Form 4 Chapter 9: Endangered Ecosystem

Transcription

1 Form 4 Chapter 9: Endangered Ecosystem 1. Pollution: Any undesirable change in the physical, chemical or biological characteristics of the natural environment, brought about by human activities. 2. When the river is polluted: (a) High biochemical oxygen demand (BOD) (b) Low concentration of dissolved oxygen in the water (c) Present large number of microorganisms in the water and not living organisms (d) High amount of oxygen is taken up by microorganisms that decompose organic matter in water 3. Thermal pollution: (a) Discharge of hot water into the water sources (b) Reflection of heat from glass buildings (c) Power stations and factories 4. Effects of thermal pollution: (a) Rapid growth of algae (b) An increase in BOD value (c) Adversely influences the food chain and ecosystem (d) An increase in temperatures of water and the surrounding (e) Death of aquatic organisms as they cannot accommodate with the sudden change of water temperature 5. Types of Pollution Effect (A) Water Pollution (i) Oil spills - Destroy aquatic animal in the river. - Reduce oxygen content in the sea. (ii) Agricultural runoffs (including herbicides and pesticides) - Have toxic effects on a living organism when the water is drunk. - Eutrophication Result of an abundant supply of fertilizers or sewage in lakes, ponds or rivers. Fertilisers contain high content of nitrates and phosphates. When used excessively, these inorganic nutrients which are highly Solving Method - Use biogas technology like palm oil wastes are decomposed by microorganisms. The methane gas produced is used as fuel. - Agricultural industrial wastes are directly burned in a heating furnace and thick smoke is filtered. - The heat produced can generate electrical energy. 1

2 (iii) (iv) Untreated sewage (including effluents such as human wastes and domestic wastes) Nonbiodegradabl e rubbish soluble will not stay long in the soil and will go into rivers. Prevent sunlight from reaching plants in lower depths of water & plants die. Number of aerobic bacteria increases usage of O2 in water & concentration of O2 reduced. Rapid growth of algae and decomposition process by bacteria used up O2 supply in water & increase the BOD. BOD is the amount of O2 taken up by microorganisms that decompose organic waste matter in water. High BOD: Presence of large number of microorganisms which suggests a high level of pollution, lower concentration of dissolved O2 in water. Eutrophication process: Organic fertilizer flows into the lake Block out light for plant Rate of photosynthesis Dissolve oxygen Algae grow and cover the surface of the lake The rate of bacteria reproduction increases Used up oxygen BOD value increases Aquatic organism die lack of oxygen - Pathogen such as vibrio bacteria is found in unpurified water which can cause cholera. - Floating rubbish & oil reduce the penetration of light & diffusion of oxygen into water, leading to death of aquatic organisms. - Organic fertilizers does not contain many nitrates & release nutrients gradually giving crops time to absorb. - Recycling the waste. - Love Our River campaign. - When sewage is treated, water can be used again. - Disposal drums made of strontium to keep radioactive wastes like uranium / plutonium deep 2

3 (v) (B) (i) (ii) (iii) (iv) Industrial wastes (toxic chemical wastes from electronic factories, organic wastes from remains of oil palms and rubber plantations) Air Pollution Fossil fuels burning (petroleum, natural gas and coal) Release of carbon monoxide Release acidic gases (by vehicle) Release of smoke, dust or soot (by factory) - Contaminate water physically. - Decomposition of organic wastes reduces concentration of O2 in water. - Accumulation of toxic chemicals (non-biodegradable) through food chain in aquatic organisms results in poisoning of aquatic animals and man. - Toxic substances damage body organs and harmful to man, causing cancer & mutation. - Release of CO2 which absorb & trap heat from sun, cause greenhouse effect. The effect: Weather warmer. Desert area bigger. Sea level rise / flash flood. Global warming. - When burning during lack of oxygen, the effect is reducing the ability of red blood cells to carry oxygen to the brain. - Sulphur dioxide & nitrogen dioxide cause acid rain which corrodes roof & destroy aquatic life. - Cause haze. - Visibility reduced. - Respiratory problem. - Reduce the rate of photosynthesis. - Decreases light intensity. - Destroy plants / trees. below the soil surface ocean. - Enforcement of laws. - Education / awareness campaigns. - Enforcement of the Natural Forestry Act to encourage replanting of trees. - Use scrubber (liquid spray) to dissolve poisonous gases such as nitrogen dioxide / sulphur dioxide. - Use electrostatic precipitator in chimney. - Fix electrostatic precipitator / air filter to filter smoke in the chimney. - The filtered coal ashes can be used to process fertilizer. 3

