NITROGEN CYCLE. Big Question. Dr. B. K. Bindhani Assistant Professor KIIT School of Biotechnology KIIT University, Bhubaneswar, Orissa, Indi.

Transcription

1 ITROGE CYCLE Big Question Why Are Biogeochemical Cycles Essential to Long-Term Life on Earth? Dr. B. K. Bindhani Assistant Professor KIIT School of Biotechnology KIIT University, Bhubaneswar, Orissa, Indi.a

2 What is nitrogen?

3 ITRODUCTIO 1.itrogen is the most abundant element in our planet s atmosphere. Approximately 78% of the atmosphere is comprised of this important element. 2.itrogen is used by life forms to carry out many of the functions of life. 3.This element is especially important to plant life. 4.Yet nitrogen in its gaseous form is almost entirely unusable to life forms. 5. It must first be converted or fixed into a more usable form.

4 This cartoon shows some of the gases in Earth's troposphere. There is more nitrogen ( 2 ) than anything else. There is also a lot of oxygen (O 2 ). The cartoon also shows carbon dioxide (CO 2 ), water vapor (H 2 O), methane (CH 4 ), sulfur dioxide (SO 2 ), and carbon monoxide (CO).

5 6.The process of converting nitrogen is called fixation. 7.There are specialized bacteria whose function it is to fix nitrogen, converting it, so that it can be used by plants. 8.There are still other bacteria who do the reverse. That is, they return nitrogen to is gaseous form. 9. After nitrogen is fixed, it can be absorbed, and used by plants, and subsequently by animals.

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7 ITROGE CYCLE The process of nitrogen being fixed, used by plants and animals, and later returned to the atmosphere is referred to as the nitrogen cycle.

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9 Periodic Table itrogen is in the onmetals/bco Group

10 Where is nitrogen found in the environment?

11 The largest single source of nitrogen is in the atmosphere itrogen makes up 78% of our air!

12 What happens to atmospheric nitrogen ( 2 ) in the nitrogen cycle?

13 Atmospheric nitrogen is converted to ammonia or nitrates Atmospheric itrogen ( 2 ) Ammonia (H 3 ) itrogen combines with Hydrogen to make Ammonia itrates (O 3 ) itrogen combines with Oxygen to make itrates

14 Why does atmospheric nitrogen need to be converted?

15 It is one of nature s great ironies itrogen is an essential component of DA, RA, and proteins the building blocks of life. Although the majority of the air we breathe is nitrogen, most living organisms are unable to use nitrogen as it exists in the atmosphere!

16 How does atmospheric nitrogen get changed into a form that can be used by most living organisms?

17 BY TRAVELIG THROUGH OE OF THE FOUR PROCESSES I THE ITROGE CYCLE! (4) Denitrification (1) itrogen Fixation itrogen Cycle (3) itrification (2) Ammonification

18 The first process in the nitrogen cycle is itrogen Fixation! (1) itrogen Fixation itrogen Cycle

19 What is nitrogen fixation and what does it mean to say nitrogen gets fixed?

20 itrogen Fixation is the process that causes the strong twoatom nitrogen molecules found in the atmosphere to break apart so they can combine with other atoms. Oxygen Hydrogen Hydrogen Oxygen itrogen gets fixed when it is combined with oxygen or hydrogen.

21 There are three ways that nitrogen gets fixed! (a) Atmospheric Fixation (b) Industrial Fixation (c) Biological Fixation Bacteria

22 Atmospheric Fixation (Only 5 to 8% of the Fixation Process) The enormous energy of lightning breaks nitrogen molecules apart and enables the nitrogen atoms to combine with oxygen forming nitrogen oxides ( 2 O). itrogen oxides dissolve in rain, forming nitrates. itrates (O 3 ) are carried to the ground with the rain. Lightning fixes itrogen! ( 2 O) (O 3 ) O itrogen combines with Oxygen itrogen oxides forms itrogen oxides dissolve in rain and change to nitrates Plants use nitrates to grow!

