by bacteria, which
use up the oxygen in the water resulting in
the death of aquatic organisms such as fish.10
Control of Pollutants
in the selected area - Agricultural, Industrial or Domestic
Area
Pollutant
Control Measures
Agricultural
Slurry &
Fertiliser
Avoid spreading these:
• on wet, waterlogged, frozen
or steeply sloping land
• within 1.5m of any
watercourse.
Industrial
Sulphur
dioxide
Fit catalytic scrubbers in
factory chimneys
Domestic
Bag tax/levy. Reuse/Recycle
Plastic bags
bags
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Ecological impact of one
human activity
Burning Fossil Fuels
Acidic oxides and acid rain
• All rain is acidic – but not the same pH
• CO2 in the air dissolves in rainwater to form
carbonic acid – pH = 5.5 in unpolluted air
• Acid rain refers to very acidic rain with a
pH of 4.5 or less (Note: pH 4.5 is 10 times
more acidic than pH 5.5)
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Acid rain
• Burning of fossil fuels (e.g. …) releases
acidic oxides into the air, especially SO2
and nitrogen oxides (NOx)
• SO2 dissolves in rainwater to form
sulphurous acid (H2SO3) or reacts with
particles in the air to form sulphuric acid
(H2SO4)
• The resulting rain is very acidic and can be
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carried far by the wind
Effects of acid rain
• Reduces soil pH
• Phosphorus (P) binds to soil particles and is
unavailable to plant roots
• Al becomes soluble and poisonous and with
K, Ca and Mg is washed (leached) from the
soil into lakes and water supplies
Soil is impoverished and fish die in highly
mineralised water. Why?
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Effects of acid rain
• Erodes limestone buildings
• Causes breathing difficulties – irritates the
delicate lining of the lungs
• Inhibits chlorophyll formation and burns the
leaves of plants
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Effects of acid rain
Acid rain is a ‘trans-boundary problem’ i.e. it
is formed in one country but transported or
blown huge distances to another.
Norway ‘imported’ its acid pollutions from
the English Midlands and the Ruhr valley in
Germany.
• Ireland is lucky that the prevailing winds
are from the Atlantic and not from Europe.
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Dealing with acid rain
• Reducing the quantity of fossil fuels burned
• Using catalysts to treat chimney gases
(‘scrubbers’ are fitted to the insides of
chimneys)
• Catalytic converters fitted to modern cars
• Developing alternative ‘clean’ energy
sources
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Need to know
•
•
•
•
Define the term: Pollution.
State areas affected by pollution.
State mechanisms to control pollution.
Explain the difference between the terms
pollutant and pollution.
• Discuss the ecological impact of one human
activity.
Go to next topic
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Conservation
1.4.9 Human Impact on an
Ecosystem 2
Conservation
Conservation
Introduction
What is Conservation?
Benefits of Conservation
One Conservation practice from one of the
following areas:
• Agriculture
• Fisheries
• Forestry
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Conservation
Have you seen on of
these recently?
It is a Dodo and has
been extinct since
1681.
How did it happen?
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What happened to the dodo?
{Not examinable}
• In 1598 Portuguese and Dutch sailors were the
first people to live on the island of Mauritius.
• With them they brought pigs, dogs, rats and even
monkeys.
• They killed dodos for food and by 1681 (83 years
later) they were extinct.
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Conservation
• If you are connected to the internet click on the
link below to view a web page on the
Relationship of the Dodo Bird and the Calvaria
Tree {Not examinable}
http://geology.wcedu.pima.edu/~enicksin/new.html
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What is Conservation?
Conservation is the protection and wise
management of natural resources and the
environment.
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Benefits of Conservation
1. Existing environments are maintained
2. Endangered species are preserved for
reproduction
3. The balance of nature is maintained
4. Pollution and its effects are reduced
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One Conservation practice from
one of the following areas
Area
Agriculture
Fisheries
Forestry
Conservation Practice
Mixed farming, Crop rotation
Biological controls, Gene banks
Fishing Net size, Quotas, Re-stocking
Re-planting, Broadleaf/conifer mix
There is a need for continual monitoring of the
environment to ensure its protection and the
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wise management of its natural resources.
Agriculture
One Conservation practice from one of the
following areas is required:
Mixed farming
Crop rotation
Biological controls
Gene banks
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Mixed farming
What is mixed farming?
