HUMAN ACTIVITY THAT ENDANGERED AN ECOSYSTEM AND ITS IMPACT.

Deforestation and its effects.

1. The rapid destruction of woodlands or the removal of trees from forests is known as deforestation.

2. Every year, vast areas of forests are cleared to make way for agriculture and development.

3. Tropical rainforests have important ecological roles;a) Rainforest are the oldest ecosystem on Earth and house almost half of the flora

and fauna of the worldb) They contain many unique species which provide food, medicine and other

biological products.c) Rainforests regulate climate by influencing winds, rainfall, humidity and

temperature patterns.d) Rainforests are also called the ‘carbon sink’ of the Earth because they absorb vast

amounts of carbon dioxide during photosynthesis and at the same time release oxygen into the atmosphere.

e) They also serve as water catchment areas.4. Despite their importance, it has been estimated than more 50 million acres of rainforest

are destroyed or seriously degrade every year.5. In general, deforestation result in;

a) Soil erosionb) Flash floodsc) Landslided) Disruption to the carbon and nitrogen cyclese) Severe climatic changesf) The loss of biodiversity

1

Deforestation causes soil erosion landslide and flash floods.

1. Without paper development and planning, a land stripped of its vegetation is subject to soil erosion. Soil erosion is the removable and thinning of the soil layer due to physical and climatic processes, such as high rainfalls.

2. The absence of plant roots systems makes the soil structure unstable.3. When there are heavy rains for a long period of times, the top layer of the soil crumbles

and this leads to landslide on steep hill slides.4. The eroded soil is then carried by moving water and deposited at the bottom of the rivers.5. This, together with depletion of water catchment areas, causes flash floods during the

rainy seasons.6. Soil erosion causes he land to be depleted of minerals and natural resources, making land

infertile.

Deforestation results in the loss of biodiversity.

Deforestation has a devastating effect on the biodiversity in tropical rainforests.The destruction of millions of hectares of forests by human activities means:

a) The removal of the bases of numerous food websb) The loss of habitats of many species of flora and faunac) The extinction of countless species and varieties of plants and animals. The extinction

of flora and fauna species reduces the biodiversity. Biodiversity can be a rich sources of food and priceless medicines to mankind.

Deforestation disrupts the carbon and nitrogen cycles.

1. The removal of plants in the rainforests disrupts the natural cycle of nutrients.2. The level of atmospheric carbon dioxide rises as less carbon dioxide in the air is removed

by a plant during photosynthesis.3. The level of atmospheric oxygen drops as less oxygen is released by plants during

photosynthesis.4. The recycling of nitrates and other ions slows down.5. Three roots bind soil particles together, and the tree canopy reduces the force of rains

beating down on the soil.Deforestation,therefore,causes the loss of nutrients through leaching and run-offs.

2

Deforestation causes climatic changes.

1. Deforestation disrupts the normal weather patterns, creating hotter, drier weather and causing global climatic changes.

2. The removal of trees reduces transpiration, rainfall and the rate at which plants absorb carbon dioxide from the atmosphere during photosynthesis.

3. This leads to increase in the carbon dioxide level in the atmosphere. High levels of carbon dioxide prevent heat from escaping from the atmosphere. This is known as the greenhouse effect which is believed to lead to global warming.

4. Forest clearing and burning of woods result in air pollution and release more carbon dioxide into the atmosphere.

5. Burning of trees in the tropics adds about 25% more carbon dioxide to the atmosphere.

Burning of fossils fuels and its effects

1. The burning of fossils fuels adds about 75% of carbon dioxide to the atmosphere.

An increase in carbon dioxide level is associated with the greenhouse effect and global warming.

Intensive farming and its effects

1. Excessive use the land for intensive farming decreases the space and resources available for other species.

2. In extensive farming, farmers often use inorganic fertilisers, which contain nitrates, phosphates and potassium ions, to improve crop yields.