23 Industrial Fixation Under great pressure, at a temperature of 600 degrees Celcius, and with the use of a catalyst, atmospheric nitrogen ( 2 ) and hydrogen are combined to form ammonia (H 3 ). Ammonia can be used as a fertilizer. (H 3 ) H 3 H Industrial Plant combines nitrogen and hydrogen Ammonia is formed Ammonia is used a fertilizer in soil

24 Biological Fixation (where MOST nitrogen fixing is completed) There are two types of itrogen Fixing Bacteria Free Living Bacteria ( fixes 30% of 2 ) Symbiotic Relationship Bacteria ( fixes 70% of 2 )

25 Free Living Bacteria Highly specialized bacteria live in the soil and have the ability to combine atmospheric nitrogen with hydrogen to make ammonia H (H 3 ). H 3 Free-living bacteria live in soil and combine atmospheric nitrogen with hydrogen (H 3 ) itrogen changes into ammonia Bacteria

26 Symbiotic Relationship Bacteria Bacteria live in the roots of legume family plants and provide the plants with ammonia (H 3 ) in exchange for the plant s carbon and a protected home. H 3 Legume plants Roots with nodules where bacteria live itrogen changes into ammonia.

27 Most atmospheric nitrogen ( 2 ) is fixed and changed to ammonia (H 3 ). Ammonia is highly toxic to many organisms. Can plants use ammonia?

28 Very few plants can use ammonia (H 3 ) (1) itrogen Fixation (2) Ammonification but, fortunately the second process Ammonification can help!

29 What is ammonification?

30 Ammonification: Bacteria decomposers break down amino acids from dead animals and wastes into nitrogen ammonium. Bacteria decomposers break down amino acids into ammonium

31 Why is ammonification necessary?

32 Because plants cannot use the organic forms of nitrogen that are in the soil as a result of: (1) wastes (manure and sewage). (2) compost and decomposing roots and leaves.

33 How does ammonification occur?

34 Microorganisms convert the organic nitrogen to ammonium. The ammonium is either taken up by the plants (only in a few types of plants) or is absorbed into the soil particles. Ammonium (H 4 ) in the soil is stored up to later be changed into inorganic nitrogen, the kind of nitrogen that most plants can use. Bacteria converts organic nitrogen to ammonium (H 4 ) Bacteria Ammonium (H 4 ) is used by some plants Ammonium (H 4 ) is stored in soil.

35 What happens to ammonium (H 4 ) stored in the soil?

36 It travels through the third process of the nitrogen cycle called itrification! (1) itrogen Fixation (3) itrification (2) Ammonification

37 First we will quickly run through a general overview of the itrification Process

38 itrifying bacteria in the ground first combine ammonia with oxygen to form nitrites. Then another group of nitrifying bacteria convert nitrites to nitrates which green plants can absorb and use! itrifying bacteria in soil combine ammonia with oxygen Ammonia changes to nitrites itrifying bacteria in soil convert nitrites to nitrates Ammonia itrites itrates Plants absorb nitrates and grow! (H 3 ) (O 2 ) (O 3 )

39 ow we will take a closer look at the itrification Process

40 itrification is a biological process during which nitrifying bacteria convert toxic ammonia to less harmful nitrate. itrification aids in the decomposition of nitrogenous material and thus in the recycling of nitrogen atoms since the decontamination of organic nitrogen produces ammonia that is subsequently oxidized to nitrate by nitrification. There two bacterial species involved. itrosomonas sp. Bacteria oxidize ammonia into nitrite, while itrobacter bacteria convert nitrite to nitrate, with both species utilizing the energy released by the reactions. Ammonia can be used by some plants. Most nitrogen taken up by plants is converted by chemoautotrophic bacteria from ammonia, which is highly toxic to many organisms, first into nitrite (O 2- ), and then into nitrate (O 3- ). This process is called nitrification, and these bacteria are known as nitrifying bacteria.

41 itrifiers such as Arthrobacter (heterotroph), Aspergilli s (heterotroph), and itrosomonas (autotroph) are delicate organisms and extremely susceptible to a variety of inhibitors. They are extremely slow growing, unlike many bacteria that can double their numbers every hour or so. In order to thrive, nitrifying bacteria need a relatively clean environment with a steady supply of ammonia and oxygen.

