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Nutrient Cycles In this presentation you will: Identify the stages of the carbon and nitrogen cycles Investigate the causes of rising carbon dioxide levels.

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Presentation on theme: "Nutrient Cycles In this presentation you will: Identify the stages of the carbon and nitrogen cycles Investigate the causes of rising carbon dioxide levels."— Presentation transcript:

1 Nutrient Cycles In this presentation you will: Identify the stages of the carbon and nitrogen cycles Investigate the causes of rising carbon dioxide levels Explore the impact of the over-use of nitrogen based fertilizers ClassAct SRS enabled.

2 Nutrient Cycles Nutrient cycles summarize the movement of certain elements through ecosystems. In this presentation you will study the carbon and nitrogen cycles. You will identify the different stages of these cycles and investigate their importance. You will also investigate how human activity can disturb the natural balance of these cycles and cause pollution. Next >

3 Nutrient Cycles Nutrient cycles summarize the movement of certain elements through ecosystems. Elements may be combined to form complex organic molecules. These later decompose to form simpler organic and inorganic molecules. Nutrient Cycles These simpler molecules can be used again to become incorporated into living things. This is called the cycling pool. Next >

4 Nutrient Cycles Upsetting the Balance As well as the cycling pool of an element, all cycles have a larger reservoir pool. This is usually abiotic, that is, not made up of living things. Exchanges between the reservoir and the biotic cycling pools usually happen slowly. Human activity often speeds up the movement of molecules through the cycles. This may upset the natural balance, cause build up of substances at one point and cause pollution. Next >

5 Nutrient Cycles 1 Which part of a nutrient cycle involves living organisms? Question A) The cycling pool B) The reservoir pool C) Both the cycling and the reservoir pool D) Neither the cycling nor the reservoir pool

6 Nutrient Cycles The Carbon Cycle – An Overview CO 2 in atmosphere Photosynthesis Respiration Death C in detritus Detrivores, Decomposers C in humus Animals Combustion CO 2 in water (HCO 3 - ions ) C in algae Death Respiration by detrivores and decomposers Respiration Animals Death, Excretion Diffusion C in detritusFossil fuels eg coal, oil Flow of carbon in thousands of Tg/year Tg = Terragram 1 Tg = 1 million metric tons 1 metric ton = 1000kg Rocks in the Earth C = CarbonHCO 3 - = Hydrogen Carbonate Next >

7 Nutrient Cycles There are 4 large reservoirs of carbon: the atmosphere, the oceans, limestone rocksand fossil fuels. Photosynthesis Respiration Death C in detritus Detrivores, Decomposers C in humus Animals Combustion CO 2 in water (HCO 3 - ions ) C in algae Death Respiration by detrivores and decomposers Respiration Animals Death, Excretion Diffusion C in detritusFossil fuels eg coal, oil Flow of carbon in thousands of Tg/year Tg = Terragram 1 Tg = 1 million metric tons 1 metric ton = 1000kg Rocks in the Earth CO 2 in atmosphere CO 2 in water (HCO 3 - ions ) Rocks in the Earth Fossil fuels eg coal, oil Next >

8 Nutrient Cycles Next > The processes that put carbon dioxide into the atmosphere are: respiration, combustionand diffusion. CO 2 in atmosphere Photosynthesis Respiration Death C in detritus Detrivores, Decomposers C in humus Animals Combustion CO 2 in water (HCO 3 - ions ) C in algae Death Respiration by detrivores and decomposers Respiration Animals Death, Excretion Diffusion C in detritusFossil fuels eg coal, oil Flow of carbon in thousands of Tg/year Tg = Terragram 1 Tg = 1 million metric tons 1 metric ton = 1000kg Rocks in the Earth Respiration Combustion Diffusion Respiration

9 Nutrient Cycles Next > The processes that remove carbon dioxide from the atmosphere are: photosynthesis and diffusion. CO 2 in atmosphere Photosynthesis Respiration Death C in detritus Detrivores, Decomposers C in humus Animals Combustion CO 2 in water (HCO 3 - ions ) C in algae Death Respiration by detrivores and decomposers Respiration Animals Death, Excretion Diffusion C in detritusFossil fuels eg coal, oil Flow of carbon in thousands of Tg/year TG = Terra Ton 1 Tg = 1 million metric tons 1 metric ton = 1000kg Rocks in the Earth Photosynthesis Diffusion

10 Nutrient Cycles 2 Which of the following processes does not put carbon dioxide back into the atmosphere? Question A) Photosynthesis B) Combustion C) Respiration D) Decomposition

11 Nutrient Cycles There is a balance between the carbon (in carbon dioxide) stored in the atmosphere and the amount of carbon (in hydrogen carbonate ions) stored in the sea. Next > There is also a fine balance between the amount of carbon dioxide removed from the air by photosynthesis and the amount replaced by respiration. The Carbon Dioxide Balance

12 Nutrient Cycles Next > Despite the fact that these processes maintain a natural balance, the level of carbon dioxide in the atmosphere is still rising. This is because the burning of fossil fuels and wood releases carbon dioxide into the atmosphere. Upsetting the CO 2 Balance In addition to this, deforestation removes large areas of trees that would have absorbed large quantities of carbon dioxide for photosynthesis.

