Phosphorus

Question 1

Sources of phosphorus

Answer 1

Geological – phosphate minerals, e.g. apatite
Ca5 (PO4)3+

Groundwater
Pollution and run-off – fertilizer, detergents
Airshed – fertilizer dust, phosphoric acid
Sediments and airshed - Phosphine gas (PH3)
Sediments - PO4 3- bound to clay released back into
lake under anoxic conditions

Question 2

Sedimentation

Answer 2

Builds up in the sediments

no longer biologically available

• Phosphorous “legacy” in sediments can reintroduce

Question 3

Adaptations to Low Phosphate

Answer 3

Store it

Be good at taking it in at low concentrations

be good at braking it up from complex molecules

Question 4

Redfield Ratio

Answer 4

Carbon: Nitrogen: Phosphorus - 106:16:1 (organic matter)

–this is found everywhere

Question 5

Nutrient Limitation

Answer 5

Nitrogen: Phosphorus
• >16:1 phosphorous limitation
• <16:1 nitrogen limitation

Can influence community composition

Question 6

Why is Phosphorus Limitation a problem

Answer 6

Release of new phosphorus slow by rock
weathering

Land and littoral plants intercept available
phosphorus

Low delivery from atmospheric sources