26. Nutrient Cycles I Flashcards
flows/cycles
energy flows (one-way trip), nutrients cycle (round and around)
reservoirs
stores of water or nutrients in a cycle
macronutrients
essential elements required in
large concentrations in an organism: carbon, hydrogen, oxygen, nitrogen, phosphorus
micronutrients
essential elements required only in small concentrations in an organism: iron, magnesium, iodine, selenium, zinc
phosphorous cycle
- Plants take up phosphate ions from soil or water and incorporate them directly into tissue
- Animals gain phosphate by eating these tissues, or from the tissues of other organisms
- Animals eliminate excess phosphorus through urine
nitrogen cycle
- The biggest reservoir of N is the atmosphere (as N2 gas).
- Nitrogen can be fixed, through nitrogen fixation, by certain prokaryotes. It also can be fixed by lightning!
- During nitrogen fixation, N2 gas is reduced to ammonia, NH3: N2 + 8 H+ → 2 NH3 + H2
- After fixation, nitrogen it is available to primary producers and can be immobilized (assimilated into their tissue).
- Consumers can gain nitrogen by eating these primary producers or other organisms.
- Once an organism dies, nitrogen is released from its tissues by fungi and bacteria during decomposition.
- Nitrogen released through mineralization, also called
ammonification. During this process the organic nitrogen is converted into ammonium NH4+ - This ammonium can then be converted into nitrate through nitrification (a two-step process)
- Nitrogen re-enters the atmosphere reservoir through denitrification, when denitrifying bacteria convert nitrate into N2 gas
carbon cycle
- Some of the big carbon reservoirs are the atmosphere, terrestrial soils, all organisms, and the oceans.
- Carbon moves between organisms and the atmosphere through respiration and photosynthesis.
- Respiration moves carbon to the atmosphere
- Photosynthesis removes carbon from the atmosphere
- humans are messing up the balances in the carbon
cycles, thus are creating global climate change by burning fossil fuels, vegetation, and peat
decomposition
the breakdown of organic matter accompanied by the release of CO2
factors that influence decomposition
- Temperature
- Moisture
- Chemical composition of decaying matter
- Chemical composition of the environment
factors that influence decomposition: temperature
annual leaf mass loss in tropical forests is about three times that occurring in temperate forests
factors that influence decomposition: moisture
increased precipitation = increased decomposition
chemical composition of decaying matter
Higher the ratio of lignin to N, the longer it took to decompose
chemical composition of the environment
the more N in the soil, the higher the decomposition rate
nutrients
elements that are required for the development, maintenance, and reproduction of organisms
phosphorous
- Essential to energetics, genetics and structure of living systems.
- main component of ATP, RNA, DNA, and phospholipid molecules
- Not very abundant in the biosphere
- Does not have an atmosphere reservoir
- Can be a limiting factor for aquatic primary production, not usually for terrestrial primary production
nitrogen
- Important to structure and functioning of organisms.
- May limit rates of primary production in terrestrial and marine systems.
- One of the biggest reservoirs is the atmosphere (Earth’s atmosphere = 78% N)
- Microbes play a BIG role in the nitrogen cycle
forms of nitrogen
Ammonia: NH3 Ammonium: NH4+ Nitrite: NO2- Nitrate: NO3- Nitrogen gas: N2 Nitric oxide: NO
5 transformations of N
- nitrogen fixation
- immobilization
- mineralization (ammonification)
- nitrification
- denitrification
nitrogen fixation
the process of converting atmospheric nitrogen into forms primary producers can use
immobilization
the conversion of mineral forms of nitrogen (ex. ammonia and nitrate) into organic forms (ex. proteins)
mineralization (ammonification)
the conversion of organic forms of nitrogen (ex. proteins) into mineral forms (ex. ammonia and nitrate)
nitrification
the conversion of ammonium(NH4+) to nitrite (NO2), and then nitrite (NO2) to nitrate (NO3-)
denitrification
the process of converting nitrate
NO3-) into nitrogen gas (N2
carbon
It makes organic molecules organic. We humans are messing up the balances in the carbon cycles, thus are creating global climate change
carbon in aquatic ecosystems
- In aquatic ecosystems CO2 has to be dissolved into the water before it is available to primary producers.
- When dissolved in water, CO2 turn into two compounds (in equilibrium):
- Bicarbonate HCO3-
- Carbonate CO32- - CO32- can combine with dissolved calcium and precipitate out as calcium carbonate CaCO3
factors that influence decomposition in aquatic ecosystems
– Temperature
– Nutrient content of the decaying matter
– Nutrient content of the water
