Chapter 22- biogeochemical cycles

The carbon cycle

Major source of C is the atmosphere in form of CO2

Where is a large amoung of carbon locked up in

Organic matter, living and dead

What are the main reservoirs of carbon

Oceans, atmosphere, fossil fuel deposits in sediments

What are the main biotic flows of carbon

Photosynthesis and respiration (decomposers too!)

Why is ‘deforestation’ noted as an outflow of C?

Reduction of photosynthesis and plant growth and increase in decomposition following.

What is a major nutrient for plant and animal growth

Nitrogen

How does most nitrogen exist

Pools of N2 gas in atmosphere

Where can you find ammonia and nitrate

By-products of decomposition and in living and dead organic matter

What is the purpose of lighting in nitrogen fixation

Conversion of N2 to inorganic nitrate (minor portion of total N)

What two bacteria are involved in Nitrification

Nitrosomes and nitrobacter

What products come nitrosomonas and ammonia

Nitrite

Nitrobacter converts nitrite

Nitrate

What forms of nitrogen can plants take up

Ammonium or nitrate

Denitrification

Conversion of nitrate to N2 gas by pseudomonas bacteria

What is the only natural source of P

Phosphate sedimentary rocks

Where is most phosphorus locked up in

Phosphate sediments and soils. Dissolved in oceans.

What is a major constituent of air pollution and acid rain but is not a major requirement usually in nature

Sulfur

Chemosynthesis

Bacteria use sulfur as an energy source instead of solar radiation

What element is bound in sediments: Hydrogen ____ and Iron _____

Sulfide

Where does most sulfur come from

Human activities

What cause natural fluxes of sulfur

Volcanic activity and biogenic gases

What is the theory behind why there is so much gaseous O2

From the evolution