13 Nutrient Cycles 3 Why does deforestation result in increased carbon dioxide levels in the atmosphere? Question A) It results in fewer trees taking up nutrients from the soil B) It results in fewer trees being burnt C) It results in fewer trees respiring D) It results in fewer trees photosynthesizing

14 Nutrient Cycles Next > Around 1850, the atmosphere contained about 270ppm (parts per million) of carbon dioxide. In 2004, it contained around 360 ppm, and is rising at a rate of 1 to 2 ppm per year. The worst possible long term effect of increasing carbon dioxide levels in the atmosphere is the 'greenhouse effect', which in turn leads to global warming. The Greenhouse Effect and Global Warming Time (Years) Atmospheric CO2 levels (ppm)

15 Nutrient Cycles Next > The atmosphere is made up of 79% nitrogen. A shortage of nitrogen based compounds in ecosystems can reduce plant growth, and animal growth. The Nitrogen Cycle – An Overview

16 Nutrient Cycles The abiotic outer cycle consists of nitrogen from the air being 'fixed' by: NO 3 - NH 4 + NO 2 - Leaching to ground water Bacteria Nitrification = oxidation of ammonium to nitrate toxic Nitrogen fixation by lightning Nitrogen in plants e.g. protein Uptake of nitrates and ammonium Nitrogen in animals e.g. Protein Feeding Nitrogen in detritus and humus e.g. as protein Microorganisms: Bacteria and fungi Invertebrates Nitrogen gases in atmosphere Death and excretion Fertilizer manufacture (Nitrogen fixation by Haber-Bosch process) NO 3 -, NH 4 + Denitrification: denitrifying bacteria Free-living bacteria Bacteria in legume root nodules Nitrogen Fixation lightning Nitrogen fixation by lightning and the Haber-Bosch process. Fertilizer manufacture (Nitrogen fixation by Haber-Bosch process) Next >

17 Nutrient Cycles Nitrogen can also be fixed by bacteria in the root nodules of legumes and by bacteria living freely in the soil. NO 3 - NH 4 + NO 2 - Leaching to ground water Bacteria Nitrification = oxidation of ammonium to nitrate toxic Nitrogen fixation by lightning Nitrogen in plants e.g. protein Uptake of nitrates and ammonium Nitrogen in animals e.g. Protein Feeding Nitrogen in detritus and humus e.g. as protein Microorganisms: Bacteria and fungi Invertebrates Nitrogen gases in atmosphere Death and excretion Fertilizer manufacture (Nitrogen fixation by Haber-Bosch process) Denitrification: denitrifying bacteria Free-living bacteria Bacteria in legume root nodules Nitrogen Fixation NO 3 -, NH 4 + Next >

18 Nutrient Cycles Leguminous Plants Leguminous plants are plants that produce peas or beans. They contain nodules on their roots that are full of nitrogen fixing bacteria. Farmers often rotate crop plants with leguminous (pea or bean) plants. This is because crop plants take nitrogen from the soil and leguminous plants put nitrogen back into the soil. Root nodule Next >

19 Nutrient Cycles Rhizobium One of the most common bacteria that produce nodules on legumes is Rhizobium. The relationship between the bacterium and the plant is mutualistic, that is, both organisms benefit. The plant obtains some nitrogen from the bacterium and the bacterium obtains other nutrients, in particular, sugars, made by the plant. Rhizobium bacterium Next >

20 Nutrient Cycles In the central cycle, plants absorb nitrates or ammonium ions from the soil. NO 3 - NH 4 + NO 2 - Leaching to ground water Bacteria Nitrification = oxidation of ammonium to nitrate toxic Nitrogen fixation by lightning Nitrogen in plants e.g. protein Uptake of nitrates and ammonium Nitrogen in animals e.g. Protein Feeding Nitrogen in detritus and humus e.g. as protein Microorganisms: Bacteria and fungi Invertebrates Nitrogen gases in atmosphere Death and excretion Fertilizer manufacture (Nitrogen fixation by Haber-Bosch process) NO 3 -, NH 4 + Denitrification: denitrifying bacteria Free-living bacteria Bacteria in legume root nodules Nitrogen Fixation Nitrogen in plants e.g. protein The nitrogen forms amino acids and proteins. Uptake of nitrates and ammonium Next >

