Nutrient Cycling Flashcards
(45 cards)
What is Ecosystem Ecology?
focuses on understanding how organisms and chemical and physical processes interact
What is an ecosystem?
a region that contains interaction biotic and abiotic factors
Energy flow vs. Nutrient Cycling
- energy flows through ecosystems = one way trip
- nutrients cycle = nutrients are continuously recycled
Biogeochemistry
the study of the physical, chemical and biological factors that influence the movements and transformations of elements
Two ways that nutrients enter the ecosystem?
- chemical breakdown of minerals in rocks
- fixation of atmospheric gases
Macronutrients and examples
essential elements required in large concentrations
- examples include: carbon, hydrogen, oxygen, nitrogen, phosphorus
Micronutrients and examples
essential elements required, but only in small concentrations
- examples include: iron, magnesium, iodine, selenium, zinc
What are the functions of Carbon, Nitrogen, and Phosphorus?
C - main components of structural compounds
N- enzymes
P - ATP, DNA, cell membranes
Physical weathering
- physical breakdown of rocks (e.g., freeze/thaw; drying/re-wetting; landslides)
- break rocks into smaller and smaller particles, increasing surface area available for chemical weathering
Chemical Weathering
- chemical reactions that release soluble forms of the mineral elements
- e.g., acid rain causing pitting in limestone
Biological Weathering
- plant roots, lichens
- often classified as mechanical or chemical
What is Soil?
- a mix of mineral particles, organic matter (mostly decomposing plant mater), water (containing DOM, minerals, gasses) and organisms
-NOT dirt
What are soil horizons and how do they form?
- form from weathering
- accumulation of organic matter and leaching
Phosphorus (P) Cycle
- weathering: P is usually (naturally) released to ecosystems via weathering of rocks
- Absorption: plants uptake P from soil/water and incorporate them directly into tissue (animals gain phosphate via plant tissue)
- return to environment - decomposition
- some P gets buried in settlements, which over time, becomes rock
Nitrogen Cycle
- nitrogen-fixing bacteria capture N2, converting it to ammonia or ammonium in the soil
- this is than taken up by plants and used to make organic molecules
- the nitrogen-containing molecules are passed to animals when the plants are eaten
- they may be incorporated into the animal’s body or broken down and excreted as waste, such as the urea found in urine
- when the animal dies, the N is returned to the soil via decomposition
Nitrogen Fixation
- is energetically costly
- specialized bacteria enable N input into ecosystems
What is mineralization/ammonification?
- release of N as ammonium (NH4+) following decomposition by bacteria and fungu
- excreteion of ammonium by all organisms
- ammonium can be directly taken up (immobilized) by bacteria and primary producers
Process of Nitrification
conversion of ammonium to nitirite and then quickly nitrate
- preformed by Nitrifying bacteria- these bacteria oxidize (i.e., add O2) the ammonium
- happens best in soils well-aerated soils
Is Nitrite a Fertilizer? why or why not?
yes it is, because it can be assimilated to make biomolecules
What is Denitrification? How is it done?
conversion of nitrate to nitrous oxide (N2O), then dinitrogen (N2) gas
- done by denitrifying bacteria - best in low oxygen soils- reduces the fertility of the soil
- is the primary mechanism through which nitrogen is lost from ecosytems
Explain the Carbon Cycle
- its what makes organic molecules, organic
- carbon gasses play a critical role in controlling global climate
- carbon is removed for the atmosphere via photosynthesis (couples with uptake of essential nutrients)
- carbon is returned to the atmosphere via respiration
- active recycling is rapid; long terms pools include sedimentary rocks and carbon buried in fossil fuel reserves
Carbon Cycle in Terrestrial Ecosystems
-CO2
is removed from the atmosphere via photosynthesis (in plants/algae/ cyanobacteria)
* used to create organic molecules and biological mass.
* Animals consume the primary producers, acquire C that is stored within them.
CO2 is returned to the atmosphere via
* respiration in all living organisms.
* Decomposers can also break down dead / decaying organic matter and release CO2
- Some CO2
is returned to the atmosphere via the burning of organic matter
(forest fires).
* CO2 trapped in rock or fossil fuels can be returned to the atmosphere via
erosion, volcanic eruptions, or burning of fossil fuels
Carbon Cycle in Aquatic Ecosystems
- CO2 has to be first dissolved in water before it is available to primary producers
when dissolved CO2 turns into two compounds in equilibrium: bicarbonate, carbonate - Carbonate may combine with dissolved calcium to precipitate out as calcium carbonate
Where in the Earth’s interior is Carbon also stored?
in the lithosphere, includes: coal, oil, natural gas