3. Since nitrate and ammonium ions are highly soluble, they do not remain in the soil for long and are quickly leached into the surrounding rivers and lakes.

4. This leads to eutrophications.Eutrophication is discussed later in the section on water pollution.

The effects of an increase in domestic waste & industrial.

1. An increase in human population generates an increase in both domestic and industrial waste.

2. The dumping of waste in landfills poses a great danger to living organisms as toxics substances and other pollutants from the dumpsites leak into the ground and eventually pollutes the nearby water resources.

3

POLLUTION.

1. Pollution can be defined as any undesirable change in the physical, chemical or biological characteristics of the natural environment. It is the result of harmful substances or energy released through human activities.

2. There are four types of pollution:a) Airb) Waterc) Thermald) Noise pollution

Air pollution.

1. Burning of fossil fuels is the main sources of air pollution. Fossil fuels are burnt in power stations using coals, petroleum and natural gases, in domestic and industrial boilers, and in the internal combustion engines of vehicles.

2. When fossil fuels are burnt, the elements in the fuels are oxidised, forming various air pollutants.

3. These include carbon dioxide(CO2), sulphur dioxide(SO2), oxides of nitrogen(NO2), and fine particulate matter.

THE SOURCES AND EFFECTS OF AIR POLLUTANTS.

POLLUTANTS SOURCES EFFECTS SOLUTIONSCarbon monoxide Colourless,

odourless gas

Incomplete combustion of fossil fuels

The exhaust of vehicles

factories

Health: combines readily with haemoglobin and

effects the transport of oxygen to body cells

impairs alertness, causes fatigue and headaches

4

POLLUTANTS SOURCES EFFECTS SOLUTIONSSulphur dioxide pungent,

colourless gas sulphur dioxide is

formed when sulphuric compounds is react with oxygen during combustion

Combustion of fossil fuels, particularly in heat and power generation facilities.

Volcanic gases Large industrial

boilers Factories

Health: Irritates the eyes Damages respiratory passages Causes bronchitis Causes wheezing, a shortness of

breath and coughing Causes asthmatic attacksClimate: Combines with rainwater to form acid

rainAgriculture: Contributes to acid rain which

damages photosynthetic tissues Acid rain lowers pH of soil, rivers and

lakesBuildings: Acid rain corrodes iron, limestone and

stonework, and destroys buildings

Use low sulphur content fuels.

Clean up from power stations and factories with scrubbers.

Oxides of nitrogen Nitrogen

monoxide Nitrogen dioxide

Vehicles exhaust Action of bacteria

on fertilisers Combustion of

fossil fuels Factories

Health: Irritate lungs, nose, throat and eyes Cause respiratory infections Cause bronchitis Dissolve in rainwater to form acid rainAgricultural: Contributes to acid rain which lowers

pH of soil, making it unsuitable for cultivations of crops

Damages leaves and rootsBuildings:

Clean up emission from car exhaust by installing catalytic converters to turn oxides of nitrogen into harmless nitrogen gas.

Acids rain corrodes metal and destroys stonework on buildings.

LeadLead compounds are added to petrol to prevent the inefficient burning of the petrol-air mixture.

Combustions of fossil fuels

Vehicles exhaust fumes

Health: Retards mental development and

damages the liver Can result in coma or death

Use unleaded petrol

Carbon dioxideAn acidic, colourless and odourless gas

Open burning Combustions of

fossils fuels

Health: Affects respirationClimate: Leads to greenhouse effect and global

warming Results in an increase in the

atmospheric temperature Climatic changes

Reduce the use of fossil fuels

5

Fine particular matter A complex

mixture of very fine liquid droplets or solid particles in the air such as dust, smoke, and exhaust fumes.

Smoke contains tiny carbon particles called soot

Haze is formed when smoke, dirt and particulate matter combine with water vapour in the atmosphere.

When there is no wind, smoke may be wapped by fog to form smog.

