1. Abiotic Cycles in the Biosphere
Chapter 13

2. Abiotic Cycles in the Biosphere
We can classify everything in our world into one of two very broad categories:
Biotic (meaning alive or previously alive)
Abiotic (meaning non-living)

3. Biotic Factors
Anything alive or previously living is classified as a biotic factor.
Examples could include: People, bacteria, plants, fungi, insects, snakes, reptiles, and any other living things.
A tiger beetle (the world’s fastest land animal relative to body size) poised on a deciduous leaf.

4. Abiotic Factors
Anything that is not currently alive and has never been alive, is classified as an abiotic factor.
Examples could include: Rocks, water, minerals, sunlight, etc.

5. Think about this…
A water molecule in your body right now may have once been a water molecule in the body of a pioneer crossing Oklahoma’s plains, a trilobite at the bottom of the sea, or a grazing brontosaurus!

6. Victoria Falls, Zambia, Africa
Abiotic Factors
Though abiotic factors are not alive, they are crucial to living things & life on earth.
Ex: Without sunlight life on earth would quickly perish. Likewise, w/o water life would soon vanish also.
Victoria Falls, Zambia, Africa

7. Victoria Falls, Zambia, Africa; Largest Waterfall on Earth.

8. The Hydrological (or Water) Cycle
The hydrological cycle has 6 main components:
Precipitation
Runoff
Infiltration
Evaporation
Transpiration
Condensation
Infiltration into soil

9. The Hydrological (or Water) Cycle
Precipitation
Water that reaches the earth’s surface as rain, snow, sleet, or hail is called precipitation.
The earth receives a tremendous amount of precipitation each year. If all of it were to fall on Oklahoma at once, we would be covered over 2,500 meters deep!

10. The Hydrological (or Water) Cycle
2. Infiltration
When precipitation reaches the earth’s surface, some of it may seep into the ground; a process known as infiltration.
Water that seeps underneath the earth’s surface is called groundwater.

11. The Hydrological (or Water) Cycle
2. Infiltration (cont.)
If groundwater seeps down to a layer of rock that it cannot pass through, it will start traveling laterally (parallel to the rock layer).
Such zones of traveling groundwater are called aquifers.

12. The Hydrological (or Water) Cycle
2. Infiltration (cont.)
Aquifers can return water to the surface by feeding lakes & rivers, or even flowing into oceans.
Humans can also take advantage of aquifers by tapping into them with wells for drinking water or water for crops and livestock.

13. The Hydrological (or Water) Cycle
2. Infiltration (cont.)
The Ogallala aquifer is one of the largest aquifers on earth & runs underneath Oklahoma, Texas, Kansas, and Nebraska.
Aquifers can become depleted if the water is taken out of them faster then they can recharge.

14. The Hydrological (or Water) Cycle
3. Runoff
When precipitation falls at a greater rate than the ground can absorb it, it will run over the surface of the ground. This water is known as runoff.
Runoff is a major source of topsoil erosion in Oklahoma (and many other mid-western states).

15. The Hydrological (or Water) Cycle
3. Runoff (cont.)
Runoff water will eventually find its way to streams, rivers, lakes, or oceans.

16. The Hydrological (or Water) Cycle
4. Evaporation
Evaporation is the process by which water from oceans, lakes, streams, rivers, and even the land returns to the atmosphere.
Many factors can effect the rate of evaporation in an area including: air temperature, amount of water vapor in the air, etc.

17. The Hydrological (or Water) Cycle
5. Transpiration
Water can also return to the air through a process called transpiration.
During transpiration, water escapes from the leaves of plants (through the stomata’s) into the atmosphere. Sometimes scientists refer to evaporation & transpiration as a single process: evapotranspiration.

18. The Hydrological (or Water) Cycle
5. Transpiration (cont.)
One of the reasons that tropical rainforests get so much rainfall is that evapotranspiration pumps millions of gallons of water into the atmosphere around them.

19. The Hydrological (or Water) Cycle
6. Condensation
Condensation is the change of water from a gaseous to a liquid state.
After evaporation returns water to the air, the water vapor can condense and form clouds.

20. The Hydrological (or Water) Cycle
6. Condensation
When so much water vapor condenses that the cloud can no longer hold it, precipitation will be released. (It’s gonna rain, baby!)

21. The Hydrological (or Water) Cycle
Key processes in the hydrological cycle are evaporation, transpiration, and precipitation.

22. The Hydrological (or Water) Cycle
The hydrological cycle has a huge impact on earth by weathering rocks, translocating (moving) soil, and even moderating air temperatures!

23. The Hydrological (or Water) Cycle
Remember, oceans & large bodies of water have a moderating effect on the climates of nearby landforms.
This is the major reason that L.A. and Oklahoma City have vastly different climates though they are at basically the same latitude.

24. The Hydrological (or Water) Cycle
The nearby Pacific Ocean protects L.A. from large fluctuations in temperatures, whereas Oklahoma City has no such body of water to moderate its climate.

25. The Hydrological (or Water) Cycle
The hydrological cycle also affects climate through water’s ability to trap or reflect sunlight energy.
During the day, clouds reflect some of the sun’s energy back into space, resulting in cooler temperatures on the ground.

26. The Hydrological (or Water) Cycle
At night clouds act as an insulating blanket, preventing heat in the atmosphere from escaping back into space.
Also, polar ice caps & glaciers reflect sunlight (& thus heat energy) back out into space, causing much colder temperatures near the poles.

27. Clear your desk to take a quiz!!! SURPRISE!!!!

28. The Carbon Cycle
Photosynthesis and cellular respiration are the two main steps in the carbon cycle.

29. The Carbon Cycle
Carbon circulates through the biosphere by way of the carbon cycle.
Carbon is a vital element that is necessary for life. Recall that we are known as “carbon-based” life forms.