4 (v) (vi) (vii) (viii) (C) (i) (ii) (iii) (iv) (D) (i) Burning down the forest Radioactive radiations (nuclear power stations) Agrochemica l substances (activities of agricultural industry) Chlorofluoro carbon - Lungs cancer. - Asthmatic. - Causes mutation, cancer and genetic diseases. - Can passed on in food chains and become concentrated in body, causing harm to organisms because it is nonbiodegradable - Hinder the physiological process. - Toxic to body. - Chlorine causes ozone depletion and global warming. - Skin cancer, sunburn, UV radiation. - Crop yield reduced due to UV radiaton. - Rate of photosynthesis increases. - Distrupt food chain & damage egg of certain amphibian. Noise Pollution Automobiles - World Heath Organization (WHO) and airplanes recommends a noise level of not Construction more than 55 decibels. sites - Prolonged exposure to the Entertainment surrounding noise level of more sites than 80 decibels will cause severe Operating headaches, emotional and machines deafness, heart attack. Land Pollution Disposal of domestic waste on the ground - Increase number of pest / rat / cockroach / flies. - Increase disease transmission. - Conservations efforts need to be done on forests because multitude of trees can generate more oxygen & reduce amount of carbon dioxide in atmosphere. - Education / awareness campaigns. 4

5 Experiment: Aim: To analyse data on water pollution. Variables Manipulated: Samples of water Responding: Time taken for methylene blue solution to decolourise Constant: Volume of the methylene blue solution A reagent bottle containing one of the water samples Discussion: 1. Rapid decolonisation of the methylene blue solution shows that the water has very little oxygen. Hence, the B.O.D. value of the water sample is high. 2. A high B.O.D. value means that the content of oxygen is very low because of the large number of organic substances and bacteria in it. Hence, the water is most polluted. 3. Slow decolourisation of the methylene blue shows that the B.O.D. value is low and the water is the least Problem Statement: What inference can be made on the level of water pollution for different sources of water based on the B.O.D. value? Apparatus: Four samples of water from different sources, reagent bottle with stoppers, stopwatch Materials: Syringe, 0.1% methylene blue solution Hypothesis: The higher the B.O.D. value, the more polluted the source of water. Technique: Record the time taken for methylene blue solution to decolourise by using a stopwatch. Procedure: ml of river water is collected in a reagent bottle. 2. By using a syringe, 1 ml of 0.1% methylene blue solution is added to the bottom of the water sample as shown in Figure. 3. The reagent bottle is closed with its glass cover and labelled P. Do not shake the mixture of water and methylene blue. 4. Steps 1 to 3 are repeated using water from different sources such as drain water, pond water, well water and tap water. The bottles are labelled Q, R, S, T respectively. 5. All the bottles are kept in a dark cupboard and the time is recorded. 6. At intervals of one hour for a period of four hours, each bottle is examined for any change of the colour of the methylene blue to become colourless. The time taken for the methylene blue solution to be decolourised is recorded. Results: Water sample River water (P) Drain water (Q) Pond water (R) Well water (S) Tap water (T) Time taken for discolourisation of methylene blue solution 1 hour 2 hours 3 hours 4 hours Blue Colourless Colourless Colourless Blue Blue Colourless Colourless Blue Blue Blue Colourless Blue Blue Blue Blue Blue Blue Blue Blue polluted. Conclusion: 1. The hypothesis is accepted. 2. The river water has the highest B.O.D. value. Hence, the river water is most 5

6 polluted. 3. The tap water has the lowest B.O.D. value. Hence, the tap water is the least polluted. 6. Acid rain: Increases the acidity of aquatic ecosystems leading to the killing of planktons and aquatic organisms Destroys plant tissues and damages plant roots Corrodes metals, marble, rubber, plastics, stonework and other materials EFFECT OF ACID RAIN Leaching of minerals from the soil such as calcium, causing infertile soil Reduces the ph of the soil making it unsuitable for farming Releases ions of heavy metals such as lead which may contaminate the water 7. The greenhouse effect: (i) The phenomenon of over warming of earth due to increasing amount of greenhouse gases such as CO 2 gas that causes greenhouse effect, methane (CH 4 ), nitrous oxide (N 3 O) and chlorofluorocarbons (CFCs) that are released will form a layer of gas in the atmosphere. (ii) Energy from the Sun reaches Earth through radiation to warm surfaces of sea and land. (iii) As the Earth is warmed, heat in form of infrared radiation is prevented from radiated back into space. (iv) As a result, the infrared radiation is radiated back to the Earth's surface and warmed the Earth further. (v) An increase in greenhouse gases is caused by human activities, mainly burning of fossil fuels and deforestation. Effect of greenhouse effect: (i) The increase in carbon dioxide concentration traps heat. (ii) Cause a rise in the Earth s temperature. (iii) The melting of polar ice raises the sea level. 8. Measures needed to overcome the phenomenon: (a) Stop the practice of open burning of rubbish. (b) Conservations efforts need to be done on forests and reduce the amount of carbon dioxide in the atmosphere through the photosynthesis process. (c) Enforcement of the Natural Forestry Act to minimise deforestation and encourage replanting of trees. 6

