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BIOL 208 > Nutrient Cycling > Flashcards

Nutrient Cycling Flashcards

1
Q

What is Ecosystem Ecology?

A

focuses on understanding how organisms and chemical and physical processes interact

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2
Q

What is an ecosystem?

A

a region that contains interaction biotic and abiotic factors

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3
Q

Energy flow vs. Nutrient Cycling

A
  • energy flows through ecosystems = one way trip
  • nutrients cycle = nutrients are continuously recycled
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4
Q

Biogeochemistry

A

the study of the physical, chemical and biological factors that influence the movements and transformations of elements

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5
Q

Two ways that nutrients enter the ecosystem?

A
  1. chemical breakdown of minerals in rocks
  2. fixation of atmospheric gases
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6
Q

Macronutrients and examples

A

essential elements required in large concentrations
- examples include: carbon, hydrogen, oxygen, nitrogen, phosphorus

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7
Q

Micronutrients and examples

A

essential elements required, but only in small concentrations
- examples include: iron, magnesium, iodine, selenium, zinc

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8
Q

What are the functions of Carbon, Nitrogen, and Phosphorus?

A

C - main components of structural compounds
N- enzymes
P - ATP, DNA, cell membranes

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9
Q

Physical weathering

A
  • 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
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10
Q

Chemical Weathering

A
  • chemical reactions that release soluble forms of the mineral elements
  • e.g., acid rain causing pitting in limestone
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11
Q

Biological Weathering

A
  • plant roots, lichens
  • often classified as mechanical or chemical
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12
Q

What is Soil?

A
  • a mix of mineral particles, organic matter (mostly decomposing plant mater), water (containing DOM, minerals, gasses) and organisms
    -NOT dirt
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13
Q

What are soil horizons and how do they form?

A
  • form from weathering
  • accumulation of organic matter and leaching
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14
Q

Phosphorus (P) Cycle

A
  1. weathering: P is usually (naturally) released to ecosystems via weathering of rocks
  2. Absorption: plants uptake P from soil/water and incorporate them directly into tissue (animals gain phosphate via plant tissue)
  3. return to environment - decomposition
  4. some P gets buried in settlements, which over time, becomes rock
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15
Q

Nitrogen Cycle

A
  1. nitrogen-fixing bacteria capture N2, converting it to ammonia or ammonium in the soil
  2. this is than taken up by plants and used to make organic molecules
  3. the nitrogen-containing molecules are passed to animals when the plants are eaten
  4. they may be incorporated into the animal’s body or broken down and excreted as waste, such as the urea found in urine
  5. when the animal dies, the N is returned to the soil via decomposition
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16
Q

Nitrogen Fixation

A
  • is energetically costly
  • specialized bacteria enable N input into ecosystems
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17
Q

What is mineralization/ammonification?

A
  • 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
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18
Q

Process of Nitrification

A

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

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19
Q

Is Nitrite a Fertilizer? why or why not?

A

yes it is, because it can be assimilated to make biomolecules

20
Q

What is Denitrification? How is it done?

A

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

21
Q

Explain the Carbon Cycle

A
  • 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
22
Q

Carbon Cycle in Terrestrial Ecosystems

A

-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

23
Q

Carbon Cycle in Aquatic Ecosystems

A
  • 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
24
Q

Where in the Earth’s interior is Carbon also stored?

A

in the lithosphere, includes: coal, oil, natural gas

25
Q

What is the process of Decomposition?

A
  • process by which organic matter is broken down into simpler organic or inorganic matter
  • accompanied by a release of CO2 as well as nutrients are released for uptake by primary producers
26
Q

How are Decomposition rates influenced?

A
  • temperature - warmer temps mean faster rates of reactions
  • moisture
  • chemical composition of decaying matter
  • chemical composition of the environment
27
Q

Actual Evapotranspiration

A

a measure of the total amount of water that evaporates and transpires off of a landscape

28
Q

Decomposition rates in Aquatic Environments

A
  • increase with increasing temp
  • decrease with increasing structural tissue content
  • increase with nutrient availability
  • moisture becomes unimportant as a factor regulation decomposition in aquatic ecosystems
29
Q

How can nutrient cycling by altered by organisms?

