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Biogeochemical Cycles I. Biogeochemical Cycles - Flow of chemical elements & compounds between living organisms & the physical environment Chemicals :

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Presentation on theme: "Biogeochemical Cycles I. Biogeochemical Cycles - Flow of chemical elements & compounds between living organisms & the physical environment Chemicals :"— Presentation transcript:

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2 Biogeochemical Cycles I. Biogeochemical Cycles - Flow of chemical elements & compounds between living organisms & the physical environment Chemicals :  Absorbed or ingested by organisms (food chain)  Returned to the soil, air, and water by: 1. Respiration3. Lithosphere 2. Excretion 4. Decomposition

3 Biogeochemical Processes 1.Regulate nutrients 2.Influence climate stability 3.Influence the purity of drinking water

4 Biogeochemical Cycles & the Earth A. Water Cycle Water Cycle B. Carbon Cycle Carbon Cycle C. Nitrogen Nitrogen D. Sulfur Sulfur E. Phosphorus Phosphorus

5 Water Cycle

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7 One estimate of global water distribution: Estimate of Global Water Distribution – Gleick, 1996 Volume (1000 km 3 ) Percent of Total Water Percent of Fresh Water Oceans, Seas, & Bays1,338, Ice caps, Glaciers, & Permanent Snow 24, Groundwater23, Fresh (10,530)(0.76)30.1 Saline (12,870)(0.94)- Soil Moisture Ground Ice & Permafrost Lakes Fresh (91.0)(0.007)0.26 Saline (85.4)(0.006)- Atmosphere Swamp Water Rivers Biological Water Total1,385,

8 One estimate of global water distribution: Estimate of Global Water Distribution – Gleick, 1996 Volume (1000 km 3 ) Percent of Total Water Percent of Fresh Water Oceans, Seas, & Bays1,338, Ice caps, Glaciers, & Permanent Snow 24, Groundwater23, Fresh (10,530)(0.76)30.1 Saline (12,870)(0.94)- Soil Moisture Ground Ice & Permafrost Lakes Fresh (91.0)(0.007)0.26 Saline (85.4)(0.006)- Atmosphere Swamp Water Rivers Biological Water Total1,385,

9 A. Water Cycle Vocabulary Review Evaporation  Liquid water is heated by sun & changed to water vapor Condensation  Water vapor is cooled and turns to liquid water droplets Precipitation  Any form of water falling from the sky

10 Water Cycle Vocabulary Review cont’ Recharge  Replenishing of the water table (usually by rain or melting snow) Runoff  Water that does not get absorbed by the ground and flows over an impermeable surface

11 Water Cycle Vocabulary Review cont’ Usage  When plants &/or animals remove water from the water table (ground water storage) Surplus  Occurs when the water table is full and usage is low (may cause floods) Defecit  Occurs when usage is high & the water table drops (drought)

12 1. Effects of Human Activities on Water Cycle Humans alter the water cycle by:  Withdrawing large amounts of freshwater  Clearing vegetation and eroding soils  Polluting surface and underground water  Contributing to climate change

13 Ex. Deforestation & Water Pollution

14 2. Carbon Cycle/Global Warming Affect the Water Cycle Increased ↑ temperature  increased ↑ precipitation, runoff, and soil moisture Feedback from increased temp: Increased ↑ cloud cover  (1) reflects light back into the atmosphere, so decreased temp (Upper Atmosphere) Increased ↑ cloud cover  (2) water vapor absorbs heat in the atmosphere, so ↑ increased temp (below clouds)

15 B. Carbon Cycle A biochemical circulation of the element carbon through the Earth System 1. Carbon is the building block of life

16 Carbon Cycle Cont’ 2. Carbon is changed into different compounds as it goes through the cycle  CH 4 = Methane Gas  CO 2 = Carbon Dioxide  C 6 H 12 O 6 = Carbohydrate (Sugar)

17 Carbon Cycle Cont’ 3. Carbon enters atmosphere as Carbon Dioxide (CO 2 ):  Exhaled by animals (Respiration)  O 2 +Food = CO 2 +H 2 O+Energy  Produced by decomposers

18 3. Carbon Dioxide Enters Atmosphere Cont’  Released by burning Wood & Fossil Fuels  Released by Volcanic Eruptions  Diffuses out of the Oceans