Farming system where both arable (crops) and
pastoral (livestock) farming is carried out.
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Conservation and Mixed Farming
• Animals provide manure and help to
maintain soil fertility and reduce the
quantity of artificial fertilisers used.
• Increases nutrients and soil water holding
capacity and improves soil structure.
• If rotations of various crops and forage
legumes are used, they replenish soil
nutrients
Go to next topic:
• Reduce soil erosion.
Waste Management
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• Recycling wastes prevents nutrient losses
Crop rotation
What is crop rotation?
Alternating the crops grown in a given field
from one growing season to the next.
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Conservation and Crop Rotation
• Different crops take different nutrients from
the soil, some crops restore particular
nutrients that others take away.
• Crop rotation can also interrupt the life
cycles and avoid the build up of pathogens
and pests that often occur when one species
is continuously grown.
Go to next topic:
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Waste Management
Biological controls
What are Biological controls?
Biological control is a method of controlling
pests (including weeds) and diseases in
agriculture that relies on natural predation,
parasitism or other natural mechanisms,
rather than introduced chemicals.
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Conservation and Biological Controls
• Ladybird larva eating
woolly apple aphids
Advantages:
• No chemicals used
• No chemical residues
left on plants
• No leaching of
chemicals into soil or
watercourses
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Conservation and Biological Controls
• Diagram illustrating the natural enemies of
cabbage pests
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Conservation in action in Agriculture
Conventional agriculture uses straw burning
and intensive tillage.
This has contributed to soil degradation
through loss of organic matter, soil erosion
and compaction.
These also have negative effects on the soil,
water and air qualities. Global climate,
wildlife and biodiversity are also affected.
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Is soil degradation serious?
• Soil degradation due to erosion and
compaction processes is probably the most
serious environmental problem caused by
conventional agriculture.
• About 10 million hectares of land are lost
per year for agricultural uses, due to soil
degradation processes
Note: 10,000,000 ha = 24,700,000 acres = 95,500
square miles. Ireland = 39,690 square miles
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A Dust Storm:
soil being blown away
Can you suggest what should be done?
Go to next topic:
• Stop straw burning
Waste Management
• Reduce the intensity of tillage
• Increase the amount of ‘set aside’ land
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Gene Banks
What are gene banks?
Gene banks are a means of preserving genetic
material, be it plant or animal.
In plants, this could be freezing cuttings from
the plant, or the seeds themselves.
In animals, this is the freezing of sperm and
eggs.
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Conservation and Gene Banks
This is one way scientists have of preventing
a gene family line from being wiped out.
In plants, it is possible to unfreeze the
material and sow it, however, in animals, a
living female is required for artificial
insemination.
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Conservation and Gene Banks
Artificial insemination of farm animals is very
common in today's agriculture industry.
It provides an economical means for a
livestock grower to breed their herds with
males having very desirable traits, e.g. good
beef quality, high milk yield, wool quality,
etc.
Go to next topic:
Waste Management
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Fisheries
One Conservation practice from one of the
following areas is required:
Fishing Net size
Quotas
Re-stocking
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Fishing Net size
What is net mesh size?
This refers to how large or small the openings
or spaces enclosed by the threads of a net
are.
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Conservation and Fishing Net Size
• The use of small-mesh nets can result in too
many young fish being caught
• Using larger meshed nets to allow the
young to escape, mature and reproduce
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Go to next topic:
Waste Management
Different types of nets
Square mesh – does
not alter its shape
under tension – allows
young fish to escape
Diamond mesh netting (left) –
closes under tension (right) and
prevents young fish escaping45
Fishing Quotas
What is a fishing quota?
A fixed proportion of the total allowable catch
allocated to each fishing nation.
This national quota allocation is further subdivided into quotas for specific areas,
seasons, fisheries or organisations, e.g.
producers' organisations.
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Fishing Quotas
Why have quotas?
Over fishing has reduced fish stocks at sea
Fish quotas (maximum amount allowed to be
caught) have been assigned to different
countries to ensure that enough fish are left
to replenish the stock.
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Conservation and Fishing Quotas
• Helps to prevent the extinction of a fish
species
• Gradually increases fish stock and helps to
re-establish populations
• Attempts to maintain fishing at highest
possible levels
Go to next topic:
Waste Management
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Re-stocking
What is the purpose of re-stocking?
