Nutrient Cycles Flashcards
Why is the phosphorus cycle a slow process?
No gas phase, so there is no atmospheric cycle
Most phosphorus is stored as PO4 3- in rocks
What happens during weathering and runoff?
Phosphate compounds from sedimentary rocks leach into surface water and soil
Significance of phosphorus to living organisms
Convert inorganic phosphate into biological molecules e.g DNA, ATP
Phosphorus is passed to consumers via feeding
What happens during uplift?
Sedimentary layers from oceans are brought up to land over many years
How does mining affect the phosphorus cycle?
Speeds up uplift
Role of mycorrhizae
Mutualistic relationship between plant and fungus increases surface area of root system
= increases uptake of water and mineral ions
2 categories of fertiliser and state the purpose of using fertiliser
Organic - decaying organic matter and animal waste
Inorganic - minerals from rocks, usually containing nitrogen, phosphorus, potassium.
To increase gross productivity for higher yield.
2 main environmental issues caused by the use of fertilisers
- Leaching - nitrates dissolve in rainwater and ‘runoff’ into water sources
- Eutrophication - water source becomes putrid as a result of algal bloom
What happens during eutrophication
- Aquatic plants grow exponentially since nitrate level is no longer a limiting factor
- Algal bloom on water surface prevents light from reaching the bottom and plants die
- Oxygen levels decrease as population of aerobic saprobionts increases to decay dead matter, so fish die
- Anaerobic organisms reproduce exponentially and produce toxic waste which makes water putrid
How can the risk of eutrophication be reduced
• sewage treatment marshes on farms
• pumping nutrient-enriched sediment out of water
• using phosphate-free detergent
What molecules contain nitrogen
Nucleic acids
RNA
DNA
ATP
Proteins
Makes haem in haemoglobin
What is nitrification
Ammonium (NH4+) is converted into nitrite ions (NO2-) is converted into nitrate ions (NO3-)
What is nitrogen fixing
Nitrogen from the atmosphere is converted into nitrogen containing compounds
There are two types
- free living bacteria in the soil
- bacteria living in root nodules of legumes
What is denitrification
Denitrifying bacteria converts nitrate ions back into nitrogen in the atmosphere
Usually occurs in waterlogged conditions
What is ammonification
Ammonia is produced from organic ammonium-containing compounds.
Saprobiotic bacteria carry this out - they break down dead matter of animals
