CHAPTER 9:ENDANGERED ECOSYSTEM

9.1 Human Activities that Endanger an Ecosystem

Learning Objectives

Evaluating human activities that endanger an ecosytem

Uderstanding the greenhouse effect and thinning of the ozone layer

Realizing the importance of proper management of development activities and the ecosystem

Human activities that threaten an Ecosystem

Human activities that threaten an Ecosystem

Human activities that threaten an Ecosystem

• The world’s population has grown to over 6 billion today, so conflicts arise between the need to meet the immediate human demands in the short term and the need to protect and conserve ecosystems from long-term damage

• Most of the problem related to the environment are the results of human activities and human interference with the ecosystem function

Human activities that threaten an Ecosystem

• Human activities, if unplanned and mismanagement of ecosystems result in various environmental problems; air and water pollution, the greenhouse effect, global warming and the depletion of natural resources

• These problems bring about negative effects that increasingly threaten the economic resources, health and survival of ecosystem

Human activities that threaten an Ecosystem

Human activities that have undesirable effects on the environment

Deforestation Burning of fossil fuels Overuse of fertilisers in intensive farming

Dumping of domestic and industrial waste

Leads to

Leads to

Leads toLeads to

• Soil erosion• landslides• flash floods• climatic changes• lost of

biodiversity• greenhouse

effect

• greenhouse effect• global warming• air pollution

• eutrophication• water pollution

• water pollution

Deforestation

Important roles of tropical rainforests:

The oldest ecosystem on the Earth and home to almost half of the world’s flora and fauna.

Contain many unique species which provide food, medicine and other resources for human.

Regulate the world climate.

Act as a carbon sink of the Earth because they absorb vast amount of carbon dioxide during photosynthesis and at the same time release oxygen into the atmosphere.

As water catchments areas.

The impacts are:

Soil erosion

Flash flood

Landslides

Changes in the recycling of materials

Severe climatic changes

The loss of biodiversity

Deforestation

Deforestation

Deforestation

Loss of habitat Loss of biodiversity

Burning of fossil fuels and its Effects

Deforestation through slash and burn

Burning activity

Contributes 25% carbon dioxide

75% CO2 comes from burning of fossil fuel

Effect : The carbon dioxide level increases

1. Greenhouse effect2. Global warming

Atmosphere

Intensive Farming and its Effect Continuous cultivation of the same

plot of land.

The ploughing of land down the slope

instead of along the slope contours.

Overgrazing by livestock that does

not permit the grass to grow back.

The loss of topsoil nutrients.

The silting of the bottom of rivers

and lakes with earth sediment

causing flash floods.

Erosions of topsoil by

flowing water when it rains.

Intensive Farming and its Effect

Inorganic fertilizers - nitrates- phosphates- potassium

Eutrophication Lakes and river

Farmer

Cause

Used

Highly soluble and quickly leached out

Dumping of domestic and industrial waste and its Effects

Human population increased rapidly

Increase in 1. domestic waste2. industrial waste

Pollute:-ground- water resources

1. Dumping of waste

2. Discharge of effluents

Caused

Pollution

The impact of human activities on the

ecosystem

Greenhouse effect

Thinning of ozone layer

Pollution can be defined as any

undesirable changes in

physical, chemical and

biological characteristics of

the natural environment,

brought about when harmful

substances or energy are

released by human activities.

WHAT IS POLLUTION ?

Type of pollution

Water

Thermal

Noise

Sources:

- vehicles

- construction sites

- agricultural

- industrial machinery

Sources :

- in many industrial process

- in cooling towers of electrical power station

Sources:

- waste matter from industrial and domestic

- run-off fertilizer from agricultural area

Sources:

- mostly contributed from burning fossil fuels

- industrial plants and factories

Air

Air pollution

Factories that pump large amounts of carbon monoxide, oxides of

nitrogen and sulphur dioxide into the atmosphere.

Exhaust fumes from vehicles that contains soot, lead, carbon

monoxide, oxides of nitrogen and hydrocarbon.

Electrical power stations that release large amounts of carbon

dioxide into the atmosphere.

Open burnings that release suspended solids and pollutant gases

such as carbon dioxide and carbon monoxide.

Industrial Plants and Factories:

Large amount of

carbon monoxide,

oxides of nitrogen

and sulphur dioxide.

Open Burnings:

Large amount of

suspended solids.

Large amount of

carbon dioxide and

carbon monoxide.

Burning Fossil Fuels:

High level of carbon

particles.

High level of carbon

monoxide, oxides of

nitrogen and sulphur

dioxide.

POLLUTANTS IN THE AIR DUE TO

DIFFERENT SOURCES

Note:

Please refer to the acid rain handout

Water pollution

Human activities

on land are the main

contribution to water

pollution.

Crude oil spills that cover the water surface reduce water dissolved oxygen and water light intensity.

Industrial and domestic activities discharging untreated waste materials that dissolve or suspend in water and deteriorate the water quality.

The run-offs of fertilizers, pesticides and herbicides from agricultural activities into lakes and rivers affect the freshwater ecosystems.