To achieve a permanent increase in the
sustainable population of that species
Translocation of species into areas where they
have not naturally occurred is not
encouraged
Can you suggest why not?
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Conservation and Re-stocking
• Re-stocking attempts to maintain the balance
in the ecosystem
• Increases stocks for recreational fishing
Go to next topic:
Waste Management
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Forestry
Deciduous Forest
Coniferous Forest
Ground layer in
open Deciduous
Forest
Multi-layered
Forest
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Forestry
One Conservation practice from one of the
following areas is required:
Re-planting
Broadleaf/conifer mix
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Go to next topic:
Waste Management
Forestry Re-planting
• Ensures continued health and growth of
those forests that are periodically harvested
for timber.
• Allows foresters to choose the best species
or mix for the forest.
• Helps the forest regrow as soon as possible.
Replanting is now a common practice after
harvests and wildfire.
• Forests that aren't replanted after a natural
disaster, can take decades to re-establish. 53
Broadleaf/Conifer mix
• Conifers rapidly provide timber for
industry to replace imports
• Broadleaf trees also provides timber for
industry but at a much slower rate
• Broadleaf planting forms native
woodland and provides amenities,
wildlife habitats, adds to the landscape
and increases biodiversity
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Conservation in action in Forestry
• The selection and management of the tree
species has an effect on the flora and fauna
of the woodland
• Include local species of broadleaved species
in plantations
• Leave greater areas of open space within
plantations. This will encourage the growth
of an understorey of shrubs by increased
light penetration
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Conservation in action in Forestry
• Encourage the planting of woodland plots
with the greatest woodland edge
• Enhance the range of habitats of wooded
areas by leaving some mature and dead
wood; and increasing the number of water
courses and ponds
• Promote selective felling rather than
clearfelling as the dominant harvesting
technique
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Need to know
• Define the term: Conservation.
• Outline any one practice of conservation
from agriculture, forestry or fisheries.
Go to next topic:
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Waste Management
1.4.9 Human Impact on an
Ecosystem 3
Waste Management
Waste Management
What is waste management?
Waste management is the collection,
transport, processing, recycling or disposal
of waste materials, produced by human
activity, in an effort to reduce their effect on
human health or local aesthetics or amenity.
It also tries to reduce waste materials' effect
on the natural world and the environment
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and to recover resources from them.
Waste Management
• Urban rubbish is mostly dust, dirt, hair,
paper, food scraps, metal, glass and plastic.
• Traditional disposal has been to bury
rubbish in landfill sites or incinerate.
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Landfill operation
The area being filled has a rubberized landfill
liner is in place (exposed on the left).
This prevents leaching materials migrating
downward through the underlying rock.
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One of the following is necessary
Waste management in:
Agriculture
OR
Fisheries
OR
Forestry
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Waste Management in Agriculture
The main problems here are the waste
products from farms i.e.
• slurry
• silage effluent
• overuse / incorrect use of chemical
fertilisers and animal manures - excess of
these may enter watercourses and cause
algal blooms and eutrophication.
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Agriculture solution
Spreading the slurry on the land as a fertiliser.
This must be managed accurately in order to
maximise the value of the nutrients for crop
production and minimise their impact on the
environment.
Soil Nutrient Programmes aim to ensure
optimum crop yields and protect the quality
of water resources by avoiding pollution
from agriculture.
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Soil Nutrient Programme
The amounts of fertiliser applied can be
determined to ensure optimum yields
without causing environmental damage.
When devising a fertiliser programme the soil
fertility status must be known on foot of
regular soil testing.
There must be full recognition of all sources
of nutrients, both organic and inorganic.
Regular soil testing is very important to help
maintain a balance of nutrients in the soil. 65
Plastics on the farm
Plastic bags from fertiliser and plastic silage
wrap strewn all around a farm is becoming
a thing of the past.
Legislation on Producer Responsibility
Obligations ensures that the plastic must be
collected by the producers and dealt with
appropriately.
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Waste Management in Fisheries
Fish waste from fish landing and cleaning is a
major pollutant of marinas and harbours.
Accumulated fish waste leads to:
- Unpleasant odours
- Infestations of rats
- Maggots
- Low O2 levels in the harbour water due to
decomposition of waste by bacteria
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Waste Management in Fisheries
Solid organic by-products of the fishing
industry were going to landfill.
This has been greatly reduced by recent
legislation and dumping at sea is not an
option (EU regulation).
