1. Cycling of Matter
SEV1. Obtain, evaluate, and communicate information to investigate the flow of energy and cycling of matter within an ecosystem.

2. Matter Cycling in Ecosystems
Nutrient or Biogeochemical Cycles
Natural processes (Natural Services) that recycle nutrients in various chemical forms in a cyclic manner from the nonliving environment to living organisms and back again

3. Nutrient Cycles
Water
Carbon
Nitrogen
Phosphorus
Sulfur

4. Biogeochemical Cycle Locations
Hydrosphere
Water in the form of ice, liquid, and vapor
Operates local, regional, and global levels
Atmosphere
Large portion of a given element (i.e. Nitrogen gas) exists in gaseous form in the atmosphere
Sedimentary
The element does not have a gaseous phase or its gaseous compounds don’t make up a significant portion of its supply
Operates local and regional basis

5. Nutrient Cycling & Ecosystem Sustainability
Natural ecosystems tend to balance
Nutrients are recycled with reasonable efficiency
Humans are accelerating rates of flow of mater
Nutrient loss from soils
Doubling of normal flow of nitrogen in the nitrogen cycle is a contributes to global warming, ozone depletion, air pollution, and loss of biodiversity
Isolated ecosystems are being influenced by human activities

6. Carbon Cycle

7. Carbon Cycle Role of Carbon [C]?
Building block of organic molecules (carbohydrates, fats, proteins, & nucleic acid) – essential to life
Currency of energy exchange – chemical energy for life stored as bonds in organic compounds
Carbon dioxide (CO2) greenhouse gas – traps heat near Earth's surface & plays a key role as "nature's thermostat"

8. Carbon Cycle Main processes:
Movement in atmosphere: atmospheric C as CO2 (0.036% of troposphere);
Primary production: photosynthesis (= carbon fixation) moves C from atmosphere to organic molecules in organisms;
Movement through food web: C movement in organic form from organism to organism;
Aerobic respiration: organic molecules broken down to release CO2 back to atmosphere;
Combustion: organic molecules broken by burning down to release CO2 back to atmosphere;
Dissolving in oceans: C enters as to form carbonate (CO32–) & bicarbonate (HCO3–);
Movement to sediments: C enters sediments, primarily as calcium carbonate (CaCO3);

9. Carbon Cycle Respiration—organisms breathe and give off CO2
Photosynthesis—plants take in CO2, water and energy from the Sun to produce carbohydrates
Living things act as exchange pools for carbon

10. Carbon Cycle
Carbon locked in the plant carbohydrates passes to other organisms through food chain
When organisms die, bodies decompose through activities of fungi and bacteria in soil, which releases CO2.

11. Carbon Cycle
Dead organisms buried and subjected to extreme heat and pressure becomes oil, coal and gas (fossil fuels)
Combustion of fossil fuels releases carbon into atmosphere
Volcanic action also releases carbon

12. Carbon Cycle Carbon Reservoirs: Oceans because CO2 is soluble in water
Earth’s rocks that contain carbon in the form of calcium carbonate (marble and limestone)

13. Carbon Cycle Human impacts:
Removal of vegetation: decreases primary production (decreases carbon fixation)
Add carbon and CO2 by burning fossil fuels, wood and other biomass material (slash and burn in tropics)
Increased CO2 can alter global climate

14. Water Cycle

15. Water Cycle Main processes:
Evaporation: conversion from liquid to vapor form (surface to atmosphere).
Transpiration: evaporation from leaves of water extracted from soil by roots & transported through the plant (surface to atmosphere).
Movement in atmosphere: transport as vapor.
Condensation: conversion of vapor to liquid droplets.
Precipitation: movement as rain, sleet, hail, & snow (atmosphere to surface).
Infiltration: movement into soil.
Percolation: downward flow through soil to aquifers.
Flow in aquifers: belowground flow of water.
Runoff: surface flow downslope to ocean or other body of water.

16. Water Cycle Human Impact:
Withdrawing large amounts of fresh water that is often accompanied by saltwater intrusion and groundwater depletion.
Clearing of land for agriculture or habitation
Increase runoff, flood risks, soil erosion, landslides
Decrease infiltration
Augmenting pollutions by
Nutrients through runoff
Disturbing natural processes
Introducing infectious agents

17. Nitrogen Cycle

18. Nitrogen Cycle Role of Nitrogen (N)?
Building block of various essential organic molecules – especially proteins & nucleic acids
Limiting nutrient in many ecosystems – typically, addition of N leads to increased productivity

19. Nitrogen Cycle Needed to make amino acids, proteins, DNA and RNA
Nitrogen stores include organic matter in soil and oceans
78% of atmosphere is nitrogen
Atmospheric nitrogen is not in form that can be used directly by most organisms

20. Nitrogen Cycle Plants absorb N through nitrate ions and ammonium ions
Animals absorb N by consuming organic matter
Decomposers convert ammonia to ammonium compounds through mineralization

21. Nitrogen Cycle Processes
1. Nitrogen fixation —converts N2 to NH3
By specialized bacteria (cyanobacteria and actinomycetes in soil and Rhizobium bacteria in root systems of legumes)
N2 + 3H2  2NH3 (ammonia)
2. Nitrification —ammonia converted by aerobic bacteria to nitrite ions then to nitrate ions
NH3 by aerobic bacteria  NO2- by bacteria NO3-