19 Carbon Cycle Cont’ 4. Carbon leaves atmosphere as CO 2 taken up by plants during photosynthesis (trees, grass, algae)  CO 2 +H 2 O+sunlight =C 6 H 12 O 6 (Food) +O 2  Carbon is stored in plant tissue as (C 6 H 12 O 6 ) Carbohydrates Ex. Glucose

20 Carbon Cycle Con’t 5. Animals eat plant Carbohydrates 6. Or algae/phytoplankton in oceans dies  Settles to bottom & becomes sediment o Lithification- Sediment hardens /compacts into rock

21 7. Ocean is known as a Carbon Sink because it stores carbon 8. Carbon dioxide from Atmosphere is dissolved in the ocean during wave action Forms bicarbonate & Calcium Carbonate (lime that forms sea shells) Carbon Cycle Con’t

22 Land Ocean Air 1. Burial – Limestone Formation 2. Fossilization Carbon Cycle HW Key Respiration Photosynthesis Respiration Lithification Oil NaturalGas Coal Shell formation Weathering & Erosion Burning & decay absorption & desorption volcanism Limestone

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24 9. Effects of Human Activities on Carbon Cycle Adding excess CO 2 to the atmosphere:  Burning fossil fuels  Clearing vegetation faster than it is replaced Figure 3-28

25 10. Relevance of Carbon Cycle to Climate Change CO 2 in atmosphere is increasing 0.4% a year (= 40% in 100 yr.) Increasing CO 2 causes increased temperatures. (Greenhouse effect) Heat captured by the atmosphere: a.CO 2 = 50% b.CH 4 = 20% c.CFCs = 15% d.NO 2, H 2 O, O 3 = 15%

26 Nitrogen  Important to living things because it is required to form amino acids  Building blocks of proteins Most living things cannot use nitrogen gas in their cells C. Nitrogen Cycle

27 Use nitrogen from the atmosphere to form ammonia (NH3) Form of nitrogen that plants can use Live in the soil and in the roots of legumes Ex of Legumes: peanuts, beans and clover 1. Nitrogen fixing bacteria

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30 2. Nitrifying bacteria make NH3 into: NO2 - = Nitrites NO3 - =Nitrates Most common form of nitrogen for plants, found in fertilizers

31 3. Animals get the nitrogen they need from proteins in the food they consume 4. Decomposers return the nitrogen to the soil in the form of ammonia which restarts the cycle Nitrogen Cycle Cont’

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33 5. Human 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

34 6. Effects of Human Activities on the Nitrogen Cycle Human activities such as production of fertilizers now fix more nitrogen than all natural sources combined. Figure 3-30

35 a. Effects of Increased Nitrogen 1.Loss of soil nutrients (Ex. calcium, potassium) 2.Acidification of rivers and lakes (fertilizers and combustion of coal) 3.Increases nitrogen oxides in the atmosphere (greenhouse gas—global warming) (reduce ozone—increasing UV penetration)

36 a. Effects of Increased Nitrogen Cont’ 4.Aids in spreading weeds into nitrogen poor areas (Eutrophication of lakes, ponds, streams)

37 Eutrophication The process by which a body of water acquires a high concentration of nutrients. Ex. of nutrients = phosphates and nitrates  Promotes excessive growth of algae  Algae die and decompose  High levels of organic matter and the decomposing organisms deplete the water of available oxygen  Causes the death of other organisms, such as fish

38 a. Effects of Increased Nitrogen Cont’ 5. Increasing nitrogen increases carbon fixation (linked to carbon cycle) 6. Increasing acidification increases weathering (increases rate of phosphorous cycle)

39 D. Sulfur Cycle Acidic fog and precipitation Ammonium sulfate Ammonia Sulfuric acid Water Sulfur trioxide Oxygen Hydrogen sulfide Sulfur dioxide Volcano Industries Dimethyl sulfide Ocean Metallic sulfide deposits Decaying matter Animals Plants Hydrogen sulfide Sulfur Sulfate salts