A
  • plants and animals modify the distribution/cycling of nutrients in ecosystems
  • lower rate of consumption in terrestrial ecosystems has important implication for carbon flow: there is relatively more carbon immobilized as detritus and detritivores
30
Q

Carbon flow in Aquatic ecosystems vs. Terrestrial ecosystems

A

aquatic: higher herbivory rates, less autotroph biomass, less detritus, less detritivore biomass, overall QUICKER cycling of nutrients

terrestrial: lower herbivory rates, more autotroph biomass, more detritus, more detritivore biomass, overall SLOWER cycling of nutrients

31
Q

What is nutrient spiralling?

A

a result of nutrient cycling not occurring in a single stationary location

32
Q

Spiralling length? What does it mean when a spiralling length is short?

A

the length of stream required for an atom of a nutrient to complete a cycle from release into the water column to re-entry into the benthic environment
- where spiralling lengths are short, a particular nutrient atom may be used many times before it is washed out of a stream system

33
Q

What two properties are nutrient spirals characterized by?

A
  1. spiralling length
  2. nutrient retentiveness: the tendency of a stream to retain nutrients. Inversely related to spiralling length
34
Q

What does long spiralling length mean?

A
  • low nutrient retentiveness
  • nutrient availability low because nutrients transported downstream more quickly
  • nutrient atom used few times before being washed downstream
35
Q

What does a shorted spiralling length mean?

A
  • high nutrient retentiveness
  • nutrient availability high because nutrients transported downstream more slowly
  • nutrient atom used many times before being washed downstream
36
Q

What does a high abundance of macroinvertebrates lead to?

A
  1. speed up the nutrient cycling in streams (faster nutrient cycling = greater primary production
  2. higher nutrient retention and decrease of downstream nutrient transport
37
Q

Effect of Large Grazers on nutrient cycling

A
  • large grazers may increase primary productivity of ecosystem through increased rates of nutrient cycling
  • heavy grazing shifts composition of plants (eat more palatable species, leaving behind seedlings of less palatable species)
38
Q

How are Humans screwing up the distribution and cycling of nutrients in ecosystems?

A
  • usage of artificial fertilizers and Haber process
  • acid rain as a results of combustion processes
  • nitrates in the drinking water
  • N-deposition and change in terrestrial vegetation
  • human influence of carbon cycle
  • deforestation on carbon cycle
39
Q

What is the Haber Process?

A
  • artificial nitrogen fixation
  • combines N2 and H2 gas using a metal catalyst under high heat and pressure to form NH3
  • discovered in 1910
  • NH3 injected into soil, quickly turned into nitrite/nitrate
40
Q

What is Acid Rain?

A

nitrogen oxidizes, produced by combustion (industry, households, vehicles), when combines with water vapour form acid

41
Q

Name problems that are caused by Acid Rain

A
  • forest dieback
  • decrease of pH in aquatic and terrestrial ecosystems
  • corrosion of human infrastructure
  • negative impacts on human health
  • acid rain can impact areas distant from the origin
42
Q

Acid Rain research and regulation

A
  • relatively well researched since the industrial revolution
  • governments have adopted strategies to reduce acid rain, mostly through catalytic converters
43
Q

What is Methemoglobinemia?

A
  • aka “baby blue syndrome”
  • nitrates in drinking water (usually from agricultural runoff) can cause hemoglobin in blood to oxidize, reducing its capacity to carry O2
  • infants suffer from low O2 levels when consuming water with high nitrate levels because of low levels of methemoglobin and their inability to counteract hemoglobin oxidation
44
Q

Why is there such increased nitrate concentrations?

A

mainly due to soil erosion

45
Q
A

BIOL 208 (30 decks)

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