30. The Carbon Cycle
As we study biology, carbon and “organic molecules” comes up often.
This is because carbon forms the backbone for all organic compounds, and is crucial for life on earth.

31. The Carbon Cycle
The most common carbon containing compound on earth is cellulose, and the most carbon containing compound in the atmosphere is CO2.
How much of the earth’s atmosphere do you think might be CO2?

32. Earth’s Atmosphere is composed of:
*Note: these numbers add up to 101% because they have been rounded slightly.
78% Nitrogen
21% Oxygen
1% Water Vapor
0.93% Argon
0.038% CO2
0.0020% Other trace gases

33. The Carbon Cycle Many sources release CO2 into the atmosphere:
Animals release it during cellular respiration
Decomposition of dead plants & animals
Volcanic eruptions
Burning of fossil fuels such as coal, gasoline, and oil.

34. The Carbon Cycle So how is CO2 taken OUT of the atmosphere?
Photosynthetic organisms (such as plants) “fix” CO2 into sugar molecules.

35. Terminology:
The term “fix” does not mean that plants somehow “repair” the CO2. In biology, “fixing” means to take an abiotic factor and change it into a form that can be used for life.

36. The Carbon Cycle
Scientists estimate that each year photosynthetic organisms remove about 70 billion tons of carbon from the atmosphere to fix into sugars.
Which means lots of sugar for my coffee!

37. The Nitrogen Cycle
The element nitrogen is an essential component of DNA, RNA, & proteins, so the nitrogen cycle is vital to life.
Recall that about 78% of the atmosphere is made up of nitrogen gas. HOWEVER, most organisms can’t utilize nitrogen in its gaseous state (N2 gas).

38. The Nitrogen Cycle
Usable nitrogen compounds are in far shorter supply than usable forms of water or carbon, so scientists say that nitrogen compounds are a limiting factor in the environment.
A limiting factor establishes the upper limit to the amount of organisms that can live in a certain place.

39. A Limiting Factor
Ex: Soil with high amounts of nitrogen compounds can support more plants growing in it than soil with low amounts of nitrogenous compounds. Only a few plants can grow in the nitrogen poor soil because there is not enough nitrogen to support them all.
Thus, the amount of nitrogen in the soil LIMITS the number of plants that can grow there.

40. The Nitrogen Cycle
Most of the useable nitrogen supply is produced by nitrogen fixing bacteria which live in the roots of plants called legumes.
Legumes include such plants as peanuts, soybeans, alfalfa, & clover.

41. The Nitrogen Cycle
Nitrogen fixing bacteria convert nitrogen gas (N2) into compounds that contain ammonia (NH3).
Bacteria can also convert the newly made ammonia into nitrite (NO2) and nitrate (NO3) compounds, a process called nitrification. Plants can then absorb and utilize these compounds.

42. The Nitrogen Cycle
After an organism dies, bacteria and fungi degrade the nitrogen compounds back into ammonia, a very STINKY process called denitrification.

43. The Nitrogen Cycle
Some plant species use some of this newly made ammonia directly; nitrogen fixing bacteria can fix some of the remaining ammonia into nitrite and nitrate compounds again (nitrification) for absorption by plants, and a little of the ammonia will completely decompose & return to the atmosphere as nitrogen gas (N2)

44. The Nitrogen Cycle
Nitrogen-fixing bacteria are important in the nitrogen cycle because they fix nitrogen gas into a usable form of nitrogen for plants.

45. The Phosphorus Cycle
Phosphorus is essential to the formation of bones, teeth, and molecules like DNA and RNA.
Plants get the phosphorus they need from the soil. Animals, in turn, get phosphorus from consuming plants or other animals.

46. The Phosphorus Cycle
In the phosphorus cycle, phosphorus moves from phosphate deposited in rock, to the soil, to living organisms, and finally to the ocean. Phosphorus is a limiting nutrient much like nitrogen.

47. The Phosphorus Cycle
Phosphorus is also added to the soil when organisms excrete excess phosphorus in their wastes, as well as when they die and decompose.
Phosphorus is also commonly added to fields as fertilizer, which can then runoff into streams and groundwater.

48. Human Intervention
Recent human activities have changed the phosphorus and nitrogen cycles dramatically.
Scientists estimate that human activities are now responsible for roughly half the nitrogen fixation on the Earth.

49. Human Intervention This situation came about in two ways:
Widespread use of commercial fertilizers (which contain nitrates & phosphates)
Widespread planting of legumes such as soybeans & alfalfa.

50. Human Intervention
As a result, the natural process of denitrification cannot keep pace with the quantities of nitrates building up in the environment.
This buildup of nitrogen containing compounds poses some serious problems.

51. Human Intervention
High levels of nitrates (as well as phosphates) can end up in groundwater or aquifers, polluting the water supply.
Rivers, lakes, and oceans are also experiencing increased levels of nitrogen and phosphorus.

52. Human Intervention
The increase in nitrogen nutrients can cause a rapid overgrowth of algae called an “algal bloom”
For a short time this is good because the algae produces more oxygen & provides more food for local marine animals. HOWEVER…

53. Human Intervention
When the algae use up all of the nutrients, they die and begin to decompose.
The decomposition of the algae releases CO2 into the water. The bigger the bloom, the more CO2 is released during decomposition.
An algal bloom off the Ireland coast.

54. Human Intervention
The decomposing algal blooms can release so much CO2 into the water that it suffocates all the local marine life!

55. An algal bloom in the Barents Sea
Human Intervention
The name for overgrowth caused by oversupplying a limiting nutrient (such as nitrogen or phosphorus) is eutrophication.
An algal bloom in the Barents Sea