Biogeochemical Cycles

1. Biogeochemical Cycles

2. Biogeochemical Cycles • There are 94 elements that are naturally occurring • Most of them find their way into biotic systems in some way • However it is important to know where they come from

3. Biogeochemical Cycles • We have done the basics of biogeochemical cycles • We talked about the water cycle and how it redistributes water around the planet • This cycle changes water to different states of matter and moves it around • These cycles can be local or global

4. Biogeochemical Cycles • However there are many different biogeochemical cycles • The other major cycles are the carbon cycle, nitrogen cycle and the phosphorous cycle • These cycles all move nutrients around the planet in different forms

5. Biogeochemical Cycles • Each of these cycles use organic matter and abiotic reservoirs to house different forms of chemicals • Organic matter is tissue that makes up living systems • Abiotic reservoirs are areas outside of living things that will store the chemical

6. Carbon Cycle • Carbon is the major ingredient on all organic matter • Remember that organic chemistry deals with carbon based chemistry • It is present in the atmosphere, soil and (to a lesser degree) our water

7. Carbon Cycle • Understanding how the carbon cycle works is important because it is one of the major causes of climate change • Carbon in the atmosphere takes the form of CO2 • CO2 is one of the major green house gasses due to its structure and abundance

8. How It Works • The carbon cycle is based on two major reactions • Photosynthesis • It is also based on the reaction that is the reverse of photosynthesis • Cellular Respiration

9. How It Works • Since there is no starting point, lets start with carbon in the atmosphere • This carbon in the form of CO2 is a gas • That gas is taken in by cells of green producers

10. How It Works • The CO2 will then change forms to sugars • Basic structure of C6H12O6 • This form of carbon will then be passed to consumers that eat leaves, fruits or bark of the plant • The carbon will be incorporated to their organic matter

11. How It Works • At this point larger consumers will consume the smaller consumers • These organisms will be converted to organic matter inside the predator

12. How It Works • While in the consumer system, organisms are releasing waste, breathing and dying • Breathing releases CO2 back into the atmosphere • Releasing waste and dying introduces carbon to the soil

13. How It Works • Once carbon is in the soil, it is attacked by decomposers • The decomposers breakdown the detritus and release CO2 back to the atmosphere • This competes the cycle

14. Human Input • However, humans are greatly affecting this cycle • We are releasing large amounts of CO2 into the atmosphere by humans tapping into decomposing or decomposed organisms

15. Human Input • Fossil fuels are organisms that have decomposed and have been buried at different depths • Depending on the pressure, and heat at where they are buried determines the type of fossil fuel • All of these fuels contain a large amount of carbon

16. Composition of Air • Air is composed of different compounds and elements • It has around around 78% Nitrogen • In the form of (N2) • It has around 21% oxygen • In the form of (O2) • It is composed of around 1% other compounds • Argon • CO2

17. Composition of Air • This makes nitrogen the most common gas in our environment • You would think that it would be abundant and easy to use • However nitrogen is a difficult material to convert from a gas

18. Nitrogen Fixation • In order to have nitrogen in a useable form it has to change from the N2 in air • The nitrogen must be put in a usable form • One useable form is ammonia

19. Nitrogen Fixation • In order for a N2 to be converted to NH3 there has to be a way for it to change • Nitrogen will not spontaneously convert to ammonia • There needs to be a process • The process of turning N2 into useable NH3 is called nitrogen fixation

20. Mycorrhizal Bacteria • In soil the place that has the most life is right next to the roots of plants • This is because many microorganisms live in this area • We call this area the rhizosphere

21. Mycorrhizal Bacteria • This area around the roots contains a wildly diverse ecosystem • Fungi • Bacteria • Nematodes • Protozoa • A gram of soil from the rhizosphere can contain 50 million to 1 billion microorganisms

22. Mycorrhizal Bacteria • Bacteria that live right around the roots are called mycorrhizal bacteria • These bacteria are close enough to interact with the plant and can form a symbiotic relationship with the plant

23. Mycorrhizal Bacteria • Legumes are plants with dry fruit that have a symbiotic relationship with mycorrhizal bacteria • They contain a simple dry fruit • They contain • Many Beans • Peanuts • Alphalpha

24. Mycorrhizal Bacteria • Most legumes can support bacteria that fix nitrogen • These bacteria form nodes or “bumps” on the roots of these plants • These bacteria fix nitrogen

25. Nitrogen Cycle • Once again because it is a cycle, there is no beginning or end to the nitrogen cycle • Lets start with atmospheric nitrogen as N2 • It is taken in by nitrogen fixing bacteria and is converted to ammonia (NH3) • It can also be converted to NO or NO2 by lightning

26. Nitrogen Cycle • NO and NO2 can be used by a plant • NH3 needs to pick up a free hydrogen to become ammonium (NH4) • NO, NO2 and NH4 can all be used by a plant • They are incorporated by the plant

27. Nitrogen Cycle • The rest we know… • Consumers eat the plants and release waste and die • Other consumers eat the primary consumers and release waste and die • A large quantity of nitrogen is in introduced to the soil

28. Nitrogen Cycle • When in the soil decomposers will use the nitrogen • Also bacteria known as denitrifiers will take in NH3 from the soil and release it as N2 • This N2 finds its way back tot the atmospheric reservoir

30. Human Impact • Humans can greatly impact this cycle by adding nitrogen to the soils • Humans do this by adding fertilizer to fields, crops and farms • This greatly increases the amount of nitrogen in the soil

31. The Human Impact • Humans adding nitrogen can be very harmful • Excess nitrogen can be captured in runoff • This runoff is then carried to the ocean were it causes an algae bloom

32. The Human Impact • An algae bloom is very destructive to an ecosystem • It chokes the life out of all manner of sea life • Without this sea life, there are no primary consumers to feed secondary consumers • It can wipe out large sections of open water

33. The Human Impact https://www.youtube.com/watch?v=OUeAMzoKNWg https://www.youtube.com/watch?v=5X8ZiycqIlY

34. Erosion • Have you ever looked at the amount of rocks on the earth? • There are a really large number of rocks that contain minerals that are needed in living systems • Since most organisms cannot digest solid rock, the minerals in them have to be unlocked in other ways

35. Erosion • Rocks can be slowly broken down over time if they undergo the process of erosion or weathering • This is the gradual breakdown of the rock into much smaller sizes • These smaller rocks will continue undergo erosion and weathering

36. Erosion • Once these rocks are broken up sufficiently they can be incorporated into the soil • The soil then takes on the properties of the rocks that compose it • This is why there are different soil types in different areas

37. Phosphorous Cycle • The erosion of rock releases one of the most limited nutrients into the soil • Phosphorous is a very limited nutrient in most ecosystems • Remember it is a central part of DNA, ATP and Phospholipids

38. Phosphorous Cycle • However when rocks erode they release the nutrient into the soil • This allows access of phosphorus to plants and other producers • They will incorporate this into their living tissue

39. Phosphorous Cycle • Consumers then will eat the producers • Other consumers will then eat the primary consumers • The consumers will use the phosphorous in their living tissues

40. Phosphorous Cycle • The consumers will then release waste or die and return phosphorous back into the soil • Decomposers will then use that phosphorous in their tissues

41. Back to Rock • The cycle would not be complete if phosphorous was not going back to rock • Sediment and soil that washes into waterways will settle at the bottom • These soils and sediments will find a resting place at the bottom of a lake, river or ocean

42. Back to Rock • The sediments will eventually be packed down by layers of sediment on top of them to create sedimentary rock • Eventually this rock will find its way to the surface and will be the rock that is eroding and weathering