Energy & Matter Exchange in the Biosphere Flashcards
Albedo
- the amount of energy reflected or absorbed by clouds, water, and land.
light = high albedo | dark = low albedo
open vs closed system
- Energy = OPEN
- Matter exchange = CLOSED
PRODUCERS (Autotrophs)
- “self-feeders”
- use light energy to make sugars
- Photosynthetic producers: use the Sun’s energy make food
*Chemosynthetic producers: make own food from chemical energy stored in molecules
CONSUMERS (heterotrophs):
- “other feeders”
- obtain energy by consuming other heterotrophs or autotrophs
Consumer levels
- PRIMARY CONSUMERS are herbivores which eat producers.
- SECONDARY CONSUMERS are carnivores that eat herbivores.
- TERTIARY CONSUMERS are carnivores that eat carnivores
Trophic levels
feeding levels in an ecosystem through which energy and matter are transferred
➢ Largest amount found within the 1st trophic level
* Usually no more than 5 levels
1) Pyramids of Numbers
➢ # of producers often greatly outnumbers the # of consumers
➢ Each bar of the pyramid: # of organisms in each trophic level
2) Pyramids of Biomass
➢ Represent the dry mass of living organisms per unit area (in g/m2 )
➢ energy is transferred from one trophic level to another, takes into account the actual size of organisms in an ecosystem rather than just the number.
3) Pyramids of Energy
➢ Shows the total amount of energy that is transferred through each trophic level (in J or kJ), are always upright
Sources that increase carbon
- Hydrocarbon combustion (CO2 to atmosphere)
- Deforestation (removing carbon sink – trees – slash and burn - )
- Human caused forest fires
- Agriculture
- Acidification of oceans (CO2 in H2O à carbonic acid – impact on marine ecosystems)
Where is the Carbon?
Abiotic environment:
* CO2 in the atmosphere,
* Majority is dissolved in the world’s oceans
Biotic environment:
* Primary source is the atmosphere (CO2 )
* Captured through photosynthesis – aka carbon fixation
* Some returned to atmosphere via cellular respiration
* Reverse reaction of photosynthesis.
* Chemical energy from the breakdown of glucose is released and is used by the cell to make ATP (energy for organism)
Processes involved in the carbon cycle
- photosynthesis/chemosynthesis aka carbon fixation
- cellular respiration
- death/decay of organisms
- fossilization
- burning fossil fuels
- formation of carbonate compounds
- sedimentation
- volcanic heating of carbonate rocks (limestone)
Phosphorus cycles in two ways
- Long term – involving rocks and the earth’s crust
- Short cycle – involving living organisms
Processes Involved in the Phosphorus
Cycle
- Geological uplift
- Erosion/weathering (wind/rain)
- Decomposition
- Ingestion
- Absorption
- Leaching
- Sedimentation
- Run-off
Human Impacts
Detergents (used to contain phosphates)
- Agriculture (fertilizers)
- Golf courses
- Excess nutrients in rivers and lakes - eutrophication
nitrogen fixation
Bacteria convert nitrogen gas into ammonium (NH 3), ammonium is then converted
into nitrites (NO2) and nitrates (NO3), which can then be used by plants.
➢ Animals can only obtain nitrogen by eating plants.
denitrification
➢ Excess nitrates in the soil are converted back into atmospheric nitrogen by a
a different set of bacteria.
Nitrification
lightning converts N2 > NO3 -
Nitrogen-fixing bacteria
-convert nitrogen into ammonium for the plants, and the plants provide the bacteria with sugars produced through photosynthesis
Lightning as a cause in the nitrogen cycle
causes a reaction to occur between the nitrogen (N 2) gas in the air and the oxygen in the air.
* Result is formation of NO3 – ions which combine with water and enter the soil.
* Plants then absorb this NO3 – by their roots.
Nitrogen Fixing Bacteria as a cause in the nitrogen cycle
– bacteria fix nitrogen gas from the air, producing ammonia [NH 3(g)] (becomes ammonium ions dissolved in soil water) and nitrifying bacteria convert NH 4+ into NO 3-.
* These bacteria can be found in the soil and more often root nodules (on legumes)
* Provides the plant with more than enough nitrogen and the excess is released into the soil
Denitrifying bacteria
- anaerobic bacteria (O 2 intolerant) that live in soil
- reduce nitrates (NO 3 - ) and nitrites (NO 2 - ) to nitrogen gas (N 2 ) and nitrous oxide – which returns to atmosphere
*Note: denitrification increases in rate, if the soil is acidic or waterlogged.
Human Impacts on the nitrogen cycle
- Agriculture (fertilizers) à run off
- Excess nutrients in rivers and lakes – eutrophication
- Burning of fossil fuels à The chief culprit is fossil fuel combustion, which releases nitric oxides into the air that combine with other elements to form smog and acid rain
SULFUR CYCLE
1) Through volcanic activity, geologic uplift, or the mining & burning of fossil fuels, sulfur is then released into the air in the form of sulfur dioxide (SO2 )
2) Sulfates do not stay in the air for very long; they are returned to the earth through acid precipitation (caused primarily by the burning of fossil fuels)
3) Bacteria in the soil then allow the sulfates to be used by plants. These sulfur compounds return to the soil once the plants die and decompose
4) Some of the sulfur returned to the ground is also re-deposited in rocks, and the cycle continues
