Biogeochemical cycles

Energy flow

Sun → autotrophs→ heterotroph→ heat

Biotic

Relating to or resulting from living things

Abiotic

Not derived from living organisms

Reservoir for carbon, oxygen, nitrogen and water

The atmosphere

Reservoir for phosphorus, sulfur and potassium

Soil

How are oxygen and carbon dioxide cycles between abiotic and biotic components

Photosynthesis and cell resp

How much carbon in organic matter comes from CO2

Over half

How does phytoplankton take in CO2

Dissolved (HCO3)

Describe the carbon and oxygen cycle

Examples of carbon long term cycle

Formation of oil and gas: burning recycles this carbon

How is the carbon in shells returned to the atmosphere

Volcanic activity and geologic uplift and erosion

Rapid cycling of carbon

CO2 in the atmosphere goes into photosynthesis for biotic environments and through respiration, it is returned. It is also dissolved in water in the surface ocean and is returned through evaporation

Slow cycling of carbon

Dead organisms go to the deep ocean and either: go back to the surface ocean or continue to the earths crust. Here, due to weathering, they will go back to the surface ocean or be formed into petroleum deposits. Photosynthesis in biotic environments can also form fossil fuels. The fossil fuels are combusted and return to the atmosphere

Where is most of carbon located

Aquatic systems (50 times as much as the atmosphere) the ocean is a carbon sink

Human impact on CO2

* burning of fossil fuels
* Deforestation: decreases the amount of carbon that is removed from the atmosphere
* Ozone depletion: increases UV light which is harmful to phytoplankton, less carbon removed from oceans

Climate Change and CO2

* higher CO2 levels increase global average temperature
* Higher levels of greenhouse gases traps low energy long wave thermal radiation: warming the earth

Do organisms need nitrogen?

Yes. It is an element in genetic material

The nitrogen cycle

How is can plants use nitrogen

It has to be reduced ( or fixed ) into ammonium by lightning or prokaryotes

Prokaryotes

Nitrogen fixing bacteria like rhizobium, soil bacteria and Cyanobacteria in oceans are important because not enough nitrogen can be fixed by lightning alone

Nitrification

* occurs when ammonium is converted to nitrites and then nitrates
* The nitrates are soluble and can be absorbed by plants to make proteins
* NH4→NO2→ NO3

Denitrification

* a build up of nitrogen is detrimental to plant growth
* Denitrifying bacteria change nitrates back into nitrogen gas which diffuses out of the ground into the atmosphere to maintain balance

Human impact on the nitrogen cycle

* nitrogen overload: the addition of nitrogen to plants increases growth, extra nitrogen collects in streams and lakes, it affects tree roots and stints tree growth
* Combustion: burning fossil fuels results in nitrogen containing compounds to be released. They can combine with oxygen to cause acid deposition. This damages trees by dissolving the waxy layer on leaves, making trees more prone to acid rain
* Agriculture run off: with phosphorus, nitrates result in the eutrophication of nutrients in aquatic ecosystems

Why is phosphorous important to organisms

Needed to make atp and dna. Found in bones, teeth and shells

The main reservoirs for phosphorus

Soil and rocks

How can plants absorb phosphorus

Rock weathering: adds phosphorous to soil in the form of phosphate

How is phosphorus returned to soil

Animal excretion and decomposers

How is ocean bottom phosphorus returned to the surface

Geological uplift

Phosphorus cycle

Human impact on the phosphorus cycle m

Eutrophication: part of agal growth in lakes. Phosphates provide nutrients for agal growth but fertilizer run off, organic matter wastes, animal waste and mining contribute to an acceleration of eutrophication. Excessive amounts of phosphorus results in an increase of photosynthetic organisms. When large amounts of algae die, decomposers use up all the oxygen available to other organisms