Cycling of matter

1. Cycling of matter IB Syllabus: 2.5.4 Ch. 4

2. Syllabus Statements • 2.5.4: Describe and explain the transfer and transformation of materials as they cycle within an ecosystem

3. Biogeochemical cycles • Nutrients needed for life are continuously cycled between living and nonliving things • Life  Earth  Chemical cycles • Driven by incoming solar energy • Connect past – present – future by recycling chemical compounds • Oxygen, Carbon, Nitrogen, Phosphorous, and water

5. Water Cycle • Collects, purifies and distributes earth’s constant water supply • Evaporation – converts water into vapor • Transpiration – evaporation from plant leaves • Condensation – vapor to liquid • Precipitation – rain, sleet, snow, hail • Infiltration – movement of water into soil • Percolation – flow of water to aquifers • Runoff – movement of water over land surface

6. Hydrologic cycle

7. Water cycle • Sun powers the cycle – 84% vapor from ocean • Warmer air holds more water • Relative humidity = amount of water vapor in a mass of air expressed as a % of the maximum the air could support at that temp • Wind and air masses transport water around the earth

8. Water cycle II • Precipitation – needs condensation nuclei to occur • Soil dust, volcanic ash, smoke, sea salt, particulates • Some locked in glaciers, most into oceans as surface runoff • Runoff sculpts earth’s surface & transports nutrients • Water purification happens at many steps

9. Hydrologic Cycle

10. Human Influences • Withdrawing large quantities of fresh water from surface and ground water • Aquifer depletion and saltwater intrusion • Clearing vegetation for agriculture, mining, construction • Increase runoff, flooding, erosion, Decrease infiltration • Modifying water quality • Adding nutrients, changing natural processes

13. Carbon cycle • “C” is the basic building block of life • Global gaseous cycle based on CO2 • Producers remove CO2 from the atmosphere in photosynthesis • Respiration of organisms puts CO2 back into atmosphere • Organic carbon stored in living tissues and fossil fuel deposits

15. Terrestrial Carbon cycle

16. Carbon storages • Organisms store most of the carbon • organic compounds • Sedimentary rocks such as limestone • Carbon reenters cycle when sediments dissolve naturally or by acid rain • Oceans • Gas dissolves into ocean at surface • Removed by marine algae in photosynthesis • Marine organisms • Reaction of CO2 with Ca in organisms to produce CaCO3 for shells and

17. Aquatic Carbon Cycle

18. Human effects • Adding Carbon to the Atmosphere • Clearing trees and plants that absorb CO2 through photosynthesis • Burning fossil fuels and wood increasing CO2 • Enhance the greenhouse effect • Raise sea level • Disrupt food production • Destroy habitats

19. Nitrogen cycle

20. 1. Nitrogen Fixation • Specialized bacteria convert atmospheric N2 into NH3 • N2 + 3 H2 2 NH3 Done by • Cyanobacteria – in soil and water • Rhizobium – bacteria living in root nodules of a variety of legume plants

21. 2. Nitrification • A two step process • Ammonia in soil converted to nitrite and nitrate • Aerobic bacteria complete this process • NH3NO2- (toxic to plants) • NO2-NO3- (easily taken up by plants as nutrient

22. 3. Absorption / Assimilation • Plant roots absorb inorganic nitrogen ions • nitrates, ammonium • Ions used to make nitrogen containing organic molecules • DNA, amino acids, proteins • Animals get nitrogen by eating plants or other plant-eating animals

23. 4. Ammonification • After N has been used in living things and it leaves as waste or death… • Bacterial decay results • Producing • Simpler inorganic compounds like NH3 • Water soluble salts containing NH4+

24. 5. Denitrification • Anaerobic bacteria in waterlogged soils and bottom sediments • Convert nitrogen compounds back into gas forms and release into the atmosphere NH3NO2- N2   NH4+ NO3- N2O

25. Human effects on the N-cycle • Inputs of commercial inorganic fertilizer • Adding NO to the air through combustion of fuels • Enters water cycle  Acid Rain • Removing “N” from the crust by mining • Removing “N” from soil • Harvest crops, irrigation, deforestation • Adding “N” to aquatic systems from runoff

27. The Phosphorous cycle • Through water  organisms  earth’s crust • Very little in the atmosphere • Found as phosphate salts in terrestrial rocks and ocean sediments • Into organisms by uptake & assimilation by plants, consumption & assimilation by animals, then animal waste returns it to water or to the land (guano) • Often a limiting factor in plant growth both terrestrial and aquatic

28. Phosphorous cycle

31. Human effects • Mining large amounts of phosphate rock • Inorganic fertilizers, Detergents • Reducing available phosphate in tropical forests by removing trees • Soil nutrients washed away w/out trees • Adding excess phosphate to aquatic systems • Runoff of animal waste, commercial fertilizer from farmland, municipal sewage discharge

32. Florida Phosphate mining

33. The sulfur cycle • Most “S” stored underground in rocks and minerals including salts in ocean sediment • Enters the atmosphere from volcanoes, sea spray, decomposition in aquatic habitats • Marine algae may produce DMS sulfur compounds in large quantities • In atmosphere it may mix into hydrologic cycle to form sulfuric acid – acid rain

34. Sulfur cycle

35. Human effects • Burning “S” containing coal and oil for electricity production • 2/3 of human SO2 inputs • Refining “S” containing petroleum into gasoline, heating oil, etc. • Smelting of “S” compounds of metallic minerals producing pure metals • Copper, Lead, Zinc

36. Cycle types • With all cycles common features allow grouping • Groups based on storages • Sedimentary cycle – major storage in the ground • E.x. phosphorous cycle • Atmospheric cycle – major storage in the atmosphere • E.x. nitrogen cycle

37. You should be able to create a flow diagram of Carbon, Water and Nitrogen cycles

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