40 1. Key Compounds of the Sulfur Cycle a) Dimethyl sulfide Dimethyl sulfide b) Sulfur dioxide Sulfur dioxide c) Sulfur trioxide Sulfur trioxide d) Sulfuric Acid Sulfuric Acid e) Ammonium Sulfate Ammonium Sulfate f) Hydrogen Sulfide Hydrogen Sulfide

41 a. Dimethyl sulfide (CH 3 ) 2 S Emissions from Phytoplankton Occurs over oceans

42 b. Sulfur dioxide SO 2 Emissions:  Industries example : power plants  Volcanoes

43 c. Sulfur trioxide SO 3 Primary agent in acid rain SO 3 (l) + H 2 O (l) → H 2 SO 4 (l)

44 d. Sulfuric acid H 2 SO 4 Gas released by cutting onions combines with water in your eye to form Sulfuric acid Principal uses include:  Ore processing  Fertilizer processing  Oil refining

45 e. Ammonium Sulfate (NH 4 ) 2 SO 4 Made when ammonia reacts with H 2 SO 4 Uses:  Fertilizer  Agricultural spray - aids for water soluble pesticides

46 f. Hydrogen Sulfide H 2 S Emitted by volcanoes and hot springs Remains in atmosphere for 18 hours Changes into sulfur dioxide

47 1. Importance in Biochemical Cycle Nutrient for organisms Bacteria oxidize sulfur for energy (black smokers on ocean floor) Factor for plant productivity

48 2. Effects of Human Activities on the Sulfur Cycle Humans add sulfur dioxide to the atmosphere by:  Burning coal and oil  Refining sulfur containing petroleum  Convert sulfur-containing metallic ores into free metals such as copper, lead, and zinc releasing sulfur dioxide into the environment

49 E. Phosphorous 1. First isolated in 1669 by Hennig Brand, (German physician and alchemist)  Trying to make gold  Let urine stand for days  Boiled it down, captured gases & condensed them

50 Phosphorus cont’  Results = white, waxy substance that glowed in the dark  Brand had discovered phosphorus 2. Greek means "light bearer

51 1. Phosphorus cont’ 3. Essential to living organisms because it forms  DNA  RNA  ATP  Fats of cell membranes

52 Phosphorus cont’ 4. Not common in biosphere 5. Slowest biogeochemical cycle 6. Remains mostly on land in rock/soil minerals & in ocean sediments 7. Strictly a Lithosphere – Hydrosphere – Biosphere cycle (not Atmosphere)

53 Fig. 3-31, p. 77 Dissolved in Ocean Water Marine Sediments Rocks uplifting over geologic time settling out weathering sedimentation Land Food Webs Dissolved in Soil Water, Lakes, Rivers death, decomposition uptake by autotrophs agriculture leaching, runoff uptake by autotrophs excretion death, decomposition miningFertilizer weathering Guano Marine Food Webs

54 8. Effects of Human Activities on the Phosphorous Cycle Removal large amounts of phosphate from the earth to make fertilizer Reduce phosphorous in tropical soils by clearing forests Add excess phosphates to aquatic systems from runoff of animal wastes and fertilizers

55 II. Laws of Thermodynamics 1 st Law –energy/matter cannot be created nor destroyed, only changed from one form to another E= mc 2 Einstein

56 Laws of Thermodynamics 2 nd Law- when energy changes, it is converted from a more useful, more concentrated form to a less useful, less concentrated form  Energy can never be recycled completely. Some energy is lost, usually as heat or light

57 III. Intro Energy Cycle The movement of energy into & out of the Earth System The amount of energy that enters the system should = the amount of energy that is removed  Solar  Geothermal  Tidal

58 A. Solar Power % of energy that enters the Earth’s system is from the sun Drives the winds, oceans & waves Causes rocks to weather, forming soil

59 1. Albedo The percentage of energy that is reflected off the Earth without being changed  Forest = low albedo reflects 5-10%  Snow covered field = high albedo 80-90%

60 Energy Flow

61 100 Units of sunlight entering Earth’s Atmosphere 51 Units are absorbed by surface

62 B. Geothermal Energy.013% is energy from within the Earth  Friction & radioactive material Drives the movement of the plates Powers volcanoes, geysers, earthquakes & the rock cycle

63 C. Tidal Energy.002% is energy that results from the Sun & Moon’s pull on Earth’ s ocean Slows Earth’s rotation


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