Biology Form 4 Chapter 9.1

7/22/2019 Biology Form 4 Chapter 9.1

1/47

Chapter 9Endangered Ecosystem

9.1 Human Activities thatEndanger the Ecosystem


2/47


3/47

What is Deforestation?

The extensive removal of trees fromforests.

Vast area of forests are cleared foragriculture, development and loggingactivities.


4/47


5/47

Regulating worlds climate.

Functioning as habitat of various flora andfauna.

Housing plants which produce food andpharmaceutical products.

Regulating the amount of Carbon Dioxide

and Oxygen through photosynthesis. Serving as water catchment areas.


6/47


7/47

How does it happen?

When it rains for a long period of timeduring rainy seasons, the top layer of soil

loosens and slides down. Thus, Landslideoccurs.


8/47


9/47

The loss of stability of soil is due todeforestation.

Clearing of trees causes the loss of tree leaves

to protect soil from the impact of raindrops.It also causes the loss of tree roots to hold thesoil in place.

Soil is exposed directly to the force of rain.

Heavy rainfall easily washed away the toplayer of soil, causing Soil Erosion.


10/47

The eroded soil is carried by water and may bedeposited into rivers.

During heavy rains, rainwater flows quickly intoriver because there is not retention of water byplant roots, as well as water catchment areas.

Due to silting in the rivers, the water flow becomesblocked. Hence, water flows inland and causes flashflood in low area.

Flash Floods cause loss of lives and properties.

Soil erosion also leads to depletion of minerals forthe land. The land cannot be used for cultivation.


11/47


12/47

Deforestation leads to the loss of habitats formany species of F&F.

This will cause an increased rate of

extinction of plants and animals. As a result,it reduces the biodiversity & the source offood and valuable medicines for humans.


13/47

When many trees are destroyed, it reducesrainfall, transpiration rate and rate of usingCarbon Dioxide during photosynthesis by plants.

Clearing & burning of forests also release vast

amount of greenhouse gases, e.g. Carbon Dioxideinto the atmosphere.

Deforestation contributes 20%-30% of carbondioxide in atmosphere every year.

Carbon dioxide prevents heat from escaping theatmosphere. Thus, the level of carbon dioxideincreases and global temperature also increases,which results Greenhouse Effect and GlobalWarming.


14/47

When forests are cleared, the areas becomehotter and drier causing Climatic Changesand changes in wind patterns.


15/47

Excessive use of land for farming leads toinfertile land.

Use of inorganic fertilisers such as nitrates

and phosphates leads to Eutrophication.


16/47

BOFF leads to an increase in the amount ofcarbon dioxide in the atmosphere.

As a result, this leads to Greenhouse Effect

and Global Warming.

BOFF and open burning can also cause AirPollution.


17/47

Industrial plants discharge industrial wasteand heaved waste water causing WaterPollution and Thermal Pollution.

Toxic gases released by industries contributeto Air Pollution.


18/47

Pollutions


19/47

What is pollution?

An undesirable change in chemical, physicalor biological characteristics of natural

environment. Environment is polluted by pollutants.

Pollutants may be toxic substances e.g.Pesticides, or natural constituents ofatmosphere e.g. Carbon Dioxide. They mayaffect the soil, rivers, seas, or theatmosphere.


20/47


21/47

Occurs when pollutants are released into theair.

Will affect human respiratory system,

human lives and other living organisms.


22/47

THE SOURCES OF AIR POLLUTIONAND THE EFFECTS

Carbon monoxide

Reduces the ability of the blood to transportoxygen

Lead to brain damage and death

Carbon dioxide

Affects respiration

Acid rain-damage buildings

Greenhouse effect and global warming


23/47


Nitrogen Monoxide and Nitrogen dioxide

Damages lung tissues

Irritates eyes Lowers the bodys defence

Affects enzymes functions

Acid rain-reduces the pH of soil,lakes andrivers,destroys buildings


24/47


Sulphur dioxide

Irritates and damages eyes, air passage andlungs

Causes coughing and wheezing

Affect function of enzymes

Reduces the growth of plants Causes acid rain


25/47


Fine particulate matter

Irritates the eyes and respiratory tract

Contributes to haze that can cause bronchitisasthma attack, conjunctivitis, sore throatand others.

Can cause mutation

Soot can dirty and darken buildings

Deposits on leaves and darken the vegetable


26/47


Lead (combustion of fossil fuels)

Reduce the sensitivity of the hands and feetcoordination

Retards mental development in children

Disrupts bodys ability to produce new cells

May damage kidneys


27/47


Hydrocarbon

affects growth

Causes cancer Causes mutation


28/47

Acid rainCauses

Combustion of fossil fuels produces sulphur oxideand oxides of nitrogen

Forms acids when dissolve in water

Acids fall as acid rain

Oxide of nitrogen combine with water to formnitric acid

Sulphur dioxide combines with water vapour toform sulphuric acid.