Activity

The Effects of Water Pollution

Eutrophication

Increase BOD

Toxic Materials

Eutrophication

The Effects of Water Pollution

Eutrophication

Increase BOD

Toxic Materials

EUTROPHICATION

Leaching of inorganic fertilisers (nitrates and phosphates) from

agricultural lands

Input of untreated sewage

Run-offs containing animal wastes from pastures and farmlands anto

lakes, rivers or pond

Caused By

Excess of the organic and inorganic wastes that enter a river or a lake enrich the water

with nutrients

Photosynthesizing organisms particularly algae that grow rapidly, result in population

explosion known as algal bloom

High diversity of algae reduces the light intensity hence lead to the death of other

photosynthetic organisms

The decomposition of these dead organisms by aerobic bacteria causes severe depletion

of water dissolved oxygen,

Eutrophication

The aerobic bacteria use-up oxygen faster then it replenished; BOD increase

Causing the death of other aerobic organisms such as fish, prawns etc.

EUTROPHICATION

The artificial nutrient enrichment of an aquatic system with organic material or inorganic nutrients, causing an excessive growth of aquatic plant life

Increase BOD

The presence of organic materials in water

promotes the rapid growth of micro-organisms, thus

increase use-up of oxygen, leads to the increase of BOD (Biological Oxygen

Demand)

As a result, the dissolved oxygen in water is reduced and the life of the living

aquatic organisms is affected

What is Toxic Materials?

The illegal dumping of waste and effluent from heavy industries are the main source of toxic pollution, such as heavy metals and radioactive materials that are highly toxic, last for a long time and accumulate in living organisms via food chain

Thermal pollution

Thermal pollution occurs when excess heat which is released into the environment

harms the living organisms and the environment itself

Effluents of

industrial processes

Electrical power station cooling agent

Reflection of sunlight by mirror

Sources

The death of aquatic organisms that

only survive within a certain

range of temperature.

effect food chain

Increase in BOD value when the metabolic

rate of aquatic organisms increases

Disturbance of ecosystem balance when migrations of organisms occur.

The effects of the increase in water temperature

Noise Pollution

Motor vehicle

AeroplanesConstruction side

Agriculture and industrial machinery

Source

Effects of Noise Pollution

Safe noise level is ≤ 50 decibels

(dB) but above 80 dB can cause

deafness

Development and aggravation of stress

related problems such as high blood pressure,

coronary disease, ulcers, depression and

headaches

The Greenhouse Effect

What is greenhouse

effect?

Phenomenon to increase

the Earth temperature.

Without it the Earth would

be too cold for the survival

of living organisms

The Greenhouse Effect

• Greenhouse gases are carbon dioxide, CFCs, methane, nitrous oxide that contribute by the combustion of fossil fuels (coal, petroleum and natural gas) and other human activities such as increased deforestation and industrial production

• As the concentration of greenhouse gases rises, the more heat is trapped in the atmosphere and the Earth temperature is increased. This is known as global warming; overall rise in the average temperature of the atmosphere (cause changes in the global climate)

Carbon Dioxide andGlobal Warming

The effects of global warming

• As the temperature rises, the polar ice caps and glaciers melt

• This causes a rise in sea levels• Causes low-lying areas to be flooded

• Global warming leads to changes in wind direction and the distribution of rainfall; agricultural activities are affected

• Global warming causes weather patterns to change; affects the distribution of species

• Global warming increases the frequency of drought

• The land becomes dry and infertile• Lead to a drop in crop yields

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

• Lead to an expansion of territories for vectors, resulting in an increase in the outbreaks of diseases

Occurrence of floods Climate changes

Spread of diseasesOccurrence of drought

Solutions to Global Warming

• Reduce the burning of fossil fuels to conserve energy

• Develops alternative sources of energy such as wind, solar and geothermal energy

• Reduce deforestation for farming• Replant trees which have been cut down

The Thinning of the Ozone Layer• The ozone layer is a region in the stratosphere between

17 and 25 kilometres above the Earth surface• Ozone layer contains high concentrations of ozone

molecules (O3) that absorb UV radiation and shield organisms from its damaging effect

• The destruction of ozone layer is due to the increasing levels of chlorofluorocarbons (CFCs) in the atmosphere

• CFCs are used as coolants in air conditioners and refrigerators, as propellants in aerosol cans and as foaming agents in the making of Styrofoam packaging

• CFCs are a group of chemical compounds that contain chlorine, fluorine and carbon

Ozone Depletion

Ozone Depletion

protects fromUV rays

Ozone Depletion

Impact of ozone depletion on human and the ecosystems

Increase greenhouse effect

Skin Cancer

Cataract

Damaging the photosynthetic mesophyll

layers of plants

Reduce human immune system

Reduce nutrient contents and crop yields of plant

Kill microorganism and phytoplankton that are at the bottom of marine food chain

Ways to Reduce Ozone Depletion

• Reduce stop the use of CFCs• Replace CFCs with

hydrochlorofluorocarbon (HCFCs) and hydrofluorocarbon. These gases breakdown in the atmosphere and return to earth in form of rainwater