Incomplete combustion of fossil fuels, for example bonfire, open burning, the burning of oil wells and the burning of dried paddy stalks.

Motorised vehicles exhaust

Quarries, sawmills and asbestos factories

Health: Irritate the eyes, nose and lungs Damage the respiratory passage and

lungs Haze can cause conjunctivitis, sore

throats, influenza, asthma and lead to bronchitis.

Dust from quarries, sawmill and asbestos factories can cause lung diseases.

Haze leads to reduced visibilityAgriculture: Smoke particles (soot) deposit on

leaves and block stomata. This prevents gaseous exchange.

Both lower the photosynthetic rate of plants which subsequently reduces crop yields.

Climate: Contribute to the formation of haze

and smog Smoke and haze can reduce visibility.Buildings: Soot darkens buildings.

More efficient burning of fuels in well-designed furnaces.

Stop open burning.

6

Acid rain.

1. Causes of acid rain.a) The combustion of fossil fuels (coal, air, and gas) in power stations, factories,

domestic boilers and internal combustion engines releases large quantities of sulphur dioxide and oxides of nitrogen.

b) Both sulphur dioxide and oxides of nitrogen combine with water vapour in the atmosphere to form sulphuric acid and nitric acid respectively.

c) Then they fall to Earth as acid rain

d) Rain is naturally acidic, with a pH of about 5.6. this acidity is due to the carbon dioxide in the air, which dissolves in rain to form carbonic acid.

e) However, the pH of acid rain is less than 5.0.

2. Effects of acid rain.a) Agricultural:

the soil becomes very acidic and un suitable for the cultivation of crops

Acid rain causes the leaching of minerals such as potassium, calcium and magnesium. This effects the growth of crops.

b) aquatic ecosystem:

Acid rain causes insoluble aluminium ions to accumulate in lakes and rivers. The concentration of aluminium ions eventually reaches a toxic level which can kill aquatic organisms such as fish and invertebrates.

Increase acidity in the aquatic ecosystems also kills phytoplankton which can changes the food chain.

Photosynthetic tissues are destroyed. Plant leaves turn yellow and fall off. The roots are damaged and cannot absorb minerals.

c) Health:

Acidic soil releases the ions of certain heavy metals such as cadmium, lead and mercury which may contaminate the supply of drinking water.

d) Buildings:

Metal railings and bridge corrodes

Limestone, stonework and marble monuments are eroded due to chemical weathering.

3. Acid rain can be reduced bya) Cleaning up emissions from power stations and industrial plants with scrubbers. This

process involved the spraying of water to trap pollution.

b) Cleaning up emissions from vehicles exhausts through the use of catalyse converters. The pollutants react with one another in the catalytic converters to produce less harmful products.

7

Water pollution.

1. Water sources are the most easily pollute as they most affected by human activities.2. Industrial, domestic and agricultural activities produce waste which pollutes water.3. The sources of water pollution are summarised below;

SOURCES COMPONENTS/POLLUTANTS & THEIR EFFECTSAgricultural run-offs and waste from oil palm and rubber processing mills.

Nitrates and phosphate (in fertiliser) Excess nitrates and phosphate lead to eutrophication

Herbicide and pesticide residues Accumulation of pesticides and herbicides may have toxic

effects on organisms in the water and humans if the water and humans if the water is used as drinking water.

The pesticides levels accumulate as they pass through the food chains

High concentration of pesticides may accumulate in the tissues of final consumers which are mainly carnivores. The pesticides may kill the carnivores or may effect their metabolism.

Studies have also shown that pesticides have leds to lower sperm counts, decrease ovulation, the inability to conceive and birth defects.

Untreated sewage-consisting mainly of human faeces and domestic waste

Suspended solids Reduced light penetration If suspended solids are biodegradable, they can be decomposed

by microorganisms and this process requires a high demand for oxygen

Domestic waste includes detergents and food waste.

