Maktab Rendah Sains MARA Beseri, Perlis

Dynamic & Endangered Ecosystem

Biology Folio

Lukman Hakim A. Rahman4 Glorious | 2010

Acknowledgement

Alhamdulillah, with the strength, health and time given, I have successfully completed my assignment for Biology.

I would like the thank Puan ??? for giving this task to me and also giving me full guidance and support to help me complete this assignment. Without your help, I will surely fail to accomplish this task given.

Not forgotten to my family for plenty of help given since the start of this task. They had given support, courage and will to accomplish this task. Without their motivation, I would be lost in trying to complete this task.

Last but not least, to my friends who pushed me into completing this task and for being together in getting resources.

Thank you all for your kindness and gratitude.

Introduction

Human activities often affect the whole ecosystem. With great advancements in the medical field, modern farming techniques and better infrastructure, the world’s population has grown to over 6 billion today.

Conflicts, therefore, 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.

Many of the problems related to the environment are the result of human activities and human interference with the ecosystems.

The negative effects of hasty, unplanned development and the mismanagement of the ecosystems result in various environmental problems such as 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 ecosystems.

1 – The impact of human activities on the ecosystem.

1.1 – PollutionPollution 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.

There are four types of pollution : air, water, thermal and noise poluution.

1.1.1 – Air Pollution

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

When fossil fuels are burnt, the elements in the fossil fuels are oxidized, forming various air pollutants. These include carbon dioxide (CO2), sulphur dioxide (SO2), oxides of nitrogen (NO2 and NO) and fine particulate matter.

Pollutants Sources Effects Solutions

Carbon monoxide (CO)

Incomplete combustion of fossil fuels

The exhausts of vehicles

Factories

Health: Combines readily with haemoglobin and affects the

transport of oxygen to body cells Impairs alertness, causes fatigue and headaches

Sulphur dioxide (SO2)

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 asmathic attacksClimate: Combines with rainwater to form acid rainAgriculture: Contributes to acid rain which damages photosynthetic

tissues Acid rain lowers pH of soil, rivers and lakesBuilding: Acid rain corrodes iron, limestone and stonework, and

destroys buildings.

Use low sulphur content fuels

Clean up emissions from power stations and factories with scrubbers.

Oxides of nitrogen(NO and NO2)

Vehicle exhausts

Action of bacteria on fertilisers

Combustion of fossil fuels

Factories

Health: Irritate lungs, nose, throat and eyes Cause respiratory infections Cause bronchitisClimate: Dissolved in rainwater to form acid rainAgriculture: Contributes to acid rain which lowers pH of soil, making

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

it unsuitable for cultivation of crops Damages leaves and rootsBuildings: Acid rain corrodes metal and destroy stonework on

buildings

Lead (Pb)

Combustion of fossil fuels

Vehicle exhaust fumes

Health: Retards mental development and damages the liver Can result in coma or death

Use unleaded petrol.

Carbon dioxide (CO2)

Open burning Combustion of

fossil fuels

Health: Affects respirationClimate: Leads to greenhouse effect and global warming Results in an increase in the atmospheric temperature Climate changes

Reduce the use of fossil fuels.

Fine particulate matter

Incomplete combustion of fossil fuels

Exhaust fumes Quarries,

sawmills and asbestos factories

Health: Irritates the eyes, nose and lungs Damage the respiratory passages and lungs Haze can cause conjunctivitis, sore throats, influenza,

asthma, and lead to bronchitis Dust from quarries, sawmills, and asbestos factories can

cause lung diseases Haze leads to reduced visibility

More efficient burning of fuels in well-designed furnaces

Stop open burning

Acid Rain

Causes of acid raina. 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 (SO2) and oxides of nitrogen (NO and NO2).

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.

Effects of acid raina. Agriculture

The soil becomes very acidic and unsuitable for the cultivation of crops. Acid rain causes the leaching of minerals such as potassium, calcium and

magnesium. This affects the growth of crops. Photosynthetic tissues are destroyed. Plant leaves turn yellow and fall off. The

roots are damaged and cannot absorb minerals.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.

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

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

weathering. Acid rain can be reduced by

a. Cleaning up emissions from power stations and industrial plants with scrubbers. This process involves the spraying of water to trap pollutants.

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

Air pollutant index

1. The air quality is measured by the air pollutant index (API).2. This index is calculated based on the concentrations of several major air pollutants.3. Air pollution levels are divided into five bands as shown below:

4. When the API reading is between 201 – 300, there is a significant increase in respiratory problems, such as wheezing and a shortness of breath in people with asthma. The health of patients with heart and lung conditions worsens.

1.1.2 – Water pollution

1. Water sources are the most easily polluted as they are most affected by human activities.2. Industrial, domestic and agricultural activities produce waste which pollutes water.

Sources Components/pollutants and their effects SolutionsAgricultural runoffs and waste from oil palm and rubber processing mills

Nitrates and phosphates (in fertilisers) Excess nitrates and phosphates lead to eutrophication

Control the use of fertilisers bya. Applying only when crops are

growingb. Not applying in empty fieldsc. Not spraying when there is a

forecast of raind. Not disposing of them into rivers

and pondse. Reducing the usage of excess

nitrates from fertilisers and ammonia

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

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

The pesticide 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.

