128 R. T. Prentki et al. 



4 hr. 



a) Concentrations of phosphate (DRP) and 

 surplus phosphate. The dashed lines ending in 

 arrows denote the direction of the change in 

 concentration and the final phosphate concen- 

 trations in 3-hr bottle incubations. The lines at 

 each point are the range of duplicate analyses. 



4 hr. 



b) Concentrations of colloidal P in the same 

 samples. The lines at each point are the stand- 

 ard error of duplicate difference calculations. 



FIGURE 4-17. Concentrations of DRP, surplus 

 phosphate and colloidal P in Pond B, 30 June 

 through 2 July 1972. 



