1. Biogeochemical cycles
AN Introduction to
Biogeochemical cycles

2. What is a Biogeochemical Cycle?
A biogeochemical cycle is the movement of a particular chemical through the biological and geological parts of an ecosystem.
Matter cycles in and out of an ecosystem.

3. Key Biogeochemical Cycles: Elements and Compounds
Carbon
Oxygen
Water
Nitrogen
Phosphate

4. Cycling Oxygen in Living Systems
The main processes involved in the oxygen cycle are photosynthesis and respiration.
Oxygen cycles indirectly through an ecosystem by the cycling of other nutrients.

5. The Water Cycle (Hydrologic Cycle) :
The water cycle involves the movement of water back and forth from Earth’s surface to the atmosphere.
The hydrologic, or water, cycle is the circular pathway of water on Earth.
Organisms all have bodies made mostly of water.
Remember water can exist in 3 states:

6. The Water Cycle: 3 basic Steps
Water on the Earth’s surface is heated by the sun and evaporates.
Water rises into the upper atmosphere, cools, condenses, and forms clouds.
Water falls back to the surface as precipitation (rain, snow, sleet, or hail).

7. The Water Cycle: Key concepts
Most precipitation falls back into the oceans, lakes, rivers, and streams.
Water in the atmosphere is completely replaced once every 8 days
Water on this planet can be stored in any one of the following reservoirs: atmosphere, lakes, rivers, oceans, groundwater, soil, and/or glaciers.

8. The Hydrologic Cycle

12. Carbon: The Building Block of Life
The carbon cycle moves carbon from the atmosphere, through the food web, and returns to the atmosphere.
Carbon is emitted by the burning of fossil fuels.
Some carbon is stored for long periods of time in areas called carbon sinks.

14. The Carbon Cycle: Photosynthesis
Photosynthesis - Plants use carbon dioxide (CO2) along with water and sunlight to produce glucose (sugar) and release oxygen

15. The Carbon Cycle: Respiration
Respiration - Both plants and animals break down glucose during respiration to obtain energy. They release H2O and CO2 as waste products.
***Together photosynthesis and respiration form the basis of the carbon-oxygen cycle.
C6H12O6 + 6O2
6H2O + 6CO2

16. The Carbon Cycle: Consumption
Consumption: During their lifetime, animals pass along organic compounds from one another through feeding. Wastes produced during their lifetime are broken down by decomposers such as fungi and bacteria and CO2 is added to the atmosphere.

17. The Carbon Cycle: Decomposition
Decomposition - When living things die, these decomposers break down their organic compounds. Here again CO2 is returned to the atmosphere.

18. The Carbon Cycle: Combustion
Combustion: Any burning of fossil fuels (Oil, coal, natural gas, wood etc…). Combustion releases the energy stored in these organic compounds and also large amounts of CO2

19. The Carbon Cycle
My badCH4
CLOLO2

20. The Nitrogen cycle: Key Concepts
Plants and animals (all living things) need nitrogen to make proteins.
Plants cannot absorb nitrogen (N2) from the air.
Bacteria in the soil convert unusable (N2) from the air into nitrates (NO3) that plants can use to make their proteins.
Animals eat plants to get their proteins.

21. The Nitrogen Cycle: Cont
The nitrogen cycle mostly takes place underground.
Some bacteria convert gaseous nitrogen into ammonia through a process called nitrogen fixation.
Some nitrogen-fixing bacteria live in nodules on the roots of plants; others live freely in the soil.

22. The Nitrogen Cycle: Key Vocabulary
NITROGEN FIXING BACTERIA: convert nitrogen in the air into ammonia = nitrogen fixation.
DECAY BACTERIA: release nitrogen from dead organisms and waste as ammonia = decomposition.
NITRIFYING BACTERIA: convert ammonia into nitrates = nitrification.
DENITRIFYING BACTERIA: release nitrogen (N2) back into the air = denitrification. Occurs in oxygen poor soils.

23. The Nitrogen Cycle

25. The Phosphorus Cycle Phosphate is released by the weathering of rocks.
Phosphorus leaches into groundwater from the soil and is locked in sediments.
Both mining and agriculture add phosphorus into the environment.

26. That’s All Folks!
More to come…