7 (d) Recycling paper can reduce cutting down of trees. (e) Impose maximum fine to factories and vehicles that release excessive levels of smoke to atmosphere. (f) Use public transport. (g) Use alternative energy from natural source. 9. Effect of phenomenon if the concentration levels of carbon dioxide are increasing: (a) Solar radiation enters the Earth by penetrating the atmosphere. The solar radiation will be changed into heat energy. (b) Part of the heat energy will be radiated back into space in infracted radiation form whereas rest remain in atmosphere is absorbed by carbon dioxide. (c) If the carbon dioxide concentration level increases, more heat will be trapped and it will not be able to escape from the atmosphere. (d) The consequence is an increase in Earth s temperature. (e) Also causes global warming and melting of ice at the poles. (f) The sea level rises which causes low-lying areas to be flooded. (g) Affect the weather pattern, wind direction and rainfall. (h) Affect the yield of crops and water supply. (i) Land becomes dry and infertile due to drought. 10. Global warming: Excessive deforestation increases the concentration of CO 2 that can trap heat in the atmosphere, causing a rise in the temperature. Example: Forest burning. The Effects of Global Warming Spread of pests of diseases-carrying Infertility of soil and a decline in the yield vectors. of crops. Melting of polar ice at the poles and Changes in weather pattens with intense increase in sea levels. rains in some countries. Floods in low-lying countries and Changes in sea current and wind droughts. direction which cause climate change. Extinction will cause great biodiversity Disruption to the carbon cycle and loss. nitrogen cycle. Steps to Reduce Damage to the Environment By replanting plant, sharing transport and reducing the usage of fossil fuel, we can greatly reduce the concentration of CO2 in atmosphere to reduce the problem of global warming. 11. Deforestation: Good Effects Bad Effects (a) Improves (a) Causes loss of habitat for wildlife. infrastucture (b) Exposure of the soil layer to wind & air may cause thinning of residential of soil. As the top layer of soil crumbles, this may lead to area such as landslide. Soil erosion (heavy rain water flow soil down the new river & water level rise causing flood to occur). development (c) Reduction in the number of trees may contribute to global buildings & warming. roads. (d) Damage water catchment area that leads to flash flood. 7

8 (b) Increases job opportunities of that area. (e) Increase in CO 2 amount in air. (f) Causes loss of biodiversity (destruction of natural habitat). (g) Leads to extinction of many species. (h) Destruction of recreational sites. (i) Melting of ice at Artic / Antartic, drought occur. (j) Reduce water catchment area. (k) Flash floods. Thinning of the Ozone Layer (a) Ozone layer is present in the atmosphere. (b) High concentrations of ozone layer can absorb large quantities of UV radiation from the sun. (c) This ozone layer shields the Earth from the harmful effects of UV radiation. (d) Chlorofluorocarbon (CFC) is the causing factor. During the Destruction of the Ozone Layer (a) Ultra violet ray breaks down CFC molecules from the air conditioner and releases a chlorine atom. (b) The highly reactive chlorine atoms break down ozone layer & produce chlorine monoxide and oxygen molecules. (c) Free oxygen atom will break the chlorine monoxide bond. (d) Free chlorine atom repeats the chain reaction. Impact on the Environment (a) Allow the UV light to penetrate to the Earth. (b) Destroy plankton in the food web. (c) Disturb the ecology balance in the water ecosystem. (d) Decrease the number of stomata and chlorophyll on the leaves. (e) Plant cannot carry out photosynthesis / biotic component threatened. (f) Many plants die causing carbon dioxide to increase. (g) Atmospheric temperature increases. (h) Lead to green house effect / global warming. (i) Many organisms which feed on plants die. (j) Disturb the food web / ecosystem. Ways to Reduce the Impact on the Environment (a) Introduce new chemical substance HCFC to replace the used of CFC. (b) Enforce the laws to ban the use of material contains CFC. Recycling: Collecting and segregating waste according to type of material & turning waste into new products. (a) Glass and bottles can be reused. (b) Plastic can be processed into waste paper baskets. (c) Save energy & reduce use of natural source. (d) Maintain balance of nature by practising 4R. 8