Detergents ‘hard’ detergents create foam which reduces the supply of

oxygen to organism living in water ‘soft’ detergents are biodegradable but may contain high levels

of phosphate which can lead to eutrophication

Animal waste from farms

Microorganisms such as bacteria and protozoa If the water is used for drinking, it must be properly treated or it

may cause water-borne diseases such as cholera.

Effluents from industries

Highly toxic and accumulate in the organism via food chains Mercury can cause acute nervous disorders in humans

Underground pipes Lead Can accumulate in the tissues of living organisms Can impair the mental ability of children

8

Eutrophication .

1. Eutrophication is the artificial nutrient enrichment of an aquatic system with organic material or inorganic nutrients, causing an excessive growth of aquatic plant life.

2. Eutrophication can be caused by:a) The leaching of inorganic fertilisers, especially nitrates and phosphate, from

agricultural landsb) The input of untreated sewage as well as discharge from sewage treatment plantsc) Run-offs containing animal waste from pastures and farmlands into lakes, rivers or

ponds.

Thermal pollution.

o Causes of thermal pollution

1. Hot water is discharge into nearby lakes and rivers from the effluents of industrial processes and the cooling towers of electrical power station which use water as a cooling agent.

2. The excess heat that is released into the environment leads to thermal pollution.3. The thermal pollution causes the temperature in the body rise above the normal value. The

increases in temperature can be between 5’C and 10’C.

o Effects of thermal pollution

1. Water temperature can affect the level of dissolve oxygen. When the temperature of water increase, oxygen becomes less soluble in water.

2. Algae, an increases in temperature actually encourages their rapid growth which, in turn, leads to a higher BOD value.

3. If the temperature increases continues over a long period, this may result in permanent changes in the species composition of the aquatic ecosystem.

Noise pollution .

9

o Cause of noise pollution

a) Noise pollution comes from:

i. Cars

ii. Motorcycles

iii. Aeroplanes

iv. Constructions sites

v. Agricultural

vi. Industrial machinery

o Effects of noise pollutiona) Excessive exposure to high levels of noise is considered a health risk because noise

can contribute to stress-related problems such as high blood pressure, coronary diseases, ulcers, depression and headaches.

b) Loud noise can cause an arousal response in which a series of reactions occurs in the body.

c) Adrenaline is released into the bloodstream. A persons’ heartbeat rate, blood pressure, and respiration rate are likely to increases. The blood vessels constrict and the muscles become tense.

d) It is possible that repetitive or constants exposure to noise can be harmful to health.

10

THE GREENHOUSE EFFECT AND THE THINNING OF THE OZONE LAYER.

THE GREENHOUSE EFFECT.

DEFINITIONThe greenhouse effect is an effect in the atmosphere as a result of the present of certain gases, called the greenhouse gases. A greenhouse is used to grow vegetables and plants in temperature climates, especially during winter. A greenhouse is design to trap solar energy. Sunlight penetrates the glass roof of a greenhouse to warm the soil. However, the heat given off by the soil cannot pass through the glass, so it remains inside to warm the air. This means that the heat from the sun is trapped inside the greenhouse and this keeps the plants warm throughout winter.

CAUSES AND EFFECTS

1. The combustion of fossil fuels (coal, petroleum, and natural gases) and other human activities such as increases deforestation and industrial production are the primary reasons for the increases concentration of atmospheric carbon dioxide.

2. As the concentration of greenhouse gases rises, the greenhouse effects increases, trapping more heat in the atmosphere and raising the average temperature on Earth.

3. This overall rise in the average temperature of the atmosphere is known as global warming.

4. The effects of global warming:a) Occurrence of floods

As the mean temperature rises, the polar ice caps and glaciers melt. This causes a rise in sea levels. A rise in sea levels causes low-lying areas to be flooded.

b) Occurrence of drought Global warming increases the frequency of drought. The land becomes dry and infertile This leads to a drop in crop yields.

c) Climate changes Global warming leads to changes in wind direction and the distribution of

rainfall. As a result agricultural activities are affected. Global warming causes weather patterns to change. This effect the distribution of

species in certains regions.d) Spread of diseases.

