Chapter 61 



The Role of Bacteria in the Mineralization 

 of Phosphorus in Lakes 



F. R. Hayes 



w 



hen phosphorus is added to marine or fresh-water ponds, 

 nearly all of it disappears in a few days ( 6, 7, 9 ) . By analogy with 

 agriculture, the decline has sometimes been attributed to new 

 plant growth. The theory of growth stimulation, however, re- 

 quired reconsideration when it was discovered that tracer phos- 

 phorus atoms, measured as radioactivity, diminished in the water 

 in the same way as large masses of fertilizer (4, 8) . It now appears 

 that there is a single pool of phosphorus belonging to water and 

 solids, which is distributed between them in a dynamic equili- 

 brium or steady state. Disappearance of phosphorus from water 

 is a consequence of an experimental arrangement in which phos- 

 phorus is added to the water phase. Were the opposite technique 

 followed, of taking up phosphorus from the water on, say ion- 

 exchange resins, a continuous replacement from the solids would 

 be expected. 



The foregoing interpretation does not deny the general ob- 

 servation that addition of fertilizers stimulates growth. Obviously 

 after equilibration there will be more nutrient in the system than 

 before. The point is that the decline of phosphorus in the water 

 phase is not a measure of increased productivity, since its rate will 

 tend to be independent of the quantity added. 



The purpose of this paper is to discuss the effect of micro- 

 organisms on the phosphorus exchange reaction between water 

 and the sediments, plants and zooplankton. 



For the experiments, a sample of natural water was brought 

 to the laboratory with precautions to prevent undue multiplica- 

 tion of microorganisms. To an 8 oz. wide-mouthed jar of the wa- 

 ter, antibiotics (terramycin and later the more powerful tetra- 



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