Phosphorus Release from Bog Lake Muds1

The paper reports the results of some laboratory investigations concerning the mud-water phosphorus relationship of some Northern Wisconsin and Upper Michigan bog lake muds as influenced by lime, acid, and mechanical agitation. Calcium carbonate added to the water phase of mud-water systems reduced the amount of soluble phosphorus from 8.0 to 0.8 parts per billion. The lime formed a thin crust at the mud-water interface, while the original pH of the bottom material prevailed at a depth of one-fourth inch below the mud surface. Agitation of the mud cores by stirring resulted in complete lime penetration throughout a three-inch core. Experimental apparatus in which it is possible to obtain a 12°C tempcraturc differential for stratifying water is described. Radioactive ordinary superphosphate fertilizer was placed at various depths below the mud surface, and the percentage as well as the amount of phosphorus released to the water was indicated to bc very small with virtually no phosphorus released from depths greater than one-fourth inch below the mud surface. Agitation by stirring of the muds resulted in approximately twice the concentrations of soluble phosphorus in the water phase of the agitated systems as compared to the undisturbed systems. The most effective means of releasing fcrtilizcr phosphorus placed one-fourth inch below the mud surface was found to be the acidification of previously limed mud-water systems. The mechanism of phosphorus suppression by the addition of calcium compounds to mud water systems is suggested to bc adsorption of phosphate ions onto th.e surface of the cal-cium particles in a similar manner as that described by Boischot et al. Large quantities of phosphorus are con-sistently found deposited in lake muds, but often the quantities of soluble phosphorus found in the waters are very small. If a mechanism could be discovered to increase the release of the phosphorus from the bot-tom muds so that it could contribute to the production of algae, and hcncc fish, it would be a valuable contribution. This research reports the results of some labora-tory investigations concerning the mud-water phosphorus relationship as influenced by lime, acid, and mechanical agitation