With warmer climates, pests and vectors may spread to new areas.

11

WAYS TO REDUCE GREENHOUSE EFFECTS

1. Reduced the burning of fossil fuels to conserve energy.2. Develop alternative sources of energy such as wind, solar and geothermal energy in the

Earth.3. Replants trees which have been cut down4. International cooperation as well as individual action is needed to lessen the effects of

global warming.5. International treaties that bind countries to their commitment of limiting and reducing the

amount of carbon dioxide as well as other greenhouse gases which are released into the atmosphere must be implemented.

12

THE THINNING OF THE OZONE LAYER.

DEFINITION

1. The ozone layer is a region in the stratosphere, between 20-25 kilometres above the surface of the Earth.

2. The ozone layer contains high concentrations of ozone molecules (o3) that absorbs ultraviolet (UV) radiation and shield organisms from its damaging effects.

3. This layer of ozone shields us from excessive ultraviolet radiation from the sun.

CAUSES OF THE OZONE DEPLETION

1. The destruction of the ozone layer is mainly due to the increasing levels of chlorofluorocarbons (CFC) in the atmosphere.

2. CFCs are very actives chemical that contains chlorine, carbon and fluorine.3. CFCs are used as coolants in air conditioners and refrigerators, propellants in aerosol

cans and foaming agents in the making of Styrofoam packaging.4. CFCs are extremely stable and can remain in the environment for as long as 75 to 100

years.5. Once in the stratosphere, CFCs are broken down by ultraviolet rays.6. As a result, the highly reactive chlorine radicals are released.7. These chlorine radicals break down the ozone molecules (O3) in a chain reaction.

THE EFFECTS OF OZONE DEPLETION

1. The consequences of ozone depletion are very severe. Prolonged exposure to ultraviolet radiation can lead to higher risks of Skin cancer, such as melanoma. Ultraviolet radiation cause mutations that leads to

skin cancer Cataracts Sunburst

2. Ultraviolet radiations weaken the immune system and the ability of the body to resist infectious diseases.

3. Ultraviolet radiation reduces nutrient contents and crops yields of plants such as soya beans and peas.

4. Ozone depletion also leads to an increase in the temperature on Earth.

13

5. Leaf cells and chlorophyll are easily damaged by the ultraviolet rays. This lowers the rate of photosynthesis and reduces crop yields.

6. Ultraviolet rays kill microorganisms and phytoplankton that are at the bottom of the marine food chain, the base on which most of the world’s population depends for protein.

7. High levels of ultraviolet radiation can damaged the eggs of certain amphibians.

WAYS TO REDUCE OZONE DEPLETION

1. Reduced or stop using of CFCs.2. Replace the use of chlorofluorocarbons (CFCs) with

hydrochlorofluorocarbons(HCFCs) and hydrofluorocarbons (HFCs). Unlike CFCs, these gases break down in the atmosphere and return to Earth in the form of rainwater.

14

Ways to ensure a balanced and stable ecosystem is maintained.

BIOLOGICAL CONTROL

1. Biological control is the use of natural predators to control the population of pests species.

2. Biological control is better than chemical control which involves the use of pesticides. This is because; The effects of pesticides can be persistence and remain in the environment for long

periods The concentration of pesticides is amplificated as they pass through food chains

(bio-magnification). As a result, high concentration of pesticides may accumulate in the tissues of final consumers. These pesticides can be toxic affect the metabolism of the organisms.

Pests develop resistance. Hence, a larger amount of pesticides may now be required to produce a similar effect.

The costs of pesticides in high. The extensive use of pesticides pollutes the environment.

