Biosphere: (Phosphorous Cycle) Flashcards
Reservoirs:
-rocks.
-soil.
-oceans.
-ONLY NUTRIENT NOT AVAILABLE IN THE ATMOSPHERE!
Use of element:
-in cell membranes (phospholipids).
-ATP (energy).
-DNA.
-bones.
Phosphorus cycle:
•phosphorus is an essential nutrient but it is found in limited quantities within the environment.
•does not cycle through the atmosphere; instead, is found in rock, soil and water.
•often added to crops as fertilizer.
•weathering gradually releases phosphorus trapped in rocks.
Processes involved:
-short-term.
-long-term.
-geological uplift.
-weathering.
-runoff.
- Short-term:
•plants and algae can only use phosphorus in the form of phosphates (PO4 3-).
•phosphate is soluble in H2O so animals drink it or plants absorb it during photosynthesis.
•heterotrophs eat plants/animals.
•phosphate is returned to soil when they die and are decomposed.
- Long-term:
•bones and shells from dead animals settle on ocean floor.
•they are then covered in sediment.
•over time, rocks form containing phosphates.
- Weathering:
•weathering gradually releases phosphorus trapped in rocks and makes it available to organisms.
- Geological uplift:
•over long periods of time, phosphorus-containing sedimentary rock maybe be moved from the ocean to the land.
•this process is very slow: 20,000 to 100,000 years.
- Runoff:%
•algal growth in aquatic ecosystems is limited by available nutrients.
•because it is scarce in the environment, excess phosphorus in aquatic ecosystems (from fertilizer runoff) can result in algal overgrowth, known as an algal bloom.
•more organic matter in the water = more decomposition = less O2 = fish die.
Human impacts:
•global warming = more severe storms = more erosion and weathering = more run-off into oceans.
•fertilizers and detergents that contain phosphorus lead to eutrophication.