42 itrification is a Two Step Process 1. First Step: Ammonium Oxidation The microorganisms involved are called the ammonia oxidizers. itrosomonas is the most extensively studied and usually the most numerous in soil. itrosospira is an aquatic nitrifier. itrosomonas. itrosospira. itrosococcus. itrosolobus. Ammonia-Oxidizing Bacteria: These organisms are chemoautotrophs, growing with ammonia as the energy and CO 2 as the main carbon source. Species are distributed in a great variety of soils, oceans, brackish environments, rivers, lakes, and sewage disposal systems.

43 2. Second step: itrite Oxidation Microorganism involved: itrobacter These bacteria comprise a diverse group of rod, ellipsoidal, spherical, and spiral-shaped cells. At least one strain of itrobacter has been described that can grow by anaerobic respiration (denitrification). itrite-oxidizing bacteria are found in aerobic, but occasionally also in anaerobic, environments where organic matter is mineralized. They are widely distributed in soils, fresh water, brackish water, seawater, mud layers, sewage disposal systems, and inside stones of historical buildings and rocks. They are also found inside corroded bricks and on concrete surfaces such as in cooling towers and highway-automobile tunnels.

44 How does nitrogen reenter the atmosphere in the nitrogen cycle?

45 Through the fourth process called denitrification! (4) Denitrification (1) itrogen Fixation (3) Ammonification (2) itrification

46 What does denitrification do?

47 Denitrification converts nitrates (O 3 ) in the soil to atmospheric nitrogen ( 2 ) replenishing the atmosphere. itrogen in atmosphere ( 2 ) itrates (O 3 ) in Soil

48 How does the denitrification process work? itrates in soil

49 Denitrifying bacteria live deep in soil and in aquatic sediments where conditions make it difficult for them to get oxygen. The denitrifying bacteria use nitrates as an alternative to oxygen, leaving free nitrogen gas as a byproduct. They close the nitrogen cycle! itrogen in atmosphere closes the nitrogen cycle! ( 2 ) (O 3 ) Denitrifying bacteria live deep in soil and use nitrates as an alternative to oxygen making a byproduct of nitrogen gas.

50 Other ways that nitrogen returns to the atmosphere Emissions from industrial combustion and gasoline engines create nitrous oxides gas ( 2 O). Volcano eruptions emit nitrous oxides gas ( 2 O).

51 2 (a) (b) 2 O (4) Denitrification (1) itrogen Fixation (c) itrogen Cycle (3) itrification (2) Ammonification O 3 H 3 Ammonia is converted to nitrites and nitrates. itrates in Soil Organic nitrogen is converted to ammonium.

52 THE ITROGE CYCLE

53 ITROGE CYCLE Atmosphere Denitification: bacteria Biosphere itrogen fixation: bacteria lightning Absorption Hydrosphere Erosion Waste & Decomposition Lithosphere

54 itrogen- Fixing Bacteria in Root odules

55 Human Impacts ITROGE CYCLE Atmosphere et Effect: Increase in itrogen in water & soil itrogen fixation: industrial (fertilizer) combustion Biosphere Hydrosphere Increased Erosion Lithosphere

56 Schematic representation of the flow of nitrogen through the environment. The importance of bacteria in the cycle is immediately recognized as being a key element in the cycle, providing different forms of nitrogen compounds assimilable by higher organisms.

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58 MARIE ITROGE CYCLE

59 EFFECTS OF HUMA ACTIVITIES O THE ITROGE CYCLE We alter the nitrogen cycle by: Adding gases that contribute to acid rain. Adding nitrous oxide to the atmosphere through farming practices which can warm the atmosphere and deplete ozone. Contaminating ground water from nitrate ions in inorganic fertilizers. Releasing nitrogen into the troposphere through deforestation.

60 EFFECTS OF HUMA ACTIVITIES O THE ITROGE CYCLE Human activities such as production of fertilizers now fix more nitrogen than all natural sources combined. Figure 3-30

61 2 (a) (b) 2 O (4) (1) (c) itrogen Cycle (3) (2) O 3 Ammonia is converted to nitrites and nitrates. itrates in Soil H 3 Organic nitrogen is converted to ammonium.

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