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CHAPTER 9: ENDANGERED ECOSYSTEM 9.1 Human Activities that Endanger an 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 Leads to

Burning of fossil fuels Leads to

Overuse of fertilisers in intensive farming Leads to

• Soil erosion

• greenhouse effect

• eutrophication

• landslides

• global warming

• water pollution

• flash floods

• air pollution

• climatic changes • lost of biodiversity • greenhouse effect

Dumping of domestic and industrial waste Leads to • water pollution


Deforestation Important roles of tropical rainforests:

 The oldest ecosystem on the Earth

Deforestation

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.

The impacts are:

 Regulate the world climate.

 Soil erosion

 Act as a carbon sink of the Earth

 Flash flood

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

 As water catchments areas.

 Landslides  Changes in the recycling of materials

 Severe climatic changes  The loss of biodiversity


Deforestation


Deforestation

 Loss of habitat  Loss of biodiversity


Burning of fossil fuels and its Effects Deforestation through slash and burn

Burning activity

75% CO2 comes from burning of fossil fuel 1. Greenhouse effect 2. Global warming

Contributes 25% carbon dioxide

Atmosphere

Effect : The carbon dioxide level increases


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 Used Farmer

Inorganic fertilizers - nitrates - phosphates - potassium Highly soluble and quickly leached out

Eutrophication

Cause

Lakes and river


Dumping of domestic and industrial waste and its Effects Human population increased rapidly

Caused

Pollute: -ground - water resources

Increase in 1. domestic waste 2. industrial waste

1. Dumping of waste 2. Discharge of effluents


The impact of human activities on the ecosystem

Pollution

Thinning of ozone layer Greenhouse effect


WHAT IS POLLUTION ? 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.


Sources: - vehicles

Sources:

- construction sites

- mostly contributed from burning fossil fuels

- agricultural

Air

- industrial plants and factories

- industrial machinery

Noise

Sources : - in many industrial process - in cooling towers of electrical power station

Type of pollution

Wate r Sources:

Thermal

- waste matter from industrial and domestic - run-off fertilizer from agricultural area


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.


Burning Fossil Fuels:

 High level of carbon particles.

 High level of carbon

POLLUTANTS IN THE AIR DUE TO DIFFERENT SOURCES

monoxide, oxides of nitrogen and sulphur dioxide.

Industrial Plants and Factories:

Large amount of carbon monoxide,

Note:

oxides of nitrogen

Please refer to the acid rain handout

and sulphur dioxide.

Open Burnings:

Large amount of suspended solids.

Large amount of carbon dioxide and carbon monoxide.


Water pollution ďƒ˜ Crude oil spills that cover the water surface reduce water dissolved oxygen and water light intensity.

Human activities

Activity

ďƒ˜ Industrial and domestic

on land are the main contribution to water pollution.

ďƒ˜

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.


The Effects of Water Pollution Eutrophication

Increase BOD

Toxic Materials


Eutrophication


Eutr oph icat ion

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

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

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,


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

Sources

Reflection of sunlight by mirror


The effects of the increase in water temperature

The death of aquatic organisms that only survive within a certain range of temperature.

Increase in BOD value when the metabolic rate of aquatic organisms increases

Disturbance of ecosystem balance when migrations of organisms occur.


Noise Pollution Motor vehicle

Construction side

Source

Aeroplanes

Agriculture and industrial machinery


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 and Global Warming


The effects of global warming Occurrence of floods • 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

Climate changes • 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

Spread of diseases Occurrence of drought • 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


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 from UV rays


Ozone Depletion


Impact of ozone depletion on human and the ecosystems

Increase greenhouse effect

Cataract

Skin Cancer

Reduce nutrient contents and crop yields of plant

Reduce human immune system Damaging the photosynthetic mesophyll layers of plants

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


Ways to Reduce Ozone Depletion • Reduce or stop the use of CFCs • Replace chlorofluorocarbons with hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs). This gases break down in the atmosphere and return to earth in the form of rainwater


BIOLOGY ECOSYSTEM Chapter 9