IMPLEMENTATION OF LAWS

1. The government has implement laws to protect and govern biological resources and the environment.

2. Many laws and regulations are design to control pollution which are effects the quality of land, air and water.a) The environmental quality act, 1974, 1989b) The natural forestry act,1984c) The protection of wildlife act, 1972

3. It is hoped that these legislation will protect the quality of the environment from irresponsible person or companies.

15

THE USE OF TECHNOLOGY.

1. Install catalytic converters in vehicles to clean up exhaust emissions and convert the harmful gases released during the combustion of fossil fuels to less harmful products.

2. Use unleaded petrol to reduce the emissions to lead into the environment.3. Treat sewage in sewage treatment plants before it is discharge to reduce water

pollution.4. Treat toxic waste from factories before it is discharge into the environment.5. Use microorganism to clean up the environment. For example, certain bacteria are

used to break down oil spills at the sea.6. Develops hydrogen-based fuel – cell vehicles to reduce the burning of the fossils

fuels.

THE EFFICIENT USE OF ENERGY.

1. Reduce the burning of coal, petroleum, and other fossil fuels.2. Substitute natural gas for coal at power plants.3. Improve fuel efficiency in vehicles – use cars that runs on energy – efficiency

engines.4. Use a cleaner fuel by reducing the content of sulphur in diesel and switching to other

gas. 5. Improve energy efficiency in factories6. Use more hybrid cars which combine electric and gasoline engines.

THE USE OF RENEWABLE ENERGY.

1. Fossil fuels are non-renewable energy sources. Hence, there is a need to look for alternative sources of energy.

2. Renewable energy is energy flow that occurs naturally in the environment and can be harnessed for the benefit of humans.

3. Examples of renewable: Solar energy which can be converted into electricity and used in heating Wind energy which is used to operate windmills to pump water for the irrigation of

crops. Flowing water which is used to generate hydroelectric power. Wave energy Geothermal energy

16

Biomass energy which is produced when decomposing organic matter releases a gas consisting of 50% methane. This biogas can be produced on a large scale in composting plants and also by decomposing organic matter in landfills. The biogas released can be collected and used as fuels for various purpose such as heating or generating electricity.

Palm oil fuels Palm oil can be converted into methyl ester which is used as fuel. Biodiesel from crude palm oil is an environment friendly alternative to petroleum diesel. Biodiesel can meet approximately 17% of the country energy requirements and thereby reduce the country’s dependence on petroleum.

Gasohol which is the conservation of energy in biomass.

PRESERVATIONS AND CONSERVATION OF SOIL, WATER, THE FLORA AND FAUNA OF FORESTS, AND MANGROVE SWAMPS.

1. Preservation involves efforts to protect an ecosystem so that the natural resources are utilised in a sustainable manner and that the equilibrium of the ecosystem is maintained.

2. Conservation involves efforts to returns an affected ecosystem to its natural equilibrium.

3. Sustainable agricultural development is the effective use and preservation of soil to ensure continuous agricultural production.

4. Good farming techniques will prevent erosion and soil depletion.5. Good agricultural practices include

a) Crop rotationb) Contour farmingc) Controlled grazingd) Planting cover cropse) The appreciated use of fertilisersf) Effective drainage and irrigation

6. Establish of forests reserves to prevent the destruction of existing forests and maintaining the equilibrium of the ecosystem so that the quality of the environment is preserve,

17

EDUCATION ON THE MANAGEMENT OF RESOURCES

1. The public must educate on the concept of the 4Rs. 4Rs stand for recycle, reuse, reduce and recover.

2. Reuse means use things such as old plastics containers and bottles again for other purposes instead of throwing them away.

3. Reduces means cutting down on the use of materials. For examples, the use of plastic bags which are non-biodegradable should be reduced. Instead, use paper bags which are biodegradable and environment friendly.

4. Recover means to hardness heat energy from the burning of materials or refuse in factories or incineration plants. This heat energy can be used to generate elecricity.

18