21 Nutrient Cycles These compounds may or may not be eaten by animals. NO 3 - NH 4 + Leaching to ground water Bacteria Nitrification = oxidation of ammonium to nitrate toxic Nitrogen fixation by lightning Nitrogen in plants e.g. protein Uptake of nitrates and ammonium Nitrogen in animals e.g. Protein Feeding Nitrogen in detritus and humus e.g. as protein Microorganisms: Bacteria and fungi Invertebrates Nitrogen gases in atmosphere Death and excretion Fertilizer manufacture (Nitrogen fixation by Haber-Bosch process) Denitrification: denitrifying bacteria Free-living bacteria Bacteria in legume root nodules Nitrogen Fixation Nitrogen in animals e.g. Protein However, they are all eventually turned into detritus (rotting organic matter). Death and excretion Nitrogen in detritus and humus e.g. as protein NO 3 -, NH 4 + NO 2 - Next >

22 Nutrient Cycles Detritus is attacked by detrivores and decomposers. NO 3 - NH 4 + NO 2 - Leaching to ground water Bacteria Nitrification = oxidation of ammonium to nitrate toxic Nitrogen fixation by lightning Nitrogen in plants e.g. protein Uptake of nitrates and ammonium Nitrogen in animals e.g. Protein Feeding Nitrogen in detritus and humus e.g. as protein Microorganisms: Bacteria and fungi Invertebrates Nitrogen gases in atmosphere Death and excretion Fertilizer manufacture (Nitrogen fixation by Haber-Bosch process) Denitrification: denitrifying bacteria Free-living bacteria Bacteria in legume root nodules Nitrogen Fixation NH 4 + Invertebrates Microorganisms: Bacteria and fungi NO 3 - The nitrogen is released as ammonium ions that are converted to nitrates. NO 3 -, NH 4 + NO 2 - Next >

23 Nutrient Cycles Next > The conversion of ammonium ions to nitrites and then to nitrates is known as nitrification. The bacteria that carry out nitrification are called nitrifying bacteria. They are chemoautotrophic, that is, they obtain their energy from oxidation of inorganic ions. Nitrification Nitrification = oxidation of ammonium to nitrate NO 3 -NH 4 + Bacteria NO 2 - toxic

24 Nutrient Cycles 4 Nitrogen fixing bacteria put nitrogen back into the soil. Answer True or False. Question

25 Nutrient Cycles 5 Nitrification is: Question A) The conversion of ammonium to nitrite B) The conversion of nitrate to nitrite C) The conversion of ammonium to nitrate D) The conversion of nitrite to nitrate

26 Nutrient Cycles Most nitrogen-based fertilizers are made by the Haber-Bosch process. This accounts for about one third of the total nitrogen fixation each year. Normally, natural nitrogen fixation would be balanced by denitrification. This is the process whereby bacteria take up inorganic nitrogen compounds and release nitrogen gas into the atmosphere. However, because there is more nitrogen being put into the soil than put back into the atmosphere, by the use of fertilizers, the balance is being disrupted. Upsetting the Nitrogen Balance Next >

27 Nutrient Cycles 6 Which of the following does not put nitrogen back into the ground? Question A) Lightning B) Denitrification C) Nitrification D) The Haber-Bosch process

28 Nutrient Cycles 7 Which of the following is the most harmful way of putting nitrogen back into ecosystems? Question A) Lightning B) The Haber-Bosch process C) Nitrogen fixing bacteria D) Death and excretion

29 Nutrient Cycles Nitrogen-based fertilizers lead to a type of pollution called eutrophication. The nitrates are washed by rainfall into ground water streams. Water supplies become enriched with nitrates. As a result of eutrophication, the algae at the water's edge grow rapidly. They prevent light from reaching aquatic plants. Eutrophication These plants, and the invertebrates that feed on them, then die. The algae also block water supplies, including drinking water. Next >

30 Nutrient Cycles Next > When the algae die, plants and invertebrates die and they are decomposed by bacteria. These bacteria deoxygenate, that is, remove oxygen from, the water. This is known as hypoxia. Hypoxia The bacteria also produce hydrogen sulphide gas, which is toxic. The fish and invertebrates that require high levels of oxygen die. This affects food webs and subsequently the entire ecosystem.

31 Nutrient Cycles 8 Which of the following is likely to be the best long-term solution for the problem of eutrophication? Question A) Re-stocking water systems with fish and invertebrates B) Removing pond weed and algae from water systems C) Supplying people with free bottled water D) Reducing the use of artificial fertilizers

32 Nutrient Cycles Summary Identify the stages of the nitrogen cycle After completing this presentation you should be able to: Identify the stages of the carbon cycle Show knowledge of the causes of increasing carbon dioxide levels Show knowledge and understanding of the consequences of the over-use of nitrogen based fertilizers End >


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