Use biodegradable pesticides Use biological pest control

methods Plant genetically modified crops

that resist pest attacks.

Untreated sewage

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.

Treat sewage before it enters rivers.

Prevent farm slurry from enetering rivers and ponds

Nitrates and phosphates Lead to eutrophication

Domestic waste Detergents ‘Hard’ detergents create foam which reduces the supply of

oxygen to organisms living in water. ‘Soft’ detergents can also lead to eutrophication.

Use biodegradable detergents with low phosphate content.

API Descriptor0 – 50 Good

51 – 100 Moderate101 – 200 Unhealthy201 – 300 Very unhealthy

>300 Hazardous

Animal waste Microorganisms such as bacteria and protozoa Can cause water-borne diseases such as cholera.

Drink properly treated and boiled water.

Effluents from industries

Heavy metals which is highly toxic. Oil, grease and suspended solids Waste water that contains numerous contaminants

Treat effluents before discharged

Take legal actionUnderground pipes

Lead Lead is a highly toxic heavy metal Can impair the mental ability

Use copper pipes instead of lead pipes in plumbing.

Eutrophication

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

Eutrophication can be caused by:a. The leaching of inorganic fertilisers, especially nitrates and phosphates, from agricultural lands.b. The input of untreated sewage as well as discharge from sewage treatment plantsc. Run-offs containing animal wastes from pastures and farmlands into lakes, rivers or ponds.

1.1.3 – Thermal pollution

Causes of thermal pollution

Hot water is discharged into nearby lakes and rivers from the effluents of industrial processes. The excess heat that is released into the environment leads to thermal pollution. Thermal pollution causes the temperature in a body of water to rise above the normal value.

The increase in temperature can be between 5o C and 10o C.

Effects of thermal pollution

Water temperature can affect the level of dissolved oxygen. When the temperature of water increases, oxygen becomes less soluble in water.

- For some species, a sudden increase in temperature can lead to instant death because many aquatic species can only survive within a certain range of temperature.- The death of these species may have a negative effect on the food chain, causing the entire ecosystem to collapse.

For other species, for example, algae, an increase in temperature actually encourages their rapid growth which, in turn, leads to a higher oxygen demand (BOD) value.

Ways to prevent thermal pollution

Control the amount of hot water discharged by industrial facilities. Control the amount of hot water or industrial effluents discharged into still or slow – moving rivers.

1.1.4 – Noise pollution

1. Noise from cars, motorcycles, aeroplanes, construction sites, agricultural and industrial machinery can be a form of pollution.

2. The noise level of residential areas should not exceed 55 decibels (dB).3. According to WHO, prolonged exposure to noise levels at or above 80 dB can lead to deafness.4. Excessive exposure to high levels of noise is considered a health risk because it can lead to stress-

related problems.5. Loud noise can cause an arousal response in which series of reactions occurs in the body. Adrenaline

is released into the bloodstream. A person’s heartbeat rate, blood pressure, and respiration rate are likely to increase. The blood vessels constrict and the muscles become tense.

6. It is possible that constant exposure to noise can be harmful to health.

1.2 – Deforestation and its effects

The rapid destruction of woodlands or the removal of trees from forests is known as deforestation. Every year, vast areas of forests are cleared to make way for agriculture and development. Tropical rainforests have important ecological roles:

Rainforests are the oldest ecosystem on Earth and house almost half of the flora and fauna of the world.

They contain many unique species which provide food, medicine and other biological products. Rainforests regulate climate by influencing wind, rainfall, humidity and temperature patterns. 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. They also serve as water catchment areas.

Despite their importance, it has been estimated that more than 50 million acres of rainforests are destroyed or seriously degraded every year. In general, deforestation results in:

Soil erosion Flash floods Landslides Disruption to the carbon and nitrogen cycles Severe climatic changes The loss of biodiversity

1.2.1 – Soil erosion, landslides and flash floods Without proper development and planning, a land stripped of its vegetation is subject to soil

erosion. Soil erosion is the removal and thinning of the soil layer due to physical and climatic processes, such as high rainfalls.

The absence of plant root systems makes the soil structure unstable. When there are many heavy rains for a long period of time, the top layer of the soil crumbles and

this leads to landslides on steep hillsides. The eroded soil is then carried by moving water and deposited at the bottom of rivers. This, together with the depletion of water catchment areas, causes flash floods furing the rainy

seasons.

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

The removal of the bases of numerous food webs. The loss of habitats of many species of flora and fauna. 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 source of food and priceless medicines to mankind.

1.2.3 – Climatic changes

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

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

This leads to an increase in the carbon dioxide level in the atmosphere. High level 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.

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

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

1.3 – The greenhouse effectThe greenhouse effect is an effect in the atmosphere as a result of the presence of certain gases, called the greenhouse gases.

Carbon dioxide, chlorofluorocarbons (CFC), methane, nitrous oxide, low level ozone, and water vapour make up the greenhouse gases.

With the exception of CFCs, most of the greenhouse gases occur normally. However, all of them are also the results of human activities.

Scientists believe that the combustion of fossil fuels and other human activities are the primary reasons for the increased concentration of atmospheric CO2.

As these gases increases, they trap more heat in the atmosphere and raising the average temperature on earth.

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