10 



J. E. Hobbie 



Flux of Phosphorus 



Phosphorus enters the ponds in rainfall (8 ng P liter"') and in 

 overland flow. The quantities entering a pond are small and are equaled by 

 the losses. We did measure an annual loss of 0.7 mg P m^^ but this 

 amount is minuscule relative to the 25,000 mg P m "^ found in the top 10 

 cm of sediments. In spite of the large amounts of phosphorus present, the 

 concentrations of inorganic phosphorus in the waters of the pond and in 

 the interstitial water of the sediments is always extremely low, between 



0.00005 



r 



0.4: 



Phytoplankton 

 0.027 



0.015 



0.033 



0.0075 



Sestonic 



Bacteria 



0.14 



0.13 



0.074 



Zooplankcon 

 1.4 



t 



0.084 



0.07 



O.U 



Sestonic 

 Detritus 



0.17 



0.42 



r 



1.0 



0.42| 

 I 0.42 



Woter 



0.11 



0.72 



1.1 



1.2 



0.73 



1.2 



Benthic 

 Algae 



17 



0.007 3 



oTZT 



_1_ 



3.G 



Benthic 



liacteria 



56 



-1 



0.002fi 



L_ 



7.2 



Benthic 



Animals 



22 



0.47 



-a (N 

 <u • 

 > o 



i 



T 



11 



_i_ 



1.2 



0.39 



Sediment 



10 cm 



5 cm 



Sediment and Detritus 

 10000 



^ 



-1 



FIGURE 1-7. Phosphorus flow diagram in a tundra pond for 12 July 

 1971. Units are mg P m'^ and mg P m'^ day'\ Fluxes were measured 

 whenever possible (Prentki 1976) or were based on the carbon flux data 

 (Figure 1-5). 