New projects are testing various methods of
management of fish wastes e.g. composting,
anaerobic digestion, recycling of protein/oil
etc.
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Animal feeds and Oils
Fish offal is converted to fish meal and this is
sold on as animal feed for e.g. chickens,
pigs.
Some oil is extracted from the waste during
the process and this is exported for further
refining and then used in health food
supplements.
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Ensiling (converting to silage)
The fish waste is chopped and liquefied, then
formic acid is added to it.
The resulting liquid silage can be used for
fertiliser.
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Fish waste Composting
Composting of fish waste is becoming more
popular now and it results in a soil
enhancer/fertiliser that is odour free, stable
and easily stored.
This will probably become the favoured
option for the industry in the near future.
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Waste Management in Forestry
• Leaves from coniferous trees should not be
allowed fall into rivers – make the water
acidic
• Chemicals and fertilisers should not be
allowed run off into waterways - algal
blooms and eutrophication
• When trees are harvested only bare poles
are removed so a lot of tree debris (called
brash) and the stumps are left behind
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Forestry solutions
• Waste Management in the forestry sector is
all based on recycling.
• When the trees are harvested brash and the
stumps are left behind.
• The stumps are sprayed with a urea-type
compound which speeds up the
decomposition process
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Forestry solutions
• The brash is either left to decompose on the
forest floor or collected and sold as a fuel
source.
• In some of the larger sites the sawdust and
debris is sold on for conversion to
fibreboard e.g. MDF
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Problems with Waste Disposal
• Availability of suitable landfill sites
• The toxic or polluting content of fumes from
incineration (CO2, other acidic oxides and
dioxins – produced from burning plastic)
• Decaying waste produces methane gas which
contributes to the “greenhouse gases”
• Harmful substances may leak into
groundwater supplies (wells, lakes, reservoirs)
• Plants and animals in rivers and lakes are
killed through direct poisoning or
eutrophication
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Possible solutions
• Lifestyle changes and education
programmes for all ages are needed to alter
the attitudes to littering and waste
minimisation and disposal
• Use micro-organisms to degrade the rubbish
and produce fuel pellets
• Reduce the use of paper and recycle more
paper
• Biodegradable materials (e.g. paper bags)
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should be used in place of plastic ones.
Possible solutions
• Tax has been placed on plastic bags in
shops
• Rubbish sorting at source makes disposal
more efficient e.g. householders
could separate metals, paper, plastic, glass
for recycling and ‘vegetable’ waste for
composting
• Increase incineration temperatures to avoid
dioxin production and fit catalytic scrubbers
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inside chimneys
Suggestions for waste
minimisation
• Reduce – use less, minimise waste.
• Re-use – use again, without changing but
maybe for a different purpose.
• Recycle – change, recover some material
and use again.
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Role of micro-organisms in
Waste Management
Composting is an aerobic process during
which micro-organisms decompose organic
matter into a stable substance called
compost which recycles all the nutrients
required for plant growth.
Since it is aerobic the organic waste mixture
must be turned and loosened to allow air
into it.
This increases the size and number of air
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pores.
Micro-organisms in Waste
Management
Fungi break down the ‘tougher’ materials in
the waste such as lignin and cellulose.
Their filamentous structure penetrates the
composting material and helps to improve
aeration and drainage in the compost heap.
Temperatures within a compost heap can
reach 70°C as the bacteria and fungi work to
breakdown the material.
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Micro-organisms in Waste
Management
Pathogens e.g. human viruses and infectious
bacteria, are unable to survive at such high
temperatures
Because the temperature at the outside of the
heap is cooler than in the centre it is
important to mix the pile to ensure
maximum pathogen and weed seed kill.
If the pile is unventilated the temperatures rise
too high and the composting microorganisms themselves are unable to survive.81
Vermicomposting
This is another method of recovering the
nutrients from organic waste, uses worms to
consume the food waste and utilizes the
worm castings as compost.
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Role of micro-organisms in
Pollution Control
Composting can reduce environmental
pollution caused by disposal of organic
wastes in landfills and streams or by
incineration.
Bacteria and fungi break down organic matter
into compost that recycles all the nutrients
required for plant growth.
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Need to know
• State problems associated with waste
management & disposal.
• Explain the importance of waste
minimisation.
• Explain the role of microorganisms in waste
management and pollution control.
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