22. Nitrogen Cycle Processes
3. Assimilation—plants absorb ammonia (NH3), ammonium ions (NH4) and nitrate ions (NO3) through their roots which are then eaten by heterotrophs Plant roots + NH3 + NH4+ + NO3- → DNA + amino acids + proteins 4. Ammonification—decomposing bacteria convert dead organisms and other waste to ammonia or ammonium ions that can be reused by plants Organic material → NH3 + NH4+

23. Nitrogen Cycle Processes
5. Denitrification—specialized bacteria convert NH3 and NH4+ into NO2- and NO3- and then into N2 and released into the atmosphere
NH4+ + NH3 → NO2- + NO3- → N2 + N2O (nitrous oxide)

24. Nitrogen Cycle Human Impact
Burning fuels lead to nitric acid/acid rain
Depleting N from soil by over-planting
Leaching from soil by irrigation and into groundwater
Agricultural runoff leads to eutrophication (aerobic decomposers break down aquatic bloom, depleting water of dissolved oxygen)
Discharge of municipal sewage
N-rich fertilizer

25. Phosphorous Cycle

26. Phosphorus Cycle Role of Phosphorus (P)?
Essential nutrient for plants & animals – especially building block for DNA, other nucleic acids (including ATP; ATP stores chemical energy), various fats in cell membranes (phospholipids), & hard calcium–phosphate compounds (in bones, teeth, & shells)
Limiting nutrient in many ecosystems – typically, addition of P leads to increased productivity, especially for fresh water aquatic systems.

27. Phosphorous Cycle
P is found in sedimentary rock, not in the atmosphere
Found in form of phosphate ion or hydrogen phosphate ion
Production not dependent on bacterial action
P released from terrestrial rock by weathering and action of acid rain
Slow process
Becomes dissolved in soil water and is then taken up by plant roots

28. Phosphorus Cycle Main processes:
Weathering: P slowly released from rock or soil minerals as phosphate (P043-), which dissolves in H20 & is readily leached
Uptake: by plants to form organic phosphates
Movement through food web: nucleic acids (including DNA & ATP), certain fats in cell membranes (phospholipids), bones/teeth/shells (calcium–phosphate)
Break down of organic forms: to phosphate (P043-) by decomposers
Leaching: P043- from soil
Burial in ocean sediments: not cycled in short time scale, only over geologic time

29. Phosphorous Cycle Human Impact Mining, scarring land
Clear cutting tropical areas for agriculture
Runoff of animal waste and fertilizers and discharge of municipal sewage plants
Stream runoff causes it to accumulate in lakes increasing growth of bacteria and plants, blocking sun, decrease oxygen, killing life

30. Sulfur Cycle

31. Sulfur Cycle Role of Sulfur (S)?
Most found in underground rocks and deep oceanic deposits
Released through weathering, gases released from sea floor vents and volcanic eruptions and venting
Most enters atmosphere through burning fossil fuels such as coal and oil

32. Sulfur Cycle Makes up proteins and vitamins
Dissolves in water that plants absorb through roots in form of sulfates
Animals obtain sulfur from eating plants
Most found in rocks and salts or oceanic sediments
Some in atmosphere from natural and human activities

33. Sulfur Cycle Main processes:
Storage in rocks: much of Earth's S is in rock form (e.g., iron disulfides or pyrites) or minerals (sulfates)
Atmospheric input from volcanoes, anaerobic decay, & sea spray: S enters atmosphere in form of hydrogen sulfide (HS) & sulfur dioxide (SO2), & sulfates (SO42–)
Combustion: sulfur compounds released to the atmosphere by oil refining, burning of fossil fuels, smelting, & various industrial activities
Movement through food web: movement through food web & eventual release during decay

34. Sulfur Cycle Natural Human Volcanic eruptions
Certain bacterial functions
decay
Human
Industrial processes producing SO2 and H2S gases (mostly burning coal and oil)

35. Sulfur Cycle Human Impact
Burning of coal and oil and petroleum refining release twice as much SO2 into troposphere as nature
Smelting of metal ores containing sulfur
Using sulfuric acid in industrial processes and manufacture
Refining petroleum

36. Nutrient Storehouses
Major nonliving & living storehouses of elemental nutrients.

37. Nutrient Cycling & Sustainability
Are ecosystems self–contained?
Immature natural ecosystems tend to have major shifts in energy flow & nutrient cycling
Over time ecosystems tend to reach an equilibrium with respect to energy flow & nutrient cycling, such that these ecosystems appear self–contained
However, there is considerable exchange of water & nutrients of ecosystems with adjacent ecosystems
Human disturbance (clear cutting, clearing, etc.) can cause major loss of nutrients

38. Nutrient Cycling & Sustainability
How does nutrient cycling relate to ecosystem sustainability?
The law of conservation of matter enables us to understand major nutrient cycles, and observe that given time natural ecosystems tend to come into a balance wherein nutrients are recycled with relative efficiency
Modification of major nutrient cycles may lead to shift in ecosystems, such that current ecosystems are not sustainable
Developing a better understanding of energy flow & nutrient cycling is critical to understanding the depth of environmental problems
All things come from earth, and to earth they all return.
–– Menander (342–290 B.C.)