29/47

Acid rainSolution

Use scrubbers to clean emissions fromindustrial plants

Use catalytic converters to convertharmful emissions from exhaust pipes


30/47

Acid rainEffects

Corrodes metals, marble, rubber, plastics andother materials

Leaching minerals such as calcium from the soil,

causing infertile soil Release ions of heavy metals such as lead which

may contaminate the water

Destroys plant tissues and damages plant roots

Reduce the pH of the soil making it unsuitablefor farming


31/47

Air Pollution Index (API)

Used as a measure of air quality

Calculated based on concentrations of fiveparticles and harmful gases in atmosphere.

API Status

0-50 Good

51-100 Moderate

101-200 Unhealthy201-300 Very unhealthy

301-500 Hazardous

Above 500 Emergency


32/47

Water PollutionCauses:

Discharging industrial, domestic andagricultural waste

Discharging sewage onto water source


33/47

Pollutants & SourcesNitrates & Phosphates Fertiliser from farm, agricultural run-off, sewage

effluent

Pesticide & Herbicide Farms, agricultural run-off

Detergents Domestic sewage

Oil & Grease Oil spills, industrial effluent

Suspended solids &rubbish

Domestic wastes, industrial effluent

Heavy metals Industrial plants

Electronic factories

Mining industries

Factories which produce/ process paints,

metals, ink

Chemical & Radioactive

waste substances

Nuclear power station, research laboratory

Microorganisms Untreated sewage, human faeces, animal

wastes


34/47

Eutrophication

What is Eutrophication?

- a natural process whereby an aquaticecosystem becomes enriched with nutrients

causing an excessive growth of aquaticplants.

Nutrients come from:

Fertilisers

Sewage treatment

Animal wastes


35/47

Eutrophication

The increases nutrients in river, lakes andstreams promote rapid growth of algae.

Excessive growth of algae is called Algal

Bloom.


36/47

How Algal blooms endangerthe ecosystem 1

The densely populated algae cover the watersurface and block sunlight. Unable to carryout photosynthesis, the aquatic plants die.

When these plants die, aquatic animals losetheir food sources and habitats. Hence, thefood chain and ecosystem change

Algae also reduces the level of dissolvedoxygen in water


37/47

How Algal blooms endangerthe ecosystem 2

When algae and other aquatic organisms die,decomposing organisms esp. saprophyticorganisms use up oxygen to decompose thedead organic materials.

This reduces the oxygen content in thewater.


38/47

Eutrophication

Eutrophication increases the BOD value inwater.

Higher the BOD value, the more polluted the

water as dissolved oxygen level decreases.


39/47

Eutrophication

Depletion in oxygen results in an increase inBiochemical Oxygen Demand (BOD)

Eutrophication increases the BOD value in

the water. BOD refers to the amount of oxygen utilised

by microorganisms to oxidise all organicmatter in one litre of water.

The higher the BOD value, the more pollutedthe water as the dissolved oxygen leveldecreases.


40/47

Water Quality Index (WQI)

WQI is used by the Department ofEnvironment to indicate the quality ofwater.

WQI Pollution level Class92.8-100.0 Very clean 1

76.6-92.8 Clean 2

52.5-96.6 Slightly polluted 3

29.7-52.5 Polluted 4< 29.7 Very polluted 5


41/47

Thermal Pollution

Occurs when there is :

an increase in temperature of water sources

Excessive heat in the environment


42/47

Thermal PollutionCauses

Hot water discharged from industrialprocesses, cooling towers of power stationand reactor plants- can increase rivertemperature by 10 Degree Celcius

Radiation of heat from glass building


43/47

Thermal PollutionEffects

Reduce the level of dissolved oxygen inwater. This affects the aquatic organisms.

Cause some aquatic organisms to die because

they can only survive in a certaintemperature. Some also move away. Thisaffects the food chain and also the entireecosystem.

Encourages Algae to grow rapidly whichleads to high BOD value.


44/47

Noise Pollution

Occurs when our daily lives are disturbed byhigh level of noises.

WHO recommends a noise level of not more

that 55 dB (decibels). When surrounding noise level reaches 80 dB

or more it causes discomfort and affects thehuman health.


45/47

Noise PollutionSources

Vehicles

Jet planes

Construction sites Entertainment outlets

Machines


46/47

Noise PollutionEffects

Headache

Emotional disturbance

Mental disturbance Deafness


47/47

Chairyl

Idee Shu.T

Prepared by,

Documents

Biology Form 4 Chapter 9.1