Peak phosphorus - what are the sinks?
The phosphorous sinks are the ocean and ocean sediments.  

The ocean holds $3 \times 10^{15}$ moles of phosphorous.  

The annual amount of phosphorous input into the ocean, as well as the amount of burial of phosphorous as sediment is on the order of $10^{10}$ moles. 

The sediment is of three categories:


Phosphorous associated with calcium carbonate
Organic phosphorous (associated with organic carbon)
Apatite


See Phosphorous Accumulation in Marine Sediments and the Oceanic Phosphorous Cycle for a detailed analysis.